Water-Resources Investigations Report 02-4059

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

U.S. Geological Survey

Effectiveness of Three Best 

Management Practices for 

Highway-Runoff Quality along the 

Southeast Expressway, 

Boston, Massachusetts

By KIRK P. SMITH

Water-Resources Investigations Report 02-4059

In cooperation with the

FEDERAL HIGHWAY ADMINISTRATION, and the

MASSACHUSETTS HIGHWAY DEPARTMENT

Northborough, Massachusetts

2002
U.S. DEPARTMENT OF THE INTERIOR

GALE A. NORTON, Secretary

U.S. GEOLOGICAL SURVEY

Charles G. Groat, Director

The use of trade or product names in this report is for identification 

purposes only and does not constitute endorsement by the 

U.S. Government.

For additional information write to: Copies of this report can be purchased 

Chief, Massachusetts-Rhode Island District U.S. Geological Survey

U.S. Geological Survey Branch of Information Services

Water Resources Box 25286

10 Bearfoot Road Denver, CO 80225-0286

Northborough, MA 01532

or visit our Web site at

http://ma.water.usgs.gov

Chief Engineer

Massachusetts Highway Department

10 Park Plaza

Boston, MA 02116
Pr

PREFACE

Knowledge of the characteristics of highway runoff (concentrations 

and loads of constituents and the physical and chemical processes which 

produce this runoff) and the performance of best management practices 

are important for decision makers, planners, and highway engineers to 

assess and mitigate possible adverse impacts of highway runoff on the 

Nation’s receiving waters. In November 1998, the Federal Highway 

Administration, the Massachusetts Highway Department, and the U.S. 

Geological Survey began an investigation to determine the effectiveness 

of three best management practices in reducing suspended-solid loads and 

related constituents along the Southeast Expressway (Interstate Route 93) 

in Boston, Massachusetts.

Office of Natural Environment

Federal Highway Administration

55 Broadway, 10th Floor

Cambridge, MA 02142

Massachusetts Highway Department

10 Park Plaza

Boston, MA 02116

U. S. Geological Survey

10 Bearfoot Road

Northborough, MA 01532

Con

CONTENTS

Abstract .............................................................................................................................................................................

Introduction .......................................................................................................................................................................

Description of Study Area and Highway-Drainage Systems ..................................................................................

Acknowledgments ...................................................................................................................................................

Methods for Continuous Monitoring of Highway Drainage.............................................................................................

Design of Highway-Drainage Monitoring Stations.................................................................................................

Measurement of Discharge......................................................................................................................................

Measurements of Turbidity, Specific Conductance, and Water Temperature..........................................................

Collection and Analysis of Samples..................................................................................................................................

Automatic Sample Collection .................................................................................................................................

Suspended Sediment .....................................................................................................................................

Water Chemistry............................................................................................................................................

Bacteria..........................................................................................................................................................

Miscellaneous Debris Samples................................................................................................................................

Measurement of Volume and Mass of Bottom Material in the Oil-Grit Separators and the Catch Basin...............

Collection of Bottom-Material Samples from the Oil-Grit Separators ...................................................................

Sediment Samples from Mechanical Street Sweepers ............................................................................................

Quality Assurance/Quality Control ...................................................................................................................................

Quality-Control Samples.........................................................................................................................................

Quality-Control Data...............................................................................................................................................

Analysis of Data ................................................................................................................................................................

Suspended-Sediment Loads ....................................................................................................................................

Efficiencies of Structural BMPs ..............................................................................................................................

Annual Suspended-Sediment Loads........................................................................................................................

Predictors for Unsampled Suspended-Sediment Loads ..........................................................................................

Assessment of Best Management Practices ......................................................................................................................

Temporal Variability of Retained Bottom Material.................................................................................................

Particle-Size Distribution and Contents of Retained Bottom Material ...................................................................

Reduction of Debris and Litter................................................................................................................................

Variability in Suspended-Sediment Concentration Samples...................................................................................

Effectiveness of Oil-Grit Separators in Reducing Suspended-Sediment Concentrations .......................................

Effectiveness of Deep-Sumped Hooded Catch Basins in Reducing Suspended-Sediment Concentrations ...........

Estimated Loads of Suspended Sediment in the Study Area ..................................................................................

Mechanized Street Sweeping ..................................................................................................................................

Variability of Concentrations of Chemical Constituents in Sediment.....................................................................

Reduction of Chemical Constituent Loads Discharged in Storm Flows.................................................................

Reduction of Fecal-Indicator Bacteria ....................................................................................................................

Summary ...........................................................................................................................................................................

References Cited ...............................................................................................................................................................

Appendix 1. Summary Statistics and Analytical Results from the Evaluations of Effectiveness for Three 

Best Management Practices for Highway-Runoff Quality along the Southeast Expressway, 

Boston, Massachusetts .................................................................................................................................. CD

FIGURES

1. Map of study area where best management practices were tested, Southeast Expressway, Boston, 

Massachusetts ....................................................................................................................................................

2. Schematic section of a deep-sumped hooded catch basin and a 1,500-gallon off-line oil-grit separator..........
VI Contents

3. Map showing actual drainage area of (A) 749, (B) 739, and (C) 136 along the Southeast Expressway ...........

4. Graph showing specific conductance, turbidity, and stage measured at highway runoff monitoring 

station 739, September 10–11, 1999, Southeast Expressway............................................................................

5. Schematic diagram of a static mixer used in conjunction with the automatic samplers ...................................

6. Graph showing example of automated flow-proportional collection of stormwater samples at station 739.....

7. Photograph of debris-collection structure at the outlet of an oil-grit separator during a rainstorm on 

May 25, 2000, station 739, Southeast Expressway ...........................................................................................

8. Graph showing general trend for flow-weighted suspended-sediment concentrations relative to the 

sample location in the water column of a 12-inch pipe at the inlet of the oil-grit separator at station 136.......

9. Box plot showing distribution of runoff flows at time of sample collection for the inlet and outlet of each 

structural best management practice..................................................................................................................

10, 11. Bar charts showing: 

10. Distribution of inorganic elements by particle size in sediment samples collected from oil-grit 

separators located along the Southeast Expressway..................................................................................

11. Distribution of organic constituents by particle size in sediment samples collected from oil-grit 

separators located along the Southeast Expressway..................................................................................

12. Box plot showing particle-size distribution for samples of suspended sediment collected from the inlet 

and outlet of a deep-sumped hooded catch basin and two oil-grit separators located along the 

Southeast Expressway .......................................................................................................................................

13. Graph showing relation of suspended-sediment concentrations to laboratory measurements of turbidity 

in samples collected from the outlet of a deep-sumped hooded catch basin and the inlet of two oil-grit 

separators located along the Southeast Expressway..........................................................................................

14–16. Bar charts showing: 

14. Total precipitation measured at station 136 for each runoff event and suspended-sediment loads 

for the inlet and the outlet of a deep-sumped hooded catch basin and the inlet and outlet of two 

oil-grit separators located along the Southeast Expressway .....................................................................

15. Temporal variability of the volume of bottom material in three oil-grit separators located along 

the Southeast Expressway .........................................................................................................................

16. Particle-size distribution of a sample of bottom sediment collected from a deep-sumped hooded 

catch basin and the weighted-average particle-size distribution of samples of bottom sediment 

collected from three oil-grit separators located along the Southeast Expressway ....................................

17. Pie chart showing relative quantity and type of debris retained from April 2000 through June 2000 in a 

collection structure mounted on an outlet of an oil-grit separator located along the Southeast Expressway....

18. Graph showing suspended-sediment concentration and associated particle-size distribution in water 

moving through a deep-sumped hooded catch basin and a 1,500-gallon oil-grit separator located along 

the Southeast Expressway..................................................................................................................................

19, 20. Bar charts showing:

19. The relation of antecedent dry period to mean efficiency of oil-grit separators for precipitation 

events less than 0.2 inches.........................................................................................................................

20. Average size distribution of pavement sweepings collected from a mechanical sweeper in contrast 

to the size distribution of a bottom-sediment sample collected from a deep-sumped hooded catch 

basin and the weighted-average particle-size distribution of samples collected from three 1,500-gallon 

oil-grit separators along the Southeast Expressway..................................................................................

21. Box plot showing comparison of local soil chemistry to samples collected from oil-grit separators 

located along the Southeast Expressway ...........................................................................................................

22. Graph showing relative percent differences between inlet and outlet event mean concentrations of

selected highway runoff constituents for a deep-sumped hooded catch basin and two 1,500-gallon 

oil-grit separators located along the Southeast Expressway..............................................................................

23. Box plot showing specific conductance of suspended-sediment concentration samples collected from a 

deep-sumped hooded catch basin and two oil-grit separators located along the Southeast Expressway ..........
Cont

TABLES

1. Location and construction properties of selected structural best management practices, Southeast 

Expressway, Boston, Massachusetts ...................................................................................................................

2. Quantity and type of samples collected, and location of water level, water-velocity, water-quality, 

meteorology, and physical measurements made at each structural best management practice ..........................

3. Summary of quality-control samples collected in the structural best management practices along the

Southeast Expressway, in the U.S. Geological Survey, Massachusetts District laboratory, and by the

U.S. Geological Survey, Office of Water Quality, Branch of Quality Systems ..................................................

4. Composition of bottom material collected from a deep-sumped hooded catch basin and each chamber of 

three oil-grit separators located along the Southeast Expressway ......................................................................

CONVERSION FACTORS, WATER-QUALITY UNITS, AND ABBREVIATIONS

CONVERSION FACTORS

WATER-QUALITY UNITS

Abbreviated water-quality units used in this report: Chemical concentrations, water temperature, and

specific conductance are given in metric units. Chemical concentration of constituents in solution or

suspension is given in milligrams per liter (mg/L) or micrograms per liter (μg/L). Milligrams per liter

is a unit expressing the concentration of chemical constituents in solution as weight (milligrams) of

solute per unit of volume (liter) of water. One thousand micrograms per liter is equivalent to one milligram per liter. Concentrations of sediment-quality constituents are expressed in parts per million

(ppm) by weight. Bacteria densities are expressed as number of colonies per 100 milliliters of water

(col/100 ml).

ABBREVIATIONS

BMP Best management practice

EMC Event mean concentration

SSC Suspended-sediment concentration

PZF Point of zero flow

RPD Relative percent difference

MRL Minimum reporting level

NTU Nephelometric turbidity units

μS/cm Microsiemens per centimeter

Multiply By To obtain

cubic feet per second (ft3/s) 0.02832 cubic meters per second

foot (ft) 0.3048 meter

foot per hour (ft/h) 0.3048 meter per hour

gallon (gal) 3.785 liter

inch (in.) 2.54 centimeter (cm)

inch (in.) 25.4 millimeter (mm)

inch (in.) 25,400 micron (mm)

mile (mi) 1.606 kilometers

square feet (ft2) 0.0929 square meters

ton 907.2 kilogram (kg)

Temperature in degrees Celsius ( ̊C) can be converted to 

degrees Fahrenheit ( ̊F) as follows:  ̊F=1.8 ̊C+32

Ab

Effectiveness of Three Best 

Management Practices for 

Highway-Runoff Quality along the 

Southeast Expressway, 

Boston, Massachusetts

By Kirk P. Smith

Abstract

Best management practices (BMPs) near 

highways are designed to reduce the amount of 

suspended sediment and associated constituents, 

including debris and litter, discharged from the 

roadway surface. The effectiveness of a deepsumped hooded catch basin, three 2-chambered 

1,500-gallon oil-grit separators, and mechanized 

street sweeping in reducing sediment and associated constituents was examined along the 

Southeast Expressway (Interstate Route 93) in 

Boston, Massachusetts. Repeated observations 

of the volume and distribution of bottom material 

in the oil-grit separators, including data on particle-size distributions, were compared to data 

from bottom material deposited during the initial 

3 years of operation. The performance of catchbasin hoods and the oil-grit separators in reducing 

floating debris was assessed by examining the 

quantity of material retained by each structural 

BMP compared to the quantity of material retained 

by and discharged from the oil-grit separators, 

which received flow from the catch basins. 

The ability of each structural BMP to reduce 

suspended-sediment loads was assessed by 

examining (a) the difference in the concentr

of suspended sediment in samples collected 

taneously from the inlet and outlet of each B

and (b) the difference between inlet loads a

outlet loads during a 14-month monitoring 

for the catch basin and one separator, and a 

month monitoring period for the second sep

The third separator was not monitored cont

ously; instead, samples were collected from 

during three visits separated in time by seve

months. Suspended-sediment loads for the e

study area were estimated on the basis of th

term average annual precipitation and the e

mated inlet and outlet loads of two of the se

tors. The effects of mechanized street sweep

were assessed by evaluating the differences 

between suspended-sediment loads before a

after street sweeping, relative to storm prec

tion totals, and by comparing the particle-si

distributions of sediment samples collected 

the sweepers to bottom-material samples co

from the structural BMPs. A mass-balance 

calculation was used to quantify the accurac

the estimated sediment-removal efficiency f

each structural BMP. The ability of each str
2 Effectiveness of Three Best Management Practices for Highway-Runoff Quality along the Southeast Expressway, Boston

BMP to reduce concentrations of inorganic and 

organic constituents was assessed by determining 

the differences in concentrations between the 

inlets and outlets of the BMPs for four storms. The 

inlet flows of the separators were sampled during 

five storms for analysis of fecal-indicator bacteria. 

The particle-size distribution of bottom 

material found in the first and second chambers of 

the separators was similar for all three separators. 

Consistent collection of floatable debris at the 

outlet of one separator during 12 storms suggests 

that floatable debris were not indefinitely retained.

Concentrations of suspended sediment 

in discrete samples of runoff collected from the 

inlets of the two separators ranged from 8.5 to 

7,110 mg/L. Concentrations of suspended sediment in discrete samples of runoff collected from 

the outlets of the separators ranged from 5 to 

2,170 mg/L. The 14-month sediment-removal efficiency was 35 percent for one separator, and 28 

percent for the second separator. In the combinedtreatment system in this study, where catch basins 

provided primary suspended-sediment treatment, 

the separators reduced the mass of the suspended 

sediment from the pavement by about an additional 18 percent. The concentrations of suspended 

sediment in discrete samples of runoff collected 

from the inlet of the catch basin ranged from 32 to 

13,600 mg/L. Concentrations of suspended sediment in discrete samples of runoff collected from 

the outlet of the catch basin ranged from 25.7 to 

7,030 mg/L. The sediment-removal efficiency for 

individual storms during the 14-month monitoring 

period for the deep-sumped hooded catch basin 

was 39 percent.

The concentrations of 29 inorganic constituents in bottom sediments were typically higher 

for the size fraction less than 0.062 mm in diameter. Concentrations of total organic carbon (TOC) 

were similar for the size fraction less than 0.062 

mm in diameter and the fraction greater tha

2.00 mm in diameter. Concentrations of tot

yaromatic hydrocarbons (PAHs) and polych

nated biphenyls (PCBs) were larger in the fr

greater than 2.00 mm in diameter than in th

fractions less than 2.00 mm in diameter. Sin

PAHs and PCBs are commonly associated w

TOC (including organically coated sedimen

believed that the PCB and PAH concentrati

the solid fraction less than 0.062 mm in dia

were similar to the concentrations in the sol

tion greater than 2.00 mm in diameter, if no

greater because of the effects of the surface 

The estimated annual suspended-sedi

load for the entire study area was about 29,0

Approximately 24,000 kg discharged direct

Malibu Beach and Tenean Beach embayme

and the remaining 5,000 kg discharged to th

surface. These loads do not include an estim

2,000 kg of suspended sediment retained by 

five oil-grit separators in the area.

Mechanized street sweepers were use

the pavement three times during the study. S

ples of sweepings were collected each time 

analysis of particle size. The first mechaniz

street sweeping had no observable effect on 

quent storm loads of suspended sediment. F

ing the second sweeping, a net increase of t

suspended-sediment load was observed at o

tion and a net decrease of the suspended-se

load was observed at the second station. Th

effects, however, were only temporary. The 

time the highway was swept was after conti

monitoring was terminated. The particle-siz

distribution in sweeper samples for the size 

tion less than 4 mm in diameter was similar 

the particle-size distribution in bottom sedim

the catch basin. The concentration of partic

greater than 0.5 mm in diameter was higher 

sweeper samples than in samples from the 
Introd

separators, so the sweepers were successful in 

removing the larger particles. Because the highway lacks curbing that would provide a physical 

boundary to trap debris and sediment, and the 

equipment was inefficient in trapping particles less 

than 0.062 mm in diameter, pavement sweeping 

provided few water-quality benefits for the 

Southeast Expressway.

The primary factor controlling the efficiency 

of each structural BMP in removing suspended 

sediment was retention time. Examination of constituent-sediment relations suggests that the retention time for many highway-related constituents 

was short; these constituents either were dissolved 

and not subject to treatment by simple gravity 

separation, or were associated with particles less 

than 0.062 mm in diameter, which commonly 

passed through the BMPs. Thus, the potential 

effectiveness of the separators and the catch basins 

to reduce loads of inorganic and organic constituents was much less than their ability to reduce 

loads of suspended sediment.

The average relative percent difference 

(RPD) between concentrations of trace metals in 

stormwater samples from the inlets and the outlets 

of the separators ranged from 15 to 30 percent. 

The average RPD for concentrations of organic 

constituents was commonly less than about 10 percent and negative in several cases. The separators 

did not affect the concentrations of dissolved 

solids as they passed through their chambers. The 

average RPD between the event mean concentrations for trace metals in samples collected from 

the inlet and outlet of the catch basin during 

storms was about 25 percent. The average RPD for 

concentrations of organic constituents was typically less than 20 percent and even negative in 

several cases, except for oil and grease, which 

was near 30 percent. The observed ranges of the 

RPDs for both types of BMPs were probabl

larger than the actual ranges because the pa

size and concentration of suspended sedime

sampled in the BMP inflows during the fou

storms introduced a bias in favor of higher 

concentrations.

Concentrations of fecal and Enteroco

bacteria were found throughout the storms 

inlets of the two continuously monitored se

tors; this result indicated that the pavement 

washoff process was inefficient or that there 

continuous source of bacteria in the drainag

The efficiency of the structural BMPs tested 

study in reducing fecal-indicator bacteria co

trations was not quantified; each BMP cham

likely to retain a quantity of fecal-indicator 

ria proportional to its storage volume after a 

Removal of bacteria from the BMP is depen

on how well the bacteria survive until the n

storm and the potential for bacterial export 

the next storm. 

INTRODUCTION

Suspended particulate matter transported 

roadway surfaces represents one of the most sub

sources of non-point source pollution in highwa

runoff (Young and others, 1996). In addition to 

ing turbidity and depositional loading, suspende

ment can retain and transport other pollutants to 

receiving water bodies. Roadway suspended-so

loads may be reduced by diverting storm flows t

various structural end-of-pipe devices or by rem

particulate matter from roadway surfaces prior 

runoff transport (for example, source control). T

effectiveness of these best management practice

(BMPs) is limited by the general lack of inform

about the site-specific size distribution and quan

the source material.
4 Effectiveness of Three Best Management Practices for Highway-Runoff Quality along the Southeast Expressway, Boston

The U.S. Geological Survey (USGS), in cooperation with the Federal Highway Administration and the 

Massachusetts Highway Department (MassHighway), 

began a study in November 1998 to determine the 

effectiveness of current BMPs in reducing suspendedsolid loads and related constituents along the Southeast 

Expressway (Interstate Route 93) in Boston, Massachusetts. The Southeast Expressway is typical of 

heavily used highways within urban and industrialized 

areas, although it passes through the coastal zone 

watersheds of Dorchester Bay in Boston. In 1994, the 

Expressway was modified to provide a moveable “zipper barrier” to increase traffic flow in the peak direction. This zipper barrier consisted of cast-concrete 

barriers connected to one another and mechanically 

moved by a specialized machine to create an additional 

travel lane. During this time, in an effort to remove oils 

and grit (sand- and gravel-size particles) from highway 

runoff, five off-line oil-grit separators (commonly 

referred to as water-quality inlets) were integrated 

into the primary drainage system of the highway 

adjacent to Dorchester Bay.

The BMPs examined in this study include a 

deep-sumped hooded catch basin, three 1,500-gal offline oil-grit separators, and mechanized sweeping. 

The effectiveness of each structural BMP was estimated by monitoring the quality and quantity of 

stormwater at the inlet and outlet of each device. At 

the end of the monitoring period, each device was 

drained and the captured material was measured and 

quantified. Street-sweeping effectiveness was evaluated 

by examining the differences in suspended-sediment 

loads in highway runoff before and after storms relative 

to precipitation amounts and antecedent periods, and 

by comparing the size distribution of sediment collected from the street sweeper to bottom sediments 

collected in the catch basin and the separators. These 

monitoring results will provide state and local highway 

planners with specific information regarding the current quality and quantity of highway runoff from 

major urban highways in the northeastern United 

States, and the scientific basis for future consideration 

and application of these BMPs. Monitoring methods 

developed during this study may be useful for assessing 

the effectiveness of new BMPs.

This report describes the effectiveness of 

BMP along the Southeast Expressway in reduci

pended-sediment loads, debris loads, and chemi

biological loads in highway runoff. It also descr

physiochemical characteristics of structural BM

bottom materials, the estimated suspended-solid 

for the study area, and documents the monitorin

ods by which the effectiveness of each BMP wa

mated. These results are based on highway-runo

collected from November 1998 through June 20

Description of Study Area and 

Highway-Drainage Systems

The study area comprised 2.2 mi of Inter

from the Neponset River to Savin Hill in Bosto

(fig. 1). This section of highway, including ram

covers about 35 acres. About 1.5 mi of this eigh

highway crosses the Neponset drainage basin a

0.7 mi crosses the Boston Harbor Coastal subba

Within the study area, 209 catch basins provide 

mary treatment for highway stormwater runoff; 

included is one 3-chamber 4,500-gal off-line oi

separator and four 2-chamber 1,500-gal off-line 

separators. Highway runoff collected by the cat

basins is either discharged to the local land surf

to a separator through a concrete or steel drainag

Highway runoff from 26.4 acres discharges thro

structural BMPs to the embankment along the M

Beach and Tenean Beach embayments. Runoff 

the remaining 8.2 acres infiltrates into the groun

Catch basins are circular concrete contain

below the highway with steel grates at the pave

surface. The sumps (that is, storage area below 

outlet pipe) of 184 catch basins are 4 ft deep, an

remaining 25 are 3 ft deep. Hinged cast-iron ho

intended to retain floatable debris at the water s

are loosely fitted over the sump outlet of most c

basins. The hoods encapsulate the entire outlet o

and extend about 0.5 ft below the bottom of the 
Introd

739

136

Southeast

Expressway

U.S. Route

1

Interastate

93

749

0 1/2 1 MILE

0 .5 1 KILOMETER

739 STATION LOCATION

 AND NUMBER

EXPLANATION

71o 71 02'30" o03'00"

42o18'30"

42o17'00"

Orthophoto source MassGIS, EOEA, 1995

STUDY AREA

MAP AREA SHOWN 42o30'

0 50 KILOMETERS

0 50 MILES 

MASSACHUSETTS

73o00' 71o00'

70o00'

41o30'

BOSTON

BOSTON

BROOKLINE

CAMBRIDGE

SOMERVILLE

QUINCY

DEDHAM MILTON

NEEDHAM

NEWTON

WATERTOWN

WALTHAM

BELMONT

MEDFORD

ARLINGTON

LEXINGTON

EVERETT

CHELSEA

REVERE

MALDEN

WINTHROP

BOSTON 

(DOWNTOWN)

South Boston

U.S. Naval Annex

Logan Airport

Neponset River

Quincy Bay

Boston

Harbor

ORTHOPHOTO

TOWNS IN VICINITY

Charles River

Dorchester Bay

Mystic River

Figure 1. Study area where best management practices were tested, Southeast Expressway, Boston, 

Massachusetts.
6 Effectiveness of Three Best Management Practices for Highway-Runoff Quality along the Southeast Expressway, Boston

Oil-grit separators, large cast-concrete containers 

subdivided by one or more baffles, are buried next to 

the highway. They provide additional treatment of 

stormwater runoff by capturing suspended particulate 

matter, oil and grease, and floatable debris (fig. 2). A 

hood or an inverted elbow was not installed over the 

outlet of the second chamber of the separators. A baffle 

separated the primary chamber from the secondary 

chamber, and contained three circular 12-in. outlets 

1.5 ft from the chamber floor. Each separator included 

a bypass pipe that carried flow past the device during 

intense runoff by use of a diversion weir placed near the 

inlet of the separator. Although this design feature allows 

untreated stormwater to bypass the separator, it theoretically prevents extreme flows from flushing captured 

materials from the separator. Stormwater runoff from as 

many as 6 to 26 catch basins was diverted through the 

five separators. Highway runoff diverted through the 3-

chamber 4,500-gal separator and two 2-chamber 

1,500-gal separators is discharged to the embankments 

of Malibu Beach and Tenean Beach embayments, 

and runoff from the other two 2-chamber 1,500-gal 

separators is discharged to land near a small tributary 

of the Neponset River. 

The highway does not have a breakdown lane; 

however, it does have three emergency pull-off areas. 

Beyond the edge of pavement, which begins beneath 

the guard rail, the ground consists of loosely packed 

sandy-loam with sparse vegetation cover. Granite curbstone lines the ramps; but in most cases, there is either 

no curb along the highway, or the curb is buried and the 

material at the edge of the pavement is able to erode 

onto the roadway during storms. Concrete barrier walls 

are installed on overpasses and separate the pavement 

from the areas with steep embankments and curves. 

The three 1,500-gal separators evaluated during 

the study were designated sites 136-01, 739-01, and 

749-01 (fig. 3). The first three digits refer to the surveyed highway reference points (stations). The outflow 

and inflow monitoring and sampling point desig

of each separator consisted of the same prefix fo

by –02 and –03, respectively. The deep-sumped 

catch basin is within the drainage area of the se

136-01 and was designated as site 136-06. The 

and inflow monitoring and sampling point desig

of the catch basin consisted of the same prefix fo

by –04 and –05, respectively. All drainage pipes 

in diameter and accessible through manholes. Th

separators are located about 5 ft from the right 

pavement. Site-specific details for each structur

are listed in table 1. The greatest difference betw

the drainage areas of the five separators is the s

the number of catch basins. Only the separators 

monitoring sites 136 and 739 were selected for 

uous monitoring because the inlet manhole for 

grit separator at station 749 is in a travel lane, a

remaining two are periodically subjected to tida

from Dorchester Bay. The catch basin at site 13

selected for evaluation because the outlet pipe i

lated from the combined drainage infrastructure

the data from samples at this outlet could be co

to data from samples collected from the separat

Acknowledgments

Henry L. Barbaro of the Environmental D

and Thomas R. Lemisz of the Granite Avenue M

nance Office provided planning and logistical s

for MassHighway during this study, including p

traffic control, structural BMP cleaning, and str

sweeper sample collection. Paul D. Capel of the 

developed a feasible and cost-effective sample-p

ing method for trace organic and inorganic cons

that was adapted for automatically collected hig

runoff samples.
Introduction 7

Coarse grit

Floating debris

4 feet

4 feet

4 feet

10 feet

Manhole

Inlet

Inlet

Outlet

Diversion

weir

Diversion

weir

Outlet

Highflow-bypass

Highflow-bypass

Hood

Grate

Point of zero flow

From other catch basins

Deep-sumped From other catch basins

hooded 

catch basin

Catch basin drainage junction

Catch basin drainage junction

Manhole cover

Manhole cover

Grate

Highway

pavement

Chamber 1

Chamber 2

Fill embankment

Coarse grit

and debris Fine grit

and

debris

Highway-runoff water

Manhole covers

Baffle

Baffle

Chamber 1

Chamber 2

Stormwater pipe

Stormwater pipe

Edge of road

Figure 2. Schematic section of a deep-sumped hooded catch basin and a 1,500-gallon off-line oil-grit separator.
8 Effectiveness of Three Best Management Practices for Highway-Runoff Quality along the Southeast Expressway, Boston

HALLET STREET

HIGH FLOW

BYPASS

0 100

0 30 60 METER

200 FEET

A.

B.

C.

Station 749

Station 739

Station 136

EXPLANATION

CATCH BASIN

EDGE OF ROAD

MANHOLE

MAIN EXPRESSWAY

 THOROUGHFARE 

12-INCH STORM PIP

RISE WHERE STRE

 RUNOFF DIVIDES

RUNOFF DIRECTIO

 TOWARD THE

 CATCH BASINS

FLOW WITHIN THE

 STORMWATER

 PIPES

1,500 GALLON

OFF-LINE SEPARATOR

(749-01)

HIGH FLOW

BYPASS

HIGH FLOW

BYPASS

1,500 GALLON

OFF-LINE SEPARATOR

(739-01)

1,500 GALLON

OFF-LINE SEPARATOR

(136-01)

1,500 GALLON OFF-

 SEPARATOR

ON-OFF RAMPS

136-06

Figure 3. Actual drainage area of stations (A) 749, (B) 739, and (C) 136, along the Southeast Expressway, Boston, 

Massachusetts.
Methods for Continuous Monitoring of Highway Dra

METHODS FOR CONTINUOUS 

MONITORING OF HIGHWAY 

DRAINAGE

Automatic-monitoring techniques were used to 

characterize the temporal and spatial variability in 

water quality through two 1,500-gal separators and one 

deep-sumped hooded catch basin. Monitoring sites 136 

and 739 were continuously monitored from April 1999 

through June 2000, and August 1999 through June 

2000, respectively. At each site, instruments automatically collected water samples and measured precipitation, air temperature, water level, flow velocity, 

turbidity, specific conductance, and water temperature 

in the structural BMP. Flow-proportional samples, 

which represent equal volumes of runoff, were collected for the analysis of suspended-sediment concentrations from the inlet and the outlet of each structural 

BMP at stations 136 and 739 during their respective 

monitoring periods. Flow-proportional composites 

were collected from the inlet and the outlet of each 

structural BMP during four storms and were analyzed 

for the event mean concentration (EMC) of chemical 

constituents. Discrete and EMC samples analyzed for 

concentrations of suspended sediment were used to 

estimate suspended-sediment loads and determine the 

effectiveness of each BMP in reducing suspended 

sediment and chemical concentrations. The frequency 

and spatial occurrence of fecal-indicator bacteria in 

highway runoff was determined by analyzing flowproportional samples collected at the inlets of the two 

separators. Particles greater than 6 mm in diam

were collected at the outlet of station 739 durin

storms to determine how effectively the separat

were retaining large particles, particularly floata

debris. Precipitation was measured to estimate t

runoff of the drainage area for each station. Air 

ature was measured to determine whether the pr

tion was rain or snow. Water-level and flow-vel

data were used to estimate discharge to and from 

structural BMPs. Turbidity was investigated as 

gate for the concentration of suspended sedime

Water temperature was measured to correct con

ity values to 25 ̊C. Small saline flows containin

concentrations of dissolved solids associated wi

ing compounds commonly used during the win

maintenance period caused large changes in the 

cific conductance of the water in each separator

increase in the concentration of dissolved solids 

increased the density of the water and introduce

to the measured water levels. A linear correctio

mated from measurements of specific conducta

was used to correct the water-level measuremen

Just prior to the monitoring period, each 

tural BMP was drained and cleaned with a vacu

truck, and visually inspected to ensure that the 

bers were clean enough for an accurate mass ba

calculation at the end of the study. The quantity 

bottom material retained in separators 136-01 a

749-01 was assessed three times, and the quant

bottom material retained in separator 739-01 w

assessed four times during the project. Because 

Table 1. Location and construction properties of selected structural best management practices, Southeast Expressw

Boston, Massachusetts

[Latitude and longitude: In degrees, minutes, and seconds. BMP, best management practice; ft, foot; na, not applicable; --,no data]

Station 

identifier

Latitude

° ′ ′′

Longitude

° ′ ′′

Total drainage area 

(acres)

Isolated 

shoulder 

perimeter 

(percent)

Number

of catch 

basins

Median

catch basin

drainage area

(acres)

Diversion 

weir

height (ft)

Type of BM

739-01 42 16 47 71 02 47 1.48 22 12 0.12 0.7 oil-grit separator

749-01 42 16 56 71 02 42 .73 6 6 .12 -- oil-grit separator

136-01 42 17 45 71 02 45 1.11 10 8 .10 .5 oil-grit separator

136-06 42 17 45 71 02 45 .23 6 1 na na deep-sumped ho

catch basin
10 Effectiveness of Three Best Management Practices for Highway-Runoff Quality along the Southeast Expressway, Bosto

catch basin 136-06 was in a highway travel lane, it was 

not practical to routinely measure the quantity of 

bottom material. This BMP was assessed just once, at 

the end of the monitoring period. Samples for particle 

size and visual analysis were collected twice from each 

of the three separators and once from the catch basin to 

compare with water-quality samples and street-sweeper 

samples. Samples of bottom material were colle

and analyzed for concentrations of chemical co

ents twice at each of the three separators to dete

chemical-sediment relations. Street-sweeper sam

were collected and analyzed for particle size thr

times during the project. The quantity and type 

samples collected are summarized in table 2.

1Two or more particle size ranges analyzed. 

Table 2. Quantity and type of samples collected, and location of water level, water-velocity, water-quality, meteorology

physical measurements made at each structural best management practice, Southeast Expressway, Boston, Massach

[Sample quantities do not include quality-assurance samples; C, continously monitored; (x), number of months]

Measurement or

sample location Water level Velocity

Water

temperature

Air

temperature

Specific

conductance Turbidity 

Station 136................................................... -- -- -- C(14) -- -- 

Oil-grit separator 136-01 (storage).............. C(14) -- C(14) -- C(14) -- 

Oil-grit separator 136-02 (outlet) ................ C(14) C(14) C(14) -- C(14) C(14) 

Oil-grit separator 136-03 (inlet) .................. -- -- C(14) -- C(14) C(14) 

Oil-grit separator 739 (bypass).................... C(14) C(14) -- -- -- -- 

Catch basin 136-04 (outlet) ......................... -- -- -- -- -- -- 

Catch basin 136-05 (inlet) ........................... -- -- -- -- -- -- 

Catch basin 136-06 (sump).......................... C(14) -- -- -- -- -- 

Station 739................................................... -- -- -- -- -- -- 

Oil-grit separator 739-01 (storage).............. C(10) -- C(10) -- C(10) -- 

Oil-grit separator 739-02 (outlet) ................ -- -- C(10) -- C(10) C(10) 

Oil-grit separator 739-03 (inlet) .................. C(10) C(10) C(10) -- C(10) C(10) 

Oil-grit separator 739 (bypass).................... C(10) C(10) -- -- -- -- 

Oil-grit separator 749-01 (storage).............. -- -- -- -- -- -- 

Measurement or

sample location

Suspended 

sediment

Water 

quality Bacteria

Bottommaterial 

quantity

Bottommaterial

particle size

Bottommaterial

quality

co

Station 136................................................... -- -- -- -- -- -- 

Oil-grit separator 136-01 (storage).............. -- -- -- 3 2 12 

Oil-grit separator 136-02 (outlet) ................ 379 4 -- -- -- -- 

Oil-grit separator 136-03 (inlet) .................. 379 4 4 -- -- -- 

Oil-grit separator 739 (bypass).................... -- -- -- -- -- -- 

Catch basin 136-04 (outlet) ......................... 314 4 -- -- -- -- 

Catch basin 136-05 (inlet) ........................... 243 4 -- -- -- -- 

Catch basin 136-06 (sump).......................... -- -- -- 1 1 -- 

Station 739................................................... -- -- -- -- -- -- 

Oil-grit separator 739-01 (storage).............. -- -- -- 4 2 12 

Oil-grit separator 739-02 (outlet) ................ 369 4 -- -- -- -- 

Oil-grit separator 739-03 (inlet) .................. 465 4 5 -- -- -- 

Oil-grit separator 739 (bypass).................... -- -- -- -- -- -- 

Oil-grit separator 749-01 (storage).............. -- -- -- 3 2 12 
Methods for Continuous Monitoring of Highway Drai

Design of Highway-Drainage 

Monitoring Stations

Instrumentation shelters with trap doors were 

installed over the distribution manhole next to each 

separator. Trap doors provided protective entry to the 

drainage-distribution system for probe and sample-line 

maintenance. Sites 136-01 and 136-06 were monitored 

from the same location and instrument bank. The 

instrumentation consisted of a Campbell Scientific Inc. 

(CSI) 23X datalogger as the measurement, control, and 

data-storage module. Because electric and phone lines 

were not readily available, two 60-amp hour batteries 

recharged by 30-watt solar panels were used to power 

the controller and other instruments. A CSI VS1 voicedata telephone modem and a cellular phone were used 

for telecommunications. The datalogger measured precipitation from an 8-in. Texas Electronics, Inc. tipping 

bucket rain gage and air temperature from a CSI 107 

probe mounted at a height of 9 ft above ground surface. 

A CSI precipitation adapter was installed on each rain 

gage during the winter months to measure snow and ice 

quantities, as well as rainfall. Water level was measured 

by a KPSI series 173 submersible pressure transducer 

mounted within each structural BMP near the outlet 

and 2 ft below the point of zero flow (PZF). The PZF 

water level was controlled by the height of the outlet 

pipes (fig. 2). Two Marsh McBirney, Inc., submersible 

electromagnetic pressure sensors measured water 

velocity and level within each separator bypass pipe 

and the inlet of station 739 and the outlet pipe of station 

136. 

Water level, air temperature, and precipitation 

were measured at 1-minute intervals. Water-level measurements were used to determine whether to activate 

sensors for flow and water quality. During periods of 

little or no flow, when water level in the separator or 

catch basin was less than 0.02 ft above the PZF and 

there was no precipitation, all sensors were activated, 

measured, and recorded on a two-hour basis; during 

storms, however, the frequency of data recording and 

instrument activation for all sensors increased to 1-

minute intervals. The dataloggers were programmed 

with these intervals to maximize the information about 

changes in stage, velocity, precipitation intensity, and 

water quality, and for the collection of water samples, 

while preventing collection of excess data at times of 

little or no flow. Data were usually retrieved via modem 

every two days.

Measurement of Discharge

Discharge measurements did not alter the 

ity of the structural BMPs, or create artificial bac

conditions that could prevent suspended solids 

bed-load materials from either entering or disch

from the structural BMPs. Continuous measure

of water level in each structural BMP indicated 

the water level generally remained at or near th

thus, it was assumed that any amount of inflow 

including bypass flow) displaced an equal amou

outflow. 

Instantaneous discharge to and from the a

ated separators was calculated by one of two m

During higher flows, an integrated electromagn

velocity and level sensor measured pipe-flow ve

and water level. Using the velocity and level me

ments and the physical dimensions of the measu

location, a flowmeter calculated discharge on th

of the cross-sectional area of runoff at a given s

of pipe and the associated mean velocity. Flowm

measurements and flow calculations were trans

to, and recorded by, the datalogger. An integrate

tromagnetic velocity and level sensor was insta

the bypass pipe of each separator and in the inle

tion 739 and in the outlet pipe of station 136. S

placement differed between the two sites becau

differences in the drainage-system construction

installation, each flowmeter was calibrated to si

specific conditions on the basis of a known qua

of flow. Calibrated flow, created by pumping wa

with a 9,600-gal/hr centrifugal pump, was disch

upstream of the sensor location. Pump flow was 

sured by a Data Industrial flow sensor (series 20

inserted into an 8-ft long, 4-in.-diameter polyvin

ride (PVC) pipe connected to the pump dischar

addition to this calibration method and prior to 

monitoring period, instantaneous stormwater flo

ter measurements were compared to flow measu

ments made simultaneously from a 12-in. Thelm

volumetric weir in conjunction with a WaterLog 

(H350-Lite) pressure transducer and a pneumat

bubble regulator upstream of the integrated sens

maximum difference between the two methods 

flow range of 0.1 to 0.45 ft3/s was 0.04 ft3/s. W

water depth at the flow sensor was less than 0.1 

values calculated by the flowmeter were not con

reliable because the velocity sensor was not ful

submersed.
12 Effectiveness of Three Best Management Practices for Highway-Runoff Quality along the Southeast Expressway, Bosto

A second method to measure flow was needed 

during low flows because the flowmeter was not capable of calculating discharge when the integrated sensor 

lost contact with the water surface. Therefore, a 

stage/discharge relation based on the water level within 

the second chamber of the separator was used to compute flows. Each stage/discharge relation was developed during the pre-monitoring period by monitoring 

water levels in each separator while simultaneously 

monitoring flow with the volumetric weir and associated equipment. Volumetric measurements made from 

the separator outlet pipe were also used to develop and 

test the low-end stage/discharge rating.

Inflow to the catch basin was calculated by 

applying a stage/discharge relation to continuous 

water-level measurements made in the sump of the 

catch basin. This relation was developed by simultaneously measuring pump flow from the two 

9,600-gal/hr centrifugal pumps, measuring flow from a 

12-in. weir located downstream of the catch basin, and 

measuring catch-basin-sump level. Paired stage and 

discharge values were produced from a series of waterlevel measurements made after pump flow, weir flow, 

and catch-basin-sump level stabilized at multiple 

pumping rates over the range of the pumps. This process was repeated until both pumps were at the maximum setting. After stabilization occurred at the 

maximum setting, the process was repeated to the start 

point. The stage/discharge relation was based on 21 

discrete discharge measurements and mathematically 

extended above the greatest flow rate (about 0.25 ft3/s). 

The resultant stage/discharge relation sufficiently covered 83 percent of the peak discharges during the 

monitoring period. 

Measurements of Turbidity, 

Specific Conductance, and 

Water Temperature

To reduce systematic error (error associated with 

sensor drift and fouling) and increase the ability to 

make measurements at water levels less than the physical submersion limit of the probes, a single Global 

(model WQ 700) turbidity sensor, and a single C

(model 247) integrated specific conductance an

temperature probe were used to measure alterna

pump-activated streams of water from the inflow 

outflow of each structural BMP. The respective 

were installed in a self-draining-flow cell equip

with a debubbler pipe. A pipe tee combined the 

peristaltic-pump discharge tubes; mechanical cl

of the silicon tubing in the pump head prevente

flow through the quiescent pump. A Data Indus

flow sensor (series 4000) was used to measure i

tent flow from the two peristaltic pumps (ISCO 

110). Pump intakes were mounted next to the a

matic sampler intakes for sample uniformity. Pu

transport velocities were similar to those in the 

matic samplers; therefore, in situ turbidity meas

ments in pumped water were technically simila

those in water samples collected by the automa

samplers. 

During the first 2 hours of a runoff event, 

was greater than or equal to 0.02 ft3/s, the datal

was programmed to start a 2-minute cycle: the 

peristaltic pump was activated for a period of on

half minutes, pump flow was measured and reco

the inline flow meter, and specific conductance, 

temperature, and turbidity were measured and re

at the end of the pumping interval. The pumpin

val provided enough time to exchange the volum

water within the flow cell several times. The flo

was allowed to drain during the final 30 second

2-minute cycle. The cycle was then repeated by 

of the outlet peristaltic pump. Alternating 2-min

cycles of measurements of specific conductance

temperature, and turbidity were made for a peri

hours; thereafter, cycles of measurement were m

less frequently and proportional to flow to redu

tery-power consumption during extended opera

An example of water quality and stage data col

from this system for a separator at station 739 is 

in figure 4.
Methods for Continuous Monitoring of Highway Drai

0

30

60

90

120

150

180

210

0

50

100

150

200

250

300

350

0

0.2

0.4

0.6

0.8

1

1.2

6:00 7:12 8:24 9:36 10:48 12:00 13:12 14:24 15:36 16:48 18:00 19:12 20:24 21:36 22:48 0:00 1:12 2:24

TIME OF DAY

INFLOW

OUTFLOW

INFLOW

OUTFLOW

TURBIDITY, IN NEPHELOMETRIC

 TURBIDITY UNITS

SPECIFIC CONDUCTANCE, 

IN MICROSIEMENS PER CENTIMETER STAGE, IN FEET

STAGE

Figure 4. Specific conductance, turbidity, and stage measured at highway runoff monitoring station 739, 

September 10–11, 1999, Southeast Expressway, Boston, Massachusetts.
14 Effectiveness of Three Best Management Practices for Highway-Runoff Quality along the Southeast Expressway, Bosto

COLLECTION AND 

ANALYSIS OF SAMPLES

Highway-runoff samples for the analysis of suspended-sediment concentration, water chemistry, and 

bacteria were collected automatically with flowproportional methods at each structural BMP. 

Sampling-equipment setup, however, varied with 

respect to the constituent sampled. Large debris 

entrained in highway runoff was composited in a collection structure at the outlet of a separator. Bottom 

material retained in the structural BMPs was volumetrically assessed and sampled several times during the 

study. Samples of bottom material were analyzed for 

particle size, density, and chemical concentrations. 

Samples of sediment collected from street sweepers 

in the vicinity of the highway test sites were analyzed 

for particle size. The contents of the bottom material, 

street sweeper, and debris samples were quantified in 

identifiable categories. 

Automatic Sample 

Collection

Highway-runoff samples for the analysis of 

suspended-sediment concentration and water chemistry 

were collected at the inlet and outlet of each structural 

BMP by an automatic sampler (ISCO model 6700) 

controlled by a datalogger. The first sample was collected when flow exceeded 0.02 ft3/s and subsequent 

samples were collected at flow-proportional intervals. 

Maximum vertical-sampling distance from the sampler-pump head to any fixed sampling point was about 

10 ft. All sampler lines were mounted in a sloping 

manner when possible to allow for the complete purging and draining of sample water between samples. The 

lengths of the sampler lines ranged from 12 to 30 ft for 

the separators, and were 24 and 59 ft long for the inlet 

and the outlet of the catch basin, respectively.

Sampler intakes were fixed to static mixers at 

each sampling point for all sampling locations, except 

for the catch-basin inflow (fig. 5). The purpose of the 

static mixer was to provide a secure and consistent 

mount for the sampler intake, reduce transport velocity, 

and to provide agitation to produce a sample that represented the average concentration of suspended sediment. Sampler intakes were oriented in a horizontal 

and downstream direction. This configuration 

minimizes debris accumulation by forming a sm

eddy that captures sand particles at the intake, an

allows the sampler to collect a more representat

sample of the coarse load (Edwards and Glysso

1999). The static mixers were constructed from 

0.5-in. marine-grade homogenous polymer shee

consisted of two semicircular plates 1.2 in. high 

center. Two polyvinylidenefluoride (PVDF) 0.5

bulkhead-compression fittings were attached to 

side of the first plate 1.2 in. from the center and 

from the bottom. The second plate had two sem

lar 0.7-in. holes in parallel with the bulkhead fit

prevent sediment accumulation between the two 

and was mounted about 4 in. behind the primar

The structure for stormwater sample colle

was mounted below the grate in the catch basin 

was designed to concentrate stormwater through 

common point from which the sample was colle

The structure was constructed from a 0.5-in. mar

grade homogenous polymer sheet and was desi

similar to the collection box described by Spang

and Niemczynowicz (1992). A 1.25-in. PVDF te

located at a common drainage point on the bottom 

structure. A free-swinging flapper valve was atta

one end of the tee. The sampler line was inserted 

a compression fitting at the opposite end of the te

parallel to the direction of flow. The end of the sa

tube was positioned approximately midway betw

the tee and the flapper valve. The flapper valve c

a small amount of backpressure enabling sample 

collection at flows as low as 0.02 ft3/s. 

Suspended Sediment

Automatic samplers to collect suspended 

ment held 24 1-L plastic bottles attached to sam

lines made of 0.5-in. polyethylene tubing. Discr

samples were generally collected on one of thre

proportional thresholds based on the volume of 

structural BMP. Once the accumulated flow wa

to or greater than the threshold, the automatic s

collected a water sample, and the accumulated 

was zeroed. In general, the threshold for the sec

third, and fourth sample collected from the inle

outlet of the separator was 100 ft3 (1/2 the volu

the device), the threshold for the next 16 sampl

200 ft3, and the threshold for the last four samp

400 ft3. The dataloggers were programmed in th

to maximize the information obtained about the 
Collection and Analysis of Sam

Baffle made of 1/2-inch marine-grade

polymer sheet Static mixing area (capture area)

Intake manifold

(1-inch tall average height)

STATIC MIXER ASSEMBLY

1/2-inch bulkheadcompression fittings

1/2-inch PVDF piping

(intake pipes)

Water flow direction

runoff period and to ensure that samples for the analysis of suspended-sediment concentration were collected throughout the entire storm. During large 

storms, sample bottles were retrieved and replaced as 

needed to characterize the entire storm. The date, time, 

water level, sample number, and sampler response was 

recorded by the datalogger each time a sample was 

triggered. 

Solid-phase concentration values may be determined by the suspended-sediment concentration (SSC) 

or the total suspended solids (TSS) method. Although 

SSC and TSS are often cited interchangeably in the literature to describe the total concentration of suspended 

solid-phase material, the analytical methods differ and 

can produce substantially different results (Bent and 

others, 2000). The SSC method (ASTM, 2000) uses 

standardized procedures and equipment to mea

all of the sediment and the net weight of the wa

sediment mixture to calculate concentration. Th

TSS method (American Public Health Associat

American Water Works Association, and Water 

Pollution Control Federation, 1995) requires an

of a subsample extracted from the original samp

Contrary to the literal description, SSC include

silts, sands, gravels, asphalt particles and other 

surface debris, and organic and synthetic mater

Although analytical uncertainties for the two m

are similar, larger errors can occur during proce

TSS samples because agitation of a sample con

sand-size materials can produce aliquots which 

represent the true sediment concentration (Gray 

others, 2000). Therefore, the SSC method was c

Figure 5. Schematic diagram of a static mixer used in conjunction with the automatic samplers.
16 Effectiveness of Three Best Management Practices for Highway-Runoff Quality along the Southeast Expressway, Bosto

to measure the solid-phase concentrations to provide 

the most accurate assessment of BMP efficiencies. 

Samples were analyzed for SSC and particle size at the 

USGS Kentucky District Sediment Lab (Guy, 1970; 

Sholar and Shreve, 1998).

Water Chemistry

Several changes were made in the sampling 

equipment and programming for the automatic collection of water samples for analysis of inorganic and 

organic constituents. Each automatic sampler was configured to hold one 20-L Teflon-lined plastic bottle. 

The Teflon lining consisted of a double wall Teflon 

pouch manufactured by NOW Technologies and constructed in a clean room without the use of glue or 

adhesives. Automatic sample lines were replaced with 

pre-cleaned 0.5-in. Teflon tubing. The pump-head 

tubing was also exchanged with a pre-cleaned 

replacement and a Teflon discharge tube. Samples were 

collected on a single flow-proportional threshold on the 

basis of the expected volume of runoff, volume of individual samples, and maximum number of sample volumes relative to bottle size. The empty space around 

the sample bottle was packed with ice prior to each 

storm to preserve sample integrity.

A multi-step process was used to clean all wetted 

parts associated with the automatic sampler and the 

processing equipment before collecting trace inorganic 

and organic constituents. The initial cleaning consisted 

of washing the interior and exterior with a phosphatefree laboratory grade soap and tap water, scrubbing 

surfaces with a plastic brush, rinsing with tap water, 

and a final rinse with deionized water. Circulating the 

solution through the tubing with a peristaltic pump 

cleaned the interior of the sampler tubing. Cotton balls 

were forced hydraulically through the tubing to remove 

internal deposits or films that were difficult to remove 

by circulating solution alone. All components were 

dried in a laboratory-circulating oven for a minimum of 

12 hours at 105 ̊C. After the water evaporated and the 

components cooled, they were placed in a large stainless steel pan in a fume hood and immersed in a 1-to-1 

hexane-to-acetone solution. A Teflon diaphragm pump 

was used to circulate the solution through the sampler 

tubing. The components were allowed to soak, with 

occasional agitation, for a period of six hours. After 

appropriately dispensing the waste solution, all components except the tubing were rinsed with a 1-to-1 

hexane-to-acetone solution from a Teflon squee

tle, air-dried in a fume hood over night, and dri

laboratory circulating oven for a minimum of 1

at 60 ̊C. Because the rate of cleaning-solution v

ization was limited within the sampler tubing, t

tubing was purged with purified nitrogen gas fo

approximately 20 minutes and then thoroughly 

with copious amounts of deionized water. The fi

steps involved immersing the components in a 5

percent solution of hydrochloric acid for a perio

hours. The same solution was slowly circulated 

through each sampler tube for 6 hours. All comp

were thoroughly rinsed with deionized water un

specific conductance of the waste rinse water w

that 1 μS/cm. Sample bottles, Teflon lines, pum

tubes, discharge tubes and processing compone

were double-bagged to maintain clean techniqu

Bags were left on the bottles during installation 

subsequent transport. 

Samples were collected and processed ac

to “clean hands-dirty hands” techniques (Wilde 

Radtke, 1999). Samples were processed in the U

Massachusetts District laboratory clean room, u

within 24 hours of the time that collection of th

sample was triggered by the automatic sampler

samples for the analysis of suspended sediment

inorganic and organic constituents were split di

from the Teflon-lined bottle. This method elimi

sample contact with additional processing equip

and reduced the potential for contamination. Su

ples were dispensed under low pressure directly 

the sample bottle with a specialized cap, which 

included a 3.1-mm (inner diameter) Teflon disp

tube, a pressure port, and a relief valve. Compre

nitrogen gas applied to the pressure port filled t

rior area between the bottle wall and the pouch

pressing the pouch and dispensing the sample. 

Homogenization of the sample was accomplish

fastening the bottle to a cradle assembly capabl

rotating 210 degrees. The sample bottle was roc

full 210 degrees at least 20 times at a frequency 

cycle per second prior to dispensing. The rockin

motion was continued throughout dispensing fo

samples except for samples analyzed for dissolv

constituents. Dissolved inorganic constituents w

tered through a 600-cm Gelman capsule filter w

0.45-mm pore size. Dissolved organic carbon w

filtered through an inline Teflon filter holder wi

47-mm silver membrane filter with a 0.45-mm 
Collection and Analysis of Sam

size. All samples were double bagged and stored on ice 

for overnight delivery to the USGS National Water 

Quality Laboratory in Lakewood, Colorado, for chemical analysis (Wershaw and others, 1987; Fishman and 

Friedman, 1989; Fishman, 1993; Fishman and others, 

1994).

Bacteria

Flow-proportional, discrete water samples for 

the analysis of bacteria were collected from a second 

dedicated automatic sampler at the inlet of each separator. Each automatic sampler was configured to hold 

twenty-four 350-mL glass bottles. Sample lines consisted of sterile 0.5-in. silicon tubing. The pump head 

and discharge tubing were pre-cleaned and sterilized. 

Sample bottles were autoclaved and treated with a 15-

percent solution of ethylenediaminetetraacetic acid 

(EDTA) to chelate sample trace-metal concentrations 

that would be potentially toxic to bacteria (American 

Public Health Association and others, 1992). The sampler base was packed with bagged ice prior to each 

storm. Samples for analysis of bacteria were collected 

automatically along with the samples collected for 

analysis of inorganic and organic constituents.

Sequential discrete samples for analysis of fecal 

and Enterococci bacteria were periodically composited 

because the amount of equipment and personnel limited the number of analyses that could be completed 

within the method holding time. The entire aliquot of 

two or more sequential discrete samples was composited into a sterile 2-L bottle. The samples for bacteria 

analysis were processed on the basis of the methods 

described by Myers and Sylvester (1997) and the U.S. 

Environmental Protection Agency (USEPA) method 

1600 (1997) on-site and placed in portable incubators 

in a mobile field laboratory. Figure 6 illustrates an 

example of flow-proportional automated collection of 

samples for analysis of chemical and bacterial constituents. EMCs for analysis of fecal-indicator bacteria 

were mathematically determined by calculating the 

average value for flow-weighted concentrations of 

sub-composites.

Miscellaneous Debris 

Samples

The automatic samplers used at the inlet and 

outlet of each structural BMP limited the particle sizes 

of suspended sediment collected to less than 9.5 mm in 

diameter; this limitation excluded large organic 

cles and debris such as litter and leaves. Thus, l

buoyant and neutral buoyant (particles that neit

settle or float) particles were sampled by attach

debris-collection device (fig. 7) to the outlet hea

of station 739. Sampling the inflow for debris w

practicable during this study because the sampl

cess could adversely affect the flow to the oil-g

rator. The device consisted of a 1.5- by 1.5- by 

wood frame covered on 5 sides with a 6- by 6-m

galvanized-steel screen. The captured material w

retrieved, through an access door on the top of t

device at the end of each storm or series of storm

quantity of captured material was determined by 

the contents at 105 ̊C to a constant weight, and 

debris was identified by visual inspection of eac

sample. Identifiable materials were placed in ge

categories, such as gravel, cigarette butts, plasti

(wrappers, Styrofoam, and other plastics), and v

tive matter. The net weight of each category for 

sample was measured and recorded to the neare

milligram.

Measurement of Volume and 

Mass of Bottom Material in the 

Oil-Grit Separators and the 

Catch Basin

Bottom material is a mixture of sediment, 

organic material (leaves and sticks), roadway ma

and litter remaining on the bottom of structural 

between storms (Bent and others, 2000). For th

pose of this report, bottom sediment is bottom m

that does not contain litter or other identifiable 

als, such as metal objects. Two methods were u

measure the volume of bottom material in each 

During site assessments in November 1998 and 

active monitoring in December 1999 and Januar

measurements of depth (from the water surface 

top of the accumulated bottom material) were m

with a calibrated staff at a minimum areal densi

1 measurement per square foot. During the site 

ment of separator 739-01 in August 1999, prior 

the monitoring period, and also in June 2000 du

subsequent assessments of all three separators a

catch basin at the end of the monitoring period, 

four depth measurements were made with an en

neer’s rule per square foot after each BMP was d
18 Effectiveness of Three Best Management Practices for Highway-Runoff Quality along the Southeast Expressway, Bosto

0.0

0.1

0.2

0.3

0.4

0.5

0.6

CUBIC FEET PER SECOND

Fecal bacteria

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

COLONIES PER 100 MILLILITERS

B.

A.

Enterococci bacteria

0

2,000

4,000

6,000

8,000

10,000

12,000

10:4511:0011:1511:3011:4512:0012:1512:3012:4513:0013:1513:3013:45

TIME OF DAY

COLONIES PER 100 MILLILITERS

C.

EXPLANATION

FLOW, IN CUBIC FEET PER 

Automated flow-proportional sample collection

Bacteria composite 1

Bacteria composite 2

Bacteria composite 3

Bacteria composite 4

EVENT MEAN CONCENTRAT

SUBSAMPLES

Figure 6. Example of automated flow-proportional collection of stormwater samples at station 739, along the Southea

Expressway, Boston, Massachusetts.
Collection and Analysis of Sam

A centrifugal pump with a transparent discharge line 

was used to drain each device. The pump intake was 

fitted with a strainer that had a 1-ft2 plate mounted on 

the bottom to reduce direct vertical drafting near the 

sediment interface. The pump intake was placed just 

below the water surface in the first chamber of the separators to avoid drawing floating debris into the second 

chamber, and was lowered as the water level decreased 

until the BMP was nearly empty. The discharge hose 

was continually monitored for visual changes in turbidity as the intake lowered. The volume of bottom material was estimated by iterative averaging between 

volumetric measurement points at an areal density of 

16 points per square foot.

Bottom-material cores were collected in the 

catch basin and the first chamber of the separators with 

a 2-in.-diameter acrylic tube. A thin flexible spatula 

was used to seal the core in the tube prior to removal. 

The length of the core was recorded and the contents 

stored in a resealable bag. Cores were not collected in 

the second chamber of the separators because the core 

tube could not penetrate the large amount of decaying 

vegetation and other debris in the bottom mater

Instead, grab samples were collected at several 

tions and composited into a resealable bag. The 

of the grab samples was estimated by measurin

depth of bottom material after allowing it to set

several days in a vessel of known size. Several 

and samples were collected in each structural B

(and chamber, where possible) for particle-size 

density analysis. Particle-size analysis was perf

at the USGS Iowa Sediment Laboratory (Guy, 1

Density was determined in the USGS Massachu

District laboratory by drying known volumes of 

ment to a constant weight. The bottom-material 

each structural BMP was estimated by multiply

total volume of bottom material contained in ea

chamber by the associated density.

The contents of the bottom material were 

fied by visual inspection of each dried sample. 

able materials were placed in general categories

as glass, metal (tin foil, bottle caps, and other m

objects), cigarette butts, plastics (wrappers, Styr

and other plastics), and vegetation. The net wei

each category for each sample was measured an

recorded to the nearest milligram.

Collection of Bottom-Material 

Samples from the Oil-Grit 

Separators

Samples of bottom material were collecte

from three 1,500-gal oil-grit separators in Nove

1998 and from December 1999 through January 

with the use of a stainless steel Eckman dredge 

(Wildco). The Eckman dredge can be used to co

clay, silt, and sand-sized particles (Mudroch an

MacKnight, 1994). The dredge was deployed se

times at different locations from each manhole 

vide adequate sample volume and a representati

ple. Samples of bottom material from each cham

were removed from the dredge and placed in a 

Figure 7. Debris-collection structure at the outlet of an oilgrit separator during a rainstorm on May 25, 2000, station 

739, Southeast Expressway, Boston, Massachusetts.
20 Effectiveness of Three Best Management Practices for Highway-Runoff Quality along the Southeast Expressway, Bosto

pre-cleaned, stainless steel bowl and homogenized with 

a stainless steel spatula. Samples were collected and 

placed in pre-cleaned containers and preserved on 

ice for subsequent processing of bottom sediment 

in the USGS Massachusetts District laboratory and 

for particle-size analysis at USGS Iowa Sediment 

Laboratory. Grab samples of native water were also 

collected and placed in pre-cleaned, Teflon-lined 

bottles. The Eckman dredge, stainless steel bowl, and 

stainless steel spatula were cleaned in the field between 

sites by washing the interior and exterior with a 

phosphate-free laboratory-grade soap and tap water, 

scrubbing the surfaces with a plastic brush, and rinsing 

with deionized water. 

Samples of bottom material collected from three 

separators in November 1998 were composited in proportion to the estimated volume of retained material in 

each separator. Composites of bottom material collected from each separator from December 1999 

through January 2000 were processed individually for 

chemical analysis relative to three particle sizes, in 

part, by using the methods described by Shelton and 

Capel (1994). The contents of the bottom material were 

visually inspected and nonhomologous materials (for 

example, plastic and foil wrappers) that could bias 

chemical analysis were removed. With a Teflon 

squeeze bottle and native water, the original sample 

was wet-sieved through a pre-cleaned 2.00-mm sieve. 

A subsample of the sieved material was wet-sieved a 

second time with a pre-cleaned 0.062-mm nylon-mesh 

sieve and plastic-sieve frame. Native water and sediment particles less than 0.062 mm in diameter were 

collected in a pre-cleaned bottle and allowed to settle 

for several days. The supernatant was decanted and the 

sediment retained for chemical analysis. Particles (consisting of gravel, asphalt, leaves, and woody debris 

greater than 2.00 mm in diameter) were reduced to less 

than 2.00 mm in diameter and homogenized in a laboratory blender made of stainless steel and borosilicate 

glass to ensure a representative sample. 

Samples of bottom sediment consisting of particles less than 0.062 mm in diameter, between 

0.062 mm and 2.00 mm in diameter, and particles originally greater than 2.00 mm in diameter were submitted 

to XRAL Laboratory for analysis of 32 inorganic elements and total organic carbon (TOC). Concentrations 

of inorganic constituents were determined with the use 

of ICP emission spectroscopy and two different digestion methods for size fractions less than 0.062 mm in 

diameter and between 0.062 mm and 2.00 mm in 

diameter (site 136 did not include both digestion 

methods for particles less than 0.062 mm becau

lack of available sample volume). Two analytic

ods were used to compare the differences in dig

procedures that can affect measured trace-elem

centrations and to provide greater transferability 

other studies. The primary method, USEPA me

3050B (U.S. Environmental Protection Agency, 

digested samples with repeated additions of nitr

and hydrogen peroxide. The secondary method, 

method ICP70 (Société Générale de Surveillanc

2001), digested samples with aqua regia acid. D

tion procedures for total recoverable trace elem

such as the two methods discussed, have been p

ously considered by the USEPA as a method tha

provide an indication of the bioavailability of tr

ments (U.S. Environmental Protection Agency, 

however, concentrations of total recoverable tra

ments do not necessarily relate to ecosystem eff

and should be considered as one of many expla

variables to be measured in addition to more dir

measurements of the ecological effects on aquat

(Breault and Granato, 2000; Buckler and Grana

1999). TOC was determined by infrared spectro

Samples of bottom sediment consisting of partic

than 2.00 mm in diameter and particles original

greater than 2.00 mm in diameter were submitte

the USGS National Water Quality Laboratory in 

Lakewood, Colorado, for analysis of polyaroma

hydrocarbons (PAHs) and total polychlorinated 

nyls (PCBs) (Foreman and others, 1995). Partic

analysis excluded all identifiable debris, such as 

sticks, cigarette butts, wrappers, and other plast

items.

Sediment Samples from 

Mechanical Street Sweepers

Mechanical street sweepers were used on 

the pavement three times during the study perio

(November 1998 through June 2000). Mechani

sweepers use revolving brushes to move particu

into the path of a horizontal cylindrical brush th

pushes material onto a conveyer belt leading to 

storage hopper. The street was swept during the 

late evening hours to reduce traffic disruptions. 

MassHighway personnel collected grab sample

the center of the hopper when the street sweeper 

the vicinity of the highway test sites. Samples w

processed for particle-size analysis at USGS Io

Sediment Laboratory as described previously.
Quality Assurance / Quality Co

QUALITY ASSURANCE/ 

QUALITY CONTROL

The reliability of the real-time measurements 

and suspended sediment, chemical, and biological data 

was ensured by the preparation and analysis of many 

types of quality-control samples. These data were summarized to assess the potential for sample contamination and the accuracy and precision of various types of 

sample analysis and sampling methods. These analyses 

provided the basis for the interpretation of the efficiency of each BMP.

Quality-Control Samples

The reliability of the data collected as part of this 

study was ensured by the preparation and analysis of 

concurrent field replicates, replicate splits, sequential 

replicates, equipment blanks, field blanks, sourcesolution blanks, material blanks, and ambientatmospheric blank samples. In addition to the collection of quality-control samples, numerous other tests 

were done to ensure the reliability and representativeness of the data. Replicate samples provide a measure 

of any variability introduced during sample collection, 

processing, and analysis. In this study, concurre

replicates were samples collected at the same ti

comparable methods; split replicates were subs

from a single sample; and sequential replicates 

two or more samples collected at the same locat

at slightly different times. Replicate samples we

lyzed by comparing the relative percent differen

(RPD) of the results. Equipment blank samples 

used to test for positive bias that could have res

from contamination from any stage of the collec

analytical process. A processing blank was simi

an equipment blank, but sample water was expo

only to sample-processing equipment, not samp

equipment. Source-solution blanks were prepare

deionized water produced by a Millipore purific

system that uses reverse osmosis and electrodei

tion. Deionized water was also used to clean eq

ment. The material blank consisted of source so

in which a material fragment was soaked. Amb

atmospheric blanks consisted of source solution 

exposed to ambient and atmospheric conditions 

prevailed when the sampling equipment was cle

and when environmental samples and equipmen

blanks were processed. Quality-control samples 

summarized in table 3.

1Two equipment blanks collected for dissolved organic carbon.

Table 3. Summary of quality-control samples collected in the structural best management practices along the Southea

Expressway, in the U.S. Geological Survey, Massachusetts District laboratory, and by the U.S. Geological Survey, Off

Water Quality, Branch of Quality Systems

[--, no data]

Sample type

Number of quality-control samples collected

Suspended-sediment

concentrations

Bottom-sediment

quality Water quality Fecal-inbacte

Field blank....................................... -- -- -- 4

Equipment blank ............................ 16 -- 11 2

Replicate split.................................. 4 3 5 2

Lab duplicate................................... -- 2 -- --

Sequential replicate ......................... 27 -- -- --

Concurrent replicate ........................ 30 -- -- --

Single blind ..................................... 3 -- -- --

Double blind.................................... 6 -- -- --

Particle size ..................................... -- 3 -- --

Source-solution blank ..................... -- -- 2 1

Ambient-atmospheric blank ............ -- -- 2 --

Material blank ................................. -- -- 1 --

Data location (this report) ............... Appendix 1,

Table 1B, 1C, 1D, 1H

Appendix 1,

Table 1G

Appendix 1,

Table 1H

Appen

Table 
22 Effectiveness of Three Best Management Practices for Highway-Runoff Quality along the Southeast Expressway, Bosto

All continuous-monitoring equipment was tested 

under controlled conditions prior to installation and 

met or exceeded the manufacturer’s specifications. Site 

visits were generally conducted at a minimum frequency of once per week. During each site visit, an 

independent measurement of the water level of the oilgrit separator was compared to the current datalogger 

measurement, and debris accumulation was noted and 

removed from the inlet, outlet, and bypass pipe of each 

oil-grit separator and from the stormwater-collection 

structure installed in the deep-sumped hooded catch 

basin. Probes were inspected, cleaned, and calibrated 

as necessary, and the sample and pumping system tubes 

were inspected for wear and debris accumulation. On a 

less frequent schedule, the precipitation gage was 

inspected and tested. In general, continuous water-level 

measurements were within 0.02 ft, temperatures were 

within 0.5 ̊C, and specific conductance was within 

10 percent of check measurements. Error associated 

with turbidity sensor fouling was minor, but sensors 

exhibited a large amount of drift and became 

inoperative when temperatures were near freezing. 

The water-quality pumping system that operated semicontinuously performed satisfactorily; however, coarse 

debris and glass particles periodically deteriorated 

the pump-head tubing, which caused the pump to 

malfunction.

About 3 percent of all samples for the analysis of 

suspended-sediment concentration from the structural 

BMPs were quality-control samples. These included 

equipment blanks, field replicate and sequential replicate samples, composite split replicates, and doubleblind samples. These data are tabulated in appendix 1, 

tables 1B, 1C, and 1D. Equipment blanks were collected with the use of deionized water. Blank water was 

processed through the automatic-sample collection system, collected, and analyzed by the sediment laboratory, in a manner similar to the processing of 

environmental samples. Equipment blank samples 

were compared to the most recently collected environmental samples to determine the amount and extent of 

any cross-contamination between samples. Concurrent 

field replicates were collected by several different 

methods to assess sampling variability. Grab replicate 

samples were collected simultaneously with environmental samples collected automatically. Grab samples 

were limited to intake locations where highway runoff 

discharged from elevated pipes. Automatic replicate 

samples were collected simultaneously with a s

automatic sampler with the intake mounted on t

static mixer adjacent to the primary sampler int

Concurrent replicate automatic samples were co

over the duration of the entire storm for four ru

events. In order to determine the average partic

distribution, concurrent and sequential replicate 

ples of suspended sediment were collected with 

automatic samplers that had intake tubes vertica

distributed throughout the water column. The lo

tube was fixed to the static mixer. Samples of su

pended sediment were collected at three differe

depths simultaneously at flows of 0.13, 0.22, an

0.45 ft3/s. Composite-split replicates were prep

from the samples in the Teflon-lined 20-L bottle

the processing methods described earlier. 

In addition to other quality-control sampl

single-blind and double-blind samples were sub

to the sediment laboratory during 1999 and 200

Single-blind samples were samples of known c

trations and particle-size distribution values tha

submitted to the sediment lab for analysis and i

fied as quality-control samples. Laboratory resu

were compared to the known values to measure 

and variance of suspended-sediment data. In ad

double-blind samples were identified as environ

samples and submitted to the laboratory to meas

bias and variance of suspended-sediment data. Q

assurance procedures for the USGS Kentucky D

Sediment Laboratory are described in Sholar an

Shreve (1998).

Replicate samples for chemical analysis w

random subsamples of processed homogenized 

sediment from the separators. Quality-control s

for particle size consisted of subsamples of pro

homogenized bottom sediment in the size range 

0.062 mm to 2.00 mm in diameter from each se

These samples were mixed with deionized wate

analyzed for particle size at the 0.062-mm brea

determine the composition of the size fraction. 

nation of the 0.062-mm sieves subsequent to pr

ing indicated that there was no observable disto

the screen. 

About 20 percent of all water-quality sam

collected from the structural BMPs were replica

posite splits. In addition, one equipment blank, 

material blank, two ambient-atmospheric blank

two source-solution blanks, which were used fo
Quality Assurance / Quality Co

sample-equipment cleaning and equipment blanks, 

were collected. The material blank was collected on a 

small piece (about 54 cm2) of the polymer that was 

used to construct the static mixers and the stormwatercollection structure. Preparation of the polymer piece 

was consistent with the procedures for cleaning the 

water-quality-sampling equipment outlined earlier. 

Sample preparation for metal analysis included soaking 

the polymer piece in inorganic blank water acidified to 

a pH less than 2 with hydrochloric acid for 48 hours. 

Sample preparation for PCB and PAH analysis 

included soaking the polymer piece in organic blank 

water for a period of 48 hours. 

Replicate split samples for analysis of fecalindicator bacteria were collected from composites of 

two or more discrete samples. Processing blanks were 

collected for analysis of fecal and Enterococci bacteria 

during each sampled storm. Equipment blanks and 

source-solution blanks also were analyzed.

Quality-Control Data

Quality-control data were summarized to assess 

the potential for contamination, and to assess the accuracy and precision of the data. The quality-control data 

indicated that continuous records of water level, flow, 

and precipitation were within the measurement uncertainties of the individual sensors. About 90 percent of 

the estimated precipitation, determined on the basis of 

the drainage area of each monitoring site, was 

accounted for in stormwater flows at each site. These 

relations of total flows to total precipitation for each 

storm compared favorably with runoff coefficients 

developed in other highway studies (Driscoll and 

others, 1990). The mean RPD between the concentration of suspended sediment in samples collected by the 

automatic sampler and in replicate grab samples collected concurrently was 4 percent over a range of flows 

from about 0.03 to 0.41 ft3/s. The mean RPD between 

the concentrations of suspended sediment in pairs of 

replicate suspended-sediment samples collected concurrently by automatic samplers was about 8 percent 

over a range of flows from about 0.01 to 0.10 ft3/s. The 

aforementioned flow ranges span the average storm 

flows for the monitoring period at each BMP. The average cross-contamination among equipment blanks for 

samples of suspended sediment for the six sites is estimated to be about 5 percent. Replicate samples for the 

analysis of suspended-sediment concentration c

lected automatically across the water column w

the inlet of a separator, collected concurrently 

and sequentially, indicated that particles less th

0.062 mm in diameter were evenly distributed t

out the water column. Concentrations of particl

greater than 0.062 mm in diameter, however, ten

higher near the bottom of the pipe despite the tu

lence created by the static mixers. Flow-weight

vertical concentration trends relative to three flo

are illustrated in figure 8. This concentration di

tion compared favorably with patterns in data fr

ural fluvial systems (Guy, 1970) and described i

highway systems (Bent and others, 2000). Figu

illustrates the range of runoff flows at stations w

samples for the analysis of suspended-sediment 

centration were collected through the study peri

maximum rate of flow and the median of averag

of flows for the monitoring periods for the sepa

were 2.85 and 0.06 ft3/s, respectively, at station 

and 1.72 and 0.05 ft3/s, respectively, at station 1

maximum rate of flow and the median of averag

of flows for the monitoring period for the catch 

were 1.37 and 0.01 ft3/s, respectively. The diffe

between the median and interquartile ranges of 

arators were the result of how long and when ea

tion was monitored. Station 136 was operated f

months longer than station 739, and the monito

period included the entire spring and early sum

1999. During the summer, storms were short an

intense; thus, the flows were typically greater th

storms later in the study.

The results of the USGS Kentucky Distri

Sediment Laboratory participation in the USGS 

of Quality Systems (BQS) single-blind referenc

project indicated that sample bias for concentra

suspended sediment-size fractions less than 0.0

and greater than 0.062 mm in diameter during th

period was minimal, typically less than 5 perce

(Shreve, E.A., U.S. Geological Survey, written 

commun., 2001). The median difference betwee

centrations of double-blind suspended sedimen

ples and known sample concentrations was less 

percent (appendix 1, table 1C). 

Quality-control data indicated that the res

of the analyses of most bottom-sediment sampl

inorganic elements and organic compounds wer

rate and reproducible (figs. 10 and 11, appendix 
24 Effectiveness of Three Best Management Practices for Highway-Runoff Quality along the Southeast Expressway, Bosto

0.08

0.10

0.12

0.14

0.16

0.18

0.20

0.22

0.24

RATIO OF FLOW-WEIGHTED SUSPENDED SEDIMENT CONCENTRATIONS AT VARIOUS SAMPLE LOCATIONS TO TH

FLOW-WEIGHTED SUSPENDED SEDIMENT CONCENTRATIONS AT THE PRIMARY SAMPLING LOCATION (0.08 fee

DISTANCE ABOVE PIPE FLOOR, IN FEET

0.4 0.5 0.6 0.7 0.8 0.9 

Suspended sediment ratio at flow of 0.13 cubic feet per second

Suspended sediment ratio at flow of 0.22 cubic feet per second

Suspended sediment ratio at flow of 0.45 cubic feet per second

table 1G). Field and laboratory replicate samples were 

analyzed by comparing the RPDs of the results. The 

RPD was typically less than 25 percent for most pairs 

of samples; an RPD of less than 50 percent between 

measurements from replicate bottom-sediment samples 

is considered to be acceptable (Breault and others, 

2000). RPDs exceeded 50 percent for only two replicate samples for TOC, two samples for barium (Ba), 

one sample for cadmium (Cd), and one sample for lead 

(Pb). The large RPD for the Cd sample was a result of 

one concentration near the detection limit and the other 

concentration below the detection limit. Particles less 

than 0.062 mm in diameter (about 0.5 percent) were 

virtually absent in samples of bottom sediment in the 

size range of 0.062 to 2.00 mm indicating that the 

particle-size composition of these samples was relatively pure. This is important because particles less 

than 0.062 mm in diameter contained higher concentrations of selected constituents compared to other size 

ranges; thus, the presence of even small quantities (as 

low as 5 percent) of particles less than 0.062 mm in 

diameter could have increased the concentration

selected constituents in the size range of 0.062 

2.00 mm in diameter.

Quality-control data indicated that most o

results of analysis for water samples were accur

reproducible (appendix 1, table 1H). The media

between replicate composite splits for dissolved 

ions, dissolved organic carbon (DOC), oil and g

(O&G), and nutrients—except for total phospho

orthophosphorus (PO4), and total organic ammo

(NH3), were less than 4 percent. The median RP

between replicate composite splits for total P, P

total organic NH3 were about 16, 9, and 9 perce

respectively. The median RPDs between replica

for suspended organic carbon (SOC) and total p

leum hydrocarbons (TPH) were 25 and 12 perc

respectively. The median RPDs between replica

for chemical oxygen demand (COD), total PAH

total PCBs were all less than about 8 percent. T

median RPDs between replicate splits for total 

chromium (Cr), copper (Cu), iron (Fe), mangan

(Mn), Pb, and zinc (Zn) were all less than 5 per

Figure 8. General trend for flow-weighted suspended-sediment concentrations relative to the sample location in t

water column of a 12-inch pipe at the inlet of the oil-grit separator at station 136, along the Southeast Expresswa

Boston, Massachusetts.
Quality Assurance / Quality Co

(358) (457) (378) (378) (312) (243)

739-02 (OUTLET)

739-03 (INLET)

136-02 (OUTLET)

136-03 (INLET)

136-04 (OUTLET)

136-05 (INLET)

STATION

0.001

10

0.002

0.003

0.004

0.005

0.007

0.01

0.02

0.03

0.04

0.05

0.07

0.1

0.2

0.3

0.4

0.5

0.7

1

2

3

4

5

7

RUNOFF FLOWS AT TIME OF SAMPLE COLLECTION, IN CUBIC FEET PER SECOND

EXPLANATION

25th percentile

Median

75th percentile

the interquartile range outside the 

Data value less than or equal to 1.5 

interquartile range outside the qua

and more than 1.5 times the

Outlier data value less than or equa

interquartile range outside the qua

Outlier data value more than 3 time

(358) Number of observations

Figure 9. Distribution of runoff flows at time of sample collection for the inlet and outlet of each structural best manag

practice, along the Southeast Expressway, Boston, Massachusetts.
ctiveness of Three Best Management Practices for Highway-Runoff Quality along the Southeast Expressway, Boston, MA

0

1

2

3

4

5

6

7

8

PARTS PER MILLIO

0

2

4

6

8

10

12

14

16

18

20

PARTS PER MILLION

0

2

4

6

8

10

12

14

16

18

20

PARTS PER MILLION

Antimony Arsenic Cobalt Molybdenum

Yttrium

LD D LD D D

136-01 739-01 749-01

LD D LD D D

136-01 739-01 749-01

LD D LD D D

136-01 739-01 749-01

ANALYSIS BY XRAL ICP70 METHOD

ANALYSIS BY EPA 3050 METHOD

Less than 0.062 millimeters

0.062 to 2.0 millimeters

Greater than 2.0 millimeters

LAB DUPLICATE

FIELD DUPLICATE 

EXPLANATION

LD

D

LD D LD D D

136-01 739-01 749-01

Zirconium

Figure 10. Distribution of inorganic elements by particle size in sediment samples collected from oil-grit separators located along the Southeast Expressway, Boston, 

Massachusetts.
Quality Assurance / Quality Control 27

0

10

20

30

40

50

60

70

PARTS PER MILL

Barium Chromium

0

80

160

240

320

400

480

560

640

720

800

PARTS PER MILLION

0

80

160

240

320

400

480

560

640

720

800

PARTS PER MILLION

Manganese

LD D LD D D

136-01 739-01 749-01

LD D LD D D

136-01 739-01 749-01

LD D LD D D

136-01 739-01 749-01 LD D LD D D

136-01 739-01 749-01

Copper Lead

Tin

EXPLANATION

LD

D

ANALYSIS BY XRAL ICP70 METHOD

ANALYSIS BY EPA 3050 METHOD

Less than 0.062 millimeters

0.062 to 2.0 millimeter

Greater than 2.0 millimeters

LAB DUPLICATE

FIELD DUPLICATE 

Figure 10. Distribution of inorganic elements by particle size in sediment samples collected from oil-grit separators located along the Southeast Expressway, Boston, 

Massachusetts—Continued.
ctiveness of Three Best Management Practices for Highway-Runoff Quality along the Southeast Expressway, Boston, MA

Magnesium Sodium Aluminum

Iron

0

500

1,000

1,500

2,000

2,500

3,000

3,500

PARTS PER MIL

Calcium

0

6,000

12,000

18,000

24,000

30,000

36,000

42,000

48,000

54,000

60,000

PARTS PER MILLION

0

6,000

12,000

18,000

24,000

30,000

36,000

42,000

48,000

54,000

60,000

PARTS PER MILLION

LD D LD D D

136-01 739-01 749-01

LD D LD D D

136-01 739-01 749-01

LD D LD D D

136-01 739-01 749-01

LD D LD D D

136-01 739-01 749-01

EXPLANATION

LD

D

ANALYSIS BY XRAL ICP70 METHOD

ANALYSIS BY EPA 3050 METHOD

Less than 0.062 millimeters

0.062 to 2.0 millimeters

Greater than 2.0 millimeters

LAB DUPLICATE

FIELD DUPLICATE 

Figure 10. Distribution of inorganic elements by particle size in sediment samples collected from oil-grit separators located along the Southeast Expressway, Boston, 

Massachusetts—Continued.
Analysis of 

The median RPDs between replicate splits for total 

arsenic (As) and nickel (Ni) were 14 and 8 percent, 

respectively. In general, the largest RPDs were found in 

samples that contained high concentrations of c

particles (in excess of 0.250 mm). The median R

concentrations of suspended sediment in replica

splits was about 13 percent. The RPD between s

with a majority of particles less than 0.062 mm 

diameter, however, was about 4 percent. Particle

in composite samples were as large as 4 by 7 m

weighed as much as 180 mg; thus, the low prec

the analysis of suspended-sediment samples con

coarse material was likely caused by one sampl

only a few additional particles. 

Source-solution blanks prepared from de

water for the analyses of water and bacteria wer

from contaminants with respect to the minimum 

ing limit (MRL) used for sample analyses, with 

exception of trace amounts of silica, and a singl

tion of ammonia (NH4-N) and benzo-[GHI] per

Ambient-atmospheric blanks prepared from sou

water were free from contaminants. The materia

was free from contaminants, with the exception 

amounts of Ni and aluminum (Al). The equipm

blank contained trace amounts of NH4-N and DO

analysis of this blank indicated no substantial c

nation from the wetted parts of the equipment, t

cleaning procedure, or any stage of the sample 

tion. A subsequent analysis of the equipment bl

indicated that DOC was below the MRL.

Equipment and source-solution blanks an

for bacteria indicated that the cleaning and steri

process was satisfactory. A single processing bl

suggested that contamination occurred once in 

field. The contamination, which may have been 

result of an airborne particle in the mobile labo

occurred prior to any sample collection and was 

orders of magnitude below sample concentratio

RPDs between all pairs of replicate split sample

fecal-indicator bacteria were less than 21 perce

ANALYSIS OF DATA

Concentrations of suspended sediment w

combined with continuous records of flow and 

control data to estimate suspended-sediment loa

each monitoring location. A mass-balance calcu

was used to assess the effectiveness of each stru

BMP in reducing suspended-sediment loads. An 

suspended-sediment load was estimated for the 

highway surface for the study area, on the basis 

the long-term average annual precipitation and 

suspended-sediment loads estimated during this 

10,000

100,000

1,000,000

PARTS PER MILLION

0.01

0.1

1

10

PARTS PER MILLION

1

10

100

1,000

LD D D D LDD D D D D

PARTS PER MILLION

136-01 739-01 749-01

EXPLANATION

LD

D

Less than 0.062 millimeters

0.062 to 2.0 millimeters

Greater than 2.0 millimeters

Less than 2.0 millimeters (no subdivision)

LAB DUPLICATE

FIELD DUPLICATE

0

Organic carbon, total (as C)

Total polychlorinated biphenyls

Total polyaromatic hydrocarbons

PARTICLE SIZE

Figure 11. Distribution of organic constituents by particle size 

in sediment samples collected from oil-grit separators located 

along the Southeast Expressway, Boston, Massachusetts.
30 Effectiveness of Three Best Management Practices for Highway-Runoff Quality along the Southeast Expressway, Bosto

Suspended-Sediment Loads

Suspended-sediment loads for the inlet, outlet, 

and bypass (oil-grit separator only) of each structural 

BMP were estimated by multiplying the concentration 

of suspended sediment in discrete samples by the discharge represented by the samples. The discharge 

applied to a particular sample (the “sample discharge”) 

was computed as the sum of half the flow that occurred 

since the collection of the preceding sample and half 

the flow that occurred before the collection of the subsequent sample. In the case of the first sample, the 

sample discharge was computed as the sum of the 

entire flow that preceded the collection of the sample 

and half the flow that occurred before the collection of 

the subsequent sample. In the case of the last sample, 

the sample discharge was computed as the sum of half 

the flow that occurred since the collection of the preceding sample and the entire volume of flow that 

occurred after the collection of the sample. In most 

cases, samples were collected in proportion to flow, so 

that in effect all sample discharges were equivalent. 

Storm loads were estimated from the summed sequential sample loads. During four storms, the automatic 

samplers were configured to collect composite samples; storm loads were estimated by multiplying the 

EMC of suspended sediment by the total storm 

discharge. 

Bypass loads were estimated on the basis of the 

concentration of suspended sediment in the inflow 

samples because no bypass samples were collected. In 

other words, the suspended-sediment concentration in 

the separator bypass and inlet pipe was assumed to be 

the same. This assumption may not necessarily be correct because quality-control data indicated that particles greater than 0.062 mm were not evenly distributed 

vertically at comparable flows. Conversely, bypass flow 

was believed to have been thoroughly mixed because 

the inflow impacted the diversion weir at a 90-degree 

angle. In fact, small gravel (greater than 6 mm in diameter) was found in the debris-collection structure at station 739 after bypass flow occurred, which indicates a 

high degree of mixing. 

An adjustment factor was applied to inlet loads 

of suspended-sediment because quality-control data 

indicated that suspended-sediment concentrations were 

not evenly distributed throughout the water column. 

Inlet loads would have been overestimated without this 

adjustment, because the sampler intake was at the 

bottom of the water column. No adjustment was necessary for the separator outlet loads because samp

suspended sediment from the outlet had few pa

greater than 0.062 mm in diameter (fig. 12). No 

ment was made in the suspended-sediment load

inlet or outlet of the catch basin because stormw

flows and the resultant water-column depths we

stantially smaller than those for the separator. A 

sion equation was developed to normalize the m

suspended-sediment concentration to the prima

sample location for samples from the separator 

This equation was based on the analysis of expe

tal samples of suspended sediment categorized 

particle-size break at 0.062 mm and collected a

characteristic of observed field conditions. The 

sediment particles greater than 0.062 mm in dia

in experimental samples ranged from 63 to 96 p

of the mass of the total suspended sediment. Th

cle-size distribution was similar to observed par

size distributions at the separator inlets at each 

(fig. 12). The following adjustment equation wa

to normalize the mean concentration of suspend

iment to the primary sample location for sampl

the oil-grit separator inlets: 

CA=C×10^ (-0.265 Log10(Q) -0.369),

where 

CA is the adjusted SSC, 

C is the initial suspended-sediment concen

and 

Q is the instantaneous discharge in cubic f

second.

No adjustment was made to the concentra

suspended sediment for samples collected at dis

less than 0.09 ft3/s because the position of the s

intake was centered approximately in the water 

and the suspended sediment was generally dom

by particles less than 0.062 mm in diameter. Th

tion provided a correction to the experimental d

within 24 percent of the flow-weighted suspend

sediment concentration. The accuracy of the adj

ment was dependent on the size and concentrati

particles present; these quantities varied with st

intensity, duration, antecedent conditions, and s

Although adjustment of only that size fraction g

than 0.062 mm in diameter was ideal, particle-s

information was not available for every storm. T

average difference, however, between the adjus

for nine storms for which particle-size informat
Analysis of 

(31) (39) (86) (90) (27) (17)

739-02 (OUTLET)

739-03 (INLET)

136-02 (OUTLET)

136-03 (INLET)

136-04 (OUTLET)

136-05 (INLET)

STATION

0.01

100

0.02

0.03

0.04

0.05

0.07

0.1

0.2

0.3

0.4

0.5

0.7

1

2

3

4

5

7

10

20

30

40

50

70

FRACTION OF SUSPENDED SEDIMENT CONCENTRATIONS GREATER THAN 

0.062 MILLIMETERS, IN PERCENT

EXPLANATION

25th percentile

Median

75th percentile

the interquartile range outside the 

Data value less than or equal to 1

interquartile range outside the qu

and more than 1.5 times the

Outlier data value less than or equ

(31) Number of observations

available and for which total suspended-sediment loads 

and suspended-sediment loads greater than 0.062 mm 

in diameter were adjusted separately, was 16 percent. 

The small difference between the adjustment techniques suggested that the greatest correction wa

essary during peak flows, which was generally 

the largest suspended-sediment loads occurred 

coarse materials were mobilized.

Figure 12. Particle-size distribution for samples of suspended sediment collected from the inlet and outlet of a deep-su

hooded catch basin and two oil-grit separators located along the Southeast Expressway, Boston, Massachusetts.
32 Effectiveness of Three Best Management Practices for Highway-Runoff Quality along the Southeast Expressway, Bosto

During the monitoring period of this study, 74 

storms produced measurable runoff at station 136, and 

59 storms produced measurable runoff at station 739. 

Samples for analysis of suspended sediment were not 

collected for 17 percent of the storms for the separator 

at station 739, for 28 percent of the storms for the separator at station 136, and for 43 percent of the storms at 

the catch basin at station 136. No bypass flows 

occurred during any of the unsampled storms. Typically, samples were not collected because of equipment 

malfunctions. Water levels in the outlet pipe and in the 

collection structure of the catch basin were lower than 

the sampler intakes during low-intensity storms, so 

more storms were not sampled for the catch basins than 

for the separators. Runoff events were sampled at a 

higher frequency for the oil-grit separators because 

they received the combined flows from several catch 

basins. To complete a mass-balance analysis, suspended-sediment loads were estimated for unsampled 

storms by multiplying the median EMC for suspended 

sediment at the inlet and outlet of each respective 

structural BMP by the total recorded flow. 

Efficiencies of Structural BMPs

A mass-balance approach was used to assess the 

effectiveness of each structural BMP in reducing suspended-sediment loads. For each sampled storm, the 

efficiency of each device was estimated by subtracting 

the outlet load from the inlet load and dividing that difference by the inlet load ((IN-OUT)/IN). Similarly, the 

efficiency of each device for the entire monitoring 

period was estimated by subtracting the sum of all of 

the outlet loads from the sum of all of the inlet loads 

and dividing that difference by the sum of all of the 

inlet loads ((∑IN-∑OUT)/∑IN). In this case, the load 

sums included loads estimated from unsampled storms. 

The overall difference between the inlet and outlet 

loads was compared to the estimate of bottom m

retained at the conclusion of the monitoring per

each structural BMP (∑IN-∑OUT=∑RETAINE

Annual Suspended-Sediment 

Loads

An annual suspended-sediment load was 

mated for the study area by multiplying the ann

highway discharge by normalized suspended-se

loads measured during this study. The annual h

discharge was estimated by multiplying the esti

pavement runoff—relative to the long-term ave

annual precipitation measured by the National O

and Atmospheric Administration (NOAA) in Bo

Massachusetts—by the total highway area. The 

the monthly precipitation values at station 136 w

about 2 in. less than the sum of the average mon

precipitation values measured by NOAA for 127 

The inlet and outlet suspended-sediment loads e

mated for similar time periods for the separator

tions 136 and 739 were respectively summed an

normalized to the sum of the respective contribu

areas. The pavement area of the two separator d

basins represented about 9 percent of the total s

area. Normalized inlet loads represented catch-

discharge and normalized outlet loads represent

arator discharges. The average effectiveness of 

structural BMP and load was assumed to be sim

throughout the study area. An annual mass of se

retained by the five separators was estimated by 

malizing the retained mass of bottom material f

separators at stations 136, 739, and 749 to the 

respective periods of operation during the study
Analysis of 

Predictors for Unsampled 

Suspended-Sediment Loads

Continuous measurements of turbidity were 

examined as a possible predictor for suspendedsediment concentrations. Turbidity is a measure of the 

light scatter caused by interference from suspended 

materials (such as silt, clay, and fine organic particles) 

and dissolved materials that produce color. Turbidity 

has been used in other studies to estimate suspendedsediment concentrations in fluvial systems (Brown and 

Ritter, 1971; Brown, 1973; Reed, 1978; Beschta, 1980; 

Smith, 1986; Gippel, 1995; and Lewis, 1996) and in 

many urban- and highway-runoff studies, including 

Irwin and Losey (1978), Cramer and Hopkins (1981), 

McKenzie and Irwin (1983); Dupuis and others (1985), 

Schiffer (1989); Spangberg and Niemczynowicz 

(1992); and Barrett and others (1996). Laboratory 

analysis of turbidity and suspended-sediment 

concentrations for 1,135 runoff samples collected from 

the inlet of each oil-grit separator and the outlet of the 

deep-sumped hooded catch basin indicates that the 

relation between measured values was qualitative (that 

is, it represents a range of values rather than an exact 

number) over the full range of measured sediment 

concentrations. For example, at a measured turbidity 

of 100 nephelometric turbidity units (NTU), the 

suspended-sediment concentrations ranged from about 

70 to 2,000 mg/L and at a turbidity of 1,000 NTU, the 

suspended-sediment concentrations ranged from about 

700 to 3,000 mg/L (fig. 13). The variability in the measurements was caused by larger particles that disproportionally influenced the turbidity in the small field of 

view of the instrument. Thus, the variability in turbidity 

measurements relative to suspended-sediment 

concentrations became smaller for samples with fewer 

particles greater than 0.062 mm in diameter. Therefore, 

the measurement of turbidity is an unreliable surrogate 

for suspended-sediment concentrations when th

sample contains particles greater than 0.062 mm 

diameter, such as in highway runoff.

The relation of the EMCs for suspended 

ment and load estimated from samples at each s

tural BMP inlet and outlet to measured storm 

precipitation and duration were investigated as 

tial predictors for unsampled storm loads. Othe

tial predictors were 5-minute and 60-minute 

precipitation intensities, antecedent dry period, 

duration, and average, peak, and total storm flow

Simple and multiple regression models with EM

suspended sediment and suspended-sediment lo

from individual storms, however, indicated that 

measured predictor could explain the variability 

EMCs for suspended sediment; the significant re

that were found between some of the potential p

tors and the suspended-sediment loads resulted 

the relations with rainfall or runoff characteristi

quantified flow per storm and the flow componen

discharge) of the suspended-sediment loads val

Therefore, because the EMCs for suspended se

were characterized as log-normal, the median E

value for suspended sediment for the monitoring 

for each structural BMP was used with the mea

flows to estimate unsampled storms. Consequen

percentage of the suspended-sediment load esti

for the inlet and outlet of each structural BMP d

the entire monitoring period was: about 11 perc

18 percent, respectively, at the separator at stati

and 17 percent and 20 percent, respectively, at t

rator at station 136; and 23 percent and 17 perc

the catch basin at station 136. Suspended-sedim

loads (including estimated loads) at the inlets a

lets of the BMPs, relative to storm precipitation 

sured at station 136, are shown for each structur

in figure 14.
34 Effectiveness of Three Best Management Practices for Highway-Runoff Quality along the Southeast Expressway, Bosto

10 100 1,000 10,000

TURBIDITY, IN NEPHELOMETRIC TURBIDITY UNITS

10

10,000

20

30

40

50

70

100

200

300

400

500

700

1,000

2,000

3,000

4,000

5,000

7,000

SUSPENDED SEDIMENT CONCENTRATIONS, IN MILLIGRAMS PER LITER

Figure 13. Relation of suspended-sediment concentrations to laboratory measurements of 

turbidity in samples collected from the outlet of a deep-sumped hooded catch basin and the inlet 

of two oil-grit separators located along the Southeast Expressway, Boston, Massachusetts.
Analysis of Data 35

0

2

4

6

8

PRECIPITATION, IN INCHES

OE

OE

OE

OE

OE

BE

OE

BE

BE

BE

BE

OE

BE BE BE

BE

4/16/19994/23/1999

5/3/19995/5/19995/8/1999

5/19/19995/23/19995/24/1999

7/1/19997/4/19997/6/1999

7/13/19997/19/19997/23/19997/24/19997/25/1999

8/6/1999

8/21/19998/26/1999

9/6/19999/7/19999/8/1999

9/10/19999/15/19999/22/19999/30/199910/4/199910/9/1999

10/10/199910/13/199910/17/199910/20/199910/23/1999

11/3/1999

11/10/199911/12/199911/14/199911/20/199911/27/1999

12/6/1999

12/15/199912/20/1999

1/4/2000

1/10/20001/13/20001/16/20001/20/20001/25/20001/31/20002/14/20002/18/20002/25/20002/26/20002/28/20003/12/20003/16/20003/28/2000

4/4/20004/8/2000

4/11/20004/16/20004/18/20004/21/20004/26/2000

5/2/20005/8/2000

5/10/20005/13/20005/18/20005/22/20005/24/20005/25/2000

6/2/20006/6/2000

6/11/20006/14/2000

DATE, STORM EVENT

0

160

20

40

60

80

100

120

140

SUSPENDED SEDIMENT LOADS, IN KILOGRAMS

INLET LOAD ESTIMATED

OUTLET LOAD ESTIMATED

BOTH INLET AND OUTLET

 LOAD ESTIMATED

B.

OIL-GRIT SEPARATOR 739-01

Street sweeping

Street sweeping

Catch basin cleaning

EVENT PRECIPITATION

INLET LOAD

OUTLET LOAD

IE

OE

BE

Figure 14. Total precipitation measured at station 136 for each runoff event and suspended-sediment loads for the inlet and the outlet of a deep-sumped hooded 

catch basin and the inlet and outlet of two oil-grit separators located along the Southeast Expressway, Boston, Massachusetts.
ctiveness of Three Best Management Practices for Highway-Runoff Quality along the Southeast Expressway, Boston, MA

BE OE

BE

BE

BE

BE

BE

BE

BE

BE

BE

BE

BE

BE

OE

OE BE

BE

BE

BE BE

OE BE

BE

BE

BE IE 

 IE IE 

0

20

40

60

80

100

120

SUSPENDED SEDIMENT LOADS, IN KILOGRA

INLET LOAD

OUTLET LOAD

BE

BEBE BEBE IE BE BE IE IE BE BE

BE

BE

BE

BE

BE BE BEBE

BE

BE

BE BE BE BE

BE

EB

BE

BE

BE BE BE

BE

4/16/19994/23/1999

5/3/19995/5/19995/8/1999

5/19/19995/23/19995/24/1999

7/1/19997/4/19997/6/1999

7/13/19997/19/19997/23/19997/24/19997/25/1999

8/6/1999

8/21/19998/26/1999

9/6/19999/7/19999/8/1999

9/10/19999/15/19999/22/19999/30/199910/4/199910/9/1999

10/10/199910/13/199910/17/199910/20/199910/23/1999

11/3/1999

11/10/199911/12/199911/14/199911/20/199911/27/1999

12/6/1999

12/15/199912/20/1999

1/4/2000

1/10/20001/13/20001/16/20001/20/20001/25/20001/31/20002/14/20002/18/20002/25/20002/26/20002/28/20003/12/20003/16/20003/28/2000

4/4/20004/8/2000

4/11/20004/16/20004/18/20004/21/20004/26/2000

5/2/20005/8/2000

5/10/20005/13/20005/18/20005/22/20005/24/20005/25/2000

6/2/20006/6/2000

6/11/20006/14/2000

DATE, STORM EVENT

0

140

20

40

60

80

100

120

SUSPENDED SEDIMENT LOADS, IN KILOGRAMS

INLET LOAD ESTIMATED

OUTLET LOAD ESTIMATED

BOTH INLET AND OUTLET LOAD ESTIMATED

D.

CATCH BASIN 136-06

IE

OE

BE

Figure 14. Total precipitation measured at station 136 for each runoff event and suspended-sediment loads for the inlet and the outlet of a deep-sumped hooded 

catch basin and the inlet and outlet of two oil-grit separators located along the Southeast Expressway, Boston, Massachusetts—Continued.
Assessment of Best Management Prac

EXPLANATION

NOVEMBER 1998

AUGUST 1999

DECEMBER 1999

JANUARY 2000

JUNE 2000

DEVICE VOLUME

 BELOW BAFFL

 OPENINGS 

0

5

10

15

20

25

30

35

40

45

50

55

60

65

SEPARATOR 136-01 SEPARATOR 739-01 SEPARATOR 749-01

VOLUME, IN CUBIC FEET

ASSESSMENT OF BEST 

MANAGEMENT PRACTICES

The principal purpose of most highway BMPS is 

to reduce the amount of sediment and sediment-associated constituents discharged from the roadway surfaces. The advertised effectiveness of many BMPs, in 

many cases, was determined theoretically, or the effectiveness was estimated on the basis of a few artificial 

storms where flow rate and particle size was controlled. 

In this study, structural BMPs were tested under real 

highway operating conditions for as long as 18 months. 

Automatic-monitoring and -sampling techniques were 

used to characterize the temporal and spatial variability 

in suspended-sediment loads and selected chemical 

concentrations transported through each structural 

BMP. A mass-balance calculation was used to quantify 

the accuracy of the estimated sediment removalefficiency for each structural BMP. Thorough estimates 

of BMP efficiencies, such as these, are necessary to 

guide, substantiate, and defend highway BMP selection 

and planning decisions. 

Temporal Variability of 

Retained Bottom Material

The volume of bottom material in the separators 

was estimated three times at stations 136 and 749, four 

times at station 739, and once in the catch basin at the 

conclusion of the monitoring period. Additional assessments of the bottom material in the catch basin were 

not practicable because the device was located beneath 

the travel lane of the highway. The volume of re

bottom material estimated during the initial asse

of each separator in November 1998 represente

ment accumulation from about three years of op

tion. Subsequent assessments were done in Dec

1999, January 2000, and in June 2000, when da

lection was completed. Prior to cleaning the sep

at station 739, one additional assessment was m

August 1999.

The physical distributions of bottom mate

the separators were similar. In general, coarse m

was deposited near the inlet of the primary cham

(fig. 2). A lateral deposit of less coarse material 

extended to each of the three baffle openings, w

greatest amount of material deposited near the b

the primary chamber. The corner opposite to th

and to the baffle of the primary chamber was ge

free of deposition. The depth of bottom materia

second chamber of each separator was greatest n

baffle outlets and decreased near the chamber ou

the volume of material in the second chamber 

increased over time, the distribution of the botto

material became more uniform. The estimated t

volume of retained bottom material in the separ

the conclusion of the study, in contrast to the es

volume of retained bottom material in the separ

after three-years of operation without any maint

was about 25 percent less at station 136 after a 

month period, about 46 percent less at station 7

a 10-month period, and about 108 percent great

station 749 after a 18-month period (fig. 15). Th

depth of the bottom material in each chamber o

separators at stations 136 and 739 was not more 

Figure 15. Temporal variability of the volume of bottom material in three oil-grit separators located along the 

Southeast Expressway, Boston, Massachusetts.
38 Effectiveness of Three Best Management Practices for Highway-Runoff Quality along the Southeast Expressway, Bosto

0

5

10

15

20

25

30

35

40

45

<0.062 0.125<0.062 0.25<0.125 0.5<0.25 1<0.5 2<1 4<2 8<4 16<

RANGE, IN MILLIMETERS

SIZE DISTRIBUTION, IN PERCENT

DEEP-SUMPED HOODED CATCH BASIN

OIL-GRIT SEPARATOR PRIMARY CHAMBER

OIL-GRIT SEPARATOR SECONDARY CHAMB

about 5 in.; the surface of the bottom material was 

located at about 72 percent of the distance to the 

bottom of the baffle outlets. The depth of the bottom 

material in each chamber of the separator at station 

749, however, was about 14 in.; the surface of the 

bottom material was located at about 22 percent of the 

distance to the bottom of the baffle outlets. The difference between the volume of bottom material measured 

in each separator after three years of operation without 

any maintenance and at the end of the study periods 

indicate that the estimated rate of bottom-material 

accumulation was about two times greater during the 

study period at stations 136 and 739, and about seven 

times greater at station 749. The increase in the estimated rate of bottom-material accumulation is uncertain because the density of the bottom material for the 

first three years of operation was unknown and suspended-sediment data was not available prior to this 

study. One possible explanation for the increase in 

the rate of bottom-material accumulation during the 

study, or perhaps more specifically, the lack of accumulation during the first three years of operation, is that a 

single (or multiple) storm(s) resuspended a portion of 

the bottom material retained in the separators during 

the first three years of operation and flushed the suspended materials from the device. Thus, the rate of 

accumulation would have been distorted by the loss of 

retained bottom material. The lack of bottom-material 

accumulations in separators due to resuspension was 

noted by Schueler and Shepp (1993), who monitored 

17 separators on a monthly basis. They found th

ment depths changed frequently, but that the ma

accumulated bottom material did not increase f

year to year. In this study, the small increase of r

materials in the second chamber of the separato

tion 749 between January 2000 and June 2000 i

cated that small particles were easily resuspend

the level of sediment approached the bottom of 

baffle openings. 

Particle-Size Distribution and 

Contents of Retained Bottom 

Material

Samples of bottom material collected fro

structural BMP and analyzed for particle size w

data monitoring was completed represented a te

composite of sediment and debris deposition fo

structural BMP. Particle-size data for samples o

bottom material are listed in appendix 1, table 1

sediment in the catch basin (about 83 percent) a

in the primary chamber of the three separators (

weighted average of 85 percent) was coarse-gra

(greater than 0.25 mm in diameter), whereas a g

amount of sediment in the secondary chamber o

three separators was fine-grained (a weighted av

of about 50 percent was less than 0.25 mm in di

(fig. 16). The percentage of particles found in ea

class, for classes less than 0.062 mm in diamete

greater than 0.5 mm in diameter, was substantia

Figure 16. Particle-size distribution of a sample of bottom sediment collected from a deep-sumped hooded catch b

and the weighted-average particle-size distribution of samples of bottom sediment collected from three oil-grit sepa

located along the Southeast Expressway, Boston, Massachusetts.
Assessment of Best Management Prac

different for the two chambers of the separators. Otherwise, the percentage of bottom material particles in 

each size class was similar, with respect to sample 

location, for each separator.

About 17 percent of the material in each separator and about 7 percent of the material in the catch 

basin was less than 0.062 mm in diameter. These percentages were larger than expected because the retention times of the structural BMPs were short. For 

example, the estimated time to exchange one complete 

volume of water in the catch basin, based on the 

median of the maximum storm flows, was approximately 7 minutes; the exchange rate for the separators 

was about 11 minutes. Maximum instantaneous flows 

measured during the monitoring period for the catch 

basin and the separator would have exchanged the 

volume of water in a minute or less for each device. It 

was unlikely that particles less than 0.062 mm in diameter were deposited during flow through the BMPs, 

because it can take a time interval from an hour to several days for particles in this size class to settle, even 

under static conditions. Thus, the occurrence of 

bottom-material particles in this size range was likely 

a result of static settling subsequent to each storm. 

Furthermore, the proportion of particles less than 

0.062 mm in diameter was larger in the second chamber; this result indicates that particles in this size range 

in the first chamber were more often resuspended 

during runoff events.

Each chamber of the three separators was periodically inspected throughout the monitoring period for 

floating debris. Within 6 months of the separator 

cleaning, about 70 percent of the surface area o

primary chamber was covered with nondescript 

ing debris. The secondary chamber of each sepa

very rarely contained floating debris. Despite th

appearance of the surface of the primary chamb

ples of bottom material collected in the seconda

chamber contained nearly an order of magnitud

debris than samples collected in the primary ch

Over time, some floatable debris could become 

trally buoyant and pass through the baffle durin

Such materials were commonly retained in the 

chamber below the baffle, where they were out 

path of direct flow. The floatable and nondescri

debris found in samples of bottom material for 

structural BMP is listed in table 4. Most of the fl

debris found in the samples consisted of natura

organic material (leaves and sticks), followed b

rette butts and plastic materials. Even with the u

hoods, which are intended to prevent floatable d

from leaving the catch basin, no debris was foun

ing in the catch basin at the conclusion of the m

ing period, and less than 1 percent by mass of s

of bottom material collected from the catch bas

identified as debris. This is likely the result of fl

debris circumventing the hoods during peak flow

important to note that the catch basin (136-06) 

twice the average drainage area of other catch b

within the study area, thus, the peak flows at the 

basin (136-06) were probably greater than flow

typical catch basins in the area. The presence of 

ing debris noted at the water surface of the prim

Table 4. Composition of bottom material collected from a deep-sumped hooded catch basin and each chamber of thre

separtors located along the Southeast Expressway, Boston, Massachusetts

[Values, except as noted, are in percent, by weight. kg, kilogram]

Material

Catch 

basin

136-06

Oil-grit separator 

136-01 739-01 749-01 Avera

Chamber Chamber Chamber Cham

One Two One Two One Two One 

Cigarette butts......................... 0.0 0.1 1.4 0.1 2.6 0.6 2.5 0.2 

Glass ....................................... .1 .1 .0 .1 .0 .0 .0 .1 

Plastic ..................................... .5 2.0 2.1 .8 .1 .3 1.4 1.1 

Natural organics...................... .1 .5 8.4 1.2 7.1 1.0 1.8 .9 

Metal....................................... .0 .1 .0 .0 .0 .0 .0 .0 

Paper ....................................... .0 .0 .0 .0 .7 .0 .0 .0 

Sediment ................................. 99.2 97.2 88.2 97.8 89.5 98.0 90.4 97.6 

Total amount of debris (kg) .... 234 343 134 159 31 397 385 300 
40 Effectiveness of Three Best Management Practices for Highway-Runoff Quality along the Southeast Expressway, Bosto

chamber of all of the separators, however, suggests that 

the hoods do not effectively prevent floatable debris 

from leaving the catch basins.

Reduction of

Debris and Litter

To document the relative ability of an oil-grit 

separator to retain large floatable particles, a debriscollection device was attached to the headwall outlet of 

the drainage system at station 739. Composites from 12 

runoff events were collected from April through June 

2000, when the monitoring period ended (fig. 17). A 

total of about 1.8 kg of material was retrieved from the 

collection structure for the twelve storms. The quantity 

of material collected for each storm increased with an 

increase in peak discharge. Gravel was removed from 

the collection structure twice, and both times bypass 

flow was recorded. About 71 percent (by mass) of total 

debris collected was associated with these two high 

runoff events. The bypass flow represented 7 percent 

and 1 percent of the total flow, respectively, for the two 

storms during this period. The quantity of material contained in the bypass flow, as opposed to the quantity 

of material passing through the separator, was not 

determined. The quantity of floatable debris retrieved 

from the collection structure from April through June 

2000 represented about 23 percent of the total estimate 

of floatable debris retained in the separator afte

months of operation. The percent of the total es

of floatable debris was reduced to about 8 perce

assuming the entire loads associated with the tw

storms were carried in bypass flow and did not 

through the separator or originate as a result of 

pension of previously retained debris in the sep

Thus, even under typical operating conditions, t

arators were not effective at retaining floatable 

Variability in Suspended-Sediment 

Concentration Samples

The concentrations of suspended sedimen

discrete samples of runoff collected from the in

the separators ranged from 8.5 to 7,110 mg/L, a

centrations of suspended sediment in discrete sa

of runoff collected from the inlet of the catch ba

ranged from 32 to 13,600 mg/L. The concentrat

suspended sediment in discrete samples of runo

lected from the outlets of the separators ranged 

to 2,170 mg/L, and concentrations of suspended 

ment in discrete samples of runoff collected fro

the outlet of the catch basin ranged from 25.7 to 

7,030 mg/L. Results of analysis of the inlet and 

samples for each structural BMP are presented 

appendix 1, table 1A. The median EMCs for sus

sediment at the inlet and the outlet for the separ

station 136 were estimated to be 333 and 150 m

and 145 and 96 mg/L at station 739. The interq

range (25th percentile minus 75th percentile) of 

EMCs for suspended sediment for the inlet and 

outlet of the separator at station 136 was estima

be 362 and 180 mg/L, and 314 and 125 mg/L at 

739. The lower EMCs for suspended sediment 

tion 739 are likely due to the fact that a smaller 

of the drainage-area perimeter (outer edge of th

way) included an earth shoulder, which therefor

duced less eroded soil on the pavement. The me

EMCs for suspended sediment at the inlet and o

for the catch basin were estimated to be 280 an

mg/L, respectively. The interquartile range for E

for suspended sediment at the inlet and the outle

catch basin was estimated to be 340 and 196 m

respectively.

The results of the particle-size analysis o

ples collected from the inlet of each structural B

indicated that, generally, 50 percent or more of 

suspended sediment in highway runoff consiste

material less than 0.062 mm in diameter (fig. 12

which is consistent with the findings in other st

Yousef and others (1991) reported that 70 to 80 

CIGARETTE 

BUTTS

6%

32% PLASTICS

NATURAL 

ORGANIC MATERIALS

44%

GRAVEL

18%

Figure 17. Relative quantity and type of debris retained 

from April 2000 through June 2000 in a collection 

structure mounted on a outlet of an oil-grit separator 

located along the Southeast Expressway, Boston, 

Massachusetts.
Assessment of Best Management Prac

of the particles in highway runoff were less than 0.088 

mm in diameter. Prych and Ebbert (1986) noted that 

most of the suspended material was less than 0.062 mm 

in diameter for many urban-runoff conditions. In the 

Southeast Expressway BMP study, more than 90 percent (by mass) of the particles in typical oil-grit 

separator outlet samples were less than 0.062 mm in 

diameter. The variability in the fraction of suspended 

sediment greater than 0.062 mm in diameter for samples collected from the outlet of the catch basin was 

substantial compared to samples from the catch basin 

inlet. This variability was an indication of device performance under different flow regimes. For example, 

the concentration of particles greater than 0.062 mm in 

diameter tended to increase during higher catch-basin 

outlet flows.

Effectiveness of Oil-Grit 

Separators in Reducing 

Suspended-Sediment 

Concentrations

The efficiency of the two 1,500-gal oil-grit 

separators in reducing suspended-sediment concentrations varied considerably. For example, the range of 

suspended-sediment removal efficiencies for individual 

storms was between -98 percent to +95 percent at station 136, and between -94 percent to +90 percent at station 739. Shepp (1995) reported a mean individual 

storm efficiency of -21.2 percent and a mean group 

storm efficiency of -7.5 percent from an oil-grit 

separator installed on a 1-acre parking lot. Other than 

Shepp’s experiments, this author is not aware of any 

extensive testing of separators.

The principal factor affecting the efficiency of 

each device was retention time. Intense flows also 

affected the efficiency, but to a lesser extent. The ability 

of the separators to reduce suspended sediments characteristic of those along the Southeast Expressway was 

limited because the average particle size was less than 

0.062 mm in diameter, and the average retention time 

in the separators ranged from about one hour to less 

than a minute. Although the separator volume was 

greater than that of a single catch basin, combined 

flows from multiple catch basins fed each separator, 

thereby increasing flow, reducing settling time, and 

inhibiting capture of fine material (fig. 18C-D). Settling 

velocities for urban and highway sediments can range 

from 0.03 to 65 ft/h (Dorman and others, 1996); thus, 

fine-grain sediment requires several days under static 

conditions to completely settle out. This effect 

becomes clear when examining the data from th

study. For example, the average removal efficie

associated with storms less than 0.2 in. was 43 p

Individual removal efficiencies greater than 43 

for suspended sediment were observed in less th

percent of the storms at station 136 and less tha

percent of the storms at station 739. This increa

device efficiency is a function of retention time 

a function of active treatment of the stormwater

from small storms displaced previously retained 

water in which the suspended sediments were r

by settling during the static antecedent period. C

quently, the average efficiency ranged from abo

81 percent when the same storms were sorted a

ing to the antecedent period that ranged from le

a day to nearly six days (fig. 19). During this stu

median antecedent dry period was about 4.5 da

In a few cases, outflow loads of suspende

ment from the separators exceeded inflow loads

was likely the result of fine-grained bottom sed

that were previously captured becoming resusp

and discharged from the separators. These case

marked by periods of high-intensity rainfall and 

high storm flows. The detection and quantity of 

pended sediment was difficult to determine beca

amount of resuspended sediment may be small 

comparison to the overall load. The relative rete

time of the separators also affects the ability to 

and quantify resuspended sediment because a c

in the inflow suspended-sediment concentration

not immediately reflected in the outflow suspen

sediment concentrations. In fact, following high 

inflow suspended-sediment concentrations, it is 

uncommon for discrete outflow suspended-sedi

concentrations to be slightly higher than inflow 

suspended-sediment concentrations because a l

concentration of the smaller size fraction of sed

remains in suspension and disperses throughout 

device. The quantity of resuspended sediment m

differ from storm to storm, due to the difference

in prior storm characteristics. For example, a hi

intensity storm may mobilize the fine-grained se

retained in the separator over several small low

intensity storms, but subsequent high-intensity 

may cause no resuspension because little fine-g

sediment was available. Therefore, the absolute 

tion of resuspended sediment was limited to sto

which the suspended-sediment load discharged 

the separator exceeded the suspended-sediment 

entering the separator. 
42 Effectiveness of Three Best Management Practices for Highway-Runoff Quality along the Southeast Expressway, Bosto

0 0

4:37 4:53 5:09 5:25 5:41 5:57 6:13 6:29 6:45 7:01 7:17 7:33 7:49 8:05 8:22

TIME

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

CONCENTRATION OF SUSPENDED SEDIMENT, IN MILLIGRAMS PER LITER

CATCH BASIN INFLOW

D.

C.

A.

B. CATCH BASIN OUTFLOW

OIL-GRIT SEPARATOR INFLOW

OIL-GRIT SEPARATOR OUTFLOW

LESS THAN 0.062 MILLIMETER

0.062 TO 0.250 MILLIMETER

GREATER THAN 0.250 MILLIMETER

DISCHARGE

0.13

0.25

0.38

0.50

0.63

0.75

0.88

1.00

0

0.13

0.25

0.38

0.50

0.63

0.75

0.88

1.00

DISCHARGE, IN CUBIC FEET PER SECOND

0.03

0.06

0.09

0.12

0.15

0.18

0.21

0.24

0.03

0.06

0.09

0.12

0.15

0.18

0.21

0.24

0

0

Figure 18. Suspended-sediment concentration and associated particle-size distribution in 

water moving through a deep-sumped hooded catch basin and a 1,500-gallon oil-grit 

separator located along the Southeast Expressway, Boston, Massachusetts.
Assessment of Best Management Prac

The suspended-sediment load for the separator 

outlet exceeded the suspended-sediment load for 

the separator inlet, calculated directly from samples 

of suspended sediment without any water-column 

normalization, three times at each separator. The 

suspended-sediment load for the separator outlet, however, exceeded the normalized inlet load 14 and 13 

times for separators 136 and 739, respectively. Because 

the normalization technique may be in error by as 

much as 24 percent, the suspended-sediment load 

for the separator outlet exceeded the normalized 

suspended-sediment load for the separator inlet (with 

respect to the potential error) nine and seven times for 

separators 136 and 739, respectively. The suspendedsediment load for the outlet of separator 136 exceeded 

the normalized inlet load six times during the operating 

period for station 739. The range of 5-minute rainfall 

intensities and separator flows during these storms was 

0.04 to 0.23 in. and 0.46 to 0.97 ft3/s, respectively, at 

station 136; and 0.04 to 0.18 in. and 0.48 to 2.81 ft3/s, 

respectively, at station 739. During the monitoring 

period, storm flows in the separator at station 136 

exceeded 0.46 ft3/s 33 times, and storm flows in the 

separator at station 739 exceeded 0.48 ft3/s 22 times. 

The flows from separator 136 exceeded 0.46 ft3/s 24 

times during the operating period for station 739. The 

greater maximum flows through separator 739 were the 

result of a higher diversion-weir elevation and a larger 

drainage area. The amount of resuspended sediment 

estimated for separators 136 and 739 represented about 

8 percent of the final retained loads of suspended sediment. The frequency of instances in which outflow 

loads of suspended sediment exceeded inflow lo

not increase with the increase in captured sedim

either separator. The level of captured sediment 

second chamber of each separator, however, wa

eral inches below the baffle, which would be ou

flow path. 

Previous studies found resuspension of se

to be a common problem in separators that wer

located off-line (Schueler and Shepp, 1993). Un

stormwater can bypass the separator during high 

and the potential for flushing captured material

reduced if the separator is off-line. In this study, 

loads accounted for about 3 percent of the total 

suspended sediment for each separator. Bypass 

began when flows neared 0.4 and 1.9 ft3/s at sta

136 and 739, respectively. The difference betwe

points at which bypass flow began to occur at e

tion was attributed to the differences in the dive

weir height. Although the weir diverted a portio

stormwater to the bypass pipe, the flow through 

separator was not limited and the flow through 

device continued to increase with total flow. A d

in weir height would increase the volume of by

flow and reduce the frequency of resuspension 

ments; however, a reduction in weir height does 

necessarily eliminate the potential for resuspen

sediments. Sediments (less than 0.062 mm in d

ter), which settle under static conditions betwee

storm, will accumulate in the separators as long 

flows are reduced to the point where no resuspe

occurs. During most storms, a reduction in dive

weir height may satisfy this condition. Howeve

the diversion weir does not limit flow through th

rators, previously retained sediments (less than 

0.062 mm in diameter) could become resuspend

during the peak flow of a subsequent high inten

storm. Thus, the long-term operating efficiency 

separator would be reduced to a level similar to 

rator with a greater weir height. Furthermore, a

increase in bypass frequency will reduce overall 

performance because a portion of the coarse-gr

suspended sediment, typically mobilized during 

flows and easily retained by the separator, will b

the structure completely. In this study, coarse-g

suspended sediment was not observed in sampl

separator outflow during any hydrologic condit

The estimated quantity of retained suspen

sediment less than 0.062 mm in diameter relativ

total outlet load of suspended sediment for the 

tors at station 136 and 739, presumably consisti

RELATIVE OIL-GRIT SEPARATOR PERFORMANCE 

0

10

20

30

40

50

60

70

80

90

MEAN EFFICIENCY FOR PRECIPITATION 

ANTECEDENT DRY PERIOD (DAYS)

EVENTS

 LESS THAN 0.2 INCHES, IN PERCENT

0.3 1.9 4.8 5.4 12.0

Figure 19. The relation of antecedent dry period to mean 

efficiency of oil-grit separators for precipitation events less 

than 0.2 inches, along the Southeast Expressway, Boston, 

Massachusetts.
44 Effectiveness of Three Best Management Practices for Highway-Runoff Quality along the Southeast Expressway, Bosto

suspended sediment less than 0.062 mm in diameter 

and larger low-density particles, was 9 and 6 percent, 

respectively. Because the particle-size distribution of 

suspended sediment was similar for the two stations, 

the smaller retained percentage of bottom sediment less 

than 0.062 mm in diameter measured at station 739 

indicated that a greater amount of resuspension 

occurred at this station. This resuspension was likely 

attributed to greater flows caused by the higher diversion weir. The estimated quantity of suspended sediment that bypassed the separators compared to the 

amount of sediment resuspended at each station was 

about 20 percent higher at station 136 and about 16 

percent lower at station 739. Bypass flow occurred 

more frequently at the separator at station 136. If the 

separators were not located off-line, and if all sediments less than 0.062 mm in diameter were resuspended and discharged between storms, the efficiency 

of each device would have been reduced additionally 

by about 5 percent. Conversely, decreasing the diversion weir height to a point at which no resuspension 

occurred would cause an exponential increase in 

untreated bypass load and would have reduced the 

overall efficiency for each separator substantially more 

than 5 percent. Thus, without the ability to limit flow to 

less than 0.46 ft3/s through the device, changes in weir 

height will not cause a substantial benefit. Resuspension could be drastically eliminated by reducing the 

drainage area of the device by a factor of about five or 

by maintaining (cleaning) the device between storms. 

Neither option is cost effective or practical. 

The absolute difference between all of the inlet 

and outlet loads of suspended sediment for the separators was 35 percent for station 136 and 28 percent for 

station 739. The separators retained 477 kg of solids 

(after 14 months) at station 136 and 190 kg (after 10 

months) of solids at station 739, on the basis of volumetric assessments. The relative mass balance error 

((∑SUSPENDED SEDIMENT IN-∑SUSPENDED 

SEDIMENT OUT)=∑RETAINED BOTTOM 

MATERIAL) for the separators was about 12 percent at 

station 136, and 25 percent at station 739. The efficiency computed from the estimated mass of material 

retained in each separator at the conclusion of the monitoring period and from the total outflow load was 32 

percent at station 136 and 24 percent at station 739. 

The small difference between these results from the 

two methods used to estimate the efficiency of the separators indicates that the normalization of the inflow 

loads was reasonable. The estimated difference 

between the mass-balance approaches was with

cumulative uncertainties of the various measure

processes. In the combined-treatment system ev

in this study, if catch basins that provided prima

suspended-sediment treatment are assumed to h

average efficiency of about 41 percent, the sepa

reduced the suspended-sediment load by an add

18 percent with respect to the initial load on the 

pavement.

Effectiveness of Deep-Sumped 

Hooded Catch Basins in Reducing 

Suspended-Sediment 

Concentrations

The efficiency of the deep-sumped hoode

basin in removing suspended sediment for indiv

storms ranged from -114 to +97 percent. In sim

tests, where particle size, density, and concentra

were controlled, Lager and others (1977) found 

suspended-sediment removal efficiencies of 35 

percent over a flow range of 0.25 to 6.3 ft3/s for 

basins with 4-ft sumps. Catch basins with sump

ing from 0.5 to 5 ft in an urban area were found 

suspended-sediment removal efficiencies rangin

-10 to +97 percent (Aronson and others, 1983). 

Storm characteristics affected the hydrau

retention time, catch-basin turbulence, and the m

zation of sediment on the roadway. The average 

basin retention time was about 1 hour; however

tion times were as low as 37 seconds during bri

periods of peak flow. The catch basin lacked su

retention time, even during flows as low as 0.03 

retain suspended sediment less than 0.062 mm i

eter. Particles less than 0.062 mm in diameter in 

catch basin have been retained as the result of s

settling. In general, the catch basin retained hig

density, medium- and coarse-grained particles. 

the performance of the catch basin improved w

these respective particle sizes were mobilized in 

flows. Catch-basin performance declined as flow 

increased, catch-basin turbulence increased, and 

tion time decreased. Lager and others (1977) fo

93-percent reduction in catch-basin performanc

respect to small particles (0.250 to 0.100 mm in 

ter) over a flow range of 0.25 to 6.3 ft3/s in a cle

catch basin, but only a 60-percent reduction in p

mance with respect to heavy solids (greater than 

0.250 mm in diameter). 
Assessment of Best Management Prac

Resuspension of bottom sediments was caused 

by excessive turbulence within the catch basin during 

peak flows. The literature suggests that when the level 

of retained material approaches or exceeds 50 percent 

of the catch-basin sump depth, sediments are resuspended. In simulated tests, sediment that accumulated 

in catch basins did not affect removal efficiencies of 

suspended sediment until 40 to 50 percent of the storage depth was filled (Lager and others, 1977). In the 

Southeast Expressway BMP study, resuspension was 

detected during several storms, although the volume of 

sediment retained in the catch basin was less than 25 

percent of the sump depth at the conclusion of the monitoring period. Sequential suspended-sediment concentrations of discrete outflow samples were frequently 

found to be substantially greater than respective inflow 

concentrations during flows greater than 0.14 ft3/s. At 

this flow rate, the retention time of the catch basin was 

less than 6 minutes. Further increases in discharge 

during peak flow often diminished the retention time 

and caused sediments larger than 0.250 mm in diameter 

to become resuspended as illustrated in figure 18A-B. 

During seven storms, outflow loads of suspended sediment exceeded inflow loads because previously 

retained sediments were resuspended, mixed with suspended sediment from the inflow, and discharged from 

the catch basin. The range of 5-minute rainfall intensities and storm flows was 0.04 to 0.17 in., and 0.14 to 

0.69 ft3/s, respectively. Storm flows exceeded 0.14 ft3/s 

30 times during the monitoring period. The estimated 

amount of resuspended sediment represented 18 percent of the final retained load of suspended sediment. 

The frequency of cases where outflow loads of suspended sediment exceeded inflow loads did not 

increase with an increase in captured sediment volume 

in the catch-basin sump.

The total difference between the inlet and outlet 

loads for the catch basin was 39 percent. An estimated 

234 kg of solids was retained by the catch basin. The 

relative mass-balance error for the catch basin was -14 

percent. The efficiency computed from the estimated 

quantity of material retained at the conclusion of the 

monitoring period and from the total outflow load 

was 43 percent. The primary factor controlling the 

suspended-sediment removal efficiency of the catch 

basin was retention time. The efficiency for catch 

basins along roadways can vary depending on the 

drainage area, the particle-size distribution for 

suspended sediment, and device maintenance.

The particle-size distribution of suspende

ment measured in samples collected from the o

the catch basin was different from the particle s

suspended sediment measured in samples from 

arator inflow at station 136 (fig. 18B-C), which 

lected outflows from eight catch basins. Higher 

sustained concentrations of particles greater tha

0.062 mm in diameter in the combined catch-ba

outlet flows indicated a reduction in suspended 

ment removal efficiency in one or more of the c

basins within the separator drainage area. The p

mances of the catch basins could have been diff

from one another because the individual contrib

areas affected the quantity and rate of flow for e

catch basin. The contributing areas of the other 

basins were 50 percent less than the area of the 

tored catch basin, except for one area, which wa

50 percent larger and represented about 31 perc

the separator drainage area. The catch basin in t

larger area was located on a southbound emerge

pull-off lane. The entire right-side shoulder did 

have a curb and was subject to soil erosion duri

runoff events. In this location, the quantity of su

pended sediment and the particle-size distributi

could have been substantially different. The hig

flow, increased turbulence, and reduced retentio

would have negatively affected the performance 

single catch basin in removing suspended sedim

runoff from the larger contributing area. Theref

suspended sediment discharged from this single 

basin may have affected the particle-size distrib

the combined flows. Conversely, the performan

most catch basins within the separator drainage 

removing suspended sediment should have been 

to or higher than that of the monitored catch ba

because most of their contributing areas were sm

Annual catch-basin cleaning was accomp

with a mechanical bucket truck in the late fall o

This crane-mounted cleaning mechanism, also 

as an orange-peel excavator, consisted of four m

opposing jaws to remove retained bottom mater

without sump water. This method did not remov

the bottom material. In fact, fine material was lo

the bucket when it was raised from the sump. T

bined suspended-sediment load from the catch-

outlet, as estimated from the separator inflow, w

substantially different before and after annual c

basin cleaning. This finding indicated that the d

ences in the amount of retained bottom materia

catch basins located within the drainage areas o
46 Effectiveness of Three Best Management Practices for Highway-Runoff Quality along the Southeast Expressway, Bosto

stations 136 and 739 did not substantially affect catchbasin performance. Late winter or spring catch-basin 

maintenance may provide a greater benefit than fall 

maintenance because high-intensity rainfall, during 

summer thunderstorms can cause resuspension of 

bottom sediments in the catch basins, even when the 

volume of bottom material represents less than 25 

percent of the catch-basin sump.

Estimated Loads of 

Suspended Sediment in the 

Study Area

The estimated annual load of suspended sediment for the entire study area of highway pavement 

is about 29,000 kg. About 24,000 kg is discharged 

near the Malibu Beach and Tenean Beach embayments 

and the remaining 5,000 kg is discharged to the land 

surface where it infiltrates into the ground. These 

loads do not include an estimated 2,000 kg of sediment 

and other materials, retained annually by the five 

separators, which are assumed to be cleaned annually. 

Mechanized Street 

Sweeping

Mechanized street sweeping is an effective alternative to structural BMPs for reducing sediment and 

debris in commercial and urban areas (Young and 

others, 1996). Many variables can affect sweeping performance, such as, the number of passes made, road 

surface and curb condition, particle-size distribution, 

quantity of material on the road surface, interval 

between treatments, and the type of equipment used. 

Shoemaker and others (2000) noted that the total solidremoval efficiency for mechanical sweepers was 55 

percent between storms and as high as 93 percent for 

vacuum-assisted sweepers. However, sweeping 

between storms and multiple passes were necessary to 

attain efficiencies this high. Despite poorer overall performance, mechanical sweepers are more effective at 

picking up larger debris (greater than 0.40 mm in diameter) than vacuum-assisted sweepers. In addition, 

vacuum-assisted sweepers have the disadvantage of 

low operation speeds which make them impractical for 

highway applications (Young and others, 1996). 

The effectiveness of sweeping was assess

by evaluating the differences between suspende

sediment loads for each BMP inlet for storms b

and after sweeping relative to storm precipitatio

totals. The highway was swept three times durin

study period. The first sweeping occurred in Jun

prior to the activation of station 739 and during 

week dry period. The second sweeping was don

March 16, 2000, and all stations were operating

collection at each station was discontinued befo

final scheduled sweeping. The particle-size distr

of sweeping samples is presented in appendix 1

table 1E. Figure 14B-D illustrates the effects of 

sweeping on suspended-sediment loads for each 

tural BMP. No substantial differences were obs

between the pre-sweeping and post-sweeping in

loads of the catch basin and the inlet loads of th

rator at station 136 for the initial June 1999 swe

Substantial increases in inlet loads for both BM

station 136 were observed after the March 16, 2

sweeping. Visual observations of the northboun

way shoulder in the vicinity of this station prior 

subsequent storm indicated that the sweeper’s r

brushes contacted and destabilized the soil near 

edge of the pavement, from which large amoun

sediment were released and mobilized during th

sequent storms. Conversely, the suspended-sedi

load measured in samples from the separator in

station 749 was reduced relative to previous sto

similar size. Furthermore, inlet and outlet suspe

sediment loads for station 749 were similar for t

two storms, which indicated that coarse materia

absent. Sweeping-equipment limitations preclu

the reduction of fine-grained sediment loads, w

typically dominated the suspended-sediment lo

The effectiveness of street sweeping was 

tatively assessed by evaluating the differences a

the particle-size distribution of sweeper sample

bottom-sediment samples collected in the catch 

and the weighted average of bottom-sediment s

collected from the three separators (fig. 20). Th

particle-size distribution of pavement sweeping

closely resembled the particle-size distribution 

catch-basin sediments in all size classes less tha

in diameter. Pavement sweepings had a lower c

tration of particles greater than 0.5 mm in diam

than that of bottom sediment collected from the 

separators. 
Assessment of Best Management Prac

0

5

10

15

20

25

30

<0.062 0.125<0.062 0.25<0.125 0.5<0.25 1<0.5 2<1 4<2 8<4 16<

SIZE CLASS, IN MILLIMETERS

DISTRIBUTION, IN PERCENT

AVERAGE SWEEPINGS

CATCH BASIN BOTTOM MATERIA

OIL-GRIT SEPARATOR

BOTTOM MATERIAL

On the basis on these data, the greatest benefit of 

annual street sweeping was the removal of particles 

greater than 8 mm in diameter that were not routinely 

mobilized during storm flows. Except for reducing the 

clean-out frequency for the catch basins and separators, 

frequent sweeping (several times a month) would provide little water-quality benefit beyond that offered by 

the existing structural BMPs along the Southeast 

Expressway. Sweeping provided little water-quality 

benefit for the Southeast Expressway because the highway lacks curbing that would provide a physical 

boundary to trap debris and sediment, and because the 

equipment did not remove the dominant particles 

(that is, particles less than 0.062 mm in diameter), 

efficiently. 

Variability of Concentrations of 

Chemical Constituents in 

Sediment

Sieved bottom sediments from the three 

1,500-gal oil-grit separators were analyzed for highway-related inorganic and organic constituents. Concentrations of inorganic constituents were determined 

by the EPA 3050 analytical method; a second method, 

XRAL analytical method ICP70, was used for analysis 

of selected samples. Constituent-concentration 

are listed in appendix 1, table 1G. Bismuth (Bi) 

Tungsten (W) were the only constituents not fo

any of the samples at a detection limit of less th

10 ppm by either analytical method. Mercury (H

not found in any of the samples at a detection li

1 ppm by the EPA 3050 analytical method; the 

method did not analyze for Hg. Antimony (Sb) 

only constituent not detected by the EPA 3050 

cal method, but it was detected by the XRAL m

In some cases, tin (Sn), and silver (Ag), and ph

rus (P) were not detected by the EPA 3050 anal

method, although they were detected by the XR

method. 

In general, concentrations of inorganic co

ents generated by each method were similar. W

use of these digestive techniques, the constituen

are weakly sorbed with the solid phase and are n

of the mineral matrix are measured. Many envir

tal factors, such as low pH, low redox, low diss

oxygen, or high ionic strength may consequentl

these weakly bound elements to repartition into 

solved phase (Breault and others, 2000). Measur

of low dissolved oxygen in the water column of 

separators during the summer and measuremen

high specific conductance (an indicator of ionic 

Figure 20. Average size distribution of pavement sweepings collected from a mechanical sweeper in contrast to the 

distribution of a bottom-sediment sample collected from a deep-sumped hooded catch basin and the weighted-aver

particle-size distribution of samples collected from three 1,500-gallon oil-grit separators along the Southeast Expres

Boston, Massachusetts.
48 Effectiveness of Three Best Management Practices for Highway-Runoff Quality along the Southeast Expressway, Bosto

strength) during winter maintenance periods were common. Therefore, high concentrations of trace elements 

measured in samples of bottom sediments indicate that, 

under favorable conditions (that is, in some state of 

equilibrium with the bottom sediments), the overlying 

water column may have become enriched with trace 

elements. These constituents would then be easily 

transported from the separators once they were 

redistributed to the dissolved phase.

Concentrations for all inorganic constituents 

were typically higher for the sediment fraction less 

than 0.062 mm in diameter, except for Cr and Na in all 

samples, and As and Sn in one sample. Beryllium (Be) 

was the only constituent not detected in sediment fractions greater than 0.062 mm in diameter. With a few 

exceptions, concentrations of Sb, As, Cd, and Ag were 

only found in the sediment fraction of less than 

0.062 mm in diameter. Results of chemical analysis for 

inorganic elements in bottom sediment relative to particle size are illustrated in figure 10. The disproportional 

differences between concentrations of inorganic constituents relative to grain size are well documented 

(Forstner and Wittmann, 1981; Salomons and Forstner, 

1984; Horowitz and Elrick, 1987, 1988; Horowitz, 

1991). In general, sediment surface area and traceelement concentrations tend to increase with a decrease 

in sediment-grain size. Furthermore, the silt- and claysized particle group contains more clay minerals, 

which typically have higher sorptive capacities. The 

potential effectiveness of the separators in reducing 

loads of inorganic constituents was several times less 

(as much as an order of magnitude depending on the 

constituent relation to grain size) than its effectiveness 

in reducing suspended sediment (consisting of fineand coarse-grained material); most of the suspended 

sediment entering the separators was less than 

0.062 mm in diameter, and the concentrations of inorganic constituents in the sediments less than 0.062 mm 

in diameter were about 2 to 10 times higher than the 

concentrations of inorganic constituents in sediments 

greater than 0.062 mm in diameter.

Concentrations of TOC, PCBs, and PAHs were 

detected in all sediment samples and size fractions. 

Concentrations of organic constituents did not follow 

the same pattern as the inorganic constituents. Results 

of chemical analysis of organic compounds in bottom 

sediments relative to particle size are presented in 

figure 11. Concentrations of TOC were similar for the 

solid fraction less than 0.062 mm in diameter and 

greater than 2.00 mm in diameter. However, estimated 

concentrations of TOC for the entire solid fract

than 2.00 mm in diameter were as much as one o

magnitude lower than for the fraction greater th

2.00 mm in diameter. The greater amount of TO

the solid fraction greater than 2.00 mm in diame

mainly attributed to natural organic particles (le

and asphalt particles. Total PAH and PCB comp

were found in larger concentrations in the solid f

greater than 2.00 mm in diameter than in the so

tion less than 2.00 mm in diameter. The greates

affecting concentrations of semivolatile organic 

pound (SVOCs) in the solid phase is the conten

organic carbon (Lopes and Dionne, 1998). The 

size of mineral particles, unless they have an or

coating, is not a significant factor affecting SVO

centrations (Witkowski and others, 1987). Thus

stantial differences in the TOC content of the si

fractions less than 2.00 mm and greater than 2.0

in diameter may explain the PCB and PAH distr

Furthermore, this would indicate that the PCB a

PAH concentrations in the solid fraction less th

0.062 mm in diameter would be similar to the c

trations in the solid fraction greater than 2.00 m

diameter; they might be greater in the smaller si

tion because of the effects of the increased surfa

Therefore, the potential effectiveness of the sep

to reduce loads of organic constituents was seve

times less (as much as an order of magnitude) t

ability to reduce suspended sediment because (a

of the suspended sediment entering the separato

less than 0.062 mm in diameter, (b) only about 

cent of the bottom material retained in the sepa

was greater than 2 mm in diameter, and (c) the 

tors did not indefinitely retain floatable debris, w

may contain concentrated levels of organic com

Local soils can generate as much as 30 pe

of suspended sediment entrained in highway ru

(Gupta, 1981). Local soils are deposited on the 

way between storms by wind erosion or hydrau

sion of the roadway shoulder and adjacent areas 

to similar forces, or directly deposited on the roa

automobiles. Average constituent concentration

bottom sediments in the three separators and w

on the basis of the distribution for the three part

size fractions were estimated from constituent c

trations of sieved samples. These data are contr

to background soil samples representing coasta

Massachusetts (Shacklette and Boerngen, 1984

figure 21. Concentrations of Cr, Cu, Pb, Ni, and 

typical constituents of highway runoff (Young a
Assessment of Best Management Prac

Aluminum Arsenic Barium

Beryllium Calcium Cobalt

Chromium Copper Iron Potassium

Lanthanum

Magnesium Manganese

Molybdenum Sodium Nickel Lead Scandium Strontium Titanium

Vanadium YttriumZinc Zirconium

CONSTITUENT

0.01

1,000,000

0.02

0.05

0.1

0.2

0.5

1

2

5

10

20

50

100

200

500

1,000

2,000

5,000

10,000

20,000

50,000

100,000

200,000

500,000

CONSTITUENT CONCENTRATIONS, IN MILLIGRAMS PER KILOGRAM

EXPLANATION

Detection limit

25th percentile

Median

75th percentile

interquartile range outside the quartile

Data value less than or equal to 1.5 times 

interquartile range outside the quartile

and more than 1.5 times the

Outlier data value less than or equal to 3 

interquartile range outside the quartile

Outlier data value more than 3 times the

Station 136

Station 739

Station 749

others, 1996), were as much as one order of magnitude 

greater in the bottom sediments from the separators 

than in local soils. Magnesium (Mg) concentrations in 

bottom sediment were about 2,000 times greater than 

in local soils. Concentrations of other constituents were 

either within their ranges in the soil or were less than in 

the soil. These data indicate that about 15 percent of the 

highway-affiliated metals could be attributed to local 

soils.

Reduction of Chemical 

Constituent Loads 

Discharged in Storm Flows

Samples for the analysis of concentration

inorganic and organic constituents were collecte

inlet and the outlet of each structural BMP duri

runoff events that reflected most seasonal variat

during the monitoring period. EMCs of chemic

Figure 21. Comparison of local soil chemistry to samples collected from oil-grit separators located along the 

Southeast Expressway, Boston, Massachusetts.
50 Effectiveness of Three Best Management Practices for Highway-Runoff Quality along the Southeast Expressway, Bosto

biological constituents are presented in appendix 1, 

table 1H. Total precipitation for the storms ranged from 

0.34 to 0.74 in.; most of the storms produced more precipitation than the average for all storms during the 

monitoring period. The individual and average RPDs 

between the inlet and the outlet (inlet minus outlet) 

concentrations for selected constituents for each structural BMP for four storms is illustrated in figure 22. 

The average RPD for concentrations of sedimentassociated constituents for the catch basin ranged from 

-29 to +42 percent. The average RPD for concentrations of trace metals was about 25 percent. The average 

RPD for concentrations of organic constituents was 

typically less than 20 percent and even negative in several cases, except for oil and grease, which was near 30 

percent. The average RPD for concentrations of sediment-associated constituents for the separators ranged 

from -129 to +44 percent at station 136, and -47 to +21 

percent at station 739. The average RPD for concentrations of trace metals was about 30 percent at station 

136, and about 15 percent at station 739. The average 

RPD for concentrations of organic constituents for both 

separators was commonly less than about 10 percent 

and negative in several cases.

Under ideal conditions, the RPD could be considered the main measure of efficiency of each structural BMP; however, the RPD does not represent the 

efficiency for the BMPs because the initial samples collected at the outlet do not represent water from the 

sampled storm, but water from the previous storm. Furthermore, the final inlet samples were not represented 

in the final outlet samples. For example, if we assume 

the following circumstances:

(a) the frequency of sampling was proportional to 

flow;

(b) each pair of samples represented one device 

volume; and

(c) the device exchanged its volume 20 times over 

the course of a storm,

Then the initial outlet sample would not be represented 

in the initial inflow sample and the final inflow sample 

would not be represented in the final outlet sample. 

Thus, as much as a 10 percent error (2 samples divided 

by 20) could be expected in the RPD. Furthermore, the 

total dissolved solid concentrations for the storm, 

which included all of the material that would ne

settle out of solution by gravity, should be simil

the inlet and outlet samples for each device und

sampling conditions. EMCs of total dissolved s

collected from the inlet and outlet at the separat

however, were commonly within 14 percent, an

EMCs of total dissolved solids collected from t

and outlet of the catch basin were as high as 57 p

these large differences indicate that the samples 

represented different sources of water. This was 

demonstrated during the March 17, 2000, storm

which the rain turned to snow in the final hours 

storm and deicing compounds were applied to t

roadway surface. The last two inlet samples at t

separator at station 739 contained high concent

of total dissolved solids which were not in the o

samples; thus, the RPD for EMCs of total disso

solids increased to nearly 80 percent.

The calculated RPD between inlet and ou

EMCs for sediment-associated constituents for 

structural BMP was probably too large, because 

concentration of suspended sediment in all four 

was greater than the median EMC of suspended 

ment. The March storm accounted for about 18 

of the total inlet load of suspended sediment for 

catch basin for the 14-month monitoring period

EMCs for suspended sediment for each BMP fo

four storms accounted for 9 to 23 percent of the 

load of suspended sediment measured during th

toring period. Furthermore, the RPD for concen

of each constituent for the separators does not i

the effects of the primary stormwater treatment 

vided by the catch basins. For example, if the R

between inflow and outflow EMCs of Pb for the 

basins within the drainage area of a separator is 

cent, and the RPD between inflow and outflow 

of Pb for the separator itself is 20 percent, the a

reduction of initial highway concentrations of P

the separator is actually only 14 percent. Theref

RPDs between the inflow and the outflow EMC

constituents sampled in this study should not be 

sidered as the actual reduction of constituent co

trations by the separators.
Assessment of Best Management Prac

DEEP-SUMPED HOODED CATCH BASIN (STATION 136)

SOC(-143)

1,500-GALLON OFF-LINE OIL-GRIT SEPARATOR (STATION 739)

9/30/1999

1/10/2000

3/17/2000

6/2/2000

AVERAGE

COD Cd(-648) (-154)

EXPLANATION

1,500-GALLON OFF-LINE OIL-GRIT SEPARATOR (STATION 136)

-148

-100

-80

-60

-40

-20

0

20

40

60

80

100

-100

-80

-60

-40

-20

0

20

40

60

80

100

-100

-80

-60

-40

-20

0

20

40

60

80

100

RELATIVE PERCENT

DIFFERENCE OF REMOVAL

RELATIVE PERCENT

DIFFERENCE OF REMOVAL

RELATIVE PERCENT

DIFFERENCE OF REMOVAL

Dissolved solids

Chemical oxygen demand

Petroleum hydrocarbons

Oil and grease

Ammonia

Nitrate plus Nitrite (dissolved)

Phosphorus

Suspended organic carbon

Arsenic

Cadmium

Chromium

Copper

Iron

Lead

Manganese

Nickel

Zinc

Polycyclic aromatic hydrocarbons

Polychlorinated byphenyls

Figure 22. Relative percent differences between inlet and outlet event mean concentrations of selected 

highway runoff constituents for a deep-sumped hooded catch basin and two 1,500-gallon oil-grit 

separators located along the Southeast Expressway, Boston, Massachusetts.
52 Effectiveness of Three Best Management Practices for Highway-Runoff Quality along the Southeast Expressway, Bosto

Additionally, the RPD for EMCs of sedimentassociated constituents for the separators was probably 

too large, because the sediment-associated constituent 

concentrations were not normalized (that is, they were 

not normalized to the average solid-phase constituent 

concentration in the water column); thus, sedimentassociated constituents in the size fractions greater than 

0.062 mm in diameter were not sampled in proportion 

to their average concentration. As discussed earlier, 

inlet loads of suspended sediment that were not normalized would be overestimated. This discrepancy is 

important because several of the storms produced 

above-average concentrations of suspended sediment 

containing large concentrations of coarse-grained particles. Although the size-fraction analysis of bottom sediment indicated that sediment-associated constituents 

had less affinity for the sediment-size fraction greater 

than 0.062 mm in diameter, coarse-grained sediments 

were readily retained by the separators; thus, overestimating the sediment-associated constituents related to 

the coarse-grained fraction creates a positive bias in the 

device efficiency. 

The following example, which assumes the 

respective trace elements are sorbed entirely on the 

solid phase, explains these potential effects. Theoretical inlet EMCs of Cu, Pb, Mn, and Zn were estimated 

from sieved bottom-sediment concentrations collected 

from the separators, and from the EMCs of suspended 

sediment and from information about the particle-size 

distributions. The average RPDs for the theoretical and 

the observed concentrations at the inlet of the separator 

were 37 percent for Cu, 22 percent for Pb, 32 percent 

for Mn, and 18 percent for Zn for four storms. The 

average percent of each constituent estimated for the 

size fraction greater than 0.062 mm relative to the total 

solid-phase concentration would be about 13 percent 

for Cu, 13 percent for Pb, 30 percent for Mn, and 12 

percent for Zn. During the January and March storms, 

the suspended-sediment concentrations and particlesize distributions were substantially different; the concentrations of each constituent estimated for the size 

fraction greater than 0.062 mm in diameter relative to 

the total solid-phase concentration were as high as 29 

percent for Cu, 30 percent for Pb, 61 percent for Mn, 

and 29 percent for Zn. Normalizing the suspendedsediment fraction greater than 0.062 mm in diameter to 

the sampling point for each storm by using experimental water-column data, reduced the concentrations by 

up to 65 percent. Thus, the inlet concentrations of each 

constituent associated with particles greater tha

0.062 mm normally retained by the device were 

estimated. Consequently, the normalized RPD b

the theoretical concentrations for the inlet of th

rator and observed concentrations for the outlet 

separator for the January and March storms sho

oretically be reduced by as much as an addition

percent for Cu, 11 percent for Pb, 10 percent fo

and 9 percent for Zn. The effect on the RPD for 

constituent depended upon the particle-size distr

of the sample and that constituent’s association 

particle size. 

The removal of inorganic and organic con

ents was impaired by the same factors that affec

removal of suspended sediment by the structura

in this study. The removal efficiency for inorgan

organic constituents was probably less than the 

suspended-sediment removal efficiency, becaus

sediment fraction (less than 0.062 mm in diame

onto which these constituents generally sorbed 

removed during flowing conditions in either dev

Although higher concentrations of PCBs and PA

were detected in the size fraction greater than 2

in diameter, concentrations of PCBs and PAHs 

believed to be similar in the sediment fraction le

0.062 mm in diameter due to the effects of incr

available surface area. Because the retained par

greater than 2.00 mm in diameter represent abo

percent of the total bottom material in the catch 

and about 6 percent of the total bottom material 

separators, and because both devices were not c

of retaining low-density floatables that containe

concentrations of TOC, the removal efficiency f

organic constituents could have been an order o

nitude less than the overall suspended-sediment 

removal efficiency. Furthermore, given that spe

conductance is a general measure of the total di

solids in solution, the lack of difference betwee

median and interquartile ranges of specific cond

tance values measured in samples of collected f

inlet and outlet of each structural BMP indicate

the devices were not effective at reducing disso

constituents (fig. 23). It should be noted that oth

ies have found that a high proportion of trace m

highway runoff are dissolved (Dupuis and other

1985). In this study, about 35 percent of the Cr, 

cent of the Ni, 15 percent of the Mg, 10 percent 

Cu, and 8 percent of the Zn as measured in EMC

samples collected in January 2000 and processe
Assessment of Best Management Prac

(358) (457) (374) (378) (301) (241)

739-02 (OUTLET)

739-03 (INLET)

136-02 (OUTLET)

136-03 (INLET)

136-04 (OUTLET)

136-05 (INLET)

STATION

10

1,000,000

20

30

40

50

70

100

200

300

400

500

700

1,000

2,000

3,000

4,000

5,000

7,000

10,000

20,000

30,000

40,000

50,000

70,000

100,000

200,000

300,000

400,000

500,000

700,000

SPECIFIC CONDUCTANCE SAMPLE MEASUREMENTS, IN

MICROSEIMENS PER CENTIMETER 

EXPLANATION

25th percentile

Median

75th percentile

Data value less than or equal to 1.5 ti

 the interquartile range outside the qu

interquartile range outside the quarti

and more than 1.5 times the 

Outlier data value less than or equal t

interquartile range outside the quarti

Outlier data value more than 3 times 

(358) Number of observations

within 24 hours of the initial sample collection were 

dissolved. In addition, the distribution of trace elements 

within the bottom sediment of the structural BMPs 

depends partly upon biochemical and geochemical 

conditions that increase concentrations of dissolved 

trace elements. For example, both Ellis and others 

(1987) and Morrison and others (1990) measured 

increases in dissolved concentrations of Cd, Cu

and Zn in catch-basin water caused by conditio

resulting from decomposition of organic matter 

sump sediment.

Loads for chemical and biological constit

were not estimated because insufficient data we

collected to accurately characterize the tempora

Figure 23. Specific conductance of suspended-sediment concentration samples collected from a deep-sumped ho

catch basin and two oil-grit separators located along the Southeast Expressway, Boston, Massachusetts.
54 Effectiveness of Three Best Management Practices for Highway-Runoff Quality along the Southeast Expressway, Bosto

spatial variability in the runoff. For example, the suspended-sediment concentrations for the four storms, 

which were also sampled for chemical and biological 

constituents, represented about 5 percent of the storms 

that occurred during the monitoring period, but as 

much as 21 percent of the overall suspended-sediment 

load during the monitoring period. Because the ratio of 

chemical loads to suspended-sediment loads, however, 

was likely similar to the ratio of chemical concentrations to suspended-sediment concentrations, use of the 

limited chemical data would overestimate the chemical 

loads.

Reduction of FecalIndicator Bacteria

Concentrations of fecal and Enterococci bacteria 

were found throughout the storms at the inlet of each 

oil-grit separator. This result indicates that the pavement washoff process was inefficient or that there was 

continuous source of bacteria in the drainage area. Discrete concentrations of fecal and Enterococci bacteria 

collected during five storms are presented in appendix 

1, table 1I. EMCs of Enterococci bacteria for samples 

collected during individual storms were within 36 percent of each other, and EMCs of fecal bacteria were 

within 90 percent of each other. In general, subcomposites of Enterococci bacteria for samples collected 

during individual storms varied from each other by as 

much as 500 percent and subcomposites of fecal bacteria varied from each other by 200 percent to more than 

an order of magnitude.

Concentrations of fecal-indicator bacteria were 

greatest in the fall and the early winter. An abrupt 

decrease in fecal and Enterococci bacteria concentrations in samples collected in March coincided with 

winter applications of deicing compounds. EMCs of 

fecal and Enterococci bacteria for samples collected in 

March were as much as an order of magnitude and 95 

percent lower than EMCs of fecal and Enterococci bacteria collected in the fall, respectively. Since deicing 

applications ceased around April, warmer and longer 

antecedent conditions may have affected June bacteria 

concentrations. This temporal distribution of fecalindicator bacteria is similar to that found in oth

way runoff studies (Kobriger and Geinopolos, 1

In about half of the storms, concentrations of fe

indicator bacteria were lower in initial first-flus

samples. One possible explanation is the initial 

entering the separators was essentially the supe

of the catch basins, and sediment-affiliated bact

may have settled during the antecedent period. 

quent bacteria concentrations increased because 

ment water mixed with the catch-basin water, a

possibly disturbed bottom sediments. The catch 

and the separator particularly provide an enviro

that is thermally stable, free from ultraviolet lig

enriched in TOC and nutrients—factors that no

enhance bacteria survivability. Bacteria have be

found to survive in storm sewers for at least 13 

and in sediment exposed to air for up to 49 day

(Kobriger and Geinopolos, 1984). Thus, the pot

for resuspension of sediments in each device an

lization of roadside sediment may provide a con

source of bacteria.

The efficiency of the structural BMPs tes

this study to reduce fecal-indicator bacteria con

tions was not quantified; however, these device

most likely ineffective for this purpose. Bacteri

removal efficiency is affected by the BMPs’ sho

retention time and inability to remove suspende

ment less than 0.062 mm in diameter. Individua

coliform bacteria cells are less than 0.002 mm i

eter (Schueler, 1999) and have settling characte

similar to clay particles (Coyne and others, 199

Schillinger and Gannon (1982) reported that 50 

of the bacteria in stormwater were not associate

sediments, and about 70 to 85 percent of associ

bacterial cells adhered to sediment particles les

0.030 mm in diameter. Consequently, each BM

likely to retain a quantity of fecal-indicator bac

proportional to its volume after a storm. Absolu

removal is dependent on the survivability of fec

indicator bacteria prior to the subsequent storm 

potential for export during the subsequent storm
Sum

SUMMARY

The USGS, in cooperation with the Federal 

Highway Administration and the Massachusetts 

Highway Department (MassHighway), began a 

study in November 1998 to determine the effectiveness 

of three best management practices (BMPs) in 

reducing suspended-sediment loads and related constituents along the Southeast Expressway in Boston, 

Massachusetts. The study area included about 2 mi of 

the Southeast Expressway, which represents about 0.06 

percent of the total area of the Neponset drainage basin 

and the Boston Harbor Coastal Subbasin. Primary 

treatment for highway stormwater runoff was provided 

by 209 catch basins. One 3-chambered 4,500-gal offline oil-grit separator, and four 2-chambered 1,500-gal 

off-line oil-grit separators provided additional stormwater treatment. Each separator includes a diversion 

weir positioned near the inlet of the separator that 

directs a portion of the flow to a bypass pipe during 

high flows. Mechanized street sweeping is conducted 

annually following the winter maintenance period. 

The BMPs examined in this study included a single 

catch basin, three 1,500-gal oil-grit separators, and 

mechanical street sweeping. 

Automatic-monitoring techniques were used to 

characterize the temporal and spatial variability in 

suspended-sediment transport through each structural 

BMP. Water samples were collected, and continuous 

measurements of selected hydrologic, water-quality, 

and meteorology parameters were made from April 

1999 through June 2000 for the catch basin and one of 

the separators (station 136), and from August 1999 

through June 2000 for the second separator (station 

739). The third separator was not continuously monitored. Samples for the analysis of suspended sediment 

and water quality were collected flow-proportionally at 

the inlet and outlet of each structural BMP automatically. The inlet and outlet flows for each device were 

sampled during four storms for analysis of chemical 

constituents. Discrete samples for the analysis of bacteria were collected flow-proportionally from a second 

dedicated automatic sampler at the inlet of each separator during five storms. Samples of large buoyant 

particles and other debris (greater than 6 mm in 

ter) were collected at the outlet of a separator (s

739) during 12 storms. 

Samples of bottom material were collecte

from three separators in November 1998, and fr

December 1999 through January 2000. The dep

bottom material was assessed in each structural 

prior to the first scheduled cleaning, during the 

tion of bottom material, and at the conclusion o

monitoring period. Samples of bottom material 

determinations of density were collected in the 

basin and each chamber of the separators. Samp

bottom sediment collected for chemical analysi

each separator in November 1998 were compos

proportion to the estimated volume of retained m

in each separator. Samples of bottom sediment 

ing litter and identifiable metal objects) collecte

chemical analysis in December 1999 through Ja

2000 were wet-sieved into size classes of less th

0.062 mm in diameter, between 0.062 mm and 

2.00 mm in diameter, and greater than 2.00 mm 

diameter. The contents of the bottom material w

visually identified and placed in general catego

Samples of street sweepings were collected from 

mechanical sweepers while in the vicinity of th

monitoring stations.

Quality-control data indicated that most d

were within the accumulative uncertainties of th

ous measurement, sampling, and analytical pro

Those data also indicated that particles greater t

0.062 mm in diameter were not evenly distribut

throughout the water column at the inlet of the 

tors. Loads of suspended sediment at the inlets 

separators would have been overestimated with

adjustment in concentration. Therefore, an adju

equation was developed to normalize the mean 

tration of suspended sediment in water samples 

lected at the fixed sampling location at the inlet 

separators. This equation was based on concent

and particle-size distribution of suspended sedim

collected in the water column of the drainage p

flows characteristic of observed field conditions

A distinct pattern of bottom-material dep

was initially observed for each separator; howe

the volume of material in each chamber increas
56 Effectiveness of Three Best Management Practices for Highway-Runoff Quality along the Southeast Expressway, Bosto

time, the distribution of the bottom material became 

more uniform. The estimated volume of retained 

bottom material in the separators at the conclusion of 

the study in contrast to the estimated volume of 

retained bottom material in the separators after threeyears of operation without any maintenance indicate 

that the estimated rate of bottom-material accumulation 

was about two times greater during the study period at 

station 136 and at station 739 and about seven times 

greater at station 749, than during the first three years 

of operation. The actual increase in the estimated rate 

of bottom-material accumulation is uncertain because 

the density of the bottom material for the first three 

years of operation was unknown and suspendedsediment data were not available prior to this study. 

One possible explanation for the increase in the rate of 

bottom-material accumulation during the study, or perhaps more specifically, the lack of accumulation during 

the first three years of operation, is that a single (or 

multiple) storm(s) resuspended a portion of the bottom 

material retained in the separators during the first three 

years of operation and flushed the suspended materials 

from the device; thus, the rate of accumulation would 

have been distorted by the loss of retained bottom 

material.

The particle-size distribution of bottom material 

varied substantially between the catch basin and the 

separators. Most bottom material in the catch basin 

(about 83 percent) and in the primary chamber of the 

separators (a weighted average of 85 percent) was 

coarse-grained (greater than 0.25 mm in diameter), 

whereas a greater amount of sediment in the secondary 

chamber of the separators was fine-grained (a weighted 

average of about 50 percent was less than 0.25 mm in 

diameter). The percentages of sediment particles found 

in each size class were similar, with respect to sample 

location, for each separator. In contrast, the percentages of particles found in each size class, for classes 

less than 0.062 mm in diameter and greater than 

0.5 mm in diameter, were substantially different for the 

two chambers of the separators. In general, the primary 

chamber of the separators contained higher percentages 

of coarse material, whereas finer and less dense particles were found in the second chamber. About 17 percent of the material found in the separators and about 7 

percent of the material found in the catch basin was 

less than 0.062 mm in diameter. 

Visual observations suggested that the separators 

were effective in removing floatable debris; however, 

the distribution of potentially floatable debris in bottom 

materials relative to each chamber, and the quan

debris collected at the outlet of a separator, indi

that the devices can be effective only if they are 

regularly. The absence of debris in the catch ba

the conclusion of the monitoring period and the 

ence of floatable debris found in each separator 

cated that the catch-basin hoods were not effect

reducing floatable debris.

The concentrations of suspended sedimen

discrete samples of runoff collected from the in

the separators ranged from 8.5 to 7,110 mg/L, a

centrations of suspended sediment in discrete sa

of runoff collected from the inlet of the catch ba

ranged from 32 to 13,600 mg/L. The concentrat

suspended sediment in discrete samples of runo

lected from the outlets of the separators ranged 

to 2,170 mg/L, and concentrations of suspended 

ment in discrete samples of runoff collected fro

outlet of the catch basin ranged from 25.7 to 

7,030 mg/L. The particle-size distribution of sa

collected from the inlet of each structural BMP 

cated that more than half of the suspended sedim

consisted of particles less than 0.062 mm in dia

The two separators treated about 98 perce

the stormwater within their contributing area. T

vidual suspended-sediment removal efficiencies 

from between -98 to +95 percent at station 136

-94 percent to +90 percent at station 739. The op

efficiencies for the respective monitoring period

the separators were 35 percent at station 136 an

percent at station 739. The average removal-effi

associated with storms less than 0.2 in., howeve

ranged from about 32 to 81 percent. This increa

efficiency was a function of retention time rathe

active treatment of the stormwater. The separato

tion 136 retained 477 kg and the separator at sta

739 retained 190 kg of solids. The efficiency co

from the measured mass of material retained in 

arators at the conclusion of the monitoring peri

from the total outflow load of suspended sedim

32 percent at station 136 and 24 percent at stati

The small difference between the two methods 

estimate the efficiency of the separators indicate

the flow-weighted normalization of the inflow l

was a reasonable approach. The estimated mass

balance difference was within the cumulative u

tainties of the various measurement processes. T

mary factor controlling the suspended-sedimen

removal efficiency of each structural BMP was 

tion time. In the combined treatment system in 
Sum

study, where catch basins provided primary suspendedsediment treatment, the separators reduced the mass 

of the suspended sediment from the pavement by about 

an additional 18 percent (with an assumed average 

catch-basin efficiency of about 41 percent).

Despite the presence of a bypass pipe at the 

inflow to the separator, previously captured sediments 

were resuspended and discharged from the separators 

nine times at station 136 and seven times at station 739. 

Resuspension of sediments was detected at and above 

rainfall intensities of 0.04 in. per 5-minute interval and 

flows greater than about 0.46 ft3/s at each station. 

Stormflows from the separator at station 136 exceeded 

0.46 ft3/s 33 times compared to 22 times for station 739 

during the monitoring period. The stormflows from 

separator 136 exceeded 0.46 ft3/s 24 times during the 

same 10-month operating period. The amount of resuspended sediment estimated for both separators represented about 8 percent of the suspended-sediment loads 

retained at the end of the monitoring period. The estimated quantity of suspended sediment that bypassed 

the separators at station 136, where bypass flow 

occurred more frequently, and station 739 was about 20 

percent higher and about 16 percent lower, respectively, than the amount of sediment (less than 

0.062 mm in diameter) resuspended. Without the ability to limit flows through the device to 0.46 ft3/s or less, 

changes in the diversion-weir height would not substantially affect the device performance. Sediments 

subject to resuspension represented a small fraction of 

the retained bottom-material composition, and a portion of coarse-grained sediments, readily retained by 

the separator and mobilized during peak flows, would 

bypass the device. Resuspension could be virtually 

eliminated by reducing the device drainage area by a 

factor of about five or performing maintenance (cleaning) between storms, but neither option is cost effective 

or practical. 

The individual removal efficiencies for the catch 

basin ranged from -114 to +97 percent. The average 

catch-basin retention time was about 1 hour; however, 

retention times were as low as 37 seconds during brief 

periods of flow. Resuspension of bottom sediments was 

detected during several storms, although the depth of 

bottom sediment retained in the catch basin was less 

than 25 percent of the sump depth at the conclusion of 

the monitoring period. The frequency of cases in which 

resuspension was detected did not increase with an 

increase in captured sediment. The estimated am

of resuspended sediment represented 18 percen

final mass of retained sediment. 

The operating efficiency for the 14-mont

monitoring period for the catch basin was 39 pe

and the catch basin retained an estimated 234 kg 

ids. The relative mass-balance error for the catc

was -14 percent. There was no substantial diffe

between combined loads of suspended sedimen

the catch-basin discharges, estimated from the s

tor inflows, several weeks before and after annu

catch-basin cleaning. This finding indicated tha

volumes of retained bottom material in the catch 

within the drainage areas of station 136 and 739 

not sufficient to substantially affect catch-basin 

mance. Removal of bottom sediments in the late 

or spring may be more beneficial than at other t

because high intensity rainfall, characteristic of 

summer thunderstorms, can cause resuspension 

bottom sediments in catch basins, even when th

volume of bottom material represents less than 

percent of the catch-basin sump. 

In this combined system, the efficiencies 

catch basin and separator were inversely related

suspended-sediment removal efficiency of the c

basin decreased with an increase in discharge, w

decreased retention time. Conversely, the separa

formance improved with an increase in discharg

spite of a decrease in retention time. This was d

part, to a change in the particle-size distribution 

periods of greater flows. During low flow, large

cles settled in the catch basins while finer mater

entered the separator. While the separator volum

greater than that of a single catch basin, the com

flow from multiple catch basins discharged to e

arator, which reduced the retention time and inh

the capture of fine material. As flow increased, 

ever, sediment from roadway and particle size t

to increase as coarse-grained material was disch

from the catch basin, which subsequently impro

separator performance.

Suspended-sediment loads for the entire 

area were estimated on the basis of the long-ter

age annual precipitation and the estimated inlet 

outlet loads of the two separators. The estimated 

suspended-sediment load for the entire study ar

about 29,000 kg. About 24,000 kg of this total d

charged near Malibu Beach and Tenean Beach e

ments, and the remaining 5,000 kg discharged t
58 Effectiveness of Three Best Management Practices for Highway-Runoff Quality along the Southeast Expressway, Bosto

land surface, where it infiltrated into the ground. These 

loads do not include an estimated 2,000 kg of sediment 

retained by the five separators.

The effectiveness of mechanical street sweeping 

was assessed by evaluating the differences between 

suspended-sediment loads of structural BMPs before 

sweeping and after sweeping relative to storm precipitation totals. The effectiveness was also assessed by 

evaluating the differences between the particle-size 

distribution of sweeper samples and bottom-sediment 

samples collected in the catch basin and the weighted 

average of bottom-sediment samples collected from the 

three separators. The particle-size distribution of 

sweeping samples closely resembled the particle-size 

distribution of the catch-basin sediments in all size 

classes below 4 mm in diameter. The concentration of 

particle sizes greater than 0.5 mm in diameter in 

sweeper samples was higher than averaged concentrations of bottom sediment collected from the separators. 

On the basis of these data, the greatest benefit of annual 

street sweeping was the removal of particles greater 

than 8 mm in diameter that were not mobilized routinely during storm flows. Except for reducing the frequency of cleaning of catch basins and separators, 

frequent pavement sweeping (several times a month) 

would probably provide little additional water-quality 

benefit beyond those of the existing structural BMPs 

along the Southeast Expressway, due in part to the lack 

of curbing at the highway edge that would provide a 

physical boundary to trap debris and sediment. Also the 

sweeper was not effective at removing particles less 

than 0.062 mm in diameter, which composed the 

dominant particle-size group on the roadway surface. 

Concentrations of inorganic constituents in 

sieved bottom sediments from three separators were 

typically higher for sediments less than 0.062 mm in 

diameter. Concentrations of total organic carbon (TOC) 

in sieved bottom sediments were similar for sediments 

less than 0.062 mm in diameter and sediments greater 

than 2.00 mm in diameter. Conversely, concentrations 

of polychlorinated biphenyls (PCB) and polyaromatic 

hydrocarbons (PAH) were typically higher for sediments greater than 2.00 mm in diameter. A substantial 

difference in the TOC content of sediments greater than 

2.00 mm in diameter and less than 2.00 mm in diameter 

may explain the PCB and PAH distribution and further 

indicate that the PCB and PAH concentrations in 

bottom sediments less than 0.062 mm in diameter are 

similar to the concentrations in the bottom sediments 

greater than 2.00 mm in diameter, if not greater 

because of the effects of the surface area. There

the potential effectiveness of the catch basins an

separators to reduce loads of inorganic and orga

constituents was several times less (as much as a

of magnitude) than their ability to reduce loads 

pended sediment (consisting of natural organics

fine- and coarse-grained material) because (a) m

the suspended sediment entering the structural B

was less than 0.062 mm in diameter, (b) only ab

percent of the retained bottom material in the ca

basin and 6 percent of the retained bottom mate

the separators was greater than 2 mm in diamet

(c) neither type of device was completely capab

retaining low-density floatable debris that conta

concentrated levels of TOC and organic compo

The average relative percent difference (R

for concentrations of trace metals and organic 

constituents between the inlet and the outlet (in

minus outlet) of the catch basin ranged from -2

+42 percent. The average RPD for concentratio

of sediment-associated constituents for the inlet 

the outlet of the separators ranged from -129 to 

+44 percent at station 136, and -47 to +21 perce

at station 739. The average RPD for concentrati

of trace metals was about 30 percent at station 

and about 15 percent at station 739. The averag

RPD for concentrations of organic constituents 

both separators was commonly less than about 

percent and negative in several cases. These RP

were probably larger than normal because the 

precipitation totals for the four storms were gre

than the average precipitation total for storms d

the monitoring period, and likewise, the EMCs 

suspended sediment for each structural BMP in 

all four storms were greater than the median 

EMCs of suspended sediment for each BMP du

the monitoring period. In fact, the quantity 

of suspended sediment during the four storms 

accounted for 9 to 23 percent of the overall susp

sediment load for each BMP during the monito

period. Additionally, because sediment-associat

constituents collected from the inlet of the sepa

were not normalized to the water column, the 

portion of constituents associated with sedimen

greater than 0.062 mm in diameter was not sam

in proportion to the mean concentration. Exami

of constituent-sediment relations suggests that a 

substantial amount of highway-related constitue

was either in the dissolved form and not subjec

to treatment by simple gravity separation, or wa
References 

associated with particles less than 0.062 mm in 

diameter, which commonly passed through these 

structural BMPs. Loads for chemical and biological 

constituents were not estimated because insufficient 

data were collected to characterize the temporal and 

spatial variability accurately; however, the ratio of 

chemical loads to suspended-sediment loads was likely 

similar to the ratio of chemical concentrations to 

suspended-sediment concentrations. 

The efficiency of the structural BMPs tested in 

this study to reduce concentrations of fecal-indicator 

bacteria was not quantified; however, the structural 

BMPs are probably ineffective in reducing fecalindicator bacteria concentrations because bacteria 

share the same settling characteristics as particles less 

than 0.062 mm in diameter. Absolute bacteria removal 

in each device is dependent on the fecal-indicator 

bacteria survivability prior to the storm and the potential for exportation during the storm. Fecal and 

Enterococci bacteria were found throughout the entire 

storm at the inlet of each separator; this finding indicated that the pavement-washoff process was inefficient or that there was continuous source of bacteria 

in the drainage area.

The findings of this study on the effectiveness of 

deep-sumped hooded catch basins, 1,500-gal off-line 

oil-grit separators, and mechanized street sweeping 

were based on the physical and environmental conditions during the study. Many of the conditions at this 

site were unique in Massachusetts, specifically the 

movable zipper barrier and the substantial average 

daily traffic volume. Studies of other highways that 

have lower traffic volumes, different particle-size 

distributions, and different concentrations of suspended 

sediment may produce other results.

REFERENCES CITED

American Public Health Association–American Water 

Works Association–Water Pollution Control 

Federation (APHA–AWWA–WPCF), 1992, 

Standard methods for the examination of water 

and wastewater (18th ed.): Washington, D.C., 

American Public Health Association, American 

Water Works Association and Water Pollution 

Control Federation, 1,100 p. 

_____1995, Standard methods for the examinat

water and wastewater (19th ed.): Washingt

D.C., American Public Health Association, 

variously paged.

ASTM, 2000, Standard test method for determi

sediment concentration in water samples: A

Designation D 3977-97, p. 395–400.

Aronson, G.L., Watson, D.S., and Pisano, W.C.

Evaluation of catch basin performance for 

storm water pollution control: U.S. Environ

Protection Agency, EPA/600/14, 78 p.

Barrett, M.E., Malina, J.F., and Charbeneau, R.J

Effects of highway construction and operat

water quality in an ephemeral stream in the 

Texas area: Federal Highway Administratio

Texas State Department of Transportation F

Report FHWA/TX-96/1943-3, 131 p.

Bent, G.C., Gray, J.R., Smith, K.P., and Glysson

2000, Measuring sediment in highway runo

Geological Survey Open-File Report 00-49

Beschta, R.L., 1980, Turbidity and suspended se

relationships, in Watershed Management S

sium, Proceedings: Boise, Idaho, American 

Society of Civil Engineers, Irrigation and D

age Division, July 21–23, 1980, variously p

Breault, R.F., and Granato, G.E., 2000, A synop

technical issues for monitoring trace eleme

highway and urban runoff: U.S. Geological 

Open-File Report 00-422, 67 p.

Breault, R.F., Reisig, K.D., Barlow, L.K., and W

P.K., 2000, Distribution and potential for a

biological effects of inorganic elements an

organic compounds in bottom sediment, Lo

Charles River, Massachusetts: Water-Resou

Investigations Report 00-4180, p. 70.

Brown, W.M., 1973, Streamflow and turbidity i

Mad River Basin, Humboldt and Trinity Co

California: U.S. Geological Survey WaterResources Investigations Report 36-73, 57 

Brown, W.M., and Ritter, J.R., 1971, Sediment 

port and turbidity in the Eel River Basin, 

California: U.S. Geological Survey Water-S

Paper 1986, 70 p.

Buckler, D.R., and Granato, G.E., 1999, Assess

logical effects from highway-runoff constit

U.S. Geological Survey Open-File Report 9

45 p
60 Effectiveness of Three Best Management Practices for Highway-Runoff Quality along the Southeast Expressway, Bosto

Coyne, M.S., Gilfillen,R.A., Rhodes, R.W., and 

Blevins, R.L., 1995, Soil and fecal coliform trapping by grass filter strips during simulated rain. 

Journal of Environmental Quality 10 p. 279–284.

Cramer, G.H., and Hopkins, W.C., 1981, The effects 

of elevated highway construction on water quality 

in Louisiana wetlands: Federal Highway 

Administration, Louisiana State Department of 

Transportation Final Report FHWA/LA-81/148, 

45 p.

Driscoll, E.D., Shelley, P.E., and Strecker, E.W., 1990, 

Pollutant loadings and impacts from highway 

stormwater runoff , v. IV, Research report data 

Appendix: Federal Highway Administration Final 

Report FHWA-RD-88-009, 143 p. 

Dorman, M.E., Hartigan, J.P., Steg, R.F., and 

Quasebarth, T.F., 1996, Retention, detention, and 

overland flow for pollutant removal from highway 

stormwater runoff, v. I, Rresearch report: Federal 

Highway Administration Final Report FHWA-RD96/095, 179 p.

Dupuis, T.V., Bertram, P., Meyer, J., Smith, M., 

Kobriger, N., and Kaster, J., 1985, Effects of highway runoff on receiving waters, v. I: Federal 

Highway Administration Report FHWA/RD84/062, 28 p.

Edwards, T.K., and Glysson, G.D., 1999, Field methods for measurement of fluvial sediment: U.S. 

Geological Survey Techniques of Water-Resources 

Investigations, book 3, chap, C2, 89 p.

Ellis, J.B., Revitt, D.M., Harrop, D.O., and Beckwith, 

P.R., 1987, The contribution of highway surfaces 

to urban stormwater sediments and metal loadings: 

Science of the Total Environment, v. 59, p. 339–

349. 

Fishman, M.J., 1993, Methods of analysis by the U.S. 

Geological Survey National Water Quality 

Laboratory—Determination of inorganic and 

organic constituents in water and fluvial sediments: U.S. Geological Survey Open-File Report 

93-125, 217 p.

Fishman, M.J., and Friedman, L.C., 1989, Methods for 

determination of inorganic substances in water and 

fluvial sediments: U.S. Geological Survey 

Techniques of Water-Resources Investigations, 

book 5, chap. A1, 545 p.

Fishman, M.J., Raese, J.W., Gerlitz, C.N., and 

Husband, R.A., 1994, U.S. Geological Sur

approved inorganic and organic methods fo

analysis of water and fluvial sediment, 195

U.S. Geological Survey Open-File Report 9

55 p.

Foreman, W.T., Connor, B.F., Furlong, E.T., Va

D.G., and Merten, L.M., 1995, Methods of 

sis by the U.S. Geological Survey National 

Quality Laboratory—Determination of org

nochlorine pesticides and polychlorinated b

nyls in bottom sediment by dual capillary-c

gas chromatography with electron-capture 

detection: U.S. Geological Survey Open-Fi

Report 95-140, 78 p.

Forstner, U., and Wittmann, G.T.W., 1981, Meta

tion in the aquatic environment: New York

Springer-Verlag, 486 p. 

Gippel, C.J., 1995, Potential of turbidity monito

measuring the transport of suspended solid

streams: Hydrologic Processes, v. 9, p. 83–

Gray, J.R., Glysson, G.D., and Turcios, L.M., 2

Comparability and reliability of total suspe

solids and suspended-sediment concentratio

U.S. Geological Survey Water-Resources 

Investigations Report 00-4191, 14 p.

Gupta, M.K., Agnew, R.W., and Kobriger, N.P., 

Constituents of highway runoff, v. 1, State-

art report: U.S. Federal Highway Administ

Report FHWA/RD-81/042, 111 p.

Guy, H.P., 1970, Fluvial sediment concepts: U.S

Geological Survey Techniques of Water-Re

Investigations, book 3, chap. C1, 55 p.

Guy, H.P., 1969, Laboratory theory and method

sediment analysis: U.S. Geological Survey 

Techniques of Water-Resources Investigati

book 5, chap. C1, 58 p.

Horowitz, A.J., and Elrick, K.A., 1987, The rela

stream sediment surface area, grain size, an

position to trace element chemistry: Applie

Geochemistry, v. 2, p. 437–451. 

Horowitz, A.J., 1991, A primer on sediment-tra

element chemistry, (2d ed.): Ann Arbor, M

Lewis Publishing Company, 136 p. 

Horowitz, A.J., and Elrick, K.A., 1987, The rela

stream sediment surface area, grain size, an

position to trace element chemistry: Applie

Geochemistry, v. 2, p. 437–451. 
References 

Horowitz, A.J., and Elrick, K.A., 1988, Interpretation 

of bed sediment trace metal data: methods for 

dealing with the grain size effect, in Lichtenberg, 

J.J., Winter, J.A., Weber, C.I. and Fradkin, L., 

(eds.), Chemical and biological characterization of 

sludges, sediments, dredge spoils, and drilling 

muds: American Society for Testing and Materials, 

Special Technical Publication 976, p. 114–128. 

Irwin, G.A., and Losey, G.T., 1978, Water-quality 

assessment of runoff from a rural highway bridge 

near Tallahassee, Florida: U.S. Geological Survey 

Water-Resources Investigations Report 79-1, 27 p.

Kobriger, N.P., and Geinopolos, A., 1984, Sources and 

migration of highway runoff pollutants—Research 

report, v. III: Federal Highway Administration 

Final Report FHWA/RD-84/059, 358 p.

Lager, J.A., Smith, W.G., and Tchobanoglous, G., 

1977, Catchbasin technology overview and assessment: U.S. Environmental Protection Agency 

Final Report, EPA-600/2-77-051, 128 p.

Lewis, Jack, 1996, Turbidity-controlled suspended sediment sampling for runoff-event load estimation: 

Water Resources Research, v. 32, no. 7, p. 2,299–

2,310.

Lopes, T.J., and Dionne, S.G., 1998, A review of semivolatile and volatile organic compounds in highway runoff and urban stormwater: U.S. Geological 

Survey Open-File Report 98-409, 67 p. 

McKenzie, D.J., and Irwin, G.A., 1983, Water quality 

assessment of stormwater runoff from a heavily 

used urban highway bridge in Miami, Florida: 

U.S. Geological Survey Water-Resources Investigations Report 83-4153, 45 p.

Morrison, G.M.P., Revitt, D.M., and Ellis, J.B., 1990, 

Metal speciation in separate stormwater systems: 

Water Science and Technology, v. 22, no. 10-11, 

p. 53–60.

Mudroch, A., and MacKnight, S.D., 1994, Handbook 

of Techniques for Aquatic Sediment Sampling (2d 

ed.): Boca Raton, Fla., Lewis Publishers, 236 p. 

Myers D.N. and Sylvester, M.A., 1997, National field 

manual for the collection of water-quality data—

Biological Indicators: U.S. Geological Survey 

Techniques of Water-Resources Investigations, 

book 9, chap. A7, variously paged.

Prych, E.A., and Ebbert, J.C., 1986, Quantity and quality of storm runoff from three urban catchments in 

Bellevue, Washington: U.S. Geological Survey 

Water-Resources Investigations Report 86-4000, 

85 p.

Reed, L.A., 1978, Effectiveness of sediment-co

techniques used during highway constructi

central Pennsylvania: U.S. Geological Surv

Water-Supply Paper 2054, 57 p. 

Salomons, W., and Forstner, U., 1984, Metals in 

Hydrocycle: New York, Springer-Verlag, 3

Schiffer, D.M., 1989, Effects of highway runoff 

quality of water and bed sediments of two 

lands in central Florida: U.S. Geological S

Water-Resources Investigations Report 88-

63 p.

Schillinger, J.E., and Gannon, J., 1982, Coliform 

attachment to suspended particles in Storm

U.S. Environmental Protection Agency, NT

83-108324. 106 p.

Schueler, T.R., 1999, Ways to kill ‘em: Watersh

Protection Techniques, v. 3, no. 1, p. 566–5

_____1997, Performance of oil-grit separators i

removing pollutants at small sites: Watersh

Protection Techniques, v. 2, no. 4, p. 539–5

Schueler, T.R., and Shepp, D., 1993, The qualit

trapped sediments and pool water within o

separators in suburban Maryland: Marylan

Department of the Environment and Metro

Washington Council of Governments Inter

Report, 47 p.

Shacklette, H.T., and Boerngen, J.G., 1984, Ele

concentrations in soils and other surficial m

of the conterminous United States: U.S. 

Geological Survey Professional Paper 1270

Shelton, L.R., and Capel, P.D., 1994, Guidelines 

collecting and processing samples of stream 

sediments for analysis of trace elements an

organic contaminants for the National Wate

Quality Assessment Program: U.S. Geolog

Survey Open-File Report 94-458, 20 p.

Shepp, D., 1995, Petroleum hydrocarbons in ur

runoff—A study overview: Maryland Depa

of the Environment, Department of Environ

Programs, Metropolitan Washington Counc

Governments, 47 p.

Shoemaker, L., Lahlou, M., Doll, A., and Cazen

2000, Stormwater best management practic

ultra-urban setting: selection and monitorin

Federal Highway Administration Report FH

EP-00-002, 287 p.
62 Effectiveness of Three Best Management Practices for Highway-Runoff Quality along the Southeast Expressway, Bosto

Sholar, C.J. and Shreve, E.A., 1998, Quality-assurance 

plan for the analysis of fluvial sediment by the 

northeastern region, Kentucky District Sediment 

Laboratory: U.S. Geological Survey Open-File 

Report 98-348, 20 p.

Smith, Kent, 1986, A budget analysis of turbidity and 

streamflow data, in Proceedings of the Fourth 

Federal Interagency Sedimentation Conference, 

March 24–27, 1986: Las Vegas, Nev., v. 2, 

p. 7-71–7-79.

Société Générale de Surveillance, 2001, XRAL 

Laboratories Services—ICP and ICPMS 

Multi-Element: accessed August 16, 2001, 

at URL http://www.sgs.ca/xral/services/

multiElement. html.

Spangberg, A. and Niemczynowicz, J. 1992, High resolution measurements of pollution wash-off from an 

asphalt surface: Nordic Hydrology, v. 23, p. 245–

256.

U.S. Environmental Protection Agency, 2000, Index to 

EPA test methods, May 2000 revised edition: 

accessed August 16, 2001, at URL http:// 

www.epa.gov/region01/oarm/testmeth.pdf.

_____1997, Method 1600—Membrane filter test 

method for enterococci in water: Washington, 

D.C., EPA/821/R-97/004, May 1997.

_____1986, Quality criteria for water: U.S. 

Environmental Protection Agency, EPA 440/5-86-

001, variously paged.

Wershaw, R.L., Fishman, M.J., Grabbe, R.R., a

Lowe, L.E., eds., 1987, Methods for the de

nation of organic substances in water and fl

sediments: U.S. Geological Survey Techniq

Water-Resources Investigations, book 5, ch

80 p.

Wilde, F.D., and Radtke, D.B., 1999, Technique

prevent sample contamination, in Wilde, F.

Radtke, D.B., Gibs, J. and Iwatsubo, R.T. (

National field manual for the collection of 

quality data: U.S. Geological Survey Techn

of Water-Resources Investigations, book 9, 

chap. A 4.0, variously paged.

Witkowski, P.J., Smith, J.A., Fusillo, T.V., and C

C.T., 1987, A review of surface-water sedim

fractions and their interactions with persist

manmade organic compounds: U.S. Geolo

Survey Circular 993, 39 p. 

Young, G.K., Stein, S., Cole, P., Kammer, T., Gr

F., and Bank, F., 1996, Evaluation and man

ment of highway runoff water quality: Fed

Highway Administration Final Report FHW

96-032, 480 p.

Yousef, Y.A., Lin, L., Sloat, J.V., and Kaye, K.Y

Maintenance guidelines for accumulated se

ments in retention/detention ponds receivin

way runoff in Tallahassee, Fla.: Florida Sta

Department of Transportation Final Report 

ER-47-91, 210 p.
Appendix 1. Summary Statistics and Analytical

Results from the Evaluations of Effectiveness for

Three Best Management Practices for

Highway-Runoff Quality along the Southeast

Expressway, Boston, Massachusetts
Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts 

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di

Monitoring location 136-02 (oil-grit separator outflow)

5-08-1999 1702 1,310 9 -- -- 1,080 650 

5-08-1999 1706 1,990 5 -- -- 962 1,200 

5-08-1999 1710 1,660 3 -- -- 923 900 

5-08-1999 1716 1,180 2 -- -- 880 700 

5-08-1999 1722 848 2 -- -- 826 500 

5-08-1999 1726 644 2 -- -- 761 370 

5-19-1999 2246 -- -- -- -- -- -- 

5-19-1999 2340 102 11 -- -- 1,700 75 

5-20-1999 0132 128 10 -- -- 2,050 120 

5-20-1999 0138 177 4 -- -- 1,760 160 

5-20-1999 0146 244 2 -- -- 1,330 200 

5-20-1999 0156 221 2 -- -- 962 200 

5-20-1999 0204 182 3 -- -- 728 190 

5-20-1999 0220 176 0 -- -- 577 160 

5-20-1999 0640 -- -- -- -- -- -- 

5-20-1999 0848 131 2 -- -- 855 130 

5-20-1999 0912 167 1 -- -- 920 150 

5-23-1999 2116 89 2 -- -- 1,020 50 

5-23-1999 2118 81 1 -- -- 1,030 50 

5-23-1999 2148 147 3 -- -- 1,000 110 

5-23-1999 2156 185 3 -- -- 837 180 

5-23-1999 2210 207 4 -- -- 606 180 

5-23-1999 2216 279 7 -- -- 409 200 

5-23-1999 2220 374 10 -- -- 289 220 

5-23-1999 2222 405 12 -- -- 252 220 

5-23-1999 2224 417 12 -- -- 229 210 

5-23-1999 2226 404 11 -- -- 211 200 

5-23-1999 2228 374 10 -- -- 207 190 

5-23-1999 2232 282 7 -- -- 203 150 

5-23-1999 2236 271 7 -- -- 195 140 

5-23-1999 2240 696 5 -- -- 196 130 

5-23-1999 2244 214 6 -- -- 191 120 

5-23-1999 2254 178 2 -- -- 185 110 

5-23-1999 2312 129 1 -- -- 180 90 

5-24-1999 0308 58 3 -- -- 376 55 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at m

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts

[ntu, nephelometric turbidity units;  ̊C, degrees Celsius; ft3/s, cubic feet per second; mg/L, milligrams per liter; mm, millimeters; μS/cm, microsiem

centimeter at 25 ̊C; %, percent; >, actual value is greater than value shown; --, no data]
Monitoring location 136-02 (oil-grit separator outflow)—Continued

5-24-1999 0314 84 3 -- -- 370 70 

5-24-1999 0320 69 4 -- -- 298 60 

5-24-1999 0330 63 2 -- -- 238 50 

5-24-1999 1422 251 3 -- -- 440 170 

5-24-1999 1416 -- -- -- -- -- -- 

5-24-1999 1520 241 1 -- -- 635 220 

5-24-1999 1522 246 5 -- -- 644 230 

5-24-1999 1636 716 10 -- -- 472 360 

5-24-1999 1640 748 6 -- -- 268 350 

5-24-1999 1648 490 3 -- -- 205 260 

5-24-1999 1730 187 1 -- -- 210 150 

5-24-1999 1830 106 2 -- -- 254 100 

5-24-1999 1858 145 3 -- -- 272 130 

5-24-1999 1920 136 3 -- -- 220 120 

7-01-1999 0236 97 -- -- -- 633 50 

7-01-1999 0238 131 -- -- -- 734 50 

7-01-1999 0258 229 -- -- -- 814 150 

7-01-1999 0304 319 -- -- -- 507 140 

7-01-1999 0310 289 -- -- -- 408 170 

7-01-1999 0318 263 -- -- -- 415 180 

7-01-1999 0344 208 -- -- -- 406 160 

7-01-1999 0404 170 -- -- -- 455 130 

7-01-1999 0602 373 -- -- -- 429 150 

7-01-1999 0606 639 -- -- -- 268 170 

7-01-1999 0610 543 -- -- -- 176 140 

7-01-1999 0612 448 -- -- -- 151 120 

7-01-1999 0620 264 -- -- -- 148 120 

7-01-1999 0628 188 -- -- -- 145 110 

7-01-1999 0642 128 -- -- -- 168 85 

7-01-1999 0710 95 -- -- -- 208 70 

7-01-1999 1014 85 -- -- -- 299 70 

7-01-1999 1104 171 -- -- -- 491 130 

7-01-1999 1112 193 -- -- -- 385 150 

7-01-1999 1126 177 -- -- -- 308 150 

7-01-1999 1154 136 -- -- -- 277 130 

7-06-1999 1704 127 -- -- -- 670 110 

7-06-1999 1708 336 -- -- -- 622 180 

7-06-1999 1716 204 -- -- -- 538 130 

7-06-1999 1738 147 -- -- -- 545 100 

7-06-1999 1844 82 -- -- -- 614 55 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 136-02 (oil-grit separator outflow)—Continued

7-06-1999 2136 83 -- -- -- 621 60 

7-06-1999 2210 77 -- -- -- 640 60 

7-13-1999 0656 -- -- -- -- -- -- 

7-13-1999 0658 -- -- -- -- -- -- 

7-19-1999 1654 165 -- -- -- 732 90 

7-19-1999 1706 146 -- -- -- 443 100 

7-19-1999 1720 64 -- -- -- 299 75 

7-19-1999 1728 107 -- -- -- 206 85 

7-19-1999 1754 60 -- -- -- 211 60 

7-19-1999 1818 31 -- -- -- 219 65 

7-19-1999 1910 -- -- -- -- 241 55 

7-19-1999 1920 -- -- -- -- -- -- 

7-20-1999 1319 255 -- -- -- 330 29 

7-23-1999 0100 197 -- -- -- 541 10 

7-23-1999 0102 515 -- -- -- 563 200 

7-23-1999 0106 429 -- -- -- 356 180 

7-23-1999 0108 321 -- -- -- 290 150 

7-23-1999 0112 211 -- -- -- 245 100 

7-23-1999 0120 138 -- -- -- 200 75 

7-23-1999 0130 65 -- -- -- 188 65 

7-23-1999 0142 49 -- -- -- 190 55 

7-23-1999 0150 43 -- -- -- 177 40 

7-23-1999 0158 47 -- -- -- 156 40 

7-23-1999 0208 52 -- -- -- 139 45 

7-24-1999 2026 467 -- -- -- 253 90 

7-24-1999 2028 405 -- -- -- 190 120 

7-24-1999 2030 425 -- -- -- 155 110 

7-24-1999 2032 335 -- -- -- 140 110 

7-24-1999 2036 217 -- -- -- 139 90 

7-24-1999 2042 136 -- -- -- 129 75 

7-24-1999 2108 216 -- -- -- 127 70 

7-24-1999 2112 143 -- -- -- 154 60 

7-24-1999 2116 151 -- -- -- 100 100 

7-24-1999 2122 104 -- -- -- 96 60 

7-24-1999 2146 62 -- -- -- 102 39 

7-25-1999 1358 35 -- -- -- 159 31 

7-25-1999 1640 81 -- -- -- 392 50 

7-25-1999 1644 206 -- -- -- 281 85 

7-25-1999 1648 173 -- -- -- 187 80 

7-25-1999 1654 119 -- -- -- 155 55 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 136-02 (oil-grit separator outflow)—Continued

7-25-1999 1706 65 -- -- -- 116 55 

7-27-1999 1254 16 -- -- -- -- -- 

8-06-1999 2126 10 -- -- -- 200 14 

8-06-1999 2128 12 -- -- -- 203 9 

8-06-1999 2204 -- -- -- -- -- -- 

8-14-1999 2136 119 -- -- -- 642 25 

8-14-1999 2138 190 -- -- -- 624 85 

8-14-1999 2140 236 -- -- -- 558 120 

8-14-1999 2142 260 -- -- -- 508 140 

8-14-1999 2144 255 -- -- -- 462 165 

8-14-1999 2146 252 -- -- -- 428 170 

8-14-1999 2148 262 -- -- -- 411 150 

8-14-1999 2150 242 -- -- -- 400 160 

8-14-1999 2152 328 -- -- -- 383 170 

8-14-1999 2154 238 -- -- -- 381 150 

8-14-1999 2156 217 -- -- -- 378 160 

8-14-1999 2158 208 -- -- -- 374 160 

8-14-1999 2200 210 -- -- -- 366 160 

8-21-1999 2006 -- -- -- -- -- -- 

8-21-1999 2118 30 -- -- -- 659 29 

8-22-1999 0652 32 -- -- -- 475 28 

8-26-1999 1724 11 -- -- -- 430 17 

8-26-1999 1726 7 -- -- -- 432 22 

9-06-1999 1136 91 -- -- -- 714 110 

9-06-1999 1152 288 -- -- -- 533 170 

9-06-1999 1206 237 -- -- -- 319 180 

9-07-1999 0238 120 -- -- -- 345 90 

9-07-1999 0404 103 -- -- -- 272 70 

9-07-1999 0410 244 -- -- -- 188 120 

9-07-1999 0416 190 -- -- -- 177 120 

9-07-1999 0446 103 -- -- -- 154 100 

9-07-1999 0518 67 -- -- -- 174 60 

9-08-1999 0922 116 -- -- -- 296 90 

9-08-1999 0938 153 -- -- -- 284 140 

9-08-1999 1002 127 -- -- -- 260 130 

9-08-1999 1014 87 -- -- -- 855 95 

9-08-1999 1058 112 -- -- -- 262 110 

9-10-1999 0752 178 -- -- -- 323 160 

9-10-1999 0814 157 -- -- -- 260 160 

9-10-1999 0822 360 -- -- -- 163 170 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 136-02 (oil-grit separator outflow)—Continued

9-10-1999 0826 407 -- -- -- 125 220 

9-10-1999 0838 227 -- -- -- 107 150 

9-10-1999 0906 98 -- -- -- 121 90 

9-10-1999 0954 130 -- -- -- 162 100 

9-10-1999 1004 172 -- -- -- 137 140 

9-10-1999 1148 -- -- -- -- -- -- 

9-10-1999 1442 70 -- -- -- 200 80 

9-10-1999 1450 139 -- -- -- 196 120 

9-10-1999 1500 132 -- -- -- 155 120 

9-10-1999 1508 158 -- -- -- 98 95 

9-10-1999 1520 106 -- -- -- 76 75 

9-15-1999 1850 -- -- -- -- -- -- 

9-15-1999 1936 55 -- -- -- 332 65 

9-15-1999 2004 78 -- -- -- 301 95 

9-15-1999 2026 90 -- -- -- 209 100 

9-15-1999 2052 73 -- -- -- 160 80 

9-15-1999 2112 57 -- -- -- 135 65 

9-15-1999 2136 46 -- -- -- 119 60 

9-15-1999 2220 37 -- -- -- 119 50 

9-15-1999 2320 34 -- -- -- 146 50 

9-15-1999 2346 43 -- -- -- 122 55 

9-16-1999 0006 48 -- -- -- 95 50 

9-16-1999 0020 44 -- -- -- 75 45 

9-16-1999 0038 36 -- -- -- 62 39 

9-16-1999 0052 31 -- -- -- 59 34 

9-16-1999 0948 145 -- -- -- 53 80 

9-16-1999 1016 71 -- -- -- 51 55 

9-16-1999 1228 47 -- -- -- 124 65 

9-16-1999 1412 101 -- -- -- 105 65 

9-16-1999 1520 182 -- -- -- 97 60 

9-16-1999 1536 83 -- -- -- 69 40 

9-16-1999 1604 50 -- -- -- 68 26 

9-16-1999 1634 32 -- -- -- 66 18 

9-16-1999 1654 139 -- -- -- 41 45 

9-16-1999 1822 50 -- -- -- 85 30 

9-22-1999 2334 36 -- -- -- 352 20 

9-22-1999 2336 36 -- -- -- 353 21 

10-06-1999 1426 12 -- -- -- 158 1.8 

10-18-1999 0712 31 -- -- -- 63 31 

10-18-1999 0714 31 -- -- -- 62 30 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 136-02 (oil-grit separator outflow)—Continued

10-20-1999 0820 152 -- -- -- 159 50 

10-20-1999 0854 131 -- -- -- 205 130 

10-20-1999 0908 155 -- -- -- 174 160 

10-20-1999 1204 113 -- -- -- 172 130 

10-20-1999 1216 163 -- -- -- 104 140 

10-20-1999 1234 136 -- -- -- 78 120 

10-23-1999 0208 -- -- -- 190 75 

10-23-1999 0240 99 -- -- -- 179 80 

10-23-1999 0302 77 -- -- -- 176 60 

10-23-1999 0330 53 -- -- -- 142 45 

10-23-1999 0346 50 -- -- -- 102 39 

10-23-1999 0404 48 -- -- -- 77 32 

10-23-1999 0418 44 -- -- -- 65 33 

10-23-1999 0444 36 -- -- -- 62 28 

10-26-1999 1530 16 -- -- -- 116 10 

11-02-1999 2340 149 1 -- -- 380 160 

11-02-1999 2358 152 2 -- -- 334 180 

11-03-1999 0020 119 2 -- -- 273 140 

11-03-1999 0042 96 4 -- -- 238 110 

11-03-1999 0106 81 3 -- -- 202 95 

11-03-1999 0122 83 5 -- -- 152 80 

11-03-1999 0136 75 6 -- -- 121 70 

11-03-1999 0146 65 4 -- -- 100 60 

11-03-1999 0158 52 10 -- -- 90 50 

11-03-1999 0208 46 4 -- -- 79 40 

11-03-1999 0218 36 2 -- -- 79 35 

11-03-1999 0234 38 3 -- -- 75 35 

11-03-1999 0244 37 3 -- -- 76 32 

11-03-1999 0256 50 3 -- -- 278 50 

12-20-1999 2307 44 -- -- -- 61 36 

12-20-1999 2330 -- -- -- -- -- -- 

12-20-1999 2344 -- -- -- -- -- -- 

12-21-1999 0019 -- -- -- -- -- -- 

12-21-1999 0047 -- -- -- -- -- -- 

12-21-1999 0058 -- -- -- -- -- -- 

12-21-1999 0118 -- -- -- -- -- -- 

12-21-1999 0300 -- -- -- -- -- -- 

12-21-1999 0332 -- -- -- -- -- -- 

1-10-2000 1956 -- -- -- -- -- -- 

1-10-2000 2012 -- -- -- -- -- -- 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 136-02 (oil-grit separator outflow)—Continued

1-10-2000 2032 -- -- -- -- -- -- 

1-10-2000 2057 -- -- -- -- -- -- 

1-10-2000 2158 -- -- -- -- -- -- 

1-13-2000 0922 -- -- -- -- -- -- 

1-13-2000 0951 -- -- -- -- -- -- 

1-13-2000 1007 -- -- -- -- -- -- 

1-16-2000 1002 -- -- -- -- -- -- 

1-16-2000 1039 -- -- -- -- -- -- 

1-20-2000 1930 66 -- -- -- 110,000 85 

1-27-2000 1530 65 -- -- -- 71,600 58 

1-31-2000 0348 -- -- -- -- -- -- 

1-31-2000 0406 30 -- -- -- 72,400 21 

1-31-2000 0428 -- -- -- -- -- -- 

1-31-2000 0429 46 -- -- -- 76,000 40 

1-31-2000 0445 562 -- -- -- 65,500 600 

1-31-2000 0521 -- -- -- -- -- -- 

1-31-2000 0524 405 -- -- -- 27,500 400 

1-31-2000 0543 -- -- -- -- -- -- 

1-31-2000 0558 379 -- -- -- 18,100 390 

1-31-2000 0618 -- -- -- -- -- -- 

2-14-2000 0753 363 -- -- -- 880 280 

2-14-2000 0813 265 -- -- -- 2,230 250 

2-14-2000 0838 247 -- -- -- 2,420 260 

2-14-2000 0857 269 -- -- -- 2,550 260 

2-14-2000 0924 285 0 -- -- 3,030 290 

2-14-2000 0932 451 5 -- -- 2,800 380 

2-14-2000 0935 935 8 -- -- 2,810 550 

2-14-2000 0938 1,050 -- -- -- 2,450 700 

2-14-2000 0948 979 -- -- -- 2,140 700 

2-14-2000 1018 643 -- -- -- 1,917 500 

2-14-2000 1029 467 -- -- -- 1,784 380 

2-14-2000 1104 373 -- -- -- 1,851 360 

2-14-2000 1122 351 -- -- -- 1,850 360 

2-14-2000 1140 340 -- -- -- 1,817 360 

2-14-2000 1152 423 -- -- -- 1,786 380 

2-14-2000 1156 583 -- -- -- 1,826 450 

2-14-2000 1201 654 -- -- -- 1,533 500 

2-14-2000 1212 629 -- -- -- 1,484 500 

2-18-2000 1455 97 -- -- -- 4,550 160 

2-18-2000 2138 588 -- -- -- 61,300 450 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 136-02 (oil-grit separator outflow)—Continued

2-18-2000 2142 -- -- -- -- -- -- 

2-18-2000 2145 441 -- -- -- 59,700 400 

2-18-2000 2148 377 -- -- -- 60,500 310 

2-18-2000 2218 532 -- -- -- 65,000 450 

2-25-2000 1440 46 -- -- -- 46,400 70 

2-25-2000 1507 643 -- -- -- 31,400 950 

2-25-2000 1524 1,090 -- -- -- 20,300 2,000 

2-25-2000 1544 1,020 -- -- -- 15,110 1,800 

2-25-2000 1604 854 -- -- -- 13,420 1,300 

2-25-2000 1619 707 -- -- -- 11,780 1,000 

2-25-2000 1639 599 -- -- -- 10,820 750 

2-25-2000 1659 537 -- -- -- 6,820 600 

2-25-2000 1713 499 -- -- -- 6,550 600 

2-25-2000 1727 422 -- -- -- 6,850 450 

2-25-2000 1744 399 -- -- -- 6,720 450 

2-25-2000 1927 271 -- -- -- 6,060 320 

2-25-2000 1948 250 -- -- -- 7,210 320 

2-25-2000 2008 292 -- -- -- 7,180 320 

2-25-2000 2100 273 -- -- -- 5,990 320 

2-25-2000 2122 239 -- -- -- 5,640 300 

2-25-2000 2201 207 -- -- -- 5,240 260 

2-25-2000 2219 188 -- -- -- 4,940 230 

2-25-2000 2243 172 -- -- -- 4,910 220 

2-26-2000 0711 105 -- -- -- 782 150 

2-26-2000 0728 -- -- -- -- 5,380 220 

2-27-2000 0810 -- -- -- -- 2,120 190 

2-27-2000 0827 -- -- -- -- 5,420 650 

2-27-2000 0848 -- -- -- -- 5,560 850 

3-28-2000 0439 103 3 1.17 1.76 28,800 110 

3-28-2000 0449 36 9 6.11 3.05 34,800 45 

3-28-2000 0457 9 48 22.58 25.81 35,500 10 

3-28-2000 0505 358 5 2.82 1.87 37,300 310 

3-28-2000 0510 564 3 1.14 1.47 27,100 500 

3-28-2000 0515 594 2 1.14 0.59 19,860 550 

3-28-2000 0525 650 3 1.49 1.11 14,230 650 

3-28-2000 0539 625 4 2.12 1.79 7,910 550 

3-28-2000 0551 452 3 1.64 1.46 5,640 400 

3-28-2000 0605 392 3 0.78 2.08 4,610 340 

3-28-2000 0615 362 3 1.42 1.27 3,540 310 

3-28-2000 0627 385 3 2.29 0.63 2,910 320 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 136-02 (oil-grit separator outflow)—Continued

3-28-2000 0641 433 2 1.21 .40 2,470 350 

3-28-2000 0654 408 2 1.66 .33 2,080 328 

3-28-2000 0659 313 2 .78 1.18 1,809 260 

3-28-2000 0705 727 11 8.58 2.62 1,908 380 

3-28-2000 0722 880 7 5.26 1.35 1,296 500 

3-28-2000 0738 666 5 4.03 .99 1,213 390 

3-28-2000 0754 330 6 4.62 1.33 1,027 230 

3-28-2000 0817 335 7 4.48 2.05 870 210 

3-28-2000 0921 283 3 2.09 .53 849 190 

3-28-2000 1106 189 6 5.24 .81 787 140 

3-28-2000 1453 141 2 1.47 .53 969 130 

3-28-2000 2136 123 6 4.80 1.20 1,989 160 

4-04-2000 0338 52 -- -- -- 1,782 75 

4-04-2000 0402 292 -- -- -- 2,080 280 

4-04-2000 1453 132 -- -- -- 1,919 200 

4-04-2000 1525 205 -- -- -- 2,120 250 

4-04-2000 1600 251 -- -- -- 2,300 320 

4-04-2000 1633 330 -- -- -- 2,220 440 

4-04-2000 1808 -- -- -- -- -- -- 

4-04-2000 2153 -- -- -- -- -- -- 

4-04-2000 0225 -- -- -- -- -- -- 

4-08-2000 2317 60 -- -- -- 2,350 130 

4-08-2000 2341 519 -- -- -- 2,630 440 

4-09-2000 0035 -- -- -- -- -- -- 

4-09-2000 0148 -- -- -- -- -- -- 

4-09-2000 0150 341 -- -- -- 2,250 330 

4-09-2000 0219 -- -- -- -- -- -- 

4-09-2000 0222 262 -- -- -- 1,621 230 

4-09-2000 0304 -- -- -- -- -- -- 

4-09-2000 0341 151 -- -- -- 1,035 160 

4-09-2000 0426 -- -- -- -- -- -- 

4-09-2000 0452 523 -- -- -- 634 310 

4-09-2000 0502 -- -- -- -- -- -- 

4-09-2000 0518 268 -- -- -- 382 170 

4-09-2000 0533 -- -- -- -- -- -- 

4-09-2000 0600 131 -- -- -- 345 95 

4-09-2000 0609 -- -- -- -- -- -- 

4-09-2000 0632 131 -- -- -- 304 100 

4-09-2000 0658 -- -- -- -- -- -- 

4-09-2000 0725 190 -- -- -- 310 120 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 136-02 (oil-grit separator outflow)—Continued

4-09-2000 0729 -- -- -- -- -- -- 

4-09-2000 0735 338 -- -- -- 235 170 

4-09-2000 0741 -- -- -- -- -- -- 

4-09-2000 0757 146 -- -- -- 213 95 

4-09-2000 0821 -- -- -- -- -- -- 

4-16-2000 0649 82 -- -- -- 1,474 90 

4-16-2000 0754 82 -- -- -- 1,128 100 

4-18-2000 1828 33 -- -- -- 1,090 50 

4-18-2000 1901 164 -- -- -- 1,415 180 

4-18-2000 1939 186 -- -- -- 1,040 200 

4-18-2000 2011 -- -- -- -- 807 180 

4-18-2000 2012 158 -- -- -- 807 180 

4-18-2000 2041 -- -- -- -- -- -- 

4-18-2000 2042 136 -- -- -- 604 140 

4-18-2000 2105 -- -- -- -- -- -- 

4-18-2000 2140 104 -- -- -- 394 110 

4-18-2000 2207 -- -- -- -- -- -- 

4-18-2000 2239 74 -- -- -- 331 80 

4-18-2000 2342 -- -- -- -- -- -- 

4-19-2000 0013 50 -- -- -- 324 60 

4-19-2000 0142 -- -- -- -- -- -- 

4-19-2000 0432 27 -- -- -- 386 40 

4-19-2000 0601 -- -- -- -- -- -- 

4-19-2000 0730 103 -- -- -- 483 140 

4-19-2000 0814 -- -- -- -- -- -- 

4-21-2000 1252 52 -- -- -- 509 90 

4-21-2000 1543 -- -- -- -- -- -- 

4-21-2000 1545 247 -- -- -- 1,231 310 

4-21-2000 1717 -- -- -- -- -- -- 

4-21-2000 1719 243 -- -- -- 1,031 310 

4-21-2000 1833 -- -- -- -- -- -- 

4-21-2000 1835 182 -- -- -- 725 240 

4-21-2000 1938 -- -- -- -- -- -- 

4-21-2000 1939 134 -- -- -- 552 180 

4-21-2000 1953 -- -- -- -- -- -- 

4-21-2000 2002 322 -- -- -- 263 230 

4-21-2000 2024 -- -- -- -- -- -- 

4-21-2000 2117 116 -- -- -- 207 110 

4-21-2000 2124 -- -- -- -- -- -- 

4-21-2000 2135 159 -- -- -- 175 120 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 136-02 (oil-grit separator outflow)—Continued

4-21-2000 2143 -- -- -- -- -- -- 

4-21-2000 2217 105 -- -- -- 146 85 

4-21-2000 2234 -- -- -- -- -- -- 

4-21-2000 2240 178 -- -- -- 131 100 

4-21-2000 2247 -- -- -- -- -- -- 

4-21-2000 2259 121 -- -- -- 112 85 

4-21-2000 2313 -- -- -- -- -- -- 

4-21-2000 2347 48 -- -- -- 115 40 

4-22-2000 0007 -- -- -- -- -- -- 

4-22-2000 0021 66 -- -- -- 107 50 

4-22-2000 0031 -- -- -- -- -- -- 

4-22-2000 0042 78 -- -- -- 93 60 

4-22-2000 0052 -- -- -- -- -- -- 

4-22-2000 0101 90 -- -- -- 89 60 

4-22-2000 0109 -- -- -- -- -- -- 

4-22-2000 0115 199 -- -- -- 83 100 

4-22-2000 0132 -- -- -- -- -- -- 

4-22-2000 0140 115 -- -- -- 106 75 

4-22-2000 0157 -- -- -- -- -- -- 

4-22-2000 0203 159 -- -- -- 93 80 

4-22-2000 0226 -- -- -- -- -- -- 

4-22-2000 0233 86 -- -- -- 87 55 

4-22-2000 0251 -- -- -- -- -- -- 

4-22-2000 0259 77 -- -- -- 85 50 

4-22-2000 0319 -- -- -- -- -- -- 

4-22-2000 0355 56 -- -- -- 111 50 

4-22-2000 0603 -- -- -- -- -- -- 

4-22-2000 0738 87 -- -- -- 218 80 

4-22-2000 1240 -- -- -- -- -- -- 

4-22-2000 1241 39 -- -- -- 189 40 

4-22-2000 1647 -- -- -- -- -- -- 

4-26-2000 0316 31 -- -- -- 347 32 

4-26-2000 0416 44 -- -- -- 673 55 

4-26-2000 0457 102 -- -- -- 943 120 

4-26-2000 0525 181 -- -- -- 789 200 

4-26-2000 0554 192 -- -- -- 554 190 

4-26-2000 0646 -- -- -- -- -- -- 

4-26-2000 0814 112 -- -- -- 484 160 

4-26-2000 0932 -- -- -- -- -- -- 

4-26-2000 1919 109 -- -- -- 503 170 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 136-02 (oil-grit separator outflow)—Continued

5-02-2000 0559 117 -- -- -- 1,166 80 

5-02-2000 0719 184 -- -- -- 816 72 

5-02-2000 0806 57 -- -- -- 1,280 190 

5-02-2000 0842 161 -- -- -- 1,043 220 

5-08-2000 1711 413 -- -- -- 1,143 180 

5-08-2000 1718 1,270 -- -- -- 1,220 600 

5-08-2000 1726 916 -- -- -- 953 450 

5-10-2000 1328 582 -- -- -- 892 350 

5-10-2000 1502 -- -- -- -- 655 180 

5-10-2000 2027 312 -- -- -- 655 180 

5-10-2000 2034 -- -- -- -- -- -- 

5-10-2000 2202 185 -- -- -- 282 130 

5-10-2000 2229 -- -- -- -- -- -- 

5-10-2000 2258 128 -- -- -- 118 75 

5-10-2000 2325 -- -- -- -- -- -- 

5-13-2000 2257 -- -- -- -- -- -- 

5-18-2000 1847 61 -- -- -- 241 11 

5-18-2000 1916 196 -- -- -- 660 110 

5-18-2000 1954 178 -- -- -- 550 120 

5-19-2000 0646 -- -- -- -- -- -- 

5-19-2000 0717 234 -- -- -- 490 160 

5-19-2000 0731 -- -- -- -- -- -- 

5-19-2000 0854 155 -- -- -- 362 120 

5-19-2000 0928 -- -- -- -- -- -- 

5-19-2000 1146 130 -- -- -- 427 100 

5-19-2000 1216 -- -- -- -- -- -- 

5-19-2000 1310 117 -- -- -- 527 100 

5-19-2000 1331 -- -- -- -- -- -- 

5-19-2000 1445 119 -- -- -- 464 120 

5-19-2000 1505 -- -- -- -- -- -- 

5-19-2000 1639 103 -- -- -- 420 110 

5-19-2000 1720 -- -- -- -- -- -- 

5-23-2000 0021 181 -- -- -- 360 110 

5-23-2000 0039 146 -- -- -- 168 85 

5-23-2000 0135 -- -- -- -- -- -- 

5-23-2000 0136 63 -- -- -- 147 50 

5-23-2000 0308 54 -- -- -- 245 37 

5-24-2000 0643 628 -- -- -- 305 260 

5-24-2000 0706 -- -- -- -- -- -- 

5-24-2000 0710 184 -- -- -- 109 100 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 136-02 (oil-grit separator outflow)—Continued

5-24-2000 0826 -- -- -- -- -- -- 

5-24-2000 0833 100 -- -- -- 129 85 

5-24-2000 0938 58 -- -- -- 148 55 

5-24-2000 1006 131 -- -- -- 144 120 

5-24-2000 1039 85 -- -- -- 156 95 

5-24-2000 2047 234 -- -- -- 518 140 

5-25-2000 0943 301 -- -- -- 429 170 

6-06-2000 11006 119 -- -- -- 400 -- 

6-06-2000 11314 100 -- -- -- 204 -- 

6-06-2000 11454 100 -- -- -- 95 -- 

6-06-2000 12005 56 -- -- -- 122 -- 

6-07-2000 10810 59 -- -- -- 262 -- 

6-07-2000 1000 53 -- -- -- 277 -- 

Monitoring location 136-03 (oil-grit separator inflow)

5-08-1999 1702 4,370 36 -- -- 944 1,700 

5-08-1999 1706 2,150 26 -- -- 925 950 

5-08-1999 1710 931 12 -- -- 831 500 

5-08-1999 1716 487 4 -- -- 766 300 

5-08-1999 1722 432 9 -- -- 699 260 

5-08-1999 1726 552 22 -- -- 642 270 

5-19-1999 2246 191 8 -- -- 2,780 65 

5-19-1999 2340 612 73 -- -- 2,650 130 

5-20-1999 0132 249 23 -- -- 1,440 245 

5-20-1999 0138 315 5 -- -- 819 210 

5-20-1999 0146 223 5 -- -- 534 210 

5-20-1999 0156 23 16 -- -- 413 160 

5-20-1999 0204 112 4 -- -- 359 130 

5-20-1999 0220 84 6 -- -- 361 90 

5-20-1999 0640 146 23 -- -- 1,040 140 

5-20-1999 0848 861 69 -- -- 1,020 200 

5-20-1999 0912 327 8 -- -- 987 230 

5-23-1999 2116 275 34 -- -- 1,350 100 

5-23-1999 2118 532 7 -- -- 668 380 

5-23-1999 2148 268 7 -- -- 672 230 

5-23-1999 2156 244 3 -- -- 495 220 

5-23-1999 2210 162 5 -- -- 342 150 

5-23-1999 2216 449 34 -- -- 254 200 

5-23-1999 2220 821 59 -- -- 215 190 

5-23-1999 2222 1,070 68 -- -- 213 200 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 136-03 (oil-grit separator inflow)—Continued

5-23-1999 2224 1,360 72 -- -- 200 190 

5-23-1999 2226 656 51 -- -- 199 180 

5-23-1999 2228 452 41 -- -- 205 150 

5-23-1999 2232 605 61 -- -- 187 130 

5-23-1999 2236 322 32 -- -- 199 130 

5-23-1999 2240 261 28 -- -- 187 110 

5-23-1999 2244 207 12 -- -- 181 120 

5-23-1999 2254 98 5 -- -- 171 75 

5-23-1999 2312 191 73 -- -- 184 50 

5-24-1999 0308 107 28 -- -- 383 65 

5-24-1999 0314 83 14 -- -- 268 55 

5-24-1999 0320 84 24 -- -- 202 50 

5-24-1999 0330 42 15 -- -- 181 38 

5-24-1999 1422 204 18 -- -- 1,330 120 

5-24-1999 1416 55 9 -- -- 308 39 

5-24-1999 1520 181 13 -- -- 850 200 

5-24-1999 1522 194 4 -- -- 854 190 

5-24-1999 1636 2,080 58 -- -- 263 400 

5-24-1999 1640 830 36 -- -- 207 290 

5-24-1999 1648 271 8 -- -- 186 310 

5-24-1999 1730 130 24 -- -- 252 110 

5-24-1999 1830 82 17 -- -- 351 85 

5-24-1999 1858 162 7 -- -- 217 120 

5-24-1999 1920 73 7 -- -- 206 90 

7-01-1999 0236 516 -- -- -- 1,440 330 

7-01-1999 0238 424 -- -- -- 1,170 260 

7-01-1999 0258 391 -- -- -- 542 170 

7-01-1999 0304 495 -- -- -- 374 190 

7-01-1999 0310 320 -- -- -- 519 170 

7-01-1999 0318 261 -- -- -- 361 190 

7-01-1999 0344 147 -- -- -- 794 100 

7-01-1999 0404 158 -- -- -- 456 140 

7-01-1999 0602 1,810 -- -- -- 331 210 

7-01-1999 0606 1,100 -- -- -- 190 130 

7-01-1999 0610 567 -- -- -- 138 130 

7-01-1999 0612 394 -- -- -- 146 130 

7-01-1999 0620 193 -- -- -- 140 110 

7-01-1999 0628 138 -- -- -- 162 95 

7-01-1999 0642 88 -- -- -- 209 65 

7-01-1999 0710 90 -- -- -- 300 60 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 136-03 (oil-grit separator inflow)—Continued

7-01-1999 1014 180 -- -- -- 612 100 

7-01-1999 1104 220 -- -- -- 385 170 

7-01-1999 1112 193 -- -- -- 283 140 

7-01-1999 1126 151 -- -- -- 255 120 

7-01-1999 1154 127 -- -- -- 300 140 

7-06-1999 1704 677 -- -- -- 899 110 

7-06-1999 1708 639 -- -- -- 523 95 

7-06-1999 1716 197 -- -- -- 519 95 

7-06-1999 1738 90 -- -- -- 764 55 

7-06-1999 1844 67 -- -- -- 812 50 

7-06-1999 2136 108 -- -- -- 575 55 

7-06-1999 2210 111 -- -- -- 831 80 

7-13-1999 0656 37 -- -- -- 1,400 60 

7-13-1999 0658 19 -- -- -- 1,450 60 

7-19-1999 1654 128 -- -- -- 399 90 

7-19-1999 1706 84 -- -- -- 256 700 

7-19-1999 1720 105 -- -- -- 211 60 

7-19-1999 1728 84 -- -- -- 195 65 

7-19-1999 1754 45 -- -- -- 276 50 

7-19-1999 1818 31 -- -- -- 387 50 

7-19-1999 1910 -- -- -- -- -- -- 

7-19-1999 1920 9 -- -- -- 401 50 

7-20-1999 1319 -- -- -- -- -- -- 

7-23-1999 0100 1,233 -- -- -- 682 300 

7-23-1999 0102 2,989 -- -- -- 445 240 

7-23-1999 0106 526 -- -- -- 242 130 

7-23-1999 0108 403 -- -- -- 255 100 

7-23-1999 0112 566 -- -- -- 199 80 

7-23-1999 0120 94 -- -- -- 182 45 

7-23-1999 0130 59 -- -- -- 188 38 

7-23-1999 0142 75 -- -- -- 178 40 

7-23-1999 0150 62 -- -- -- 159 37 

7-23-1999 0158 113 -- -- -- 141 40 

7-23-1999 0208 42 -- -- -- 139 34 

7-24-1999 2026 1,070 -- -- -- 178 120 

7-24-1999 2028 689 -- -- -- 136 110 

7-24-1999 2030 2,502 -- -- -- 134 85 

7-24-1999 2032 446 -- -- -- 131 70 

7-24-1999 2036 265 -- -- -- 129 75 

7-24-1999 2042 218 -- -- -- 132 55 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 136-03 (oil-grit separator inflow)—Continued

7-24-1999 2108 651 -- -- -- 152 80 

7-24-1999 2112 351 -- -- -- 99 55 

7-24-1999 2116 167 -- -- -- 96 50 

7-24-1999 2122 134 -- -- -- 93 50 

7-24-1999 2146 31 -- -- -- 160 23 

7-25-1999 1358 189 -- -- -- 460 80 

7-25-1999 1640 435 -- -- -- 393 75 

7-25-1999 1644 409 -- -- -- 182 80 

7-25-1999 1648 184 -- -- -- 141 55 

7-25-1999 1654 118 -- -- -- 113 60 

7-25-1999 1706 53 -- -- -- 111 40 

7-27-1999 1254 -- -- -- -- -- -- 

8-06-1999 2126 2,138 -- -- -- 1,380 100 

8-06-1999 2128 241 -- -- -- 1,340 100 

8-06-1999 2204 181 -- -- -- 1,060 90 

8-14-1999 2136 -- -- -- -- -- -- 

8-14-1999 2138 -- -- -- -- -- -- 

8-14-1999 2140 -- -- -- -- -- -- 

8-14-1999 2142 -- -- -- -- -- -- 

8-14-1999 2144 -- -- -- -- -- -- 

8-14-1999 2146 -- -- -- -- -- -- 

8-14-1999 2148 -- -- -- -- -- -- 

8-14-1999 2150 -- -- -- -- -- -- 

8-14-1999 2152 -- -- -- -- -- -- 

8-14-1999 2154 -- -- -- -- -- -- 

8-14-1999 2156 -- -- -- -- -- -- 

8-14-1999 2158 -- -- -- -- -- -- 

8-14-1999 2200 -- -- -- -- -- -- 

8-21-1999 2006 64 -- -- -- 1,070 50 

8-21-1999 2118 462 -- -- -- 523 45 

8-22-1999 0652 29 -- -- -- 375 23 

8-26-1999 1724 98 -- -- -- 853 60 

8-26-1999 1726 145 -- -- -- 798 55 

9-06-1999 1136 604 -- -- -- 645 110 

9-06-1999 1152 560 -- -- -- 279 170 

9-06-1999 1206 201 -- -- -- 272 85 

9-07-1999 0238 105 -- -- -- 252 55 

9-07-1999 0404 503 -- -- -- 237 90 

9-07-1999 0410 549 -- -- -- 158 110 

9-07-1999 0416 200 -- -- -- 148 80 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 136-03 (oil-grit separator inflow)—Continued

9-07-1999 0446 162 -- -- -- 182 40 

9-07-1999 0518 276 -- -- -- 220 37 

9-08-1999 0922 211 -- -- -- 312 120 

9-08-1999 0938 122 -- -- -- 252 110 

9-08-1999 1002 113 -- -- -- 252 120 

9-08-1999 1014 -- -- -- -- -- -- 

9-08-1999 1058 112 -- -- -- 309 90 

9-10-1999 0752 215 -- -- -- 271 160 

9-10-1999 0814 284 -- -- -- 204 120 

9-10-1999 0822 2,170 -- -- -- 124 190 

9-10-1999 0826 540 -- -- -- 116 200 

9-10-1999 0838 126 -- -- -- 105 85 

9-10-1999 0906 68 -- -- -- 135 65 

9-10-1999 0954 508 -- -- -- 149 160 

9-10-1999 1004 137 -- -- -- 128 95 

9-10-1999 1148 49 -- -- -- 180 55 

9-10-1999 1442 214 -- -- -- 231 120 

9-10-1999 1450 165 -- -- -- 154 120 

9-10-1999 1500 135 -- -- -- 120 95 

9-10-1999 1508 386 -- -- -- 77 85 

9-10-1999 1520 82 -- -- -- 78 50 

9-15-1999 1850 47 -- -- -- 459 45 

9-15-1999 1936 176 -- -- -- 348 150 

9-15-1999 2004 116 -- -- -- 219 100 

9-15-1999 2026 92 -- -- -- 150 95 

9-15-1999 2052 62 -- -- -- 137 70 

9-15-1999 2112 53 -- -- -- 118 60 

9-15-1999 2136 44 -- -- -- 112 50 

9-15-1999 2220 32 -- -- -- 139 40 

9-15-1999 2320 46 -- -- -- 145 55 

9-15-1999 2346 41 -- -- -- 104 50 

9-16-1999 0006 50 -- -- -- 79 55 

9-16-1999 0020 53 -- -- -- 65 45 

9-16-1999 0038 31 -- -- -- 59 34 

9-16-1999 0052 24 -- -- -- 57 27 

9-16-1999 0948 318 -- -- -- 51 80 

9-16-1999 1016 83 -- -- -- 49 60 

9-16-1999 1228 56 -- -- -- 120 70 

9-16-1999 1412 140 -- -- -- 92 75 

9-16-1999 1520 457 -- -- -- 81 90 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 136-03 (oil-grit separator inflow)—Continued

9-16-1999 1536 96 -- -- -- 76 40 

9-16-1999 1604 196 -- -- -- 60 29 

9-16-1999 1634 29 -- -- -- 72 19 

9-16-1999 1654 296 -- -- -- 34 50 

9-16-1999 1822 43 -- -- -- 82 25 

9-22-1999 2334 189 -- -- -- 507 110 

9-22-1999 2336 145 -- -- -- 542 110 

10-06-1999 1426 -- -- -- -- -- -- 

10-18-1999 0712 52 -- -- -- 85 36 

10-18-1999 0714 29 -- -- -- 81 31 

10-20-1999 0820 52 -- -- -- 243 120 

10-20-1999 0854 218 -- -- -- 169 170 

10-20-1999 0908 141 -- -- -- 138 160 

10-20-1999 1204 192 -- -- -- 156 140 

10-20-1999 1216 197 -- -- -- 86 130 

10-20-1999 1234 120 -- -- -- 66 90 

10-23-1999 0208 248 -- -- -- 177 90 

10-23-1999 0240 208 -- -- -- 176 55 

10-23-1999 0302 67 -- -- -- 167 45 

10-23-1999 0330 56 -- -- -- 113 37 

10-23-1999 0346 77 -- -- -- 78 38 

10-23-1999 0404 59 -- -- -- 65 36 

10-23-1999 0418 53 -- -- -- 61 27 

10-23-1999 0444 49 -- -- -- 62 27 

10-26-1999 1530 -- -- -- -- -- -- 

11-02-1999 2340 377 54 -- -- 320 230 

11-02-1999 2358 352 67 -- -- 264 140 

11-03-1999 0020 186 25 -- -- 216 110 

11-03-1999 0042 227 65 -- -- 200 90 

11-03-1999 0106 203 56 -- -- 166 75 

11-03-1999 0122 84 7 -- -- 122 70 

11-03-1999 0136 77 16 -- -- 95 60 

11-03-1999 0146 53 11 -- -- 86 50 

11-03-1999 0158 51 16 -- -- 80 38 

11-03-1999 0208 40 14 -- -- 76 33 

11-03-1999 0218 32 16 -- -- 77 36 

11-03-1999 0234 162 73 -- -- 77 31 

11-03-1999 0244 36 16 -- -- 75 27 

11-03-1999 0256 435 76 -- -- 423 120 

12-20-1999 2307 128 -- -- -- 94 70 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 136-03 (oil-grit separator inflow)—Continued

12-20-1999 2330 173 -- -- -- 451 100 

12-20-1999 2344 288 -- -- -- 448 180 

12-21-1999 0019 230 -- -- -- 360 170 

12-21-1999 0047 200 -- -- -- 315 160 

12-21-1999 0058 248 -- -- -- 285 160 

12-21-1999 0118 182 -- -- -- 214 150 

12-21-1999 0300 150 -- -- -- 171 120 

12-21-1999 0332 -- -- -- -- 199 100 

1-10-2000 1956 63 -- -- -- 729 28 

1-10-2000 2012 56 -- -- -- 818 29 

1-10-2000 2032 58 -- -- -- 890 26 

1-10-2000 2057 51 -- -- -- 1,020 33 

1-10-2000 2158 85 -- -- -- 1,220 31 

1-13-2000 0922 178 -- -- -- 4,130 120 

1-13-2000 0951 200 -- -- -- 7,830 150 

1-13-2000 1007 301 -- -- -- 6,580 220 

1-16-2000 1002 252 -- -- -- 12,300 270 

1-16-2000 1039 187 -- -- -- 13,300 230 

1-20-2000 1930 -- -- -- -- -- -- 

1-27-2000 1530 -- -- -- -- -- -- 

1-31-2000 0348 158 -- -- -- 79,100 110 

1-31-2000 0406 118 -- -- -- 93,100 130 

1-31-2000 0428 332 -- -- -- 86,200 250 

1-31-2000 0429 -- -- -- -- -- -- 

1-31-2000 0445 1,212 -- -- -- 37,100 1,100 

1-31-2000 0521 397 -- -- -- 16,900 450 

1-31-2000 0524 -- -- -- -- -- -- 

1-31-2000 0543 441 -- -- -- 10,600 450 

1-31-2000 0558 -- -- -- -- -- -- 

1-31-2000 0618 374 -- -- -- 7,840 400 

2-14-2000 0753 247 -- -- -- 2,510 220 

2-14-2000 0813 324 -- -- -- 2,710 270 

2-14-2000 0838 274 -- -- -- 3,380 310 

2-14-2000 0857 -- -- -- -- -- -- 

2-14-2000 0924 526 28 -- -- 2,950 360 

2-14-2000 0932 2,650 70 -- -- 2,050 500 

2-14-2000 0935 1,690 30 -- -- 2,270 750 

2-14-2000 0938 1,127 -- -- -- 2,050 750 

2-14-2000 0948 746 -- -- -- 1,700 550 

2-14-2000 1018 544 -- -- -- 1,640 310 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 136-03 (oil-grit separator inflow)—Continued

2-14-2000 1029 327 -- -- -- 1,710 280 

2-14-2000 1104 415 -- -- -- 1,810 370 

2-14-2000 1122 412 -- -- -- 1,750 330 

2-14-2000 1140 559 -- -- -- 1,780 380 

2-14-2000 1152 809 -- -- -- 1,490 500 

2-14-2000 1156 780 -- -- -- 1,430 500 

2-14-2000 1201 674 -- -- -- 1,400 500 

2-14-2000 1212 497 -- -- -- 1,540 400 

2-18-2000 1455 -- -- -- -- -- -- 

2-18-2000 2138 -- -- -- -- -- -- 

2-18-2000 2142 -- -- -- -- -- -- 

2-18-2000 2145 -- -- -- -- -- -- 

2-18-2000 2148 -- -- -- -- -- -- 

2-18-2000 2218 -- -- -- -- -- -- 

2-25-2000 1440 520 -- -- -- 28,200 260 

2-25-2000 1507 1,280 -- -- -- 13,000 3,100 

2-25-2000 1524 1,740 -- -- -- 9,450 4,100 

2-25-2000 1544 1,150 -- -- -- 6,420 2,400 

2-25-2000 1604 817 -- -- -- 4,950 1,300 

2-25-2000 1619 629 -- -- -- 4,200 830 

2-25-2000 1639 817 -- -- -- 3,570 680 

2-25-2000 1659 539 -- -- -- 3,090 540 

2-25-2000 1713 495 -- -- -- 2,800 410 

2-25-2000 1727 382 -- -- -- 2,640 380 

2-25-2000 1744 300 -- -- -- 2,760 340 

2-25-2000 1927 198 -- -- -- 3,250 250 

2-25-2000 1948 360 -- -- -- 2,580 390 

2-25-2000 2008 300 -- -- -- 2,690 340 

2-25-2000 2100 210 -- -- -- 2,540 260 

2-25-2000 2122 -- -- -- -- -- -- 

2-25-2000 2201 190 -- -- -- 2,400 210 

2-25-2000 2219 144 -- -- -- 2,250 180 

2-25-2000 2243 145 -- -- -- 2,250 180 

2-26-2000 0711 223 -- -- -- 2,700 220 

2-26-2000 0728 191 -- -- -- 2,120 230 

2-27-2000 0810 1,260 -- -- -- 4,960 1,100 

2-27-2000 0827 1,630 -- -- -- 5,470 980 

2-27-2000 0848 703 -- -- -- 4,190 880 

3-28-2000 0439 153 4 2.13 1.85 4,330 150 

3-28-2000 0449 1,980 45 3.35 41.15 4,630 760 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 136-03 (oil-grit separator inflow)—Continued

3-28-2000 0457 1,480 37 1.97 35.09 17,800 890 

3-28-2000 0505 1,030 30 1.60 28.35 11,700 730 

3-28-2000 0510 669 6 3.79 2.03 8,250 600 

3-28-2000 0515 1,020 35 5.63 29.09 6,380 630 

3-28-2000 0525 886 34 6.33 27.30 5,050 500 

3-28-2000 0539 1,800 75 3.82 70.79 3,910 360 

3-28-2000 0551 600 38 12.86 25.10 3,690 300 

3-28-2000 0605 566 38 3.07 35.38 2,940 320 

3-28-2000 0615 647 39 8.44 30.37 2,490 310 

3-28-2000 0627 -- -- -- -- -- -- 

3-28-2000 0641 569 26 4.57 21.89 1,910 320 

3-28-2000 0654 497 41 1.34 40.01 1,690 250 

3-28-2000 0659 6,920 88 12.81 75.41 1,280 430 

3-28-2000 0705 6,560 75 4.98 70.01 1,160 530 

3-28-2000 0722 2,890 80 5.10 75.35 1,220 350 

3-28-2000 0738 -- -- -- -- -- -- 

3-28-2000 0754 942 62 11.28 50.84 816 230 

3-28-2000 0817 490 49 5.53 43.67 807 180 

3-28-2000 0921 320 43 5.45 37.82 783 140 

3-28-2000 1106 208 46 3.07 43.02 1,830 120 

3-28-2000 1453 147 20 1.96 17.74 3,240 180 

3-28-2000 2136 -- -- -- -- -- -- 

4-04-2000 0338 -- -- -- -- -- -- 

4-04-2000 0402 -- -- -- -- -- -- 

4-04-2000 1453 -- -- -- -- -- -- 

4-04-2000 1525 -- -- -- -- -- -- 

4-04-2000 1600 -- -- -- -- -- -- 

4-04-2000 1633 -- -- -- -- -- -- 

4-04-2000 1808 -- -- -- -- -- -- 

4-04-2000 2153 -- -- -- -- -- -- 

4-04-2000 0225 -- -- -- -- -- -- 

4-08-2000 2317 7,110 -- -- -- 3,660 230 

4-08-2000 2341 951 -- -- -- 1,970 500 

4-09-2000 0035 311 -- -- -- 1,860 310 

4-09-2000 0148 306 -- -- -- 1,670 270 

4-09-2000 0150 -- -- -- -- -- -- 

4-09-2000 0219 159 -- -- -- 993 160 

4-09-2000 0222 -- -- -- -- -- -- 

4-09-2000 0304 577 -- -- -- 886 140 

4-09-2000 0341 -- -- -- -- -- -- 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 136-03 (oil-grit separator inflow)—Continued

4-09-2000 0426 315 -- -- -- 520 80 

4-09-2000 0452 -- -- -- -- -- -- 

4-09-2000 0502 750 -- -- -- 437 190 

4-09-2000 0518 -- -- -- -- -- -- 

4-09-2000 0533 507 -- -- -- 359 85 

4-09-2000 0600 -- -- -- -- -- -- 

4-09-2000 0609 2,190 -- -- -- 338 100 

4-09-2000 0632 -- -- -- -- -- -- 

4-09-2000 0658 112 -- -- -- 377 65 

4-09-2000 0725 -- -- -- -- -- -- 

4-09-2000 0729 1,890 -- -- -- 234 200 

4-09-2000 0735 -- -- -- -- -- -- 

4-09-2000 0741 292 -- -- -- 224 100 

4-09-2000 0757 -- -- -- -- -- -- 

4-09-2000 0821 291 -- -- -- 257 55 

4-16-2000 0649 284 -- -- -- 921 120 

4-16-2000 0754 -- -- -- -- -- -- 

4-18-2000 1828 602 -- -- -- 1,610 95 

4-18-2000 1901 1,940 -- -- -- 1,040 230 

4-18-2000 1939 2,670 -- -- -- 778 190 

4-18-2000 2011 421 -- -- -- 578 160 

4-18-2000 2012 -- -- -- -- -- -- 

4-18-2000 2041 1,380 -- -- -- 477 140 

4-18-2000 2042 -- -- -- -- -- -- 

4-18-2000 2105 372 -- -- -- 374 110 

4-18-2000 2140 -- -- -- -- -- -- 

4-18-2000 2207 230 -- -- -- 331 90 

4-18-2000 2239 -- -- -- -- -- -- 

4-18-2000 2342 188 -- -- -- 349 65 

4-19-2000 0013 -- -- -- -- -- -- 

4-19-2000 0142 63 -- -- -- 343 45 

4-19-2000 0432 -- -- -- -- -- -- 

4-19-2000 0601 298 -- -- -- 482 120 

4-19-2000 0730 -- -- -- -- -- -- 

4-19-2000 0814 314 -- -- -- 415 140 

4-21-2000 1252 139 -- -- -- 1,230 160 

4-21-2000 1543 317 -- -- -- 1,100 400 

4-21-2000 1545 -- -- -- -- -- -- 

4-21-2000 1717 302 -- -- -- 715 230 

4-21-2000 1719 -- -- -- -- -- -- 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 136-03 (oil-grit separator inflow)—Continued

4-21-2000 1833 310 -- -- -- 541 170 

4-21-2000 1835 -- -- -- -- -- -- 

4-21-2000 1938 172 -- -- -- 401 160 

4-21-2000 1939 -- -- -- -- -- -- 

4-21-2000 1953 1,270 -- -- -- 264 230 

4-21-2000 2002 -- -- -- -- -- -- 

4-21-2000 2024 391 -- -- -- 189 130 

4-21-2000 2117 -- -- -- -- -- -- 

4-21-2000 2124 630 -- -- -- 186 150 

4-21-2000 2135 -- -- -- -- -- -- 

4-21-2000 2143 283 -- -- -- 142 110 

4-21-2000 2217 -- -- -- -- -- -- 

4-21-2000 2234 909 -- -- -- 135 95 

4-21-2000 2240 -- -- -- -- -- -- 

4-21-2000 2247 582 -- -- -- 108 95 

4-21-2000 2259 -- -- -- -- -- -- 

4-21-2000 2313 337 -- -- -- 108 50 

4-21-2000 2347 -- -- -- -- -- -- 

4-22-2000 0007 108 -- -- -- 111 40 

4-22-2000 0021 -- -- -- -- -- -- 

4-22-2000 0031 192 -- -- -- 92 55 

4-22-2000 0042 -- -- -- -- -- -- 

4-22-2000 0052 184 -- -- -- 89 70 

4-22-2000 0101 -- -- -- -- -- -- 

4-22-2000 0109 981 -- -- -- 86 80 

4-22-2000 0115 -- -- -- -- -- -- 

4-22-2000 0132 426 -- -- -- 108 70 

4-22-2000 0140 -- -- -- -- -- -- 

4-22-2000 0157 1,995 -- -- -- 91 95 

4-22-2000 0203 -- -- -- -- -- -- 

4-22-2000 0226 372 -- -- -- 85 60 

4-22-2000 0233 -- -- -- -- -- -- 

4-22-2000 0251 308 -- -- -- 83 55 

4-22-2000 0259 -- -- -- -- -- -- 

4-22-2000 0319 137 -- -- -- 102 50 

4-22-2000 0355 -- -- -- -- -- -- 

4-22-2000 0603 549 91 -- -- 151 50 

4-22-2000 0738 -- -- -- -- -- -- 

4-22-2000 1240 244 70 -- -- 181 65 

4-22-2000 1241 -- -- -- -- -- -- 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 136-03 (oil-grit separator inflow)—Continued

4-22-2000 1647 352 91 -- -- 191 40 

4-26-2000 0316 276 -- -- -- 750 40 

4-26-2000 0416 564 -- -- -- 1,190 160 

4-26-2000 0457 432 -- -- -- 892 190 

4-26-2000 0525 439 -- -- -- 537 190 

4-26-2000 0554 307 -- -- -- 440 180 

4-26-2000 0646 294 -- -- -- 462 140 

4-26-2000 0814 -- -- -- -- -- -- 

4-26-2000 0932 138 -- -- -- 511 130 

4-26-2000 1919 111 -- -- -- 359 130 

5-02-2000 0559 -- -- -- -- -- -- 

5-02-2000 0719 -- -- -- -- -- -- 

5-02-2000 0806 595 -- -- -- 374 320 

5-02-2000 0842 770 -- -- -- 721 230 

5-08-2000 1711 2,890 -- -- -- 1,630 900 

5-08-2000 1718 1,920 -- -- -- 963 500 

5-08-2000 1726 610 -- -- -- 808 290 

5-10-2000 1328 -- -- -- -- -- -- 

5-10-2000 1502 166 -- -- -- 675 120 

5-10-2000 2027 864 -- -- -- 0 

5-10-2000 2034 -- -- -- -- 291 310 

5-10-2000 2202 -- -- -- -- -- -- 

5-10-2000 2229 1,070 -- -- -- 163 200 

5-10-2000 2258 -- -- -- -- -- -- 

5-10-2000 2325 125 -- -- -- 145 40 

5-13-2000 2257 550 -- -- -- 244 110 

5-18-2000 1847 269 -- -- -- 987 75 

5-18-2000 1916 225 -- -- -- 520 140 

5-18-2000 1954 126 -- -- -- 488 21 

5-19-2000 0646 276 -- -- -- 845 130 

5-19-2000 0717 -- -- -- -- -- -- 

5-19-2000 0731 218 -- -- -- 339 120 

5-19-2000 0854 -- -- -- -- -- -- 

5-19-2000 0928 148 -- -- -- 482 95 

5-19-2000 1146 -- -- -- -- -- -- 

5-19-2000 1216 140 -- -- -- 630 120 

5-19-2000 1310 -- -- -- -- -- -- 

5-19-2000 1331 129 -- -- -- 444 130 

5-19-2000 1445 -- -- -- -- -- -- 

5-19-2000 1505 121 -- -- -- 389 120 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 136-03 (oil-grit separator inflow)—Continued

5-19-2000 1639 -- -- -- -- -- -- 

5-19-2000 1720 129 -- -- -- 398 75 

5-23-2000 0021 185 -- -- -- 229 90 

5-23-2000 0039 126 -- -- -- 141 67 

5-23-2000 0135 50 -- -- -- 182 38 

5-23-2000 0136 -- -- -- -- -- -- 

5-23-2000 0308 -- -- -- -- -- -- 

5-24-2000 0643 1,409 -- -- -- 214 270 

5-24-2000 0706 243 -- -- -- 104 85 

5-24-2000 0710 -- -- -- -- -- -- 

5-24-2000 0826 118 -- -- -- 120 85 

5-24-2000 0833 -- -- -- -- -- -- 

5-24-2000 0938 60 -- -- -- 195 45 

5-24-2000 1006 134 -- -- -- 349 75 

5-24-2000 1039 98 -- -- -- 145 100 

5-24-2000 2047 477 -- -- -- 404 240 

5-25-2000 0943 -- -- -- -- -- -- 

6-06-2000 11006 872 -- -- -- 503 -- 

6-06-2000 11314 114 -- -- -- 236 -- 

6-06-2000 11454 132 -- -- -- 97 -- 

6-06-2000 12005 144 -- -- -- 114 -- 

6-07-2000 10810 94 -- -- -- 262 -- 

6-07-2000 1000 -- -- -- -- -- -- 

Monitoring location 136-04 (catch basin outflow)

5-20-1999 0138 318 16 -- -- 635 290 

5-20-1999 0140 244 3 -- -- 626 260 

5-20-1999 0144 237 4 -- -- 593 270 

5-20-1999 0146 224 1 -- -- 593 270 

5-20-1999 0148 230 1 -- -- 539 250 

5-20-1999 0150 214 2 -- -- 530 230 

5-20-1999 0858 229 12 -- -- 470 300 

5-24-1999 1520 166 4 -- -- 476 200 

5-24-1999 1730 625 0 -- -- -- -- 

5-24-1999 1858 179 4 -- -- -- -- 

5-24-1999 1920 113 4 -- -- -- -- 

7-01-1999 0258 344 -- -- -- 479 230 

7-01-1999 0304 384 -- -- -- 365 200 

7-01-1999 0310 263 -- -- -- 261 140 

7-01-1999 0354 189 -- -- -- 276 130 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 136-04 (catch basin outflow)—Continued

7-01-1999 0408 159 -- -- -- 255 140 

7-01-1999 0602 498 -- -- -- 198 180 

7-01-1999 0606 639 -- -- -- 139 200 

7-01-1999 0608 -- -- -- -- 100 210 

7-01-1999 0610 1,140 -- -- -- 77 350 

7-01-1999 0614 897 -- -- -- 73 330 

7-01-1999 0616 505 -- -- -- 87 260 

7-01-1999 0626 298 -- -- -- 72 180 

7-01-1999 0650 188 -- -- -- 126 160 

7-01-1999 1056 286 -- -- -- 195 230 

7-01-1999 1104 301 -- -- -- 183 250 

7-01-1999 1114 279 -- -- -- 163 240 

7-06-1999 1704 375 -- -- -- 501 140 

7-06-1999 1708 412 -- -- -- 318 130 

7-06-1999 1710 310 -- -- -- 259 140 

7-06-1999 1712 237 -- -- -- 254 120 

7-06-1999 1724 135 -- -- -- 247 60 

7-06-1999 2130 179 -- -- -- 362 130 

7-06-1999 2140 144 -- -- -- 332 120 

7-19-1999 1646 38 -- -- -- 386 140 

7-19-1999 1652 111 -- -- -- 285 130 

7-19-1999 1654 -- -- -- -- -- #VALUE! 

7-19-1999 1700 72 -- -- -- 225 100 

7-19-1999 1708 66 -- -- -- 189 120 

7-19-1999 1720 46 -- -- -- 165 100 

7-19-1999 1724 149 -- -- -- 138 75 

7-19-1999 1732 97 -- -- -- 112 70 

7-19-1999 1750 28 -- -- -- 109 55 

7-23-1999 0100 209 -- -- -- 182 130 

7-23-1999 0104 192 -- -- -- 118 95 

7-23-1999 0108 126 -- -- -- 86 65 

7-23-1999 0110 125 -- -- -- 86 50 

7-23-1999 0112 110 -- -- -- 87 65 

7-23-1999 0116 95 -- -- -- 92 60 

7-23-1999 0124 132 -- -- -- 124 50 

7-23-1999 0136 62 -- -- -- 120 45 

7-23-1999 0146 48 -- -- -- 93 32 

7-23-1999 0156 59 -- -- -- 68 39 

7-23-1999 0204 47 -- -- -- 78 34 

7-24-1999 2026 557 -- -- -- 85 130 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 136-04 (catch basin outflow)—Continued

7-24-1999 2030 453 -- -- -- 84 150 

7-24-1999 2032 163 -- -- -- 82 55 

7-24-1999 2034 119 -- -- -- 92 45 

7-24-1999 2036 50 -- -- -- 92 33 

7-24-1999 2040 35 -- -- -- 117 34 

7-24-1999 2050 -- -- -- -- -- -- 

7-24-1999 2108 456 -- -- -- 91 140 

7-24-1999 2112 162 -- -- -- 59 50 

7-24-1999 2114 218 -- -- -- 58 50 

7-24-1999 2116 64 -- -- -- 63 31 

7-24-1999 2120 84 -- -- -- 71 26 

7-25-1999 1642 159 -- -- -- 94 50 

7-25-1999 1646 119 -- -- -- 78 39 

7-25-1999 1648 -- -- -- -- 70 40 

7-25-1999 1656 -- -- -- -- -- -- 

8-06-1999 2144 168 -- -- -- 638 80 

8-14-1999 2136 222 -- -- -- 429 90 

8-14-1999 2140 171 -- -- -- 338 110 

8-21-1999 2058 36 -- -- -- 328 34 

8-21-1999 2100 26 -- -- -- 326 27 

8-21-1999 2132 30 -- -- -- 297 27 

8-21-1999 2232 35 -- -- -- 281 24 

8-21-1999 2336 34 -- -- -- 270 40 

8-22-1999 0116 33 -- -- -- 271 27 

8-22-1999 0212 102 -- -- -- 294 46 

8-22-1999 0606 29 -- -- -- 256 29 

8-22-1999 0640 32 -- -- -- 241 28 

8-22-1999 0706 30 -- -- -- 223 28 

8-22-1999 0746 28 -- -- -- 205 24 

8-26-1999 1724 102 -- -- -- 443 65 

8-26-1999 1838 90 -- -- -- 403 75 

9-06-1999 1124 240 -- -- -- 298 100 

9-06-1999 1136 140 -- -- -- 223 120 

9-06-1999 1150 85 -- -- -- 171 100 

9-06-1999 1154 101 -- -- -- 196 85 

9-06-1999 1204 95 -- -- -- 177 12 

9-07-1999 0232 71 -- -- -- 154 85 

9-07-1999 0236 33 -- -- -- 167 40 

9-07-1999 0246 123 -- -- -- 122 110 

9-07-1999 0356 127 -- -- -- 97 100 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 136-04 (catch basin outflow)—Continued

9-07-1999 0406 112 -- -- -- 84 100 

9-07-1999 0410 82 -- -- -- 87 85 

9-07-1999 0416 90 -- -- -- 101 110 

9-07-1999 0440 67 -- -- -- 113 110 

9-07-1999 0456 136 -- -- -- 817 160 

9-08-1999 0914 151 -- -- -- 208 170 

9-08-1999 0922 171 -- -- -- 189 180 

9-08-1999 0932 173 -- -- -- 185 200 

9-08-1999 0950 159 -- -- -- 183 200 

9-08-1999 1008 145 -- -- -- 192 190 

9-08-1999 1058 153 -- -- -- 207 220 

9-10-1999 0742 278 -- -- -- 248 260 

9-10-1999 0754 280 -- -- -- 223 260 

9-10-1999 0810 260 -- -- -- 200 250 

9-10-1999 0820 278 -- -- -- 168 240 

9-10-1999 0824 327 -- -- -- 107 190 

9-10-1999 0828 238 -- -- -- 82 170 

9-10-1999 0836 185 -- -- -- 75 140 

9-10-1999 0850 160 -- -- -- 78 140 

9-10-1999 0904 155 -- -- -- 84 140 

9-10-1999 0930 121 -- -- -- 92 130 

9-10-1999 0956 231 -- -- -- 95 170 

9-10-1999 1004 145 -- -- -- 89 160 

9-10-1999 1042 121 -- -- -- 101 140 

9-10-1999 1222 76 -- -- -- 122 110 

9-10-1999 1300 125 -- -- -- 122 150 

9-10-1999 1426 80 -- -- -- 141 120 

9-10-1999 1444 172 -- -- -- 136 190 

9-10-1999 1452 177 -- -- -- 113 170 

9-10-1999 1500 155 -- -- -- 101 150 

9-10-1999 1506 169 -- -- -- 86 140 

9-10-1999 1510 167 -- -- -- 68 120 

9-10-1999 1514 136 -- -- -- 61 110 

9-10-1999 1522 115 -- -- -- 59 94 

9-15-1999 1846 -- -- -- -- -- -- 

9-15-1999 1908 114 -- -- -- 243 120 

9-15-1999 1928 112 -- -- -- 233 140 

9-15-1999 1946 106 -- -- -- 199 130 

9-15-1999 2000 106 -- -- -- 173 120 

9-15-1999 2010 106 -- -- -- 147 120 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 136-04 (catch basin outflow)—Continued

9-15-1999 2022 95 -- -- -- 122 110 

9-15-1999 2038 78 -- -- -- 105 90 

9-15-1999 2052 78 -- -- -- 96 95 

9-15-1999 2104 78 -- -- -- 86 95 

9-15-1999 2116 72 -- -- -- 79 90 

9-15-1999 2130 66 -- -- -- 74 80 

9-15-1999 2156 56 -- -- -- 73 75 

9-15-1999 2256 58 -- -- -- 85 75 

9-15-1999 2320 63 -- -- -- 88 85 

9-15-1999 2332 66 -- -- -- 79 90 

9-15-1999 2348 60 -- -- -- 70 82 

9-16-1999 0000 65 -- -- -- 63 80 

9-16-1999 0010 58 -- -- -- 53 70 

9-16-1999 0020 66 -- -- -- 47 75 

9-16-1999 0028 56 -- -- -- 41 65 

9-16-1999 0042 55 -- -- -- 38 55 

9-16-1999 0054 40 -- -- -- 36 45 

9-16-1999 0142 30 -- -- -- 40 40 

9-22-1999 2336 -- -- -- -- -- -- 

9-22-1999 2354 157 -- -- -- -- -- 

9-23-1999 0204 163 -- -- -- -- -- 

10-18-1999 0712 70 -- -- -- 55 65 

10-20-1999 0756 117 -- -- -- 119 120 

10-20-1999 0818 135 -- -- -- 142 200 

10-20-1999 0842 189 -- -- -- 145 230 

10-20-1999 0856 233 -- -- -- 132 250 

10-20-1999 0912 227 -- -- -- 117 240 

10-20-1999 0944 212 -- -- -- 112 230 

10-20-1999 1100 -- -- -- -- -- -- 

10-20-1999 1204 244 -- -- -- 99 230 

10-20-1999 1210 293 -- -- -- 69 200 

10-20-1999 1218 190 -- -- -- 51 140 

10-20-1999 1230 151 -- -- -- 46 110 

10-20-1999 1244 117 -- -- -- 44 100 

10-23-1999 0202 -- -- -- -- -- -- 

10-23-1999 0228 121 -- -- -- 142 110 

10-23-1999 0256 121 -- -- -- 132 110 

10-23-1999 0318 97 -- -- -- 108 95 

10-23-1999 0334 107 -- -- -- 80 90 

10-23-1999 0346 99 -- -- -- 57 80 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 136-04 (catch basin outflow)—Continued

10-23-1999 0402 98 -- -- -- 48 75 

10-23-1999 0414 95 -- -- -- 42 65 

10-23-1999 0446 54 -- -- -- 41 55 

10-23-1999 0640 51 -- -- -- 53 60 

10-23-1999 0908 -- -- -- -- -- -- 

11-02-1999 2354 164 -- -- -- 205 150 

11-03-1999 0038 166 -- -- -- 150 170 

11-03-1999 0118 142 -- -- -- 109 150 

11-03-1999 0138 131 -- -- -- 70 110 

11-03-1999 0152 104 -- -- -- 47 80 

11-03-1999 0210 80 -- -- -- 38 55 

11-03-1999 0234 96 -- -- -- 39 60 

11-03-1999 0254 70 -- -- -- 40 50 

12-20-1999 2325 244 -- -- -- 68 240 

2-14-2000 0753 485 -- -- -- 1,530 340 

2-14-2000 0813 535 -- -- -- 1,850 600 

2-14-2000 0838 779 -- -- -- 1,890 1,100 

2-14-2000 0924 816 -- -- -- 1,940 1,400 

2-14-2000 0925 851 -- -- -- 2,120 1,300 

2-14-2000 0933 1,590 -- -- -- 2,420 800 

2-14-2000 0938 938 -- -- -- 1,980 700 

2-14-2000 1016 575 -- -- -- 1,690 550 

2-14-2000 1057 424 -- -- -- 1,680 450 

2-14-2000 1125 410 -- -- -- 1,570 400 

2-14-2000 1138 571 -- -- -- 1,510 500 

2-14-2000 1150 637 -- -- -- 1,460 550 

2-14-2000 1155 918 -- -- -- 1,590 550 

2-14-2000 1159 908 -- -- -- 1,730 600 

2-14-2000 1209 720 -- -- -- 1,520 600 

2-28-2000 0753 490 -- -- -- 3,060 500 

2-28-2000 0804 725 -- -- -- 2,880 800 

2-28-2000 0814 886 -- -- -- 2,530 1,200 

2-28-2000 0823 906 -- -- -- 1,990 1,100 

2-28-2000 0831 1,010 -- -- -- 1,800 1,100 

2-28-2000 0843 866 -- -- -- 1,590 1,000 

3-28-2000 0451 625 2 1 1 11,900 700 

3-28-2000 0459 720 2 1 1 9,850 850 

3-28-2000 0506 753 5 4 2 7,830 800 

3-28-2000 0511 761 12 7 5 6,280 700 

3-28-2000 0517 575 7 4 2 4,890 550 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 136-04 (catch basin outflow)—Continued

3-28-2000 0541 577 2 1 0 3,530 550 

3-28-2000 0559 608 3 2 1 2,970 550 

3-28-2000 0618 920 3 2 1 2,340 750 

3-28-2000 0630 696 6 3 3 2,000 550 

3-28-2000 0643 490 8 7 1 1,700 340 

3-28-2000 0700 7,030 88 18 70 1,340 500 

3-28-2000 0708 783 43 19 24 1,160 300 

3-28-2000 0721 792 55 12 43 1,170 230 

3-28-2000 0754 608 46 10 35 943 220 

3-28-2000 0804 468 21 5 16 1,060 230 

3-28-2000 0816 315 19 7 13 1,080 160 

4-04-2000 0342 598 -- -- -- 1,530 500 

4-08-2000 2319 1,110 -- -- -- 2,310 130 

4-08-2000 2323 801 -- -- -- 2,590 450 

4-08-2000 2329 567 -- -- -- 1,360 500 

4-09-2000 0149 321 -- -- -- 1,060 300 

4-09-2000 0156 283 -- -- -- 921 240 

4-09-2000 0214 173 -- -- -- 717 200 

4-09-2000 0304 193 -- -- -- 659 200 

4-09-2000 0323 133 -- -- -- 549 130 

4-09-2000 0428 90 -- -- -- 387 90 

4-09-2000 0450 561 -- -- -- 389 170 

4-09-2000 0508 269 -- -- -- 282 160 

4-09-2000 0517 209 -- -- -- 212 140 

4-09-2000 0529 146 -- -- -- 172 110 

4-09-2000 0549 120 -- -- -- 171 95 

4-09-2000 0611 146 -- -- -- 151 110 

4-09-2000 0625 136 -- -- -- 148 95 

4-09-2000 0721 344 -- -- -- 189 130 

4-09-2000 0743 185 -- -- -- 89 80 

4-18-2000 1849 104 -- -- -- 2,070 520 

4-18-2000 1900 124 -- -- -- 1,600 590 

4-21-2000 1939 146 -- -- -- 460 190 

4-21-2000 1949 154 -- -- -- 361 180 

4-21-2000 1956 1,250 -- -- -- 271 240 

4-21-2000 2002 295 -- -- -- 192 180 

4-21-2000 2017 189 -- -- -- 155 160 

4-21-2000 2113 127 -- -- -- 152 130 

4-21-2000 2126 270 -- -- -- 133 140 

4-21-2000 2147 173 -- -- -- 89 100 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 136-04 (catch basin outflow)—Continued

4-21-2000 2236 567 -- -- -- 99 130 

4-21-2000 2253 142 -- -- -- 66 80 

4-21-2000 2311 91 -- -- -- 64 65 

4-21-2000 2341 54 -- -- -- 70 55 

4-22-2000 0002 64 -- -- -- 78 60 

4-22-2000 0019 96 -- -- -- 73 55 

4-22-2000 0033 98 -- -- -- 64 55 

4-22-2000 0056 87 -- -- -- 59 60 

4-22-2000 0114 359 -- -- -- 50 55 

4-22-2000 0129 432 -- -- -- 43 55 

4-22-2000 0227 1,470 -- -- -- 60 45 

4-22-2000 0327 115 -- -- -- 76 55 

4-23-2000 1648 88 -- -- -- 184 55 

5-02-2000 0642 434 -- -- -- 708 400 

5-02-2000 0806 536 -- -- -- 590 600 

5-02-2000 0817 508 -- -- -- 532 550 

5-02-2000 0830 443 -- -- -- 512 550 

5-08-2000 1712 872 -- -- -- 822 400 

5-08-2000 1714 1,140 -- -- -- 775 450 

5-08-2000 1717 883 -- -- -- 644 410 

5-08-2000 1720 684 -- -- -- 593 360 

5-08-2000 1724 471 -- -- -- 567 320 

5-08-2000 1736 310 -- -- -- 552 210 

5-10-2000 1330 263 -- -- -- 478 210 

5-10-2000 2029 884 -- -- -- 211 370 

5-10-2000 2031 876 -- -- -- 143 400 

5-10-2000 2033 762 -- -- -- 120 380 

5-10-2000 2037 503 -- -- -- 106 310 

5-10-2000 2055 302 -- -- -- 107 220 

5-10-2000 2117 234 -- -- -- 119 200 

5-10-2000 2202 185 -- -- -- 134 190 

5-10-2000 2221 185 -- -- -- 143 210 

5-10-2000 2229 232 -- -- -- 100 170 

5-10-2000 2237 140 -- -- -- 56 100 

5-11-2000 0008 75 -- -- -- 76 75 

5-13-2000 2249 490 -- -- -- 212 150 

5-13-2000 2253 417 -- -- -- 156 160 

5-13-2000 2309 191 -- -- -- 142 100 

5-18-2000 1850 291 -- -- -- 601 160 

5-18-2000 1857 324 -- -- -- 569 200 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 136-04 (catch basin outflow)—Continued

5-18-2000 1903 311 -- -- -- 496 180 

5-18-2000 1909 288 -- -- -- 433 170 

5-18-2000 1914 272 -- -- -- 382 170 

5-18-2000 1931 226 -- -- -- 340 160 

5-18-2000 0647 202 -- -- -- 365 120 

5-19-2000 0707 202 -- -- -- 370 170 

5-19-2000 0005 180 -- -- -- 379 120 

5-23-2000 0015 177 -- -- -- 254 120 

5-23-2000 0024 156 -- -- -- 165 100 

5-23-2000 0031 163 -- -- -- 108 90 

5-23-2000 0040 134 -- -- -- 81 95 

5-23-2000 0054 106 -- -- -- 77 85 

5-23-2000 0113 84 -- -- -- 83 70 

5-23-2000 0117 132 -- -- -- 306 110 

5-24-2000 0155 150 -- -- -- 313 140 

5-24-2000 0709 237 -- -- -- 83 150 

5-24-2000 0735 169 -- -- -- 67 130 

5-24-2000 0805 147 -- -- -- 81 140 

5-24-2000 0832 148 -- -- -- 85 130 

5-24-2000 0911 197 -- -- -- 163 150 

5-24-2000 0949 228 -- -- -- 125 190 

5-24-2000 1006 216 -- -- -- 123 190 

5-24-2000 1028 154 -- -- -- 237 130 

5-24-2000 2103 119 -- -- -- 265 110 

5-25-2000 0715 392 -- -- -- 282 250 

5-25-2000 0937 396 -- -- -- 282 300 

5-25-2000 0948 390 -- -- -- 284 320 

5-25-2000 0956 341 -- -- -- 288 290 

5-25-2000 1145 367 -- -- -- 340 320 

6-06-2000 10829 216 -- -- -- -- -- 

6-06-2000 11203 165 -- -- -- 227 -- 

6-06-2000 11359 119 -- -- -- 82 -- 

6-06-2000 11524 71 -- -- -- 85 -- 

6-06-2000 12038 62 -- -- -- 119 -- 

6-07-2000 0837 109 -- -- -- 174 -- 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 136-05 (catch basin inflow)

5-20-1999 0138 -- -- -- -- -- -- 

5-20-1999 0140 -- -- -- -- -- -- 

5-20-1999 0144 -- -- -- -- -- -- 

5-20-1999 0146 -- -- -- -- -- -- 

5-20-1999 0148 -- -- -- -- -- -- 

5-20-1999 0150 -- -- -- -- -- -- 

5-20-1999 0858 -- -- -- -- -- -- 

5-24-1999 1520 -- -- -- -- -- -- 

5-24-1999 1730 -- -- -- -- -- -- 

5-24-1999 1858 269 36 -- -- -- -- 

5-24-1999 1920 -- -- -- -- -- -- 

7-01-1999 0258 669 -- -- -- 190 170 

7-01-1999 0304 297 -- -- -- 104 130 

7-01-1999 0310 95 -- -- -- 87 45 

7-01-1999 0354 735 -- -- -- 240 120 

7-01-1999 0408 -- -- -- -- -- -- 

7-01-1999 0602 441 -- -- -- 101 130 

7-01-1999 0606 841 -- -- -- 65 260 

7-01-1999 0608 1,140 -- -- -- 74 340 

7-01-1999 0610 347 -- -- -- 69 240 

7-01-1999 0614 184 -- -- -- 62 160 

7-01-1999 0616 1,080 -- -- -- 83 120 

7-01-1999 0626 814 -- -- -- 97 110 

7-01-1999 0650 -- -- -- -- -- -- 

7-01-1999 1056 923 -- -- -- 217 330 

7-01-1999 1104 547 -- -- -- 143 230 

7-01-1999 1114 -- -- -- -- -- -- 

7-06-1999 1704 431 -- -- -- 274 110 

7-06-1999 1708 303 -- -- -- 202 100 

7-06-1999 1710 298 -- -- -- 175 130 

7-06-1999 1712 209 -- -- -- 181 820 

7-06-1999 1724 -- -- -- -- -- -- 

7-06-1999 2130 260 -- -- -- 285 150 

7-06-1999 2140 -- -- -- -- -- -- 

7-19-1999 1646 301 -- -- -- 142 110 

7-19-1999 1652 169 -- -- -- 106 80 

7-19-1999 1654 301 -- -- -- -- -- 

7-19-1999 1700 203 -- -- -- 83 65 

7-19-1999 1708 122 -- -- -- 83 85 

7-19-1999 1720 134 -- -- -- 67 70 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 136-05 (catch basin inflow)—Continued

7-19-1999 1724 111 -- -- -- 54 70 

7-19-1999 1732 51 -- -- -- 64 45 

7-19-1999 1750 238 -- -- -- 294 130 

7-23-1999 0100 253 -- -- -- 257 140 

7-23-1999 0104 224 -- -- -- 192 130 

7-23-1999 0108 195 -- -- -- 166 120 

7-23-1999 0110 147 -- -- -- 139 85 

7-23-1999 0112 133 -- -- -- 124 80 

7-23-1999 0116 95 -- -- -- 121 65 

7-23-1999 0124 80 -- -- -- 124 75 

7-23-1999 0136 56 -- -- -- 119 55 

7-23-1999 0146 72 -- -- -- 104 50 

7-23-1999 0156 56 -- -- -- 93 45 

7-23-1999 0204 38 -- -- -- 107 27 

7-24-1999 2026 634 -- -- -- 143 170 

7-24-1999 2030 790 -- -- -- 100 200 

7-24-1999 2032 709 -- -- -- 92 230 

7-24-1999 2034 480 -- -- -- 98 180 

7-24-1999 2036 317 -- -- -- 89 140 

7-24-1999 2040 198 -- -- -- 87 110 

7-24-1999 2050 113 -- -- -- 106 75 

7-24-1999 2108 377 -- -- -- 101 140 

7-24-1999 2112 432 -- -- -- 90 160 

7-24-1999 2114 301 -- -- -- 75 110 

7-24-1999 2116 212 -- -- -- 67 95 

7-24-1999 2120 173 -- -- -- 66 85 

7-25-1999 1642 167 -- -- -- 153 80 

7-25-1999 1646 191 -- -- -- 132 85 

7-25-1999 1648 115 -- -- -- 111 75 

7-25-1999 1656 77 -- -- -- 100 50 

8-06-1999 2144 -- -- -- -- -- -- 

8-14-1999 2136 -- -- -- -- -- -- 

8-14-1999 2140 -- -- -- -- -- -- 

8-21-1999 2058 -- -- -- -- -- -- 

8-21-1999 2100 -- -- -- -- -- -- 

8-21-1999 2132 -- -- -- -- -- -- 

8-21-1999 2232 -- -- -- -- -- -- 

8-21-1999 2336 -- -- -- -- -- -- 

8-22-1999 0116 -- -- -- -- -- -- 

8-22-1999 0212 -- -- -- -- -- -- 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 136-05 (catch basin inflow)—Continued

8-22-1999 0606 -- -- -- -- -- -- 

8-22-1999 0640 -- -- -- -- -- -- 

8-22-1999 0706 -- -- -- -- -- -- 

8-22-1999 0746 -- -- -- -- -- -- 

8-26-1999 1724 183 -- -- -- 293 110 

8-26-1999 1838 -- -- -- -- -- -- 

9-06-1999 1124 -- -- -- -- -- -- 

9-06-1999 1136 144 -- -- -- 140 250 

9-06-1999 1150 -- -- -- -- -- -- 

9-06-1999 1154 -- -- -- -- -- -- 

9-06-1999 1204 -- -- -- -- -- -- 

9-07-1999 0232 -- -- -- -- -- -- 

9-07-1999 0236 -- -- -- -- -- -- 

9-07-1999 0246 -- -- -- -- -- -- 

9-07-1999 0356 -- -- -- -- -- -- 

9-07-1999 0406 109 -- -- -- 71 75 

9-07-1999 0410 -- -- -- -- -- -- 

9-07-1999 0416 -- -- -- -- -- -- 

9-07-1999 0440 -- -- -- -- -- -- 

9-07-1999 0456 -- -- -- -- -- -- 

9-08-1999 0914 203 -- -- -- 173 230 

9-08-1999 0922 246 -- -- -- 166 240 

9-08-1999 0932 -- -- -- -- -- -- 

9-08-1999 0950 -- -- -- -- -- -- 

9-08-1999 1008 -- -- -- -- -- -- 

9-08-1999 1058 -- -- -- -- -- -- 

9-10-1999 0742 -- -- -- -- -- -- 

9-10-1999 0754 -- -- -- -- -- -- 

9-10-1999 0810 -- -- -- -- -- -- 

9-10-1999 0820 -- -- -- -- -- -- 

9-10-1999 0824 183 -- -- -- 53 95 

9-10-1999 0828 -- -- -- -- 50 110 

9-10-1999 0836 142 -- -- -- 70 110 

9-10-1999 0850 169 -- -- -- 86 140 

9-10-1999 0904 -- -- -- -- 191 27 

9-10-1999 0930 -- -- -- -- -- -- 

9-10-1999 0956 180 -- -- -- 70 130 

9-10-1999 1004 153 -- -- -- 84 130 

9-10-1999 1042 -- -- -- -- -- -- 

9-10-1999 1222 -- -- -- -- -- -- 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 136-05 (catch basin inflow)—Continued

9-10-1999 1300 -- -- -- -- -- -- 

9-10-1999 1426 -- -- -- -- -- -- 

9-10-1999 1444 -- -- -- -- 90 90 

9-10-1999 1452 180 -- -- -- 72 130 

9-10-1999 1500 144 -- -- -- 70 95 

9-10-1999 1506 124 -- -- -- 43 75 

9-10-1999 1510 90 -- -- -- 41 65 

9-10-1999 1514 -- -- -- -- 41 55 

9-10-1999 1522 139 -- -- -- 62 50 

9-15-1999 1846 13,600 -- -- -- 430 300 

9-15-1999 1908 1,610 -- -- -- 263 210 

9-15-1999 1928 278 -- -- -- 173 150 

9-15-1999 1946 175 -- -- -- 122 90 

9-15-1999 2000 236 -- -- -- 100 130 

9-15-1999 2010 141 -- -- -- 88 100 

9-15-1999 2022 78 -- -- -- 76 85 

9-15-1999 2038 77 -- -- -- 78 75 

9-15-1999 2052 108 -- -- -- 76 110 

9-15-1999 2104 96 -- -- -- 69 90 

9-15-1999 2116 63 -- -- -- 65 75 

9-15-1999 2130 63 -- -- -- 63 65 

9-15-1999 2156 -- -- -- -- 70 60 

9-15-1999 2256 -- -- -- -- -- -- 

9-15-1999 2320 86 -- -- -- 76 95 

9-15-1999 2332 92 -- -- -- 54 85 

9-15-1999 2348 104 -- -- -- 219 70 

9-16-1999 0000 70 -- -- -- 43 65 

9-16-1999 0010 90 -- -- -- 38 65 

9-16-1999 0020 81 -- -- -- 36 70 

9-16-1999 0028 44 -- -- -- 32 40 

9-16-1999 0042 32 -- -- -- 30 34 

9-16-1999 0054 32 -- -- -- 37 31 

9-16-1999 0142 -- -- -- -- -- -- 

9-22-1999 2336 393 -- -- -- 152 210 

9-22-1999 2354 -- -- -- -- -- -- 

9-23-1999 0204 -- -- -- -- -- -- 

10-18-1999 0712 -- -- -- -- -- -- 

10-20-1999 0756 5,600 -- -- -- 195 480 

10-20-1999 0818 2,030 -- -- -- 165 350 

10-20-1999 0842 2,570 -- -- -- 129 330 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 136-05 (catch basin inflow)—Continued

10-20-1999 0856 660 -- -- -- 88 260 

10-20-1999 0912 344 -- -- -- 90 230 

10-20-1999 0944 294 -- -- -- 112 220 

10-20-1999 1100 323 -- -- -- 142 230 

10-20-1999 1204 394 -- -- -- 65 200 

10-20-1999 1210 259 -- -- -- 48 150 

10-20-1999 1218 152 -- -- -- 38 95 

10-20-1999 1230 148 -- -- -- 39 85 

10-20-1999 1244 94 -- -- -- 40 80 

10-23-1999 0202 125 -- -- -- 117 95 

10-23-1999 0228 170 -- -- -- 134 80 

10-23-1999 0256 104 -- -- -- 103 95 

10-23-1999 0318 167 -- -- -- 68 120 

10-23-1999 0334 120 -- -- -- 47 85 

10-23-1999 0346 149 -- -- -- 35 75 

10-23-1999 0402 186 -- -- -- 39 80 

10-23-1999 0414 89 -- -- -- 36 55 

10-23-1999 0446 -- -- -- -- -- -- 

10-23-1999 0640 169 -- -- -- 136 180 

10-23-1999 0908 -- -- -- -- -- -- 

11-02-1999 2354 163 -- -- -- 153 110 

11-03-1999 0038 145 -- -- -- 97 150 

11-03-1999 0118 112 -- -- -- 71 95 

11-03-1999 0138 80 -- -- -- 46 60 

11-03-1999 0152 93 -- -- -- 34 60 

11-03-1999 0210 336 -- -- -- 38 110 

11-03-1999 0234 243 -- -- -- 41 70 

11-03-1999 0254 58 -- -- -- 39 34 

12-20-1999 2325 1,800 -- -- -- 53 760 

2-14-2000 0753 429 -- -- -- 1,650 310 

2-14-2000 0813 467 -- -- -- 1,560 450 

2-14-2000 0838 -- -- -- -- -- -- 

2-14-2000 0924 -- -- -- -- -- -- 

2-14-2000 0925 1,520 -- -- -- 1,570 1,000 

2-14-2000 0933 -- -- -- -- -- -- 

2-14-2000 0938 1,070 -- -- -- 1,080 750 

2-14-2000 1016 835 -- -- -- 1,090 550 

2-14-2000 1057 685 -- -- -- 1,580 500 

2-14-2000 1125 1,930 -- -- -- 1,260 750 

2-14-2000 1138 883 -- -- -- 1,200 500 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 136-05 (catch basin inflow)—Continued

2-14-2000 1150 2,750 -- -- -- 884 600 

2-14-2000 1155 2,880 -- -- -- 574 750 

2-14-2000 1159 1,790 -- -- -- 562 600 

2-14-2000 1209 1,100 -- -- -- 932 600 

2-28-2000 0753 1,870 -- -- -- 21,800 1,100 

2-28-2000 0804 -- -- -- -- -- -- 

2-28-2000 0814 -- -- -- -- -- -- 

2-28-2000 0823 1,960 -- -- -- 1,170 1,100 

2-28-2000 0831 -- -- -- -- -- -- 

2-28-2000 0843 -- -- -- -- -- -- 

3-28-2000 0451 1,290 52 9 42 7,120 700 

3-28-2000 0459 999 31 7 24 6,480 800 

3-28-2000 0506 675 20 5 15 4,730 650 

3-28-2000 0511 558 16 5 12 3,370 500 

3-28-2000 0517 1,210 63 10 53 2,800 450 

3-28-2000 0541 731 30 8 22 2,890 500 

3-28-2000 0559 477 13 3 10 2,560 450 

3-28-2000 0618 685 12 5 7 1,680 600 

3-28-2000 0630 509 12 4 8 1,170 400 

3-28-2000 0643 320 25 9 16 1,040 220 

3-28-2000 0700 505 9 4 5 638 350 

3-28-2000 0708 367 44 6 38 603 180 

3-28-2000 0721 322 28 10 19 570 180 

3-28-2000 0754 332 9 5 4 472 220 

3-28-2000 0804 213 6 2 3 451 160 

3-28-2000 0816 162 7 3 4 460 120 

4-04-2000 0342 960 -- -- -- 925 750 

4-08-2000 2319 1,670 -- -- -- 827 750 

4-08-2000 2323 791 -- -- -- 820 600 

4-08-2000 2329 609 -- -- -- 783 270 

4-09-2000 0149 366 -- -- -- 534 170 

4-09-2000 0156 319 -- -- -- 468 160 

4-09-2000 0214 225 -- -- -- 460 170 

4-09-2000 0304 210 -- -- -- 301 100 

4-09-2000 0323 72 -- -- -- 290 70 

4-09-2000 0428 64 -- -- -- 288 60 

4-09-2000 0450 487 -- -- -- 182 220 

4-09-2000 0508 362 -- -- -- 133 130 

4-09-2000 0517 165 -- -- -- 110 110 

4-09-2000 0529 98 -- -- -- 134 60 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 136-05 (catch basin inflow)—Continued

4-09-2000 0549 188 -- -- -- 218 110 

4-09-2000 0611 363 -- -- -- 153 65 

4-09-2000 0625 117 -- -- -- 133 65 

4-09-2000 0721 289 -- -- -- 238 150 

4-09-2000 0743 149 -- -- -- 127 75 

4-18-2000 1849 317 -- -- -- 596 160 

4-18-2000 1900 366 -- -- -- 467 180 

4-21-2000 1939 508 -- -- -- 308 160 

4-21-2000 1949 510 -- -- -- 173 160 

4-21-2000 1956 359 -- -- -- 114 190 

4-21-2000 2002 517 -- -- -- 99 140 

4-21-2000 2017 670 -- -- -- 125 110 

4-21-2000 2113 574 -- -- -- 190 120 

4-21-2000 2126 212 -- -- -- 112 130 

4-21-2000 2147 120 -- -- -- 82 90 

4-21-2000 2236 224 -- -- -- 81 95 

4-21-2000 2253 156 -- -- -- 63 60 

4-21-2000 2311 61 -- -- -- 68 50 

4-21-2000 2341 57 -- -- -- 96 60 

4-22-2000 0002 66 -- -- -- 82 60 

4-22-2000 0019 79 -- -- -- 69 60 

4-22-2000 0033 69 -- -- -- 61 55 

4-22-2000 0056 64 -- -- -- 60 50 

4-22-2000 0114 74 -- -- -- 46 51 

4-22-2000 0129 77 -- -- -- 44 50 

4-22-2000 0227 74 -- -- -- 69 40 

4-22-2000 0327 111 -- -- -- 146 60 

4-23-2000 1648 -- -- -- -- -- -- 

5-02-2000 0642 9,920 -- -- -- 679 500 

5-02-2000 0806 1,970 -- -- -- 390 380 

5-02-2000 0817 1,070 -- -- -- 348 350 

5-02-2000 0830 -- -- -- -- -- 6 

5-08-2000 1712 1,090 -- -- -- 621 380 

5-08-2000 1714 1,310 -- -- -- 565 500 

5-08-2000 1717 677 -- -- -- 431 360 

5-08-2000 1720 530 -- -- -- 452 260 

5-08-2000 1724 471 -- -- -- 415 230 

5-08-2000 1736 300 -- -- -- 490 170 

5-10-2000 1330 402 -- -- -- 258 220 

5-10-2000 2029 820 -- -- -- 141 350 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 136-05 (catch basin inflow)—Continued

5-10-2000 2031 891 -- -- -- 103 400 

5-10-2000 2033 643 -- -- -- 89 340 

5-10-2000 2037 471 -- -- -- 78 160 

5-10-2000 2055 306 -- -- -- 117 170 

5-10-2000 2117 221 -- -- -- 157 180 

5-10-2000 2202 247 -- -- -- 175 210 

5-10-2000 2221 246 -- -- -- 159 200 

5-10-2000 2229 229 -- -- -- 71 140 

5-10-2000 2237 107 -- -- -- 40 65 

5-11-2000 0008 115 -- -- -- 101 100 

5-13-2000 2249 366 -- -- -- 174 120 

5-13-2000 2253 284 -- -- -- 141 120 

5-13-2000 2309 82 -- -- -- 190 40 

5-18-2000 1850 756 -- -- -- 424 220 

5-18-2000 1857 558 -- -- -- 410 250 

5-18-2000 1903 302 -- -- -- 331 210 

5-18-2000 1909 471 -- -- -- 269 220 

5-18-2000 1914 303 -- -- -- 244 170 

5-18-2000 1931 226 -- -- -- 286 170 

5-18-2000 0647 323 -- -- -- 431 230 

5-19-2000 0707 271 -- -- -- 254 190 

5-19-2000 0005 426 -- -- -- 189 130 

5-23-2000 0015 263 -- -- -- 116 110 

5-23-2000 0024 241 -- -- -- 79 85 

5-23-2000 0031 256 -- -- -- 62 95 

5-23-2000 0040 171 -- -- -- 63 110 

5-23-2000 0054 100 -- -- -- 79 70 

5-23-2000 0113 64 -- -- -- 99 50 

5-23-2000 0117 343 -- -- -- 255 230 

5-24-2000 0155 367 -- -- -- 278 210 

5-24-2000 0709 162 -- -- -- 89 95 

5-24-2000 0735 105 -- -- -- 84 95 

5-24-2000 0805 163 -- -- -- 94 150 

5-24-2000 0832 135 -- -- -- 86 130 

5-24-2000 0911 278 -- -- -- 310 140 

5-24-2000 0949 264 -- -- -- 148 230 

5-24-2000 1006 300 -- -- -- 139 230 

5-24-2000 1028 117 -- -- -- 221 80 

5-24-2000 2103 769 -- -- -- 390 620 

5-25-2000 0715 -- -- -- -- -- -- 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 136-05 (catch basin inflow)—Continued

5-25-2000 0937 -- -- -- -- -- -- 

5-25-2000 0948 -- -- -- -- -- -- 

5-25-2000 0956 -- -- -- -- -- -- 

5-25-2000 1145 -- -- -- -- -- -- 

6-06-2000 10829 347 -- -- -- 16 -- 

6-06-2000 11203 142 -- -- -- 152 -- 

6-06-2000 11359 135 -- -- -- 92 -- 

6-06-2000 11524 86 -- -- -- 75 -- 

6-06-2000 12038 34 -- -- -- 111 -- 

6-07-2000 0837 -- -- -- -- -- -- 

Monitoring location 739-02 (oil-grit separator outflow)

8-21-1999 2203 -- -- -- -- -- -- 

8-21-1999 2210 -- -- -- -- -- -- 

8-21-1999 2216 -- -- -- -- -- -- 

8-21-1999 2223 -- -- -- -- -- -- 

8-21-1999 2229 -- -- -- -- -- -- 

8-21-1999 2236 -- -- -- -- -- -- 

8-21-1999 2249 -- -- -- -- -- -- 

8-21-1999 2302 -- -- -- -- -- -- 

8-21-1999 2315 -- -- -- -- -- -- 

8-21-1999 2328 -- -- -- -- -- -- 

8-21-1999 2341 -- -- -- -- -- -- 

8-21-1999 2354 -- -- -- -- -- -- 

8-22-1999 0212 -- -- -- -- -- -- 

8-22-1999 0235 -- -- -- -- -- -- 

8-22-1999 0257 -- -- -- -- -- -- 

8-22-1999 0824 -- -- -- -- -- -- 

8-27-1999 1600 -- -- -- -- -- -- 

8-27-1999 1647 -- -- -- -- -- -- 

9-06-1999 1149 -- -- -- -- -- -- 

9-06-1999 1206 -- -- -- -- -- -- 

9-07-1999 0228 -- -- -- -- -- -- 

9-07-1999 0237 -- -- -- -- -- -- 

9-07-1999 0401 -- -- -- -- -- -- 

9-07-1999 0415 -- -- -- -- -- -- 

9-08-1999 1014 87 -- -- -- -- -- 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 739-02 (oil-grit separator outflow)—Continued

9-08-1999 1021 -- -- -- -- -- -- 

9-08-1999 1056 87 -- -- -- 248 95 

9-10-1999 0815 100 -- -- -- 278 100 

9-10-1999 0816 -- -- -- -- -- -- 

9-10-1999 0822 158 -- -- -- 197 120 

9-10-1999 0823 -- -- -- -- -- -- 

9-10-1999 0838 120 -- -- -- 132 85 

9-10-1999 0851 -- -- -- -- -- -- 

9-10-1999 0941 -- -- -- -- -- -- 

9-10-1999 0956 101 -- -- -- 148 90 

9-10-1999 1504 109 -- -- -- 170 110 

9-10-1999 1535 95 -- -- -- 99 85 

9-10-1999 1536 -- -- -- -- -- -- 

9-10-1999 1629 55 -- -- -- 87 55 

9-10-1999 1631 -- -- -- -- -- -- 

9-10-1999 1726 37 -- -- -- 77 36 

9-10-1999 1736 -- -- -- -- -- -- 

9-10-1999 1744 124 -- -- -- 67 60 

9-10-1999 1805 80 -- -- -- 46 45 

9-10-1999 1833 85 -- -- -- 50 45 

9-10-1999 1837 190 -- -- -- 46 75 

9-10-1999 1844 -- -- -- -- -- -- 

9-10-1999 1855 71 -- -- -- 36 45 

9-10-1999 1905 -- -- -- -- -- -- 

9-10-1999 1939 -- -- -- -- -- -- 

9-10-1999 1950 37 -- -- -- 41 32 

9-10-1999 2010 145 -- -- -- 44 55 

9-10-1999 2012 -- -- -- -- -- -- 

9-10-1999 2021 70 -- -- -- 33 39 

9-10-1999 2034 -- -- -- -- -- -- 

9-10-1999 2052 29 -- -- -- 35 22 

9-10-1999 2100 -- -- -- -- -- -- 

9-10-1999 2119 -- -- -- -- -- -- 

9-10-1999 2137 -- -- -- -- -- -- 

9-10-1999 2138 -- -- -- -- -- -- 

9-10-1999 2144 -- -- -- -- -- -- 

9-10-1999 2145 52 -- -- -- 23 25 

9-10-1999 2153 -- -- -- -- -- -- 

9-10-1999 2159 -- -- -- -- -- -- 

9-15-1999 1910 57 -- -- -- 282 65 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 739-02 (oil-grit separator outflow)—Continued

9-15-1999 1946 -- -- -- -- -- -- 

9-15-1999 1947 81 -- -- -- 243 85 

9-15-1999 2009 -- -- -- -- -- -- 

9-15-1999 2011 81 -- -- -- 174 85 

9-15-1999 2040 -- -- -- -- -- -- 

9-15-1999 2041 79 -- -- -- 141 80 

9-15-1999 2102 -- -- -- -- -- -- 

9-15-1999 2111 60 -- -- -- 109 65 

9-15-1999 2136 -- -- -- -- -- -- 

9-15-1999 2139 51 -- -- -- 105 60 

9-15-1999 2211 -- -- -- -- -- -- 

9-15-1999 2316 44 -- -- -- 115 55 

9-15-1999 2331 -- -- -- -- -- -- 

9-15-1999 2355 47 -- -- -- 86 50 

9-16-1999 0008 -- -- -- -- -- -- 

9-16-1999 0026 44 -- -- -- 66 50 

9-16-1999 0032 -- -- -- -- -- -- 

9-16-1999 0045 38 -- -- -- 56 39 

9-16-1999 0049 -- -- -- -- -- -- 

9-16-1999 0103 29 -- -- -- 51 34 

9-16-1999 0111 -- -- -- -- -- -- 

9-16-1999 0635 38 -- -- -- 140 50 

9-16-1999 0658 -- -- -- -- -- -- 

9-16-1999 0826 49 -- -- -- 154 65 

9-16-1999 0837 -- -- -- -- -- -- 

9-16-1999 0859 81 -- -- -- 114 80 

9-16-1999 0906 -- -- -- -- -- -- 

9-16-1999 0928 88 -- -- -- 82 75 

9-16-1999 0929 -- -- -- -- -- -- 

9-16-1999 0939 99 -- -- -- 62 70 

9-16-1999 1013 80 -- -- -- 39 60 

9-16-1999 1158 -- -- -- -- -- -- 

9-16-1999 1204 37 -- -- -- 71 45 

9-16-1999 1414 -- -- -- -- -- -- 

9-16-1999 1417 55 -- -- -- 85 50 

9-16-1999 1519 110 -- -- -- 68 50 

9-16-1999 1532 -- -- -- -- -- -- 

9-16-1999 1538 80 -- -- -- 42 26 

9-16-1999 1550 -- -- -- -- -- -- 

9-16-1999 1556 66 -- -- -- 41 32 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 739-02 (oil-grit separator outflow)—Continued

9-16-1999 1605 -- -- -- -- -- -- 

9-16-1999 1612 81 -- -- -- 40 32 

9-16-1999 1639 -- -- -- -- -- -- 

9-16-1999 1651 28 -- -- -- 44 18 

9-22-1999 2332 77 -- -- -- 401 50 

9-22-1999 2333 -- -- -- -- -- -- 

9-22-1999 2335 -- -- -- -- -- -- 

9-22-1999 2336 -- -- -- -- -- -- 

9-22-1999 2338 -- -- -- -- -- -- 

9-22-1999 2339 -- -- -- -- -- -- 

9-22-1999 2340 -- -- -- -- -- -- 

9-22-1999 2341 -- -- -- -- -- -- 

9-22-1999 2342 -- -- -- -- -- -- 

9-22-1999 2344 -- -- -- -- -- -- 

9-22-1999 2345 -- -- -- -- -- -- 

9-22-1999 2346 -- -- -- -- -- -- 

9-22-1999 2347 -- -- -- -- -- -- 

9-22-1999 2348 -- -- -- -- -- -- 

9-22-1999 2349 -- -- -- -- -- -- 

9-22-1999 2350 -- -- -- -- -- -- 

9-22-1999 2352 -- -- -- -- -- -- 

9-22-1999 2353 -- -- -- -- -- -- 

9-22-1999 2354 -- -- -- -- -- -- 

9-22-1999 2355 -- -- -- -- -- -- 

9-22-1999 2356 -- -- -- -- -- -- 

9-22-1999 2357 -- -- -- -- -- -- 

9-22-1999 2358 -- -- -- -- -- -- 

9-22-1999 2359 -- -- -- -- -- -- 

9-23-1999 0001 -- -- -- -- -- -- 

10-09-1999 0800 50 -- -- -- 195 37 

10-10-1999 1415 -- -- -- -- -- -- 

10-10-1999 1423 64 -- -- -- 297 36 

10-10-1999 1449 -- -- -- -- -- -- 

10-10-1999 1458 56 -- -- -- 270 37 

10-10-1999 1524 -- -- -- -- -- -- 

10-10-1999 1544 50 -- -- -- 231 37 

10-10-1999 1603 37 -- -- -- 206 27 

10-10-1999 1612 227 -- -- -- 164 110 

10-10-1999 1621 295 -- -- -- 104 150 

10-10-1999 1630 316 -- -- -- 74 120 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 739-02 (oil-grit separator outflow)—Continued

10-10-1999 1639 280 -- -- -- 60 110 

10-10-1999 1648 273 -- -- -- 49 90 

10-10-1999 1657 286 -- -- -- 45 80 

10-10-1999 1706 250 -- -- -- 41 60 

10-10-1999 1715 188 -- -- -- 40 65 

10-10-1999 1724 159 -- -- -- 40 60 

10-10-1999 1733 137 -- -- -- 38 60 

10-10-1999 1742 121 -- -- -- 38 55 

10-10-1999 1800 -- -- -- -- -- -- 

10-10-1999 1801 115 -- -- -- 37 55 

10-13-1999 2255 -- -- -- -- -- -- 

10-13-1999 2258 109 -- -- -- 48 60 

10-13-1999 2300 -- -- -- -- -- -- 

10-13-1999 2302 -- -- -- -- -- -- 

10-13-1999 2303 -- -- -- -- -- -- 

10-13-1999 2304 87 -- -- -- 108 60 

10-13-1999 2306 71 -- -- -- 68 50 

10-13-1999 2308 -- -- -- -- -- -- 

10-13-1999 2310 47 -- -- -- 50 31 

10-13-1999 2312 -- -- -- -- -- -- 

10-13-1999 2324 28 -- -- -- 52 22 

10-14-1999 0702 24 -- -- -- 47 19 

10-14-1999 1102 23 -- -- -- 43 18 

10-18-1999 0042 -- -- -- -- -- -- 

10-18-1999 0054 -- -- -- -- -- -- 

10-18-1999 0117 -- -- -- -- -- -- 

10-18-1999 0150 -- -- -- -- -- -- 

10-18-1999 0219 -- -- -- -- -- -- 

10-18-1999 0248 -- -- -- -- -- -- 

10-20-1999 0809 27 -- -- -- 74 25 

10-20-1999 0843 63 -- -- -- 127 65 

10-20-1999 0856 90 -- -- -- 162 95 

10-20-1999 0909 106 -- -- -- 161 120 

10-20-1999 0928 -- -- -- -- -- -- 

10-20-1999 0929 118 -- -- -- 151 120 

10-20-1999 1107 106 -- -- -- 152 130 

10-20-1999 1201 -- -- -- -- -- -- 

10-20-1999 1205 122 -- -- -- 152 140 

10-20-1999 1208 -- -- -- -- -- -- 

10-20-1999 1211 168 -- -- -- 124 150 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 739-02 (oil-grit separator outflow)—Continued

10-20-1999 1216 -- -- -- -- -- -- 

10-20-1999 1220 168 -- -- -- 97 150 

10-20-1999 1226 -- -- -- -- -- -- 

10-20-1999 1231 144 -- -- -- 80 20 

10-20-1999 1236 -- -- -- -- -- -- 

10-20-1999 1240 128 -- -- -- 69 120 

10-20-1999 1245 -- -- -- -- -- -- 

10-20-1999 1250 112 -- -- -- 63 110 

10-20-1999 1256 -- -- -- -- -- -- 

10-20-1999 1303 101 -- -- -- 57 95 

10-20-1999 1311 -- -- -- -- -- -- 

10-20-1999 1319 92 -- -- -- 58 90 

10-20-1999 1325 -- -- -- -- -- -- 

10-20-1999 1331 100 -- -- -- 57 85 

10-20-1999 1336 -- -- -- -- -- -- 

10-20-1999 1344 85 -- -- -- 55 85 

10-20-1999 1407 -- -- -- -- -- -- 

10-20-1999 1420 64 -- -- -- 53 60 

10-20-1999 1504 -- -- -- -- -- -- 

10-20-1999 1523 58 -- -- -- 74 65 

10-20-1999 1649 -- -- -- -- -- -- 

10-20-1999 1801 46 -- -- -- 104 55 

10-20-1999 1805 -- -- -- -- -- -- 

10-20-1999 1817 -- -- -- -- -- -- 

10-20-1999 1829 -- -- -- -- -- -- 

10-20-1999 1841 -- -- -- -- -- -- 

10-23-1999 0152 34 -- -- -- 128 45 

10-23-1999 0207 41 -- -- -- 145 50 

10-23-1999 0220 54 -- -- -- 160 60 

10-23-1999 0239 54 -- -- -- 165 55 

10-23-1999 0257 52 -- -- -- 163 55 

10-23-1999 0325 46 -- -- -- 146 55 

10-23-1999 0342 52 -- -- -- 119 55 

10-23-1999 0354 56 -- -- -- 94 55 

10-23-1999 0411 48 -- -- -- 75 45 

10-23-1999 0427 46 -- -- -- 63 45 

10-23-1999 0502 38 -- -- -- 57 37 

10-23-1999 0528 34 -- -- -- 58 35 

10-23-1999 0535 32 -- -- -- 59 34 

10-23-1999 0544 33 -- -- -- 60 34 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 739-02 (oil-grit separator outflow)—Continued

10-23-1999 0556 30 -- -- -- 60 34 

10-23-1999 0628 32 -- -- -- 61 33 

10-23-1999 0644 30 -- -- -- 62 33 

10-23-1999 0657 29 -- -- -- 63 34 

10-23-1999 0711 29 -- -- -- 65 34 

10-23-1999 0730 28 -- -- -- 69 35 

11-02-1999 2343 -- -- -- -- -- -- 

11-03-1999 0001 25 12 88 -- 149 31 

11-03-1999 0020 60 5 95 -- 253 75 

11-03-1999 0036 92 7 93 -- 291 110 

11-03-1999 0112 107 18 82 -- 287 130 

11-03-1999 0131 102 6 94 -- 235 130 

11-03-1999 0142 90 7 93 -- 183 110 

11-03-1999 0152 92 6 94 -- 146 100 

11-03-1999 0203 84 11 89 -- 114 85 

11-03-1999 0213 75 9 91 -- 93 75 

11-03-1999 0224 64 2 98 -- 80 65 

11-03-1999 0239 69 12 88 -- 72 60 

11-03-1999 0255 68 6 94 -- 66 50 

11-03-1999 0309 42 8 92 -- 66 50 

11-03-1999 0325 48 11 89 -- 68 45 

11-03-1999 0359 39 1 99 -- 69 40 

11-03-1999 0418 36 12 88 -- 74 38 

11-03-1999 0455 46 13 87 -- 64 37 

11-03-1999 0613 32 4 96 -- 56 31 

11-03-1999 0737 35 3 97 -- 68 36 

11-03-1999 0810 59 1 99 -- 91 70 

11-03-1999 0829 52 17 83 -- 94 70 

11-10-1999 2314 67 -- -- -- 96 70 

11-12-1999 2318 62 -- -- -- 169 70 

11-12-1999 2343 94 -- -- -- 200 100 

11-14-1999 1743 74 -- -- -- 254 75 

12-15-1999 0310 -- -- -- -- -- -- 

12-15-1999 0504 -- -- -- -- -- -- 

12-15-1999 0550 -- -- -- -- -- -- 

12-21-1999 10057 130 -- -- -- 305 120 

1-10-2000 1900 -- -- -- -- -- -- 

1-10-2000 1919 -- -- -- -- -- -- 

1-10-2000 1959 -- -- -- -- -- -- 

1-10-2000 2028 -- -- -- -- -- -- 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 739-02 (oil-grit separator outflow)—Continued

1-10-2000 2031 -- -- -- -- -- -- 

1-10-2000 2034 -- -- -- -- -- -- 

1-10-2000 2038 -- -- -- -- -- -- 

1-10-2000 2041 -- -- -- -- -- -- 

1-10-2000 2045 -- -- -- -- -- -- 

1-10-2000 2049 -- -- -- -- -- -- 

1-10-2000 2054 -- -- -- -- -- -- 

1-10-2000 2058 -- -- -- -- -- -- 

1-10-2000 2103 -- -- -- -- -- -- 

1-10-2000 2109 -- -- -- -- -- -- 

1-10-2000 2115 -- -- -- -- -- -- 

1-10-2000 2122 -- -- -- -- -- -- 

1-10-2000 2130 -- -- -- -- -- -- 

1-13-2000 1023 -- -- -- -- -- -- 

1-31-2000 0416 -- -- -- -- -- -- 

1-31-2000 0432 38 -- -- -- 53,300 32 

1-31-2000 0444 259 -- -- -- 57,400 260 

1-31-2000 0457 362 -- -- -- 50,900 400 

1-31-2000 0515 384 -- -- -- 39,500 450 

1-31-2000 0532 -- -- -- -- -- -- 

1-31-2000 0547 404 -- -- -- 24,100 380 

1-31-2000 0601 -- -- -- -- -- -- 

1-31-2000 0618 322 -- -- -- 15,900 350 

1-31-2000 0656 -- -- -- -- -- -- 

1-31-2000 0701 420 -- -- -- 12,800 500 

1-31-2000 0705 -- -- -- -- -- -- 

1-31-2000 0708 429 -- -- -- 12,500 500 

1-31-2000 0712 -- -- -- -- -- -- 

1-31-2000 0716 435 -- -- -- 12,400 550 

1-31-2000 0717 -- -- -- -- -- -- 

1-31-2000 0722 -- -- -- -- -- -- 

1-31-2000 0726 421 -- -- -- 12,300 500 

1-31-2000 0727 -- -- -- -- -- -- 

1-31-2000 0734 -- -- -- -- -- -- 

1-31-2000 0740 410 -- -- -- 12,300 500 

2-14-2000 0204 1,000 -- -- -- 13,600 22 

2-14-2000 0210 5 -- -- -- 14,800 8 

2-14-2000 0222 763 -- -- -- 16,400 550 

2-14-2000 0234 -- -- -- -- 24,800 100 

2-14-2000 0243 -- -- -- -- -- -- 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 739-02 (oil-grit separator outflow)—Continued

2-14-2000 0259 995 -- -- -- 11,000 450 

2-14-2000 0335 765 0 100 -- 10,500 450 

2-14-2000 0338 1,220 -- -- -- 10,100 390 

2-14-2000 0349 1,200 -- -- -- 9,600 380 

2-14-2000 0400 966 -- -- -- -- -- 

2-14-2000 0404 906 -- -- -- 9,490 390 

2-14-2000 0407 -- -- -- -- 9,360 360 

2-14-2000 0411 1,120 -- -- -- 9,210 350 

2-14-2000 0415 907 -- -- -- 9,060 340 

2-14-2000 0420 903 -- -- -- 8,660 340 

2-14-2000 0425 351 1 99 -- 8,840 380 

2-14-2000 0430 972 -- -- -- 8,730 330 

2-14-2000 0434 896 -- -- -- 8,630 340 

2-14-2000 0438 791 -- -- -- 8,620 330 

2-14-2000 0449 1,100 -- -- -- 8,400 370 

2-14-2000 0526 944 -- -- -- 7,130 400 

2-14-2000 0552 962 -- -- -- 6,290 500 

2-14-2000 0602 852 -- -- -- 5,900 600 

2-14-2000 0608 1,040 0 100 -- 5,610 650 

2-14-2000 1152 666 2 98 -- 4,960 550 

2-14-2000 1157 -- -- -- -- -- -- 

2-14-2000 1206 545 -- -- -- 1,800 400 

2-14-2000 1222 591 -- -- -- 2,120 380 

2-14-2000 1250 562 -- -- -- 1,890 390 

2-14-2000 1309 484 -- -- -- -- -- 

2-25-2000 1506 -- -- -- -- -- -- 

2-25-2000 1525 2,090 -- -- -- 42,200 550 

2-25-2000 1557 2,170 -- -- -- 18,500 1,100 

2-25-2000 1631 323 -- -- -- 11,200 900 

2-25-2000 1702 555 -- -- -- 8,580 650 

2-25-2000 1734 425 -- -- -- 6,920 550 

2-25-2000 1821 321 2 98 -- 5,950 350 

2-25-2000 1827 297 0 100 -- 5,840 340 

2-25-2000 1835 274 -- -- -- 5,720 330 

2-25-2000 1846 267 -- -- -- 5,610 320 

2-25-2000 1854 261 -- -- -- 5,720 310 

2-25-2000 1941 215 -- -- -- 6,290 260 

2-25-2000 2040 241 -- -- -- 4,220 300 

2-25-2000 2125 201 -- -- -- 3,730 290 

2-25-2000 2205 165 -- -- -- 3,600 230 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 739-02 (oil-grit separator outflow)—Continued

2-25-2000 2305 110 -- -- -- 3,160 190 

2-25-2000 2319 113 7 93 -- 3,060 170 

2-26-2000 0214 -- -- -- -- 3,870 -- 

2-26-2000 0232 104 1 99 -- 4,130 150 

2-26-2000 0723 93 -- -- -- 4,730 130 

2-26-2000 0800 106 -- -- -- 3,770 150 

2-26-2000 0822 108 3 97 -- 6,010 150 

2-28-2000 0906 450 -- -- -- 5,260 500 

2-28-2000 1010 412 0 100 -- 4,030 520 

2-28-2000 1132 343 -- -- -- 2,860 440 

2-28-2000 1149 336 -- -- -- 2,760 400 

2-28-2000 1209 303 -- -- -- 2,700 400 

2-28-2000 1223 308 -- -- -- 2,660 420 

2-28-2000 1240 297 -- -- -- 2,630 400 

3-11-2000 1516 312 -- -- -- 2,750 410 

3-11-2000 1536 29 -- -- -- 2,990 50 

3-11-2000 1603 40 -- -- -- 3,540 75 

3-11-2000 1610 144 -- -- -- 5,170 180 

3-11-2000 1618 242 -- -- -- 5,090 300 

3-11-2000 1625 259 -- -- -- 4,980 340 

3-11-2000 1631 262 -- -- -- 4,820 350 

3-11-2000 1637 269 -- -- -- 4,730 360 

3-11-2000 1715 271 -- -- -- 4,630 370 

3-11-2000 1830 268 -- -- -- 4,510 360 

3-11-2000 1846 237 -- -- -- 3,700 340 

3-11-2000 1859 177 -- -- -- 2,760 210 

3-11-2000 1914 232 -- -- -- 2,600 240 

3-11-2000 1934 247 -- -- -- 2,160 240 

3-11-2000 2020 214 -- -- -- 1,650 190 

3-11-2000 2202 179 -- -- -- 1,100 180 

3-11-2000 2306 120 -- -- -- 731 130 

3-12-2000 0027 66 -- -- -- 744 90 

3-12-2000 0046 56 -- -- -- 734 80 

3-12-2000 0138 68 -- -- -- 822 70 

3-12-2000 0236 127 -- -- -- 1,420 85 

3-12-2000 0822 83 -- -- -- 841 70 

3-28-2000 0446 6 -- -- -- 41,500 10 

3-28-2000 0512 -- -- -- -- -- -- 

3-28-2000 0520 -- -- -- -- -- -- 

3-28-2000 0537 378 -- -- -- 7,390 360 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 739-02 (oil-grit separator outflow)—Continued

3-28-2000 0554 326 -- -- -- 4,300 280 

3-28-2000 0609 330 -- -- -- 3,740 310 

3-28-2000 0622 353 -- -- -- 3,140 300 

3-28-2000 0636 304 -- -- -- 2,610 250 

3-28-2000 0651 -- -- -- -- -- -- 

3-28-2000 0655 -- -- -- -- -- -- 

3-28-2000 0659 -- -- -- -- -- -- 

3-28-2000 0706 386 -- -- -- 2,420 260 

3-28-2000 0719 282 -- -- -- 1,790 220 

3-28-2000 0732 231 -- -- -- 1,520 190 

3-28-2000 0747 186 -- -- -- 1,090 160 

3-28-2000 0831 121 -- -- -- 873 110 

3-28-2000 1059 111 -- -- -- 1,550 130 

3-28-2000 1122 105 -- -- -- 1,640 120 

3-28-2000 1155 -- -- -- -- -- -- 

3-29-2000 0332 -- -- -- -- 2,160 110 

3-29-2000 0355 -- -- -- -- 2,320 110 

3-29-2000 0434 -- -- -- -- -- -- 

3-29-2000 0332 70 -- -- -- -- -- 

3-29-2000 0355 77 -- -- -- -- -- 

4-04-2000 0345 -- -- -- -- -- -- 

4-04-2000 0359 35 -- -- -- 2,050 60 

4-04-2000 0406 38 -- -- -- 2,140 70 

4-04-2000 0417 46 -- -- -- 2,250 70 

4-04-2000 1523 85 -- -- -- 2,660 120 

4-04-2000 1608 199 -- -- -- 2,860 280 

4-04-2000 1729 369 -- -- -- 2,710 460 

4-04-2000 1749 -- -- -- -- -- -- 

4-04-2000 1816 -- -- -- -- -- -- 

4-08-2000 2358 186 -- -- -- 2,800 210 

4-09-2000 0005 187 -- -- -- 2,810 190 

4-09-2000 0013 188 -- -- -- 2,820 190 

4-09-2000 0022 197 -- -- -- 2,880 230 

4-09-2000 0056 245 -- -- -- 3,180 210 

4-09-2000 0119 -- -- -- -- -- -- 

4-09-2000 0146 214 -- -- -- 3,230 250 

4-09-2000 0256 157 -- -- -- 2,750 170 

4-09-2000 0406 90 -- -- -- 1,680 120 

4-09-2000 0458 202 -- -- -- 1,210 190 

4-09-2000 0533 144 -- -- -- 781 120 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 739-02 (oil-grit separator outflow)—Continued

4-09-2000 0610 105 -- -- -- 476 85 

4-09-2000 0653 95 -- -- -- 376 80 

4-09-2000 0731 -- -- -- -- -- -- 

4-09-2000 0751 115 -- -- -- 472 65 

4-09-2000 0918 71 -- -- -- 354 55 

4-09-2000 0944 68 -- -- -- 362 60 

4-09-2000 1019 -- -- -- -- -- -- 

4-11-2000 2043 16 -- -- -- 427 30 

4-11-2000 2113 21 -- -- -- 648 32 

4-11-2000 2149 31 -- -- -- 586 39 

4-16-2000 0817 79 -- -- -- 1,280 100 

4-16-2000 0849 77 -- -- -- 1,317 130 

4-18-2000 1834 -- -- -- -- -- -- 

4-18-2000 1909 120 -- -- -- 1,430 120 

4-18-2000 1957 146 -- -- -- 1,270 200 

4-18-2000 2031 147 -- -- -- 900 150 

4-18-2000 2103 129 -- -- -- 663 140 

4-18-2000 2222 83 -- -- -- 425 100 

4-19-2000 0000 57 -- -- -- 400 70 

4-19-2000 0233 33 -- -- -- 378 50 

4-19-2000 0418 24 -- -- -- 429 45 

4-19-2000 0452 25 -- -- -- 448 40 

4-19-2000 0825 83 -- -- -- 529 110 

4-19-2000 0947 84 -- -- -- 524 140 

4-19-2000 1000 103 -- -- -- 523 140 

4-19-2000 1022 105 -- -- -- 527 110 

4-21-2000 1447 -- -- -- -- -- -- 

4-21-2000 1501 55 -- -- -- 566 95 

4-21-2000 1512 61 -- -- -- 565 100 

4-21-2000 1522 64 -- -- -- 573 100 

4-21-2000 1529 65 -- -- -- 586 110 

4-21-2000 1840 152 -- -- -- 872 220 

4-21-2000 1958 171 -- -- -- 548 180 

4-21-2000 2015 138 -- -- -- 304 130 

4-21-2000 2131 107 -- -- -- 212 85 

4-21-2000 2158 94 -- -- -- 226 75 

4-21-2000 2237 -- -- -- -- -- -- 

4-21-2000 2248 108 -- -- -- 150 75 

4-21-2000 2323 75 -- -- -- 155 55 

4-22-2000 0008 52 -- -- -- 128 45 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 739-02 (oil-grit separator outflow)—Continued

4-22-2000 0029 50 -- -- -- 116 40 

4-22-2000 0047 49 -- -- -- 107 38 

4-22-2000 0111 81 -- -- -- 65 55 

4-22-2000 0129 75 -- -- -- 116 50 

4-22-2000 0149 75 -- -- -- 95 50 

4-22-2000 0206 68 -- -- -- 105 40 

4-22-2000 0231 44 -- -- -- 84 30 

4-22-2000 0252 41 -- -- -- 83 28 

4-22-2000 0312 37 -- -- -- 88 27 

4-22-2000 0533 29 -- -- -- 262 29 

4-26-2000 0350 -- -- -- -- -- -- 

4-26-2000 0402 15 -- -- -- 336 24 

4-26-2000 0411 13 -- -- -- 338 24 

4-26-2000 0420 12 -- -- -- 342 21 

4-26-2000 0428 15 -- -- -- 350 23 

4-26-2000 0443 15 -- -- -- 380 24 

4-26-2000 0601 128 -- -- -- 818 140 

4-26-2000 0756 115 -- -- -- 614 140 

4-26-2000 0808 111 -- -- -- 587 130 

4-26-2000 0820 110 -- -- -- 585 130 

4-26-2000 0832 109 -- -- -- 577 140 

4-26-2000 0845 107 -- -- -- 577 140 

4-26-2000 0922 97 -- -- -- 572 130 

4-26-2000 1024 102 -- -- -- 578 140 

4-26-2000 1040 107 -- -- -- 572 150 

4-26-2000 1104 109 -- -- -- 573 130 

4-26-2000 2103 118 -- -- -- 440 150 

4-26-2000 2129 90 -- -- -- 421 140 

4-26-2000 2211 93 -- -- -- 406 130 

5-02-2000 0752 -- -- -- -- 410 110 

5-02-2000 0844 99 -- -- -- 695 120 

5-02-2000 0850 185 -- -- -- 732 140 

5-02-2000 0857 185 -- -- -- 762 150 

5-02-2000 0905 206 -- -- -- 764 150 

5-02-2000 0932 192 -- -- -- 797 140 

5-08-2000 1705 125 -- -- -- 1,010 36 

5-08-2000 1724 463 -- -- -- 1,330 230 

5-08-2000 1817 471 -- -- -- 1,640 250 

5-08-2000 1848 425 -- -- -- 1,680 230 

5-08-2000 1854 436 -- -- -- 1,690 220 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 739-02 (oil-grit separator outflow)—Continued

5-08-2000 1923 706 -- -- -- 1,680 220 

5-08-2000 2001 295 -- -- -- 961 200 

5-08-2000 2048 -- -- -- -- -- -- 

5-10-2000 1506 -- -- -- -- -- -- 

5-10-2000 1535 273 -- -- -- 909 190 

5-10-2000 1607 233 -- -- -- 901 160 

5-10-2000 2027 989 -- -- -- -- -- 

5-10-2000 2030 -- -- -- -- 335 450 

5-10-2000 2048 264 -- -- -- -- -- 

5-10-2000 2212 -- -- -- -- 432 160 

5-10-2000 2227 305 -- -- -- -- -- 

5-10-2000 2229 -- -- -- -- 216 160 

5-10-2000 2234 129 -- -- -- -- -- 

5-10-2000 2311 -- -- -- -- 181 95 

5-11-2000 0019 61 -- -- -- -- -- 

5-11-2000 0130 -- -- -- -- 186 65 

5-11-2000 0201 55 -- -- -- -- -- 

5-11-2000 0221 -- -- -- -- 191 55 

5-14-2000 0024 77 -- -- -- 506 55 

5-14-2000 0235 35 -- -- -- 372 28 

5-18-2000 1856 -- -- -- -- 419 -- 

5-18-2000 1928 152 -- -- -- 614 80 

5-18-2000 2007 190 -- -- -- 747 100 

5-18-2000 2014 176 -- -- -- 764 100 

5-18-2000 2021 183 -- -- -- 772 100 

5-18-2000 2044 181 -- -- -- 798 100 

5-18-2000 2119 157 -- -- -- 820 80 

5-20-2000 0835 177 -- -- -- 652 110 

5-20-2000 0912 170 -- -- -- 618 110 

5-20-2000 0935 156 -- -- -- 603 110 

5-20-2000 1010 144 -- -- -- 592 100 

5-20-2000 1215 134 -- -- -- 569 95 

5-20-2000 1239 137 -- -- -- 565 100 

5-20-2000 1259 126 -- -- -- 563 100 

5-20-2000 1323 130 -- -- -- 560 95 

5-20-2000 1344 130 -- -- -- 558 100 

5-20-2000 1513 128 -- -- -- 523 110 

5-20-2000 1551 136 -- -- -- 499 120 

5-20-2000 1638 119 -- -- -- 483 120 

5-24-2000 0240 74 -- -- -- 232 50 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 739-02 (oil-grit separator outflow)—Continued

5-24-2000 0414 62 -- -- -- 236 50 

5-25-2000 0137 52 -- -- -- 284 35 

5-25-2000 0158 55 -- -- -- 302 34 

5-25-2000 0226 64 -- -- -- 328 35 

5-25-2000 0813 100 -- -- -- 198 75 

5-25-2000 1018 84 -- -- -- 170 80 

5-25-2000 1144 96 -- -- -- 190 95 

5-25-2000 1207 90 -- -- -- 196 100 

5-25-2000 2201 102 -- -- -- 311 80 

5-25-2000 2223 108 -- -- -- 331 80 

5-25-2000 2254 104 -- -- -- 351 85 

5-25-2000 1039 168 -- -- -- 424 110 

5-25-2000 1101 174 -- -- -- 433 130 

5-25-2000 1131 167 -- -- -- 444 120 

6-06-2000 11148 83 -- -- -- 385 -- 

6-06-2000 11345 120 -- -- -- 99 -- 

6-06-2000 11525 86 -- -- -- 72 -- 

6-06-2000 12113 31 -- -- -- 92 -- 

6-07-2000 11016 34 -- -- -- 236 -- 

Monitoring location 739-03 (oil-grit separator inflow)

8-21-1999 2203 1,340 -- -- -- 448 63 

8-21-1999 2210 178 -- -- -- 448 37 

8-21-1999 2216 82 -- -- -- 415 52 

8-21-1999 2223 71 -- -- -- 417 51 

8-21-1999 2229 78 -- -- -- 403 46 

8-21-1999 2236 201 -- -- -- 401 50 

8-21-1999 2249 280 -- -- -- 403 47 

8-21-1999 2302 94 -- -- -- 382 42 

8-21-1999 2315 42 -- -- -- 377 39 

8-21-1999 2328 43 -- -- -- 387 37 

8-21-1999 2341 46 -- -- -- 403 42 

8-21-1999 2354 46 -- -- -- 414 43 

8-22-1999 0212 29 -- -- -- 377 24 

8-22-1999 0235 41 -- -- -- 395 31 

8-22-1999 0257 -- -- -- -- 422 33 

8-22-1999 0824 28 -- -- -- 377 21 

8-27-1999 1600 925 -- -- -- 486 210 

8-27-1999 1647 245 -- -- -- 622 80 

9-06-1999 1149 6,140 -- -- -- 534 150 

9-06-1999 1206 619 -- -- -- 342 95 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 739-03 (oil-grit separator inflow)—Continued

9-07-1999 0228 475 -- -- -- 245 75 

9-07-1999 0237 761 -- -- -- 189 65 

9-07-1999 0401 1,620 -- -- -- 170 50 

9-07-1999 0415 4,240 -- -- -- 876 70 

9-08-1999 1014 -- -- -- -- -- -- 

9-08-1999 1021 623 -- -- -- 856 110 

9-08-1999 1056 -- -- -- -- -- -- 

9-10-1999 0815 -- -- -- -- -- -- 

9-10-1999 0816 2,080 -- -- -- 223 85 

9-10-1999 0822 -- -- -- -- -- -- 

9-10-1999 0823 3,070 -- -- -- 152 120 

9-10-1999 0838 -- -- -- -- -- -- 

9-10-1999 0851 728 -- -- -- 113 80 

9-10-1999 0941 96 -- -- -- 162 90 

9-10-1999 0956 -- -- -- -- -- -- 

9-10-1999 1504 1,670 -- -- -- 142 110 

9-10-1999 1535 -- -- -- -- -- -- 

9-10-1999 1536 896 -- -- -- 93 70 

9-10-1999 1629 -- -- -- -- -- -- 

9-10-1999 1631 920 -- -- -- 89 50 

9-10-1999 1726 -- -- -- -- -- -- 

9-10-1999 1736 130 -- -- -- 70 36 

9-10-1999 1744 276 -- -- -- 62 55 

9-10-1999 1805 317 -- -- -- 43 27 

9-10-1999 1833 270 -- -- -- 45 60 

9-10-1999 1837 -- -- -- -- -- -- 

9-10-1999 1844 479 -- -- -- 36 45 

9-10-1999 1855 -- -- -- -- -- -- 

9-10-1999 1905 200 -- -- -- 41 37 

9-10-1999 1939 164 -- -- -- 40 30 

9-10-1999 1950 -- -- -- -- -- -- 

9-10-1999 2010 170 -- -- -- 38 45 

9-10-1999 2012 -- -- -- -- -- -- 

9-10-1999 2021 -- -- -- -- -- -- 

9-10-1999 2034 40 -- -- -- 32 22 

9-10-1999 2052 -- -- -- -- -- -- 

9-10-1999 2100 34 -- -- -- 31 21 

9-10-1999 2119 781 -- -- -- 34 55 

9-10-1999 2137 315 -- -- -- 27 31 

9-10-1999 2138 -- -- -- -- -- -- 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 739-03 (oil-grit separator inflow)—Continued

9-10-1999 2144 64 -- -- -- 21 23 

9-10-1999 2145 -- -- -- -- -- -- 

9-10-1999 2153 163 -- -- -- 23 19 

9-10-1999 2159 266 -- -- -- 29 31 

9-15-1999 1910 -- -- -- -- -- -- 

9-15-1999 1946 207 -- -- -- 293 210 

9-15-1999 1947 -- -- -- -- -- -- 

9-15-1999 2009 597 -- -- -- 262 100 

9-15-1999 2011 -- -- -- -- -- -- 

9-15-1999 2040 210 -- -- -- 189 95 

9-15-1999 2041 -- -- -- -- -- -- 

9-15-1999 2102 153 -- -- -- 151 90 

9-15-1999 2111 -- -- -- -- -- -- 

9-15-1999 2136 151 -- -- -- 113 75 

9-15-1999 2139 -- -- -- -- -- -- 

9-15-1999 2211 81 -- -- -- 95 60 

9-15-1999 2316 -- -- -- -- -- -- 

9-15-1999 2331 83 -- -- -- 121 55 

9-15-1999 2355 -- -- -- -- -- -- 

9-16-1999 0008 134 -- -- -- 89 55 

9-16-1999 0026 -- -- -- -- -- -- 

9-16-1999 0032 66 -- -- -- 61 50 

9-16-1999 0045 -- -- -- -- -- -- 

9-16-1999 0049 269 -- -- -- 52 40 

9-16-1999 0103 -- -- -- -- -- -- 

9-16-1999 0111 34 -- -- -- 49 32 

9-16-1999 0635 -- -- -- -- -- -- 

9-16-1999 0658 52 -- -- -- 157 55 

9-16-1999 0826 -- -- -- -- -- -- 

9-16-1999 0837 64 -- -- -- 161 85 

9-16-1999 0859 -- -- -- -- -- -- 

9-16-1999 0906 221 -- -- -- 108 90 

9-16-1999 0928 -- -- -- -- -- -- 

9-16-1999 0929 117 -- -- -- 71 75 

9-16-1999 0939 107 -- -- -- 58 80 

9-16-1999 1013 88 -- -- -- 39 65 

9-16-1999 1158 40 -- -- -- 90 50 

9-16-1999 1204 -- -- -- -- -- -- 

9-16-1999 1414 80 -- -- -- 79 60 

9-16-1999 1417 -- -- -- -- -- -- 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 739-03 (oil-grit separator inflow)—Continued

9-16-1999 1519 276 -- -- -- 56 45 

9-16-1999 1532 111 -- -- -- 44 32 

9-16-1999 1538 -- -- -- -- -- -- 

9-16-1999 1550 -- -- -- -- -- -- 

9-16-1999 1556 -- -- -- -- -- -- 

9-16-1999 1605 -- -- -- -- -- -- 

9-16-1999 1612 -- -- -- -- -- -- 

9-16-1999 1639 -- -- -- -- -- -- 

9-16-1999 1651 -- -- -- -- -- -- 

9-22-1999 2332 -- -- -- -- -- -- 

9-22-1999 2333 181 -- -- -- 297 140 

9-22-1999 2335 172 -- -- -- 309 160 

9-22-1999 2336 173 -- -- -- 312 170 

9-22-1999 2338 185 -- -- -- 310 170 

9-22-1999 2339 183 -- -- -- 305 170 

9-22-1999 2340 188 -- -- -- 301 190 

9-22-1999 2341 188 -- -- -- 298 190 

9-22-1999 2342 194 -- -- -- 294 190 

9-22-1999 2344 204 -- -- -- 295 190 

9-22-1999 2345 193 -- -- -- 296 190 

9-22-1999 2346 194 -- -- -- 296 200 

9-22-1999 2347 211 -- -- -- 301 210 

9-22-1999 2348 199 -- -- -- 308 200 

9-22-1999 2349 180 -- -- -- 316 180 

9-22-1999 2350 179 -- -- -- 324 160 

9-22-1999 2352 179 -- -- -- 327 160 

9-22-1999 2353 156 -- -- -- 332 130 

9-22-1999 2354 150 -- -- -- 331 140 

9-22-1999 2355 139 -- -- -- 329 130 

9-22-1999 2356 149 -- -- -- 327 140 

9-22-1999 2357 130 -- -- -- 327 120 

9-22-1999 2358 131 -- -- -- 324 120 

9-22-1999 2359 127 -- -- -- 326 120 

9-23-1999 0001 128 -- -- -- 325 110 

10-09-1999 0800 130 -- -- -- 412 50 

10-10-1999 1415 90 -- -- -- 260 36 

10-10-1999 1423 -- -- -- -- -- -- 

10-10-1999 1449 82 -- -- -- 207 36 

10-10-1999 1458 -- -- -- -- -- -- 

10-10-1999 1524 45 -- -- -- 203 35 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 739-03 (oil-grit separator inflow)—Continued

10-10-1999 1544 -- -- -- -- -- -- 

10-10-1999 1603 -- -- -- -- -- -- 

10-10-1999 1612 -- -- -- -- -- -- 

10-10-1999 1621 -- -- -- -- -- -- 

10-10-1999 1630 -- -- -- -- -- -- 

10-10-1999 1639 -- -- -- -- -- -- 

10-10-1999 1648 -- -- -- -- -- -- 

10-10-1999 1657 -- -- -- -- -- -- 

10-10-1999 1706 -- -- -- -- -- -- 

10-10-1999 1715 -- -- -- -- -- -- 

10-10-1999 1724 -- -- -- -- -- -- 

10-10-1999 1733 -- -- -- -- -- -- 

10-10-1999 1742 -- -- -- -- -- -- 

10-10-1999 1800 40 -- -- -- 203 31 

10-10-1999 1801 -- -- -- -- -- -- 

10-13-1999 2255 36 -- -- -- 199 31 

10-13-1999 2258 38 -- -- -- 189 31 

10-13-1999 2300 38 -- -- -- 193 27 

10-13-1999 2302 35 -- -- -- 198 28 

10-13-1999 2303 32 -- -- -- 204 27 

10-13-1999 2304 33 -- -- -- 199 28 

10-13-1999 2306 29 -- -- -- 190 24 

10-13-1999 2308 34 -- -- -- 207 23 

10-13-1999 2310 -- -- -- -- 220 22 

10-13-1999 2312 29 -- -- -- 84 109 

10-13-1999 2324 -- -- -- -- -- -- 

10-14-1999 0702 -- -- -- -- -- -- 

10-14-1999 1102 -- -- -- -- -- -- 

10-18-1999 0042 537 -- -- -- 46 75 

10-18-1999 0054 495 -- -- -- 41 65 

10-18-1999 0117 156 -- -- -- 38 50 

10-18-1999 0150 65 -- -- -- 35 35 

10-18-1999 0219 115 -- -- -- 179 90 

10-18-1999 0248 156 -- -- -- 170 120 

10-20-1999 0809 192 -- -- -- 201 220 

10-20-1999 0843 120 -- -- -- 197 130 

10-20-1999 0856 131 -- -- -- 158 140 

10-20-1999 0909 121 -- -- -- 142 140 

10-20-1999 0928 124 -- -- -- 148 150 

10-20-1999 0929 -- -- -- -- -- -- 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 739-03 (oil-grit separator inflow)—Continued

10-20-1999 1107 100 -- -- -- 161 130 

10-20-1999 1201 339 -- -- -- 147 160 

10-20-1999 1205 -- -- -- -- -- -- 

10-20-1999 1208 244 -- -- -- 102 160 

10-20-1999 1211 -- -- -- -- -- -- 

10-20-1999 1216 324 -- -- -- 86 150 

10-20-1999 1220 -- -- -- -- -- -- 

10-20-1999 1226 176 -- -- -- 75 130 

10-20-1999 1231 -- -- -- -- -- -- 

10-20-1999 1236 218 -- -- -- 64 120 

10-20-1999 1240 -- -- -- -- -- -- 

10-20-1999 1245 135 -- -- -- 59 110 

10-20-1999 1250 -- -- -- -- -- -- 

10-20-1999 1256 111 -- -- -- 56 95 

10-20-1999 1303 -- -- -- -- -- -- 

10-20-1999 1311 134 -- -- -- 57 85 

10-20-1999 1319 -- -- -- -- -- -- 

10-20-1999 1325 123 -- -- -- 57 95 

10-20-1999 1331 -- -- -- -- -- -- 

10-20-1999 1336 108 -- -- -- 54 85 

10-20-1999 1344 -- -- -- -- -- -- 

10-20-1999 1407 83 -- -- -- 54 60 

10-20-1999 1420 -- -- -- -- -- -- 

10-20-1999 1504 61 -- -- -- 78 75 

10-20-1999 1523 -- -- -- -- -- -- 

10-20-1999 1649 45 -- -- -- 103 55 

10-20-1999 1801 -- -- -- -- -- -- 

10-20-1999 1805 44 -- -- -- 131 55 

10-20-1999 1817 41 -- -- -- 134 45 

10-20-1999 1829 40 -- -- -- 135 45 

10-20-1999 1841 42 -- -- -- 136 50 

10-23-1999 0152 79 -- -- -- 154 55 

10-23-1999 0207 157 -- -- -- 173 80 

10-23-1999 0220 201 -- -- -- 166 60 

10-23-1999 0239 157 -- -- -- 162 55 

10-23-1999 0257 132 -- -- -- 155 60 

10-23-1999 0325 238 -- -- -- 123 55 

10-23-1999 0342 403 -- -- -- 97 55 

10-23-1999 0354 1,190 -- -- -- 78 55 

10-23-1999 0411 815 -- -- -- 65 45 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 739-03 (oil-grit separator inflow)—Continued

10-23-1999 0427 983 -- -- -- 57 39 

10-23-1999 0502 -- -- -- -- 61 31 

10-23-1999 0528 61 -- -- -- 70 35 

10-23-1999 0535 28 -- -- -- 71 33 

10-23-1999 0544 33 -- -- -- 72 34 

10-23-1999 0556 28 -- -- -- 73 33 

10-23-1999 0628 -- -- -- -- 78 45 

10-23-1999 0644 49 -- -- -- 83 45 

10-23-1999 0657 47 -- -- -- 94 45 

10-23-1999 0711 63 -- -- -- 107 37 

10-23-1999 0730 22 -- -- -- 119 29 

11-02-1999 2343 64 7.28 92.72 -- 307 70 

11-03-1999 0001 161 24.65 75.35 -- 329 130 

11-03-1999 0020 221 20.95 79.05 -- 342 160 

11-03-1999 0036 172 23.34 76.66 -- 286 160 

11-03-1999 0112 169 24.46 75.54 -- 247 160 

11-03-1999 0131 123 21.08 78.92 -- 200 120 

11-03-1999 0142 234 56.29 43.71 -- 151 100 

11-03-1999 0152 285 68.3 31.7 -- 116 90 

11-03-1999 0203 436 80.96 19.04 -- 94 80 

11-03-1999 0213 334 78.9 21.1 -- 79 70 

11-03-1999 0224 134 52.71 47.29 -- 73 65 

11-03-1999 0239 88 40.26 59.74 -- 64 50 

11-03-1999 0255 77 30.83 69.17 -- 67 50 

11-03-1999 0309 75 51.58 48.42 -- 67 45 

11-03-1999 0325 163 73.99 26.01 -- 68 40 

11-03-1999 0359 106 66.85 33.15 -- 69 38 

11-03-1999 0418 80 36.53 63.47 -- 76 45 

11-03-1999 0455 179 79.61 20.39 -- 58 36 

11-03-1999 0613 41 21.23 78.77 -- 58 33 

11-03-1999 0737 77 46.25 53.75 -- 84 50 

11-03-1999 0810 154 73.46 26.54 -- 102 65 

11-03-1999 0829 87 52.08 47.92 -- 112 65 

11-10-1999 2314 59 -- -- -- 116 60 

11-12-1999 2318 140 -- -- -- 224 130 

11-12-1999 2343 180 -- -- -- 227 110 

11-14-1999 1743 98 -- -- -- 286 70 

12-15-1999 0310 165 -- -- -- 340 150 

12-15-1999 0504 116 -- -- -- 213 100 

12-15-1999 0550 128 -- -- -- 154 140 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 739-03 (oil-grit separator inflow)—Continued

12-21-1999 10057 172 -- -- -- 309 150 

1-10-2000 1900 91 -- -- -- 431 24 

1-10-2000 1919 47 -- -- -- 554 25 

1-10-2000 1959 59 -- -- -- 673 26 

1-10-2000 2028 63 -- -- -- 684 32 

1-10-2000 2031 71 -- -- -- 691 32 

1-10-2000 2034 69 -- -- -- 693 37 

1-10-2000 2038 60 -- -- -- 704 25 

1-10-2000 2041 62 -- -- -- 722 22 

1-10-2000 2045 62 -- -- -- 738 24 

1-10-2000 2049 62 -- -- -- 755 25 

1-10-2000 2054 59 -- -- -- 771 28 

1-10-2000 2058 62 -- -- -- 775 20 

1-10-2000 2103 57 -- -- -- 801 22 

1-10-2000 2109 46 -- -- -- 832 23 

1-10-2000 2115 58 -- -- -- 852 26 

1-10-2000 2122 60 -- -- -- 890 27 

1-10-2000 2130 370 -- -- -- 3,390 360 

1-13-2000 1023 386 -- -- -- 3,830 360 

1-31-2000 0416 213 -- -- -- 48,800 190 

1-31-2000 0432 1,220 -- -- -- 57,200 550 

1-31-2000 0444 1,220 -- -- -- 50,900 500 

1-31-2000 0457 480 -- -- -- 38,000 500 

1-31-2000 0515 420 -- -- -- 27,100 400 

1-31-2000 0532 403 -- -- -- 20,300 400 

1-31-2000 0547 396 -- -- -- 15,300 390 

1-31-2000 0601 349 -- -- -- 12,400 500 

1-31-2000 0618 449 -- -- -- 10,700 450 

1-31-2000 0656 537 -- -- -- 9,850 360 

1-31-2000 0701 530 -- -- -- 9,950 400 

1-31-2000 0705 496 -- -- -- 10,100 600 

1-31-2000 0708 500 -- -- -- 10,300 550 

1-31-2000 0712 462 -- -- -- 10,500 550 

1-31-2000 0716 -- -- -- -- -- -- 

1-31-2000 0717 450 -- -- -- 10,600 550 

1-31-2000 0722 431 -- -- -- 10,900 550 

1-31-2000 0726 -- -- -- -- -- -- 

1-31-2000 0727 469 -- -- -- 11,000 500 

1-31-2000 0734 384 -- -- -- 11,100 500 

1-31-2000 0740 -- -- -- -- -- -- 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 739-03 (oil-grit separator inflow)—Continued

2-14-2000 0204 2,380 -- -- -- 29,700 290 

2-14-2000 0210 1,470 4.7 95.3 -- 35,100 370 

2-14-2000 0222 2,930 -- -- -- 24,700 700 

2-14-2000 0234 2,500 -- -- -- 17,500 700 

2-14-2000 0243 1,560 -- -- -- 13,100 600 

2-14-2000 0259 1,270 -- -- -- 9,410 550 

2-14-2000 0335 405 .71 99.29 -- 6,710 350 

2-14-2000 0338 1,020 -- -- -- 6,610 350 

2-14-2000 0349 1,050 -- -- -- 6,920 310 

2-14-2000 0400 984 -- -- -- 6,750 320 

2-14-2000 0404 913 -- -- -- 6,660 320 

2-14-2000 0407 888 -- -- -- 6,660 330 

2-14-2000 0411 933 -- -- -- 6,660 320 

2-14-2000 0415 795 -- -- -- 6,640 320 

2-14-2000 0420 955 -- -- -- 6,630 320 

2-14-2000 0425 350 .4 99.6 -- 6,650 320 

2-14-2000 0430 1,020 -- -- -- 6,890 340 

2-14-2000 0434 1,160 -- -- -- 7,020 360 

2-14-2000 0438 947 -- -- -- 7,060 380 

2-14-2000 0449 1,030 -- -- -- 6,870 400 

2-14-2000 0526 1,080 -- -- -- 5,560 550 

2-14-2000 0552 1,180 -- -- -- 5,030 650 

2-14-2000 0602 866 -- -- -- 4,770 750 

2-14-2000 0608 1,020 6.27 93.73 -- 4,330 900 

2-14-2000 1152 534 3.82 96.18 -- 2,220 400 

2-14-2000 1157 675 -- -- -- 2,040 400 

2-14-2000 1206 656 -- -- -- 1,760 400 

2-14-2000 1222 640 -- -- -- 1,670 400 

2-14-2000 1250 521 -- -- -- 1,820 330 

2-14-2000 1309 476 -- -- -- -- -- 

2-25-2000 1506 419 -- -- -- 21,400 450 

2-25-2000 1525 1,200 10.96 89.04 -- 14,200 1,900 

2-25-2000 1557 872 -- -- -- 7,480 1,300 

2-25-2000 1631 433 -- -- -- 5,270 800 

2-25-2000 1702 510 -- -- -- 3,720 600 

2-25-2000 1734 361 -- -- -- 3,020 400 

2-25-2000 1821 255 7.03 92.97 -- 2,840 290 

2-25-2000 1827 228 4.73 95.27 -- 2,900 270 

2-25-2000 1835 231 -- -- -- 3,030 270 

2-25-2000 1846 214 -- -- -- 3,220 260 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 739-03 (oil-grit separator inflow)—Continued

2-25-2000 1854 220 -- -- -- 3,570 260 

2-25-2000 1941 248 -- -- -- 3,340 250 

2-25-2000 2040 244 -- -- -- 2,500 280 

2-25-2000 2125 154 -- -- -- 2,590 210 

2-25-2000 2205 146 -- -- -- 2,620 190 

2-25-2000 2305 120 -- -- -- 2,180 170 

2-25-2000 2319 132 21.17 78.83 -- 2,110 160 

2-26-2000 0214 93 -- -- -- 2,890 120 

2-26-2000 0232 81 4.64 95.36 -- 2,860 120 

2-26-2000 0723 174 -- -- -- 2,840 140 

2-26-2000 0800 127 -- -- -- 2,350 160 

2-26-2000 0822 129 -- -- -- 2,260 170 

2-28-2000 0906 574 -- -- -- 4,000 550 

2-28-2000 1010 359 -- -- -- 2,920 450 

2-28-2000 1132 289 -- -- -- 2,390 380 

2-28-2000 1149 312 -- -- -- 2,370 400 

2-28-2000 1209 323 -- -- -- 2,380 400 

2-28-2000 1223 309 -- -- -- 2,390 400 

2-28-2000 1240 270 -- -- -- 2,360 360 

3-11-2000 1516 -- -- -- -- -- -- 

3-11-2000 1536 321 -- -- -- 7,300 390 

3-11-2000 1603 418 -- -- -- 6,580 550 

3-11-2000 1610 392 -- -- -- 6,220 500 

3-11-2000 1618 349 -- -- -- 5,130 450 

3-11-2000 1625 326 -- -- -- 3,810 450 

3-11-2000 1631 314 -- -- -- 3,600 400 

3-11-2000 1637 343 -- -- -- 3,450 400 

3-11-2000 1715 268 -- -- -- 3,310 380 

3-11-2000 1830 248 -- -- -- 3,150 320 

3-11-2000 1846 231 -- -- -- 3,030 300 

3-11-2000 1859 243 -- -- -- 2,690 270 

3-11-2000 1914 360 -- -- -- 2,560 200 

3-11-2000 1934 674 -- -- -- 1,950 200 

3-11-2000 2020 549 -- -- -- 1,690 190 

3-11-2000 2202 355 -- -- -- 1,180 150 

3-11-2000 2306 241 -- -- -- 801 140 

3-12-2000 0027 117 -- -- -- 608 95 

3-12-2000 0046 65 -- -- -- 756 75 

3-12-2000 0138 42 -- -- -- 685 65 

3-12-2000 0236 1,560 -- -- -- 693 65 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 739-03 (oil-grit separator inflow)—Continued

3-12-2000 0822 419 -- -- -- 1,080 75 

3-28-2000 0446 -- -- -- -- -- -- 

3-28-2000 0512 386 -- -- -- 16,400 320 

3-28-2000 0520 520 -- -- -- 20,200 450 

3-28-2000 0537 581 16.55 83.45 -- 13900 450 

3-28-2000 0554 492 -- -- -- 9,720 450 

3-28-2000 0609 500 -- -- -- 7,120 450 

3-28-2000 0622 393 9.21 90.79 -- 4,610 340 

3-28-2000 0636 352 -- -- -- 3,590 330 

3-28-2000 0651 351 -- -- -- 3,190 350 

3-28-2000 0655 362 1.11 98.89 -- 2,880 340 

3-28-2000 0659 393 -- -- -- 2,420 230 

3-28-2000 0706 683 27.22 72.78 -- 3,470 290 

3-28-2000 0719 -- -- -- -- -- -- 

3-28-2000 0732 487 -- -- -- 2,590 280 

3-28-2000 0747 456 -- -- -- 2,260 280 

3-28-2000 0831 276 1.89 98.11 -- 1,600 210 

3-28-2000 1059 220 -- -- -- 1,250 170 

3-28-2000 1122 197 -- -- -- 1,020 150 

3-28-2000 1155 126 -- -- -- 837 110 

3-29-2000 0332 104 -- -- -- 462 130 

3-29-2000 0355 87 -- -- -- 508 120 

3-29-2000 0434 88 -- -- -- 534 130 

3-29-2000 0332 -- -- -- -- -- -- 

3-29-2000 0355 -- -- -- -- -- -- 

4-04-2000 0345 132 -- -- -- 2,180 85 

4-04-2000 0359 333 -- -- -- 2,570 340 

4-04-2000 0406 258 -- -- -- 3,080 290 

4-04-2000 0417 226 -- -- -- 3,330 240 

4-04-2000 1523 2,350 -- -- -- 2,600 340 

4-04-2000 1608 379 -- -- -- 3,050 500 

4-04-2000 1729 340 -- -- -- 2,440 500 

4-04-2000 1749 296 -- -- -- 2,430 450 

4-04-2000 1816 256 -- -- -- 2,440 400 

4-08-2000 2358 302 -- -- -- 4,490 310 

4-09-2000 0005 289 -- -- -- 4,580 310 

4-09-2000 0013 250 -- -- -- 4,360 270 

4-09-2000 0022 277 -- -- -- 3,650 300 

4-09-2000 0056 169 -- -- -- 3,710 210 

4-09-2000 0119 211 -- -- -- 3,910 200 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 739-03 (oil-grit separator inflow)—Continued

4-09-2000 0146 173 -- -- -- 2,990 200 

4-09-2000 0256 122 -- -- -- 2,400 140 

4-09-2000 0406 74 -- -- -- 1,250 75 

4-09-2000 0458 181 -- -- -- 835 130 

4-09-2000 0533 113 -- -- -- 558 95 

4-09-2000 0610 109 -- -- -- 443 90 

4-09-2000 0653 85 -- -- -- 347 75 

4-09-2000 0731 170 -- -- -- 404 95 

4-09-2000 0751 107 -- -- -- 408 70 

4-09-2000 0918 42 -- -- -- 400 40 

4-09-2000 0944 36 -- -- -- 427 37 

4-09-2000 1019 39 -- -- -- 478 50 

4-11-2000 2043 166 -- -- -- 1,320 180 

4-11-2000 2113 105 -- -- -- 1,590 140 

4-11-2000 2149 84 -- -- -- 1,800 110 

4-16-2000 0817 79 -- -- -- 1,230 95 

4-16-2000 0849 88 -- -- -- 1,230 90 

4-18-2000 1834 69 -- -- -- 1,380 80 

4-18-2000 1909 169 -- -- -- 1,370 190 

4-18-2000 1957 155 -- -- -- 1,030 170 

4-18-2000 2031 142 -- -- -- 692 150 

4-18-2000 2103 129 -- -- -- 508 130 

4-18-2000 2222 72 -- -- -- 401 90 

4-19-2000 0000 50 -- -- -- 380 65 

4-19-2000 0233 24 -- -- -- 419 45 

4-19-2000 0418 26 -- -- -- 473 40 

4-19-2000 0452 39 -- -- -- 482 55 

4-19-2000 0825 97 -- -- -- 515 130 

4-19-2000 0947 106 -- -- -- 536 150 

4-19-2000 1000 105 -- -- -- 545 160 

4-19-2000 1022 97 -- -- -- 561 150 

4-21-2000 1447 73 -- -- -- 795 75 

4-21-2000 1501 178 -- -- -- 886 240 

4-21-2000 1512 199 -- -- -- 1,020 240 

4-21-2000 1522 196 -- -- -- 1,090 250 

4-21-2000 1529 187 -- -- -- 1,110 230 

4-21-2000 1840 124 -- -- -- 783 180 

4-21-2000 1958 179 -- -- -- 388 160 

4-21-2000 2015 115 -- -- -- 243 110 

4-21-2000 2131 99 -- -- -- 199 85 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 739-03 (oil-grit separator inflow)—Continued

4-21-2000 2158 82 -- -- -- 208 70 

4-21-2000 2237 142 -- -- -- 149 75 

4-21-2000 2248 98 -- -- -- 185 65 

4-21-2000 2323 66 -- -- -- 139 60 

4-22-2000 0008 52 -- -- -- 119 45 

4-22-2000 0029 54 -- -- -- 115 37 

4-22-2000 0047 53 -- -- -- 103 39 

4-22-2000 0111 105 -- -- -- 96 55 

4-22-2000 0129 99 -- -- -- 121 50 

4-22-2000 0149 96 -- -- -- 95 45 

4-22-2000 0206 71 -- -- -- 102 37 

4-22-2000 0231 54 -- -- -- 81 30 

4-22-2000 0252 46 -- -- -- 82 28 

4-22-2000 0312 36 -- -- -- 88 28 

4-22-2000 0533 41 -- -- -- 218 36 

4-26-2000 0350 25 -- -- -- 480 20 

4-26-2000 0402 44 -- -- -- 554 40 

4-26-2000 0411 52 -- -- -- 804 65 

4-26-2000 0420 58 -- -- -- 877 70 

4-26-2000 0428 75 -- -- -- 1,020 100 

4-26-2000 0443 75 -- -- -- 1,130 85 

4-26-2000 0601 153 -- -- -- 740 160 

4-26-2000 0756 100 -- -- -- 547 130 

4-26-2000 0808 87 -- -- -- 544 110 

4-26-2000 0820 57 -- -- -- 554 130 

4-26-2000 0832 94 -- -- -- 555 10 

4-26-2000 0845 96 -- -- -- 557 10 

4-26-2000 0922 142 -- -- -- 561 150 

4-26-2000 1024 127 -- -- -- 555 180 

4-26-2000 1040 118 -- -- -- 559 180 

4-26-2000 1104 117 -- -- -- 567 130 

4-26-2000 2103 88 -- -- -- 373 130 

4-26-2000 2129 75 -- -- -- 362 120 

4-26-2000 2211 76 -- -- -- 365 120 

5-02-2000 0752 63 -- -- -- 605 50 

5-02-2000 0844 153 -- -- -- 959 210 

5-02-2000 0850 160 -- -- -- 941 200 

5-02-2000 0857 166 -- -- -- 922 200 

5-02-2000 0905 167 -- -- -- 909 230 

5-02-2000 0932 164 -- -- -- 932 230 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Monitoring location 739-03 (oil-grit separator inflow)—Continued

5-08-2000 1705 1,160 -- -- -- 1,320 320 

5-08-2000 1724 607 -- -- -- 1,580 320 

5-08-2000 1817 401 -- -- -- 1,770 220 

5-08-2000 1848 415 -- -- -- 1,810 200 

5-08-2000 1854 432 -- -- -- 1,790 230 

5-08-2000 1923 1,140 -- -- -- 1,770 180 

5-08-2000 2001 209 -- -- -- 804 170 

5-08-2000 2048 -- -- -- -- -- -- 

5-10-2000 1506 -- -- -- -- -- -- 

5-10-2000 1535 222 -- -- -- 834 170 

5-10-2000 1607 212 -- -- -- 869 170 

5-10-2000 2027 -- -- -- -- -- -- 

5-10-2000 2030 2,040 -- -- -- 323 800 

5-10-2000 2048 -- -- -- -- -- -- 

5-10-2000 2212 1,380 -- -- -- 331 220 

5-10-2000 2227 -- -- -- -- -- -- 

5-10-2000 2229 527 -- -- -- 180 180 

5-10-2000 2234 -- -- -- -- -- -- 

5-10-2000 2311 218 -- -- -- 177 130 

5-11-2000 0019 -- -- -- -- -- -- 

5-11-2000 0130 150 -- -- -- 189 75 

5-11-2000 0201 -- -- -- -- -- -- 

5-11-2000 0221 75 -- -- -- 237 50 

5-14-2000 0024 107 -- -- -- 434 50 

5-14-2000 0235 75 -- -- -- 343 30 

5-18-2000 1856 114 -- -- -- 475 37 

5-18-2000 1928 261 -- -- -- 952 130 

5-18-2000 2007 216 -- -- -- 932 120 

5-18-2000 2014 202 -- -- -- 916 110 

5-18-2000 2021 220 -- -- -- 915 100 

5-18-2000 2044 176 -- -- -- 919 100 

5-18-2000 2119 209 -- -- -- 826 75 

5-20-2000 0835 167 -- -- -- 549 110 

5-20-2000 0912 136 -- -- -- 529 110 

5-20-2000 0935 141 -- -- -- 522 100 

5-20-2000 1010 139 -- -- -- 534 90 

5-20-2000 1215 130 -- -- -- 543 95 

5-20-2000 1239 109 -- -- -- 558 90 

5-20-2000 1259 113 -- -- -- 539 90 

5-20-2000 1323 115 -- -- -- 514 95 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
1Composite of two or more samples.

Monitoring location 739-03 (oil-grit separator inflow)—Continued

5-20-2000 1344 131 -- -- -- 540 110 

5-20-2000 1513 148 -- -- -- 438 140 

5-20-2000 1551 132 -- -- -- 448 130 

5-20-2000 1638 124 -- -- -- 458 120 

5-24-2000 0240 66 -- -- -- 235 44 

5-24-2000 0414 58 -- -- -- 295 35 

5-25-2000 0137 78 -- -- -- 401 50 

5-25-2000 0158 86 -- -- -- 480 50 

5-25-2000 0226 77 -- -- -- 493 37 

5-25-2000 0813 95 -- -- -- 171 70 

5-25-2000 1018 111 -- -- -- 191 95 

5-25-2000 1144 104 -- -- -- 227 95 

5-25-2000 1207 100 -- -- -- 249 100 

5-25-2000 2201 116 -- -- -- 485 75 

5-25-2000 2223 99 -- -- -- 515 60 

5-25-2000 2254 107 -- -- -- 548 55 

5-25-2000 1039 199 -- -- -- 484 160 

5-25-2000 1101 166 -- -- -- 517 120 

5-25-2000 1131 142 -- -- -- 547 95 

6-06-2000 11148 111 -- -- -- 341 -- 

6-06-2000 11345 106 -- -- -- 104 -- 

6-06-2000 11525 82 -- -- -- 77 -- 

6-06-2000 12113 29 -- -- -- 86 -- 

6-07-2000 11016 29 -- -- -- 254 -- 

Table 1A. Instantaneous discharge, specific conductance, turbidity, and concentrations and particle-size characteristic

suspended sediment in highway runoff sampled at the inlets and outlets of structural best management practices at mo

stations 136 and 739, along the Southeast Expressway, Boston, Massachusetts—Continued

Date Time

Suspended

sediment

concentration

(mg/L)

Percentage of 

coarse-grained

particles

(% > 0.062 mm)

Percentage of 

coarse-grained

particles

(% 0.062 mm to 

0.250 mm)

Percentage of 

coarse-grained

particles

(% > 0.250 mm)

Specific

conductance

(μS/cm at 

250 ̊C)

Turbidity

(ntu)

In

di
Table 1B. Suspended sediment concentrations of equipment blank samples and other quality-control samples collecte

the inlet and the outlet of structural best management practices at monitoring stations 136 and 739, along the Southea

Expressway, Boston, Massachusetts 

Station

identifier Date Time Quality-assurance 

sample type

Suspended sediment

concentration

(mg/L)

Suspended se

concentra

(% > 0.062 

136-02 2-09-2000 1440 EQ-Blank 14 --

136-02 5-03-2000 1450 EQ-Blank 2 --

136-02 5-24-2000 0938 R-Grab 51 (58) --

136-02 5-25-2000 0943 R-Grab 286 (300) --

136-02 6-12-2000 1420 EQ-Blank 0 --

136-03 6-12-2000 1450 EQ-Blank 0 --

136-04 2-09-2000 1420 EQ-Blank 176 --

136-04 5-03-2000 1500 EQ-Blank 21 --

136-04 5-24-2000 0911 R-Grab 128 (197) --

136-04 5-25-2000 0937 R-Grab 380 (396) --

136-04 5-25-2000 0948 R-Grab 377 (390) --

136-04 5-25-2000 0956 R-Grab 344 (341) --

136-04 6-12-2000 1500 EQ-Blank 0 --

136-05 6-12-2000 1500 EQ-Blank 33* --

739-02 12-21-1999 1430 EQ-Blank 0 --

739-02 2-09-2000 1250 EQ-Blank 35 --

739-02 5-03-2000 1405 EQ-Blank 12 --

739-02 6-08-2000 1200 EQ-Blank 0 --

739-03 12-21-1999 1330 EQ-Blank 12 --

739-03 2-09-2000 1300 EQ-Blank 23 --

739-03 2-25-2000 1506 R-EQ 470 (419) --

739-03 2-25-2000 1525 R-EQ 1,160 (1,200) 4 (11)

739-03 2-25-2000 1557 R-EQ 872 (872) --

739-03 2-25-2000 1631 R-EQ 640 (433) --

739-03 2-25-2000 1702 R-EQ 518 (510) --

739-03 2-25-2000 1734 R-EQ 348 (361) --

739-03 2-25-2000 1821 R-EQ 244 (255) 3 (7)

739-03 2-25-2000 1827 R-EQ 233 (228) 2 (5)

739-03 2-25-2000 1835 R-EQ 225 (231) --

739-03 2-25-2000 1846 R-EQ 211 (214) --

739-03 2-25-2000 1854 R-EQ 215 (220) --

739-03 2-25-2000 1941 R-EQ 231 (248) --

739-03 2-25-2000 2040 R-EQ 230 (244) --

739-03 2-25-2000 2125 R-EQ 152 (154) --

739-03 2-25-2000 2205 R-EQ 137 (146) --

739-03 2-25-2000 2305 R-EQ 123 (120) --

739-03 2-25-2000 2319 R-EQ 113 (132) 3 (21)

739-03 2-26-2000 0214 R-EQ 84 (93) --

739-03 2-26-2000 0232 R-EQ 78 (81) 4 (5)

739-03 2-26-2000 0723 R-EQ 125 (174) --

Table 1B. Suspended sediment concentrations of equipment blank samples and other quality-control samples collecte

the inlet and the outlet of structural best management practices at monitoring stations 136 and 739, along the Southea

Expressway, Boston, Massachusetts

[EQ, equipment; R, replicate; mg/L, milligrams per liter; mm, millimeters; %, percent; ( ), primary sample; --, no data]
1Suspected contamination.

739-03 2-26-2000 0800 R-EQ 122 (127) --

739-03 2-26-2000 0822 R-EQ 120 (129) 0.5

739-03 2-28-2000 0906 R-EQ 454 (574) --

739-03 2-28-2000 1010 R-EQ 396 (359) 8

739-03 5-03-2000 1400 EQ-Blank 5 --

739-03 6-08-2000 1200 EQ-Blank 0 --

Table 1B. Suspended sediment concentrations of equipment blank samples and other quality-control samples collecte

the inlet and the outlet of structural best management practices at monitoring stations 136 and 739, along the Southea

Expressway, Boston, Massachusetts—Continued

Station

identifier Date Time Quality-assurance sample type

Suspended sediment

concentration

(mg/L)

Suspended se

concentra

(% > 0.062 
Table 1C. Analytical results of double-blind samples analyzed at the U.S. Geological Survey Kentucky Sediment Labo

Louisville, Kentucky

[mg, milligrams; mg/L, miligrams per liter; mm, millimetes; %, percent; <,actual value is less than value shown; >,actual value is greater than valu

-, no data]

Station

identifier

Date

Actual sediment 

concentration

(mg/L)

Reported 

sediment

concentration 

(mg/L)

Relative

percent

difference

Actual

mass of

fines

(mg)

Reported

mass of

fines

(mg)

Percent

difference

fines

A

ma

s

(

136-03 1-10-2000 1,854.9 1830 1 1,149 1,118.9 -3 

739-03 6-06-2000 45.9 43.5 5 35.5 -- -- 

739-02 6-06-2000 44 41.3 6 34.3 -- -- 

136-05 5-25-2000 908.6 884.4 3 501.9 -- -- 

136-05 5-25-2000 842.8 819.8 3 498.6 -- -- 

136-05 5-25-2000 68.3 61.3 10 35.6 -- -- 

Station

identifier

Date

Reported

mass of sand

(mg)

Percent

difference

sand

Actual

percentage of

fine-grained

particles

(% < 0.062 mm)

Reported

percentage of

fine-grained

particles

(% < 0.062 mm)

Actual

percentage of

coarse-grained

particles

(% > 0.062 mm)

Repo

percen

coarse-

part

(% > 0.0

136-03 1-10-2000 153.7 3 88 88 12 1

739-03 6-06-2000 -- -- -- -- -- -

739-02 6-06-2000 -- -- -- -- -- -

136-05 5-25-2000 -- -- -- -- -- -

136-05 5-25-2000 -- -- -- -- -- -

136-05 5-25-2000 -- -- -- -- -- -
Table 1D. Experimental water-column suspended sediment 

concentration data collected from the inlet of the 1,500-

gallon off-line oil-grit separator at station 136, along the 

Southeast Expressway, Boston, Massachusetts

[mg/L, milligrams per liter; mm, millimeters; ft3/s, cubic feet per second; 

%, percent; >, actual value is greater than value shown]

Sampler

intake location

relative to

pipe floor

(in feet)

Suspended 

sediment 

concentration

(mg/L)

Suspended 

sediment

concentration

(% > 0.062 mm)

Instantaneous

discharge

(ft3/s)

0.06 1,170 96 0.13

.06 551 88 .13

.06 810 92 .13

.14 829 95 .13

.14 707 94 .13

.14 876 93 .13

.19 405 87 .13

.19 279 82 .13

.19 331 79 .13

.06 352 87 .22

.06 434 88 .22

.06 421 87 .22

.14 253 70 .22

.14 279 80 .22

.14 251 81 .22

.19 203 74 .22

.19 233 81 .22

.19 243 79 .22

.06 2,150 92 .45

.06 1,280 86 .45

.06 1,740 93 .45

.19 732 73 .45

.19 724 63 .45

.19 798 85 .45

.29 755 83 .45

.29 718 78 .45

.29 857 87 .45
Table 1E. Particle-size distribution of pavement-sweeping 

samples collected along the Southeast Expressway, Boston, 

Massachusetts

[<, actual value is less than values shown; >,actual value is greater than 

values shown]

Particle size

diameter

(millimeters)

Percentage of particles

sample collection date

6-15-1999 3-17-2000 6-15-2000

>16 0 0 0

8>16 3 6 0

4>8 2 4 2

2>4 1 9 3

1>2 3 15 9

0.5>1 8 28 25

0.250>0.5 26 21 29

0.125>0.25 34 8 16

0.062>0.125 15 2 6

<.062 8 7 10
[<, actual value is less than values shown; >,actual value is greater than values shown]

Station

Identifier

Date Sample 

location

Percentage of particles-size fraction, in millimeters

>16 8>16 4>8 2>4 1>2 0.5>1 0.250>0.5 0.125>0.25 0.062>0.125 <0.062

136-01 12-23-1999 composite of both chambers 0 1 1 5 10 25 35 17 3 3

739-01 12-23-1999 0 1 4 4 10 26 35 13 2 5

749-01 1-19-2000 0 0 1 1 5 25 33 13 3 18

136-01 6-12-2000 primary chamber 0 1 2 5 10 18 33 18 4 8

136-01 6-12-2000 secondary chamber 0 0 2 3 3 3 14 20 12 44

739-01 6-08-2000 primary chamber 0 0 1 7 13 31 26 8 2 12

739-01 6-08-2000 secondary chamber 0 0 1 2 4 8 18 20 7 39

749-01 6-08-2000 primary chamber 0 0 2 3 5 12 34 28 5 12

749-01 6-08-2000 secondary chamber 0 0 1 2 2 5 18 24 9 39

136-06 6-14-2000 sump 0 0 11 10 17 25 21 7 2 7
[E, estimated; -LR, laboratory replicate sample; -R, replicate sample; USEPA, United States Environmental Protection Agency; XRAL, XRAL Laboratory; ppm, parts per million; ppb, parts per billion; <, 

concentration is less than value shown; >, concentration is greater than value shown; --, no data; mm, millimeters]

Station 

identifier Date

Inorganic

analysis

method

Calcium

(ppm)

Magnesium

(ppm)

Sodium

(ppm)

Potassium

(ppm)

Phosphorus

total

(ppm as P)

Carbon, 

inorganic

total

(ppm)

Aluminum

(ppm)

Antimony

(ppm)

Arsenic

(ppm)

Barium

(ppm)

3-Station 

composite 11-25-1998 USEPA 3050B 3,100 2,000 200 600 400 12,000 4,400 <5 <3 48

136-01 12-23-1999 USEPA 3050B 6,200 7,000 600 3,200 1,300 112,000 16,200 <5 4 228

136-01-LR 12-23-1999 USEPA 3050B 5,900 6,600 600 2,900 1,200 110,000 15,500 <5 4 206

136-01 12-23-1999 USEPA 3050B 2,500 1,300 400 800 >100 15,200 3,200 <5 <3 54

136-01-R 12-23-1999 USEPA 3050B 2,400 1,300 400 900 >100 9,900 3,400 <5 <3 44

136-01 12-23-1999 XRAL ICP70 2,400 1,400 500 1,000 300 5,800 3,500 <5 <3 40

136-01 12-23-1999 -- -- -- -- -- -- -- -- -- -- --

136-01 12-23-1999 USEPA 3050B 7,900 2,100 5,900 1,100 500 191,000 4,300 <5 3 238

136-01-R 12-23-1999 -- -- -- -- -- -- -- -- -- -- --

739-01 12-23-1999 USEPA 3050B 6,200 8,400 300 4,400 600 111,000 20,500 <5 3 344

739-01 12-23-1999 XRAL ICP70 6,300 9,900 600 4,300 1,200 113,000 21,200 18 8 373

739-01 12-23-1999 USEPA 3050B 2,800 1,100 >100 800 >100 8,100 2,900 <5 <3 36

739-01-LR 12-23-1999 USEPA 3050B 3,200 1,300 900 1,000 200 30,200 3,300 <5 <3 64

739-01-R 12-23-1999 USEPA 3050B 3,500 1,100 >100 1,000 >100 17,400 3,100 <5 <3 59

739-01 12-23-1999 XRAL ICP70 3,500 1,300 500 1,100 200 11,800 3,300 <5 <3 40

739-01 12-23-1999 -- -- -- -- -- -- -- -- -- -- --

739-01 12-23-1999 USEPA 3050B 7,700 1,900 2,200 1,600 >100 127,000 4,800 <5 <3 81

749-01 12-23-1999 USEPA 3050B 8,500 10,200 5,100 4,100 200 133,000 19,700 <5 6 345

749-01 1-19-2000 XRAL ICP70 8,600 11,400 5,600 3,800 1,100 132,000 18,900 16 7 357

749-01 1-19-2000 USEPA 3050B 3,200 1,200 200 900 >100 30,900 3,200 <5 <3 62

749-01 1-19-2000 XRAL ICP70 3,600 1,500 700 1,000 300 39,500 3,600 <5 <3 68

749-01-R 1-19-2000 XRAL ICP70 3,700 1,500 700 1,000 300 43,600 3,500 <5 <3 71

749-01 1-19-2000 -- -- -- -- -- -- -- -- -- -- --

749-01 1-19-2000 USEPA 3050B 7,000 1,300 20,100 700 1,000 377,000 6,500 <5 11 134
Station 

identifier Date Beryllium

(ppm)

Bismuth

(ppm)

Cadmium

(ppm)

Chromium

(ppm)

Cobalt

(ppm)

Copper

(ppm)

Iron

(ppm)

Lanthanum

(ppm)

Lead

(ppm)

Manganese

(ppm)

Mercury

(ppm)

Molybdenum

(ppm)

3-Station 

composite 11-25-1998 <.5 <5 <1 62 <1 100 19,500 8.9 84 2,000 <1 1

136-01 12-23-1999 1 <5 7 196 13 710 54,200 23.2 438 531 <1 15

136-01-LR 12-23-1999 .9 <5 7 186 13 667 51,700 23.6 419 505 <1 14

136-01 12-23-1999 <.5 <5 <1 281 3 61.4 20,800 8 47 204 <1 6

136-01-R 12-23-1999 <.5 <5 <1 389 4 73.1 23,700 8.5 41 207 <1 7

136-01 12-23-1999 <.5 <5 <1 481 7 66.6 21,200 8.9 53 257 -- 8

136-01 12-23-1999 -- -- -- -- -- -- -- -- -- -- -- --

136-01 12-23-1999 <.5 <5 <1 297 5 52.3 16,700 10.6 67 370 <1 7

136-01-R 12-23-1999 -- -- -- -- -- -- -- -- -- -- -- --

739-01 12-23-1999 1.1 <5 5 196 14 470 46,500 26.2 308 569 <1 11

739-01 12-23-1999 .6 <5 4 228 18 515 43,600 28.8 339 699 -- 14

739-01 12-23-1999 <.5 <5 <1 348 4 81.6 22,200 10.1 36 203 <1 6

739-01-LR 12-23-1999 <.5 <5 <1 468 3 79 19,200 7.7 65 188 <1 9

739-01-R 12-23-1999 <.5 <5 <1 379 4 52.8 22,300 9.3 37 216 <1 8

739-01 12-23-1999 <.5 <5 <1 518 8 77.1 20,400 9.6 35 251 -- 9

739-01 12-23-1999 -- -- -- -- -- -- -- -- -- -- -- --

739-01 12-23-1999 <.5 <5 <1 407 5 27.1 14,700 10.7 60 257 <1 13

749-01 12-23-1999 1.1 <5 7 163 13 493 40,000 24.6 350 508 <1 12

749-01 1-19-2000 .6 <5 7 200 15 502 34,900 24.3 359 584 -- 14

749-01 1-19-2000 <.5 <5 <1 459 3 70.5 18,800 7.7 63 185 <1 9

749-01 1-19-2000 <.5 <5 1 491 6 90.4 17,400 7.8 108 233 -- 10

749-01-R 1-19-2000 <.5 <5 <1 483 5 87 16,700 8.6 86 220 -- 11

749-01 1-19-2000 -- -- -- -- -- -- -- -- -- -- -- --

749-01 1-19-2000 <.5 <5 2 373 4 89.1 16,200 5 86 117 <1 11
Station 

identifier Date Nickel

(ppm)

Scandium

(ppm)

Silver

(ppm)

Strontium

(ppm)

Tin

(ppm)

Titanium

(ppm)

Tungsten

(ppm)

Vanadium

(ppm)

Yttrium

(ppm)

Zinc

(ppm)

Zirconium

(ppm)

3-Station 

composite 11-25-1998 15 0.8 <.2 12.6 <10 300 <10 19 4.1 328 3.2

136-01 12-23-1999 85 3.2 0.8 30.6 <10 1,000 <10 70 12.1 2,200 13.8

136-01-LR 12-23-1999 79 2.9 .9 28.9 <10 900 <10 66 11.2 2,060 12.8

136-01 12-23-1999 26 .6 <.2 13.7 <10 300 <10 15 3.7 218 5.4

136-01-R 12-23-1999 32 .7 <.2 13.6 <10 300 <10 18 4.2 203 5.8

136-01 12-23-1999 37 .6 <.2 13.1 <10 300 <10 18 4.3 170 7.1

136-01 12-23-1999 -- -- -- -- -- -- -- -- -- -- --

136-01 12-23-1999 72 .8 <.2 31.8 <10 400 <10 18 6.7 464 8.6

136-01-R 12-23-1999 -- -- -- -- -- -- -- -- -- -- --

739-01 12-23-1999 66 4.1 .3 49.5 <10 1,100 <10 76 13.4 1,800 17.8

739-01 12-23-1999 71 3.9 .8 51.4 21 800 <10 84 13.9 1,930 16.7

739-01 12-23-1999 27 .5 <.2 13.7 <10 200 <10 15 4.4 200 5.5

739-01-LR 12-23-1999 39 .6 <.2 20.5 <10 200 <10 18 4.2 300 6.4

739-01-R 12-23-1999 32 .5 <.2 15.9 <10 200 <10 16 4.7 242 6

739-01 12-23-1999 36 .5 <.2 16.7 <10 200 <10 18 4.9 178 7.2

739-01 12-23-1999 -- -- -- -- -- -- -- -- -- -- --

739-01 12-23-1999 35 1 <.2 31.8 <10 400 <10 15 8.2 244 8.8

749-01 12-23-1999 57 3.9 <.2 71.4 <10 1,000 <10 77 12.8 2,010 16.6

749-01 1-19-2000 57 3.5 .8 73.6 20 700 <10 80 12.9 2,060 14.4

749-01 1-19-2000 42 .6 <.2 19.7 <10 200 <10 17 4.1 306 6

749-01 1-19-2000 42 <.5 <.2 20.2 <10 200 <10 21 4.1 399 5.5

749-01-R 1-19-2000 37 <.5 <.2 22.4 <10 200 <10 20 4.2 369 5.1

749-01 1-19-2000 -- -- -- -- -- -- -- -- -- -- --

749-01 1-19-2000 46 <.5 1 56.3 255 200 <10 22 2.7 637 7.1
Station 

identifier Date

Sediment 

size

fraction

(in mm)

Percentage of

fine-grained

particles

(percent 

>0.062 mm)

Polychlorinated

byphenols,

total

(ppb)

4Hcypenphenanthrene

(ppb)

9HFluorene,

1Methyl

(ppb)

9HFluorene

(ppb)

Acenaphthene

(ppb)

Acenaphthylene

(ppb)

Anthracene,

2-Methyl

(ppb)

Anthracene

(ppb)

Benz (A)

anthracene

(ppb)

3-Station 

composite 11-25-1998 <2.00 -- 67 150 <50 142 93.8 <50 -- 232 610

136-01 12-23-1999 <0.062 -- -- -- -- -- -- -- -- -- --

136-01-LR 12-23-1999 <0.062 -- -- -- -- -- -- -- -- -- --

136-01 12-23-1999 0.062 >2.00 100 -- -- -- -- -- -- -- -- --

136-01-R 12-23-1999 0.062 >2.00 -- -- -- -- -- -- -- -- -- --

136-01 12-23-1999 0.062 >2.00 -- -- -- -- -- -- -- -- -- --

136-01 12-23-1999 <2.00 -- 75 129 E22.1 142 127 E28.9 E33.3 259 571

136-01 12-23-1999 >2.00 -- 280 1,060 E73.6 1,390 E678 E710 E412 2,890 3,560

136-01-R 12-23-1999 >2.00 -- 320 -- -- -- -- -- -- -- --

739-01 12-23-1999 <0.062 -- -- -- -- -- -- -- -- -- --

739-01 12-23-1999 <0.062 -- -- -- -- -- -- -- -- -- --

739-01 12-23-1999 0.062 >2.00 100 -- -- -- -- -- -- -- -- --

739-01-LR 12-23-1999 0.062 >2.00 -- -- -- -- -- -- -- -- -- --

739-01-R 12-23-1999 0.062 >2.00 -- -- -- -- -- -- -- -- -- --

739-01 12-23-1999 0.062 >2.00 -- -- -- -- -- -- -- -- -- --

739-01 12-23-1999 <2.00 -- 32 E42.1 <50 E35.2 E26.9 E24.9 E10.6 70.2 221

739-01 12-23-1999 >2.00 -- 190 489 <85 713 168 413 E70.8 893 1,540

749-01 12-23-1999 <0.062 -- -- -- -- -- -- -- -- -- --

749-01 1-19-2000 <0.062 -- -- -- -- -- -- -- -- -- --

749-01 1-19-2000 0.062 >2.00 100 -- -- -- -- -- -- -- -- --

749-01 1-19-2000 0.062 >2.00 -- -- -- -- -- -- -- -- -- --

749-01-R 1-19-2000 0.062 >2.00 -- -- -- -- -- -- -- -- -- --

749-01 1-19-2000 <2.00 -- 112 E236 <250 331 272 E78.7 E45.5 415 915

749-01 1-19-2000 >2.00 -- 2,000 E1,430 E44.6 11,800 E674 E464 E1,210 29,900 5,080
Station 

identifier Date

Benzo (A)

pyrene

(ppb)

Benzo (B)

fluoranthene

(ppb)

Benzo(GHI)

perylene

(ppb)

Benzo (K)

fluoranthene

(ppb)

Chrysene

(ppb)

Dibenz (AH),

Anthracen

(ppb)

Fluoranthene

(ppb)

Indeno

123-CD

pyrene

(ppb)

Isophorone

(ppb)

Napthalene, 12

dimethl

(ppb)

Napthalene, 16

dimethl

(ppb)

3-Station 

composite 11-25-1998 611 1,080 455 335 773 70.9 1,550 -- <50 <50 <50

136-01 12-23-1999 -- -- -- -- -- -- -- -- -- -- --

136-01-LR 12-23-1999 -- -- -- -- -- -- -- -- -- -- --

136-01 12-23-1999 -- -- -- -- -- -- -- -- -- -- --

136-01-R 12-23-1999 -- -- -- -- -- -- -- -- -- -- --

136-01 12-23-1999 -- -- -- -- -- -- -- -- -- -- --

136-01 12-23-1999 599 735 E190 847 698 E69.1 1,060 E250 <50 E11.7 E28.6

136-01 12-23-1999 2,700 3,140 E587 3,610 4,060 E266 8,050 E844 <750 E143 E430

136-01-R 12-23-1999 -- -- -- -- -- -- -- -- -- -- --

739-01 12-23-1999 -- -- -- -- -- -- -- -- -- -- --

739-01 12-23-1999 -- -- -- -- -- -- -- -- -- -- --

739-01 12-23-1999 -- -- -- -- -- -- -- -- -- -- --

739-01-LR 12-23-1999 -- -- -- -- -- -- -- -- -- -- --

739-01-R 12-23-1999 -- -- -- -- -- -- -- -- -- -- --

739-01 12-23-1999 -- -- -- -- -- -- -- -- -- -- --

739-01 12-23-1999 265 238 E113 378 308 E38.2 461 E139 E14.2 E3.1 E7.2

739-01 12-23-1999 1,320 1,460 E343 1,260 1,170 E136 3,580 E430 <85 E9.6 E41.5

749-01 12-23-1999 -- -- -- -- -- -- -- -- -- -- --

749-01 1-19-2000 -- -- -- -- -- -- -- -- -- -- --

749-01 1-19-2000 -- -- -- -- -- -- -- -- -- -- --

749-01 1-19-2000 -- -- -- -- -- -- -- -- -- -- --

749-01-R 1-19-2000 -- -- -- -- -- -- -- -- -- -- --

749-01 1-19-2000 841 1,200 E332 871 1,230 E130 1,940 E417 <250 E17.1 E53.9

749-01 1-19-2000 2,790 4,370 E701 3,160 9,220 E307 13,600 E937 <1,500 E119 E213
Station 

identifier Date

Napthalene,

236 trimeth

(ppb)

Napthalene, 

26 dimethl

(ppb)

Napthalene,

2-ethyl

(ppb)

Napthalene,

(ppb)

P-Cresol

(ppb)

Phenanthrene

1methyl

(ppb)

Phenanthrene

(ppb)

Phenan-thridine

(ppb)

Pyrene,

1-methyl,

(ppb)

Pyrene,

(ppb)

3-Station 

composite 11-25-1998 <50 <50 <50 65.6 348 -- 1,230 -- 57.8 1,290

136-01 12-23-1999 -- -- -- -- -- -- -- -- -- --

136-01-LR 12-23-1999 -- -- -- -- -- -- -- -- -- --

136-01 12-23-1999 -- -- -- -- -- -- -- -- -- --

136-01-R 12-23-1999 -- -- -- -- -- -- -- -- -- --

136-01 12-23-1999 -- -- -- -- -- -- -- -- -- --

136-01 12-23-1999 E26.4 E34.1 E15.5 67.7 705 63.2 1,020 E38.9 E36.4 783

136-01 12-23-1999 E355 E490 E199 E464 1,040 E482 8,380 E240 E436 6,360

136-01-R 12-23-1999 -- -- -- -- -- -- -- -- -- --

739-01 12-23-1999 -- -- -- -- -- -- -- -- -- --

739-01 12-23-1999 -- -- -- -- -- -- -- -- -- --

739-01 12-23-1999 -- -- -- -- -- -- -- -- -- --

739-01-LR 12-23-1999 -- -- -- -- -- -- -- -- -- --

739-01-R 12-23-1999 -- -- -- -- -- -- -- -- -- --

739-01 12-23-1999 -- -- -- -- -- -- -- -- -- --

739-01 12-23-1999 E12.6 E10.7 E6.8 E25.7 161 E20.3 320 E11.5 E28.8 358

739-01 12-23-1999 E52.3 E32.2 E28.2 394 250 106 3,830 98 105 2,630

749-01 12-23-1999 -- -- -- -- -- -- -- -- -- --

749-01 1-19-2000 -- -- -- -- -- -- -- -- -- --

749-01 1-19-2000 -- -- -- -- -- -- -- -- -- --

749-01 1-19-2000 -- -- -- -- -- -- -- -- -- --

749-01-R 1-19-2000 -- -- -- -- -- -- -- -- -- --

749-01 1-19-2000 E83.3 E67 E53.6 E160 325 E93.7 2,280 E47.5 E114 1,500

749-01 1-19-2000 E447 E509 E232 E1,430 E890 E1,010 29,600 E147 E533 8510
Table 1H. Physical properties and event mean concentrations of major inorganic constituents, nutrients, trace metals, 

suspended sediments, fecal-indicator bacteria, and semi-volatile organic compounds for highway runoff event mean 

concentrations from sequential points within the drainage system of the Southeast Expressway near Boston, Massach

[ ̊C, Degrees Celsius; E, estimated; ntu, nephelometric turbidity units; -R, replicate sample; USGS-MA U.S. Geological Survey-Massachusetts; 

mg/L, milligrams per liter; μg/L, micrograms per liter; μS/cm, microsiemen per centimeter; μm, micrometers; <, concentration is less than value s

>, concentration is greater than value shown; (), laboratory rerun; fecal-indicator bacteria were mathematically estimated from subcomposites; --, n

Station

identifier Date

Specific

conductance, 

laboratory

(μS/cm at 25 ̊C)

Specific

conductance,

field

(μS/cm at 25 ̊C)

ph water

whole field

(standard

units)

Turbidity,

field

(ntu)

Oxygen

demand,

chemical

(mg/L)

Co

(co

Environmental samples

739-02 9-30-1999 161 160 7.3 160 84 

739-02-R 9-30-1999 161 160 7.3 160 79 

739-02 1-10-2000 643 632 6.6 190 93 

739-02 3-17-2000 1,050 990 7.6 75 88 

739-02 6-02-2000 402 414 6.6 130 120 

739-03 9-30-1999 149 147 7.3 170 77 

739-03-R 9-30-1999 149 147 7.3 170 77 

739-03 1-10-2000 737 735 7.9 210 93 

739-03-R 1-10-2000 740 735 7.9 210 130 

739-03 3-17-2000 4,390 4,150 7.4 110 85 

739-03 6-02-2000 368 366 6.7 160 140 

136-02 9-30-1999 242 242 7.2 140 94 

136-02 1-10-2000 829 818 7.8 230 120 

136-02-R 1-10-2000 823 821 7.8 220 120 

136-02 3-17-2000 884 834 7.2 110 67 

136-02 6-02-2000 315 312 6.8 130 42 

136-03 9-30-1999 203 193 7.1 170 37 

136-03 1-10-2000 930 922 7.7 230 130 

136-03 3-17-2000 1,030 958 7.2 120 79 

136-03 6-02-2000 325 320 6.7 130 130 

136-04 9-30-1999 195 189 7.1 250 130 

136-04 1-10-2000 1,140 1,139 7.8 300 160 

136-04 3-17-2000 457 428 7.2 110 55 

136-04 6-02-2000 269 265 6.3 190 58 

136-05 9-30-1999 122 120 7.3 280 71 

136-05 1-10-2000 879 864 7.9 320 160 

136-05 3-17-2000 302 278 7.1 110 54 

136-05-R 3-17-2000 *24 278 7.1 110 50 

136-05 6-02-2000 200 195 6.5 240 160 

Quality-control samples

Deionized water blanks

USGS-MA Laboratory 7-12-1999 1.33 -- -- -- -- 

USGS-MA Laboratory 2-08-2000 1.74 -- -- -- -- 

Ambient-atmospheric blanks

USGS-MA Laboratory 7-12-1999 <2.6 -- -- -- -- 

USGS-MA Laboratory 2-08-2000 E1.52 -- -- -- -- 

Equipment blanks

USGS-MA Laboratory 9-28-1999 E1.37 1 -- -- <10 

USGS-MA Laboratory 6-01-2000 -- -- -- -- -- 

Material blanks

USGS-MA Laboratory 7-29-1998 2 -- -- -- -- 

USGS-MA Laboratory 3-18-1999 -- 1 -- -- -- 
Table 1H. Physical properties and event mean concentrations of major inorganic constituents, nutrients, trace metals, 

suspended sediments, fecal-indicator bacteria, and semi-volatile organic compounds for highway runoff event mean 

concentrations from sequential points within the drainage system of the Southeast Expressway near Boston, Massach

Continued

Station

identifier Date

Enterococci

(col/100 

mL)

Calcium,

dissolved

(mg/L as 

Ca)

Magnesium,

dissolved

(mg/L as 

Mg)

Sodium,

dissolved

(mg/L as 

Na)

Potassium,

dissolved

(mg/L as K)

Sulfate,

dissolved

(mg/L as 

SO4)

C

di

(m

Environmental samples—Continued

739-02 9-30-1999 -- 9.6 0.6 18.0 1.6 13 

739-02-R 9-30-1999 -- 9.7 .6 18 1.6 13 

739-02 1-10-2000 -- 11 .7 100 1.5 11 

739-02 3-17-2000 -- 8.0 .8 190 1.1 9.7 

739-02 6-02-2000 -- 12 .8 61 2.1 18 

739-03 9-30-1999 8,200 -- -- -- -- -- 

739-03-R 9-30-1999 -- 8.6 .6 16 1.6 12 

739-03 1-10-2000 3,800 15 .8 120 1.8 13 

739-03-R 1-10-2000 -- 15 .8 120 1.9 13 

739-03 3-17-2000 410 20 2.3 840 2.6 21 1,

739-03 6-02-2000 2,700 11 .7 54 1.8 18 

136-02 9-30-1999 -- 13 .9 27 2.2 19 

136-02 1-10-2000 -- 14 .9 130 1.8 14 

136-02-R 1-10-2000 -- 14 .9 130 1.9 14 

136-02 3-17-2000 -- 8.5 .7 150 1.2 11 

136-02 6-02-2000 -- 10 .7 45 1.7 14 

136-03 9-30-1999 12,000 11 .8 22 1.8 17 

136-03 1-10-2000 5,900 15 1.0 160 2 15 

136-03 3-17-2000 580 10 .8 180 1.3 13 

136-03 6-02-2000 2,600 11 .7 47 1.8 14 

136-04 9-30-1999 -- 11 .9 21 1.9 16 

136-04 1-10-2000 -- 11 .8 200 1.5 11 

136-04 3-17-2000 -- 5 .5 76 .8 7.3 

136-04 6-02-2000 -- 8.5 .7 37 1.3 13 

136-05 9-30-1999 -- 6.6 .6 11 1.4 9.5 

136-05 1-10-2000 -- 8.5 .6 150 1.3 9.5 

136-05 3-17-2000 -- 3.4 .3 49 .5 5.2 

136-05-R 3-17-2000 -- 3.4 .3 49 .5 5.3 

136-05 6-02-2000 -- 6.8 .5 25 .9 9.8 

Quality-control samples—Continued

Deionized water blanks

USGS-MA Laboratory 7-12-1999 -- <0.02 <0.004 <0.06 <0.1 <0.1 

USGS-MA Laboratory 2-08-2000 -- <.02 <.014 <.09 <.24 <.31 

Ambient-atmospheric blanks

USGS-MA Laboratory 7-12-1999 -- -- -- -- -- -- 

USGS-MA Laboratory 2-08-2000 -- -- -- -- -- -- 

Equipment blanks

USGS-MA Laboratory 9-28-1999 -- -- -- <.09 <.24 <.31 

USGS-MA Laboratory 6-01-2000 -- -- -- -- -- -- 

Material blanks

USGS-MA Laboratory 7-29-1998 -- -- -- -- -- -- 

USGS-MA Laboratory 3-18-1999 -- -- -- -- -- -- 
Table 1H. Physical properties and event mean concentrations of major inorganic constituents, nutrients, trace metals, 

suspended sediments, fecal-indicator bacteria, and semi-volatile organic compounds for highway runoff event mean 

concentrations from sequential points within the drainage system of the Southeast Expressway near Boston, Massach

Continued

Station

identifier Date

Fluoride,

dissolved

(mg/L as F)

Silica,

dissolved

(mg/L as 

SIO2)

Solids, residue

at 180 ̊C,

dissolved

(mg/L)

Residue, total 

at 105 ̊C,

suspended

(mg/L)

Nitrogen,

nitrite

dissolved

(mg/L as N)

Ni

NO

dis

(mg

Environmental samples—Continued

739-02 9-30-1999 0.4 2.7 94 -- 0.07 

739-02-R 9-30-1999 .4 2.7 98 -- .07 

739-02 1-10-2000 .3 1.5 325 188 .09 

739-02 3-17-2000 .1 .9 520 38 .03 

739-02 6-02-2000 .5 1.9 226 -- .11 

739-03 9-30-1999 -- -- -- -- .08 

739-03-R 9-30-1999 .5 2.5 88 -- .08 

739-03 1-10-2000 .3 1.7 382 192 .10 

739-03-R 1-10-2000 .3 1.7 380 186 .09 

739-03 3-17-2000 .2 1.1 2,300 126 .06 

739-03 6-02-2000 .5 1.6 201 -- .08 

136-02 9-30-1999 .6 3.0 131 -- .12 

136-02 1-10-2000 .3 1.8 428 216 .10 

136-02-R 1-10-2000 .3 1.8 428 224 .10 

136-02 3-17-2000 .1 .9 441 112 .03 

136-02 6-02-2000 .4 1.8 170 -- .08 

136-03 9-30-1999 .5 2.5 117 -- .11 

136-03 1-10-2000 .3 1.9 475 230 .10 

136-03 3-17-2000 .1 .9 498 150 .04 

136-03 6-02-2000 .4 1.7 179 -- .08 

136-04 9-30-1999 .5 2.1 115 -- .08 

136-04 1-10-2000 .2 1.5 590 272 .08 

136-04 3-17-2000 .1 .6 222 100 .03 

136-04 6-02-2000 .4 1.0 157 -- .06 

136-05 9-30-1999 .4 1.2 73 -- .09 

136-05 1-10-2000 .2 1.2 447 286 .07 

136-05 3-17-2000 <.1 .5 141 119 .02 

136-05-R 3-17-2000 <.1 .5 <.3 -- .02 

136-05 6-02-2000 .3 .9 117 -- .03 

Quality-control samples—Continued

Deionized water blanks

USGS-MA Laboratory 7-12-1999 <0.1 E0.038 <10 -- <0.01 <

USGS-MA Laboratory 2-08-2000 <.1 E.0577 <10 -- <.01 

Ambient-atmospheric blanks

USGS-MA Laboratory 7-12-1999 -- -- -- -- <.01 

USGS-MA Laboratory 2-08-2000 -- -- -- -- <.01 

Equipment blanks

USGS-MA Laboratory 9-28-1999 <.1 <.09 <10 -- <.01 

USGS-MA Laboratory 6-01-2000 -- -- -- -- -- 

Material blanks

USGS-MA Laboratory 7-29-1998 -- -- -- -- -- 

USGS-MA Laboratory 3-18-1999 -- -- -- -- -- 
Table 1H. Physical properties and event mean concentrations of major inorganic constituents, nutrients, trace metals, 

suspended sediments, fecal-indicator bacteria, and semi-volatile organic compounds for highway runoff event mean 

concentrations from sequential points within the drainage system of the Southeast Expressway near Boston, Massach

Continued

Station

identifier Date

Nitrogen,

ammonia,

dissolved

(mg/L as N)

Nitrogen,

ammonia +

organic,

total

(mg/L as N)

Nitrogen,

ammonia +

organic,

dissolved

(mg/L as N)

Phosphorus,

total

(mg/L as P)

Phosphorus,

dissolved

(mg/L as P)

Pho

o

dis

(mg

Environmental samples—Continued

739-02 9-30-1999 0.37 0.16 0.76 0.18 0.04 

739-02-R 9-30-1999 .37 .75 .61 .04 .08 

739-02 1-10-2000 .69 1.8 .95 .32 .03 

739-02 3-17-2000 .42 .87 .56 .17 .04 

739-02 6-02-2000 .75 2.8 1.4 .50 .03 

739-03 9-30-1999 .42 1.4 .81 .25 .05 

739-03-R 9-30-1999 .42 1.4 .81 .24 .05 

739-03 1-10-2000 .74 1.8 1.0 2.5 .03 

739-03-R 1-10-2000 .74 2.0 1.0 .36 .03 

739-03 3-17-2000 .81 1.3 1.0 .19 .03 

739-03 6-02-2000 .72 2.9 1.4 .62 .02 

136-02 9-30-1999 .66 2.1 1.3 .29 .06 

136-02 1-10-2000 .75 2.0 1.1 .38 .03 

136-02-R 1-10-2000 .71 2.1 1.1 .39 .03 

136-02 3-17-2000 .52 1.1 .68 .19 .01 

136-02 6-02-2000 .55 2.3 1.1 .42 .04 

136-03 9-30-1999 .54 1.3 1.2 .24 .07 

136-03 1-10-2000 .75 2.1 1.1 .50 .03 

136-03 3-17-2000 .55 1.4 .80 .30 .02 

136-03 6-02-2000 .67 2.8 1.3 .64 .04 

136-04 9-30-1999 1.1 2.4 1.6 .39 .10 

136-04 1-10-2000 .69 2.0 1.0 .46 .04 

136-04 3-17-2000 .51 1.3 .64 .17 .01 

136-04 6-02-2000 1.1 3.5 1.8 .70 .08 

136-05 9-30-1999 .87 2.2 1.3 .43 .10 

136-05 1-10-2000 .72 2.1 1.0 .53 .05 

136-05 3-17-2000 .37 .88 .45 .43 .02 

136-05-R 3-17-2000 .36 .86 .43 .32 .02 

136-05 6-02-2000 .79 3.8 1.3 .90 .08 

Quality-control samples—Continued

Deionized water blanks

USGS-MA Laboratory 7-12-1999 <0.02 -- E0.051 -- <0.004 <

USGS-MA Laboratory 2-08-2000 <.02 -- <.1 -- <.006 

Ambient-atmospheric blanks

USGS-MA Laboratory 7-12-1999 <.02 -- <.1 -- <.004 

USGS-MA Laboratory 2-08-2000 <.02 -- <.1 -- <.006 

Equipment blanks

USGS-MA Laboratory 9-28-1999 <.02 0.257 <.1 <0.008 <.006 

USGS-MA Laboratory 6-01-2000 -- -- -- -- -- 

Material blanks

USGS-MA Laboratory 7-29-1998 -- -- -- -- -- 

USGS-MA Laboratory 3-18-1999 -- -- -- -- -- 
Table 1H. Physical properties and event mean concentrations of major inorganic constituents, nutrients, trace metals, 

suspended sediments, fecal-indicator bacteria, and semi-volatile organic compounds for highway runoff event mean 

concentrations from sequential points within the drainage system of the Southeast Expressway near Boston, Massach

Continued

Station

identifier Date

Aluminum,

dissolved

(μg/L as Al)

Antimony,

dissolved

(μg/L as Sb)

Arsenic,

total

(μg/L as As)

Arsenic,

dissolved

(μg/L as As)

Barium,

dissolved

(μg/L as Ba)

Ber

t

reco

(μg/L 

Environmental samples—Continued

739-02 9-30-1999 -- -- E2 -- -- 

739-02-R 9-30-1999 -- -- E2 -- -- 

739-02 1-10-2000 26 1 E2 <2 34 

739-02 3-17-2000 E2 -- -- 

739-02 6-02-2000 -- -- 4 -- -- 

739-03 9-30-1999 -- -- E1 -- -- 

739-03-R 9-30-1999 -- -- E2 -- -- 

739-03 1-10-2000 24 1 E2 <2 37 

739-03-R 1-10-2000 28 2 3 <2 41 

739-03 3-17-2000 -- -- E2 -- -- 

739-03 6-02-2000 -- -- 4 -- -- 

136-02 9-30-1999 -- -- E2 -- 

136-02 1-10-2000 18 2 E3 <2 37 

136-02-R 1-10-2000 18 2 E2 <2 42 

136-02 3-17-2000 -- -- E2 -- -- 

136-02 6-02-2000 -- -- 3 -- -- 

136-03 9-30-1999 -- -- 3 -- -- 

136-03 1-10-2000 11 2 3 <2 41 

136-03 3-17-2000 -- -- 4 -- -- 

136-03 6-02-2000 -- -- 4 -- -- 

136-04 9-30-1999 -- -- E3 -- -- 

136-04 1-10-2000 25 2 3 <2 46 

136-04 3-17-2000 -- -- E2 -- -- 

136-04 6-02-2000 -- -- 4 -- -- 

136-05 9-30-1999 -- -- 3 -- -- 

136-05 1-10-2000 24 2 4 <2 38 

136-05 3-17-2000 -- -- 5 -- -- 

136-05-R 3-17-2000 -- -- 3 -- -- 

136-05 6-02-2000 -- -- 6 -- -- 

Quality-control samples—Continued

Deionized water blanks

USGS-MA Laboratory 7-12-1999 <1 <1 -- <1 <1 

USGS-MA Laboratory 2-08-2000 <1 <1 -- <2 <1 

Ambient-atmospheric blanks

USGS-MA Laboratory 7-12-1999 <1 <1 -- <1 <1 

USGS-MA Laboratory 2-08-2000 <1 <1 -- <2 <1 

Equipment blanks

USGS-MA Laboratory 9-28-1999 -- -- <2.6 -- -- 

USGS-MA Laboratory 6-01-2000 -- -- -- -- -- 

Material blanks

USGS-MA Laboratory 7-29-1998 2.08 <1 -- <1 <1 

USGS-MA Laboratory 3-18-1999 -- -- -- -- -- 
Table 1H. Physical properties and event mean concentrations of major inorganic constituents, nutrients, trace metals, 

suspended sediments, fecal-indicator bacteria, and semi-volatile organic compounds for highway runoff event mean 

concentrations from sequential points within the drainage system of the Southeast Expressway near Boston, Massach

Continued

Station

identifier Date

Beryllium,

dissolved

(μg/L as Be)

Cadmium,

water

unfiltered,

total

(μg/L as Cd)

Cadmium,

dissolved

(μg/L as Cd)

Chromium,

total

recoverable

(μg/L as Cr)

Chromium,

dissolved

(μg/L as Cr)

C

dis

(μg/

Environmental samples—Continued

739-02 9-30-1999 -- 1 20 -- 

739-02-R 9-30-1999 -- 1 20 -- 

739-02 1-10-2000 <1 2 <1 25 10 

739-02 3-17-2000 -- 1 -- 12 -- 

739-02 6-02-2000 -- 2 -- 37 -- 

739-03 9-30-1999 -- 1 -- 20 -- 

739-03-R 9-30-1999 -- 1 -- 20 -- 

739-03 1-10-2000 <1 2 <1 25 11 

739-03-R 1-10-2000 <1 2 <1 26 9.5 

739-03 3-17-2000 -- 3 -- 15 -- 

739-03 6-02-2000 -- 2 -- 40 -- 

136-02 9-30-1999 -- 1 -- 19 -- 

136-02 1-10-2000 <1 2 <1 22 6.0 

136-02-R 1-10-2000 <1 2 <1 21 6.1 

136-02 3-17-2000 -- 1 -- 19 -- 

136-02 6-02-2000 -- 2 -- 40 -- 

136-03 9-30-1999 -- 2 -- 24 -- 

136-03 1-10-2000 <1 .3 <1 25 6.2 

136-03 3-17-2000 -- 3 -- 46 -- 

136-03 6-02-2000 -- 2 -- 45 -- 

136-04 9-30-1999 -- 2 -- 33 -- 

136-04 1-10-2000 <1 3 <1 34 13 

136-04 3-17-2000 -- 1 -- 18 -- 

136-04 6-02-2000 -- 3 -- 68 -- 

136-05 9-30-1999 -- 2 -- 40 -- 

136-05 1-10-2000 <1 3 <1 38 14 

136-05 3-17-2000 -- 2 -- 41 -- 

136-05-R 3-17-2000 -- 1 -- 30 -- 

136-05 6-02-2000 -- 3 -- 90 -- 

Quality-control samples—Continued

Deionized water blanks

USGS-MA Laboratory 7-12-1999 <1 -- <1 -- <1 

USGS-MA Laboratory 2-08-2000 <1 -- <1 -- <.8 

Ambient-atmospheric blanks

USGS-MA Laboratory 7-12-1999 <1 -- <1 -- <1 

USGS-MA Laboratory 2-08-2000 <1 -- <1 -- <.8 

Equipment blanks

USGS-MA Laboratory 9-28-1999 -- <0.11 -- <1 -- 

USGS-MA Laboratory 6-01-2000 -- -- -- -- -- 

Material blanks

USGS-MA Laboratory 7-29-1998 <1 -- <1 -- <1 

USGS-MA Laboratory 3-18-1999 -- -- -- -- -- 
Table 1H. Physical properties and event mean concentrations of major inorganic constituents, nutrients, trace metals, 

suspended sediments, fecal-indicator bacteria, and semi-volatile organic compounds for highway runoff event mean 

concentrations from sequential points within the drainage system of the Southeast Expressway near Boston, Massach

Continued

Station

identifier Date

Copper, total

recoverable

(μg/L as Cu)

Copper,

dissolved

(μg/l as Cu)

Iron, total

recoverable

(μg/L as Fe)

Iron,

dissolved

(μg/L as Fe)

Lead, total

recoverable

(μg/L as Pb)

dis

(μg/

Environmental samples—Continued

739-02 9-30-1999 86 -- 6,900 150 47 

739-02-R 9-30-1999 85 -- 7,000 140 47 

739-02 1-10-2000 110 11 7,900 <10 71 

739-02 3-17-2000 60 -- 3,800 <10 38 

739-02 6-02-2000 140 -- 11,000 330 78 

739-03 9-30-1999 90 -- 6,930 -- 46 

739-03-R 9-30-1999 86 -- 7,100 150 46 

739-03 1-10-2000 120 13 8,700 10 74 

739-03-R 1-10-2000 110 13 9,000 E8 73 

739-03 3-17-2000 70 -- 5,100 <30 43 

739-03 6-02-2000 180 -- 11,000 150 129 

136-02 9-30-1999 89 -- 6,400 75 76

136-02 1-10-2000 130 13 9,100 E9 86 

136-02-R 1-10-2000 130 14 8,900 14 85 

136-02 3-17-2000 78 -- 5,600 <10 53 

136-02 6-02-2000 130 -- 8,300 355 73 

136-03 9-30-1999 100 -- 9,800 102 81 

136-03 1-10-2000 150 15 11,000 16 90 

136-03 3-17-2000 170 -- 22,000 E6 120 

136-03 6-02-2000 9,600

(9,600)

-- 11,000 290 210 

136-04 9-30-1999 110 -- 9,500 21 74 

136-04 1-10-2000 150 13 11,000 E6 110 

136-04 3-17-2000 54 -- 5,300 <10 43 

136-04 6-02-2000 180 -- 10,000 30 110 

136-05 9-30-1999 130 -- 11,000 26 88 

136-05 1-10-2000 150 12 18,000 E7 100 

136-05 3-17-2000 130 -- 29,000 <10 110 

136-05-R 3-17-2000 91 -- 14,000 <10 74 

136-05 6-02-2000 280 -- 15,000 21 170 

Quality-control samples—Continued

Deionized water blanks

USGS-MA Laboratory 7-12-1999 -- <1 -- <10 -- 

USGS-MA Laboratory 2-08-2000 -- <1 -- <10 -- 

Ambient-atmospheric blanks

USGS-MA Laboratory 7-12-1999 -- <1 -- -- -- 

USGS-MA Laboratory 2-08-2000 -- <1 -- -- -- 

Equipment blanks

USGS-MA Laboratory 9-28-1999 <1.2 -- <21 <10 <1 

USGS-MA Laboratory 6-01-2000 -- -- -- -- -- 

Material blanks

USGS-MA Laboratory 7-29-1998 -- <1 -- <1 -- 

USGS-MA Laboratory 3-18-1999 -- -- -- -- -- 
Table 1H. Physical properties and event mean concentrations of major inorganic constituents, nutrients, trace metals, 

suspended sediments, fecal-indicator bacteria, and semi-volatile organic compounds for highway runoff event mean 

concentrations from sequential points within the drainage system of the Southeast Expressway near Boston, Massach

Continued

Station

identifier Date

Manganese,

total

recoverable

(μg/L as Mn)

Manganese,

dissolved

(μg/L as Mn)

Mercury,

total

recoverable

(μg/L as Hg)

Molybdenum,

dissolved

(μg/L as Mo)

Nickel, total

recoverable

(μg/L as Ni)

N

di

(μg

Environmental samples—Continued

739-02 9-30-1999 150 37 <0.1 -- 12 

739-02-R 9-30-1999 150 37 <.1 -- 11 

739-02 1-10-2000 170 24 <.3 2 14 

739-02 3-17-2000 85 25 <.3 -- 6 

739-02 6-02-2000 230 79 <.3 -- 17 

739-03 9-30-1999 150 -- <.1 -- 11 

739-03-R 9-30-1999 150 35 <.1 -- 13 

739-03 1-10-2000 180 28 <.3 2 15 

739-03-R 1-10-2000 190 29 <.3 2 16 

739-03 3-17-2000 140 56 <.3 -- 9 

739-03 6-02-2000 260 74 <.3 -- 19 

136-02 9-30-1999 150 45 <.1 -- 12 

136-02 1-10-2000 190 35 <.3 2 17 

136-02-R 1-10-2000 190 37 <.3 2 16 

136-02 3-17-2000 110 27 <.3 -- 9 

136-02 6-02-2000 170 58 -- -- 14 

136-03 9-30-1999 220 35 <.1 -- 15 

136-03 1-10-2000 270 41 <.3 3 19 

136-03 3-17-2000 510 30 <.3 -- 22 

136-03 6-02-2000 230 62 <.3 -- 17 

136-04 9-30-1999 220 56 <.1 -- 17 

136-04 1-10-2000 230 36 <.3 3 16 

136-04 3-17-2000 110 29 <.3 -- 9 

136-04 6-02-2000 240 72 <.3 -- 20 

136-05 9-30-1999 230 39 <.1 -- 18 

136-05 1-10-2000 360 30 <.3 3 23 

136-05 3-17-2000 930 20 <.3 -- 22 

136-05-R 3-17-2000 230 20 <.1 -- 14 

136-05 6-02-2000 310 59 -- -- 24 

Quality-control samples—Continued

Deionized water blanks

USGS-MA Laboratory 7-12-1999 -- <1 <1 <1 -- 

USGS-MA Laboratory 2-08-2000 -- <1 <.2 <1 -- 

Ambient-atmospheric blanks

USGS-MA Laboratory 7-12-1999 -- <1 -- <1 -- 

USGS-MA Laboratory 2-08-2000 -- <1 -- <1 -- 

Equipment blanks

USGS-MA Laboratory 9-28-1999 <2.8 <2.2 <1 -- -- 

USGS-MA Laboratory 6-01-2000 -- -- -- -- -- 

Material blanks

USGS-MA Laboratory 7-29-1998 -- <1 -- <1 -- 

USGS-MA Laboratory 3-18-1999 -- -- -- -- -- 
Table 1H. Physical properties and event mean concentrations of major inorganic constituents, nutrients, trace metals, 

suspended sediments, fecal-indicator bacteria, and semi-volatile organic compounds for highway runoff event mean 

concentrations from sequential points within the drainage system of the Southeast Expressway near Boston, Massach

Continued

Station

identifier Date

Selenium,

total

(μg/L as Se)

Selenium,

dissolved

(μg/L as Se)

Silver,

dissolved

(μg/L as Ag)

Zinc, total

recoverable

(μg/L as Zn)

Zinc,

dissolved

(μg/L as Zn)

Ur

n

dis

(μg

Environmental samples—Continued

739-02 9-30-1999 <3 -- -- 310 -- 

739-02-R 9-30-1999 <3 -- -- 310 -- 

739-02 1-10-2000 <3 <2 <1 490 25 

739-02 3-17-2000 <3 -- 240 -- 

739-02 6-02-2000 <3 -- -- 870 -- 

739-03 9-30-1999 <3 -- -- 320 -- 

739-03-R 9-30-1999 <3 -- -- 320 -- 

739-03 1-10-2000 <3 <2 <1 490 34 

739-03-R 1-10-2000 <3 <2 <1 480 33 

739-03 3-17-2000 <3 -- -- 340 -- 

739-03 6-02-2000 <3 -- -- 1,070 -- 

136-02 9-30-1999 <3 -- -- 320 -- 

136-02 1-10-2000 <3 <2 <1 510 53 

136-02-R 1-10-2000 <3 <2 <1 510 51 

136-02 3-17-2000 <3 -- -- 340 -- 

136-02 6-02-2000 <3 -- -- 610 -- 

136-03 9-30-1999 <3 -- -- 480 -- 

136-03 1-10-2000 <3 <2 <1 560 73 

136-03 3-17-2000 <3 -- -- 890 -- 

136-03 6-02-2000 E1 -- -- 1,100 -- 

136-04 9-30-1999 <3 -- -- 470 -- 

136-04 1-10-2000 <3 <2 <1 590 31 

136-04 3-17-2000 <3 -- -- 360 -- 

136-04 6-02-2000 E1 -- -- 1,580 -- 

136-05 9-30-1999 <3 -- -- 530 -- 

136-05 1-10-2000 <3 <2 <1 660 30 

136-05 3-17-2000 <3 -- -- 850 -- 

136-05-R 3-17-2000 <3 -- -- 620 -- 

136-05 6-02-2000 E2 -- -- 2,200 -- 

Quality-control samples—Continued

Deionized water blanks

USGS-MA Laboratory 7-12-1999 -- <1 <1 -- <1 

USGS-MA Laboratory 2-08-2000 -- <2 <1 -- <1 

Ambient-atmospheric blanks

USGS-MA Laboratory 7-12-1999 -- <1 <1 -- <1 

USGS-MA Laboratory 2-08-2000 -- <2 <1 -- <1 

Equipment blanks

USGS-MA Laboratory 9-28-1999 <3 -- -- <31 -- 

USGS-MA Laboratory 6-01-2000 -- -- -- -- -- 

Material blanks

USGS-MA Laboratory 7-29-1998 -- <1 <1 -- <1 

USGS-MA Laboratory 3-18-1999 -- -- -- -- -- 
Table 1H. Physical properties and event mean concentrations of major inorganic constituents, nutrients, trace metals, 

suspended sediments, fecal-indicator bacteria, and semi-volatile organic compounds for highway runoff event mean 

concentrations from sequential points within the drainage system of the Southeast Expressway near Boston, Massach

Continued

Station

identifier Date

Carbon,

organic

suspended

(mg/L as C)

Carbon,

organic

dissolved

(mg/L as C)

Cyanide,

total

(mg/L as 

Cn)

Oil and grease,

total

recoverable

gravimetric

(mg/L)

1,2,5,6

-Dibenzanthracene,

total

(ug/L)

Ac

t

Environmental samples—Continued

739-02 9-30-1999 3.1 9.7 -- 7 <3.4 

739-02-R 9-30-1999 3.2 8.7 -- 7 <3.4 

739-02 1-10-2000 4.8 4.6 -- -- E.2 

739-02 3-17-2000 >4.3 15 -- 5 <3.4 

739-02 6-02-2000 >6.3 13 -- 10 E.3 

739-03 9-30-1999 1.3 8.7 -- 6 <3.4 

739-03-R 9-30-1999 3.4 10 -- -- -- 

739-03 1-10-2000 >4.9 5.2 <0.01 11 E.2 

739-03-R 1-10-2000 5.3 -- 9 E.2 

739-03 3-17-2000 4.1 11 -- 6 <3.4 

739-03 6-02-2000 >9.8 14 -- 11 E.6 

136-02 9-30-1999 3.8 -- -- 8 <3.4 

136-02 1-10-2000 >5 6.0 -- 11 E.3 

136-02-R 1-10-2000 -- -- -- E.2 

136-02 3-17-2000 >6 4.4 -- 5 <3.4 

136-02 6-02-2000 >8.5 11 -- -- -- 

136-03 9-30-1999 4.3 11 -- 8. <3.4 

136-03 1-10-2000 4.2 6.0 <.01 12 E.3 

136-03 3-17-2000 >5.1 5.0 -- 7 <3.4 

136-03 6-02-2000 >6 14 -- -- E.5 

136-04 9-30-1999 3.4 16 -- 12 <3.4 

136-04 1-10-2000 3.3 6.9 -- 17 E.2 

136-04 3-17-2000 3.4 4.1 -- 4 <3.4 

136-04 6-02-2000 >5.2 18 -- -- -- 

136-05 9-30-1999 1.4 13 -- -- <3.4 

136-05 1-10-2000 >5.1 6.6 -- 18 E.2 

136-05 3-17-2000 >4.3 3.0 -- 8 -- 

136-05-R 3-17-2000 >6.3 3.0 -- 7 <3.4 

136-05 6-02-2000 >5.5 14 -- -- -- 

Quality-control samples—Continued

Deionized water blanks

USGS-MA Laboratory 7-12-1999 -- <1 -- -- <10 

USGS-MA Laboratory 2-08-2000 -- <.3 -- -- <3.4 

Ambient-atmospheric blanks

USGS-MA Laboratory 7-12-1999 -- .3 -- -- -- 

USGS-MA Laboratory 2-08-2000 -- <.3 -- -- -- 

Equipment blanks

USGS-MA Laboratory 9-28-1999 -- E.2 -- <1 <3.4 

USGS-MA Laboratory 6-01-2000 -- <.3 -- -- -- 

Material blanks

USGS-MA Laboratory 7-29-1998 -- -- -- -- -- 

USGS-MA Laboratory 3-18-1999 -- -- -- -- <10 
Table 1H. Physical properties and event mean concentrations of major inorganic constituents, nutrients, trace metals, 

suspended sediments, fecal-indicator bacteria, and semi-volatile organic compounds for highway runoff event mean 

concentrations from sequential points within the drainage system of the Southeast Expressway near Boston, Massach

Continued

Station

identifier Date

Acenphthene, total

(ug/L)

Anthracene, total

(ug/L)

Aroclor 1221,

pcb total

(ug/L)

Aroclor 1232,

pcb total

(ug/L)

Aroclor 1248,

pcb total

(ug/L)

Aroc

pc

(u

Environmental samples—Continued

739-02 9-30-1999 E0.05 E0.1 <0.1 <0.1 <0.1 <

739-02-R 9-30-1999 E.1 E.1 <.1 <.1 <.1 

739-02 1-10-2000 E.1 E0.2 <.2 <.2 <.2 E

739-02 3-17-2000 <1.9 E.1 <.1 <.1 <.1 

739-02 6-02-2000 E.1 E.2 <.1 <.1 <.1 

739-03 9-30-1999 E.1 E.2 <.1 < .1 <.1 

739-03-R 9-30-1999 -- -- -- -- -- -

739-03 1-10-2000 E.1 E.2 <.2 <.2 <.2 E

739-03-R 1-10-2000 E.1 E.2 <.2 <.2 <.2 E

739-03 3-17-2000 E.04 E.1 <.1 <.1 <.1 

739-03 6-02-2000 E.2 E.3 <.1 <.1 <.1 

136-02 9-30-1999 E.1 E.2 -- -- -- -

136-02 1-10-2000 E.1 E.3 <.2 <.2 <.2 E

136-02-R 1-10-2000 E.1 E.2 <.2 <.2 <.2 E

136-02 3-17-2000 E.04 E.1 <.1 <.1 <.1 

136-02 6-02-2000 -- -- -- -- -- -

136-03 9-30-1999 <1.9 E.1 <.1 <.1 <.1 

136-03 1-10-2000 E.1 E.3 <.2 <.2 <.2 E

136-03 3-17-2000 E.1 E.1 <.1 <.1 <.1 

136-03 6-02-2000 E.1 E.2 -- -- -- -

136-04 9-30-1999 E.1 E.2 <.1 <.1 <.1 

136-04 1-10-2000 E.2 E.3 <.2 <.2 <.2 E

136-04 3-17-2000 <1.9 E.1 <.1 <.1 <.1 

136-04 6-02-2000 -- -- -- -- -- -

136-05 9-30-1999 E.1 E.3 <.1 < .1 <.1 

136-05 1-10-2000 E.1 E.3 <.2 <.2 <.2 E

136-05 3-17-2000 -- -- <.1 <.1 <.1 

136-05-R 3-17-2000 E.1 E.3 <.1 <.1 <.1 

136-05 6-02-2000 -- -- -- -- -- -

Quality-control samples—Continued

Deionized water blanks

USGS-MA Laboratory 7-12-1999 <5 <5 <.1 <.1 <.1 

USGS-MA Laboratory 2-08-2000 <1.9 <2 <.1 <.1 -- 

Ambient-atmospheric blanks

USGS-MA Laboratory 7-12-1999 -- -- -- -- -- -

USGS-MA Laboratory 2-08-2000 -- -- -- -- -- -

Equipment blanks

USGS-MA Laboratory 9-28-1999 <1.9 <2 <.1 <.1 <.1 

USGS-MA Laboratory 6-01-2000 -- -- -- -- -- -

Material blanks

USGS-MA Laboratory 7-29-1998 -- -- -- -- -- -

USGS-MA Laboratory 3-18-1999 <.5 <.5 <.1 <.1 <.1 
Table 1H. Physical properties and event mean concentrations of major inorganic constituents, nutrients, trace metals, 

suspended sediments, fecal-indicator bacteria, and semi-volatile organic compounds for highway runoff event mean 

concentrations from sequential points within the drainage system of the Southeast Expressway near Boston, Massach

Continued

Station

identifier Date

Aroclor 1260,

pcb total

(ug/L)

Aroclor

1016/1242,

pcb total

(ug/L)

Benzoapyrene,

total

(ug/L)

Benzo B

fluoranthene,

total

(ug/L)

Benzo K

fluoranthene,

total

(ug/L)

Ben

pe

(

Environmental samples—Continued

739-02 9-30-1999 <0.1 -- E0.4 E0.7 E0.2 E

739-02-R 9-30-1999 <.1 -- E.4 E.6 E.2 

739-02 1-10-2000 E.03 E.03 E.8 E1.1 E.8 

739-02 3-17-2000 <.1 <.1 E.3 E.5 E.3 

739-02 6-02-2000 <.1 <.1 E1.1 E1.4 E1.2 

739-03 9-30-1999 <.1 -- E.5 E.7 E.3 

739-03-R 9-30-1999 -- -- -- -- -- 

739-03 1-10-2000 E.03 E.03 E.6 E.8 E.5 

739-03-R 1-10-2000 E.03 E.03 E.7 E.9 E.6 E

739-03 3-17-2000 <.1 <.1 E.3 E.5 E.4 

739-03 6-02-2000 <.1 <.1 E1.6 E1.9 E1.8 E

136-02 9-30-1999 -- -- E.5 E.8 E.2 

136-02 1-10-2000 E.03 E.04 E1.0 E1.1 E.8 E

136-02-R 1-10-2000 E.04 E.04 E.7 E.9 E.7 E

136-02 3-17-2000 <.1 <.1 E.4 E.7 E.5 

136-02 6-02-2000 -- -- -- -- -- 

136-03 9-30-1999 < .1 -- E.3 E.6 E.3 

136-03 1-10-2000 E.04 E.05 E.9 E1.1 E.8 E

136-03 3-17-2000 <.1 <.1 E.5 E.8 E.5 

136-03 6-02-2000 -- -- E1.3 E2.0 E1.4 E

136-04 9-30-1999 <.1 -- E.6 E1.0 E.4 

136-04 1-10-2000 E.06 E.03 E.8 E1.3 E.9 

136-04 3-17-2000 <.1 <.1 E.3 E.5 E.3 

136-04 6-02-2000 -- -- -- -- -- 

136-05 9-30-1999 <.1 -- E.8 E1.2 E.5 

136-05 1-10-2000 E.07 E.03 E1.0 E1.5 E1.0 E

136-05 3-17-2000 <.1 <.1 -- -- -- 

136-05-R 3-17-2000 <.1 <.1 E.9 E1.2 E1.0 

136-05 6-02-2000 -- -- -- -- -- 

Quality-control samples—Continued

Deionized water blanks

USGS-MA Laboratory 7-12-1999 <.1 <.1 <10 <10 <10 <

USGS-MA Laboratory 2-08-2000 <.1 <.1 <2.8 <3.0 <3.2 9

Ambient-atmospheric blanks

USGS-MA Laboratory 7-12-1999 -- -- -- -- -- 

USGS-MA Laboratory 2-08-2000 -- -- -- -- -- 

Equipment blanks

USGS-MA Laboratory 9-28-1999 <.1 <.1 <2.8 <3.0 <3.0 <

USGS-MA Laboratory 6-01-2000 -- -- -- -- -- 

Material blanks

USGS-MA Laboratory 7-29-1998 -- -- -- -- -- 

USGS-MA Laboratory 3-18-1999 <.1 <.1 <10 <10 <10 <
Table 1H. Physical properties and event mean concentrations of major inorganic constituents, nutrients, trace metals, 

suspended sediments, fecal-indicator bacteria, and semi-volatile organic compounds for highway runoff event mean 

concentrations from sequential points within the drainage system of the Southeast Expressway near Boston, Massach

Continued

Station

identifier Date

Chrysene,

total

(ug/L)

Fluoranthene,

total

(ug/L)

Fluorene,

total

(ug/L)

Petroleum

hydrocarbons,

total

(mg/L)

Indeno

(1,2,3 CD)

pyrene, total

(ug/L)

Phena

t

(u

Environmental samples—Continued

739-02 9-30-1999 E0.6 E0.9 E0.1 <0.1 E0.3 E

739-02-R 9-30-1999 E.7 E.9 E.1 <.1 E.2 

739-02 1-10-2000 E1.2 E1.8 E.2 7 E.8 

739-02 3-17-2000 E.5 E.8 E.1 2.1 E.3 

739-02 6-02-2000 E1.7 2.5 E.1 5.9 E1.1 E

739-03 9-30-1999 E.6 E1.1 E.2 <.1 E.3 

739-03-R 9-30-1999 -- -- -- -- -- 

739-03 1-10-2000 E1.0 E1.5 E.1 5 E.7 

739-03-R 1-10-2000 E1.1 E1.6 E.1 6 E.7 

739-03 3-17-2000 E.6 E1.0 E.1 2.7 E.3 

739-03 6-02-2000 E2.4 3.6 E.2 4.7 E1.8 E

136-02 9-30-1999 E.8 E1.2 E.1 -- E.4 

136-02 1-10-2000 E1.6 E2.2 E.1 7 E1.1 

136-02-R 1-10-2000 E1.2 E1.6 E.1 -- E.9 

136-02 3-17-2000 E.7 E1.4 E.1 3.6 E.4 

136-02 6-02-2000 -- -- -- 4.8 -- 

136-03 9-30-1999 E.5 E.9 E.1 <.1 E.3 

136-03 1-10-2000 E1.5 E2.0 E.2 6 E.9 E

136-03 3-17-2000 E.9 E1.6 E.1 4.1 E.4 

136-03 6-02-2000 E2.0 2.4 E.1 5.9 E1.4 E

136-04 9-30-1999 E1.2 E1.5 E.1 <.1 E.4 

136-04 1-10-2000 E1.6 E2.3 E.5 10 E.8 E

136-04 3-17-2000 E.5 E.9 E.1 3.3 E.3 

136-04 6-02-2000 -- -- -- 8.9 -- 

136-05 9-30-1999 E1.3 E1.9 E.18 <.1 E.6 E

136-05 1-10-2000 E1.8 2.7 E.3 10 E.9 E

136-05 3-17-2000 -- -- -- 3.0 -- 

136-05-R 3-17-2000 E1.4 2.9 .2 2.9 E.7 E

136-05 6-02-2000 -- -- -- 9.8 -- 

Quality-control samples—Continued

Deionized water blanks

USGS-MA Laboratory 7-12-1999 <10 <5 <5 -- <10 <

USGS-MA Laboratory 2-08-2000 <2.7 <2.33 <2.04 <.1 <3 <

Ambient-atmospheric blanks

USGS-MA Laboratory 7-12-1999 -- -- -- -- -- 

USGS-MA Laboratory 2-08-2000 -- -- -- -- -- 

Equipment blanks

USGS-MA Laboratory 9-28-1999 <2.7 <2.33 <2.04 <.1 <3 <

USGS-MA Laboratory 6-01-2000 -- -- -- -- -- 

Material blanks

USGS-MA Laboratory 7-29-1998 -- -- -- -- -- 

USGS-MA Laboratory 3-18-1999 <10 <.5 <.5 -- <10 
Table 1H. Physical properties and event mean concentrations of major inorganic constituents, nutrients, trace metals, 

suspended sediments, fecal-indicator bacteria, and semi-volatile organic compounds for highway runoff event mean 

concentrations from sequential points within the drainage system of the Southeast Expressway near Boston, Massach

Continued

Station

identifier Date

Pyrene,

total

(ug/L)

Naphthalene,

total

(ug/L)

Suspended

sediment

(mg/L)

Suspended

sediment,

<.062 mm

(mg/L)

Suspended

sediment,

0.062 to

0.250 mm

(mg/L)

Sus

sed

> 0.

(m

Environmental samples—Continued

739-02 9-30-1999 E0.9 E0.1 174 171 2 

739-02-R 9-30-1999 E.8 E.1 183 180 2 

739-02 1-10-2000 E1.6 E.2 219 213 4 

739-02 3-17-2000 E.7 <2.1 92 87 3 

739-02 6-02-2000 2.3 E.1 340 305 25 

739-03 9-30-1999 E1.0 E .2 193 169 4 

739-03-R 9-30-1999 -- -- -- -- -- 

739-03 1-10-2000 E1.3 E.2 261 205 10 

739-03-R 1-10-2000 E1.4 E.2 714 212 12 

739-03 3-17-2000 E.8 <2.1 192 116 7 

739-03 6-02-2000 3.1 E.2 912 369 110 

136-02 9-30-1999 E1.1 E.1 175 166 9 

136-02 1-10-2000 E2.0 E.2 251 244 5 

136-02-R 1-10-2000 E1.5 E.1 247 241 4 

136-02 3-17-2000 E1.1 <2.1 137 122 12 

136-02 6-02-2000 -- -- 257 227 22 

136-03 9-30-1999 E.8 E.1 417 185 19 

136-03 1-10-2000 E1.9 E.2 536 243 13 

136-03 3-17-2000 E1.2 <2.1 714 141 14 

136-03 6-02-2000 E2.2 E.04 799 280 104 

136-04 9-30-1999 E1.4 E.2 281 266 8 

136-04 1-10-2000 E2.2 E.2 327 294 14 

136-04 3-17-2000 E.7 <2.1 121 104 6 

136-04 6-02-2000 -- -- 434 383 38 

136-05 9-30-1999 E1.8 E.2 361 306 18 

136-05 1-10-2000 2.5 E.2 482 312 54 

136-05 3-17-2000 -- -- 3,920 158 335 3,

136-05-R 3-17-2000 E2.2 <2.1 3,100 140 261 2,

136-05 6-02-2000 -- -- 649 525 73 

Quality-control samples—Continued

Deionized water blanks

USGS-MA Laboratory 7-12-1999 <5 <5 -- -- -- 

USGS-MA Laboratory 2-08-2000 <2.2 <.3 -- -- -- 

Ambient-atmospheric blanks

USGS-MA Laboratory 7-12-1999 -- -- -- -- -- 

USGS-MA Laboratory 2-08-2000 -- -- -- -- -- 

Equipment blanks

USGS-MA Laboratory 9-28-1999 <2.2 <2.1 -- -- -- 

USGS-MA Laboratory 6-01-2000 -- -- -- -- -- 

Material blanks

USGS-MA Laboratory 7-29-1998 -- -- -- -- -- 

USGS-MA Laboratory 3-18-1999 <.5 <.5 -- -- -- 
Table 1I. Physical properties and concentrations of fecal-indicator bacteria collected from the inlet and the sump of th

gallon off-line oil-grit separators located along the Southeast Expressway, Boston, Massachusetts 

Station

identifier Date Time Coliform, fecal

(cols/100 mL)

Coliform,

enterococci

(cols./100 mL)

Turbidity,

field

(ntu)

Specifi

conductanc

(uS/cm at 2

136-03 9-30-1999 1110 5,800 14,000 125 141

136-03 9-30-1999 1200 4,200 8,000 110 101

136-03 9-30-1999 1230 2,100 10,000 95 89

136-03 9-30-1999 1300 3,200 8,000 60 114

136-03 1-10-2000 1549 860 25,000 240 603

136-03 1-10-2000 1619 1,170 23,000 310 283

136-03 1-10-2000 1659 420 6,200 165 619

136-03 1-10-2000 1732 60 6,100 140 401

136-03 1-10-2000 1755 297 3,600 90 306

136-03 3-16-2000 2333 50 1,300 290 3,410

136-03 3-17-2000 0055 50 370 150 969

136-03 3-17-2000 0250 10 80 65 383

136-03 3-17-2000 0450 70 350 85 414

136-03 6-02-2000 1845 nd 2,600 130 320

739-03 9-30-1999 1040 2,900 6,500 160 277

739-03 9-30-1999 1107 3,900 8,600 170 179

739-03 9-30-1999 1155 3,100 12,000 140 130

739-03-R 9-30-1999 1156 3,700 9,100 140 130

739-03 9-30-1999 1225 6,900 4,100 120 97

739-03 12-15-1999 0300 2,600 6,800 170 309

739-03 12-15-1999 0445 6,800 5,400 150 191

739-03 12-15-1999 0535 4,400 7,400 160 139

739-03 1-10-2000 1559 1,060 8,000 350 1,910

739-03 1-10-2000 1633 825 6,300 280 1,210

739-03 1-10-2000 1715 240 2,800 150 597

739-03 1-10-2000 1749 310 1,800 100 369

739-03 1-10-2000 1825 120 3,500 65 316

739-03 3-16-2000 2323 20 410 320 2,950

739-03 3-17-2000 0132 10 280 150 932

739-03 3-17-2000 0146 nd 280 65 408

739-03 3-17-2000 0207 70 350 75 650

739-03 3-17-2000 0231 20 1,100 100 12,300

739-03 6-02-2000 1744 nd 1,100 290 507

739-03 6-02-2000 1751 nd 1,100 220 356

739-03-R 6-02-2000 1752 nd 1,200 220 356

739-03 6-02-2000 1910 628 3,500 80 327

136-01 3-17-2000 1500 nd 170 -- 694

739-01 3-17-2000 1535 nd 60 -- 860

Table 1I. Physical properties and concentrations of fecal-indicator bacteria collected from the inlet and the sump of th

gallon off-line oil-grit separators located along the Southeast Expressway, Boston, Massachusetts

[ ̊C, Degrees Celsius; ntu, nephelometric turbidity units; -R, replicate sample; μS/cm, microsiemen per centimeter; col/100 mL, colony per 100 mi

nd, not detected; --, no data]
Quality assurance

Processing blank 9-30-1999 1100 nd 1 -- --

Processing blank 12-15-1999 1100 nd nd -- --

Processing blank 1-10-2000 1830 nd nd -- --

Deionized water 3-17-2000 1420 nd nd -- --

136-03 equip. 3-17-2000 1100 nd nd -- --

739-03 equip. 3-17-2000 1100 nd nd -- --

Processing blank 6-02-2000 0045 nd nd -- --

Table 1I. Physical properties and concentrations of fecal-indicator bacteria collected from the inlet and the sump of th

gallon off-line oil-grit separators located along the Southeast Expressway, Boston, Massachusetts—Continued

Station

identifier Date Time Coliform, fecal(cols/100 mL)

Coliform,

enterococci

(cols./100 mL)

Turbidity,

field

(ntu)

Specifi

conductanc

(uS/cm at 2