Ground-Water Sampling Methods and Quality-Control 

Data for the Red River of the North Basin, Minnesota, 

North Dakota, and South Dakota, 1993-95

By Michael A. Menheer and Mark E. Brigham________________

U.S. Geological Survey

Water-Resources Investigations Report 96-4317

Contribution from the National 

Water-Quality Assessment Program

Mounds View, Minnesota 

1997
U.S. DEPARTMENT OF THE INTERIOR

BRUCE BABBITT, Secretary

U.S. GEOLOGICAL SURVEY

Gordon P. Eaton, Director

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

District Chief U.S. Geological Survey

U.S. Geological Survey Branch of Information Services

2280 Woodale Drive Box 25286

Mounds View, MN 55112 Denver, Colorado 80225-0286

Information regarding the National Water-Quality Assessment (NAWQA) Program is 

available on the Internet via the World Wide Web. You may connect to the Red River of 

the North NAWQA Home Page using the Universal Resource Locator (URL) at:

<URL:http: / / wwwmn.cr. usgs.gov/redn/index.html>

tl
Foreword

The mission of the U.S. Geological Survey (USGS) is 

to assess the quantity and quality of the earth resources 

of the Nation and to provide information that will assist 

resource managers and policymakers at Federal, State, 

and local levels in making sound decisions. Assessment 

of water-quality conditions and trends is an important 

part of this overall mission.

One of the greatest challenges faced by waterresources scientists is acquiring reliable information that 

will guide the use and protection of the Nation's water 

resources. That challenge is being addressed by 

Federal, State, interstate, and local water-resource 

agencies and by many academic institutions. These 

organizations are collecting water-quality data for a host 

of purposes that include: compliance with permits and 

water-supply standards; development of remediation 

plans for specific contamination problems; operational 

decisions on industrial, wastewater, or water-supply 

facilities; and research on factors that affect water 

quality. An additional need for water-quality 

information is to provide a basis on which regional- and 

national-level policy decisions can be based. Wise 

decisions must be based on sound information. As a 

society we need to know whether certain types of waterquality problems are isolated or ubiquitous, whether 

there are significant differences in conditions among 

regions, whether the conditions are changing over time, 

and why these conditions change from place to place 

and over time. The information can be used to help 

determine the efficacy of existing water-quality policies 

and to help analysts determine the need for and likely 

consequences of new policies.

To address these needs, the U.S. Congress 

appropriated funds in 1986 for the USGS to begin a 

pilot program in seven project areas to develop and 

refine the National Water-Quality Assessment 

(NAWQA) Program. In 1991, the USGS began full 

implementation of the program. The NAWQA Program 

builds upon an existing base of water-quality studies of 

the USGS, as well as those of other Federal, State, and 

local agencies. The objectives of the NAWQA Program 

are to:

 Describe current water-quality conditions for a 

large part of the Nation's freshwater streams, 

rivers, and aquifers.

 Describe how water quality is changing over time.

 Improve understanding of the primary natural and 

human factors that affect water-quality 

conditions.

This information will help support the development 

and evaluation of management, regulatory, and

monitoring decisions by other Federal, State, and local 

agencies to protect, use, and enhance water resource?

The goals of the NAWQA Program are being 

achieved through ongoing and proposed investigations 

of 60 of the Nation's most important river basins and 

aquifer systems, which are referred to as study units. 

These study units are distributed throughout the Nation 

and cover a diversity of hydrogeologic settings. More 

than two-thirds of the Nation's freshwater use occur? 

within the 60 study units and more than two-thirds of 

the people served by public water-supply systems live 

within their boundaries.

National synthesis of data analysis, based on 

aggregation of comparable information obtained from 

the study units, is a major component of the prograrr 

This effort focuses on selected water-quality topics 

using nationally consistent information. Comparative 

studies will explain differences and similarities in 

observed water-quality conditions among study areas 

and will identify changes and trends and their cause?. 

The first topics addressed by the national synthesis are 

pesticides, nutrients, volatile organic compounds, and 

aquatic biology. Discussions on these and other waterquality topics will be published in periodic summaries 

of the quality of the Nation's ground and surface water 

as the information becomes available.

This report is an element of the comprehensive body 

of information developed as part of the NAWQA 

Program. The program depends heavily on the advice, 

cooperation, and information from many Federal, State, 

interstate, Tribal, and local agencies and the public. The 

assistance and suggestions of all are greatly appreciated.

Robert M. Hirsch 

Chief Hydrologist
Contents

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

Introduction...................................................... 1

Purpose and scope............................................................................................................................................ 1

Acknowledgments...............................................................................................^ 1

Well description and development......................................................................................................................... 2

Sampling methods.................................................................................................................................................. 3

Sample collection and processing.................................................................................................................... 3

Sample filters and bottles................................................................................................................................. 16

Field trip preparation........................................................................................................................................ 16

Sampling equipment decontamination................................................................................................................... 17

Quality control....................................................................................................................................................... 18

Replicates......................................................................................................................................................... 19

Blariks.........................................................^ 19

Ground-water matrix spikes............................................................................................................................. 20

Suirogates......................................................................................................................................................^ 20

Summary of quality-control data ........................................................................................................................... 20

Schedule 1369 radon..................................................................................................................................... 20

Schedule 1810 radium-226 and uranium....................................................................................................... 21

Schedule 1043/2703 trace elements.............................................................................................................. 21

Schedule 2750 major ions and silica............................................................................................................. 21

Schedule 2752 nutrients................................................................................................................................ 24

Schedule 2001 pesticides............................................................................................................................... 24

Schedule 2050 pesticides............................................................................................................................... 24

Schedule 2085 dissolved organic carbon ...................................................................................................... 29

Schedule 2090 volatile organic compounds.................................................................................................. 29

References cited..................................................................................................................................................... 30

Supplemental Information...................................................................................................................................... 32

Sample collection equipment........................................................................................................................... 33

Decontamination supplies................................................................................................................................ 34

Sample shipping and other supplies................................................................................................................. 34

Illustrations

Figure 1. Map showing location of Red River of the North Basin study unit and

ground-water sampling sites............................................................................................................. 2

2. Observation well construction .......................................................................................................... 4

3a. Schematic of ground-water sampling equipment............................................................................. 5

v
Illustrations continued

3b. Photograph of ground-water sampling equipment............................................................................ 6

4. Photograph of interior of vehicle with ground-water sampling equipment...................................... 7

5. Ground-water quality field notes form.............................................................................................. 9-12

6. Photograph of radon-sampling assembly.......................................................................................... 15

Tables

Table 1. Ground-water-quality sample collection order and protocol............................................................ 13

2. Quality-control blank-sample collection order and protocol............................................................ 14

3. Summary of quality-control data for trace elements......................................................................... 22

4. Summary of quality-control data for major ions and silica.............................................................. 23

5. Summary of quality-control data for nutrients.................................................................................. 25

6. Summary of spike-recovery data for schedule 2001 pesticides........................................................ 26

7. Summary of surrogate-recovery data for schedule 2001 pesticides in water.................................... 27

8. Summary of spike-recovery data for schedule 2050 pesticides........................................................ 28

Conversion Factors, Abbreviations, Acronyms, and Definitions

Multiply By To obtain

foot (ft) 0.3048 meter

gallon (gal) 3.785 liter

gallon per minute (gal/min) .06308 liter per second

degree Fahrenheit (°F) (°F - 32)/l .8 degree Celsius

Chemical concentrations: Chemical concentrations of substances in water are given in metric units of 

micrograms per liter (jlg/L). Micrograms per liter is a unit expressing the concentration of chemical 

constituents in solution as mass (micrograms) of solute per unit volume (liter) of water. One thousand 

micrograms per liter is equivalent to one milligram per liter.

Use of trade names in this report is for identification purposes only and does not constitute endorsement 

by the U.S. Geological Survey.

VI
Abbreviations, Acronyms, and Definitions:

CV coefficient of variation, the standard deviation divided by mean, multiplied by 100 to express in

percent.

DI deionized water.

DO dissolved oxygen.

DOC dissolved organic carbon.

HC1 hydrochloric acid.

HPLC high performance liquid chromatography

MDL method detection limit, the smallest concentration of an analyte which can be accurately detected

and quantified by an analytical method.

|ig/L microgram per liter, concentration of an analyte expressed in 1 x 10"6 grams per liter.

Jim micrometer or micron, filter pore size expressed in 1 x 10"6 meter.

|iS/cm microsiemens per centimeter, the specific electrical conductance of water, equivalent to

micromhos per centimeter at 25 degrees Celsius.

mg/L milligram per liter, concentration of an analyte expressed in 1 x 10"3 grams per liter.

MRL minimum reporting level, the smallest concentration, for a given analyte and method, that is

reported by a laboratory.

NAWQA National Water Quality Assessment Program.

NWQL National Water Quality Laboratory, a laboratory operated by the U.S. Geological Survey in

Arvada, Colorado.

OWQ Office of Water Quality.

QC quality control.

QWSU Water Quality Service Unit, U.S. Geological Survey.

SD standard deviation.

USGS U.S. Geological Survey.

VOC volatile organic compounds.

Vll
Ground-Water Sampling Methods and Quality-Control

Data for the Red River of the North Basin, Minnesota,

North Dakota, and South Dakota, 1993-95

By Michael A. Menheer and Mark E. Brigham

Abstract

Ground-water-quality samples were collected for the intensive data-collection phase of the Red River of the P Torth 

Basin study unit, one of 60 study units of the National Water Quality Assessment (NAWQA) Program throughout the 

United States. The sampling protocols used were designed for the NAWQA Program. The protocols include 

sampling equipment, cleaning procedures, sample-collection methods, and quality-control plans to monitor the 

accuracy of the data collected. One of the goals of the NAWQA Program was to collect data using similar methcds to 

build a nationally consistent water-quality data base.

Quality-control data demonstrated that most constituents measured for this study yielded reproducible data, with 

low to undetectable contamination from the sampling and analytical procedures. Several constituents were 

occasionally or frequently detected in blank samples at levels similar to low-concentration ground-water-quality 

samples. For example, iron was detected in 75 percent of the blank samples, with a maximum concentration of 27 

[ig/L, indicating that iron contamination may interfere with its determination at low levels in ground waters. Copper, 

aluminum, and dissolved organic carbon concentrations in blank samples overlap those determined in ground-waterquality samples, thereby precluding quantitative reporting of those constituents. Most pesticide data are reproducible, 

with minimal bias. Some pesticides had low but consistent recoveries; these data may be useful if spike and surrogate 

data are carefully considered. Data for some pesticides measured in this study should not be quantitatively reported 

or used, because they may underestimate the concentrations of those pesticides in ground waters.

Introduction

The USGS began full implementation of the 

NAWQA Program in 1991. The goal of this program is 

to collect reliable and nationally consistent information 

on the status of and trends in the quality of the Nation's 

water resources, and to provide scientifically valid 

explanations of these conditions and trends (Cohen and 

others, 1988, p. 1147). Much of the data collected will 

come from 60 hydrologic regions called study units. 

The part of the Red River of the North drainage basin in 

the United States (hereinafter referred to as the Red 

River Basin) is one of these 60 study units. An intensive 

ground-water data collection phase for the Red River 

Basin study unit began in 1993 and continued through 

1995. Figure 1 shows the location of the study unit and 

of the wells sampled. Data from the study units will be 

compiled in a national data base. National synthesis 

teams will review and make larger-scale assessments 

and interpretations of the data.

Purpose and Scope

The purpose of this report is to describe the groundwater sampling protocols, sampling equipment, field 

data-collection techniques, and quality-control data used 

during the intensive data-collection phase of the Red 

River Basin NAWQA study. This report describes (1) 

methods used to prepare wells for sampling, (2) 

equipment used, (3) sample collection procedures, (4) 

shipping and storage of the samples, (5) equipment 

cleaning procedures, (6) and types of quality-control 

samples collected, with a summary of the qualitycontrol data.

Acknowledgments

Special appreciation is given to the numerous 

property owners in the Red River Basin study unit for 

allowing observation wells to be installed on their 

property or water-quality samples to be collected from 

their wells, and to Tim Cowdery, U.S. Geological 

Survey, for his guidance in the collection of the fieH 

samples.
100' MANITOBA

49°

Ground-water wells 

A Surficial-aquifer well 

_ Buried-aquifer well

LOCATION MAP

V^_x0

0

SCALE

50 10

i i

! I

50 100 KILOMETERS

101 MILES

Figure 1. Location of Red River of the North Basin study unit 

and ground-water sampling sites.

Well Description and Development

Ground-water sampling for the NAWQA Program 

was designed to investigate study areas at several 

different spatial scales. A large-scale study-unit survey 

was done to provide an overview of the water quality. 

Wells included in this study were selected from preexisting wells screened in surficial and buried aquifers. 

Pre-existing wells were privately owned domestic wells, 

farm wells used for livestock and irrigation, and smallbusiness wells.

On a more geographically limited scale, a land-use 

study was done to consider the effects of human 

activities on the quality of the ground water. Wells 

selected included pre-existing, privately owned wells 

and observation wells drilled for this study.

The pre-existing wells were chosen from wells which 

met the following criteria:

(1) The depth and type of well screen, or open 

interval, was known.
(2) The casing material and well diameter were 

known.

(3) The stratigraphy of the bore hole, usually 

recorded on a well log, was known to determine if the 

well was screened in a surficial or buried aquifer.

(4) The water, at the sampling point, was untreated.

A small-scale study was done to monitor changes in 

water quality along defined flowpaths to determine landuse effects (Stoner and Lorenz, 1995). Two flowpaths 

through surficial aquifers (located in the land-use study 

area) were investigated. All wells for the flowpath study 

were drilled by study-unit personnel.

Seventy-five wells were drilled for this study using a 

hollow-stem rotary hydraulic auger drill rig. Drill 

cuttings from the bore holes were described and 

collected for archival. Cores were collected in 

polycarbonate tubing at several sites. The drilling 

equipment was cleaned between each site using a steam 

cleaner or a commercial self-car-wash facility to 

minimize the possibility of cross contamination between 

well sites. Observation-well construction for this study 

is shown schematically in figure 2. The well casing 

used was flush-threaded 2-inch inside-diameter (ID), 

poly vinyl chloride (PVC). Two types of screens were 

used. The majority were 5-ft-long, flush-threaded, 

machine-slotted (0.010 slot), PVC screens. Sandpacked PVC screens were used for nine wells finished in 

silty-sand aquifers. Washed medium to coarse sand was 

used to backfill the hole around the well screen. 

Bentonite grout was pumped into the annular space 

above the sand pack. A 6.5-inch ID diameter, 7-ft-long 

protective steel casing was placed around the PVC 

casing at the land surface to protect the well. This 

protection pipe was cemented in place to divert surface 

drainage away from the well. An aluminum locking cap 

was installed on the top of the pipe.

Wells installed for this study were developed. Well 

development refers to any of several techniques used to 

remove particles and sediment from the bottom of the 

well, the well screen, and the formation immediately 

surrounding the well screen. Wells were developed to 

remove excess fine-grained particles from the screen 

and well for the following reasons:

(1) Analytes could adsorb to sediment in the water, 

making it difficult to obtain a sample that is 

representative of the ground water;

(2) Particles could fully or partially clog the well 

screen, preventing a good hydraulic connection between 

the well and the surrounding formation. (This is

important because it allows the water in the surrounding 

formation to enter the well from the whole or most of 

the screened interval, not a restricted area); and

(3) Fine-grained particles will wear out sampling 

pumps and clog filters used to collect samples.

The wells were developed by pumping with a hand 

pump and/or a gas powered centrifugal pump. When the 

water being pumped from the well began to clear, some 

native water was poured back into the well. This was 

done to suspend particles in the water so they could be 

pumped from the well. A hand pump was often used to 

begin pumping the well. A hand pump was used 

because it would pump sediment-laden water without 

clogging or being damaged. The hand pump was used 

until the water visibly began to clear or the well was 

pumped dry.

If the well pumped dry it was allowed to refill with 

water and was pumped again. While pumping, native 

water from the well was collected in a bucket and was 

poured back into the well. This was done to reduce the 

time needed for the well to recharge with water. If the 

water level was less than 25 ft below land surface, and 

the well produced enough water, a motorized centrifugal 

pump was used to pump the well for a longer period of 

time, 0.5-1.5 hours. During pumping, a visual 

description of the water clarity, flow rate, and volume of 

water pumped was recorded. Flow rate was measured 

using a graduated water bucket and a stop watch. Waterlevels were measured before and after the well was 

pumped to determine water-level recovery. Water-level 

recovery was an indicator of production-zone 

permeability and an adequately developed well. It was 

necessary to redevelop some wells that had not been 

pumped for 8 to 12 months before samples were 

collected.

Sampling Methods

The sampling equipment (fig. 3a and 3b) and 

procedures used in the Red River Basin study were 

based on the ground-water sampling protocols of the 

NAWQA Program (Lapham and others, 1995; and 

Koterba and others, 1995). A list of the equipment used 

for sampling is contained in the Supplemental 

Information section at the end of this report.

Sample Collection and Processing

The sampling equipment was designed to minimize 

contact between atmospheric, ambient conditions, and 

the sample water. The samples were collected in one of 

two vehicles equipped specifically for this study (fig. 4). 

One vehicle was used only occasionally for flowpath-
Aluminim locking cap

Padlock

Water table

7 ft x 6.5 in. ID protective 

steel casing

Neat cement

Land surface

2 in. ID PVC well casing

Grout 

(bentonite)

Sand pack

Well screen

Well cap

Figure 2. Observation well construction.
Unfiltered line Pressure tubing

Land 

surface

Water 

table\

Submersible 

pump --''

Teflon tubing

Flow manifold

Variable, threeway flow valve

Filtered line 

Capsule filter

_ Well Quick connect 

fittings

Quick connect fittings

Nalgene tubing

Sample

collectionchamber

pH probe 

-Waste line

Specific conductivity 

probe

Well screen

Temperature probe

Dissolved oxygen 

probe

Flow-through 

cell

Waste line

Waste line

Gas filter/ desiccant

Nitrogen 

gas tank

Figure 3a. Schematic of ground-water sampling equipment.
Teflon 

standpipe

Sampling 

pump

Flow-through cell 

with probes

Stainless steel 

pesticide 

filter unit

Sample collection 

chamber frame

Figure 3b. Photograph of ground-water sampling equipment.

study sampling, for analysis of nutrients, major ions, 

dissolved organic carbon, tritium, and stable isotopes 

(deuterium and oxygen-18).

The submersible-sampling pumps used were, Keck 

model SP-87, Grundfos Redi-Flow II pumps, or the 

pump present in privately owned pre-existing wells. 

The Keck pump was used for most of the 1993-95 

intensive-sampling period. The Keck and Grundfos 

Redi-Flow II pumps were equipped with a variable flow 

rate control. The Keck pump was powered by a deepcycle marine battery. The Grundfos pump was powered 

by a 120/240 volt 20 ampere gas-powered generator. 

The generator was transported in a trailer and was 

operated 30 to 40 feet downwind of the sampling site to 

avoid contamination from the exhaust.

Privately owned wells were sampled from an outside 

tap to ensure that the water did not pass through a water 

softener, or other water-treatment procedures. If a

sample was collected after a pressure tank, the pressuretank volume was included in the volume of water to be 

purged before sampling the well. A disposable, plastic 

threaded adapter was used to connect the tap to the 

Teflon tubing that was connected to the flow manifold.

Prior to sampling a well, a static water level was 

measured, if possible. In some wells, it was not possible 

to measure water levels because of submersible pumps 

in the well casing. The water level reported by the 

driller on the well log was recorded. Then aluminum 

foil or the plastic bag covering the pump was removed 

and the pump was lowered into the well 1 to 2 ft below 

the water level. The tubing from the pump was 

connected to the flow manifold and the flow of water 

was directed through the flow manifold to a waste line. 

A stop watch and a graduated bucket were used to 

determine the flow rate. The volume of water in the well 

was determined, based on the water-level measurement,
Capsule filter 

Flow manifold

Sampling 

pump

Field parameter 

meters

Flow-through cell 

with probes

Sample collection 

chamber

Figure 4. Photograph of interior of vehicle with ground-water sampling equipment.

the well diameter, and the depth of the well. The time 

needed to purge three well volumes of water was 

calculated using the flow rate and the volume of water in 

the well. A standard field form (fig. 5) was used to 

record the field data.

Initially the pump was set to a high flow rate to 

quickly purge the well. The flow rate was reduced after 

the calculated purge volume had been pumped prior to 

field parameter measurements. The field parameter 

measurements included air and water temperature, pH, 

specific conductance, DO, alkalinity, and barometric 

pressure.

A Hydrolab Scout II fitted with a flow-through cell 

was used to measure the field parameters during the 

1993 field season. A Geotech flow-through cell with an 

Orion model 250A pH meter, equipped with either a 

silver/silver chloride (Ag/AgCl) electrode or a Ross

combination electrode; an Orion model 124 

conductivity meter; and a dissolved oxygen meter were 

used during the 1994 and 1995 field seasons. The 

temperature probe on the pH meter was used to measure 

the water temperature.

The meters were calibrated with fresh conductivity 

standards and pH buffers daily before sampling and the 

calibrations were checked at the end of each day. The 

calibrations were recorded in a log book kept for each 

meter and on the field form for the first site sampled 

each day. Field parameter meters and standards were 

not stored in the sampling vehicles when not on a 

sampling trip, because excessive heat or cold could 

damage the meters or affect the values of the standards.

When monitoring field parameters, the flow rate was 

adjusted to 1 gal/min to reduce turbidity, and flow was 

diverted from the waste line to the flow-through cell.
Water entered the flow-through cell at the bottom and 

flowed out at the top. The flow-through cell was made 

of clear polycarbonate plastic for visual inspection of 

the probes during sampling. Field parameter readings 

were recorded every several minutes. The water level 

and flow rate were recorded with each set of readings. 

When three consecutive readings met the following 

criteria the well was considered purged and the water 

representative of the aquifer. The field parameter 

criteria were:

for pH, readings within 0.1 standard unit 

for specific if conductance was less than 100 

conductance, (iS/cm, readings within 5 }J,S/cm; if 

100-1,000 }iS/cm, readings within 10 

(iS/cm; if greater than 1,000 (iS/cm, 

readings within 50 

readings within 0.3 mg/L

readings within 0.2°C

for dissolved 

oxygen, 

for water 

temperature,

The flow rate was adjusted to 0.4-0.6 gal/min before 

beginning to collect samples. The well was pumped at 

this rate until all of the samples had been collected and a 

final set of field parameters had been recorded.

The DO meter was considered accurate to 0.2 mg/L. 

In cases where this low concentration was reached, the 

water was checked for a hydrogen sulfide gas (rotten 

egg) smell. If hydrogen sulfide was detected, the DO 

probe was removed from the flow-through cell to 

prevent fouling.

Sample water with 0.2 mg/L or less DO was 

considered anoxic and the samples were collected using 

the following reduced-oxygen sampling-environment 

protocols. Nitrogen gas was used to displace the oxygen 

in the sample bottle, which could chemically alter the 

low-oxygen sample water. The nitrogen gas was passed 

through drierite (calcium sulfate), a desiccant, to remove 

any moisture from the gas, then through corrugated 

Teflon tubing into the sample collection chamber. The 

uncapped sample bottles were held inverted, the tubing 

was placed into the bottle near the bottom, and the 

nitrogen gas was pumped into the bottles for 10-20 

seconds. The bottle was considered to be filled with 

nitrogen gas. The inverted bottle was quickly capped. 

The samples were collected while the bottle was held 

under a rigid polycarbonate bell with nitrogen gas 

continuously pumped into the bell to displace any air.

The sample collection order, analytical laboratory 

schedules, and related information for the ground-waterquality samples are summarized in table 1. Note that for 

some schedules more than one bottle is collected. QC 

replicate and triplicate samples were collected in the 

same order. QC blank sample order is summarized in 

table 2. The capsule filter was changed between 

collection of ground-water-quality and QC samples.

Most samples were collected in a sample-collection 

chamber, which was covered with a clear plastic bag. 

The sample-collection chamber and the samplepreservation chambers were frames made out of 0.5 inch 

ID PVC pipes and elbows fastened with nylon screws. 

Powder-free latex gloves were worn while sampling. 

Additional information on NAWQA sample collection 

protocols, are described in Koterba and others (1995).

Sample collection protocols for VOC, radon, tritium 

3 18 16 (H ), and stable isotopes (Oxygen /Oxygen and

deuterium/protium, H /H ) are briefly discussed below 

because of their special collection requirements.

The VOC sample was collected first to avoid 

overpurging the well and thereby collecting a 

nonrepresentative sample. The VOC sample was 

collected unfiltered and in triplicate.

A 40-mL clear glass sample vial was held with the 

Teflon tubing near the bottom of the vial. The vial was 

not rinsed. The vial was slowly lowered as it filled with 

sample water. Care was taken to avoid creating air 

bubbles while collecting the sample as aeration of the 

water can affect the VOC concentration, due to 

volatilization. The vial was allowed to overfill creating 

an inverted meniscus at the top of the vial. The vial was 

capped, inverted, and tapped to check for air bubbles. If 

any air bubbles were found, the vial was discarded and a 

new sample was collected. The VOC samples were 

chilled with ice.

The radon sample was collected outside of the sample 

collection chamber from a special assembly using a 

syringe (fig. 6). The assembly was fitted with a flow 

valve used to constrict the flow of water against a 

septum through which a needle was inserted to collect 

the sample. The septum on the radon assembly was held 

so that it pointed downward to prevent any air bubbles 

from accumulating. The flow valve was partially closed 

so pressure was exerted on the septum. The syringe was 

inserted into the septum. The valve on the radon 

assembly was closed further until the syringe could be 

filled with sample water with minimal effort. A 

minimum of 20 mL of sample water was used to rinse 

the syringe. Another 20 mL of water was collected. The 

syringe was withdrawn from the septum, held vertically, 

and 5 mL of sample water was forced out to
Proj. Name, No.

Loc. Well No. 5F?5

Site I.D.

U.S. GEOLOGICAL SURVEY, WRD, GROUND-WATER QUAUTY FIELD NOTES

NAWQA, 4627127O4 Date 9-7-95 Time O9:OO

BOA-1 3/92

(3rd printing.

1st ad.)

4 6 3 O 5 O O 9 7 2 1 3 4 O 1

Composite Samples? I I 

BYES.tndtaate:

Dates__________

YES ED NO

Sampled by M Menheer, P iareon, K £?ay/<?r__________ 

Record No. 995OO342 Sample Purpose (71999):

Times

SMS Cntrl. No.

15.OO

Altitude, ft (72000)

Depth top sample 

interval (72015)

Depth bottom sample 

interval (72016)

Allowable drawdown (ft.)

995

9.5

18 7O

WELL DATA

Static water level, 

ft (72019)

Dia. inside (in.) 

Screened/ 

open interval Top:

[3 Well

1462 *

Open Hole CH Spring

ZOO

93O

Casing vol. (gal.) 

Purge vol. (gal.) 

Bottom:

O.65

195

1&7O

Casing Vol. (gal.) - 0.0408 X Ola (In.) X Height (ft) 

Height« H - Well Depth - Static Water Level -

OR Cas. Vol. - H X F

F - Casing volume factor

Location 135N53W16&&PBBAO1

SAMPLING DATA

____ Date well last sampled &-22-95

Minutes pumped before sampling (72004) 27 static water level when well last sampled 1423

Sampler type (841 64) 4O46 ___________

4010 - thief PUMPS: 4060 - gas reclp.

4020 - bailer 4030 - suction pump 4070 - gas Ntt

4025 - double-valve 4040 - submersible 4080 - peristaltic

bailer 4050 - squeeze 4090 - jet

4100 - flowing well 8010.0 - other

Sampler ID

Sampling condition (72006) ______ 

0.10 - site was being pumped 4. - flowing 

0.11 - site recently pumped * - pumping

30. - seeping

31. - nearby well 

pumping

VOLUME 

FACTORS

Cas. Vol. 

Dia Factor 

(in.) F

1.0

1.5

2.0

3.0

4.0

4.5

5.0

6.0

8.0

10.0

12.0

24.0

36.0

0.04

0.09

0.16

0.37

0.65

0.83

1.02

1.47

2.61

4.08

5.88

23.5

52.9

REPN KECK #123

Sampler material: [Stainless Steel [Brass PVC Teflon Other Viton

112 SNPL GW , , , Aquifer Name: _ Color light brown Clarity cloudy

Sample extracted and processed under [X] oxygenated I I nonoxygenated conditions

Sample contact with: DP atmosphere [ ] oxygen [ | nitrogen I 1 other

Weather: Clear [Partly Cloudy I Cloudy Light Medium Heavy Snow Rain Calm Light 

Breeze I Very Gusty Windy Very Cold 'Warm Hot Other

FIELD MEASUREMENTS

Q.6

9.3 

&

7.34

Q. Inst. (00059)

Temp. Water (00010)

Temp. Air (00020)

pH (00400)

Sp. Cond. (00095)

Dis. Oxy. (00300)

DO Sat. (00301)

Bar. Press. (00025)

Remarks WL = 16.72 - 2.1O = 14.62

951

GPM Eh (00090)

C Alkalinity ( 39O&6 ) 

C Bicarbonate ( OO453 ) 

units Carbonate ( OO452 ) -

)-

484

591

0.5

7A&

j/S/cm25C Hydroxide ( 

E. Coli(31633) 

FC (31625) 

FS(31673)

mm H9 Other:

. m volts

mg/L

mg/L 

mg/L 

mg/L

mg/L 

%

-col./100mL;Rmk

-col./100mL;Rmk

-col./100 mL; Rmk

SAMPLES COLLECTED

Nutrients DTl TOC I I 

Major Ions [3 DOC EQ 

SOCO Filt. _____ mL 

BODED ______ O

CODE: ___ o

ORGANICS TR. ELEMENTS 

Unfillered CD 

Filtered O

Pesticide 

VOC

BNA

isotope rn

Tritium [Tl

LABORATORY SCHEDULES

Lab Schedules Req. (or copy o1 

lab request form attached | |)

Lab Codes Add (A) Delete (D):

pH meter £> used for titration

Checked by Date

Figure 5. Ground-water quality field notes form.
TEMPERATURE

Lab Thermometer I I Checked w/ASTM within + 0.5 C; Date 

Down-Hole Sensor | | Describe

AMPULE LOT NUMBERS:

255s NA-4364-IGSI

nitric add/potassium dtahromate

pH A - O04O27 

Mtr W-no. B - OO2688 METER Make/Model Orion / 25OA

A

electrode no.

pH Buffer

7.0

7.O

4.0

pH Butter 

_ o.^ T«mp C

15.0

15.4

Initial Reading

7.O1

1O.11

7.O2

3.97

electrode type

Adj. Reading

7.03

1O.11

7.03

4.00

millivolts (redox meas) Remarks

Slope = 10O.6

Slope = 1OO.5

ry-i unfiltered i i filtered 

l^-l sample ' ' sample

Temp correction factors for 

buffers applied? El YES Q] NO

stirrer used? C] YES E] 

if yes,

D magnetic i i manually 

stirrer I J stirred

NO

ri 9UU9GU i ipio i fviii wi pi i [ 

measurement location: Churn | flow through chamber single point at depth vertical avg of

Sample Temp = 9.3 C 7.37

SPECIFIC CONDUCTANCE

Mtr W-no. O9O5123 METER Make/Model Orion/124

7.34 7.34 lll^

probe no.

standard value

495

744

1OOO

T*mp 

8W °C

13.9

13.8

14.O

Initial Reading

508

764

1020

Adj. Reading Remarks

correction factor applied?

[X]YES | | NO 

I X| auto temp compensated meter

I | manual temp compensated metei 

corr. factor = __

SC subsample from or SC Churn | flow through chamber] single point at 

measurement location:

depth vertical avg of

952 952 951

DISSOLVED OXYGEN W-no. _ 2295638 METER Make/Model Orion/82O

D.O. measurement location 

or D.O. subsample from : Churn

Calibration: BOD bottle D.O. Zero Check 

\Y] Air Calibration in Water | | Air Calibration Chamber in Air (using zero D.O. solution)

flow through chamber single point at depth vertical avg of ___ points 

YES DD NO

Thermistor Check | | YES NO

| | Air-Saturation Deionized Water | | Calibration by WinklerTrtratton 

Slope = -1.O6 (attach Supplementary Winkler page) 

BAR. PRESS ________ mm Hg; 

(mm = in. X 25.4)~~~~ ^"^ Corr' Factor H^D Temp. __________ °C

Chart D.O. Sat. mg/L stirrerused? EH YES Q NO if yes, Q magnetic stirrer j I manually stirred

Meter D.O. Sat. mg/L; Adjusted to

(if corr. factor applicable)

GROUND WATEfl D.O, * 0.5

QUALITY ASSURANCE SAMPLES

Were quality assurance samples collected? 

O YES [T] NO If YES indicate type(s):

Organicfree Dl

water from 

sampling site

Replicate | | [ [

Spike O d I I

. . . , Supplementary

Field Blank I I LJ page w/addltional

Other | | Indicate Type(s):

Calibration Notes and Remarks

Figure 5. Ground-water quality field notes form - continued.

10
Temp 

1O.1

11.9

ALKALINITY

PH

7.37

6.88

6.55

6.25

5.77

5.36

5.19

5.16

5.11

5.O8

5.O3

4.97

4.9O

4.82

472

4.61

4.47

4.31

4.14

4.O2

3.90

3.80

A pH

Initial

O.49

O.33

0.30

0.48

O.41

O.17

O.O3

O.O5

O.O3

O.05

O.O6

O.O7

O.O8

O.1O

0.11

O.14

0.16

O.17

O.12

O.12

O.1O

Vol acid 

DC or mL

1OO

2OO

3OO

40O

45O

46O

462

464

466

468

47O

472

474

476

4.78

48O

482

484

486

488

49O

AVol acid 

DCormL

10O

1OO

100

100

5O

1O

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

Acid: 1 1. 60 N] 0.1 600 N 0.01639N OTHER 

Acid Lot No. : 4/l2&

Samp

| A |

Sample s

pH: Star

DC (Digh 

Vol. titrat

>ie Volume 

Filtered 

jtirred: [X

t 737

: 100 mL

I | Unfiltered 

] magnet caily | | r

End 5.80

A pH

A Vol acid

O.OO49

O.OO33

O.OOO3

O.OO48

O.OO82

O.O17

O.O15

O.O25

O.O15

O.O25

O.O5

O.O55

O.O4

O.O5

O.O55

O.O7

0.08

O.085

O.O6

O.O6

O.O5

nanually

al Counts) or 

ed at End Point near pH 8.3 :

Digital Counts or 

Vol. titrated at End Point near pH 4.5 : ^84

r-y-i Incremental i i Fixed i i Gran 

LLJ Equivalence I I End Point I I Ttaratlon

Date 9-7-95 Time O9:25

CALCULATIONS : 

F 1 * (0

CO = Ax xCF CC 

3 mL sample 2 

0 

-i F 2 * u_

urv^ r D O/A\ i u 

3 mL sample F..

F2

ALKALINITY p * p 

asCaCO - Bx xOF 3

3 mL sample

A = DC or ml_s acid from initial ^ 

pH to endpoint near 8.3 = " Q

»- 

B = DC or mLs acid from initial Q

pH to endpoint near 4.5 = 484 u-

* 1

APPLY CORRECTION FACTOR (CF) IF ACID USED FOR F

BURETTE TfTRATION HAS NONSTANDARO NORMAUTYCF - corr. factor - H 2SO4 normaHly/0.01639 3

(IMPORTANT : CF NOT APPLICABLE FOR THE DiGfTAl 

SHOWN; use only with nonstandard normality BURETTE

ALKALINITY ( 59O86) 484 mo/L as CaCO

BICARBONATE ( 00455) 591 mg/L as HCC7'

CARBONATE ( OO452 ) - mo/Las CO 3

DIGITAL CCUNT 

TITRATION (DC)

Using Using 

0.1600 1.60 

normal normal

12.0

12.2

10.0

120

122

100

BURETTE * 

TITRATION (mL)

Using mi of 

0.0 1639 normal

983.5

1000

820.2

. TfTRATiON 

: t'rtration)

N( 

3 ATTACH C 

IF ALKALI 

ARE CALC 

ACOMPU

FACTORS

OTE: 

>UTP'fTCOP 

MITY VALUES 

JULATEO US) 

TEH PROOFW

Y

NO 

kM

OBSERVATIONS/CALCULATIONS :

Figure 5. Ground-water quality field notes form -- continued.

11
Time

O8-.51

O9:OO

O9:O6

O9-.1O

O9-.14

O9:18

O9-.19

O9:23

O9.24

09:25

O9:3O

Water 

Level Ww

Miscellaneous Section (Notes/Calculatlons/Well Purge Log & Etc.)

WELL PURGE LOG 

Draw Wel Yield 

Down WhenSampNng Q 

feet gpm ds pH T C SC DO 

72040 00059 00400 00010 00095 00300

Pump on

16.86

16.87

16.92

16.87

16.88

2.24 O.6

2.25 O.6

2.3O O.65

2.25 O.6

2.26 0.6

-water silty to sandy

-flow turne. d to flow ce I

7.26 9.8 945 O.9

7.31 9.3 952 O.5

7.34 9.3 952 O.5

7.34 9.3 951 O.5

Sample be.yan

Sample end

16.89 2.27 7.33 9.4 949 O.5

Pump off

16.72 2.1O

\r 

fi 

k

E

Tirr 

Timejn 

@35C:

Time in @ 

Time out :

Vol. 

(mL)

Blank

Blank

* Remarks

E. COU (31633) 

e collected :

44.5°C :

Date:

Date:

Used in * 

Count calculation? Remarks

1 - Less than 2 

0 - Est ct. K

- Greater than 

-non ideal ct

icub. Time 2 hrs @ 35 C followed by : 

It. size 20-24 hrs @ 44.5°C

leal count 20-80 col. 

.COLI COUNT /100mL ; Rmk

FECAL STREPTOCOCCI (31673)

Time collected :

Time in : 

Timeout

vol.

(mL)

Blank

Blank

'Remarks

Date:

Date:

Used* * 

Count calculation? Remarks

1 - Less than 2 - Greater than 

0 - Eat ct K » non Ideal ct

Incub. Time 46-50 hrs tilt, size

Ideal count 20-1 00 col. Incub. Temp 35 C 

FS COUNT/ 100 mL ; Rmk

FECAL COLIFORM (31625 

Time collected :

Time in : Date :

Time out : Date :

VoL Usedln * 

(mL) Count caJcutatton? Remarks

Blank

Blank

* Remarks 1 " Less tfwi 2 " Greater then 

0-Estct K- non Weal ct

Incub. Time 22-26 hrs filt. size

0

Ideal count 20-60 col. Incub. Temp 44.5 C 

FC COUNT/ 100 mL ; Rmk

CALCULATIONS

Figure 5. Ground-water quality field notes form - continued.

12
Table 1 . Ground-water-quality sample collection order and protocol

[mL, milliliter; C-18 SPE, carbon-18 solid phase extraction analytical method; |im, micrometer; PE, polyethylene bottle; HNO3, nitric acid; N/A, not applicable; 

Memo., technical memorandum]

Schedule Schedule name Reference Filter type Bottle size/type Fill method 

No air space 

Leave air space 

Leave air space 

Leave air space 

Leave air space 

Leave air space 

Leave air space 

Leave air space 

No air space 

Leave air space 

Leave air space 

Leave air space 

No air space 

No air space

Pre

2090 Volatile organic compounds

2001 Pesticides (C-18 SPE)

2050 Pesticides (activated carbon)

2085 Dissolved organic carbon

2703 Trace elements

2750 Major ions

2752 Nutrients

1810 Radioactive elements

N/A Field alkalinity

2703 Trace elements

2750 Major ions and silica

1369 Radon

1565 Tritium

1142 Stable isotopes

1 None

2 Glass fiber (0.7 (im)

3 Glass fiber (0.7 (im)

4 Silver (0.45 (im)

4. 5 Capsule (0.45 (im)

5 Capsule (0.45 [im)

5. 6 Capsule (0.45 \ua)

4, 7 Capsule (0.45 (im)

8 Capsule (0.45 [im)

4,5 None

5 None

4 None

7 None

7 None

40 mL x 3/clear glass

1 liter/amber glass

1 liter/amber glass

250 mL/amber glass

500 mL/acid-rinsed PE

250 mL x 2/acid-rinsed PE

125 mL/brownPE

1 liter X 2/acid-rinsed PE

250 mL/PE

250 mL/PE

250 mL/PE

10 mL x 2/clear glass

1 liter/PE

60 mL/clear glass

Chil

Chil

Chil

Chil

1 mL 

lmL

Chil

2 mL 

Chil

Non

Non

Min

Non

Non

1 Rose and Schroeder, 1995.

2 Zaugg and others, 1995.

3 Werner and others, 1996. 

Selected constituents(s) listed in Timme, 1995, method not yet published.

5 Fishman and Friedman, 1989, U.S. Geological Survey OWQ Tech. Memo. 94.09.

6 Patton and Truitt, 1992, U.S. Geological Survey OWQ Tech. Memo. 94.16.

7 Thatcher and others, 1977.

8 Koterba and others, 1995.
Table 2. Quality-control blank-sample collection order and protocol

[mL, milliliter; C-18 SPE, carbon-18 solid phase extraction analytical method; |lm, micrometer; PE, polyethylene bottle; HNO3, nit

Schedule

2090

2001

2050

2085

2750

2752

1810

2750

2750

Schedule name

Volatile organic compounds

Pesticides (C-18 SPE)

Pesticides (Activated carbon)

Dissolved organic carbon

Major ions

Nutrients

Radioactive elements

Major ions

Major ions

Filter type

None

Glass fiber (0.7 |im)

Glass fiber (0.7 |im)

Silver (0.45 Jim)

Capsule (0.45 |im)

Capsule (0.45 |im)

Capsule (0.45 |im)

Capsule (0.45 fim)

None

Bottle size/type

40mL x 3/clear glass

1 liter/amber glass

1 liter/amber glass

1 25 mL/amber glass

250 mL/amber glass

125 mL/brownPE

1 liter x 2/acid-rinsed PE

500 mL/PE

250 mL/PE

Fill method

No air space

Leave air space

Leave air space

Leave air space

Leave air space

Leave air space

Leave air space

Leave air space

Leave air space

Prese

Chill

Chill

Chill

Chill

1 mL H

Chill

2mLHN

Chill

None
Quick-conn 

in-flow fitting

Figure 6. Photograph of radon-sampling assembly.

remove any air that may have been collected in the 

syringe. Two vials half filled with mineral oil were used 

to collect the sample. With the tip of the syringe in the 

mineral oil, near the bottom of the sample vial, 10 mL of 

water was slowly dispensed. Five mL of water was left 

in the syringe to assure the accuracy of the volume 

dispensed. The entire procedure was repeated with a 

second vial. The two vials were shaken for 30 seconds 

and shipped the same day to the laboratory.

The tritium and stable isotope samples were both 

collected without rinsing the bottles. Also, both of the 

bottles were filled to overflowing and conical caps were 

used to avoid air bubbles in the sample.

All samples requiring chemical preservation were 

treated shortly after they were collected. Gloves were 

changed before beginning to use each type of 

preservative, and a separate preservation chamber was 

used for each type of preservative. All sample bottles 

were opened in the preservation chamber, treated, and 

immediately recapped. The samples that needed to be 

chilled were immediately placed in coolers filled with 

ice.

When the last sample had been collected, the flow of 

water was diverted to the flow-through cell. A final set 

of field parameters were recorded. The pump and the 

sampling equipment were cleaned using the field

decontamination protocols, as described later in this 

report, and the alkalinity samples were titrated as 

described by Koterba and others (1995, p. 62).

Alkalinity was determined on site by incremental 

equivalence titration, within several hours after the 

sample was collected. A Hach digital titrator, 1.6 

normality (sulfuric acid titrant), 100 mL of sample 

water, an Orion 250A pH meter, a Teflon-coated 

magnetic spinbar, and a battery-powered magnetic 

stirrer were used (Koterba and others, 1995, p. 62-70).

During 1994, two alkalinity samples were titrated at 

each site; a filtered (0.45 micrometer filter) and an 

unfiltered sample. Alkalinity values for 123 pairs of 

titrations were determined, representing a wide range 

(45-742 mg/L as calcium carbonate). The data from 

these two methods were very similar, with no detectable 

method bias. The lack of bias was confirmed 

statistically by a paired t-test. Differences in alkalinity 

between paired samples appeared to be within the 

precision of the method. The relative percent difference 

(100 x [unfiltered alkalinity - filtered alkalinity] / 

[unfiltered alkalinity + filtered alkalinity]) between 

unfiltered and filtered alkalinity ranged from -4.64 to 

4.23 percent, with a mean of-0.047 percent. The 

number of filtered and unfiltered alkalinity data sets 

with a relative percent difference (absolute value) of less

15
than 1.99 was 110. Therefore, beginning in November 

1994, only filtered samples were titrated for alkalinity.

The samples were sent to the NWQL for analysis. 

The chilled samples were shipped in a cooler, with ice, 

daily from the field by a next-day delivery service. 

Samples with longer holding times were shipped at the 

end of the week (U.S. Geological Survey, Technical 

Memorandum 92.06, 1992). The tritium sample, stable 

isotope sample, and a duplicate major ions sample were 

archived in the Mounds View, Minnesota office of the 

USGS for possible analysis at a later date. A list of the 

supplies used to ship samples is listed in the 

Supplemental Information section at the end of this 

report.

Sample Filters and Bottles

Several types of filters were used to process groundwater samples. DOC samples were collected using an 

Osmonics, Inc., 0.45 Jim pore size, 47 mm diameter, 

silver filter held in a Gelman Sciences pressure barrel 

filtration unit.

A stainless steel filter unit was used to collect all of 

the filtered samples, except DOC, during the 1993 field 

season. A 0.7 Jim pore size, 142 mm diameter, prebaked, glass-fiber filter held on a stainless steel filtration 

unit was used to filter the pesticide samples. A 0.45 Jim, 

142 mm diameter cellulose nitrate filter was used on the 

same filtration unit to collect the rest of the filtered 

samples.

The stainless steel filter unit was used only for 

pesticide sampling following the 1993 field season. The 

reasons for this were:

(1) The physical size of the stainless steel filter unit 

was large, making it difficult to use in the sample 

collection chamber.

(2) The filter unit had several parts with grooves and 

threads, which made it difficult to clean thoroughly.

(3) The filter unit was made of stainless steel, which 

became worn with continued use and cleaning. This 

made sealing the filter to avoid leaks increasingly 

difficult and could possibly allow unfiltered water to be 

collected along with the sample. Also, these worn areas 

were places contaminants could accumulate.

(4) This type of filter was prone to clogging (loading) 

due to sediment in the water, which led to a timeconsuming process of changing the filter.

(5) The filter could not be used to filter trace-element 

samples because of possible contamination from the 

metal filter unit.

These problems were eliminated by the use of 

capsule filters (Horowitz and others, 1994). Disposable 

0.45 Jim Gelman capsule filters were used during the 

1994 and 1995 field seasons.

Capsule filters and sample bottles were rinsed with 

DI water prior to sampling trips. The procedure for this 

rinsing, or pre-conditioning, is as follows:

(1) gloves were worn during the pre-conditioning;

(2) the capsule filters were rinsed with 1 liter of DI 

water;

(3) the filter was held so that the rinse water entered 

the filter at the bottom and flowed out at the top to 

ensure that the whole capsule filter was filled and rinsed;

(4) following this rinse, excess DI water was removed 

by shaking the filter;

(5) the filter was double bagged with plastic bags and 

chilled on ice or in a refrigerator until use; and

(6) pre-conditioned filters were used within 5 to 8 

days.

Sample bottles were rinsed three times with DI water, 

filled half full with DI water, and recapped. The DI 

water was poured out in the sample-collection chamber 

just prior to the field rinse with sample water and the 

collection of the sample.

Field Trip Preparation

The following checklist outlines the preparation done 

before leaving for a field trip. Several of the items were 

done only when required, not before every field trip.

(1) Perform routine maintenance on the meters.

(2) Charge or replace batteries.

(3) Clean the sampling equipment.

(4) Collect QC blank samples.

(5) Fill water containers.

(6) Pre-condition filters and bottles.

(7) Fill coolers with ice.

(8) Assemble well data, maps, and field plans for field 

trip.

16
(9) Contact well owners.

(10) Restock vehicle with equipment and supplies.

Sampling Equipment Decontamination

Sampling equipment was cleaned weekly in the 

Mounds View, Minnesota office of the USGS before 

each sampling trip and between each sampling site in 

the field, to minimize the possibility of sample 

contamination by the equipment. QC samples were 

collected routinely to assess potential contamination by 

equipment or sampling procedures. A complete list of 

supplies used in the decontamination process is listed in 

the Supplemental Information section at the end of this 

report.

Office decontamination of sampling equipment 

(tubing, flow-manifold, pesticide filter, DOC filter, 

sample chambers, graduated cylinders, and beakers) 

included the following steps:

(1) Clean washbasins with a Liquinox-tap water 

solution, then rinse with tap water.

(2) Disassemble and soak equipment in a 2 percent 

Liquinox-tap water solution for 30 minutes.

(3) Put on powderless latex gloves.

(4) Wash all of the equipment with sponges and nonmetallic brushes.

(5) Change gloves.

(6) Rinse all of the equipment with tap water.

(7) If sampling for trace elements, rinse all nonmetallic equipment with 5 percent HC1.

(8) Change gloves.

(9) Rinse all of the equipment with DI water.

(10) If sampling for pesticides, rinse the pesticide 

plate filter unit and forceps with methanol, let air dry, 

reassemble plate filter and wrap in aluminum foil.

(11) Wrap clean equipment with aluminum foil or 

plastic, if sampling for trace elements.

Cleaning the pump and pump tubing involved two 

people using a "clean hands", "dirty hands" method. 

One person wore gloves, handled the pump and the 

tubing, and was considered the "clean hands" person. 

This person avoided touching anything except the pump 

or the tubing. The "dirty hands" person assisted by 

turning the pump on or off, and refilling the standpipe

with water as necessary (Horowitz and others, 1994, p. 

8-9).

Office decontamination of the sampling pump 

included the following steps:

(1) Place the pump in the standpipe and coil puim 

tubing into a clean washbasin.

(2) Fill the standpipe and washbasin with a 2 percent 

Liquinox tap-water solution.

(3) Soak pump and tubing for 30 minutes.

(4) Put on gloves.

(5) Wash the external surface of the pump tubing with 

a sponge or a non-metallic brush.

(6) Pump Liquinox tap-water solution through the 

pump tubing at least 5 times. This water may be 

recirculated after some water has been pumped 

completely through the line.

(7) When an adequate volume of water has been 

pumped (5 to 7 gallons), let the pump run until the water 

has been removed from the pump tubing.

(8) Change gloves.

(9) Lift the pump out of the standpipe and the tubing 

out of the washbasin.

(10) Rinse the exterior of the pump and pump tub;ng 

with tap water. Place the tubing in a clean rinsed basin.

(11) Pour out the water remaining in the standpipe 

and rinse it with tap water.

(12) Place the pump back in the standpipe and fill it 

with tap water.

(13) Pump tap water through the tubing until the 

Liquinox tap-water solution is removed. Do not 

recirculate the tap water.

(14) Repeat steps 8 through 13 using DI water instead 

of tap water

(15) If sampling for organics, repeat steps 8 through 

13 using methanol (the methanol may be recirculated). 

Then repeat steps 8 through 13 again using DI water 

instead of methanol.

(16) Recoil the pump tubing on its reel.

(17) Wrap the pump in aluminum foil or plastic, if 

sampling for trace elements, and cover the pump tub; ng 

reel with a plastic bag.

17
The Gelman barrel DOC filtration unit was initially 

cleaned in a Liquinox tap-water solution followed by a 

tap and DI water rinse. QC blank samples collected 

following this cleaning showed problems with 

contamination. The barrel filter was then cleaned by 

rinsing it with DI water and wiping it dry with 

powderless tissue paper. The Liquinox detergent was 

determined to be the cause of the contamination. The 

DOC QC blank values are discussed at greater length in 

the Quality Control section of this report.

The equipment was also cleaned in the field between 

sampling sites. The procedures were the same as the 

office cleaning with the following exceptions:

(1) The exterior of the tubing on the flow-manifold 

was not washed.

(2) The equipment, pump, and tubing were not 

soaked.

(3) The Liquinox tap-water solution was reduced to 

0.1 percent Liquinox.

(4) The acid, methanol, and second DI rinse were not 

done.

After the 1993 field season the sample-collection 

chambers were cleaned by rinsing with DI water and 

replacing the chamber bag. The sample-preservation 

chambers were cleaned and their chamber bags were 

replaced at the end of each week, not between each site.

Field decontamination of sampling equipment 

included the following steps:

(1) Place the sampling equipment in a clean 

washbasin.

(2) Fill the washbasin with a 0.1-0.5 percent Liquinox 

tap-water solution.

(3) Put on gloves.

(4) Wash all of the equipment with sponges and nonmetallic brushes.

(5) Change gloves.

(6) Rinse all of the equipment with tap water.

(7) Rinse all of the equipment with DI water.

(8) If sampling for pesticides rinse the pesticide plate 

filter unit and forceps with methanol, let air dry, 

reassemble plate filter and wrap in aluminum foil.

(9) If sampling for trace elements, place clean 

equipment in plastic bags.

(10) Place a clean bag on the sample collectior 

chamber between each site.

Field decontamination of the sampling pump 

included the following steps:

(1) Place the pump in the standpipe and coil the pump 

tubing into a clean washbasin.

(2) Fill the standpipe and washbasin with a 0.1 -0.5 

percent Liquinox tap-water solution.

(3) Put on gloves.

(4) Wash the external surface of the pump tubing with 

a sponge or a non-metallic brush.

(5) Pump Liquinox-tap water solution through the 

pump tubing at least 5 times; this water may be 

recirculated after some water has been pumped 

completely through the line.

(6) When an adequate volume of water has been 

pumped (5-7 gallons), let the pump run until the water 

has been removed from the pump tubing.

(7) Change gloves.

(8) Lift the pump out of the standpipe and the tubing 

out of the washbasin.

(9) Rinse the pump and pump tubing with tap water, 

place the tubing in a clean rinsed basin.

(10) Pour out the water remaining in the standpipe 

and rinse it with tap water.

(11) Place the pump back in the standpipe and fill it 

with tap water.

(12) Pump tap water through the tubing until the 

Liquinox tap-water solution is removed. Do not 

recirculate the tap water.

(13) Repeat steps 8 through 13 using DI water instead 

of tap water. The DI water may be recirculated after 

some water has been pumped completely through the 

line.

(14) Recoil the pump tubing on its reel.

(15) Wrap the pump in aluminum foil or plastic, if 

sampling for trace elements, and cover pump tubing reel 

with a plastic bag.

Quality Control

To assess the quality of analytical data from this 

study, QC samples were routinely collected and 

analyzed. These samples collected were in addition to

18
laboratory QC samples, which were routinely analyzed 

to calibrate analytical instruments, validate analytical 

data, and compare analyses with other laboratories 

(described, in part, by Friedman and Erdmann, 1982). 

Field QC samples from this study were used to assess 

the entire process of collecting, handling, shipping, 

preserving, and analyzing of samples; and the reporting 

of analytical results. Uncertainty and bias introduced in 

each of these steps provides information about the 

overall uncertainty and bias of reported data. This 

section defines the main types of QC samples used, and 

the following section summarizes QC data for the 

analytical schedules used in this study.

Replicates

Samples were (usually 2, or, less often, 3) collected 

sequentially so they would be expected to be nearly 

identical in composition. Data from the analysis of the 

replicate samples were used to assess variability of the 

overall sampling and analytical process.

The procedure for collecting a replicate sample was 

to fill a second (duplicate) and in some case a third 

(triplicate) bottle with sample water. Replicate 

sample(s) were collected immediately following the 

regular sample in the same sample collection order 

(table 1). The filter was changed before the collection of 

duplicate and again before collection of triplicate 

samples.

Data from replicate-sample analyses were reviewed 

by calculating a CV for each analyte, for each set of 

replicates. For each group of replicate samples, the CV 

was plotted against the mean. These plots were used to 

assess how CV's varied as a function of concentration.

For many analytes, CV's showed no relation to 

concentration. For these analytes, a single, pooled CV 

was calculated for summarizing data variability.

For some analytes the CV's of a replicate set were 

large and (or) highly variable at low concentrations, but 

relatively low and constant at higher concentrations. 

For these analytes, the replicate data were split into lowconcentration (mean was less than 5 or 10 times the 

MDL) and high-concentration (mean was greater than or 

equal to 5 or 10 times the MDL) groups. Separate 

pooled CV's were calculated for each group. Analytical 

data commonly are more variable, on a relative basis, at 

low concentrations (relative to the MDL).

A problem in summarizing variability of data from 

this study is that low-concentration data often were 

reported to only one significant figure. This causes 

highly variable CV's. For example, values of 0.14 and

0.16 would be rounded to 0.1 and 0.2, respectively, 

producing large relative differences (as indicated by a 

large CV), although the absolute difference in 

concentrations is fairly small. Conversely, 

concentrations rounded to the same value (such as 0.16 

and 0.24, both rounded to 0.2) yield an artificially low 

CV of zero.

Pooled CV's were calculated to summarize the 

variability of each analyte. CV's were squared for 

pooling, and a weighted mean (weighted to degrees of 

freedom of each set of replicates) was calculated, as 

recommended by Anderson (1987, p. 44-45). The 

pooled CV is the square root of the weighted mean of 

the squared CV's. Concentrations reported as less than 

the MDL were not included in this analysis. Cases in 

which one replicate group had an unusually high CV, at 

concentrations greater than 10 times the MDL, were 

treated as outliers and were omitted from the pooled CV 

calculation.

Blanks

Blank samples were collected using water that had 

undetectable concentrations of the analytes of interest. 

The blank water was processed through all sampling 

equipment, collected, and sent to the NWQL for 

analysis to determine if any step of the sample 

collection or analysis process contaminated the sarmles.

Two types of blank samples were collected. Office 

equipment blanks were collected in the USGS 

laboratory in Mounds View, Minnesota to check the 

sampling equipment for contamination under controlled, 

indoor conditions. Equipment blanks also were 

collected in the field, under ambient conditions that 

could include dust, aerial pesticide spraying, or other 

potential sources of sample contamination. Distilled 

"blank" water obtained from the QWSU in Ocala, 

Florida was used for blank samples for inorganic 

analyses. HPLC reagent-grade water (Baker Analyzed, 

J.T. Baker Co.) was used for blank samples for organic 

chemical analyses. Each lot of blank water used for this 

study was analyzed by the NWQL. An equipment frank 

was processed in the USGS laboratory in Mounds View, 

Minnesota, prior to each field season, so that the results 

could be reviewed prior to sampling each year. The 

sample collection order and the type of blank water used 

for this sampling is listed in table 2.

The following evaluations were made for each 

analyte in the blank samples:

(1) If an analyte was not detected or was always less 

than the concentrations in ground-water-quality

19
samples, contamination was presumed to be 

insignificant; and,

(2) If analyte concentrations in QC blank samples 

exceeded concentrations in any of the ground-waterquality samples, this was considered an indication of a 

potential contamination problem. Further examination 

was made to determine the extent of sample 

contamination. Occasional, low-level blank-sample 

contamination may be unavoidable for some 

constituents, and does not preclude usefulness of 

ground-water-quality data for those constituents. 

Frequent, high-concentration contamination 

(concentrations comparable to or greater than those in 

ground-water-quality samples) indicates a problem in 

the sample collection and analysis procedures, which 

may preclude usefulness of data for quantitative 

purposes.

Ground-Water Matrix Spikes

Ground-water matrix spikes are ground-water QC 

samples to which known amounts of target analytes 

have been added. Spiked samples were used to assess 

bias and precision of pesticide analyses (Schedules 2001 

and 2050). Low recoveries of spiked analytes could 

indicate degradation of analytes, analytical interference 

from the sample matrix, and (or) poor analytical 

recovery. The NWQL assesses the last of these 

separately with laboratory-control spike samples (Zaugg 

and others, 1995).

Replicate, field-collected pesticide samples were 

spiked with 100 microliters (|iL) of spike solution 

following collection. The NWQL verified analyte 

concentrations in spike solutions, which were about 1 

nanogram per (iL (ng/|iL) for schedule 2001 and 10 

ng/jiL for schedule 2050. The solution was added to 

the samples using a micropipet fitted with a single-use, 

disposable, glass capillary tip. Field spike samples, field 

spike replicates, and lab spike samples were collected, 

although the last two were not collected with every 

spike sample. The lab spike was a sample bottle, 

containing HPLC-grade water, which was taken into the 

field, opened and spiked, then shipped back to the lab.

Spike-recovery data for each pesticide were analyzed 

in several steps. First, if the pesticide was detected in a 

paired ground-water sample, the ground-water 

concentration was subtracted from the spiked-sample 

concentration. If QC replicate samples were collected, 

the mean concentration was used. Next, the 

concentration was converted to mass of recovered 

pesticide, divided by mass of added pesticide, and 

multiplied by 100. Spike-recovery calculations are

more accurate if the analyte is at low concentration (or 

less than MDL) in the ambient ground-water-quality 

sample. If the amount of analyte in the ambient groundwater-quality sample approaches or exceeds the amount 

added to QC spiked samples, the spike recovery tends to 

be masked by uncertainty (imprecision) in the data.

Surrogates

Surrogates are added to samples, in a known amount, 

to provide a means of assessing analytical recovery for 

each analysis. Surrogates are chemicals that should 

have similar properties to the analytes of interest. They 

should not interfere (or co-elute, as in chromatography) 

with quantitation of the analytes of interest. In tl is 

study, surrogates were used only for the pesticide 

analytical schedules. The surrogates are added to 

samples immediately prior to extraction, and in tMs 

study, all extractions of ground-water-quality and QC 

samples were performed at the NWQL.

Surrogate data are reported as percent recover' of 

added surrogate. Some researchers use surrogaterecovery data to adjust measured pesticide 

concentrations to account for low and(or) variable 

recovery of analytes (measured concentrations are 

divided by percent surrogate recovery). To assess the 

usefulness of surrogate data for correcting pestic: de 

concentrations from this study, linear regression? of 

spike-recovery versus surrogate-recovery data fo- the 

matrix-spike samples were examined. The results, not 

presented in detail herein, showed that surrogate 

recoveries could be used to adjust measured 

concentrations of some pesticides.

Summary of Quality-Control Data

This section summarizes ground-water QC dafa 

collected by the Red River Basin study unit in 1993-95 

by laboratory schedule. Timme (1995) documents 

constituents by schedule number, and gives information 

about sample bottles used, also see table 1 and table 2. 

Where available, references to analytical method? are 

given herein. The references for each of the methods are 

summarized in table 1. Pritt and Raese (1992) 

document quality-assurance/quality-control procedures.

Schedule 1369 Radon

Three sets of duplicate samples were collected. The 

pooled CV for these sample sets is 20 percent. No other 

QC sampling was done for radon.

20
Schedule 1810 Radium-226 and Uranium

Three sets of duplicates for radium and five sets for 

uranium had values greater than their respective MDL's. 

For radium, two sets of replicates were near the MDL; 

thus, the pooled CV of 17 percent is influenced by data 

from low-concentration analyses where data are 

rounded to one significant figure. Uranium results were 

reproducible, with a pooled CV of 2.1 percent. These 

constituents were not detected in blank samples, 

indicating there was no sample contamination.

Schedule 1043/2703 Trace Elements

Table 3 summarizes QC data for trace elements. 

Blank samples for trace elements are only summarized 

herein if the source of blank water was the QWSU in 

Ocala, Florida.

Replicate QC data are limited for trace elements. 

Most of the data was reported below MDL's. Several 

trace elements were infrequently detected in ground 

water therefore only one to four sets of duplicate 

measurements for each analyte was reported above the 

MDL. Arsenic, barium, cobalt, molybdenum, nickel, 

and aluminum occurred in reproducible quantities. 

Chromium, copper, and zinc had pooled CV's from 0-19 

percent at concentrations greater than five times the 

MDL, at lower concentrations the pooled CV's were 

substantially greater.

Trace elements in ground-water-quality samples had 

concentrations reported as less than the MDL. 

Therefore the presence of trace elements greater than 

the MDL in blank samples suggests a potential for 

contamination in low concentration trace element 

ground-water-quality samples. Several trace elements 

were not detected in any blank samples. Barium, 

chromium, and copper were occasionally detected. Zinc 

and aluminum occurred frequently in blank samples. In 

some samples, trace element concentrations in QC blank 

samples exceeded those in many ground-water-quality 

samples. Maximum aluminum and copper 

concentrations in QC blank samples exceeded those in 

ground-water-quality samples thereby precluding 

quantitative use of data for these elements. A possible 

source of contamination may be the metallic 

components of the sampling pumps which contain 

copper, zinc, chromium, and aluminum. Fine particles 

derived from aquifer sediments could become entrained 

in sampling equipment, and cause metal contamination, 

although the cleaning procedures have attempted to 

minimize this possibility.

Schedule 2750 Major Ions and Silica

QC data for major ions and silica are summarized in 

table 4. Manganese was determined by both the trace 

element and major ion schedules. If both major ions and 

trace elements were analyzed in a given sample, the 

manganese value from the trace element analysis w?s 

used.

Analyses of most major ions were quite reproducible, 

with pooled CV's of less than 5 percent. Pooled CV's 

for potassium, silica, and iron (greater than 10 times the 

MDL) were less than 10 percent. Fluoride, bromide, 

and low-level iron measurements were more variable.

Potassium and bromide were not detected in any 

blank samples. Sodium and chloride were infrequently 

detected, and always at concentrations lower than the 

minimum concentration detected in ground-waterquality samples. Fluoride was detected in only 2 of 31 

blank samples, each time at the MDL of 0.1 mg/L. 

Sulfate was infrequently detected in blank samples, at 

concentrations of 0.1 (the MDL) to 0.3 mg/L. Two 

ground-water-quality samples had similarly low sulfate 

concentrations (<0.1 mg/L); therefore the potential for 

sulfate contamination in the ground-water-quality 

samples was considered quite low. Silica was frequently 

detected in blank samples, but always at concentrations 

lower than in ground-water-quality samples.

Manganese was a low-level contaminant in 13 of 34 

blank samples, with a maximum concentration of 4.0 

|ig/L. Sixty-eight of 323 ground-water-quality samples 

had manganese concentrations less or equal to the 

highest blank sample concentration.

Iron contaminated three-fourths of the blank samp'es, 

with a maximum concentration of 27 (ig/L. Seventythree ground-water-quality samples had iron 

concentrations less than the MDL of 3.0 (ig/L; 134 had 

concentrations less than or equal to the highest blank 

sample iron concentration. Thus, iron contamination 

likely interferes with low-level iron determinations in 

ground-water-quality samples. A source of iron 

contamination may be steel components of the 

submersible sampling pump.

The blank-sample data indicate that the analytical 

methods are sufficient for higher levels of manganese 

and iron, and for distinguishing between high- and lowconcentrations. Contamination appears to be 

insignificant above about 5 (Ig/L for manganese, and 

about 30 |ig/L for iron.

21
to 

to

Table 3. Summary of quality-control data for trace elements

[MDL, maximum detection limit; N, number of samples; (ig/L, micrograms per liter; <, less than; , not detected; CV, coefficient of variation; Replicate data are s

exceed the MDL. For chromium, copper, and zinc, replicate sets were divided into high concentration (greater than times the MDL) and low co

Ambient ground water

Analyte

Aluminum

Antimony

Arsenic

Barium

Beryllium

Cadmium

Chromium

Cobalt

Copper

Lead

Molybdenum

Nickel

Selenium

Silver

Zinc

MDL

1.0

1.0

1.0

1.0

1.0

1.0

1.0

1.0

1.0

1.0

1.0

1.0

1.0

1.0

1.0

Minimum 

N (|ig/L)

29 <1.0

29 <1.0

55 <1.0

41 6.0

41 <.5

41 <1.0

41 <1.0

41 <1.0

41 <1.0

41 <1.0

41 <1.0

41 <1.0

39 <1.0

39 <1.0

41 <2.0

Concentration

10th Maximum 

percentile (|-ig/L)

<1.0 11

<1.0 <7.0

<1.0 49

10 520

<.5 <7

<1.0 1

<3.0 22

<1.0 8.0

<1.0 62

<1.0 10

<2.0 27

<1.0 23

<1.0 1.0

<1.0 1.0

3.0 1,000

Blanks

Concentration

Minimum Maximum 

N N>MDL (|ig/L) (Hg/L)

5 5 4.0 14

5 -- <1.0

7 -- <1.0

6 2 <1.0 19

6 -- <.5

6 -- <1.0

6 3 <1.0 9.0

6 -- <1.0

6 3 <1.0 101

6 - <1.0

6 - <1.0

6 <1.0

6 <1.0

6 -- <1.0

6 5 <3.0 20

Numb

N gro

6

--

6

8

--

--

8

2

6

--

4

2

-

8

6

2

3

-

3

4

-

-

4

3

-

2

-

-

4

3
Table 4. Summary of quality-control data for major ions and silica

[Concentrations in milligrams per liter, except iron, which is in micrograms per liter. MDL, method detection limit in milligrams per liter, except for iron and manga

N, number of samples; <, less than; , not detected; CV, coefficient of variation. Replicate data are summarized only where concentrations exceed the MDL. Chlo

one set of replicates with atypically bad reproducibility; these were treated as outliers and deleted from the summary. For iron, replicate sets were divided into high 

concentration ranges.]

Ambient ground water

Concentration

Analyte MDL N

10th 

Minimum percentile Maximum N N>MDL

Blanks

Concentration

90th 

Minimum percentile Maximum

Num

N gr

In milligrams per liter:

Calcium

Magnesium

Potassium

Sodium

Bromide

Chloride

Sulfate

Floride

Silica

0.02 323

.01 323

.1 323

.2 323

1.0 322

.1 329

.1 322

.1 322

.01 323

1.8

.57

<.l

1.0

<.01

.4

<.l

<.l

8.8

61

14

.6

1.9

.01

1.4

4.0

<.l

20

510

500

83

3,400

8.4

4,800

2,700

3.1

52

32

32

32

32

31

32

32

31

32

31

29

0

6

__

7

7

2

29

<0.02 1.2 3.5

<.01 .29 1.2

<.l

<.l .40 .9

<.01

<.l .20 .3

<.l .20 .3

<.l -- .1

<.01 .98 4.5

61

61

61

61

59

58

61

50

61

In micrograms per liter:

Iron

Manganese

3.0 323

40 18

11 5

1.0 323

<3.0

high

low

<1.0

<3.0

7.5

21

<1.0

9,700

1,500

32

34

24

13

<3.0 12 27

<1.0 -- 4.0

51

-
Schedule 2752 Nutrients

QC data for nutrient analyses are summarized in table 

5. Replicate nutrient analyses exhibited large ranges in 

CV's at low (near MDL) concentrations. These large 

ranges in CV's are partially a result of rounding to one 

significant figure at low concentrations, as discussed 

earlier. Absolute differences in concentrations were 

generally small. Nutrient analyses were more 

reproducible, as indicated by CV's, at concentrations 

greater than or equal to 10 times the MDL. Nitrite plus 

nitrate, and nitrite, which was infrequently detected, had 

pooled CV's of less than 10 percent. The other nutrients 

were split into low- and high-concentration groups (less 

than 10 times the MDL, and greater than or equal to 10 

times the MDL, respectively) for summary. Analyses of 

high-concentration samples were the most reproducible. 

Low-concentration replicates showed fairly large CV's, 

although absolute differences in concentration were fairly 

small.

In general, QC blank samples for nutrients had little or 

no detectable contamination. Ammonia plus organic 

nitrogen was not detected in any blank samples. Nitrite 

and orthophosphate were infrequently detected at the 

MDL. Nitrite plus nitrate and dissolved phosphorus were 

detected infrequently, and at concentrations near the 

MDL. Ammonia was detected frequently at levels 

ranging from 0.01 mg/L (the MDL) to 0.04 mg/L. This 

low level of contamination was observed by the NWQL 

in routine ammonia analyses. Therefore, low-level (less 

than about 0.05 mg/L) measurements of ammonia are 

subject to contamination.

Schedule 2001 Pesticides

Schedule 2001 pesticides, determined by the method 

of Zaugg and others (1995), were infrequently detected in 

ground water in this study. Replicate QC data are 

insufficient to characterize variability in these data; see 

the section on Ground-Water Matrix Spikes. Sixteen QC 

blank samples were collected. Atrazine was the only 

pesticide detected (in a single sample at a concentration 

of 0.012 jig/L). The ground-water-quality sample 

collected directly prior to the collection of this blank 

sample had no detectable atrazine; therefore, it is unlikely 

that the contamination of this blank was due to crosscontamination from sampling equipment.

QC spike data, summarized in table 6, were used to 

assess recovery of pesticides added to ground-waterquality samples. Most pesticides had mean recoveries 

between 75 and 110 percent. Exceptions are 

desethylatrazine, benfluralin, p,p '-DDE, malathion, 

methyl parathion, metribuzin, pendimethalin, cispermethrin, phorate, terbacil, and trifluralin.

The variability of pesticide data, indicated by the 

standard deviation and CV of spike-recovery data, varies 

among compounds. For many compounds, variability is 

relatively low (CV less than 20 percent). Highly variable 

recoveries (CV greater than 40 percent) were observed 

for terbacil, disulfoton, carbaryl, propargite, azinphosmethyl, and cw-permethrin. One spiked sample was 

omitted from the calculation of atrazine recovery because 

the paired ground-water-quality sample had a high 

atrazine concentration relative to the amount added to the 

spiked sample. Acetochlor was not analyzed during the 

early part of this study, and was spiked in only two 

samples.

In describing this method, Zaugg and others (1995) 

reported highly variable recoveries for carbofuran, 

carbaryl, terbacil, and azinphos-methyl. When detected, 

concentrations of these compounds are now reported as 

"estimated". Two of the compounds we found to have 

poor performance from the Red River Basin spike 

recovery data (propargite, high variability; and cispermethrin, low recovery and high variability), but were 

not noted as problematic by Zaugg and others (1995).

Three surrogates were added to every pesticide 

schedule 2001 sample as a means of assessing method 

performance for every analysis. Recovery statistics for 

these compounds, for 182 regular and replicate groundwater samples, are presented in table 7. Surrogate 

recoveries were typically good (close to 100 percent). 

Concentrations of pesticides in ground water were not 

corrected for surrogate recovery.

Schedule 2050 Pesticides

Schedule 2050 pesticides determined by the method of 

Werner and others (1996) were infrequently detected in 

ground water in this study. Reproducibility is assessed 

with spiked samples, discussed below. None of the 

analytes were detected in any of the 17 QC blanl samples 

collected for this schedule.

Not all schedule 2050 pesticides were in eacl spike 

solution used during this study. Thus, spike datr 

(summarized in table 8) are limited, especially for some 

analytes. Of the 31 compounds that were spiked in at 

least five samples, 17 had mean spike recoveries between 

60 and 105 percent. Recoveries of schedule 2050 

pesticides tended to be more variable than for schedule 

2001 analytes, and were occasionally very low including 

a few recoveries of zero percent. Of the 31 compounds 

considered, CV's ranged from 18 to 164 percent. CV's 

were less than 30 percent for only 9 of the 31 conpounds. 

CV's exceeded 50 percent for 10 of the 31 compounds, 

indicating highly variable recoveries.

24
Table 5. Summary of quality-control data for nutrients

[Concentrations in milligrams per liter. MDL, method detection limit; mg/L, milligrams per liter; N, number of samples; <, less than; --, not detected; C

Ambient ground water

Concentration (mg/L)

MDL 10th 

Analyte (mg/L) N Minimum Percentile Maximum

Ammonia, as 0.01 323 <0.01 <0.015 4.5

nitrogen

Nitrite, as nitrogen .01 323 <.010 <.010 1.1

Ammonia plus .2 312 <.200 <.200 4.7 

organic nitrogen

Nitrite plus nitrate, .05 323 <.05 <.05 76

Dissolved .01 312 <.01 <.01 .84

phosphorus

Orthophosphate, .01 323 <.01 <.010 .84 

as phosphorus

Blanks

Concentration (mg/L)

90th Nu

N N>MDL Minimum percentile Maximum N g

29 18 <0.01 0.03 0.04 43

22

21

29 1 <.01 -- .01 4

29 - <.2 -- - 30

2

28

29 5 <05 .13 .30 21

29 8 <.01 .01 .03 29

9

20

29 3 <.01 .01 .01 31

6

25
Table 6. Summary of spike-recovery data for schedule 2001 pesticides

[MDL, method detection limit; |ig/L, micrograms per liter; N, number of samples; CV, coefficient of variation, or standard deviation expressed as a 

percentage of the mean; mean and standard deviation are in units of percent recovery.]

Spike recovery

Analyte

Acetochlor

Alachlor

Atrazine

Desethylatrazine

Azinphos-methyl

Benfluralin

Butylate

Carbaryl

Carbofuran

Chlorpyrifos

Cyanazine

DCPA (dacthal)

p,p'-DDE

Diazinon

Dieldrin

Diethylanaline

Disulfoton

EPTC (eptam)

Ethalfluralin

Ethoprop

Ethyl parathion

Fonofos

a-HCH

Y-HCH (lindane)

Linuron

Malathion

Methyl parathion

Metolachlor

Metribuzin

Molinate

Napropamide

Pebulate

Pendimethalin

c/5-permethrin

Phorate

Prometon

Pronamide

Propachlor

Propanil

MDL

0.009

.009

.001

.002

.001

.002

.002

.003

.003

.004

.004

.002

.006

.002

.001

.003

.017

.002

.004

.003

.004

.003

.002

.004

.002

.005

.006

.002

.004

.004

.003

.006

.004

.005

.002

.018

.003

.007

.004

N

2

18

17

17

18

18

18

18

18

18

18

18

18

18

18

18

18

18

18

18

18

18

18

18

18

18

18

18

18

18

18

18

18

18

18

18

18

18

18

Mean 

(percent)

87

95

89

34

82

59

90

85

101

81

89

104

63

85

92

90

81

86

71

86

75

80

85

92

105

74

68

100

61

87

96

91

56

27

66

84

77

89

83

Standard 

deviation 

(percent)

1.1

15

13

9.2

72

15

5.4

41

37

15

23

18

7.8

16

14

8.3

52

11

21

15

14

10

14

15

37

25

16

19

14

12

16

15

17

17

20

15

15

10

18

CV

(percent)

1.3

16

15

27

88

25

6.0

48

37

19

26

17

12

19

15

9.2

64

13

30

17

19

13

17

16

35

34

24

19

23

14

17

16

30

63

30

18

19

11

22

26
Table 6. Summary of spike-recovery data for schedule 2001 pesticides continued

Spike recovery

Analyte

Propargite 

Simazine

Tebuthiuron

Terbacil

Terbufos

Thiobencarb

Triallate

Trifluralin

MDL 

Olg/L)

0.013 

.005

.010

.007

.013

.002

.001

.002

N

18 

18

18

18

18

18

18

18

Mean 

(percent)

110 

79

86

68

83

98

86

60

Standard 

deviation 

(percent)

97 

15

21

29

23

18

13

15

CV

(percent)

88 

19

24

43

27

18

15

25

Table 7. Summary of surrogate-recovery data for schedule 2001 pesticides in water

[J10, decadeuterated compound; d6, hexadeuterated compound]

Chemical name

Diazinon, dlQ 

Terbuthylazine 

Hexachlorocyclohexane, d6

Mean percent 

recovery

92.0 

96.8 

92.0

Standard 

deviation 

(percent)

20.4 

13.0 

18.2

Minimum 

(percent)

38.8 

60.3 

55.0

Maximum 

(percent)

149 

136 

170

Dicamba had good recoveries in 5 of 8 spiked samples 

(mean=82 percent), but low recoveries in 3 of 8 spiked 

samples (mean=10 percent). Oxamyl had consistent 

recoveries in 5 of 7 spiked samples (mean=21 percent), 

but very low recoveries in 2 of 7 spiked samples 

(mean=2.9 percent). Picloram had good recoveries in 3 

of 5 spiked samples (mean=69 percent), but recoveries 

of zero and 31 percent in the other 2 spiked samples. 

Bromoxynil, methomyl, and DNOC recoveries were 

good in 6 of 7 samples (mean=84, 64, and 67 percent, 

respectively); these compounds were not recovered in 

one spiked sample. Mean recovery of aldicarb in 6 of 9 

spiked samples was 54 percent, and was 15 percent in 3 

of 9 spiked samples. Mean recoveries of 2,4-DB in 7 of 

9 spiked samples was 52 percent, but in 2 of 9 spiked 

samples was 20 percent.

Analyzing a larger data set of laboratory-control 

spiked samples and field-submitted spiked samples, the 

NWQL found that recoveries usually were fairly good, 

but substantially more variable than for the schedule 

2001 method (Werner and others, 1996; U.S. Geological 

Survey, internal memorandum, NAWQA/NWQL 

Quality Assurance Committee for Schedule 2050/2051

Pesticide Method, Dec. 1, 1995). Method performance 

varied by analyte, and by time period for each analyte. 

During some time periods, recoveries of certain analytes 

were highly variable, including recoveries of zero 

percent for a small percentage of spiked samples. The 

NWQL considers analytical data for compounds that 

had low and(or) highly variable recoveries to be 

appropriate only for qualitative purposes. These 

compounds include 1-naphthol, chlorthalonil, 

dichlobenil, DNOC, and esfenvalerate. In addition, 

aldicarb sulfone, aldicarb sulfoxide, carbaryl, MCPB, 

methiocarb, and oxamyl had low and(or) highly variable 

recoveries in QC spiked samples from this study.

The main concern over low recoveries is that of lo^vbiased data, including false negatives (compounds that 

are in a sample at concentrations greater than the 

detection limit, but which fail to be detected because of 

analytical problems). Concentration ranges and 

frequencies of detection are potentially low-biased fcr 

such compounds, although the extent to which this is a

27
Table 8--Summary of spike-recovery data for schedule 2050 pesticides

[MDL, method detection limit; |lg/L, micrograms per liter; N, number of samples, CV, coefficient of variation, or standard deviation expressed as a

percentage of the mean; , not determined]

Spike recovery

Analyte

Acifluorfen

Aldicarb

Aldicarb sulfone

Aldicarb sulfoxide

Bentazon

Bromacil

Bromoxynil

Carbaryl

Carbofuran

3-hydroxycarbofuran

Chloramben

Chlorothalonil

Clopyralid

2,4-D

2,4-DB

Dacthl, mono-acid (DCPA)

Dicamba

Dichlobenil

Dichlorprop

Dinoseb

Diuron

DNOC

Esfenvalerate

Fenuron

Fluometuron

Linuron

MCPA

MCPB

Methiocarb

Methomyl

1-naphthol

Neburon

Norflurazon

Oryzalin

Oxamyl

Picloram

Propham

MDL

(|^g/L)

0.035

.016

.016

.021

.014

.035

.035

.008

.028

.014

.011

.035

.050

.035

.035

.017

.035

.020

.032

.035

.020

.035

.019

.013

.035

.018

.050

.035

.026

.017

.007

.015

.024

.019

.018

.050

.035

N

2

9

7

7

9

7

7

9

9

2

2

9

2

9

9

1

8

2

9

9

9

7

2

9

9

8

9

2

8

7

9

9

2

2

7

5

8

Mean 

(percent)

77

42

25

71

71

90

72

42

68

76

68

20

0

65

44

77

54

60

78

80

50

58

48

91

69

68

61

70

53

55

4.7

67

91

104

16

48

103

Standard 

deviation 

(percent)

4.5

23

30

39

28

20

34

31

23

28

8.7

30

0

17

21

--

41

8.6

21

25

21

29

5.7

34

14

18

11

7.7

37

26

6.9

20

9.3

9.3

11

32

28

CV

(percent)

5.8

55

120

55

39

22

47

74

34

37

13

150

--

26

48

--

76

14

27

31

42

50

12

37

20

26

18

11

70

47

146

30

10

8.9

69

67

27

28
Table 8--Summary of spike-recovery data for schedule 2050 pesticides continued

Spike recovery

Analyte

Propoxur 

Silvex 

2,4,5-T 

Triclopyr

MDL

Gig/L)

0.035 

.021 

.035 

.050

N

7 

9 

9

2

Mean 

(percent)

62 

70 

73 

39

Standard 

deviation 

(percent)

21 

16 

26 

4.0

CV

(percent)

34 

23 

36 

10

problem cannot be determined because "true" 

concentrations are unknown.

The problem of false negatives is likely to be more 

widespread than the opposite situation of false positives 

(where a detection is reported when the "true" 

concentration is less than the MDL). The NWQL is 

highly confident that when a compound is detected at 

concentrations greater than the detection limit, the 

compound has been properly identified and quantified.

Two surrogates were initially used for this method. 

Toluic acid was removed from the method because of 

poor recovery. The remaining surrogate, BDMC, had a 

mean recovery of 54 percent (range: 0-138 percent; 

standard deviation: 30 percent) in 170 samples from this 

study.

Schedule 2085 Dissolved Organic Carbon

DOC analyses were usually highly reproducible 

(pooled CV=5.5 percent). One set of replicates was 

omitted from the calculation because it was an outlier 

(variability in that set was much greater than the 

remaining sets of replicates).

All QC blank samples were contaminated with DOC. 

Although the range of DOC concentration in blank 

samples (0.1-63 mg/L) was similar to that of groundwater-quality samples (0.3-70 mg/L). Seventy-five 

percent of the DOC concentrations in blank samples 

were less than or equal to 0.8 mg/L; in contrast, 90 

percent of the ground-water-quality samples exceeded 

0.9 mg/L. Blank samples tended to have lower DOC 

concentrations. Thus, DOC sample contamination, 

presumably from sampling equipment, potentially 

interferes with its accurate determination at low levels in 

ground water (less than about 1 mg/L). While effective 

at minimizing cross contamination for many 

constituents (for example, pesticides and nutrients), the 

cleaning procedures, which use liquid detergent, may 

have contaminated the sampling equipment with DOC. 

Sampling equipment was initially cleaned daily in the

field with liquid detergent. All equipment was rinsed 

with DI water after cleaning. When contamination vas 

discovered, the DOC barrel filter was no longer washed 

with detergent. It was rinsed with DI water and wiped 

dry with powder-less laboratory tissues. This change in 

procedure did not yield noticeably lower DOC 

concentrations in blank samples. The contamination 

could have been coming from any of the sampling 

equipment, the pump, the manifold, or the tubing.

It is likely that DOC contamination from detergent is 

much greater in QC blank samples than in groundwater-quality samples. QC blank samples are collected 

immediately after cleaning the equipment, with only a 

small quantity of water being "wasted" prior to samole 

collection. In contrast, the large volume of ground 

water pumped through the sampling pump, tubing, and 

equipment while purging the well and monitoring fbld 

parameters before collecting the ground-water-quality 

DOC sample, provides a more effective rinse.

Schedule 2090 Volatile Organic Compounds

VOC samples (ground-water-quality and QC) were 

infrequently collected in this study. One QC blank 

sample was collected using organic-free blank wate~. 

Chloroform was the only analyte detected; its 

concentration was 0.4 |lg/L, which is twice the MDL.

One QC sample of DI water, from the USGS 

laboratory in Mounds View, Minnesota, was analyzed to 

determine possible VOC contaminants. This sample, 

contained the following VOC's (concentrations in 

|lg/L): dichlorobromomethane (1.0), 

chlorodibromomethane (0.7), chloroform (1.5), 1,2- 

dichloropropane (0.3), and toluene (0.3). The first three 

chemicals are trihalomethanes, or THM's, and are 

frequent contaminants in chlorinated municipal water 

supplies. 1,2-dichloropropane and toluene are common 

industrial solvents. Based on this sample, minimal o- no 

contamination of sampling equipment from DI water is 

expected for most analytes. All of the compounds

29
detected were less than 10 times the MDL of 0.2 (ig/L. 

Because the sampling equipment is thoroughly purged 

when sampling wells, such low-level contamination of 

DI water would probably not impart detectable 

quantities of VOC's to ground-water-quality samples.

To summarize, data from quality-control samples 

collected throughout this study show that for most 

constituents, the sampling and analytical procedures 

yield reproducible data. Bias from sample 

contamination is minimal or nonexistent for most 

constituents. Some constituents were detected in QC 

blank samples at low levels, comparable to lowconcentration ground-water-quality samples.

QC blank-sample data indicate problems for some 

constituents. Aluminum, copper, and DOC 

concentrations in QC blank samples overlapped with 

those in ambient samples. True concentrations of these 

constituents in ground water may be less (perhaps 

substantially less) than reported concentrations. The 

greater volume of water flowing through the sampling 

equipment likely minimizes DOC contamination in 

ground-water-quality samples compared to QC blank 

samples, which are collected directly after cleaning.

Systematic bias from poor analytical recovery is 

minimal for most pesticides. Schedule 2001 tends to be 

accurate and reproducible for most compounds; 

exceptions are carbofuran, carbaryl, terbacil, and 

azinphos-methyl (Zaugg and others, 1995). Variable 

propargite recoveries, and low, variable cis-permethrin 

recoveries in spiked samples from this study were 

observed.

Schedule 2050 typically yields lower, more variable 

analytical recoveries than schedule 2001. Occasionally 

and sporadically, very low (including zero percent) 

recoveries were observed in schedule 2050 analyses. 

Schedule 2050 data for pesticides in ground water are 

therefore possibly low-biased, and may include false 

negatives. The following pesticides were poorly 

quantified by schedule 2050, and are only appropriately 

analyzed for qualitative purposes: 1-naphthol, 

chlorthalonil, dichlobenil, DNOC, and esfenvalerate 

(Werner and others, 1996). In addition, aldicarb 

sulfone, aldicarb sulfoxide, carbaryl, MCPB, 

methiocarb, and oxamyl occasionally had low and(or) 

highly variable recoveries in spiked samples from this 

study.

References Cited

Anderson, R.L., 1987, Practical statistics for analytical 

chemists: Van Nostrand Reinhold, New York, 

p. 316.

Cohen, P., Alley, W.M., and Wilber, W.G., 198?, 

National water-quality assessment Future 

directions of the U.S. Geological Survey: Y rater 

Resources Bulletin, vol. 24, no. 6, p. 1147.

Fishman, M.J., and Friedman, L.C., 1989, Methods for 

determination of inorganic substances in We ter and 

fluvial sediments: U.S. Geological Survey 

Techniques of Water-Resources Investigations, 

book 5, chapter Al, 545 p.

Friedman, L.C., and Erdmann, D.E., 1982, Qual: ty

assurance practices for the chemical and biological 

analyses of water and fluvial sediments: U.S. 

Geological Survey Techniques of WaterResources Investigations, book 5, chapter A6, 

181 p.

Horowitz, A.J., Demas, C.R., Fitzgerald, K.K., Miller, 

T.L., and Rickert, D.A., 1994, U.S. Geological 

Survey protocol for the collection and processing 

of surface-water samples for the subsequert 

determination of inorganic constituents in filtered 

water: U.S. Geological Survey Open-File Report

94-539, 57 p.

Koterba, M.T., Wilde F.D., and Lapham, W.W., 1995, 

Ground-water data-collection protocols and 

procedures for the National Water-Quality 

Assessment Program Collection and 

documentation of water-quality samples and 

related data: U.S. Geological Survey Oper-File 

Report 95-399, 113 p.

Lapham, W.W., Wilde, F.D., and Koterba, M.T., 1995, 

Ground-water-data collection and procedures for 

the National Water-Quality Assessment 

Program Selection, installation, and 

documentation of wells, and collection of related 

data: U.S. Geological Survey Open-File Report

95-398, 69 p.

Patton, C.J. and Truitt, E.P., 1992, Methods of analysis 

by the U.S. Geological Survey National Water 

Quality Laboratory Determination of totr 1 

phosphorus by a Kjeldahl digestion method and an 

automated colorimetric finish that includes 

dialysis: U.S. Geological Survey Open-FiH 

Report 92-146, 39 p.

Pritt, J.W., and Raese, J.W., 1992, Quality

assurance/quality control manual, National Water 

Quality Laboratory: U.S. Geological Survey 

Open-File Report 92-495, 15 p.

30
Rose, D.L., and Schroeder, M.P., 1995, Methods of 

analysis by the U.S. Geological Survey National 

Water Quality Laboratory Determination of 

volatile organic compounds in water by purge and 

trap capillary gas chromatography/mass 

spectrometry: U.S. Geological Survey Open-File 

Report 94-708, 26 p.

Stoner, J.D. and Lorenz, D.L., 1995, National WaterQuality Assessment Program Data collection in 

the Red River of the North Basin, Minnesota, 

North Dakota, and South Dakota, 1992-95: U.S. 

Geological Survey Fact Sheet FS-172-95, 4 p.

Thatcher, L.L., Janzer, V.J., and Edwards, K.W., 1977, 

Methods for determination of radioactive 

substances in water and fluvial sediments: U.S. 

Geological Survey Techniques of WaterResources Investigations, book 5, chapter A5, 

95 p.

Timme, P.J., 1995, National Water Quality Laboratory 

1995 services catalog: U.S. Geological Survey 

Open-File Report 95-352, 120 p.

Werner, S.L., Burkhardt, M.R., and DeRusseau, S.N., 

1996, Methods of analysis by the U.S. Geological 

Survey National Water Quality Laboratory 

Determination of pesticides in water by carbopakB solid phase extraction and high-performance 

liquid chromatography: U.S. Geological Survey 

Open-File Report 96-216, 42 p.

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

Fehlberg, K.M., 1995, Methods of analysis by the 

U.S. Geological Survey National Water Quality 

Laboratory Determination of pesticides in water 

by C-18 solid-phase extraction and capillarycolumn gas chromatography/mass spectrometry 

with selected-ion monitoring: U.S. Geological 

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

31
Supplemental Information

32
The following is a complete list of the equipment 

used for ground-water sampling by the Red River of the 

North Basin NAWQA study unit.

Sample Collection Equipment

1. Well development equipment:

1.7 in. hand pump (Brainard-Kilman)

Centrifugal pump

Inertial pump

Stop watch

Calibrated bucket

Well development log book

Orion conductivity meter

Conductivity standards

2. Sampling pump equipment:

Submersible pump (Keck, Grundfos)

Teflon tubing discharge line (3/8 in. ED), with 

Swagelock stainless steel quickconnections

Deep cycle marine battery

Battery charger

Jumper cables

Anti-back siphoning device

Generator (if required for submersible pump)

Threaded connections and tubing for domestic 

well taps

3. Field parameter measurement equipment:

Hydrolab Scout H

Flow-through chamber (Geotech)

Dissolved-oxygen meter (Orion model 820)

Dissolved-oxygen calibration chart

Barometer

Air thermometer

Conductivity meter (Orion model 124) and 

conductance standards

pH meter (Orion model 250A) and 

standardizing buffers

Manuals for meters 

Extra storage solutions

4. Pesticide sample filtration unit:

Stainless-steel filter unit

Glass-fiber baked filter (0.7 (im, 142 mm 

diameter)

Teflon tubing fittings 

Pesticide spike kit

5. Dissolved organic carbon sample filtration unit:

Silver filters (0.45 (im, 47 mm diameter) 

(Osmotics, Inc.)

Stainless-steel Gelman barrel filter unit

Deionized water

Organic blank water

Graduated cylinder, glass, 100 mL

Nitrogen gas tank

Nitrogen gas desiccant assembly

Nitrogen gas tank quick-connect assembly

Stainless steel forceps

6. Inorganic sample filtration unit:

Filters (0.45 |im, capsule or cellulose nitrate 

filter papers)

7. Sample collection equipment:

Flow manifold 

Sample-collection chamber

Clear 50 in. by 50 in., plastic bags for samplecollection chambers

Trays to hold sampling equipment and sample 

bottles

Teflon connector tubing with quick connects

Rigid polycarbonate bell and corrugated Teflon 

tubing

Radon sample-collection assembly

Radon syringe and needles for radon asserrbly

Squeeze bottles for methanol and organic blank 

water

8. Alkalinity titration equipment:

Digital titrator (Hach)

Acid cartridges for digital titrator, 0.16 and 1.6 

normality H2SO4 (sulfuric acid)

Delivery tubes for acid cartridges 

Beaker, glass, 250 mL 

Graduated cylinder, glass, 100 mL

33
Battery powered magnetic stirrer 

Teflon-coated magnetic stir bars

pH meter (Orion 250A) and standardizing 

buffers

9. Sample Preservation Supplies and Apparatus:

HgCl2 (mercury chloride) ampoules 

HNC>3 (nitric acid) ampoules, 1 mL 

HNC>3 ampoules, 2 mL 

Sample-preservation chamber

Clear 50 in. by 50 in. plastic bags for samplepreservation chambers

Coolers with ice

Decontamination Supplies

1. Decontamination Supplies:

Disposable single-use latex gloves 

(powderless)

Washbasins for cleaning

Teflon pump standpipe

Detergent (Liquinox)

Sponges

Brushes for cleaning

Squeeze bottles

Tap water

Deionized water

Methanol, HPLC grade

Methanol waste bottle

Powderless laboratory tissues (Kimwipes)

Paper towels

Cloth towels

Aluminum foil

Garbage bags

Sample Shipping and Other Supplies

1. Sample shipping supplies:

Coolers 

Strapping tape 

Overnight shipping forms 

Analytical service request forms 

Return address labels

Cardboard boxes

Plastic garbage bags (large and small) 

Scalable plastic bags 

2. Other supplies:

Inorganic blank water

Organic blank water

Sample bottles

Bottle labels

Indelible markers

E-line, for measuring water levels

Steel tape, for measuring water levels

Field notebook

Field note forms

Well information

Sampling protocols

Calculator

Camera

Film

Maps

Safety goggles

Knife

Batteries (D cell, 9V, AA)

Garden hose

34