U.S. Department of Transportation

Federal Highway

Administration U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2010–5182

Prepared in cooperation with the

Federal Highway Administration and the Massachusetts Department of Transportation

Effectiveness of Catch Basins Equipped with Hoods in 

Retaining Gross Solids and Hydrocarbons in Highway Runoff, 

Southeast Expressway, Boston, Massachusetts, 2008-09
Cover. Photograph of the Southeast Expressway near Tenean Beach in Boston, Massachusetts.
Effectiveness of Catch Basins Equipped 

with Hoods in Retaining Gross Solids 

and Hydrocarbons in Highway Runoff, 

Southeast Expressway, Boston, 

Massachusetts, 2008-09

By Kirk P. Smith

Prepared in cooperation with the Federal Highway Administration and the 

Masachusetts Department of Transportation

Scientific Investigations Report 2010–5182

U.S. Department of the Interior

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

KEN SALAZAR, Secretary

U.S. Geological Survey

Marcia K. McNutt, Director

U.S. Geological Survey, Reston, Virginia: 2010

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reproduce any copyrighted materials contained within this report.

Suggested citation:

Smith, K. P., 2010, Effectiveness of catch basins equipped with hoods in retaining gross solids and hydrocarbons 

in highway runoff, Southeast Expressway, Boston, Massachusetts, 2008–09: U.S. Geological Survey Scientific 

Investigations Report 2010–5182, 23 p., at http://pubs.usgs.gov/sir/2010/5182.
iii

Acknowledgments

The author expresses his gratitude to Henry L. Barbaro and Alex J. Murray of the Massachusetts 

Department of Transportation, Environmental Services Division; Gene W. Parker and Chad R. 

Wagner of the U.S. Geological Survey; Thomas M. Maguire of the Massachusetts Department 

of Environmental Protection; Vincent P. Vignaly, P.E., of the Massachusetts Department of 

Conservation and Recreation; and David C. Nyman, P.E., of Comprehensive Environmental 

Incorporated, Marlborough, Massachusetts, for providing valuable review comments on the 

manuscript. The author also thanks Brett Loosian, Lee J. Devereaux, and Thomas R. Lemiesz 

of the Massachusetts Department of Transportation District 4 for providing logistical support, 

including site selection, highway catch-basin maintenance, and periodic traffic control. 

Massachusetts Department of Transportation Disclaimer

The information contained in this report was compiled for the use of the public and the 

Massachusetts Department of Transportation. Conclusions contained herein are based upon 

the research data obtained and the expertise of the researchers, and are not necessarily to be 

construed as the official view or policies of the Massachusetts Department of Transportation or 

the Federal Highway Administration. This report does not constitute a standard, specification, 

or regulation. 
iv

This page has been left blank intentionally.
v

Contents

Abstract...........................................................................................................................................................1

Introduction ....................................................................................................................................................2

Purpose and Scope ..............................................................................................................................2

Study area..............................................................................................................................................2

Site Selection .................................................................................................................................................2

Methods...........................................................................................................................................................4

Site Preparation and Equipment Installation ...................................................................................4

Collection and Analysis of Continuous Water-Level and Rainfall Data.......................................9

Collection and Analysis of Samples of Gross Solids ...................................................................11

Collection and Analysis of Samples of Oil and Grease and Total 

Petroleum Hydrocarbons ....................................................................................................13

Effectiveness of Catch-Basin Hoods .......................................................................................................18

Retaining Gross Solids.......................................................................................................................18

Retaining Oil and Grease and Total Petroleum Hydrocarbons ...................................................21

Summary........................................................................................................................................................23

References Cited..........................................................................................................................................24

Figures

1. Map showing study area with hooded catch basins, Southeast Expressway in

Boston, Massachusetts...............................................................................................................3

2. Schematic diagram of a deep-sump off-line hooded catch basin and location of the

weir and debris collection structure .........................................................................................4

3. Photograph of a grate installed on a catch basin along the Southeast Expressway

in Boston, Massachusetts, at start of the study......................................................................5

4. Photograph of a grate installed on a catch basin along the Southeast Expressway

in Boston, Massachusetts, during resurfacing of the highway............................................5

5. Photograph showing A, standard cast-iron hood typically used along the Southeast

Expressway, B, an Eliminator hood, and C, a Snout hood, which were tested along

the Southeast Expressway in Boston, Massachusetts, 2008................................................6

6. Photograph showing a typical debris collection structure attached to the catchbasin outlet pipe along the Southeast Expressway in Boston, Massachusetts, 2008 ......8

7. Photograph showing seed materials added to the sump of catch basin 130 along

the Southeast Expressway in Boston, Massachusetts, 2008................................................9

8. Photograph showing floatable materials collected in a net from catch basin 739 on

the Southeast Expressway in Boston, Massachusetts, 2008..............................................14

9. Photograph showing a vacuum truck emptying the entire contents of a single catch

basin on a tarp prior to sample processing............................................................................15

10. Photograph showing a vertical water-column sample being collected with a Teflon

dip-stick sampler from catch basin 739 on the Southeast Expressway in Boston,

Massachusetts, 2009..................................................................................................................17

11. Pie chart showing the distribution of highway solids collected from the outfalls of

six deep-sump off-line hooded catch basins along the Southeast Expressway in

Boston, Massachusetts, May through November 2008 .......................................................19
vi

12. Box plot showing the distribution of concentrations of oil and grease, and total

petroleum hydrocarbons, measured in composite samples, collected in a prior U.S.

Geological Survey study (Smith 2002), of highway runoff discharged from

deep-sump off-line catch basins containing cast-iron hoods and those measured in

composite samples of highway runoff discharged from a deep-sump off-line catch

basin equipped with an Eliminator hood collected in this study (2009) along the same 

section of road on the Southeast Expressway in Boston, Massachusetts .....................22

Tables

1. Descriptions of six deep-sump off-line hooded catch basins monitored along the

Southeast Expressway in Boston, Massachusetts.................................................................6

2. Rainfall and runoff statistics for discrete sampling periods for sites 131, 136, and

739 along the Southeast Expressway, in Boston, Massachusetts, 2008...........................10

3. Mass of gross highway solids greater than 0.25 inches in diameter collected from

the outlets of six deep-sump off-line hooded catch basins fitted with hoods along

Southeast Expressway, in Boston, Massachusetts, 2008....................................................11

4. Mass and distribution of gross highway solids collected from the outlets of six

deep-sump off-line hooded catch basins along the Southeast Expressway in

Boston, Massachusetts, 2008...................................................................................................12

5. Total mass of highway solids collected from various points in the highway drainage

system and the effectiveness for the six deep-sump off-line hooded catch basins in

retaining gross solids along Southeast Expressway, in Boston, Massachusetts. .........16

6. Recovery of seed materials from the debris-collection structures at the outlets of

the six deep-sump off-line hooded catch basins and storm statistics for each

period between sample collections along Southeast Expressway, in Boston,

Massachusetts, 2008..................................................................................................................20

7. Concentrations of oil and grease, and total petroleum hydrocarbons collected from

the water surface in sumps of five deep-sump off-line hooded catch basins along

the Southeast Expressway, in Boston, Massachusetts, 2008–09.......................................21

8. Concentrations of oil and grease, and total petroleum hydrocarbons, in

flow-weighted samples of highway runoff collected from the outlet of catch basin

739 and in a vertical-profile sample collected in the sump of catch basin 739 along

the Southeast Expressway, in Boston, Massachusetts, 2008–09.......................................22
vii

Conversion Factors, Data, and Abbreviations

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

inch (in.) 25.4 millimeter (mm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

Acre 4,047 square meter (m2

)

square foot (ft2

) 0.09290 square meter (m2)

square inch (in2

) 6.452 square centimeter (cm2)

Volume

cubic foot (ft3

) 0.02832 cubic meter (m3) 

Flow rate

cubic foot per second (ft3

/s) 0.02832 cubic meter per second (m3/s)

inch per hour (in/h) 0 .0254 meter per hour (m/h)

Mass

ounce, avoirdupois (oz) 28.35 gram (g) 

Horizontal coordinate information is referenced to North American Datum of 1983 (NAD 83).
This page has been left blank intentionally.
Effectiveness of Catch Basins Equipped with Hoods in 

Retaining Gross Solids and Hydrocarbons in Highway 

Runoff, Southeast Expressway, Boston, Massachusetts, 

2008–09

By Kirk P. Smith

Abstract

Stormwater mobilizes litter and other debris along the 

roadway where it is transported to the highway drainage 

systems. Initial treatment for stormwater runoff typically is 

provided by catch basins in highway settings. Modification of 

catch basins to include hoods that cover the catch-basin outlet 

is intended to enhance catch-basin performance by retaining 

floatable debris and various hydrophobic organic compounds 

that tend to float on the water surface within the sump of the 

catch basin.

The effectiveness of six deep-sump off-line catch basins 

equipped with hoods in reducing the mass of gross solids 

greater than 0.25 inches in diameter and concentrations of 

oil and grease (OG) and total petroleum hydrocarbons (TPH) 

was examined along the Southeast Expressway, in Boston, 

Massachusetts. Two deep-sump catch basins were equipped 

with cast-iron hoods. Three were equipped with molded plastic 

hoods, known as an Eliminator, and a single catch basin was 

equipped with a fiberglass anti-siphoning hood, known as 

a Snout. Samples of gross solids greater than 0.25 inches 

in diameter, excluding gravel and metallic materials, were 

routinely collected for a 6-month period from a collection 

structure mounted at the end of each catch-basin outlet pipe. 

After about 6 months, all floatable, saturated low-density and 

high-density solids were removed from each catch basin. In 

addition to the collection of samples of gross solids, samples 

of sump water from five catch basins and flow-weighted 

composite samples of stormwater from the outlet of one catch 

basin were collected and analyzed for concentrations of OG 

and TPH.

A mass balance approach was used to assess the 

effectiveness of each catch basin equipped with a hood in 

retaining gross solids. The effectiveness of the deep-sump 

catch basins fitted with one of three types of hoods in retaining 

gross solids ranged from 27 to 52 percent. From 45 to 

90 percent of the gross solids collected from the catch-basin 

sumps were composed of materials made of high-density 

plastics that did not float in water, and as a result, the effect 

that the catch-basin hoods had on these materials likely was 

marginal. The effectiveness for the deep-sump hooded catch 

basins, excluding the mass of high-density materials identified 

in the solids collected from the outlet pipe and the sump of the 

catch basins, ranged from 13 to 38 percent. The effectiveness 

for each catch basin, based solely on the material that 

remained floating at the end of the monitoring period, was less 

than 11 percent; however, these values likely underestimate 

the effectiveness of the hooded catch basins because much of 

the low-density material collected from the sumps may have 

been retained as floatable material before it was saturated and 

settled during non-storm conditions. The effectiveness of the 

catch basins equipped with hoods in reducing gross solids was 

not greatly different among the three types of hoods tested in 

this study.

Concentrations of OG and TPH collected from the water 

surface of the catch-basins varied from catch basin to catch 

basin and were similar to concentrations of flow-weighted 

composite samples collected during storms. Comparisons 

indicate concentrations of OG and TPH in flow-weighted 

composite samples collected at the outlet of a catch basin 

equipped with an Eliminator hood were not substantially 

different from concentrations of the respective constituents in 

flow-weighted composite samples collected during a previous 

study from catch basins containing cast-iron hoods in the 

same study area. The similarity between these flow-weighted 

concentrations and the concentrations of the respective 

constituents in a vertical profile sample collected from the 

catch-basin sump indicates that OG and TPH are emulsified 

in the sump of each catch basin during storms and circumvent 

the hoods. 
2 Effectiveness of Catch Basins Equipped with Hoods in Retaining Gross Solids and Hydrocarbons in Runoff, Boston, Massachusetts, 2008–09

Introduction 

Natural and anthropogenic debris commonly accumulate 

along the edges of highways. These materials are mobilized 

during rain storms and wash into highway-drainage systems 

where they are ultimately discharged onto the toe of the 

highway embankments or to receiving water bodies. Debris, 

including litter and various fragments from damaged or 

deteriorating automobiles, can adversely affect receiving 

water quality and may result in the failure of a water 

body to comply with Massachusetts surface-water-quality 

standards (Massachusetts Department of Environmental 

Protection, 2007). 

Deep-sump catch basins provide primary treatment for 

highway runoff along the Southeast Expressway in Boston, 

Massachusetts. Catch-basin hoods are intended to enhance 

catch-basin performance by retaining floatable debris, 

including floatable oil, grease, and petroleum hydrocarbons, 

at the water surface within the sump of the catch basin. Catch 

basins that do not contain hoods have no physical means of 

retaining floatable solids in the catch basin sump. Little or 

no floatable debris were observed in a survey of more than 

40 catch basins that were not equipped with hoods on parts 

of Route 119, Route 2, Route 8, Interstate 95, Interstate 

190, Interstate 195, and Interstate 495 in Massachusetts. In 

one study (U.S. Environmental Protection Agency, 1999a), 

catch basins equipped with hoods were reported to retain 

approximately 85 percent of the litter delivered to a New 

York City sewer system, whereas unhooded catch basins 

retained 30 percent of the litter. Recent evidence from a 

best management practice study (Smith, 2002) along the 

Southeast Expressway (Interstate 93), however, indicates 

that the actual benefit of hoods in deep-sump catch basins 

is limited for highway settings. At the conclusion of the 

14-month study targeting a deep-sump catch basin containing 

a cast-iron hood, the structure was virtually free of litter 

and other debris, although large amounts of these materials 

were noted not only in the downstream water-quality inlet of 

the catch basin under study but in four other water-quality 

inlets located along the Southeast Expressway that also 

received discharge from deep-sump catch basins with hoods. 

Though catch-basin hoods may work well for large floatable 

debris (intact bottles and Styrofoam cups for example), 

submerged debris may pass under the hoods. Catch-basin 

hoods also can obstruct catch-basin maintenance activities 

(ASCG Incorporated, 2005), affecting the removal of sump 

materials and potentially damaging the hood itself. The U.S. 

Geological Survey (USGS), in cooperation with the Federal 

Highway Administration and the Massachusetts Department 

of Transportation (Massachusetts DOT), investigated the 

effectiveness of catch basins equipped with three types of 

hoods to retain gross solids, oil and grease (OG), and total 

petroleum hydrocarbons (TPH). 

Purpose and Scope

This report describes the effectiveness for deep-sump 

offline catch basins equipped with three types of hoods 

along the Southeast Expressway for the purpose of retaining 

gross highway solids (excluding gravel and metal materials), 

OG, and TPH. The methods used for collection of data also 

are described. The effectiveness of these structural best 

management practices is based on highway-runoff data 

collected from May 2008 through April 2009.

Study area

The study area is composed of two northbound sections 

of the Southeast Expressway near the Neponset River and 

Tenean Beach in Boston, Massachusetts (fig. 1). Within the 

study area, deep-sump catch basins provide primary treatment 

for highway runoff. Highway runoff collected by the catch 

basins either is discharged to the embayment near Tenean 

Beach or infiltrates in the ground at the toe of the highway 

embankment. The two segments of highway that contain 

the hooded catch basins monitored in this study are about a 

mile apart.

Catch basins are circular concrete containers below the 

highway with steel grates at the pavement surface (fig. 2). 

The catch basins monitored along the Southeast Expressway 

have sumps (that is, storage area below the outlet pipe) that 

are 4 ft deep and are termed deep-sump catch basins. The 

catch basins do not contain curb inlets, and the grates cover 

the entire inlet. The initial catch-basin grates (fig. 3) contained 

2 rows of 10 open parallel slits (1.2 in. by 9.4 in.); however, 

the highway was resurfaced about halfway through the study 

period (August), and the grates were replaced. The new grates 

(fig. 4) contain 36, 2.4 in. by 2.4 in. square openings. Prior to 

this study, each catch basin was equipped with a hinged castiron hood which fit over the catch-basin sump outlet. The hood 

loosely encapsulates the outlet opening and extends about 

0.5 ft below the bottom of the outlet. As part of this study, 

cast-iron hoods were removed from four catch basins, and 

hoods of more recent designs were installed according to the 

manufacturers’ specifications. 

Site Selection 

Six catch basins along the Southeast Expressway 

between Tenean Beach and the Neponset River in Boston, 

Massachusetts, were selected for monitoring and for collection 

of gross solids. In this study, gross solids refers to natural 

organic matter (leaves, sticks, and bark), litter, plastic and 

fiberglass automobile components, and other non-descriptive 

debris greater than 0.25 in. in diameter (excluding gravel, and 

metallic and asphalt particles). The selection of catch basins 

was made on the basis of the ability to define the drainage area 

for each catch basin, to mount a debris-collection structure 
Site Selection 3

Southeast

Expressway

U.S. Route

1

Interstate

93

0 0.5 MILE

0

Orthophoto source MassGIS, EOEA, 1995

71°03' 71°02'30"

42°18'30"

42°17'

0.25

0.25 0.5 KILOMETER

136

739

742

137

130

131

739 Site of hooded catch basin 

 and number 

EXPLANATION

STUDY AREA

MAP AREA SHOWN

0 50 KILOMETERS

0 50 MILES 

MASSACHUSETTS

BOSTON

BOSTON

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

SOMERVILLE

CAMBRIDGE

BROOKLINE

41°30'

70°00'

71°00' 73°00'

42°30'

Figure 1. Study area with hooded catch basins, Southeast Expressway in Boston, Massachusetts.
4 Effectiveness of Catch Basins Equipped with Hoods in Retaining Gross Solids and Hydrocarbons in Runoff, Boston, Massachusetts, 2008–09

Gravel, sand, and other 

high-density debris

4 feet

4 feet

Weir

Hood

Grate

Debris collection structure

Grate Highway

pavement

Fill embankment

Stormwater pipe

Stormwater pipe

Edge of road

Point of zero flow

floatable debris

Deep-sump

hooded

catch basin

Figure 2. Schematic diagram of a deep-sump off-line hooded catch basin and location of the weir 

and debris collection structure.

to the catch-basin discharge pipe, and to collect samples of 

highway runoff for analysis of concentrations of OG and TPH. 

Only off-line catch basins were selected because they do not 

receive additional flow from other catch basins. The selection 

of sites was subject to the availability of locations away from 

roadway traffic and near the drainage outfalls. Highway 

construction plans detailing the drainage systems provided by 

the Massachusetts DOT were utilized for initial screening of 

potential catch basins.

On the basis of the previously defined criteria, six deepsump, off-line catch basins were selected for monitoring gross 

highway solids (table 1). The cast-iron hoods (fig. 5A) were 

left installed in two catch basins (sites 131 and 742). Three 

molded plastic hoods, known as Eliminator hoods (fig. 5B), 

were installed at monitoring sites 136, 137, and 739, and 

a single fiberglass anti-siphoning hood, known as a Snout 

(fig. 5C), was installed at monitoring site 130. The design of 

the Snout hood requires the device to be mounted flush with 

the catch-basin wall. Unfortunately, the interior walls of many 

of the catch basins were deteriorated, and sub-drain pipes 

often protruded near the catch basin outlets, preventing the 

device from sealing properly. These common circumstances 

prevented the mounting of the Snout hood in all but one of the 

catch basins.

Methods

The methodology includes site preparation, installation of 

monitoring devices, and collection and analysis of continuousmonitor data, and collection of samples of gross solids and 

water from the catch basins.

Site Preparation and Equipment Installation

The six catch basins were cleaned with a vacuum truck 

by the Massachusetts DOT on May 1 and 14, 2008, prior to 

the installation of the new hoods and the collection of gross 

solids. A weir was installed in the outlet pipe of the catch 
Methods 5

Figure 3. Grate installed on a catch basin along the Southeast Expressway in Boston, Massachusetts, at start of the study.

Figure 4. Grate installed on a catch basin along the Southeast Expressway in Boston, Massachusetts, during resurfacing of 

the highway.
6 Effectiveness of Catch Basins Equipped with Hoods in Retaining Gross Solids and Hydrocarbons in Runoff, Boston, Massachusetts, 2008–09

Table 1. Descriptions of six deep-sump off-line hooded catch basins monitored along the Southeast Expressway in 

Boston, Massachusetts.

[USGS, U.S. Geological Survey; °, degree; ′, minute; ′′, seconds]

USGS 

Streamgage 

number

Site 

designation Latitude Longitude Drainage area (acres) Curb mile Catch-basin hood type

421751071024801 130 42°17′51′′ 71°02′48′′ 0.25 0.08 Snout

421749071024701 131 42°17′49′′ 71°02′47′′ 0.10 0.03 Cast-iron

421745071024506 136 42°17′45′′ 71°02′45′′ 0.19 0.07 Eliminator

421743071024401 137 42°17′43′′ 71°02′43′′ 0.18 0.06 Eliminator

421647071024705 739 42°16′47′′ 71°02′47′′ 0.08 0.03 Eliminator

421649071024801 742 42°16′49′′ 71°02′48′′ 0.10 0.03 Castiron

A

Figure 5. A, standard cast-iron hood typically used along the Southeast Expressway, B, an Eliminator hood, and C, a Snout hood, 

which were tested along the Southeast Expressway in Boston, Massachusetts, 2008.
Methods 7

B

C

Figure 5. A, standard cast-iron hood typically used along the Southeast Expressway, B, an Eliminator hood, and C, a Snout hood, 

which were tested along the Southeast Expressway in Boston, Massachusetts, 2008.
8 Effectiveness of Catch Basins Equipped with Hoods in Retaining Gross Solids and Hydrocarbons in Runoff, Boston, Massachusetts, 2008–09

basins (fig. 2) located on the right-most northbound lane on 

the Southeast Expressway at sites 131, 136, and 739. The 

monitoring site at catch basin 739 was configured to measure 

and record rainfall, as well as the water level in the outlet of 

the catch basin. This monitoring site also was configured to 

collect water samples at the outlet of the catch basin for the 

analysis of concentrations of OG and TPH. Programmable 

water-level sensors also were installed in the catch basin 

outlet at sites 131 and 136. The Eliminator hoods (fig. 5B) and 

the single Snout hood (fig. 5C) were installed after the catch 

basins were cleaned. Cast-iron hoods were left in place at the 

remaining two catch basins. Debris collection structures were 

installed at each of the six monitoring sites after the catch 

basins were cleaned (fig. 2). These cylindrical devices (fig. 6) 

were constructed from 0.25-in. galvanized mesh screen. The 

screen was sandwiched between two plywood rings at the 

open end of the device. These rings were secured to the end of 

each pipe with bolts and wing nuts. 

Following the installation of the new hoods and the 

occurrence of one or more storms, two types of floatable 

seed material were added to each of the catch basins (fig. 7) 

once the water in each catch basin resumed a normal static 

level. These materials included small sealed zip-lock bags 

(4 x 6 inches) with a label inside and small plastic tubes that 

were slightly larger in diameter than a cigarette or pen. These 

seed materials were quantified after each sample collection 

and again at the end of the field study to help determine 

the effectiveness of each hood in retaining standardized 

floatable materials.

Massachusetts, 2008.

Figure 6. A typical debris collection structure attached to the catch-basin outlet pipe along the Southeast Expressway in Boston, 
Methods 9

Figure 7. Seed materials added to the sump of catch basin 130 along the Southeast Expressway in Boston, Massachusetts, 2008.

Collection and Analysis of Continuous 

Water-Level and Rainfall Data

Water-level sensors were installed behind a weir mounted 

in the outlet pipe of the catch basins at sites 131, 136, and 

739. The monitoring system at site 739 was programmed to 

measure water level and rainfall every minute. Baseline data 

(that is, data that are recorded regardless of the state of runoff) 

for water level and rainfall were recorded every 2 hours. 

Water level and rainfall were recorded on a 1-minute basis 

whenever the water level behind the weir in the catch basin 

outlet pipe was greater than the point of zero flow or when 

rain was measured. These data were collected from May 2008 

through April 2009. The submersible monitoring device at 

site 136 also measured the water level every minute; however, 

the device recorded values on a 1-minute basis whenever a 

change in water level in the catch basin outlet pipe exceeded 

a water-level threshold of 0.02 ft. Baseline measurements at 

site 136 were recorded every 15 minutes. Data for site 136 

were collected though August 2008. Similar data also were 

collected at site 131 for one week in June 2008. 

Instantaneous flow was estimated on the basis of the 

water-level measurements and a level-discharge relation for 

each weir for all storms with available data. Storm statistics, 

such as total runoff, flow duration, and peak flow, were 

calculated from these instantaneous values for sites 131, 

136, and 739 (table 2). Total runoff and flow duration for 

these catch basins for each sampling period was calculated 

by summing the discrete storm values for each statistic. The 

highest peak flow was selected where the sampling period 

included more than one storm. Total rainfall and maximum 

1-hour rainfall intensity also were computed on the basis of 
10 Effectiveness of Catch Basins Equipped with Hoods in Retaining Gross Solids and Hydrocarbons in Runoff, Boston, Massachusetts, 2008–09

Table 2. Rainfall and runoff statistics for discrete sampling periods for sites 131, 136, and 739 along the 

Southeast Expressway, in Boston, Massachusetts, 2008.

[mm/dd, month/day; --, data type was not collected or is not available at this site; ft3, cubic feet; s, second]

Sampling 

period 

end date 

(mm/dd)

Site 

designation

Rainfall statistics Runoff statistics

Total 

rainfall 

(inches)

Maximum 

hourly 

rainfall 

(inches/hour)

Peak Flow, 

ft3/s

Total runoff 

duration, 

in hours

Total runoff 

volume, ft3

05/14 739 0.24 0.07 0.03 6.9 737

05/17 739 0.78 0.16 0.08 14.0 448

05/28 739 0.20 0.12 0.04 2.6 73

06/05 739 0.56 0.14 0.04 3.0 187

06/17 739 1.03 0.25 0.10 5.3 618

06/24 739 0.12 0.08 0.03 0.4 10

07/02 739 0.89 0.66 1.21 2.4 1,770

07/11 739 0.72 0.45 0.57 3.3 1,650

07/21 739 0.87 0.39 1.21 4.8 3,990

07/30 739 4.38 1.33 1.21 27.5 12,700

08/04 739 1.06 0.73 1.21 5.6 1,750

08/13 739 1.63 0.37 0.62 11.3 1,170

08/28 739 0.46 0.13 0.29 58.7 2,510

09/09 739 2.10 0.54 0.10 17.9 3,690

09/24 739 0.83 0.3 0.69 7.3 684

09/30 739 3.85 0.48 0.50 46.6 11,600

11/03 739 1.44 0.29 0.95 15.5 5,820

06/24 131 -- -- 0.31 0.9 222

05/14 136 -- -- 0.00 2.5 2

05/17 136 -- -- 0.03 13.3 177

05/28 136 -- -- 0.13 2.8 119

06/05 136 -- -- 0.01 2.4 41

06/17 136 -- -- 0.12 5.0 566

06/24 136 -- -- 0.18 0.6 139

07/02 136 -- -- 1.20 3.1 5,310

07/11 136 -- -- 1.20 7.1 16,200

07/21 136 -- -- 1.19 5.1 14,900

07/30 136 -- -- 1.20 35.9 12,200

08/13 136 -- -- 0.33 7.7 1,310

08/28 136 -- -- 0.89 9.1 661
Methods 11

data collected at site 739. Total rainfall includes all measured 

rain during each sampling period. The highest maximum 

1-hour rainfall intensity was selected where the sampling 

period included more than one storm. These statistics are later 

evaluated in regard to the mass of gross solids collected at the 

outlet pipe of each catch basin to assess the circumstances that 

affect the performance of each catch-basin hood.

For the previous sites, runoff volumes estimated on the 

basis of drainage area and rainfall volume correlate poorly 

with measured volumes of runoff. Measured volumes of 

runoff often were substantially larger than volumes of runoff 

estimated. In part, this is explained by the spatial location of 

the sites and potential differences in the distribution of rainfall 

over the study area. It is also likely that construction activities 

on the roadway affected drainage patterns where water 

bypassed upgradient catch basins and entered the catch basins 

at sites 136, 137, and 739 that were centered on low points 

along the roadway. As a result, the effective drainage area for 

these sites for some storms may actually be larger than those 

listed in table 1.

Collection and Analysis of Samples of 

Gross Solids 

Gross solids were retrieved about every week from each 

collection structure (fig. 6) at the end of a storm or series of 

storms. Solids removed from each device were placed in bags 

and transported to the USGS Massachusetts Water Science 

Center. Seed materials were removed from the mass of solids 

and tabulated. The mass of captured material from each catchbasin outlet was determined by drying the contents (less any 

seed material) at 105 degrees Celsius (o

C) to a constant weight 

in a laboratory oven over a period of several days (table 3). 

The contents of each sample of dried solids were identified 

by visual inspection. Identifiable materials were placed in 

general categories, such as cigarette butts, plastics (wrappers, 

Styrofoam, and other plastics), and natural vegetation 

matter. The net weight for each category of each sample was 

measured and recorded to the nearest 0.01 milligram (table 4). 

Once all samples were processed, the individual samples of 

Table 3. Mass of gross highway solids greater than 0.25 inches in diameter collected from the outlets of six deep-sump off-line 

hooded catch basins fitted with hoods along Southeast Expressway, in Boston, Massachusetts, 2008. 

[Clean, indicates catch basin was cleaned on this date; mm/dd, month/day; --, no data available]

Sampling 

period 

end date 

(mm/dd)

Mass of solids collected from catch basin outlets, in grams

Site designation and hood type

130 

(Snout)

131 

(Cast iron)

136 

(Eliminator)

137 

(Eliminator)

739 

(Eliminator)

742 

(Cast iron)

05/01 -- -- Clean Clean Clean Clean

05/14 Clean Clean 0 0 0 0

05/17 1.80 2.47 0.00 2.08 0.00 10.54

05/28 0.00 4.76 0.00 0.24 0.00 0.00

06/05 0.00 0.21 0.55 0.00 0.00 0.00

06/17 3.71 7.21 0.45 2.58 0.24 5.79

06/24 0.00 37.90 1.10 13.75 0.00 0.00

07/02 4.79 91.20 817.58 307.93 542.63 242.72

07/11 1.14 13.76 327.37 5.44 101.23 90.16

07/21 303.95 311.25 617.26 23.47 264.28 54.30

07/30 86.85 0.00 194.24 0.00 403.81 108.69

08/04 44.29 182.90 -- 197.97 424.54 115.00

08/13 7.17 39.69 25.41 6.13 47.05 25.67

08/28 0.28 1.49 0.00 0.00 14.73 1.36

09/09 6.23 43.94 14.29 3.32 177.61 49.80

09/24 4.59 33.03 7.73 3.24 179.91 131.88

09/30 13.87 40.20 28.43 1.91 85.72 82.13

11/03 19.46 45.22 36.68 36.68 171.34 175.47

Total 498 855 2,071 605 2,413 1,094
12 Effectiveness of Catch Basins Equipped with Hoods in Retaining Gross Solids and Hydrocarbons in Runoff, Boston, Massachusetts, 2008–09

Table 4. Mass and distribution of gross highway solids collected from the outlets of six deep-sump off-line hooded catch basins 

along the Southeast Expressway in Boston, Massachusetts, 2008. 

[--, no data available; mm/dd, month/day; Cig., cigarette butts; Plastic, both high- and low-density plastic materials; Veg., natural vegetation including grass, 

leaves, bark, and sticks]

Sampling 

period 

end date 

(mm/dd)

Mass of solids, in grams

Site designation and type of catch-basin hood

130 (Snout) 131 (Cast iron) 136 (Eliminator)

Cig. Plastic Veg. Cig. Plastic Veg. Cig. Plastic Veg.

05/14 -- -- -- -- -- -- 0.00 0.00 0.00

05/17 0.19 1.56 0.05 0.40 0.02 2.05 0.00 0.00 0.00

05/28 0.00 0.00 0.00 2.22 2.04 0.51 0.00 0.00 0.00

06/05 0.00 0.00 0.00 0.21 0.00 0.00 0.00 0.00 0.55

06/17 0.00 3.49 0.22 0.02 3.05 4.13 0.00 0.00 0.45

06/24 0.00 0.00 0.00 5.48 9.23 23.19 0.00 0.34 0.76

07/02 0.83 1.63 2.33 5.82 11.49 73.89 27.15 54.29 736.14

07/11 0.00 0.26 0.88 2.03 1.62 10.11 14.66 6.98 305.72

07/21 8.85 53.29 241.81 3.51 14.08 293.65 35.35 134.10 447.81

07/30 18.37 5.56 62.92 0.00 0.00 0.00 10.58 14.76 168.90

08/04 3.33 17.50 23.46 19.08 37.90 125.93 -- -- --

08/13 2.05 2.22 2.90 6.31 4.83 28.55 2.74 12.61 10.06

08/28 0.07 0.07 0.14 0.04 0.05 1.41 0.00 0.00 0.00

09/09 0.39 0.27 5.57 3.08 8.56 32.30 0.63 2.61 11.05

09/24 1.26 1.13 2.21 4.02 14.40 14.61 1.04 4.02 2.67

09/30 0.14 4.02 9.70 6.99 21.44 11.77 1.22 0.99 26.22

11/03 2.47 7.90 9.09 6.02 2.23 36.97 1.75 11.25 23.68

Total 37.96 98.90 361.3 65.22 130.9 659.1 95.13 241.9 1734

plastic materials were combined for each catch basin and 

placed in a bucket of tap water at room temperature for a 

period of about 15 minutes to separate low-density plastic 

materials from high-density plastic materials. High-density 

plastics materials were retrieved from the bottom of each 

bucket, and the mass of these plastics was determined as 

described previously.

At the end of the solid-monitoring phase of the study, 

all floatable debris were removed with a net (fig. 8) from 

each catch basin, except for the catch basin at site 131, which 

did not have standing water in the sump. The remaining 

sump contents were removed one catch basin at a time with 

a vacuum truck. The sump deposits beneath the hoods were 

removed manually because there was insufficient room in the 

catch basin to angle the intake for the vacuum pipe under the 

hoods. The tank on the vacuum truck was cleaned prior to each 

use. After removing the sump contents of each catch basin, 

the solids were emptied from the vehicle on a large clean tarp 

at a nearby service depot (fig. 9). This step was repeated for 

each catch basin. All solid materials greater than about 0.25 in. 

in diameter were separated from the smaller gravel and 

asphalt materials by wet sieving. Solids, excluding large rock, 

asphalt, and metallic materials, were placed in plastic bags and 

transported to the USGS Massachusetts Water Science Center. 

Metallic items consisted of studs, nuts, and other heavy, dense 

items that were too dense to float and thus were treated like 

gravel and omitted from analysis. The mass of the floatable 

material collected with the net and the mass of the gross solids 

recovered from the sump material were determined by drying 

the contents at 105o

C to a constant weight in a laboratory 

oven over a period of several days (table 5). Since many of 

the identifiable objects collected in the net were similar to 
Methods 13

Table 4. Mass and distribution of gross highway solids collected from the outlets of six deep-sump off-line hooded catch basins 

along the Southeast Expressway in Boston, Massachusetts, 2008. 

[--, no data available; mm/dd, month/day; Cig., cigarette butts; Plastic, both high- and low-density plastic materials; Veg., natural vegetation including grass, 

leaves, bark, and sticks]

Sampling 

period 

end date 

(mm/dd)

Mass of solids, in grams

Site designation and type of catch-basin hood

137 (Eliminator) 739 (Eliminator) 742 (Cast iron)

Cig. Plastic Veg. Cig. Plastic Veg. Cig. Plastic Veg.

05/14 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

05/17 0.37 0.05 1.66 0.00 0.00 0.00 0.96 2.70 6.88

05/28 0.20 0.04 0.00 0.00 0.00 0.00 0.00 0.00 0.00

06/05 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

06/17 2.21 0.26 0.11 0.24 0.00 0.00 0.15 0.56 5.08

06/24 0.66 8.45 4.64 0.00 0.00 0.00 0.00 0.00 0.00

07/02 1.64 7.92 298.37 13.25 44.87 484.51 11.40 12.87 218.46

07/11 0.54 0.00 4.90 5.23 6.91 89.09 6.53 10.48 73.14

07/21 1.15 4.13 18.20 14.42 22.74 227.12 11.24 23.59 19.47

07/30 0.00 0.00 0.00 36.75 71.03 296.03 16.68 12.67 79.34

08/04 9.02 130.46 58.49 28.86 90.08 305.60 13.91 18.09 83.00

08/13 0.94 2.39 2.80 5.17 6.04 35.84 3.70 3.35 18.62

08/28 0.00 0.00 0.00 0.94 0.74 13.05 0.76 0.00 0.61

09/09 0.00 1.25 2.07 3.04 50.24 124.33 5.53 3.74 40.53

09/24 0.31 1.29 1.65 3.17 63.19 113.55 7.96 17.01 106.91

09/30 0.01 0.61 1.29 2.83 4.38 78.52 3.61 2.60 75.92

11/03 2.01 0.97 33.71 4.94 32.21 134.19 20.38 39.00 116.09

Total 19.04 157.8 427.9 118.8 392.4 1902 102.8 146.7 844.0

what was observed in the sump material, the dried contents 

of the sump material were placed in a large bucket of water at 

room temperature for a period of about 15 minutes to separate 

potential floatable objects from high-density objects that were 

not buoyant under such conditions.

Collection and Analysis of Samples of Oil and 

Grease and Total Petroleum Hydrocarbons 

Water samples were collected at the surface of the water 

column in the sump of each catch basin (except for site 

131 which had no standing water in the sump at the time of 

sample collection) in the fall of 2008 at the end of the solidmonitoring phase of the study and again in the spring of 

2009. These samples were collected by partially submersing 

the opening of a precleaned bottle beneath the surface of 

the sump water at each catch basin. A sample of the water 

column also was collected from the catch basin at site 739 

in April 2009 using a Teflon dip-stick sampler (fig. 10). The 

dip-stick sampler consisted of a 7-ft Teflon pipe with a valve 

containing four 0.25-in. holes set 90 degrees from each other 

at the bottom and a closure at the top. The sample of water 

was collected by slowly lowering the device from the water 

surface to the sump floor at which point the top of the device 

was sealed, the sampler was removed, and the contents were 

dispensed directly into a precleaned bottle. This process was 

continued until sufficient water was collected for analysis. 

Finally, five flow-weighted composite samples of highway 

runoff were collected from the outlet of catch basin 739 from 

December 2008 to April 2009.

Flow-weighted composite samples were collected with 

an automatic sampler under datalogger control. The sampler 

intake line was mounted in a sloping manner to allow for 
14 Effectiveness of Catch Basins Equipped with Hoods in Retaining Gross Solids and Hydrocarbons in Runoff, Boston, Massachusetts, 2008–09

Figure 8. Floatable materials collected in a net from catch basin 739 on the Southeast Expressway in Boston, Massachusetts, 2008.

the complete purging and draining of sample water between 

samples. The sampler intake was fixed to a static mixer 

to provide a secure mount for the sampler intake, reduce 

transport velocity, and to provide agitation to produce a 

sample that represented the average quality of the runoff 

(Smith, 2002). Sampler intakes were oriented in a horizontal 

and downstream direction. Each automatic sampler was 

configured to hold one 20-liter Teflon-lined plastic bottle. 

The Teflon lining consisted of a double-wall Teflon pouch 

constructed in a clean room without the use of glue or 

adhesives. The sampler’s intake lines consisted of 0.5-in. 

Teflon tubing attached to silicon pump-head tubing with a 

custom made Teflon discharge tube. The sampler tubing was 

cleaned, and the sample collection bottle was replaced prior to 

each storm.

All samples were shipped on ice overnight to 

TestAmerica Laboratories in Denver, Colorado, where 

they were analyzed for concentrations of OG and TPH. 

All samples were received by the laboratory in satisfactory 

condition. Concentrations of OG and TPH were determined 

using USEPA methods 1664A SGT and 1664A HEM (OG) 

(USEPA, 1999b).

The reliability of the chemical data was ensured by the 

preparation and analysis of quality-control samples. These 

quality-control samples include a field blank and five replicate 

samples. A field blank is used to test for positive bias that 

can result from contamination at any stage of the samplecollection, -processing, or -analysis process. One field blank 

was collected with the automatic sampler in preparation 

for storm sampling. This sample was collected by pumping 

organic-free blank water through the automatic sampler tubing 

and into the collection bottle and processing it in a manner 

consistent with the collection of environmental samples of 

stormwater. The laboratory did not detect TPH in this sample; 

however, they did estimate a concentration for OG (3.8 mg/L) 

less than the laboratory reporting limit (5 mg/L) but greater 
Methods 15

Figure 9. A vacuum truck emptying the entire contents of a single catch basin on a tarp prior to sample processing.

than the method detection limit (1.4 mg/L). Concentrations 

of OG in flow-weighted composite samples of highway 

runoff ranged from 7.2 to 34 mg/L. On the basis of these 

values, the results for the field blank indicate that the cleaning 

procedure for the sampling equipment was adequate to prevent 

contamination due to prior use at greater than the reporting 

limit for each constituent. Analysis of laboratory method 

blanks indicates that all samples for TPH were affected 

by low-level laboratory contamination. A method blank 

is a sample used by the laboratory to monitor the level of 

contamination introduced during the sample preparation steps. 

Concentrations of TPH measured in method blanks were less 

than the laboratory reporting limit (5 mg/L) and greater than 

the detection limit (0.8 mg/L) for all samples.

Replicate samples are samples that are thought to be 

identical in composition to the environmental samples. 

Replicate samples provide a measure of bias and variability 

for the methods of sample collection, sample processing, 

and laboratory analysis, and for effects such as analyte 

degradation that can occur prior to laboratory analysis. A 

total of five replicate samples were collected. Two sequential 

replicate samples of sump water and three replicate-split 

samples of stormwater were collected to measure the 

variability of sample concentrations resulting from collection 

and processing of the water samples. Analysis of replicate 

highway runoff and sump water-column samples indicate that 

measurements for OG and TPH can be highly variable. The 

relative percent difference (RPD) between concentrations 

of OG in the primary samples and replicate samples ranged 

from 9 to 123 percent; the RPD between concentrations of 

TPH in primary samples and replicate samples ranged from 

4 to 110 percent. The largest RPDs were observed for the 

two replicate samples collected from the catch basin sumps. 

The large difference between the primary sample and the 

replicate sample representing the surface film of the water 

column in catch basin 739 is likely the result of the bulk of 
16 Effectiveness of Catch Basins Equipped with Hoods in Retaining Gross Solids and Hydrocarbons in Runoff, Boston, Massachusetts, 2008–09 Table 5. Total mass of highway solids collected from various points in the highway drainage system and the effectiveness for the six deep-sump off-line hooded catch basins in retaining gross solids along Southeast Expressway, in Boston, Massachusetts. [--, no data available]Sample description Mass of solids, in grams Site designation and type of catch-basin hood 130 (Snout) 131 (Cast iron) 136 (Eliminator) 137 (Eliminator) 739 (Eliminator) 742 (Cast iron) Catch basin outlet (total) 498.1 855.2 2,071 604.73 2,413 1,094 Catch basin outlet high-density plastics 61.07 19.11 128.0 129.3 223.8 8.39 Catch basin outlet anthropogenic low-density solids 78.41 177.6 224.1 46.12 283.0 232.2 Catch basin floatables 31.62 -- 184.8 22.36 262.7 132.3 Catch basin sump (total) 392.3 939.2 1,811 203.2 663.8 833.9 Catch basin sump high-density plastics 310.3 419.9 1,090 112.44 595.2 375.8 Catch basin sump anthropogenic low-density solids 82.00 519.2 720.5 90.74 68.69 458.0 Effectiveness criteria Effectiveness for each deep-sump hooded catch basin, in percent Gross solids (excluding mineral and metallic materials) 46 52 49 27 28 47 Low-density gross solids 21 38 32 19 13 35 Floatable solids (measured at conclusion of study) 6 -- 6 4 10 8 Anthropogenic low-density solids 59 75 80 71 54 72
Methods 17

Figure 10. A vertical water-column sample being collected with a Teflon dip-stick sampler from 

catch basin 739 on the Southeast Expressway in Boston, Massachusetts, 2009.
18 Effectiveness of Catch Basins Equipped with Hoods in Retaining Gross Solids and Hydrocarbons in Runoff, Boston, Massachusetts, 2008–09

the floating compounds being collected in the primary sample 

with less remaining for collection in the replicate sample. The 

difference between primary and replicate samples collected by 

the dip-stick sampler could have resulted from the agitation 

of bottom sediments during sample collection. The average 

RPDs for concentrations of OG and TPH in three flowweighted composite samples were more precise at 17 and 

10 percent, respectively.

Effectiveness of Catch-Basin Hoods 

Samples of gross solids collected at the outlet of the six 

catch basins were summed and compared to the materials 

collected from the respective catch-basin sumps to compute 

the effectiveness of each catch basin to retain various solids 

during the study period. In this section, rainfall and runoff 

characteristics for each sampling period are compared to the 

mass of solids collected at the outlets of selected catch basins. 

Concentrations of OG and TPH in sump water and in flowweighted composite samples of highway runoff are compared 

among five catch basins and to recent data from a prior study 

(Smith, 2002).

Retaining Gross Solids

A mass balance approach was used to assess the 

effectiveness of each catch basin equipped with a hood in 

retaining gross solids. At the conclusion of the monitoring 

period, the effectiveness of each deep-sump hooded catch 

basin (table 5) was calculated by dividing the sum of the 

catch-basin floatables and total gross solids from the catchbasin sump by the sum of the total gross solids (catch-basin 

floatables, catch-basin sump (total), and catch-basin outlet 

(total) from table 5). 

The effectiveness of the catch basins equipped with the 

cast-iron, Eliminator, and Snout hoods in retaining gross solids 

ranged from 27 to 52 percent. The average effectiveness for 

the three catch basins fitted with the Eliminator hoods was 

about 35 percent, the average effectiveness for the two catch 

basins fitted with cast-iron hoods was about 49 percent, and 

the effectiveness for the catch basin fitted with the Snout hood 

was 46 percent. 

High-density plastics such as lenses for automobile tail 

and parking lights, for example, were identified in both the 

sump and catch-basin outlet samples. From 45 to 90 percent 

of the gross solids in the catch-basin sumps were composed 

of materials made of high-density plastics, and about 1 to 

21 percent of the total gross solids in samples collected at the 

outlet of each catch basin were composed of like materials 

(table 5). The effect that the catch-basin hoods have on 

these materials is likely marginal because these materials 

readily sink in water. When high-density plastic materials are 

eliminated from the sump and outlet values, the effectiveness 

for the deep-sump hooded catch basins is substantially 

lower (table 5, effectiveness for low-density gross solids). 

These results more likely reflect the ability of the device 

to retain true floatable debris because the remaining sump 

materials (largely cigarette butts) are buoyant when dry. The 

effectiveness of the catch basins in retaining gross low-density 

solids ranged from 13 to 38 percent; the average effectiveness 

of retaining gross floatable solids for the three catch basins 

fitted with the Eliminator hoods was about 21 percent. The 

effectiveness for each catch basin, based solely on the material 

that remained floating in the catch basin at the end of the 

monitoring period, was less than 11 percent for all types of 

hoods (table 5, effectiveness for floatable solids). However, 

these values underestimate the catch basin effectiveness 

because it is likely that the hoods initially retain much of 

the saturated solids that settle within the catch-basin sumps 

during non-storm conditions. In the absence of the hoods, such 

materials potentially could flush from the catch basins during 

storms before they reach a saturated condition. Thus, the 

actual effectiveness for the catch basins equipped with hoods 

for retaining gross floatable solids is likely in the range of 13 

to 38 percent for highway settings.

The distribution of identifiable materials collected from 

the outlets of the six catch basins was similar (fig. 11). From 

71 to 83 percent of all solids collected at the outlets of the six 

catch basins was natural vegetation matter. These distributions 

are similar to results for highway locations listed in other 

studies (Kim and others, 2006; ASCG, Incorporated, 2005; 

Kim and others, 2004). If the calculation for the effectiveness 

of the catch basins equipped with hoods is restricted to 

low-density anthropogenic materials (that is, floatable litter 

and automobile refuse) that are not readily biodegradable, 

the effectiveness for most hooded catch basins increases 

(table 5, anthropogenic low-density solids). Although such 

omissions seemingly improve the perceived effectiveness of 

the catch basins, natural organic matter will decompose and 

release nutrients and other constituents into the receiving 

water body, and therefore, natural organic matter should be 

included as objects of concern. Previous research indicates 

that the effectiveness for deep-sump hooded catch basins may 

be improved with more frequent catch-basin maintenance 

(USEPA,1999a); however, this may be impractical given the 

small amount of gross solids measured weekly (< 100 grams) 

in the catch basin outlets during this study. 

The recovery of seed materials from the outlets of the 

catch basins after storms was largely limited to catch basins 

equipped with cast-iron hoods (table 6). In the case of the 

catch basin at site 131, the sump water tended to leak during 

dry periods. As a result, the seed material potentially could 

circumvent the hood as the water level in the sump increases 

and traps the materials between the hood and the catch-basin 

outlet. Seed materials also potentially could circumvent the 

cast-iron hoods through gaps between the edge of the hood 

and the walls of the catch basin at both sites equipped with 

these hoods. 
Effectiveness of Catch-Basin Hoods 19

Highway station 130, "Snout"

Cigarette butts

8%

Plastic materials

20%

Highway station 131, cast-iron hood

Cigarette butts

8%

Plastic materials

15%

Highway station 136, "Eliminator"

Highway station 137, "Eliminator" Highway station 739, "Eliminator" Highway station 742, cast-iron hood

Grass, leaves,

and woody

materials

72%

Grass, leaves,

and woody

materials

77%

Grass, leaves,

and woody

materials

71%

Grass, leaves,

and woody

materials

79%

Grass, leaves,

and woody

materials

83%

Grass, leaves,

and woody

materials

78%

Cigarette butts

5%

Plastic materials

12%

Cigarette butts

3%

Plastic materials

26%

Cigarette butts

5%

Plastic materials

16%

Cigarette butts

9%

Plastic materials

13%

Figure 11. Pie chart showing the distribution of highway solids collected from the outfalls of six deep-sump off-line hooded 

catch basins along the Southeast Expressway in Boston, Massachusetts, May through November 2008.

Stormwater mobilizes litter and other highway solids 

along the roadway where it is transported to the highway 

drainage systems. As a result, the magnitude of the physical 

attributes for storms can affect the loading rates for litter and 

other gross solid loads (Kim and others, 2006; Kayhanian 

and others, 2002). In this study, the effectiveness of catch 

basins equipped with hoods decreased with an increase in 

rain intensity and peak flow. The Pearson product moment 

correlation coefficient was used to evaluate the degree of 

linear relationship between two variables (Helsel and Hirsch, 

2002). The correlation coefficient ranges from -1 to +1. 

A negative coefficient indicates that one variable tends to 

increase as the other decreases, and a positive coefficient 

indicates that the two variables tend to increase together. The 

size of the coefficient from 0 to 1 and 0 to -1 indicates the 

extent of the relation. The Pearson correlation coefficients 

for gross solids (normalized by drainage area) collected from 

the outlet pipes for catch basins 136 and 739 to maximum 

1-hour rainfall intensity and peak flow are 0.66 and 0.79, 

respectively. The Pearson correlation coefficients for total 

rainfall, total duration, and total volume of flow for each 

sampling period to gross solids are 0.31, -0.01, and 0.40, 

respectively. The division point that marks where there is or is 

not a linear relation between the two variables is determined 

from the size of the sample population (Johnson, 1984). For 

this study, the coefficients are computed from 30 sets of paired 

values (table 2; rain statistics are assumed to represent all 

sites for respective sampling periods), and the division point 

is 0.361 (Johnson, 1984). Thus, there is sufficient evidence 

to conclude that there are linear relations between 1-hour 

rainfall intensity, peak flow, and total volume of flow for each 

sampling period to gross solids because the respective Pearson 

correlation coefficients are greater than the division point. 

The loss of seed materials from the sump of the catch basins 

did not coincide with the high rainfall intensity and peak flow 

events. In general, the seed materials were larger and probably 

more buoyant than the bulk of the floatable solids measured 

in this study and did not respond to high intensity rainfall or 

peak rates of flow as did the small pieces of liter and natural 

organic materials. As a result, the effectiveness of the hoods in 

retaining large floatable items, which were limited in size by 

the catch basin grates in this study, may be greater.

Although there are many areas along highways where 

the amount of visible litter affects the surrounding aesthetics, 

catch-basins equipped with hoods may provide only limited 

benefit on Massachusetts highways because the small openings 

in the catch-basin grates restrict the potential capture of many 

of these larger items (beverage cups, cans, and bottles). The 

data presented in this report are not necessarily transferable to 

catch basins with different grate designs or catch basins that 

contain curb inlets which may allow larger material to pass to 

the catch basin sump. 
20 Effectiveness of Catch Basins Equipped with Hoods in Retaining Gross Solids and Hydrocarbons in Runoff, Boston, Massachusetts, 2008–09 Table 6. Recovery of seed materials from the debris-collection structures at the outlets of the six deep-sump off-line hooded catch basins and storm statistics for each period between sample collections along Southeast Expressway, in Boston, Massachusetts, 2008. [mm/dd, month/day] Sample collection date (mm/dd) Rainfall Statistics Number and type of seed material collected from catch basin outlet Site designation and hood type Total rainfall (inches) Maximum rainfall intensity (inches per hour) Number of storms between sample collections 130 (Snout) 131 (Cast iron) 136 (Eliminator) 137 (Eliminator) 739 (Eliminator) 742 (Cast iron) Tube Bag Tube Bag Tube Bag Tube Bag Tube Bag Tube Bag 05/14 0.24 0.07 2 0 0 0 0 0 0 0 0 0 0 0 0 05/17 0.78 0.16 1 0 0 0 0 0 0 0 0 0 0 0 0 05/28 0.20 0.12 1 0 0 2 1 0 0 0 2 0 0 0 0 06/05 0.56 0.14 3 0 0 0 0 0 0 0 0 0 0 0 0 06/17 1.03 0.25 4 0 0 0 1 0 0 0 0 0 0 0 0 06/24 0.12 0.08 1 0 0 7 3 0 0 0 0 0 0 0 0 07/02 0.89 0.66 3 0 0 0 2 0 0 0 0 0 2 0 0 07/11 0.72 0.45 3 0 0 0 0 0 0 0 0 0 0 5 0 07/21 0.87 0.39 4 0 1 0 0 0 0 0 0 0 0 3 0 07/30 4.38 1.33 6 0 0 0 0 0 0 0 0 0 0 2 0 08/04 1.06 0.73 4 0 0 0 0 0 0 0 0 0 0 0 0 08/13 1.63 0.37 8 0 0 0 0 0 0 0 0 0 0 0 0 08/28 0.46 0.13 3 0 0 0 0 0 0 0 0 0 0 0 0 09/09 2.10 0.54 2 0 0 0 0 0 0 0 0 0 0 0 0 09/24 0.83 0.30 3 0 0 0 0 0 0 0 0 0 0 0 0 09/30 3.85 0.48 3 0 0 0 0 0 0 0 0 0 0 0 0 11/03 1.44 0.29 6 0 0 0 0 0 0 0 0 0 0 0 0 Seed materials recovered during storms, in percent

0 10 90 70 0 0 0 20 0 20 100 0
Effectiveness of Catch-Basin Hoods 21

Retaining Oil and Grease and Total 

Petroleum Hydrocarbons 

Water samples were collected from the catch-basin sumps 

and a catch-basin outlet during storms to assess the general 

effectiveness of the hoods in retaining OG and TPH within 

the catch basins. OG materials analyzed for include relatively 

non-volatile hydrocarbons, vegetable oils, animal fats, waxes, 

soaps, greases, and related materials (USEPA, 1999b). 

TPH materials are more restrictive, consisting of numerous 

relatively non-volatile hydrocarbon compounds that originate 

from crude oil. Hydrocarbons in petroleum fuels ranging from 

gasoline through number-2 fuel oil, which volatilize below 

85oC, may be only partially represented in such analyses 

because these hydrocarbons can be lost in the analytical 

process (USEPA, 1999b). Although methods for both types 

of hydrocarbons provide measurements for a group of rather 

non-specific compounds, test results from sample to sample 

may not necessarily represent the same source.

Water samples collected from the water surface of the 

catch-basin sumps represent the floating film of OG and TPH 

and, possibly, the maximum concentrations in the water in 

each catch basin. These 1-liter samples represent a water depth 

of less than 0.1 in., given the surface area of the catch basins. 

Concentrations of OG measured in samples of water collected 

from the upper water surfaces of the catch-basin sumps ranged 

from 6.5 to 46 mg/L (table 7). Concentrations of TPH in 

the same samples ranged from 3.2 to 26 mg/L (table 7). The 

lowest concentrations of both constituents were measured 

in samples collected in the catch basin at site 130 where the 

Snout hood was installed. The highest concentrations of OG 

were measured in samples collected in the catch basin at site 

739 where the Eliminator hood was installed. Concentrations 

of OG also were high in samples collected in the catch basin 

at site 742 containing a cast-iron hood. Samples from this site 

also had the highest concentrations of TPH. The variability 

among these measurements is more likely a function of a nonuniform source of the constituents from site to site rather than 

an indication of the actual performance for each hood. The 

cast-iron hood installed in the catch basin at site 742 loosely 

fit over the outlet of the sump; as a result, this hood could not 

physically prevent floatable compounds from escaping the 

sump. This particular catch basin was located in an emergency 

pull-off area; thus the high concentrations of both constituents 

measured in samples collected from this catch basin likely 

are explained by the greater probability that runoff might be 

affected by emissions from disabled automobiles. 

The distributions of concentrations of OG and TPH 

measured in flow-weighted composite samples of highway 

runoff collected at the outlet of the catch basin at site 739 

(fitted with an Eliminator hood; table 8) are shown in figure 12 

alongside concentrations of the respective constituents 

collected previously from deep-sump catch basins containing 

cast-iron hoods in the same study area (Smith, 2002). Unlike 

Table 7. Concentrations of oil and grease, and total petroleum hydrocarbons collected from the water 

surface in sumps of five deep-sump off-line hooded catch basins along the Southeast Expressway, in Boston, 

Massachusetts, 2008–09.

[mm/dd/yyyy, month/day/year; mg/L, milligrams per liter; j, analyte was detected in method blank at a concentration less than 

the reporting limit (5 mg/L) and greater than the detection limit (0.8 mg/L); values in parentheses are concentrations for replicate 

samples; e, result is less than the reporting limit]

Site designation Sample date 

(mm/dd/yyyy)

Oil and grease 

(mg/L)

Total petroleum hydrocarbons 

(mg/L)

130 11/3/2009 6.5 5.1 j

4/29/2009 6.5 3.2 e, j

136 11/3/2009 19 12 j

4/29/2009 19 6.7 j

137 11/3/2009 7.4 3.5 j, e

4/29/2009 34 12

739 9/30/2008 46 (11) 26 j (7.6 j)

10/29/2009 7.8 5.7 j

4/29/2009 15 7.7 j

742 10/29/2009 23 15 j

4/29/2009 34 13 j
22 Effectiveness of Catch Basins Equipped with Hoods in Retaining Gross Solids and Hydrocarbons in Runoff, Boston, Massachusetts, 2008–09

Table 8. Concentrations of oil and grease, and total petroleum hydrocarbons, in flow-weighted samples of highway runoff collected 

from the outlet of catch basin 739 and in a vertical-profile sample collected in the sump of catch basin 739 along the Southeast

Expressway, in Boston, Massachusetts, 2008–09.

[mm/dd/yyyy, month/day/year; mg/L, milligrams per liter; j, analyte was detected in method blank at a concentration less than the reporting limit (5 mg/L) and 

greater than the detection limit (0.8 mg/L); values in parentheses are concentrations for replicate samples; e, result is less than the reporting limit]

Sample date 

(mm/dd/yyyy)

Storm runoff volume 

(cubic feet)

Oil and grease 

(mg/L)

Total petroleum hydrocarbons 

(mg/L)

12/10/2008 1,610 7.2 (9.2) 4.4 e (4.6 e)

3/9/2009 617 34 (31) 10 j (9.5 j)

4/3/2009 235 15 (18) 7.8 j (9.6 j)

4/6/2009 590 13 4.1 e, j

4/11/2009 76.6 7.6 j 3.3 e, j

Total static sump volume (cubic feet)

4/29/2009 50 11 (19) 4.2 e, j (6.5 e, j)

25th percentile

75th percentile

Median

 Maximum

 Minimum

Mean

(26) Number of observations

EXPLANATION

2002

0.5

5

50 (5) (12) (5)

CONCENTRATION, MILLIGRAMS PER LITER

OIL AND GREASE

(10)

2009 2002 2009

TOTAL PETROLEUM

HYDROCARBONS

Figure 12. Box plot of the distribution of concentrations of oil and grease, and total petroleum hydrocarbons, measured 

in composite samples, collected in a prior U.S. Geological Survey study (Smith 2002), of highway runoff discharged from 

deep-sump off-line catch basins containing cast-iron hoods and those measured in composite samples of highway runoff 

discharged from a deep-sump off-line catch basin equipped with an Eliminator hood collected in this study (2009) along 

the same section of road on the Southeast Expressway in Boston, Massachusetts.
Summary 23

the loose fit of the cast-iron hood, the Eliminator hood fit 

tightly in the outlet pipe of the catch basin, and as a result, this 

device could retain floating oil and grease in the catch-basin 

sump under static conditions. However, the concentrations 

of OG and TPH in samples of highway runoff were not 

substantially different from those concentrations measured 

in samples of highway runoff collected from catch basins 

containing cast-iron hoods, which have no ability to retain 

floatable oils and grease. Furthermore, the similarity between 

the concentrations of the respective constituents in the vertical 

profile sample collected from the sump at the conclusion of 

storm sampling and the concentrations measured in samples 

of highway runoff indicates that the load for each constituent 

discharged from the catch basin dwarfs what was remaining in 

the sump of the catch basin. For example, the load of OG and 

TPH measured at the outlet of catch basin 739 for just the five 

storms sampled in this study was more than 80 times greater 

than the load remaining in the sump of the catch basin in 

April 2009, about 5 months after the catch basin was cleaned. 

These data indicate that OG and TPH become emulsified in 

the sump of each catch basin during storms and circumvent 

the hoods. However, during static conditions, the Eliminator 

hood, and presumably the Snout hood as well, potentially 

could retain more than 6 ft3 of floatable oils (assuming a catch 

basin 4 ft in diameter and a hood depth of about 0.5 ft below 

the catch-basin outlet) that result from breached fuel tanks or 

other lubricant reservoirs as the sump water is displaced by a 

floating layer of product less than or equivalent to the depth 

of the hood below the catch-basin outlet. If the depth of the 

floating product exceeds the bottom of the hood, the product 

will begin to discharge from the catch basin.

Summary

The USGS, in cooperation with the Federal Highway 

Administration and the Massachusetts Department of 

Transportation began a study in 2008 to determine the 

effectiveness of catch-basin hoods in reducing the mass of 

gross solids and concentrations of OG and TPH along the 

Southeast Expressway, Boston, Massachusetts. Six deep-sump 

off-line catch basins were selected for monitoring and for 

the collection of gross solids (potentially floatable materials 

greater than 0.25 in. in diameter). These catch basins are 

located near, if not adjacent to, each other on two north-bound 

sections of highway about a mile apart. Existing cast-iron 

hoods were left installed in two catch basins. Molded plastic 

hoods, known as an Eliminator, were installed in three catch 

basins, and a single fiberglass anti-siphoning hood, known as a 

Snout, was installed in one catch basin. 

A debris collection structure was installed at the outlet of 

each catch basin after the sump of the catch basin was cleaned. 

Floatable seed materials were subsequently added to each 

catch basin once the water in the sump recovered to a normal 

level and submersed the bottom of the hoods. Instantaneous 

flows were calculated from water-level measurements made 

behind weirs installed in the outlets of three catch basins. 

Instantaneous measurements of rainfall also were recorded 

near one catch basin. Samples of sump water for five catch 

basins were collected in November 2008 and again in April 

2009 and analyzed for concentrations of OG and TPH. Flowweighted composite samples of highway runoff also were 

collected from the outlet of one catch basin during five storms 

from December 2008 to April 2009. These samples also were 

analyzed for concentrations of OG and TPH. Samples of gross 

solids were routinely collected from the collection structures 

at the outlet pipe of the six catch basins and dried to a constant 

weight. Seed materials were removed from the mass of solids 

and tabulated. Identifiable materials from the samples of gross 

solids were placed in three general categories (cigarette butts, 

plastics, and natural vegetation matter), and the mass for each 

category was determined. After about 6 months, all floatable 

debris were removed with a net from each catch basin, and the 

remaining sump contents were removed from one catch basin 

at a time with a vacuum truck. The entire contents for each 

catch basin was wet sieved, and the mass of gross solids was 

determined after the samples were dried to a constant weight. 

The total mass of high-density plastics in samples collected 

from the debris collection structures at the outlet pipes and the 

sumps was determined for each catch basin. 

A mass-balance approach was used to assess the 

effectiveness of each catch basin equipped with a hood 

in retaining gross solids. The overall effectiveness of the 

deep-sump catch basins equipped with cast-iron, Eliminator, 

and Snout hoods in retaining gross solids ranged from 27 

to 52 percent. The average effectiveness for the three catch 

basins fitted with the Eliminator hoods was 35 percent, the 

average effectiveness for the two catch basins fitted with castiron hoods was about 49 percent, and the effectiveness for the 

catch basin fitted with the Snout hood was 46 percent. From 

45 to 90 percent of the gross solids collected from the catchbasin sumps were composed of materials made of high-density 

plastics that did not float in water; therefore, the effect that the 

catch-basin hoods had on these materials was likely marginal. 

The effectiveness for the deep-sump hooded catch basins 

estimated on the basis of low-density solids are substantially 

less (13 to 38 percent). The effectiveness for each catch basin, 

based solely on the material that remained floating at the end 

of the monitoring period, was less than 11 percent; however, 

these values likely underestimate the effectiveness of the 

catch basin since much of the low-density material collected 

from the sumps may have been retained as floatable materials 

before they were saturated and settled in the catch-basin 

sumps during non-storm conditions. 

The effectiveness of the catch basins equipped with 

hoods did not differ greatly among the three types of hoods 

tested in this study. The recovery of seed materials in the 

outlets of the catch basins after storms was largely limited 

to catch basins equipped with cast-iron hoods where seed 

material likely circumvented the hoods as a result of gaps 

between the edge of the hood and the walls of the catch basin. 
24 Effectiveness of Catch Basins Equipped with Hoods in Retaining Gross Solids and Hydrocarbons in Runoff, Boston, Massachusetts, 2008–09

The distribution of identifiable materials collected from the 

outlets of the six catch basins was similar; 71 to 83 percent of 

all solids consisted of natural vegetation matter, 3 to 9 percent 

consisted of cigarette butts, and 12 to 26 percent consisted of 

various plastic materials. Correlations between the mass of 

gross highway solids collected from the outlet of the catch 

basins normalized by drainage area and storm characteristics 

indicate that the effectiveness of catch basins for retaining 

gross solids decreased with an increase in rain intensity, peak 

flow, and total volume of flow.

Concentrations of OG and TPH collected from the water 

surface of the catch-basins varied from catch basin to catch 

basin irrespective of hood type. These results indicate that 

concentrations of OG and TPH were more likely from nonuniform sources than evidence of differences in effectiveness 

of each structural best management practice. Comparisons 

revealed that concentrations of OG and TPH in flow-weighted 

composite samples of highway runoff collected at the outlet 

of a catch basin equipped with an Eliminator hood were not 

substantially different from those concentrations in flowweighted composite samples of highway runoff for the 

respective constituents collected from catch basins containing 

cast-iron hoods in the same study area for a previous study. 

The similarity between these flow-weighted concentrations 

from this study and the concentrations of the respective 

constituents in a vertical profile sample collected from 

the catch-basin sump indicates that OG and TPH become 

emulsified in the sump of each catch basin during storms and 

circumvent the hoods. However, during static conditions, the 

Eliminator hood, and presumably the Snout hood as well, 

potentially could provide spill control for floatable fuel and 

lubrication fluids.

References Cited

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Flood Control Authority and the City of Albuquerque/

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uquerquems4floatableandgrosspollutantstudy.pdf.

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Kayhanian, Masoud, Kummerfeldt, Steve, Kim, Lee-Hyung, 

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Washington, D.C.: U.S. Environmental Protection Agency 

Report EPA–832–F99–008, September 1999, 7 p.

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Prepared by the Pembroke Publishing Service Center.

For more information concerning this report, contact:

Director

U.S. Geological Survey

Massachusetts-Rhode Island Water Science Center

10 Bearfoot Road

Northborough, MA 01532

dc_ma@usgs.gov

or visit our Web site at:

http://ma.water.usgs.gov
Smith—Effectiveness of Catch Basins Equipped with Hoods in Retaining Gross Solids and Hydrocarbons in Runoff, Boston, MA, 2008–09—Scientific Investigations Report 2010–5182

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