Ground-Water Quality Data from the AbbotsfordSumas Aquifer of Southwestern British Columbia 

and Northwestern Washington State, February 1997

By Stephen E. Cox* and Hugh Liebscher**

* U.S. Geological Survey 

** Environment Canada

U.S. GEOLOGICAL SURVEY 

Open-File Report 99-244

Prepared jointly with 

ENVIRONMENT CANADA

Tacoma, Washington 

1999
U.S. DEPARTMENT OF THE INTERIOR

BRUCE BABBITT, Secretary

U.S. GEOLOGICAL SURVEY

Charles G. Groat, Director

Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the 

U.S. Geological Survey.

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

District Chief U.S. Geological Survey

U.S. Geological Survey Branch of Information Services

1201 Pacific Avenue, Suite 600 Box 25286

Tacoma, Washington 98402 Denver, Colorado 80225
CONTENTS

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

Introduction ..................................................................................................................................................................^

Purpose and scope .......................................................................................................................................................2

Description of the aquifer............................................................................................................................................2

Sample collection and analysis..............................................................................................................................................4

Site selection................................................................................................................................................................4

Water-quality constituents ...........................................................................................................................................4

Sample collection and processing procedures.............................................................................................................4

Laboratory procedures................................................................................................................................................. 15

Quality assurance...................................................................................................................................................................16

Quality-assurance/quality-control samples.................................................................................................................. 16

Data quality assessment...............................................................................................................................................16

Water-quality results..............................................................................................................................................................2

Nutrients, common ions, and trace elements...............................................................................................................20

Pesticides and volatile organic compounds.................................................................................................................21

Chlorofluorocarbons....................................................................................................................................................21

Summary................................................................................................................................................................................22

References cited.....................................................................................................................................................................23

Appendix ...........................................................................................................................................................................^

FIGURE

1. Map showing location of wells sampled in the Abbotsford-Sumas aquifer, February 1997......................................3

TABLES

1. Water-level and well construction information of sampled wells...........................................................................5

2. Field measurements, common ions, nutrients, and trace elements measured in filtered groundwater samples collected from wells in the Abbotsford-Sumas aquifer, February 1997..........................................6

3. Volatile organic compounds analyzed in ground water from the Abbotsford-Sumas aquifer, 

February 1997, and minimum reporting levels, drinking water standards, and freshwater 

criteria for protection of aquatic life .......................................................................................................................7

4. Pesticide compounds analyzed in ground water from the Abbotsford-Sumas aquifer, 

February 1997, and minimum reporting levels, drinking water standards, and freshwater 

criteria for protection of aquatic life ....................................................................................................................... 11

5. Volatile organic compounds and pesticides detected in samples of shallow ground water from

the transboundary region of the Abbotsford-Sumas aquifer, February 1997.......................................................... 17

6. Field measurements and concentrations of inorganic constituents in transboundary ground

water from the Abbotsford-Sumas aquifer.............................................................................................................. 18

7. Concentration of chlorofluorocarbons in ground-water samples and calculated equalibrium

vapor phase concentration.......................................................................................................................................22

III
CONVERSION FACTORS AND VERTICAL DATUM

Multiply

centimeter (cm)

meter (m)

kilometer (km)

square kilometer (km2)

liter (L)

By

0.3937

3.281

0.6214

0.3861

0.2642

To obtain

inch

foot

mile

square mile

gallon

Temperature: To convert temperature given in this report in degrees Celsius (°C) to degrees Fahrenheit (°F), use the 

following equation: °F = 9/5 °C + 32.

Sea Level: In this report "sea level" refers to the National Geodetic Vertical Datum of 1929 (NGVD of 1929)~a

geodetic datum derived from a general adjustment of the first-order level nets of both the United States and Canada, formerly

called Sea Level Datum of 1929.

Elevation: In this report, "elevation" is measured in meters above sea level.

IV
Ground-Water Quality Data from the AbbotsfordSumas Aquifer of Southwestern British Columbia and 

Northwestern Washington State, February 1997

By Stephen E. Cox and Hugh Liebscher

ABSTRACT

Ground-water quality and hydrogeologic 

data were collected from nine wells in the 

Abbotsford-Sumas aquifer near the international 

boundary separating Canada and the United 

States. The samples were collected to provide 

detailed information on the concentrations of 

chemical constituents in ground water moving 

from Canada to the United States. Samples 

were analyzed for a selection of common ions, 

nutrients, trace elements, pesticides, and volatile 

organic compounds including three chlorofluorocarbons used to estimate residence times of 

ground water. The concentrations of nitrate 

were greater than 10 milligrams per liter in 

seven of nine wells exceeding criteria for both 

Canadian and United States drinking water 

guidelines and standards, respectively. The 

concentrations of common ions, trace elements, 

and other nutrients were generally small. 

Twenty-three pesticides and volatile organic 

compounds were detected in the ground water. 

The concentrations of these organic compounds 

ranged from 0.01 to 23 micrograms per liter, 

which were below drinking water guidelines or 

standards. Three chlorofluorocarbons were 

detected in these ground-water samples. 

Concentrations of chlorofluorocarbons were 

generally much greater than would be useful 

to provide reliable estimates of ground-water 

residence time.

RESUME

Des donnees concernant la qualite des eaux 

souterraines et des donnees hydrogeologiques ont 

ete recueillies a partir d'echantillons preleves dans 

neufs puits plongeant dans la nappe aquifere 

d'Abbotsford-Sumas, pres de la frontiere canadoamericaine. Les echantillons ont ete preleves pour 

determiner avec precision la concentration des 

produits chimiques contenus dans les eaux souterraines qui passent du Canada aux Etats-Unis. On a 

mesure dans ces echantillons un certain nombre 

d'ions communs, de nutriants, d'oligo-elements, 

de pesticides et de composes organiques volatiles, 

dont trois chlorofluorocarbones utilises pour 

estimer le temps de sejour de 1'eau souterraine.

La concentration de nitrates s'est averee 

superieure a 10 milligrammes par litre dans sept 

des neuf puits, ce qui depasse les directives canadiennes et les normes americaines en matiere d'eau 

potable. La concentration des ions communs, des 

oligo-elements et des autres nutriants etait en 

generate faible. Vingt-trois pesticides et composes 

organiques volatiles ont d'autre part ete detectes 

dans les echantillons. La concentration de 

ces composes organiques variait entre 0,01 et 

23 microgrammes par litre, au-dessous de la limite 

imposee par les directives et les normes en matiere 

d'eau potable. Trois chlorofluorocarbones ont ete 

detectes mais leur concentration etait en general 

trop grande pour que Ton puisse les utiliser pour 

estimer de facon fiable le temps de sejour de 1'eau 

souterraine.
INTRODUCTION

The Abbotsford-Sumas aquifer is bisected by the 

international boundary between the Province of British 

Columbia, Canada, and the State of Washington, 

United States of America (fig. 1). In this area, the 

Abbotsford-Sumas aquifer is the most extensively used 

aquifer on both sides of the international boundary. 

It supplies water for domestic, municipal, agricultural, 

and industrial purposes for residents of both countries. 

Residents of Abbotsford and Sumas, as well as most 

rural residents in the area, obtain their water from this 

aquifer. During peak water demands, the aquifer 

currently supplies water to over 115,000 people. In 

addition, the aquifer provides the majority of baseflow 

to several fish rearing tributaries of the Nooksack, 

Sumas, and Fraser Rivers.

Land use over most of the aquifer is largely 

agricultural. Poultry and raspberry production are the 

predominant agricultural activities over the Canadian 

side of the aquifer while dairy and raspberry production are the major activities over the United States side 

of the aquifer. Other agricultural activities include 

corn, potato, and swine production. Urban development and light industry are centered around the Cities 

of Abbotsford, Lynden, and Sumas. Rural residential 

housing is increasing throughout the area.

The quality of ground water in the AbbotsfordSumas aquifer is a concern to residents and government 

agencies of both Canada and the United States. Previous investigations have identified nitrate contamination 

and the presence of selected pesticides in ground water 

of the Abbotsford-Sumas aquifer at a number of 

locations on both sides of the international boundary 

(Liebscher and others, 1992; Erickson and Norton, 

1990; Cox and Kahle, 1999). Information was lacking 

on the occurrence and concentrations of a broad 

spectrum of other organic compounds and waterquality constituents in ground water flowing across the 

boundary.

Purpose and Scope

The objective of this investigation was to determine if selected organic compounds and trace elements 

were present in a single set of ground-water samples 

collected from the transboundary area of the Abbotsford-Sumas aquifer. This report presents data from 10 

samples of ground water collected from 9 water-table

wells located near the boundary between Canada and 

the United States from February 3 to February 7,1997. 

The data were collected jointly by the U.S. Geological 

Survey (USGS) and Environment Canada (EC), utilizing sampling and analytical techniques developed by 

the USGS to accurately measure low concentrations of 

organic compounds and trace elements in ground 

water.

Description of the Aquifer

The Abbotsford-Sumas aquifer is a surficial 

aquifer, located from the City of Abbotsford, British 

Columbia, to Lynden, Washington (fig. 1). The 

Abbotsford-Sumas aquifer is part of a larger surficial 

aquifer that extends throughout much of the Nooksack 

and Fraser River Lowland. The aerial extent of the 

Abbotsford-Sumas aquifer is approximately 161 

square kilometers (62 square miles) and is roughly 

bisected by the Canadian-United States boundary. 

Ground water generally flows southerly, moving across 

the international boundary from Canada to the United 

States (Liebscher and others, 1992; Cox and Kahle, 

1999). Recharge to the aquifer is primarily from direct 

precipitation, which occurs predominantly from 

October to May. Mean annual precipitation varies 

from about 100 centimeters (40 inches) near Lynden 

to 165 centimeters (65 inches) near Abbotsford. 

Discharge from the aquifer is by pumping and seepage 

to streams, most notably Fishtrap Creek and the 

Nooksack River (fig. 1).

The Abbotsford-Sumas aquifer is made up 

predominantly of uncompacted sands and gravels of a 

glacial outwash plain that are permeable and allow 

rapid infiltration. Lenses of fine-grain sediments are 

commonly found throughout the aquifer resulting in 

complex ground-water flow paths. The aquifer is 

underlain by an extensive fine-grain glaciomarine 

deposit that is referred to in Canada as the Fort Langley 

clays, (Halstead, 1986) and in the United States as the 

Everson Glacio-Marine Drift (Easterbrook, 1976). The 

aquifer is typically unconfined and ranges from 0 to 

65 meters (0 to 213 feet) thick. The aquifer is thickest 

in the northeastern part of the aquifer where glacial 

terminal moraine deposits are incorporated within the 

outwash deposits thickening the aquifer and resulting 

in semiconfined conditions at some locations. The 

water table is generally from 3 to 25 meters below land 

surface in the transboundary area.
123° 122°

49°15' -

Abbotsford-Sumas 

Aquifer

Whatcom County 

Skagit County

EXPLANATION 

Well sampled for ground-water quality

10 15 20 MILES

Map 

Number

1

2

3

4

5

6

7

8

9

Well I 

Name

91-13

91-15

FTC-1-24

ABB5

94-LEH

BCME-B-20

ABB2

ABB4

94-SR-29

National Water Information 

System Site Identifier

490023122252902

490023122252901

490009122243102

490020122213201

490010122252901

490031122225301

490020122213201

490011122193201

490011122181001

10 15 20 KILOMETERS

Figure 1. Location of wells sampled in the Abbotsford-Sumas aquifer, February, 1997.
SAMPLE COLLECTION AND ANALYSIS

Site Selection

Ground-water samples were collected from nine 

existing monitoring wells screened in the AbbotsfordSumas aquifer and located in Canada within 400 

meters of the international boundary (fig. 1). The 

criteria for selection of wells for sampling included: 

(1) wells located along and close to the international 

boundary; and (2) existing water-table wells completed 

in the Abbotsford-Sumas aquifer. Six wells were 

within 50 meters north of the international boundary. 

The other wells, BCME-B-20, 91-13, and 91-15, were 

located about 400 meters north of the boundary. Wells 

with shallow depth to water were selected, because the 

potential for contamination was thought to be greatest 

near the water table. Well 94-SR-29, which is screened 

about 16 meters below the water table, was also 

selected because ground water from the area near this 

well flows toward water-supply wells used by the City 

of Sumas, Wash. (Associated Earth Sciences Inc., 

1996).

All wells were constructed of PVC plastic pipe, 

5.1 centimeters (2 inches) in diameter. The length of 

the well screen for four of the observation wells was 

1.51 meters (5 feet); four other wells had screens that 

were 1 meter (3.3 feet) in length. The remaining well, 

94-LEH, was screened from a depth of 4.6 to 21.3 

meters (15 to 70 feet). However, prior to sampling, a 

temporary 0.5-meter (1.6 feet) cellulose packer was 

installed from 5.5 to 6 meters below land surface so that 

only the upper 1 meter of the well screen was open to 

the aquifer while water was being pumped from the 

well. Generally, the static water level in wells was near 

the screened interval. Well-construction and waterlevel data collected prior to sampling are listed in 

table 1. Drillers' descriptions of lithology encountered 

while drilling the wells are included in the appendix.

Water-Quality Constituents

The ground-water samples were collected during 

the winter season because seasonal variations in 

ground-water nitrate concentrations in the AbbotsfordSumas aquifer have been observed to be larger during 

the winter (Dasika, 1996). It is likely that other waterquality constituents related to land-use activities would 

also be largest in the winter.

Ground-water samples from all wells were analyzed in the field at the time of sampling to determine 

the concentration of dissolved oxygen, pH, specific 

conductance, and alkalinity of a filtered water sample. 

Samples collected in polyethylene or glass bottles were 

sent to the National Water Quality Laboratory 

(NWQL), in Arvada, Colo., for laboratory analysis of 

common ions, nutrients, dissolved organic carbon, 

trace elements, volatile organic compounds (VOCs), 

and pesticides. A listing of constituents and minimum 

reporting levels (MRLs) is presented in table 2 for field 

parameters, common ions, nutrients, and trace 

elements. An alphabetical listing of the VOCs and 

pesticides that were analyzed, their chemical names, 

common names, Chemical Abstract Services registry 

numbers, MRLs, and drinking water standards or 

guidelines from the U.S. Environmental Protection 

Agency and Health Canada is presented in tables 3 and 

4. Water-quality data from these analyses are stored in 

the USGS National Water Information System 

(NWIS). Site identifiers used to locate information in 

NWIS are shown in figure 1.

Additional samples from seven wells were sent 

to the USGS Chlorofluorocarbon Laboratory in Reston, 

Virg., for determination of the concentrations of three 

chlorofluorocarbon (CFC) compounds: trichlorofluoromethane, CFC-11; dichlorodifluoromethane, 

CFC-12; and l,l,2-trichloro-l,2,2-trifluoroethane, 

CFC-113. In some instances concentrations of these 

compounds have been shown to be useful in determining when ground water was recharged and thereby 

provide an estimate of the ground-water residence 

times (Busenberg and Plummer, 1992).

Sample Collection and Processing 

Procedures

Sample collection procedures followed the 

protocols and guidelines established for the USGS 

National Water Quality Assessment (NAWQA) 

program to minimize sample contamination 

(Koterba and others, 1995). All sampling equipment 

used was dedicated to sampling ground water with low 

concentrations of organic and inorganic constituents. 

Equipment that came in contact with the samples 

during collection procedures, including the submersible pump, fittings, and water lines, were composed of 

either 316 Stainless Steel, Teflon® or copper. Copper 

tubing was used only in the collection of CFC samples 

where refrigeration-grade copper tubing was used
Table 1. Water-level and well construction information of sampled wells 

[NWIS, National Water Information System]

Well name

Land surface altitude,

meters (feet) above

mean sea level

Well depth, meters (feet)

Screened interval, meters

below land surface

Depth to ground water,

February/97, meters (feet)

Distance from water level to

top of screen interval,

meters (feet)

91-15

46.35*

(152.0)

11.41

(37.4)

8.23-

9.73

2.49

(8.17)

5.73

(18.8)

91-13

46.41

(152.2)

20.8

(68.2)

18-

19.5

3.35

(11.0)

14.33

(47.0)

FTC-1-24

43.87

(143.9)

7.32

(24.0)

6.4-

7.32

1.89

(6.19)

5.43

(17.80)

ABB2

49.11

(161.0)

7.62

(25.0)

6.62-

7.62

0.67

(2.21)

5.95

(19.51)

ABB4

64.90

(212.9)

29.26

(96.0)

28.26-

29.20

21.56

(70.71)

6.92

(22.69)

ABB5

46.40

(152.2)

8.84

(29.0)

7.84-

8.84

0.98

(3.23)

7.86

(25.77)

BCM

B-20

49.

(163.

6.

(20)

4.

6.

2.

(7.

0.

(2.

* Metric unit, meters; English unit in feet in parentheses.
Table 2. Field measurements, common ions, nutrients, and trace elements measured in filtered ground-water samples 

collected from wells in the Abbotsford-Sumas aquifer, February 1997

[mg/L, milligrams per liter; )J.g/L, micrograms per liter. The filter size was 0.45 pm (micrometer, or micron). 

Ammonia, nitrate, and nitrite are reported as nitrogen, and orthophosphate is reported as phosphorus]

FIELD MEASUREMENTS

Constituent or 

physical property

Temperature 

Specific Conductance 

Alkalinity

Reporting 

units

Degrees C 

(Is/cm 

mg/L as CaCO3

Constituent or 

physical property

pH 

Dissolved oxygen

Reporting 

units

Standard unit 

mg/L

COMMON IONS AND NUTRIENTS 

Minimum Minimum

Constituent of 

physical property

Calcium 

Magnesium 

Sodium

Potassium 

Chloride 

Sulfate 

Fluoride 

Silica, as SiO2 

Bicarbonate, as 

Ion balance

HCO3

Reporting Constituent or Reporting 

level (mg/L) physical property level (mg/L)

0.02 

0.01 

0.2

0.1 

0.1 

0.1 

0.1 

0.01 

0.01 

(percent)2

Nitrate plus nitrite, as N 

Nitrite, as N 

Ammonia, as N

Ammonia plus 

organic nitrogen 

Orthophosphate, as P 

Phosphorus 

Carbon, organic, total as C 

Residue on evaporation 

Sum of dissolved constituents

0.05 

0.01 

0.015

0.02 

0.01 

0.01 

0.01 

1 

1

Element

Antimony 

Aluminum

Arsenic 

Barium

Beryllium 

Bromide 

Cadmium

Minimum

Reporting 

level ((J-g/L)

1 

1

1 

1

1 

1 

1

TRACE ELEMENTS

Minimum

Reporting 

Element level ((J-g/L) Element

Chromium 1 Molybdenum 

Cobalt 1 Nickel

Copper 1 Selenium 

Iron 3 Silver

Lead 1 Uranium 

Manganese 1 Zinc 

Mercury 0.1

Minimum

Reporting 

level ((J-g/L)

1 

1

1 

1

1 

1

1 Field parameters other than alkalinity, measured in unfiltered sample water.

percent.
Table 3. Volatile organic compounds analyzed in ground water from the Abbotsford-Sumas aquifer, February 1997, and minimu

standards, and freshwater criteria for protection of aquatic life 

[|Lig/L, micrograms per liter; -, data not available]

Volatile organic

compounds

Acrylonitrile

ten -Amyl methyl ether

Benzene

Bromobenzene

Bromochloromethane

Bromodichloromethane

Bromoethane

Bromomethane

2-Butanone

n-Butylbenzene

sec-Butylbenzene

tert-Butylbenzene

Carbon Disulfide

Chlorobenzene

Chloroethane

Chloroethene

Chloromethane

2-Chloro- 1-methylbenzene

4-Chloro-l -methyl benzene

3-Chloro- 1 -propene

Dibromochloromethane

Dibromomethane

1 ,2-Dibromo-3-chloropropane

1 ,2-Dibromoethane

1 ,2-Dichlorobenzene

Common

or

alternate

name(s)

TAME

--

Phenyl bromide

Methylene chlorobromide

Dichlorobromomethane

Vinyl bromide

Methyl bromide

Methylethylketone

1-phenylbutane

2-phenylbutane

2-methyl-2-phenylpropane

Phenyl chloride

Ethyl chloride

Vinyl chloride

Methyl chloride

o-Chlorotoluene

/?-Chlorotoluene

~

Methylene bromide

DBCP

EDB

o-Dichlorobenzene

Chemical

Abstract

Services

registry

number

107-13-1

994-05-8

71-43-2

108-86-1

74-97-5

75-27-4

593-60-2

74-83-9

78-93-3

104-51-8

135-98-8

98-06-6

107-05-1

108-90-7

75-00-3

75-01-4

74-87-3

95-49-8

106-43-4

107-05-1

124-48-1

74-95-3

96-12-8

106-93-4

95-50-1

Minimum

reporting

level

(l^g/L)

2

0.1

0.05

0.05

0.1

0.1

0.1

0.1

5

0.05

0.05

0.05

0.05

0.05

0.1

0.1

0.2

0.05

0.05

0.1

0.1

0.1

0.5

0.1

0.05

U.S. Canadian 

drinking drinking 

water water 

standard or standard or 

guideline guideline 

(lilg/L) 1 (|Llg/L)2 

6

-

55

-

10

100

--

10

-

-

-

--

-

100 80

-

2

3

-

-

~

100

--

0.2

0.05

600 200
00 Table 3. Volatile organic compounds analyzed in ground water from the Abbotsford-Sumas aquifer, February 1997, and minim

standards, and freshwater criteria for protection of aquatic life Continued

Volatile organic

compounds

1 ,3-Dichlorobenzene

1 ,4-Dichlorobenzene

trans- 1 ,4-Dichloro-2-butene

Dichlorodifluoromethane

1 ,2-Dichloroethane

cis- 1 ,2-Dichloroethene

trans- 1 ,2-Dichloroethene

1 , 1 -Dichloroethane

1 , 1-Dichloroethene

Dichloromethane

1 ,2-Dichloropropane

1 ,3-Dichloropropane

1 , 1 -Dichloropropene

2,2-Dichloropropane

cis- 1 ,3-Dichloropropene

trans- 1 ,3-Dichloropropene

Diethylether

Diisopropylether

Ethylbenzene

Ethyl-t-butyl ether

2-Ethyl Toluene

Ethyl Methacrylate

Hexachloroethane

Hexachlorobutadiene

2-Hexanone

lodomethane

Common

or

alternate

name(s)

m-Dichlorobenzene

/7-Dichlorobenzene

--

CFC-12

Ethylene dichloride

cis-DCE

trans-DCE

Ethylidene chloride

Methylene chloride

1,2-DCP

-

-

-

-

-

Ethyl ether

-

-

ETBE

o Ethyl Toluene

--

HCBD

-

Methyl iodide

Chemical

Abstract

Services

registry

number

541-73-1

106-46-7

110-57-6

75-71-8

107-06-2

156-59-4

156-60-5

75-34-3

75-35-4

75-09-2

78-87-5

142-28-9

563-58-6

594-20-7

100-61-015

100-61-026

60-29-7

108-20-3

100-41-4

637-92-3

611-14-3

97-63-2

67-72-1

87-68-3

591-78-6

74-88-4

Minimum

reporting

level

(m/L)

0.05

0.05

5.0

0.2

0.05

0.05

0.05

0.05

0.1

0.1

0.05

0.2

0.2

0.05

0.1

0.1

0.1

0.1

0.05

0.1

0.05

1.0

0.05

0.2

5.0

U.S. Canadian

drinking drinking

water water

standard or standard or

guideline guideline

(lilg/L) 1 (|Llg/L)2

600

75 5

-

1,000

5 5

70 5

100

--

7

5 50

5

--

-

-

10

10

--

-

700 2.4

-

--

--

-.

._

0.5
Table 3. Volatile organic compounds analyzed in ground water from the Abbotsford-Sumas aquifer, February 1997, and minimu

standards, and freshwater criteria for protection of aquatic life Continued

Volatile organic

compounds

Isopropyl benzene

p-Isopropyltoluene

Methyl Acrylate

Methyl Acrylonitrile

Methyl tert-butyl ether

Methylbenzene

4-Methyl-2-Pentanone

Methyl Methacrylate

Napthalene

2-Propanol

2-Propanone

n-Propylbenzene

Tetrachloroethene

Tetrachloromethane

Tetrehydrofuran

1,1,1 ,2-Tetrachloroethane

1 , 1 ,2,2-Tetrachoroethane

1 ,2,3,5-Tetramethylbenzene

1 ,2,3,4-Tetramethylbenzene

Tribromomethane

1 ,2,3-Trichlorobenzene

1 ,2,4-Trichlorobenzene

Trichloroethene

Trichlorofluoromethane

Trichloromethane

1,1,1 -Trichloroethane

Common

or

alternate

name(s)

Cumene

p-Cymene

--

--

MTBE

Toluene

Methyl isobutylketone

--

--

Acrolein

Acetone

1-Phenylpropane

Perchloroethylene, PCE

Carbon tetrachloride

-

--

--

Isodurene

Prernitene

Bromoforrn

-

TCE

CFC-11

Chloroform

Methyl chloroform, TCA

Chemical

Abstract

Services

registry

number

98-82-8

99-87-6

96-33-3

126-98-7

163-40-44

108-88-3

108-10-1

80-62-6

91-20-3

107-02-8

67-64-1

105-65-1

127-18-4

56-23-5

109-99-9

630-20-6

79-34-5

527-53-7

488-23-3

75-25-2

87-61-6

120-82-1

79-01-6

75-69-4

67-66-3

71-55-6

Minimum

reporting

level

(V8/U

0.05

0.05

2

2

0.1

0.05

5.0

1

0.2

2

5

0.05

0.2

0.05

5

0.05

0.1

0.05

0.05

0.2

0.2

0.2

0.2

0.1

0.05

0.05

U.S. Canadian 

drinking drinking 

water water 

standard or standard or 

guideline guideline 

(liig/L) 1 (|ig/L)2 

--

--

-

20

1,000 24

-

-

-

--

-

-

5

55

-

70

-

-

-

100

70

5 50

2,000

100

200
Table 3. Volatile organic compounds analyzed in ground water from the Abbotsford-Sumas aquifer, February 1997, and minim

standards, and freshwater criteria for protection of aquatic life-Continued

Volatile organic

compounds

1 , 1 ,2-Trichloroethane

1,1,2-Trichloro1 ,2,2trifluoroethane

1 ,2,3-Trichloropropane

1 ,2,3-Trimethylbenzene

1 ,2,4-Trimethylbenzene

1 ,3,5-Trimethylbenzene

Vinyl Acetate

Styrene

meta & para Xylene

ortho Xylene

Common

or

alternate

name(s)

Vinyl trichloride

CFC-113

--

-

Pseudocumene

Mesitylene

--

Vinyl benzene

-

Chemical

Abstract

Services

registry

number

79-00-5

76-13-1

96-18-4

526-73-8

95-63-6

108-67-8

108-05-4

100-42-5

108-38-3

95-47-6

Minimum

reporting

level

(^g/L)

0.2

0.05

0.2

0.05

0.05

0.2

5.0

0.2

0.05

0.05

U.S.

drinking

water

standard or

guideline

(^g/L) 1

5

-

40

-

-

-

-

100

-

Canadian 

drinking 

water 

standard or 

guideline 

Olg/L)2 

__

-

--

--

..

..

..

300

--

1 Unless otherwise noted, guidelines from U.S. Environmental Protection Agency (1996).

2 Unless otherwise noted guidelines from Health and Welfare Canada (1993).

3 Criteria for the protection of freshwater aquatic life are recommended maximum concentrations in water by National Acade

Academy of Engineers from Now ell and Resek (1994).

4 Guidelines for the protection of freshwater aquatic life are from Canadian Council of Ministers of the Environment (1993).
Table 4. Pesticide compounds analyzed in ground water from the Abbotsford-Sumas aquifer, February 1997, and minimum re

standards, and freshwater criteria for protection of aquatic life

[|0,g/L, micrograms per liter; U.S., United States; H, herbicide; I, insecticide; M, metabolite; , no value]

Pesticide

compound

Trade

or

common

name(s)

Type

of

pesticide

Chemical

Abstract

Services

registry

number

Minimum

reporting

level

(Hg/L)

U.S.

drinking

water

standard

(Hg/L) 1

Canadian

drinking

water

standard

(u.g/L)2

Gas Chromatography/Mass Spectrometry analytical data

Alachlor

Atrazine

Azinphos-methyl

Benfluralin

Butylate

Carbaryl6

Carbofuran6

Chlorpyrifos

Cyanazine

DCPA

p,p'-DDE

Desethylatrazine9' 10

Diazinon

Dieldrin

2,6-Diethylanaline

Disulfoton

EPTC

Ethalfluralin

Ethoprop

Fonofos

alpha-HCH

gamma-HCH

Linuron6

Malathion

Methyl parathion

Lasso

AAtrex

Guthion

Balan, Benefin

Sutan +, Genate Plus

Sevin, Savit

Furadan

Lorsban/Dursban

Bladex

Dacthal

none

none

several

PanoramD-31

none

Di-Syston

Eptam, Eradicane

Sonalan, Curbit EC

Mocap

Dyfonate

none

Lindane

Lorox, Linex

several

Penncap-M

H

H

I

H

H

I

I

I

H

H

M

M

I

I

M

I

H

H

I

I

M

I

H

I

I

15972-60-8

1912-24-9

86-50-0

1861-40-1

2008-41-5

63-25-2

1563-66-2

2921-88-2

21725-46-2

1861-32-1

72-55-9

6190-65-4

333-41-5

60-57-1

579-66-8

298-04-4

759-94.4

55283-68-6

13194-48-4

944-22-9

319-84-6

58-89-9

330-55-2

121-75-5

298-00-0

0.002

0.001

0.001

0.002

0.002

0.003

0.003

0.004

0.004

0.002

0.006

0.002

0.002

0.001

0.003

0.017

0.002

0.004

0.003

0.003

0.002

0.004

0.002

0.005

0.006

2

3

~

-

350

700

40

20

4 1

54,000

80.1

50.6

80.002

50.3

-

5 10

80.006

0.2

200

52

._

60

20

-

90

90

90

10

20

~

-

-

-

--

190

-
Table 4. Pesticide compounds analyzed in ground water from the Abbotsford-Sumas aquifer, February 1997, and minimum re

standards, and freshwater criteria for protection of aquatic life Continued

Pesticide

compound

Trade

or

common

name(s)

Type

ofpesticide

Chemical

Abstract

Services

registry

number

Minimum

reporting

level

QigfL)

Gas Chromatoeraohv/Mass Soectrometrv analytical

Metolachlor

Metribuzin

Molinate

Napropamide

Parathion

Pebulate

Pendimethalin

cw-Permethrin

Phorate

Prometon

Pronamide

Propachlor

Prop anil

Propargite

Simazine

Tebuthiuron

Terbacil

Terbufos

Thiobencarb

Triallate

Trifluralin

Dual, Pennant

Lexone, Sencor

Ordram

Devrinol

several

Tillam

Prowl,Stomp

Ambush, Pounce

Thimet, Rampart

Pramitol

Kerb

Ramrod

Stampede

Comite, Omite

Aquazine, Princep

Spike

Sinbar

Counter

Bolero

Far-Go

Treflan, Trilin

H

H

H

H

I

H

H

I

I

H

H

H

H

I

H

H

H

I

H

H

H

51218-45-2

21087-64-9

2212-67-1

15299-99-7

56-38-2

1114-71-2

40487-42-1

57608-04-5

298-02-2

1610-18-0

23950-58-5

1918-16-7

709-98-8

2312-35-8

122-34-9

34014-18-1

5902-51-2

13071-79-9

28249-77-6

2303-17-5

1582-09-8

0.002

0.004

0.004

0.003

0.004

0.004

0.004

0.005

0.002

0.018

0.003

0.007

0.004

0.013

0.005

0.01

0.007

0.013

0.002

0.001

0.002

U.S.

drinking

water

standard

Oig/L) 1

data Continued

70

5 100

~

-

-

-

5 100

550

5 90

-

-

4

5500

5 90

50.9

-

55

Canadian

drinking

water

standard

Oig/L)2

50

80

-

-

50

-

-

2

_

..

-

-

-

10

__

1

-

230

45

Hieh-Performance Liauid Chromatosraohv analytical data

2,4-D

2,4-DB

several

none

H

I

94-75-7

94-82-6

0.15

0.24

70

-

100

~
Table 4. Pesticide compounds analyzed in ground water from the Abbotsford-Sumas aquifer, February 1997, and minimum re

standards, and freshwater criteria for protection of aquatic life Continued

Trade 

or 

Pesticide common 

compound name(s)

Type 

of 

pesticide

Chemical 

Abstract 

Services 

registry 

number

Minimum 

reporting 

level 

(Hg/L)

U.S. 

drinking 

water 

standard

(l^g/L) 1

Canadian 

drinking 

water 

standard 

(|ig/L)2 

Hieh-Performance Liauid Chromatoeraohv analytical data Continued

2,4,5-T

2,4-5-TP9

3-Hydroxycarbofuran9

Acifluorfen

Aldicarb9' 10

Aldicarb sulfone9 ' 10

Aldicarb sulfoxide >10

Bentazon 

Bromacil

Bromoxynil 

Carbaryl6'9 

Carbofuran6'9

Chloramben 

Chlorothalonil 10

Clopyralid

Dacthal,

mono-acid) 

Dicamba

Dichlorprop

Dinoseb

Diuron10

DNOC

Fenuron

Fluometuron

Linuron6

MCPA

several

Si 1 vex

none

Blazer

Temik

Standak

none

Basagran 

Hy var, Urox B

Buctril, Brominal 

Sevin, Savit 

Furadan

Amiben, Vegiben 

Bravo

Stinger, Lontrel

none 

Banvel

2,4-DP, Seritox 50

DNBP, Dinitro

Karmex, Direx

Trifocide, Elgetol 30

Beet-Kleen

Flo-Met, Cotoran

Lorox, Linex

Metaxon, Kilsem

H

H

M

H

I

M

M

H 

H

H 

I 

I

H 

F

H

M 

H

H

H

H

I, F, H

H

H

H

H

93-76-5

93-72-1

1563-38-8

50594-66-6

116-06-3

1646-88-4

1646-87-3

25057-89-0 

314-40-9

1689-84-5 

63-25-2 

1563-66-2

133-90-4 

1897-45-6

1702-17-6

887-54-7 

1918-00-9

120-36-5

88-85-7

330-54-1

534-52-1

101-42-8

2164-17-2

330-55-2

94-74-6

0.035

0.021

0.014

0.035

0.55

0.1

0.021

0.014 

0.035

0.035 

0.008 

0.12

0.42 

0.48

0.23

0.017 

0.035

0.032

0.035

0.02

0.42

0.013

0.035

0.018

0.17

570

50

8T

7

7

7

200 

590

5700 

40

5 100 

8 1.5

-

5200

-

7

5 10

-

590

5 10

280

9

5 

90 

90

-

120 

-

10

150 

..

_.
Table 4. Pesticide compounds analyzed in ground water from the Abbotsford-Sumas aquifer, February 1997, and minimum re

standards, and freshwater criteria for protection of aquatic life Continued

Pesticide

compound

Trade

or

common

name(s)

Type

of

pesticide

Chemical

Abstract

Services

registry

number

Minimum

reporting

level

(fig/L)

U.S. Canadian

drinking drinking

water water

standard standard

(Hg/L) 1 (Hg/L)2

Hieh-Performance Liauid Chromatoeraohv analytical data-Continued

MCPB

Methiocarb

Methomyl

Neburon

Norflurazon

Oryzalin 10

Oxamyl

Picloram9

Propham

Propoxur

Triclopyr

Can-Trol, Thistrol

Grandslam, Mesurol

Lannate, Nudrin

Neburex, Noruben

Evital, Solicam

Surflan

Vydate

Tordon

Chem-Hoe, IPC

Baygon

Garlon, Grazon

H

I

I

H

H

H

I

H

H

I

H

94-81-5

2032-65-7

16752-77-5

555-37-3

27314-13-2

19044-88-3

23135-22-0

1918-02-1

122-42-9

114-26-1

55335-06-3

0.14

0.026

0.017

0.015

0.024

0.31

0.018

0.05

0.035

0.035

0.25

__

5200

__

200

500 190

5 100

1 Unless otherwise noted, guidelines from USEPA October 1996 drinking water regulations and health advisory EPA 822-B-96-002

2 Unless otherwise noted guidelines from Guidelines for Canadian Drinking Water Quality, fifth edition 1993 Health and Welfare C

Group-Publishing, Ottawa, Canada K1A-059.

3 Criteria for the protection of freshwater aquatic life are recommended maximum concentrations in water by National Academy of 

Engineers from Nowell and Resek (1994).

4 Guidelines for the protection of freshwater aquatic life are Canadian Water Quality Guidelines from Canadian Council of Ministe

5 U.S. Environmental Protection Agency lifetime-health advisory for a 70-kilogram adult, from Nowell and Resek (1994).

6 Analyzed by both gas chromatography/mass spectrometry and high-performance liquid chromatography methods.

7 Interim guidelines for the protection of freshwater aquatic life are Canadian Water Quality Guidelines from Canadian Council of 

8 U.S. Environmental Protection Agency risk-specific dose health advisory associated with a cancer risk of 10-6 (one in a million), 

9 Pesticide target analyte is heat and light sensitive and therefore susceptible to degradation. This may result in poor overall recove

Quality Assurance Committee for the Schedule 2050/2051 Pesticide Analysis Method, written commun., 1995).

10 Low recovery of matrix spike (20-60 percent) indicates potential for false negative results.
between the submersible pump and the sampling 

apparatus. All field supplies, bottles, reagents, and 

surrogates that were used for sample collection were 

tested for contamination and approved by either the 

manufacturer or the USGS National Water Quality 

Laboratory.

Field instruments were calibrated at the beginning of each day and between every second sampling 

site. At each site, water levels and down-hole water 

temperature were measured before installation of 

submersible-pump sampling equipment. The sampling 

pump was positioned at or just above the well's 

screened interval and water was pumped at a rate of 

about 4 to 8 liters per minute. Each well was initially 

pumped to remove at least three casing volumes after 

which field parameters were monitored until stable 

readings of pH, specific conductance, temperature, and 

dissolved oxygen were obtained. These parameters 

were measured in a flow-through chamber so that 

ground water was not exposed to the atmosphere prior 

to monitoring. Stable readings were defined as variations about a central value of less than or equal to 

0.1 pH units, 0.2°C (degrees Celsius) for temperature, 

plus or minus 3 percent for specific conductance, and 

0.3 mg/L (milligram per liter) for dissolved oxygen 

between successive readings 3 minutes apart. 

Dissolved oxygen readings of less than 1 mg/L were 

confirmed using a Chemetrix rhodazine dye method 

(White and others, 1990). Field alkalinity of a filtered 

sample was determined at each site by incremental 

titrations.

Unfiltered water samples were collected for 

analysis of volatile organic compounds in 40-milliliter 

septum vials, which were filled slowly to avoid aeration 

and then preserved with one to three drops of hydrochloric acid to achieve a pH of from 1.7 to 2.0. Pesticide samples were filtered through a 0.7-micrometer 

glass fiber filter and field-extracted from the filtrate by 

pumping through solid-phase extraction cartridges as 

described by Shelton (1994) and Sandstrom and others 

(1992). Samples for analysis of trace elements, 

common ions, and nutrients were filtered using a 

0.45-micrometer cellulose filter. Trace elements and 

cation samples were preserved with nitric acid to a pH 

of less than 2; samples for analysis of mercury were 

preserved with 10 milliliters of potassium dichromate. 

Samples for VOC, pesticide, nutrient, and organic 

carbon analysis were chilled to 4 degrees Celsius or 

less and shipped to the laboratory by overnight courier.

All samples received by the laboratory were analyzed 

within accepted holding times.

Following the collection of these samples, the 

submersible pump equipped with teflon discharge lines 

was decontaminated using 0.1 percent solution of 

Liquinox soap and deionized water following the 

general procedures described by Koterba and others 

(1995), however, the methanol rinse was omitted to 

minimize the potential for contamination of dissolved 

organic carbon samples. A second submersible pump 

with a discharge line made of refrigeration-grade 

copper tubing suitable for collecting CFC samples was 

installed in the well for collection of CFC samples. 

CFC samples were collected in triplicate using methods described by Busenberg and Plummer (1992).

Laboratory Procedures

Concentrations of common ions and trace 

elements were analyzed by inductively coupled plasma 

(ICP), with the exception of lead (analyzed by graphite 

furnace atomic absorption), mercury (analyzed by cold 

vapor atomic absorption), and chloride and sulfate 

(analyzed by ion-exchange chromatography). Minimum reporting levels and compounds quantified by 

these methods are listed in table 2. The analytical 

methods used are described further by Fishman (1993).

Concentrations of VOCs were determined by 

purge and trap gas chromatography with electron 

impact mass spectrometry (GC/MS) following U.S. 

Environmental Protection Agency (EPA) Method 

524.2 (Rose and Schroeder, 1995; Connor and others, 

1998). Minimum reporting levels and compounds 

quantified by this method are listed in table 3 along 

with corresponding United States and Canadian 

drinking water and freshwater guidelines (U.S. 

Environmental Protection Agency, 1996; Health and 

Welfare Canada, 1993; and Canadian Council of 

Ministers of the Environment, 1993). Pesticides were 

analyzed utilizing solid-phase extraction techniques 

and gas chromatography and mass spectrometry 

(GC/MS) analysis with selected ion monitoring as 

described by Werner and Johnson (1994), Zaugg and 

others (1995) and Werner and others (1996). Minimum 

reporting levels and compounds quantified by this 

method are listed in table 4. CFCs were analyzed by 

gas chromatography following procedures described 

by Busenberg and Plummer (1992).

15
QUALITY ASSURANCE

Procedures were followed to insure the collection of data with known and acceptable quality. These 

procedures included the use of non-contaminating 

sample collection techniques described in the previous 

section, the collection of quality assurance and control 

(QA/QC) samples, and review of laboratory data by 

laboratory and project personnel.

Quality-Assurance/Quality-Control 

Samples

Quality-control samples included two equipment-blank samples and one replicate sample of 

organic constituents collected as part of this study, and 

review of field-matrix spike data collected from a concurrent study. Laboratory QA/QC checks included the 

analysis of double blind reference materials, daily 

blanks, daily standards, daily instrument tuning, surrogate spike recovery, and other quality-control check 

samples as described by Pritt and Raese (1995). Analyte recovery and analytical precision and accuracy are 

described by Rose and Schroeder (1995), Werner and 

Johnson (1994), and Werner and others (1996).

Equipment blanks for VOCs were collected 

immediately before and after the 10 well-water 

samples were collected. Certified VOC-free water was 

used to process the equipment blanks. Laboratory 

grade deionized water was used to wash and decontaminate the equipment and was analyzed for VOCs, trace 

elements, and common ions prior to conducting field 

work. The VOC sample vials were precleaned and certified by the manufacturer to be free of VOCs; however, 

the minimum detection values shown on the certificate 

of analysis for the VOC sample vials was often larger 

than the minimum detection level reported for the analytical methods used by the NWQL. Equipment blanks 

for pesticides were collected immediately before, midway through the sampling, and after the 10 well-water 

samples were collected. The pesticide equipmentblank sample collected midway through this sampling 

was analyzed and contained no detectable concentrations of pesticides, as did the previous six pesticide 

equipment-blank samples obtained with this sampling 

equipment for other studies, thus no other pesticide 

equipment-blank samples were analyzed.

Short-term variability due to variations in 

sampling technique, variability in analytical technique, 

and short-term in-situ aquifer chemical variations

were assessed by the repeat sampling of one well (well 

91-15) 3 days apart following the initial sample collection. Estimates of the bias and variability in the pesticide and VOC data caused by analyte degradation, the 

effects of ground-water matrix, and the analytical 

processes were assessed using data from two spikereplicate sample sets collected from a concurrent study 

which included the Abbotsford-Sumas aquifer. The 

spike-replicate sample sets were collected in September and December of 1996 as part of the National Water 

Quality Assessment (NAWQA) of the Puget Sound 

region. The sample sets were collected from shallow 

wells screened in glacial-outwash aquifers; one site 

located in the Abbotsford-Sumas aquifer and the other 

from a similar site about 200 kilometers south of the 

aquifer. In these samples, three replicate environmental samples were collected; known concentrations, 

typically 0.1 |lg/L (microgram per liter) of many of the 

organic compounds were added to two of the replicate 

samples.

Data Quality Assessment

Review of quality-assurance data showed that 

overall, the majority of the 210 water-quality parameters examined showed little significant bias or 

variability; however, low concentrations of four VOCs 

and three trace elements were detected in equipmentblank samples indicating the occurrence of sampling or 

analytical bias for those constituents. All laboratory 

results are reported in tables 5, 6, and 7; results that 

may be affected by sampling or analytical bias are 

flagged with a "V". Field-matrix spike information 

(data not shown) showed low recoveries for three compounds not detected in the environmental samples and 

high recovery for one compound that was detected.

Three compounds (1-Napthal, Dichlobenil, and 

Esfenvalerate) with matrix spike recoveries of less than 

20 percent were removed from the analyte list. The 

concentration of Tebuthiuron, which showed a recovery greater than 140 percent, was flagged with the "V" 

code to indicate potential bias. Other organic 

compounds (Aldicarb, Aldicarb sulfone, Aldicarb 

sulfoxide, Chlorothalonil, Desethylatrazine, Diuron, 

and Oryzalin) that were not detected in the groundwater samples showed recoveries between 20 and 60 

percent. A notation was added to the analyte list (table 

4) indicating low recoveries and the potential for falsenegative detections.

16
Table 5. Volatile organic compounds and pesticides detected in samples of shallow ground water from the transboundary region of the Abbotsford-Sumas aquifer, February 1997 (Complete analyte lists are in tables 3 and 4) 

[E, indicates some laboratory quantitative uncertainty and thus the value is flagged as estimated; V, indicates potential bias in 

environmental sample based on quality control data associated with environmental samples. All concentrations in micrograms per liter; 

Ug/L, micrograms per liter; --, constituent not detected]

Organic 

compound 

Date in 1997

Trichlorfluormethane

Carbon disulfide

1,1 Dichloro

ethane

Methyl tertbutyl ether

Chloroform

1,1,1 Trichloro

ethane

Trichloroethylene

l,2Dichlorpropane

trans- 1 ,3 Dichloropropene

cis- l,3Dichloroproene

1,3 Dichloropropane

l,2,3Trichloropropane

Tetrachloro

ethylene

meta & para

Xylene

1 ,2 Dibromochloropropane

Atrazine

Carbofuran

Desethyl

atrazine

Dinoseb

Napropamide

Oxamyl

Simazine

Tebuthiuron

Reporting 

level 

Olg/L)

0.1

0.05

0.05

0.1

0.05

0.05

0.05

0.05

0.1

0.1

0.05

0.02

0.05

0.05

0.5

0.001

0.12

0.002

0.035

0.003

0.018

0.005

0.01

91-15 

2/4

0.20

-

-

E.09

E.01

E.04

-

E.06

-

-

~

-

-

-

E.07

E.004

-

E.006

0.06

0.011

0.41

0.084

V.012

Well name

FTC91-15 91-13 1-24 ABB2 ABB4 ABBS

2/7 2/4 2/6 2/5 2/3 2/6

0.19 E.03

..

E.07

E.09 -- E0.01

E.01 E.02 -- -- E.02

E.04 0.54 - 0.14 E.009

E.005 -

E.07 0.11 E.04 0.15 0.14 0.24

..

--

..

E.01

-

E.07

E.004 - E.006 -

E.002 --

E.006 - E.005 -

0.06

0.011 -

0.45 - -- - 1.2

0.082 -

V.012 -

Equipment

BCME- 94- 94- blanks 

B-20 LEH SR-29

2/5 2/7 2/3 1/31 2/10

-

E.005 E.007 - E.02

..

E.01

..

..

0.48 0.37

E.03

E.02

E.08 E.05

0.13 E.07

--

E.007

-

E.002

..

E.004

..

-

0.45 23

0.021 0.021

..

COMPOUNDS DETECTED IN SAMPLE WATER MOST LIKELY THE RESULT OF SAMPLING OR ANALYTICAL ARTIFACTS

Acetone (2-propa- 5.0 -- -- -- VE1.1 VE1.0 -- VE0.8 - VE0.6 - E5 El.

none) 

Toluene (Methyl- 0.05 VE.03 VE.03 VE.04 VE.02 VE.03 VE.03 VE.03 VE.01 VE.03 VE.01 ~* E.07

benzene)

1,1,2-Trichloro- 0.05 VE.006 - VE.01 VE.01 VE.01 VE.02 - -- - VE.02 0.12 E.04 

1,2,2-triflouroethane(CFC-113) 

1,2,4-Trimethyl 0.05 V.49 V.37 V.52 V.25 V.20 V.I V.30 V.29 V.44 V.27 0.18 0.35

Benzene

* Toluene was reported at 0.005 in both laboratory procedure blanks associated with this sample and thus not estimated below the detection level.

17
Table 6. Field measurements and concentrations of inorganic constituents in transboundary ground water from the

Abbotsford-Sumas aquifer

[|lS/cm, microsiemens per centimeter; mg/L, milligrams per liter; |lg/L, micrograms per liter; <, less than; , no data]

Water-quality constituent

Date-month/day/ 1 997

Time

Water temperature, degrees Celsius

Specific conductance, |iS/cm

pH, Standard units

Dissolved oxygen, mg/L

Alkalinity, mg/L as CaCO3

Calcium, mg/L as Ca

Magnesium, mg/L as Mg

Sodium, mg/L as Na

Potassium, mg/L as K

Bicarbonate, mg/L as HCO^

Sulfate, mg/L as SO4

Chloride, mg/L as Cl

Fluoride, mg/L as F

Silica, mg/L as Si

Sum of dissolved constituents, mg/L (TDS)

Residue on evaporation, mg/L (ROE)

Ion Balance, percent difference

Nitrite nitrogen, mg/L as N

Nitrate plus nitrite nitrogen, mg/L as N

Ammonia nitrogen, mg/L as N

Ammonia plus organic, mg/L as N

Phosphorus, mg/L as P

Phosphate, ortho, mg/L as P

Organic carbon, mg/L as C

Antimony, fo,g/L as An

Arsenic, fig/L as As

Aluminum, fig /L as Al

Barium, fig/L as Ba

Beryllium, fig/L as Be,

Bromide, fig/L as Br

Cadmium, fo,g/L as Cd

Chromium, fo,g/L as Cr

Cobalt, fig/Las Co

Copper, ug/L as Cu

Iron, ug/L as Fe

Lead, fig/L as Pb

Manganese, fo,g/L as Mn

Mercury, fo,g/L as Hg

Molybdenum, fig/L as Mo

Nickel, |4,g/L as Ni

Selenium, fig/L as Se

Silver, fo,g/L as Ag

Uranium, fig/L as U

Zinc, fig/L as Zn

91-13

2/4

0900

11.5

300

6.2

5.2

35

31

7.8

10

1.2

42

34

13

<0.1

22

205

190

-2.39

0.02

15

<0.015

<0.2

<0.01

<0.01

1.1

<1

<1

V4

8

<1

30

<1

2

<1

<1

<3

<1

<3

<0.1

<1

<1

<1

<1

<1

V3

91-15

2/4

1300

11.6

296

5.9

8.4

18

31

6.5

9.6

2.8

21

28

14

<0.1

13

196

180

-1.37

0.02

18

<0.015

<0.2

<0.01

<0.01

-

<1

<1

V12

9

<1

30

<1

1

<1

<1

<3

<1

3

<0.1

<1

<1

<1

<1

<1

VI

91-15

2/7

0930

11.5

295

5.8

8.0

18

29

6.5

12

2.8

22

28

14

<0.1

13

196

186

-1.28

<0.01

18

<0.015

<0.2

<0.01

<0.01

-

<1

<1

V13

10

<1

20

<1

<1

<1

<1

<3

<1

3

<0.1

<1

<1

<1

<1

<1

<1

94-LEH

2/7

1300

9.8

716

5.7

10.3

6.1

88

17

7.2

13

7.4

41

28

<0.1

12

508

477

-1.17

<0.01

67

<0.015

<0.2

<0.01

<0.01

0.8

<1

<1

V27

225

<1

30

<1

<1

<1

<1

23

<1

11

<0.1

<1

1

<1

<1

<1

V4

94- 

SR-29

2/3

1000

10

298

6.8

7.2

48

32

8.7

6.3

1.2

57

16

6.5

<0.1

20

200

187

-2.66

0.02

18

0.07

<0.2

<0.01

<0.01

-

<1

1

V3

17

<1

1,100

<1

2

<1

<1

<3

<1

<1

<0.1

<1

<1

<1

<1

<1

VI

18
Table 6. Field measurements and concentrations of inorganic constituents in transboundary ground water from the 

Abbotsford-Sumas aquifer Continued

ABB2

2/5

0900

11.0

179

5.9

8.2

24

15

2.7

13

0.9

29

19

7

15

121

114

-1.38

0.02

8.0

<0.015

<0.2

<0.01

<0.01

<1

<1

V12

20

<1

80

<1

<1

<1

<1

11

<1

2

<0.1

<!

<j

<1

V<1

ABB4

2/3

1500

12.5

391

6.4

7.2

48

44

12

8.8

1.5

59.0

27

13

23

266

248

-0.47

0.02

24

<0.015

<0.2

<0.01

<0.01

0.5

<1

<1

V8

13

<1

30

<1

1

<1

<1

53

<1

2

<0.1

VI

<1

<1

V2

ABB5

2/6

1000

10.6

324

5.7

8.9

14

35

6.7

5.7

0.8

17.0

19

9.4

15

219

210

-5.19

<0.01

27

<0.015

<0.2

<0.01

<0.01

0.5

<1

<1

V7

6

<1

30

<1

<1

<1

<1

13

<1

3

<0.1

<!

<J

<1

VI

FTC-1-24

2/6

1400

8.5

420

6.3

0.0

62

49

15

8.8

4.3

76.1

130

9.6

16

270

273

0.36

0.01

<0.05

<0.015

<0.2

<0.01

<0.01

1.0

<1

2

V4.0

36

<1

30

<1

<1

<1

<1

920

<1

130

<0.1

V4

<}

<1

V<1

BCMEB-20

2/5

1200

8.0

405

5.7

10.4

13

47

7.8

5.3

5.3

16

19

13

11

274

255

-2.59

0.03

36

<0.015

<0.2

<0.01

<0.01

0.5

<1

<1

V17

131

<1

20

<1

<1

<1

<1

<3

<1

5

<0.1

<!

<}

<1

V<1

Equipment 

blank

1/31

1200

2.0

1.9

<0.02

<0.01

<0.2

<0.1

<0.1

<0.1

<0.01

3.0

-

<1

<1

4

<1

<1

<0.01

<1

<1

<1

<1

<3

<1

<l

<l'

2

<{

<1

5

Laboratory 

Equipment grade 

blank water

2/10 12/13

1200 0900

2 1

1.5

<0.02 <0.002

<0.01 <0.001

<0.2 <0.025

<0. 1

._

<0. 1

<0.1

<0.01 <0.02

._

<1

._

<0.001

<0.05

0.019

<0.001

._

.-

<1 <0.2

<1

4 <0.3

<1 <0.2

<1 <0.2

<0.01

<1 <0.3

<1 <0.2

<1 <0.2

<1 <0.2

<3 <0.3

<1 <0.3

<1 <0.1

<1 <0.2

<1 <0.5

<1 <0.2

<1 <0.2

5 <0.5

19
Variability in analyte concentrations reported in 

the replicate samples was generally low. Because the 

duration between replicate samples was 3 days, the 

observed variations in the replicate data could be due to 

either short-term temporal variation in the groundwater quality, variations due to sampling and handling, 

or variations due to laboratory analysis. All constituents of the two samples, except dissolved organic carbon, were analyzed in different batch lots. Constituent 

concentrations for replicate samples are shown sideby-side in tables 5 and 6, and show little variation. 

Identical laboratory results were reported for 95 

percent of VOC and pesticide samples, 75 percent of 

trace-element samples, 71 percent of common ion and 

nutrient samples, and 20 percent of field parameters. In 

cases where different concentrations were reported, the 

relative percent difference between the samples was 

generally less than 10 percent.

Zinc, nickel, and aluminum were detected in 

equipment-blank samples at 5, 2, and 3 |Hg/L, respectively. Nickel was detected in one sample at 4 |Hg/L and 

in one blank sample at 2 |Hg/L. Zinc and aluminum 

have been shown to leach from the glass ampules used 

to store the nitric acid used in preserving trace-element 

samples and this leaching is suspected as the source of 

this contamination. The environmental concentrations 

of zinc were between less than 1 to 3.5 |Lig/L; thus it is 

possible that zinc and nickel were not present in samples where they were reported. The reported concentrations of aluminum were between 3 to 27 |ng/L and, 

because of the bias shown in the blank samples, are 

likely to be somewhat larger than actual concentrations 

present in ground water of the aquifer. The laboratory 

results of the zinc, nickel, and aluminum analyses were 

tabulated as reported but were flagged with a "V" to 

indicate potential bias.

Four VOCs that were detected in equipmentblank samples and ground-water samples were acetone 

(2-propanone), toluene (methylbenzene), 1,1,2- 

trichloro-l,2,2-triflouroethane, and 1,2,4-trimethylbenzene. For three of these compounds, values 

estimated by the NWQL were below the MRL. The 

compound 1,2,4-trimethylbenzene was present at 

concentrations above the MRL in all ground-water 

samples and in both pre- and post-sampling equipment 

blanks. The concentrations in the two equipmentblank samples were 0.18 and 0.35 |Hg/L, while concentrations in the ground-water samples were in a similar 

range, from 0.1 to 0.52 |Hg/L. Because of this sampling 

bias, data for 1,2,4-trimethylbenzene is interpreted as

not present in the ground water at concentrations 

greater than 1 |Hg/L. 1,2,4-trimethylbenzene is a 

common component of gasoline. The laboratory 

results of these four VOCs were tabulated as reported 

but were flagged with a "V" to indicate potential bias.

WATER-QUALITY RESULTS

For each sample, 210 water-quality parameters 

were measured. Most of these had concentration 

values that were less than the MRL. The data are presented as two groups. Inorganic constituents including 

common ions, trace elements, nutrients, and the field 

parameters are the first group. Organic compounds are 

the second group, which includes 87 VOCs, 82 pesticides, and the 3 CFC compounds (trichlorofluoromethane, CFC-11; dichlorodifluoromethane, CFC-12; 

and l,l,2-trichloro-l,2,2-trifluoroethane, CFC-13). 

The MRL is the concentration at which a quantitative 

value for the concentration can be reliably determined. 

The laboratory analytical methods can generally detect 

the presence of a compound at concentrations smaller 

than the reporting level; however, analytical uncertainty is larger at these lower concentrations, and thus 

only qualitative estimates are reported in these 

instances. In instances when a compound was detected 

below the MRL, the laboratory provided an estimated 

concentration that is flagged with an "E" to denote the 

estimated concentration. The "E" flag was also used 

for results in instances where matrix effects or a 

calibration curve was exceeded.

Nutrients, Common Ions, and Trace 

Elements

Nitrate concentrations ranged from <0.05 to 

67 mg/L as nitrate nitrogen and were above the drinking water standard or guideline of 10 mg/L (U.S. 

Environmental Protection Agency, 1996; Health and 

Welfare Canada, 1993) at seven of nine wells. Nitrate 

contamination in this aquifer is well documented and 

these results were not unexpected. The concentrations 

of other common ions, trace elements, and nutrients in 

the Abbotsford-Sumas aquifer are generally small 

resulting in ground water having total dissolved solids 

typically less than 275 mg/L. Calcium was the cation 

most prevalent in all of these ground-water samples, 

while the most prevalent anion was either nitrate,

20
sulfate, or bicarbonate. Most trace-element concentrations were below the MRL. Zinc, nickel, and aluminum were detected in equipment blanks as discussed 

earlier and are estimated values. Aluminum, arsenic, 

chromium, manganese, nickel, and zinc were found at 

or near the MRL in several of the ground-water samples. All samples had concentrations of barium and 

bromide at concentrations greater than five times the 

MRLs, while most also had similar concentrations of 

iron and manganese. The largest trace-element 

concentration was 1,100 |ig/L of bromide in well 

94-SR-29.

The ground water is slightly acidic having pH 

values between 5.7 to 6.8 and is generally well oxygenated with dissolved oxygen concentrations typically 

greater than 7 mg/L. The water quality in well 

FTC-1-24, which is located adjacent to Fishtrap Creek, 

is anomalous compared to the other wells. It has low 

concentrations of nitrate and dissolved oxygen, and 

generally has higher concentrations of iron, manganese, and sulfate.

Pesticides and Volatile Organic 

Compounds

Twenty-seven pesticides and volatile organic 

compounds (VOCs) were detected by the laboratory 

analysis (table 5). Only 23 of these detected compounds are likely present in the ground water of the 

Abbotsford-Sumas aquifer. Four of the detected VOCs 

are likely the result of sampling and analytical bias and 

were discussed in the previous section on data quality 

assessment. The concentrations of detected compounds ranged from 0.01 to 23 |ig/L. None of the 

reported concentrations of VOCs and pesticides (table 

5) exceed the drinking water guidelines or standards for 

those compounds listed in tables 3 and 4. Since most 

of the organic compounds that were analyzed were not 

detected, table 5 presents data only for those compounds with detectable concentrations.

Comparison of the concentrations of detected 

compounds in replicate samples from well 91-15 

shows good agreement among replicates (table 5), 

indicating that variability due to sampling and analysis 

was small. Most of the compounds detected were at 

concentrations very near their detection limits. Of the 

15 compounds detected in both samples, 10 had identical concentrations in the samples collected 3 days 

apart. The relative percent difference in concentrations 

for the five compounds with differing concentrations

ranged from 2 to 28 percent. However, if 1,2,4-trimethylbenzene, which was thought to be an artifact of 

sampling, is excluded, then the range for the relative 

percent difference is 2 to 15 percent, averaging about 8 

percent.

The number of detections of organic compounds 

in the ground-water samples was typically from three 

to eight compounds in each sample; however, in the 

deepest well, 94-SR-29, no organic compounds were 

detected. The most frequently detected organic compound was 1,2-dichloropropane (1,2-DCP), which was 

observed in all but the deepest well (94-SR-29) at concentrations ranging from 0.04 to 0.48 jlg/L, typically 

greater than two times the MRL. In the two wells 

with 1,2-DCP concentrations greater than 0.35 jig/L, 

additional chlorinated propanes were also detected. 

Oxamyl was found in four wells at concentrations 

ranging from 0.41 to 23 |ig/L. Simazine, atrazine, and 

desethylatrazine were each present in three wells.

Chlorofluorocarbons

CFCs are synthetic organic compounds that are 

entirely of man-made origin. The primary use of these 

compounds is as a refrigerant, which began in the 

1930's. The ultimate environmental fate of CFCs is 

release to the atmosphere, where CFCs can dissolve 

into precipitation that recharges aquifers. Atmospheric 

concentrations of CFCs have increased steadily from 

earliest detections until peak concentrations were 

reached in 1993 and 1994. Maximum atmospheric 

CFC concentrations for the period prior to 1997 are: 

CFC-11,276 parts per trillion, volume (pptv); CFC-12, 

544 pptv; and CFC-113, 84.8 pptv (Eurybiades 

Busenberg, U.S. Geological Survey, written commun., 

1997). CFCs have been used to date some ground 

water recharged after 1940 based on the presumption 

that the source of the CFCs in the ground water is from 

atmospheric equilibration of CFCs present in the atmosphere at the time precipitation recharged the aquifer 

(Busenberg and Plummer, 1992). Concentrations 

larger than the maximum atmospheric concentrations 

indicate CFCs from sources in addition to atmospheric 

equilibration.

CFC concentrations were measured in water 

samples from seven wells and the equilibrium vapor 

phase concentrations, which can be compared to 

atmospheric concentrations, were computed following 

the procedures of Busenberg and Plummer (1992).

21
Table 7. Concentration of chlorofluorocarbons in ground-water samples and calculated equalibrium vapor phase

concentration

[mg/L, milligrams per liter; pg/kg, picograms per kilogram; pptv, parts per trillion by volume]

CFC-11

Sample 

Well name date

91-15 2/4/97

91-13 2/4/97

FTC-1-24 2/27/97

ABB4 2/3/97

ABBS 2/6/97

BCME- 2/5/97

B-20

94-SR-29 2/3/97

Dissolved

Sample oxygen 

time (mg/L)

11:23 8.4

11:39

11:47

13:30 5.2

13:45

13:53

12:30 <0.1

12:41

17:00 7.2

17:16

17:30

11:30 8.9

11:38

11:52

14:05 10.4

14:30

11:25 7.2

11:38

12:05

Concentration in

sample

(pg/kg)

15,900

16,300

15,500

24,000

23,900

23,000

7.9

8.2

1,280

1,280

1,210

613

605

597

676

663

256

255

257

Calculated

atmospheric

concentration 

(pptv)

5,506

5,660

5,380

8,310

8,290

7,980

2.7

2.8

443

443

420

212

210

207

234

230

88.8

88.6

89

CFC-12

Concentration in

sample 

(pg/kg)

791

796

622

3,290

3,330

3,000

97.4

106

2,970

2,900

2,920

382

382

330

464

430

441

437

467

Calculated

atmospheric

concentration 

(pptv)

1,200

1,210

944

5,000

5,050

4,550

148

161

4,510

4,410

4,440

580

579

501

703

649

669

664

709

CFC-13

Concentration in

sample 

(pg/kg)

49.3

50.8

35.9

182

189

99.7

24.4

4.4

75

61.5

76.1

76.6

77.8

66.1

157

11.2

140

143

81.1

Calculated

atmospheric

concentration 

(pptv)

41.1

42.3

29.9

151.4

158

83

20.3

3.7

62.5

51.3

63.4

63.9

64.9

55.1

130

9.3

117

119

67.6

These data are shown in table 7. Vapor phase concentrations for over half of the reported values are larger 

than the maximum atmospheric concentration, indicating the widespread presence of CFCs from nonatmospheric sources in the ground water. In one well, 

FTC-1-24, CFC concentrations were small, much less 

than the maximum concentrations, possibly indicating 

ground water older than 50 years. However, this well 

is also anoxic and recent studies have shown that CFCs 

can be microbially degraded under reducing conditions 

such as those present in this well. A subsequent 

sample from FTC-1 -24 was analyzed for tritium, which 

produced a concentration of 26 tritium units indicating 

that the ground-water age was young, less than 50 years

and confirming that the low concentrations of CFCs in 

this well were likely due to microbial degradation of 

the CFCs. Thus, the use of CFC concentrations for 

age-dating ground-water samples in the transboundary 

region of the Abbotsford-Sumas aquifer is unreliable.

SUMMARY

Ground-water quality and hydrogeologic data 

were collected from nine wells in the transboundary 

region of the Abbotsford-Sumas aquifer. Water-quality 

data included the concentrations of selected common 

ions, trace elements, pesticides, and volatile organic

22
compounds, including three chlorofluorocarbons used 

to estimate residence times of ground water. The concentrations of common ions and trace elements were 

generally small resulting in low total dissolved constituents. However, the concentrations of nitrate were 

generally large: seven of nine wells yield water having 

concentrations of nitrate greater than both Canadian 

and United States drinking water guidelines and 

standards. Nitrate was the only water-quality constituent detected in these samples at concentrations above 

the Canadian and United States drinking water guidelines or standards. Twenty-seven organic compounds 

were detected in the ground-water samples with concentrations ranging from 0.01 to 23 Jig/L. Four of these 

compounds are thought to be affected by sampling or 

analytical bias. Three chlorofluorocarbons, CFC-11, 

CFC-12, and CFC-113, were detected, typically at 

concentrations greater than the maximum atmospheric 

concentrations, indicating additional sources of CFCs 

other than atmospheric equilibration and that CFCs 

would not be a reliable ground-water age-dating tool 

for this aquifer.

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24 p.

Zaugg, S.D., Sandstrom, M.W, Smith, S.G., and Fehlberg, 

K.M., 1995, Methods of analysis by U.S. Geological 

Survey National Water Quality Laboratory determination of pesticides in water by C-18 solid-phase extraction and capillary-column gas chromatography/mass 

spectrometry with selected ion monitoring: U.S. 

Geological Survey Open-File Report 95-181, 49 p.

24
APPENDIX
Appendix A. Logs of lithologic description obtained during drilling of observation-monitoring piezometers, 

in the Abbotsford-Sumas Aquifer, British Columbia 

[--, no data]

Depth interval below land surface

Lithological description

Piezometer: 91-13; completed May 1991

Top soil and few gravel

Sand and gravel

Sandy gravel

Sand and gravel

Brown sand

Sandy gravel

Sand and gravel

Clay

Number 10 slot screen

Piezometer: 91-15; completed May 1991

Top soil and few gravel

Sand and gravel

Sandy gravel

Brown sand

Number 10 slot screen

Piezometer: FTC-1-24; completed October 1991

Gravel, cobble, and sand

Sand with clay, brown

Sand, medium to coarse, with gravel; greyish brown

Sand, medium to coarse with fine gravel; grey

Number 10 slot screen

Piezometer: ABB2; completed March 1988

Sand and fine to medium gravel

Sand and coarse gravel

Grey sand and cobbles (2.5 centimeters diameter)

Grey sand; fine to medium gravel

Grey sand; coarse gravel

Sand less silt; cobbles

Number 10 slot screen

(meters)

0.0-

0.9-

4.6-

8.2-

9.4-

11.9-

14.3-

20.4-

18.6-

0.0-

0.9-

4.6-

9.4-

8.2-

0.0-

0.3-

2.4-

3.7-

6.4-

0.0-

1.8-

2.9-

3.7-

5.8-

7.0-

6.6-

0.9

8.2

8.2

9.4

11.9

14.3

20.4

29.0

20.1

0.9

4.6

9.4

11.9

9.8

0.3

2.4

3.7

11.0

7.3

1.8

2.9

3.6

5.8

7.0

7.6

7.6

(feet)

0.0-

3.0-

15.0-

27.0-

31.0-

39.0-

47.0-

66.9-

61.0-

0.0-

3.0-

15.0-

31.0-

27.0-

0.0-

4.0-

8.0-

12.0-

20.9-

0.0-

6.0-

9.5-

12.0-

19.0-

23.0-

21.7-

3.0

15.0

27.0

31.0

39.0

47.0

66.9

95.0

66.0

3.0

15.0

31.0

39.0

32.0

4.0

8.0

12.0

36.0

24.0

6.0

9.5

12.0

19.0

23.0

25.0

25.0

26
Appendix A. Logs of lithologic description obtained during drilling of observation-monitoring piezometers, 

in the Abbotsford-Sumas Aquifer, British Columbia-Continued

Depth interval below land surface

Lithological description

Piezometer: ABB4; completed March 1988

Sand and coarse gravel, oxidized

Grey sand and very coarse gravel

Grey sand; fine to coarse gravel

Sand; very fine gravel

Sand; coarse gravel

Silty sand and fine gravel

Silty sand and very fine gravel

Grey sand and coarse gravel

Grey sand; very fine gravel

Grey sand; fine to coarse gravel

Sand and gravel; cobbles

Sand and very fine gravel to coarse gravel

Sand and coarse gravel

Sand and gravel; some cobbles

Number 10 slot screen

Piezometer: ABBS; completed March 1988

Clayey sand and gravel; oxidized

Silty brown sand; slight clay

Grey sand and coarse gravel

Grey sand and fine gravel; cobbles

Grey sand and pea gravel

Sand and coarser gravel; cobbles

Grey sand and gravel; no pebbles

Number 10 slot screen

Piezometer: BCME-B-20; complete 1988

Top soil

Sand and gravel with lenses of sand

Number 10 slot screen

Piezometer: 94 LEH; completed 1994

Top soil

Sand and gravel

Number 10 slot screen

(meters)

0.0- 0.9

0.9- 6.9

6.9-11.0

11.0- 14.5

14.5 - 14.6

14.6-17.2

17.2- 17.4

17.4- 19.4

19.4-20.3

20.3 - 24.5

24.5 - 24.8

24.8 - 26.2

26.2 - 28.5

28.5 - 29.3

28.3 - 29.3

0.0 - 3.7

3.7-5.3

5.3 - 6.4

6.4 - 7.6

7.6-7.9

7.9-8.5

8.5-8.8

7.8-8.8

0.0- 0.6

0.6- 10.7

3.0- 5.5

0.0- 0.3

0.3 - 22.9

8.2- 9.8

(feet)

0.0- 3.0

3.0-22.5

22.5 - 36.0

36.0 - 47.5

47.5 - 48.0

48.0 - 56.5

56.5 - 57.0

57.0 - 63.5

63.5 - 67.0

67.0 - 80.5

80.5-81.5

81.5-86.0

86.0 - 93.5

93.5 - 96.0

92.7 - 96.0

0.0- 12.0

12.0- 17.5

17.5-21.0

21.0-25.0

25.0 - 26.0

26.0 - 28.0

28.0 - 29.0

25.7 - 29.0

0.0- 2.0

2.0-35.0

10.0-18

0.0- 4.0

4.0-75'

27.0 - 32.0

27
Appendix A. Logs of lithologic description obtained during drilling of observation-monitoring piezometers, 

in the Abbotsford-Sumas Aquifer, British Columbia-Continued

Depth interval below land surface

Lithological description (meters) (feet)

Piezometer: 94-SR-29; completed 1994

Brown sandy clay

Brown sand and gravel

Grey sand with clay lenses

Silty sand and gravel

Brown clay and sand

Sandy brown clay with pebbles

Sandy grey clay with pebbles

Sand and gravel

Dirty coarse sand with clay lenses

Number 10 slot screen

0.0- 2.7

2.7- 3.7

3.7- 5:5

5.5- 6.1

6.1-14.9

14.9 - 22.9

22.9 - 24.7

24.7 - 29.0

29.0 - 29.6

0.0- 9.0 

9.0- 12.0 

12.0- 18.0 

18.0-20.0 

20.0 - 49.0 

49.0 - 75.0 

75.0-81.0 

81.0-95.0 

95.0-97.0

28

 ft- U.S. GOVERNMENT PRINTING OFFICE: 2000 589-121 / 03006 Region No. 10