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

Open-File Report 95-399

NATIONAL WATER-QUALITY ASSESSMENT PROGRAM

National Water-Quality Assessment Study Unit
GROUND-WATER DATA-COLLECTION PROTOCOLS AND PROCEDURES

FOR THE NATIONAL WATER-QUALITY ASSESSMENT PROGRAM:

COLLECTION AND DOCUMENTATION OF WATER-QUALITY

SAMPLES AND RELATED DATA

By Michael T. Koterba, Franceska D. Wilde, and Wayne W. Lapham

______________________________________________________________

U.S. Geological Survey

Open-File Report 95-399

Reston, Virginia

1995
U.S. DEPARTMENT OF THE INTERIOR

BRUCE BABBITT, Secretary Seal

U.S. GEOLOGICAL SURVEY

Gordon P. Eaton, Director

Any use of trade, product, or firm names in this publication is for descriptive purposes only

and does not imply endorsement by the U.S. Government.

_________________________________________________________________________

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

NAWQA - Mail Stop 413 U.S. Geological Survey

U.S. Geological Survey Earth Science Information Center

12201 Sunrise Valley Drive Open-File Reports Section

Reston, Virginia 22092 Box 25286, MS 517

Denver Federal Center

Denver, Colorado 80225
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 watersupply facilities; and research on factors that affect

water quality. An additional need for water-quality

information is to provide a basis on which regionaland 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

water-quality 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 waterquality 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 NationÕs 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 resources.

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

occurs within the 60 study units and more than twothirds 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 program.

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 causes.

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

(signed)
CONTENTS

Page

Foreword............................................................................................................................ iii

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

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

Background.................................................................................................................. 2

Purpose and scope ....................................................................................................... 3

Quality assurance and quality control ......................................................................... 3

Acknowledgments ...................................................................................................... 4

Collection and documentation of water-quality samples and related data ......................... 5

Data-quality requirements ........................................................................................... 5

Plans and preparations................................................................................................. 8

Site visits.............................................................................................................. 9

Selection and purchase of equipment and supplies ............................................. 9

Pump systems .............................................................................................. 17

Field instruments ......................................................................................... 20

Water-quality vehicles.................................................................................. 22

Storage facilities ........................................................................................... 23

Timing of purchases ..................................................................................... 23

Training................................................................................................................ 24

Field evaluation.................................................................................................... 24

Design of ground-water-quality sampling schedules........................................... 26

Design of quality-control sampling and schedules ............................................. 30

Routine quality-control-samples: type, number, site selection, and timing . 33

Example of routine quality-control design: a case study ............................. 39

Topical quality-control samples .................................................................. 42

Sample coding and data management ................................................................. 42

Final presampling plans and preparations ........................................................... 48

Field protocols and recommended procedures ........................................................... 51

Equipment setup................................................................................................... 52

Well purging, grab samples, and field measurements ........................................ 52

Acceptable deviations from standard purge protocols ................................ 56

Purging with different flow rates ................................................................. 58

Purging different types of wells ................................................................... 59

Grab samples for titrations and volatile-sample preservation ..................... 61

Final assessment of chemical stability ......................................................... 63

Sample collection and processing........................................................................ 63

Field-team functions..................................................................................... 68

Special considerations for selected sample types......................................... 68

Decontamination of field equipment ................................................................... 70

Preparation of blank samples .............................................................................. 76

Preparation of other routine quality-control samples and field extracts

of pesticide samples...................................................................................... 76

Pesticide and volatile-organic-compound (VOC) spiked samples .............. 80

Pesticide solid-phase extractions ................................................................. 80

VOC trip-blank and trace-element standard reference samples ................... 82

Handling and shipping of samples....................................................................... 82

References cited ................................................................................................................. 84

Appendix. Examples of field forms for the collection of ground-water data and

 samples for the National Water-Quality Assessment Program........................ 87

iv
ILLUSTRATIONS

Page

Figure 1. Distribution of wells selected for pesticide field spikes in relation to the

major-ion composition of (A) natural and agriculturally affected groundwaters, and (B) ground-water samples in which pesticides were

detected in the Delmarva Peninsula ................................................................. 40

2. Schematic of equipment setup for well purge and sample collection............... 55

TABLES

Page

Table 1. Summary of current (1995) required, recommended, and optional waterquality constituents to be measured in the three ground-water components

of the Occurrence and Distribution Assessment, National Water-Quality

Assessment Program......................................................................................... 6

2. Information to obtain when planning water-quality data-collection activities . 10

3. Equipment, supplies, and suppliers for ground-water-quality sampling for

the National Water-Quality Assessment Program ............................................ 11

4. Example of a method to determine pump-system suitability as a function

of selected well and pump characteristics......................................................... 18

5. Requirements for meters and sensors used for field measurements taken

at ground-water-quality sites of the National Water-Quality Assessment

Program ............................................................................................................ 21

6. Recommended sequence of training-related activities to prepare for

National Water-Quality Assessment (NAWQA) Program ground-waterquality data collection....................................................................................... 25

7. Example of a sampling schedule for a 28-well Land-Use Study...................... 27

8. Basic considerations in designing annual ground-water-quality sampling

schedules for Study-Unit components of the National Water-Quality

Assessment Program......................................................................................... 28

9. Requirements for the design of National Water-Quality Assessment

Program ground-water-quality sampling schedules to enhance data quality.... 29

10. Quality-control samples for ground-water components of the National

Water-Quality Assessment (NAWQA) Program.............................................. 31

11. Procedures to identify the type and schedule the annual collection of

routine quality-control data for ground-water components of the

National Water-Quality Assessment Program.................................................. 34

12. Required type and minimum number (or frequency) of routine qualitycontrol samples for a Land-Use Study of the National Water-Quality

Assessment Program......................................................................................... 35

13. Well- and site-selection criteria for routine quality-control samples

collected for ground-water components of the National Water-Quality

Assessment Program......................................................................................... 36

14. Sample container coding requirements for ground-water-quality and

routine quality-control samples of the National Water-Quality Assessment

(NAWQA) Program.......................................................................................... 43

15. Storage and coding requirements for ground-water-quality and

quality-control samples and data of the National Water-Quality

Assessment Program......................................................................................... 45

16. Activities related to final plans and preparations before sampling begins ....... 49

v
TABLES--Continued

Page

17. Initial field-team setup activities related to on-site protocols and procedures

at wells used for ground-water-quality and routine quality-control data

collection for the National Water-Quality Assessment Program...................... 53

18. Field-team activities for purging a well for water-quality and qualitycontrol data collection....................................................................................... 54

19. Standard protocols and recommended procedures for conducting and

assessing well purging for the National Water-Quality Assessment Program . 57

20. Field-titration procedures for ground-water samples from the National

Water-Quality Assessment Program................................................................. 62

21. Collection order, processing, preservation, and field storage required

for ground-water-quality and replicate samples for the National WaterQuality Assessment Program............................................................................ 64

22. Decontamination of small equipment used for sample collection.................... 71

23. Decontamination of setup equipment used for sample collection .................... 72

24. Estimation of decontamination solution volumes for standpipe and

sample-wetted tubing........................................................................................ 75

25. Field-blank sample-collection protocols and procedures for ground-water

components of the National Water-Quality Assessment Program ................... 77

26. Sample handling for shipment of ground-water-quality and quality-control

samples.............................................................................................................. 83

vi
CONVERSION FACTORS AND ABBREVIATIONS

___________________________________________________________________________________________

Multiply By To obtain

___________________________________________________________________________________________

Length

inch (in) 25.4 millimeter

2.54 centimeter

foot (ft) 0.3048 meter

mile (mi) 1.609 kilometer

Area

square mile (mi2) 2.590 square kilometer

Volume

gallon (gal) 3.785 liter

3785 milliliter

Flow

gallon per minute (gal/min) 0.06308 liter per second

Physical and Chemical Water-Quality Units

Temperature: Water and air temperature are given in degrees Celsius (°C), which can be

converted to degrees Fahrenheit (°F) by use of the following equation:

°F = 1.8(°C) + 32

Specific electrical conductance of water is expressed in microsiemens per centimeter at 25

degrees Celsius (μS/cm). This unit is equivalent to micromhos per centimeter at 25 degrees

Celsius.

method detection limit (MDL): The minimum concentration of a substance that can be identified,

measured, and reported with 99-percent confidence that the analyte concentration is greater than

zero; determined from analysis of a sample in a given matrix containing analtye.

minimum reporting level (MRL): The smallest measured concentration of a constituent that may

be reliably reported using a given analytical method. In many cases, the MRL is used when

documentation for the method detection limit is not available.

micrometer (μm), or “micron”: The millionth part of the meter--the pore diameter of filter

membranes is given in micrometer units.

milligrams per liter (mg/L) or micrograms per liter (μg/L): Milligrams per liter is a unit expressing the concentration of chemical constituents in solution as weight (milligrams) of solute per

unit volume (liter) or water. One thousand micrograms per liter is equivalent to one milligram per liter. For concentrations less than 7,000 mg/L, the numerical value is the same as for

concentrations in parts per million.

millivolt (mV): A unit of electromotive force equal to one thousandth of a volt.

vii
CONVERSION FACTORS AND ABBREVIATIONS--Continued

nephelometric turbidity unit (NTU): A measure of turbidity in a water sample, roughly equivalent to Formazin turbidity unit (FTU) and Jackson turbidity unit (JTU).

normality, N (equivalents/L): The number of equivalents of acid, base, or redox-active species

per liter of solution. Examples: a solution that is 0.01 formal in HCl is 0.01 N in H+. A

solution that is 0.01 formal in H2SO4 is 0.02 N in H+.

____________________________________________________________________________

viii
1

GROUND-WATER DATA-COLLECTION PROTOCOLS AND PROCEDURES

FOR THE NATIONAL WATER-QUALITY ASSESSMENT PROGRAM:

COLLECTION AND DOCUMENTATION OF WATER-QUALITY SAMPLES

AND RELATED DATA

By Michael T. Koterba, Franceska D. Wilde, and Wayne W. Lapham

ABSTRACT

Protocols for ground-water sampling are described in a report written in 1989 as part of the

pilot program for the National Water-Quality Assessment (NAWQA) Program of the U.S. Geological Survey (USGS). These protocols have been reviewed and revised to address the needs

of the full-scale implementation of the NAWQA Program that began in 1991. This report, which

is a collaborative effort between the NAWQA Program and the USGS Office of Water Quality,

is the result of that review and revision.

This report describes protocols and recommended procedures for the collection of waterquality samples and related data from wells for the NAWQA Program. Protocols and recommended procedures discussed include (1) equipment setup and other preparations for data collection; (2) well purging and field measurements; (3) collecting and processing ground-waterquality samples; (4) equipment decontamination; (5) quality-control sampling; and (6) sample

handling and shipping.

INTRODUCTION

The full-scale implementation of the National Water-Quality Assessment (NAWQA)

Program in 1991 required updating the ground-water protocols prepared for the NAWQA pilot

program (Hardy and others, 1989) and more detailed information for collecting ground-waterquality data in the NAWQA Program. That effort has resulted in this report and a companion

report by Lapham and others (in press). Broader based reports that establish and document

ground-water data-collection protocols and procedures for all U.S. Geological Survey (USGS)

programs include Radtke and Wilde (in press) and two planned companion reports.1

This report describes protocols and recommended procedures for collecting ground-waterquality samples and related data (hereafter referred to as ground-water-quality data) specifically

for the Occurrence and Distribution Assessment component of the full-scale NAWQA Program.

In addition to updating and expanding the report by Hardy and others (1989), this report complements other reports prepared for the NAWQA Program, including those that describe

NAWQA well installation, selection, and documentation (Lapham and others, in press), design

of the NAWQA Program (Gilliom and others, 1995; Alley and Cohen, 1991), the conceptual

1For further information about the status of these planned reports contact the Office of Water Quality,

U.S. Geological Survey, 412 National Center, Reston, VA 22092.
2

 framework of the NAWQA Program (Leahy and Wilber, 1991; Hirsch and others, 1988; Cohen

and others, 1988), an implementation plan for the NAWQA Program (Leahy and others, 1990),

and a description of a quality-assurance (administrative) plan for the NAWQA pilot program

(Mattraw and others, 1989).

For the purposes of this report, a protocol identifies a course of action that is mandatory

under most circumstances as a consequence of USGS and NAWQA policies. For example, the

routine collection of quality-control samples throughout the period during which ground-waterquality data are being collected is a protocol, and the requirement that equipment be decontaminated between uses according to prescribed methods to avoid cross-contamination of waterquality samples and the wells being sampled is a protocol. A recommended procedure is one

that generally is preferred over other procedures that are available or commonly used. A procedure generally is recommended for the purpose of conforming to rules for good field practices

and is expected to result in reproducible data of a desired and defined quality. Recommended

procedures are not protocols because they are either too restrictive or possibly inappropriate in

some situations. For example, one recommended procedure is to measure the water level in the

well before ground-water-quality data are collected; this is not possible for some water-supply

wells. Another recommended procedure is that equipment decontamination, which is required,

be conducted in the field immediately after use; this, however, is not possible for some field-site

conditions.

Although modifications are likely as new technologies evolve, the protocols and recommended procedures for data collection and documentation described in this report are considered

capable of producing representative data of known quality that are suitable for assessment, while

also being feasible to employ, given limitations of time and funds. Their use promotes consistency and comparability of ground-water data among Study Units in the NAWQA Program.

Background

The USGS began full-scale implementation of the NAWQA Program in 1991. The goals

of the NAWQA Program are to (1) provide a nationally consistent description of current waterquality conditions for a large part of the Nation's water resources; (2) define long-term trends in

water quality; and (3) identify, describe, and explain major factors that could affect observed

water-quality conditions and trends (Hirsch and others, 1988).

The design concepts of the NAWQA Program are based in part on a pilot program that

began in 1986. The NAWQA pilot program consisted of seven Study Units conducting waterquality assessment in separate study areas. These study areas were distributed geographically

throughout the continental United States and represented diverse hydrologic environments and

water-quality conditions. Four of the pilot assessments focused on surface water and three

focused on ground water. The ground-water pilot study areas were the Carson River Basin in

Nevada and California (Welch and Plume, 1987); the Central Oklahoma Aquifer in Oklahoma

(Christenson and Parkhurst, 1987); and the Delmarva Peninsula in Delaware, Maryland, and

Virginia (Bachman and others, 1987).
3

The NAWQA Program design that has evolved from the pilot program consists of two

major components: (1) Study-Unit Investigations of both surface and ground water, and (2)

National Assessment activities, which combine results of individual Study Units for selected

topics. This design provides information on water quality for policymakers and managers at

local, State, regional, and national scales.

Components and attributes of the current ground-water-sampling design for a Study Unit

are described in Lapham and others (in press) and Gilliom and others (1995). In brief, for the

full-scale NAWQA Program, investigations of 60 Study Units, ranging in area from 1,200 to

more than 60,000 square miles, are ongoing or planned. The 60 Study Units include parts of

most of the major river basins and aquifer systems in the Nation, and incorporate about 60 to 70

percent of the Nation's water use and population served by public water supply. Investigations

in each Study Unit are being conducted on a rotational rather than a continuous basis. One-third

of the Study Units are being studied intensively at any given time. For each Study Unit, a 3-

to 4-year intensive period of data collection and analysis will be alternated with a 6- to 7-year

period of low-intensity assessment activities. The first intensive period of study for 20 of the 60

Study Units, which is referred to as the Occurrence and Distribution Assessment, began in 1993.

Data from each Occurrence and Distribution Assessment will be aggregated and compared

for selected topics from all Study Units, as well as from other programs, to obtain regional and

national perspectives on water quality. Consistent methods of data collection by the Study Units

are needed for comparability of data. The protocols and recommended procedures described in

this report are intended to ensure that consistency.

Purpose and Scope

This report describes protocols and recommended procedures to be used by the NAWQA

Program for the collection of ground-water-quality data from wells. Protocols and recommended procedures discussed relate to the plans and preparations for ground-water sampling, and

the collecting, processing, and handling of ground-water samples, including well purging, field

measurements taken during purging, equipment decontamination, quality-control sampling, and

sample documentation, handling, and shipping. Quality-assurance protocols and procedures are

incorporated for each data-collection activity.

Quality Assurance and Quality Control

In this report, quality assurance refers to activities that control or guide data-collection

methods, such as protocols, recommended procedures, and work plans and schedules. Quality

control refers to the data or measurements generated to quantify measurement bias and variability associated with the data-collection process. The quality assurance (QA) activities and quality

control (QC) data associated with NAWQA protocols and recommended procedures described

in this report are best carried out as an integral part of the plans, preparations, implementation,

and documentation used to obtain ground-water-quality data (Shampine and others, 1992). To

emphasize the importance of an integrated approach, and the need for all NAWQA ground-water

staff to participate, the protocols and recommended procedures that relate to QA and QC appear
4

throughout this report in relation to a variety of responsibilities and activities, rather than being

segregated in a separate section.

An integrated approach to QA and QC helps to clarify what needs to be done, when, and

by whom through QA activities that are logically and efficiently coordinated with other activities

and through the collection of data to assess that the ground-water data collected are of a quality

suitable for Study-Unit and National Assessments. In order of discussion, the data-quality

requirements for NAWQA ground-water sampling and the role of QC sampling are described in

“Data-Quality Requirements.” Equipment and supplies specific to QC sampling are described,

along with those generally required to obtain water-quality data, in “Selection and Purchase

of Equipment and Supplies.” The QA requirements for field instruments and water-quality

vehicles are incorporated under the respective topics (see “Field Instruments” and “WaterQuality Vehicles”). The design for selecting QC sample types and scheduling their collection

are described immediately following the discussion of the design of water-quality sampling

schedules.

Protocols and recommended procedures to be followed in collecting QC samples are incorporated as part of a number of activities that occur in chronological order and that define the

overall data-collection process at a well. For example, the collection of replicate ground-water

samples is described after well purging, and as part of the discussion on the collection of waterquality samples (see “Sample Collection and Processing”), whereas the collection of field blanks

is described after equipment decontamination (see “Preparation of Blank Samples”). Preparing

special types of samples, including QC samples such as field spikes, is described after the section

on field blanks because that is when field-spiked samples for pesticides and volatile organic

compounds will be prepared (see “Preparation of Other Routine Quality-Control Samples and

Field Extracts of Pesticide Samples”). Finally, documentation activities relating directly to QA

and QC are described throughout this report.

Although this report includes many QA-QC protocols and recommended procedures, it

does not replace the need for individual Study Units to assess, review, and possibly expand on

those described. Study Units are encouraged to publish their QA-QC plans and results independent of any work performed at the national level of the NAWQA Program, and as appropriate

for their particular needs.

Acknowledgments

The authors gratefully acknowledge the contributions and assistance of many colleagues

within the USGS in producing this document. In particular, thorough and thoughtful reviews and

discussions were provided by Mark A. Hardy, William H. Werkheiser, and Neil M. Dubrovsky

of the USGS on preliminary drafts, and by David W. Clark, Dorinda J. Gellenbeck, and W. Brian

Hughes of the USGS National Water-Quality Assessment Program on subsequent drafts of this

report. Editorial assistance was provided by Iris M. Collies.
5

COLLECTION AND DOCUMENTATION OF WATER-QUALITY

SAMPLES AND RELATED DATA

Ground-water-quality data for the Occurrence and Distribution Assessment of the

NAWQA Program are to be collected and documented in accordance with the specific protocols

and recommended procedures described in this report and in Lapham and others (in press). Protocols and recommended procedures are provided that cover plans and preparations, collection

methods, and the documentation of activities before, during, and after water-quality data are collected. The principles underlying these protocols and recommended procedures have been

shown to produce data suitable for the Occurrence and Distribution Assessments of NAWQA in

selected pilot areas (Christenson and Rea, 1993; Hamilton and others, 1993; Koterba and others,

1993; and Rea, in press).

The NAWQA ground-water protocols and recommended procedures are applicable for

data commonly collected for all three ground-water components (Study-Unit Surveys, Land-Use

Studies, and Flowpath Studies) of the NAWQA Program (table 1). Although they are consistent

with general guidelines for USGS ground-water data collection (F.D. Wilde, U.S. Geological

Survey, written commun., 1995--see footnote 1), these protocols and recommended procedures

reflect NAWQA Program objectives, and could differ in some aspects from those of other USGS

programs. In particular, because of the perennial nature of the NAWQA Program, methods used

by individual Study Units are constrained by the need for national consistency in the quality of

data collected and by the degree and type of documentation required.

Data-Quality Requirements

The importance of national consistency in data collection cannot be overstated. Inconsistent methods can lead to variable and biased data measurements.2 Modifications to collection

and analytical methods potentially result in data whose measurements vary or are biased in relation to previously collected data. If not quantified and documented, such modifications complicate trend analysis (Smith and Alexander, 1989).

The protocols and recommended procedures for NAWQA are designed to reduce inconsistencies and enhance the quality of data used in spatial and trend analysis. The purpose of dataquality requirements is to ensure that data-collection methods are consistent, and that the data

obtained meet study needs. The NAWQA Program has three requirements related to sample collection: (1) document the methods used to collect ground-water-quality data and all qualityassurance and quality-control measures, (2) ensure that the quality of data collected is known,

and (3) demonstrate that the quality of data obtained is suitable for assessment objectives. In

meeting these requirements, it is necessary that data-collection and analytical methods be designed, planned, and executed as consistently as possible. This will help reduce bias and variability among the data collected within a single Study Unit and among Study Units.

2The term “bias” is defined in this report as a systematic error that is manifested as a consistent positive

or negative deviation from the known or true value. “Variability” is defined as measurement reproducibility

or the degree of similarity among independent measurements of the same quantity, often measured as a variance or relative standard deviation and without reference to the known probable or true value.
6

Table 1. Summary of current (1995) required, recommended, and optional water-quality constituents

to be measured in the three ground-water components of the Occurrence and Distribution Assessment,

National Water-Quality Assessment Program (from Lapham and others, in press)

[Required water-quality constituents to be measured for the Occurrence and Distribution Assessment are

determined partly by the water-quality topics of national interest selected for National Assessment.

Topics selected for National Assessment (1994) are nutrients, pesticides, and volatile organic compounds. The topics selected can change over time. Quality-control samples also are required - types of

quality-control samples depend on study component. Req, Required; Rec, Recommended; Opt, Optional;

NWQL, National Water Quality Laboratory; SC, Schedule; LC, Laboratory Code]

Water-quality constituent

or constituent class

Study-Unit

 Survey

Land-Use

 Studies

Flowpath

 Studies1 Method2

Field measurements

 - Temperature Req Req Req Field

 - Specific electrical

 conductance Req Req Req Field

 - pH Req Req Req Field

 - Dissolved oxygen Req Req Req Field

 - Acid neutralizing

 capacity (ANC)

 (unfiltered sample)3 Rec Rec Rec

 Field

 incremental

 - Alkalinity

 (filtered sample)3 Req Req Req Field

incremental

 - Turbidity4 Rec Rec Rec Field

Major inorganics Req Req Req NWQL SC2750

Nutrients Req Req Req NWQL SC2752

Filtered organic carbon Req Req Opt NWQL SC2085

Pesticides Req Req Opt NWQL SC2001/2010

NWQL SC2050/2051

Volatile organic

 compounds (VOCs) Req Req or Opt5 Req or Opt6 NWQL SC 2090

Radon Req Req or Rec7 Req or Rec6 NWQL LC 1369

Trace elements4 Opt Opt Opt NWQL SC 2703

Radium Opt Opt Opt NWQL-Opt

Uranium Opt Opt Opt NWQL-Opt

Tritium, tritium-helium,

 chlorofluorocarbons (CFCs)8 Rec Rec Rec

NWQL LC1565

(tritium)

Environmental isotopes9 Rec Rec Rec NWQL-Opt
7

Table 1. Summary of current (1995) required, recommended, and optional water-quality constituents

to be measured in the three ground-water components of the Occurrence and Distribution Assessment,

National Water-Quality Assessment Program (from Lapham and others, in press)--Continued

_________________________________________________________________________________

1Selection of constituents for measurement in Flowpath Studies is determined by FlowpathStudy objectives. During at least the first round of sampling, however, the broad range of

constituents measured in Study-Unit Surveys and Land-Use Studies will be measured.

2Schedules and laboratory codes listed are required for Study Units that began their intensive

phase in 1991 or 1994, and apply until changed by National Program directive. Schedules for

radium and uranium can be selected by the Study Unit, but require NAWQA Quality-Assurance

Specialist approval. A detailed discussion is found in the “Sample Collection and Processing”

section of this report.

3ANC (formerly referred to as unfiltered alkalinity) is measured on an unfiltered sample.

Alkalinity is measured on a filtered sample. A Study Unit could have collected ANC, alkalinity,

or both to date.

4Turbidity measurements are required whenever trace-element samples are collected to

evaluate potential colloidal contributions to measured concentrations of iron, manganese, and

other elements.

5VOCs are required at all urban Land-Use Study wells, but are optional in agricultural LandUse Studies. If VOCs are chosen as part of an agricultural Land-Use Study, then they should be

measured in at least 20 of the Land-Use Study wells.

6VOCs are required at all urban flowpath wells for at least the first round of sampling. If

VOCs are measured in an agricultural Land-Use Study, then they should be measured at all

Flowpath-Study wells within that Land-Use Study for at least the first round of sampling.

7Radon is required at any Land-Use or Flowpath Study well if that well also is part of a StudyUnit Survey; otherwise radon collection is recommended for Land-Use or Flowpath-Study wells

located in likely source areas.

8Collection of tritium, tritium-helium, chlorofluorocarbons (CFCs), and (or) other samples

for dating ground water is recommended, depending on the hydrogeologic setting. For tritium

methods, see NWQL catalog; for CFCs, see Office of Water Quality Technical Memorandum

No. 95.02 (unpublished document located in the USGS Office of Water Quality, MS 412,

Reston, VA 22092).

9For a general discussion of the use of environmental isotopes in ground-water studies, see

Alley (1993).
8

This report comprises a substantial part of the documentation requirement. Because of diverse site conditions, well types, equipment requirements, and staff experience, situations could

arise where NAWQA protocols and recommended procedures described in this report need to be

modified. Modifications at the program level will be made in a systematic manner and initially

documented through internal, regional, or national memorandums. For modifications internal to

Study Units, the chief of the Study Unit is responsible for ensuring that the proposed modification is discussed with the NAWQA Program Quality-Assurance (QA) Specialist before implementation, and that any modifications used are clearly documented in Study-Unit publications.

It also is necessary for the NAWQA Program or individual Study Units to provide evidence of

the effect, or lack thereof, of modifications on data quality.

To ensure data quality and suitability (the second and third data-quality requirements) each

Study Unit will routinely follow protocols and recommended procedures that are described in

detail in the following sections. The QA-QC measures include (1) the collection of selected QC

samples in the field to test equipment and methods before data collection begins, and (2) the routine collection of selected QC samples (such as blanks, replicates, and spiked replicate samples)

during ground-water-quality sampling. Additional QC samples and QA measures will be taken

if modifications in methods of sample and data collection occur that require quantification.

Individual NAWQA Study Units or National Synthesis teams may find it necessary to

expand QC data collection to identify specific sources of measurement bias or variability. In

addition, it has been necessary in some cases to enhance collection of QC data in order to interpret the corresponding ground-water-quality data (Koterba and others, 1991; Ferree and others,

1992; and Koterba and others, 1994). Study-Unit and National-Synthesis-Team budgets, plans,

and preparations need to remain flexible to allow for the possibility that additional QC data could

be needed.

Plans and Preparations

Plans and preparations for ground-water sampling are completed well in advance of datacollection activities, yet must remain flexible enough to be modified if circumstances dictate.

Preparations include becoming familiar with the protocols and recommended procedures described in this document. Sampling equipment and supplies need to be obtained in time for sampling and for the staff to be trained in their use. The ground-water staff also needs to become

familiar with and develop the documentation and management of samples and data, including

that for QC samples. Finally, the ground-water staff should make detailed plans and preparations

for the first field season, which for most Study Units commonly will begin early in the first year

of the Occurrence and Distribution Assessment.

As the Study-Unit Investigation progresses, subsequent plans and preparations for each

field season are required annually, and are developed as part of the general workplan. Study

Units commonly will complete preparations for sampling several weeks in advance of each field

season. Documenting site conditions, water-quality data collection, and reviewing collected data

are processes that begin before each field season, continue during data collection, and often

extend months beyond each field season.
9

Five key elements to consider in the initial and (in some cases) annual plans and preparations include (1) site visits to assess conditions that could affect sample and data collection; (2)

selecting and obtaining sampling equipment and supplies early, to ensure that those eventually

used best meet field conditions and fall within NAWQA Program requirements or recommendations; (3) training, to prepare field teams; (4) conducting a field evaluation, to determine that the

equipment and procedures will provide high-quality data and that planned documentation and

management activities are adequate; and (5) developing detailed schedules that clearly describe

staff responsibilities before, during, and after each field season. Each of these planning and preparation elements is described below in detail.

Site Visits

Wells selected or installed for each ground-water component are visited at least once before

sampling. During this or any other visit, site data are reviewed to determine if information is

needed to (1) complete documentation requirements (Lapham and others, in press), and (2)

plan water-quality sampling activities (table 2). In addition, plans currently (1995) are being

developed for screening wells for high concentrations (10 μg/L or greater) of volatile-organiccompound (VOC) contamination (John Zogorski, VOC National Synthesis Team, U.S. Geological Survey, written commun., 1995). This could add to the information that needs to be collected during these site visits for selected wells sampled after 1995.

Selection and Purchase of Equipment and Supplies

Because of the need to obtain nationally consistent data over many years on a wide variety

of chemical constituents (table 1), most equipment and supplies not provided by the Study Unit

generally should be obtained from one of three USGS suppliers: the Hydrologic Instrumentation

Facility, Quality Water Service Unit, and National Water Quality Laboratory (table 3). Each of

these suppliers offers the advantage of stocking equipment that otherwise would have to be

obtained from multiple sources. These suppliers also conduct QC checks and provide QC data

for selected supplies and equipment distributed to USGS personnel. For these reasons, these suppliers are designated as the required or sole-source supplier for such items (table 3, USGS supplier with “S” designation). The USGS suppliers also are recommended as sources for other

equipment (table 3, USGS supplier with “R” designation) in order to reduce the time, effort,

paperwork, and cost to the Study Unit to locate and obtain equipment. Should the need arise,

each supplier also can provide equipment not previously available.
10

Table 2. Information to obtain when planning water-quality data-collection activities

______________________________________________________________________________

1. Type of Well Hookup for Sampling: Determine if a hookup to a garden-hose-threaded

flow valve (common for water-supply wells) or to a portable, submersible pump (common

for monitoring wells) is needed for sample collection.

2. Depth Measurements: Measure the depth of the well and depth to the water level in the

well to check well-construction integrity and to determine pump lift, height of water column,

volume of standing water held in the well, and purge volume.1

3. Site Conditions and Restrictions: Note road or access conditions to the well, areas of

low clearance, limits on arrival and departure times, or presence of roaming animals (for

example, livestock or pets) that could create problems for a field team.

4. Contact Person: Obtain land- or well-owner name and telephone numbers (business and

home) and contact owner before or upon arrival, and perhaps upon departure.

5. Local Maps and Photographs: Locate well on maps, site sketches, or photographs, and

indicate the measuring point for well-depth measurements, as well as areas for equipment

setup and waste discharge.

6. Travel Maps and Travel Times: Identify route and travel times from District office or

previous site, and possible tunnel or bridge restrictions on the transport of gasoline,

bottled gas, or methanol (or other organic cleaning agent).

______________________________________________________________________________

1Measurements are made in accordance with National Water-Quality Assessment Program and

U.S. Geological Survey protocols (Lapham and others, in press). Purge volume is defined as three

times the volume of standing water in the well casing or, in absence of a casing, the borehole.
11

Table 3. Equipment, supplies, and suppliers for ground-water-quality sampling for the National

Water-Quality Assessment Program

[OM, open market; HIF, U.S. Geological Survey Hydrologic Instrument Facility, Stennis Space Center,

Miss.; R, recommended supplier; QWSU, Quality Water Service Unit, Ocala, Fla,; SU, Study Unit; μm,

micrometer; mm, millimeter; S, sole (required) source of supplies indicated; NWQL, National Water

Quality Laboratory, Arvada, Colo.; mL, milliliter; L, liter; ASTM, American Society for Testing and

Materials; SC, NWQL analytical schedule; FA, filtered and acidified sample; FU, filtered (unacidified)

sample; RU, raw (unfiltered) sample; FCC, filtered, chilled (no preservative added) sample; μS/cm,

microsiemens per centimeter at 25 degrees Celsius; mg/L, milligrams per liter; DIW, deionized water;

BTD&QS, Branch of Technical Development and Quality Systems, Arvada, Colo.] _____________________________________________________________________________________

Equipment and supplies Suppliers

_____________________________________________________________________________________

1. Well-head setup or connection

• Monitoring well: submersible pump and reel system OM1

• Water-supply well: hook-up segment with garden-hose thread HIF2, R

2. Sample-flow transfer system from pump reel to collection point

• Antibacksiphon device, Teflon, connected in line HIF, R3

• Extension lines for sample flow, Teflon, with connectors HIF, R

• Manifold, with connectors and Teflon valves, for routing sample flow HIF, R

• Sample-collection equipment that has connectors to manifold:

Radon collector with septa, and connectors to manifold HIF, R

Glass syringe with leur-locked stainless-steel needles QWSU, R

Teflon, line with connector to manifold, either open ended for turbidity HIF, R

sample collection, or with connector to flowthrough turbidimeter

• Sample-collection and processing chamber frame, PVC or inert HIF, R

material with sample-flow-transfer port

• Preservation-chamber frame, PVC or inert material HIF, R

• Transparent disposable covers and plastic clips to hold covers inside SU, HIF, R4

frames for sample and preservation chamber frames

• Flowthrough chamber with field-instrument ports, manifold connections, OM5

and waste line

3. Sample-filtration equipment

Organic carbon, filtered fractions

• Stainless-steel cylinder unit with nitrogen-gas deso-quick connect, gas HIF, R

scrubber, and gas line with connector to secondary regulator

• Nitrogen gas tank, with primary and secondary regulators OM

• Filter membranes, 0.45-μm, 47-mm diameter, silver QWSU, S

• Safety belts, to secure gas tank OM

• Container, to collect spent silver nitrate membranes SU

Pesticides

• Aluminum or stainless-steel unit OM, NWQL6

• Filter membranes, 0.7-μm, 142-mm diameter, baked, GF/F grade

glass microfiber QWSU, S

• Connector from filter unit to sample-chamber outflow tube SU6
12

Table 3. Equipment, supplies, and suppliers for ground-water-quality sampling for the National

Water-Quality Assessment Program--Continued

______________________________________________________________________________

Equipment and supplies Suppliers

______________________________________________________________________________

Inorganic (major ions, nutrients, and trace elements)

• Filter units, capsule with self-contained 0.45-μm7, pleated, Supor capsule QWSU, S

• Convoluted (spiral configuration) Teflon sample-flow lines from filter OM

unit to sample-chamber outflow tube8

4. Sample Bottles (sample containers, caps, and protective foam sleeves)

Organic samples

• Volatile organic sample (SC2090), 40-mL amber vial, baked (Teflonlined cap)--three vials per sample (Also includes trip blanks.) NWQL, S

• Pesticides (SC2001 or 2010) sample: 1-L amber bottle, baked (Teflon- QWSU, S

lined cap)

• Pesticides (SC2050 or 2051) sample: 1-L amber bottle, baked (Teflon- QWSU, S

lined cap)

• Organic carbon (SC2085) samples (filtered): 125-mL, amber bottle, QWSU, S

baked (Teflon-lined cap)

• Sleeves, foam, for 40-mL, 1-L, and 125-mL containers QWSU, S

Inorganic samples

• Radon (LC1369) sample: scintillation vial (one per transport tube) NWQL, S

• Major cations (SC2750): filtered, acid-rinsed, 250-mL clear polyethylene QWSU, S

bottle (with clear cap), FA--two per sample (one archived by SU)

• Trace elements (SC2703, SC172, LC112 for arsenic and LC87 for QWSU, S

selenium for field blanks): acid-rinsed, 250-mL clear polyethylene

bottle (with clear cap), FA--one per sample

• Major anions (SC2750): 500-mL, clear polyethylene bottle labeled QWSU, S9

FU, clear 28-mm neck (with black cap)--one per sample

• Nutrients (SC2752): 125-mL amber polyethylene bottle (with black QWSU, S

cap), FCC--one per sample

• Unfiltered sample (SC2750) RU for laboratory measurements: QWSU, S

250-mL clear polyethylene bottle (with black cap)--one per sample

(Order black caps for 28-mm bottle neck separately) QWSU, S

5. Sample and Shipping Forms and Shipping Supplies

• Field form (standard National Water Quality Field Form or District analog)10SU

• Analytical Services Request (ASR) forms for NWQL NWQL, S

• Sample Reply Form (Study Unit to NWQL) and return envelope, SU

self-addressed, stamped (see appendix, fig. A20, for example)

• Overnight shipping labels Contract Carrier

• Surface-mail shipping labels (supplied and prepared at District Office) SU
13

Table 3. Equipment, supplies, and suppliers for ground-water-quality sampling for the National

Water-Quality Assessment Program--Continued

______________________________________________________________________________

Equipment and supplies Suppliers

______________________________________________________________________________

• Coolers, with latch lid and drain port, maximum loaded weight of 50-60 lbs. OM

(for overnight sample delivery)

• Heavy cardboard boxes, maximum loaded weight, 20 lbs. (surface delivery) OM

• Plastic bags, heavy, 4-mil (for holding ice and overnight samples in cooler) OM

• Plastic bags, resealable (for holding ASR and other forms mailed with samples) OM

• Filament tape (to secure lid and drain cap of cooler, and surface-delivery boxes) OM

6. Field-titration equipment11

• Digital or other titrator meeting USGS specifications QWSU, R

• Acid cartridges (for digital titrator)--0.16 and 1.6 Normal sulfuric acid QWSU, S

• Extra acid-delivery tubes for digital titrator, clear plastic QWSU, R

• Glass beakers (250 mL) OM

• Volumetric pipets, glass, Class A (for preparing filtered samples) OM

• Magnetic stirrer and small Teflon-coated stir bars OM

7. Field instruments11

• pH (electrometric) meter OM

• pH electrodes and refill solutions (specify type of electrode) QWSU, R

• Specific electrical conductance meter OM

• Dissolved-oxygen (amperometric) meter and associated equipment OM or QWSU

(sensor cable, membrane and solution kit)

• Pocket barometer (used for pressure correction to dissolved-oxygen meter) HIF, R

• Calibration wand and cup (for dissolved oxygen) HIF, R12

• Turbidity (nephelometric) meter (turbidity measurement generally is OM

recommended, but required for trace-element sampling)

• Temperature measurement: thermistor thermometer (recommended),

possibly part of other field meters. Also need a liquid-in-glass QWSU, R

thermometer, ASTM certified, 0.1°C-graduated range of -5 to 45°C OM, R

(for calibrating thermistor thermometer)

8. Miscellaneous equipment and supplies

• Parafilm HIF, R

• Forceps (tweezers), Teflon-tipped stainless steel (to handle filter membranes OM

for organic and inorganic samples); or steel forceps (for flat glass-fiber and

silver membranes) and plastic forceps (for cellulose nitrate or other inorganicsample membranes)

• Plastic beakers and small cups, used to hold solutions for calibrating or OM, R

checking field-instrument sensors
14

Table 3. Equipment, supplies, and suppliers for ground-water-quality sampling for the National

Water-Quality Assessment Program---Continued

______________________________________________________________________________

Equipment and supplies Suppliers

______________________________________________________________________________

9. Decontamination equipment and supplies • District deionized water (DIW) (conductivity ≤1 μS/cm), quality controlled SU

• Inorganic-free blank water (IBW) (quality controlled for major ions and QWSU, S13

trace elements)

• Pesticide-free blank water (PBW) or volatile and pesticide-free blank NWQL, S13

water (VPBW) (for pesticides or volatile organics) • Methanol, pesticide-grade high purity (organic-sampling equipment) OM • Laboratory detergent, phosphate free, concentrated: diluted to a QWSU, R

0.1 percent decontamination solution, by volume, with DIW • Wash bottles, polyethylene, 250 mL or 500 mL (for DIW and IBW) QWSU, R • Wash bottles, Teflon, 500 mL (for PBW and VPBW) QWSU, R • Wash bottle, for methanol or other organic solvent, 250 mL OM

• Laboratory gloves, powderless (latex or vinyl) (for decontamination

and sample collection) QWSU, R • Plastic trays (3) HIF, R

• Pump standpipes (glass graduated cylinders or pipette jars are preferred) HIF, R14

• Forced-hot-air dryer, portable, vehicle-powered (for evaporating methanol OM

residues)

• Teflon bags, small (for small organic-sampling equipment and pump intake) HIF, R

• Heavy aluminum foil (for wrapping organic-carbon and pesticide-filter-unit

inlets and outlets OM

• Plastic bags, resealable (for small inorganic sampling equipment) OM

• Plastic bags, large, for enclosing cleaned pump reel, extension lines, HIF, R

and other large equipment

• Paper tissues, lint free, soft, disposable, large and small sizes (for example, OM

Kimwipes)

10. Safety equipment OM15

• Fire extinguishers (A-B-C type) with mounts • Safety goggles or glasses • Eye-wash bottle • Emergency spill kits for any chemicals being used • Approved containers for transporting pure and used methanol • Safety cones, large

• Material Safety Data Sheets

11. Chemical reagents (kits include equipment for dispensing reagent)

Preservatives

• VOC samples (SC2090) -- 1:1 hydrochloric acid (kit) NWQL, S

• Acrolein and acrylonitrile samples (SC1401) -- 1:1 hydrochloric acid NWQL, S16

• VOC samples in chlorinated water matrix--ascorbic acid (with scoop) NWQL, S17

• Inorganic (FA) samples for major cations (SC2750) and trace elements QWSU, S18

(SC2703)--nitric acid, 1-mL glass ampoule, one per sample
15

Table 3. Equipment, supplies, and suppliers for ground-water-quality sampling for the National

Water-Quality Assessment Program--Continued

_____________________________________________________________________________

Equipment and supplies Suppliers

_____________________________________________________________________________ Standards

• pH standard buffers (pH 4, 7, and 10) QWSU, S

• Specific electrical conductance standards (50 to 50,000 μS/cm; for QWSU, S19

low-conductivity waters of ≤20 μS/cm, use pH 4.31 buffer)

• Turbidity standards--Formazin OM

• Dissolved-oxygen “zero” standard dilutions, freshly prepared with OM20

reagent grade sodium sulfite and cobalt chloride

Spike and other solutions • VOCs (SC2090, SC2091, SC2092): standard NAWQA spike solution

and spike-solution kit NWQL, S • Pesticides (SC2050 or 2051 and SC2001 or 2010): standard NAWQA

spike solution and spike-solution kits NWQL, S • Mixtures, required for trace elements (SC2703) BTD&QS, S

• IBW, PBW, VPBW (see no. 9, “Decontamination equipment and supplies”) NWQL and

QWSU, S

12. Optional Equipment21

• Equipment for isotope, radiochemical, and other special samples--for example, OM

deuterium-oxygen, tritium, uranium, radium, mercury, chlorofluorocarbons

• Field solid-phase-extraction equipment for pesticide samples NWQL, S _____________________________________________________________________________________________ 1

That meets NAWQA Program requirements; see text.

2

To remove oils and other manufacturing or shipping residues, and before assembling HIF or other equipment that

includes Teflon tubing (without metal fittings), soak tubing for 30 minutes in a 5 percent hydrochloric acid solution

rinsed with tap water until rinsate has pH similar to tap water, then final rinse three times with DIW. For a 5-percent

acid solution, add 5 milliliters of 12 normal (concentrated) acid (specific gravity 1.19 and trace-element free) to each

100 milliliters of DIW (specific conductance not to exceed 1.0 microsiemens at 25 degrees Celsius).

3

Required for each portable pump system (monitoring wells) or hook-up setup (water-supply wells). Purchase

separately from pump system; a single unit can be interchanged between portable-pump and hook-up systems.

4

Recommended design that allows cover to be attached inside frame with small, plastic clips.

5

Flowthrough chamber from HIF meets design criteria for use with individual field instruments--pH, dissolved

oxygen, specific electrical conductance, and temperature--required for ground-water-quality sample collection.

6

For aluminum filter unit purchased through NWQL that is set up for solid-phase extraction, SU supplies a short

Teflon tube (1/2-inch outer diameter, 3/8-inch inner diameter) that slips over standard nipple connection on filter unit

and is connected by a 5/8-inch outer diameter by 1/2-inch inner diameter Teflon sleeve to the tube extending from the

sample chamber frame to the filter unit.

7

For ground water that contains colloidal material, filter membranes with a pore size less than 0.45 μm are

required if the filtrate data must represent ion concentrations in solution. The filter pore size in general should not

exceed 0.2 μm.

8

Commonly sold in 5-foot lengths and can be cut into small lengths. Convoluted is preferred over corrugated

type because latter is prone to trapping sediment, and must be replaced frequently (Johnson and Swanson, 1994).

9

RU sample is not needed with trace-element schedule SC2703 if field conductivity is recorded on trace-element

ASR form, along with a notation (in comment line to laboratory) that there is “no RU sample.”
16

Table 3. Equipment, supplies, and suppliers for ground-water-quality sampling for the National

Water-Quality Assessment Program--Continued

______________________________________________________________________________

10

To be filed with ASR Forms (SU copy) every time samples are collected at well (see appendix, fig. A8, for

example).

11

Refer to table 5 and Radtke and Wilde (in press) for descriptions of equipment and equipment specifications.

12

Use air-calibration-chamber-in-water method (Radtke and Wilde, in press, Sec. 6.2).

13

IBW, PBW and VPBW are laboratory-produced waters quality-controlled for specified analyses. The primary

use of these waters is for blank samples, but they also can be used in small quantities for ultraclean decontamination

procedures. PBW and VPBW contain about 0.1 mg/L of organic carbon (NWQL Technical Memorandum 92.01--unpublished document available from NWQL, 5293 Ward Road, Arvada, CO 80002), but analyses could differ among

lots.

14

Glass is the preferred standpipe material for decontaminating pump equipment because it does not readily absorb

contaminants (Reynolds and others, 1990), especially if used repeatedly after equipment exposure to volatile

organic compounds.

15

Contact District Safety Officer for suppliers and specifications.

16

Acrolein requires careful acidification to pH between 4 and 5 (acrylonitrile can withstand acidification to pH

less than 2).

17

Only required if sample water for VOC analyses is chlorinated; ascorbic acid will be supplied with the VOC

preservative kit (NWQL) upon request. Otherwise, obtain ascorbic acid from the OM. DO NOT SUBSTITUTE

SODIUM THIOSULFATE for ascorbic acid.

18

Ultrapure nitric acid also available in 1-mL glass or Teflon ampoules.

19

Purchase standards that bracket water-quality sample values.

20

Prepare dissolved-oxygen standard solution fresh on day of use instead of repeatedly purchasing and discarding

commercially available solutions.

21

For assistance with (1) isotope, radiochemical, and other specialized equipment, contact the NAWQA Quality

Assurance Specialist; (2) solid-phase extraction equipment, contact the NWQL, Methods Research and Development

Program; and (3) chlorofluorocarbons (CFCs), contact Niel Plummer or Ed Busenberg, USGS National Research

Program, MS 432, Reston, VA 22092.
17

Equipment not commonly provided by the Study Unit or USGS suppliers usually can be

obtained on the open market (table 3, OM under supplier) and includes portable pumps for

collecting samples at monitoring wells, and field instruments, vehicles, and storage facilities

associated with ground-water-quality data collection. Each of these items is discussed separately

below.

Pump systems

Several low-discharge, submersible pumps are available for collecting water-quality

samples from wells. These pumps contain sample-wetted parts that consist mainly of Teflon and

corrosion-resistant 316-stainless steel. On the basis of pump characteristics and results from decontamination tests (F.D. Wilde, U.S. Geological Survey, written commun., 1995--see footnote

1) these pumps are suitable for collecting a wide array of samples, including those required for

NAWQA (table 1).

Use of low-discharge, submersible, portable pumps (such as the Fultz Model No. SP-300,

Keck Model No. SP-84, Grundfos Model No. Redi-Flo2, and Bennett Model No. 180 or 1800) is

required for NAWQA when sample collection from monitoring wells involves microgram-perliter concentrations of VOCs, pesticides, or possibly trace elements. These pumps also are suitable for the collection of major ion, nutrient, and selected radionuclide samples.

From among suitable pump types, the choice for each Study Unit comes down to weighing

the differences in pump performance characteristics (for example, pump diameter, lift capability,

flow rate, portability, repairability, and power requirements) against characteristics of wells in

the network (for example, well internal diameter, accessibility, purge volumes and times, and lift

requirements) to determine the pump(s) that best meet Study-Unit needs. This decision process

is illustrated for three pumps and shallow wells (table 4). (A similar process can be used to evaluate other pumps and deeper wells than those illustrated in table 4.) To select which of these

pumps best meets sampling needs, the Study Unit can compare selected pump characteristics--

primarily lift potential and pumping rate--with anticipated well or site characteristics--primarily

depth to water level (lift), purge volume, and purge time (which, for practical reasons, is best kept

to less than about 2 hours). If more than one pump type is adequate, other factors, such as repairability, power requirements, or cost can be used to refine the selection process. If most wells can

be sampled with one pump type, and only a few wells require a second pump type (for example,

deep wells), the Study Unit should consider collaborating with other Study Units or projects within the District to obtain the second pump to collect samples. (Well development is not at issue in

this discussion. Pumps to be used for the collection of water-quality samples are not designed,

and should not be used, to develop wells.)
18

1Required purge volumes (in gallons) as a function of well diameter and water-column height.

 Well diameter Water-column height (in feet)

 (in inches) 20 40 60 80 100 120 140 160 180 200 240 260

 Required purge volume (in gallons) _________________________________________________________

2 10 20 29 39 49 59 69 78 88 98 108 118

4 39 78 118 157 196 235 274 313 353 392 431 470

6 88 176 264 353 441 529 617 705 793 881 969 1,058

Where purge volume equals three times the borehole or casing volume. The borehole or casing volume,

V (in gallons), is calculated as V= 0.0408 x H x D2, where H is the water-column height (in feet), and D

is the well diameter (in inches).

2In these examples, the required lift is equivalent to total dynamic head and is estimated as the depth

to water in the well. This assumes that the purge takes place with the pump intake at the top of the water

column, and that the water level in the well does not decline appreciably with pumping. Note that for submersible pumps (for example, helical rotor gear, progressing cavity, bladder, and piston pumps) Lift =

pump depth + frictional tubing loss; for centrifugal-pump designs, this is more accurately described as total

dynamic head (TDH), where TDH = depth to water + frictional tubing loss.

Table 4. Example of a method to determine pump-system suitability as a function of selected well

and pump characteristics

[in, inches; ft, feet; gal, gallons; ---, not applicable]

Well characteristics Pump characteristics and suitability

Well

Diameter

(in)

Watercolumn

height

(ft)

Required

purge

volume1

(gal)

Required

lift or

total

dynamic

head2

(ft)

Maximum pumped

volume at given lift in

2 hours for indicated

pump system3,4

 Pump-

 system

 suitability5,6

1 2 20 10 25 120 (Fultz SP-300) Suitable

1 2 20 10 25 144 (Keck SP-84) Suitable

1 2 20 10 25 840 (Grunfos RediFlo2)Suitable

2 4 60 118 75 96 (Fultz SP-300) Unsuitable

2 4 60 118 75 132 (Keck SP-84) Suitable

2 4 60 118 75 768 (Grunfos RediFlo2)Suitable

3 2 40 20 160 ---7 (Fultz SP-300) Unsuitable7

3 2 40 20 160 ---7 (Keck SP-84) Unsuitable7

3 2 40 20 160 538 (Grunfos RediFlo2)Suitable
19

Table 4. Example of a method to determine pump-system suitability as a function of selected well

and pump characteristics--Continued

_____________________________________________________________________________

3Maximum pumped volume is calculated using the pumping rate for a given pump system from manufacturer’s specifications at the required lift (or TDH) multiplied by an assumed purging time of 2 hours.

Example pumping rates in gallons per minute (gpm) as a function of lift (TDH) for selected pump

systems from manufacturer’s specifications. With antibacksiphon device, extension lines, and directionalcontrol flow valves that follow pump-reel system, effective pumping rate is assumed to be 80 percent of that

given by the manufacturer. Actual rates, particularly as lifts approach the limit of each system, could be less

than those specified.

4For practical reasons, and except when quality-control samples are taken, field teams aim to complete

all activities at each well within 4 to 6 hours. Thus, purge times generally need to be kept under 2 1/2 hours,

with the pumping rate during the last half hour equal to the sampling rate (no more than about one tenth of

a gallon per minute).

5Pump-system suitability is determined as follows:

Suitable if the maximum pumped volume at a given lift (or TDH) in 2 hours for the indicated pump

type is equal to or greater than the required purge volume.

Unsuitable if the maximum pumped volume at a given lift in 2 hours for the indicated pump system

is less than the required purge volume or if the required lift (or TDH) exceeds the maximum for the

pump.

6When two or more pump types meet requirements outlined above, other factors considered in pump selection include ability of pump system to be decontaminated adequately, portability, susceptibility of pump

to seizure, ease of repair and use in the field, and cost. It is assumed comparison is among pumps that are

constructed and can be operated in a manner suitable for NAWQA sampling.

7Required lift exceeds maximum lift of the pump; therefore, pump is unsuitable under conditions

given in this example.

Lift (in feet)

Pump system 0 25 50 75 100 125 150 175 200 225 250 275

Pumping rate (gpm)

Fultz Model No. SP-300 1.1 1.0 0.9 0.8 0.7 0.5 0.4 --- --- --- --- ---

Keck Model No. SP-84 1.3 1.2 1.2 1.1 1.0 0.9 0.8 --- --- --- --- ---

Grunfos Model No. Redi-Flo2 7.2 7.0 6.7 6.4 6.0 5.7 5.0 4.4 3.8 3.0 2.1 ---

Example maximum pumped volume (gal) as a function of lift for the three pump systems given above,

assuming pumping time is 2 hours.

Lift (in feet)

Pump system 0 25 50 75 100 125 150 175 200 225 250 275

 Maximum pumped volume in 2 hours (in gallons)

Fultz Model No. SP-300 132 120 108 96 84 60 48 --- --- --- --- ---

Keck Model No. SP-84 156 144 144 132 120 108 96 --- --- --- --- ---

Grunfos Model No. Redi-Flo2 864 840 804 768 720 684 600 538 456 360 252 ---
20

Regardless of the pump type chosen, the pump system (pump intake, tubing, and reel) must

meet certain requirements. The pump can be purchased without an antibacksiphon because a

suitable antibacksiphon is to be added by the Study Unit (table 3). The pump line should be solid, high-density Teflon tubing. Teflon-lined polypropylene or other tubing is not recommended

because the exterior tubing often is not as inert as Teflon. In addition, the outer tubing can separate from the Teflon lining, causing the thin-walled Teflon tubing to pinch or collapse. Suitable

pump tubing can be ordered in 50-ft segments connected with 316-stainless steel (SS-316) quick

connections, which makes it possible to use the shortest length of tubing needed for each well.

In addition, it is recommended that the reel that holds the tubing be designed to turn (while raising or lowering the pump intake and tubing), while the pump is in operation, and while the pumpreel outlet is connected to an extension line that runs to the remainder of the sample-collection

setup.

Other types of equipment (bailers, bladder pumps, peristaltic pumps) can be considered for

some site conditions, or special data-collection needs. The use of such equipment generally is

not recommended. Most alternative sample-collection devices are either limited in their lift

potential, constructed of materials that are unsuitable or difficult to decontaminate, or deliver the

sample in a manner (for example, under suction) that they cannot be used for most sites, or do

not provide data of suitable quality for all NAWQA constituents (F.D. Wilde, U.S. Geological

Survey, written commun., 1995--see footnote 1).

Study Unit staff that need to collect ground-water-quality samples using equipment other

than that specified (table 3) must discuss their plans with the NAWQA QA Specialist. At a minimum, it is expected that sufficient QC data are available, or will be collected, to verify that the

ground-water data obtained with the alternative equipment is similar in quality to data being

obtained by the NAWQA Program in general.

Field instruments

Each Study Unit is to obtain suitable field instruments to collect data for pH, specific electrical conductance (SC), dissolved oxygen (DO), and temperature (T). If samples for trace

elements (such as iron, manganese, aluminum, or uranium) are collected, sample turbidity (TU)

also is measured. These data (pH, SC, DO, T, and possibly TU) are part of the required waterquality record for each ground-water sampling site (table 1), and also serve as QC measures that

are used to assess the chemical variability of water before and at the time samples for other

chemical constituents are collected. In collecting these data, however, the field instruments used

must meet certain requirements (table 5).
21

1Slope test and temperature correction are described in Radtke and Wilde (in press).

2Use spectrophotometric or iodometric method for accurate measurements of dissolved-oxygen

concentrations less than 1 mg/L (Radtke and Wilde, in press).

Table 5. Requirements for meters and sensors used for field measurements taken at groundwater-quality sites of the National Water-Quality Assessment Program (modified from Radtke

and Wilde, in press)

[°C, degrees Celsius; mV, millivolt; ∆mv/∆pH, change in millivolts divided by change in pH at measurement temperature (in °C); ≥, greater than or equal to; μS/cm, microsiemens per centimeter at 25°C;

≤, less than or equal to; >, greater than; mg/L, milligrams per liter; NTU, nephelometric turbidity units;

NWIS-I, National Water Information System-I]

Field measurement Performance requirements

Temperature (°C)

(recommend thermistortype thermometer)

Reading to 0.1°C for temperatures from -5 to 45°C; bias within

0.2°C. (Requirement applies to any thermistors used in association with other field measurements, including those contained

in other field-measurement systems. Sampling thermal systems

can require readings and calibration to 52°C.)

pH (standard units; require

electrometric method)

and field titrations

Reading to 0.1 standard unit (or 0.05 unit for instruments that

display more than two digits to the right of the decimal). Temperature compensating; mV readout; rapid electrode response--

maximum 15- to 20-second elapsed time for reading to “lockon” the low pH calibration buffer after meter is calibrated with

high pH 7 buffer; pH electrode must pass slope-test [(∆mv/

∆pH) ≥ 0.94 x (Theoretical Nernst slope)], corrected for temperature.1

Specific electrical

conductance

(μS/cm at 25°C)

Reading within 5 percent of full scale at ≤100 μS/cm or within

3 percent of full scale at >100 μS/cm; temperature compensation range from -2 to 45°C or greater, if needed. Instrument

must compensate for temperature to provide readings at 25°C,

or temperature readings are required to apply correction factor

and report measurement at 25°C.

Dissolved oxygen2

(require amperometric

method)

Reading to 0.3 mg/L or less for concentrations ≥1 mg/L. Temperature compensation and temperature measurement required.

Field barometer needed to determine barometric pressure

correction factor.

Turbidity (recommend

nephelometric method)

Select instrument designed to provide precise and unbiased

measurements at 0 to 40 NTU. Reading within 5 percent full

scale for 1 to 500 NTU, and within 0.02 NTU for turbidity less

than 1 NTU. Turbidity entered into the NWIS-I data base must

be made using nephelometric measurements.
22

Water levels are to be determined whenever possible before other water-quality data are

collected from wells (Lapham and others, in press). The static water level within a few hundred

feet below land surface is measured using a chalked steel tape, and the measurement is repeated

until two consecutive measurements differ by no more than 0.02 ft, or until the reason for less

precise measurements is determined and documented. In addition, the depth from land surface

to the bottom of the well is measured during each site visit whenever possible to verify the integrity of the well construction.

Each field instrument must be calibrated, operated, maintained, and stored, and the necessary calibration and test results documented according to USGS protocols. The protocols for

ground-water-quality field measurements are described in Radtke and Wilde (in press).

Water-quality vehicles

Different vehicle designs will be used among Study Units because of differences in terrain,

accessibility of sites, travel distances, trip duration, and other factors. In selecting and modifying

a vehicle for water-quality data collection, however, it is recommended that safety and quality

control be given high priorities. Study Unit staff also are encouraged to research designs already

in use and to dedicate vehicle(s) solely to the collection of water-quality data.

Safety is a vital concern. The most important thing a water-quality vehicle will carry is the

field team. To protect the team, all equipment is secured and properly stored behind passenger

barriers when in transit, and without affecting the driver’s visibility. In addition, vehicle supplies

should include safety cones; safety glasses; fire extinguishers; first-aid, eye-wash, and chemicalspill kits; and Material Safety Data Sheets--all placed where they are readily accessible. If sample collection or processing occurs inside the vehicle, ventilation must be adequate and there

must be sufficient room to operate. Flex hose is used to vent combustion exhaust away from a

vehicle that is stationary with the engine running, and is stored and transported outside of the

sampling vehicle. Flammable solvents (such as methanol) and pressurized gases (such as nitrogen) are transported according to local and State regulations. Regular service and maintenance

and before-departure safety inspections of the vehicle are scheduled by the field team. If questions arise in regard to safety or inspection procedures, methods, or equipment, contact the

District safety officer.

Quality assurance of the sampling vehicle is critical to a successful investigation. This

vehicle should enable the field team to collect high-quality samples and data. Despite diverse

external conditions, the vehicle should provide a clean environment for sampling and equipment,

and a suitable environment for protecting equipment from damage during transport. The vehicle

design also should provide temporary protection of field instruments, chemical reagents, buffers,

preservatives, standards, and most water-quality samples from extreme heat and cold. It also

must provide for the temporary (and contaminant-free) storage of some samples (VOCs, pesticides, nutrients), and some reagents (for example, spike solutions for pesticides and VOCs and

VOC acid preservative) at near-freezing temperatures. If the vehicle interior is used for the collection or processing of water-quality samples, then adequate lighting, plumbing, and counter

space are needed. Sample collection and preservation chambers are used whether working inside

or outside the vehicle. These reduce contamination of and from the vehicle interior.
23

Obtain and design vehicles that can be dedicated solely to water-quality sampling. A

vehicle used for water-quality data collection is not used for the storage (even temporary) of a

generator using gasoline or other types of fume-producing fuels, or of heavily soiled equipment,

clothing, or tools. Nor should a vehicle previously used for such storage be converted to a waterquality vehicle. One might even question the adoption of a used water-quality vehicle if samples

were collected and, in particular, preserved within the vehicle without regard to possible vehicle

contamination. In each case above, there is a risk that the vehicle will be, or has been, permanently contaminated.

Storage facilities

Field vehicles are not suitable for storage of most supplies and some equipment used for

water-quality data collection. When not in operation, the vehicles cannot provide adequate protection from extreme heat or cold, which can destroy or degrade chemical standards, buffers, and

other reagents, as well as damage some field instruments. Especially during extremes in temperature, remove sensitive supplies and equipment from an idle vehicle to a safe indoor location

on a daily basis. Clean and secure facilities, which are separate from those used for other types

of NAWQA equipment (such as generators, fuel, drilling supplies and materials, and permanently soiled gear), are needed for longer periods of storage.

Timing of purchases

Durable equipment and supplies (such as vehicles, pump systems, plastic bottles) are

ordered well in advance of the first field season, and thereafter on an as-needed basis. Begin

vehicle purchase and modification(s) 12 to 14 months before the vehicle is needed for waterquality data collection. Nonperishable, and limited quantities of perishable supplies (see below)

are purchased and on hand at least 3 to 6 months before water-quality data collection begins.

Pump systems and other sample-collection equipment also can take up to several months to

obtain, assemble, and modify to complement vehicle design.

Some supplies, such as most chemical solutions, have a limited shelf life. As part of their

planning, Study Units should (1) follow manufacturer’s recommendations on storage, and (2)

query their suppliers about shelf life for any preservatives, buffers, standards, and reference samples, as well as for blank, spike, surrogate, and instrument-sensor solutions, or any other chemical reagents. This will prevent overstocking and reduce waste. Upon receiving these supplies,

the date of receipt and the expiration date should be marked clearly on time-sensitive supplies.

Study Units also are required to record supply lot numbers. Without these records, the QA and

QC information that exists for these supplies, and provided by lot number, cannot be utilized by

the Study-Unit or NAWQA National Program. This is one of the quality-assurance measures

that could be needed to correctly interpret water-quality QC data.

Study-Unit staff are likely to select the most appropriate vehicle design, pump system, and

related equipment after information from site visits is obtained, and after sampling teams have

had some training (see “Training” below). Following training, the field teams need their equipment and supplies for practice, and to verify that they are suitable for water-quality data collec-
24

tion (see “Field Evaluation” below). Therefore, most nonperishable equipment and supplies need

to be on hand at least 3 to 6 months in advance of the first field season of data collection.

Training

Modifications in USGS protocols and recommended procedures (F.D. Wilde, U.S. Geological Survey, written commun., 1995--see footnote 1), and the need for consistency dictate that

training in the collection and management of water-quality data is required for most Study-Unit

staff. This training is to be obtained through USGS Level I courses and field experience, ideally

before water-quality data collection begins (table 6).

Field Evaluation

Each Study Unit is required to test and evaluate the sample-collection equipment and procedures that commonly will be used (table 6, no. 4). This is separate from, and occurs after, the

field training with Study-Unit equipment. To avoid unnecessary delay in planned data collection

while awaiting laboratory results, this test should be conducted at least 2 months before sample

and data collection begin. Ideally, the evaluation can occur toward the end or after the field exercise devoted to equipment shakedown and cross-training (table 6, no. 3).

To conduct the test, the Study Unit selects a well with measurable concentrations of as

many of the following contaminants as possible: VOCs, pesticides, nutrients, and (if targeted for

investigation by the Study Unit) trace elements. The field team collects samples for all constituents (in the order and manner in which samples commonly are going to be collected--see “Sample Collection and Processing”). After sample collection, equipment is decontaminated. Field

blanks for all constituents are collected with the decontaminated equipment. Two field-spiked,

blank samples are prepared for the VOC schedule and for each pesticide schedule. One blank

sample for the VOC schedule is spiked by one field-team member, and its replicate is spiked by

the other field-team member. One field-team member also spikes the blank sample for one pesticide schedule; the other field-team member spikes the other blank sample for the second pesticide schedule. (Definition of QC samples is provided in “Design of Quality-Control Sampling

and Schedules.”) All ground-water-quality samples and QC samples are sent to the NWQL for

analysis.

Data from the ground-water-quality and QC samples are evaluated by the Study Unit, and

the evaluation and data are forwarded as soon as possible to the National Program (NAWQA QA

Specialist). These data are to confirm that (1) the ground water contained measurable levels of

some contaminants, (2) decontamination procedures removed contaminants from equipment, and

(3) the procedures used to prepare spiked blanks led to acceptable recoveries of selected VOCs

and pesticides.

The evaluation assures the field team, Study Unit, and National Program that the protocols

and procedures are satisfactory. Potential problems identified by the Study Unit(s) are corrected

before sample and data collection begins.
25

Table 6. Recommended sequence of training-related activities to prepare for National WaterQuality Assessment (NAWQA) Program ground-water-quality data collection

[USGS, U.S. Geological Survey; QC, quality control; NWQL, National Water Quality Laboratory]

______________________________________________________________________________

1. Determine data-collection and management training needs.

•Review protocols and recommended procedures (this report).

•Review National Field Manual (Radtke and Wilde, in press).

•Incorporate possible modifications to above (commonly described in NAWQA or USGS

internal memorandums).

2. Train field team(s) and data-management personnel accordingly and formally.

•Through USGS Level I and higher level training courses.1 Field Water-Quality Methods

for Ground Water and Surface Water (G0282) currently is required for at least one

member of each team placed in field for data collection. It is recommended that at least one

member of the Study-Unit staff attend the course Quality-Control and Sample Design and

Interpretation (GO342). (A field team is assumed to consist of two people.)

•Take data-collection and QC training courses early, ideally in the fiscal year before intensive

 data collection begins.

3. Enhance and reinforce formal training.2

•New field team(s) can accompany or temporarily employ experienced (mentor) teams

from another Study Unit that is completing data collection in the fiscal year before

the new team will begin data collection. Select mentors on the basis of similarities in

types of wells, terrain, equipment, and other factors that the two Study Units have in common.

•New field team(s) should practice data collection with equipment that will be used, and

alternate activities to ensure each team member is cross-trained in all aspects of data collection.

4. Evaluate data-collection protocols, recommended procedures, and equipment.3

•Conduct data collection at a contaminated well at least 2 months before any water-quality

data collection begins. Include field blanks and field-spiked source-solution blanks. Submit

ground-water-quality and all QC samples to NWQL for analysis.

•Evaluate and share results with the National Program. (See text for further discussion).

______________________________________________________________________________

1The Level I course provides individual training in ground-water-quality and surface-water-quality

data-collection protocols and procedures that include those for the National Water-Quality Assessment

Program. Other courses can be taken that cover data management and analysis, such as that recommended

for QC.

2Because modifications to protocols and recommended procedures are likely to occur, training without

taking the formal course currently is not considered an acceptable substitute for all members of a field team.

3See discussion in section entitled “Field Evaluation.”
26

Design of Ground-Water-Quality Sampling Schedules

As part of planning for field sampling, schedules are prepared annually or more frequently,

if needed, for the collection of ground-water-quality and QC data for each ground-water component (Study-Unit Survey, Land-Use Study or Flowpath Study) targeted for investigation each

year. These schedules list the daily activities for the field team, data managers, and support staff.

For ground-water-quality samples, the schedule describes the timing and order in which

wells for each ground-water component are targeted for data collection (table 7). General scheduling considerations include component factors, travel times, personnel requirements, and site

conditions (table 8). Each schedule is designed over a period of several months, and before any

ground-water-quality samples are collected.

Study Units will pay particular attention to factors that enhance the consistency and quality

of samples and data obtained and provide the Study Unit and National Program with the necessary data to determine the quality and suitability of data collected for NAWQA assessments

(table 9). The design and scheduling of QC data collection, which are critical and integral parts

of water-quality data and data collection (Shampine and others, 1992), are discussed in detail in

the next section. For most of the other factors (tables 8 and 9), it is assumed that the information

needed is obtained through staff planning meetings and site visits conducted before data collection begins.

As a general rule, except for Flowpath Studies, most Study Units will find that a single,

two-person field team often needs a day to conduct data-collection activities at one well. With

experience, and under the optimum field conditions, some teams will be able to collect data from

more than one well per day. In the case of Flowpath Studies, the close proximity and shallow

depths of wells also could permit sampling at more than one well per day. In addition, wells

targeted for QC data collection could require an additional team member to complete activities

in a single day.
27

Table 7. Example of a sampling schedule for a 28-well Land-Use Study

[Assumes (a) one (two-person) field team generally collects samples on a weekly run (Monday-Thursday);

(b) incorporation of general scheduling considers component factors, travel times, personnel, and site

conditions (table 8), as well as requirements to enhance data quality (table 9); and (c) routine quality-control

sampling occurs at selected wells distributed throughout the collection period (third person possibly joins

team). SRS, standard reference samples for trace elements; VOC, volatile organic compound]

____________________________________________________________________________________________

Period of activity Activity to be conducted by team

____________________________________________________________________________________________

Week 1 Day 1 (M) Depart for Well 1: collect ground-water (GW) samples.

 2 (T) Well 2: Collect GW and quality-control (QC) samples.

 3 (W) Well 3: Collect GW samples.

 4 (Th) Well 4: Collect GW samples, return to office, unload vehicle.

 5 (F) Evaluation and preparation: Study Unit reviews progress, plans, sampling

schedule, and completes final preparations for following week’s activities.

Week 2 Days 8-12 Wells 5-8: Similar schedule as week 1, but without QC data collection.

Week 3 Day 15 (M) Well 2: Review QC data and continue sampling if no problems appear;

decision to sample two wells per day when possible is made.

 16 (T) Team and staff complete preparations, team departs office.

 17 (W) Well 9: Collect GW and QC samples (including one SRS).

 18 (Th) Wells 10 and 11: Collect GW samples.

 19 (F) Team returns to office and, aided by staff, unloads and cleans vehicle.

Week 4 Days 22-26 Wells 12-15: Similar to schedule for week 2.

Week 5 Day 29 (M) Well 9: Review QC data and continue sampling if no problems appear.

Team, aided by staff, completes preparations, and departs office.

 30 (T) Wells 16 and 17: Collect GW samples.

 31 (W) Well 18: Collect GW samples.

 32 (Th) Well 19: Collect GW and QC samples (with VOC trip blank, as planned);

team returns to office late in day.

 33 (F) Team and staff unload, clean, and restock vehicle.

Week 6 Days 36-40 Wells 20-23: Similar to schedule for week 2.

Week 7 Day 43 (M) Well 24: Team departs office, collects GW samples.

 44 (T) Well 25: Collect GW samples.

 45 (W) Wells 26 and 27: Collect GW samples.

 46 (Th) Well 28: Collect GW and QC samples, team returns to office

and with staff unloads and cleans vehicle.

 47 (F) Vehicle goes in for regular service and maintenance.

Week 8 Day 50 (M) Team and staff receive QC data (wells 19 and 28). If QC data are

satisfactory, sample collection continues unabated. Team and

staff prepare for next component to be sampled. Remaining two

SRS samples needed for the year will be included in data collection

for the next component. _____________________________________________________________________________________________
28

Table 8. Basic considerations in designing annual ground-water-quality sampling schedules for

Study-Unit components (Land-Use Studies, Study-Unit or Subunit Surveys, and Flowpath

Studies) of the National Water-Quality Assessment Program

______________________________________________________________________________

1. Component factors

• Number of each type of component.

• Number of wells per component.

2. Travel times

• Between office and wells.

• Between wells.

• Between well and overnight shipping sites.

3. Personnel

• Number of field teams.

• Number of individuals per team (generally consider two members; possibly third person

 at wells that include QC sample collection).

• Experience of personnel in team.

• Office staff support.

4. Site and seasonal conditions

• Equipment setup time (water-supply or monitoring well).

• Purge time.

• Data-collection requirements (ground-water quality only or ground-water quality

 and quality control).

• Duration of field season.

______________________________________________________________________________
29

Table 9. Requirements for the design of National Water-Quality Assessment Program groundwater-quality sampling schedules to enhance data quality

[QA, quality assurance; QC, quality control; VOC, volatile organic compound; NWQL, National Water

Quality Laboratory; μg/L, micrograms per liter] ____________________________________________________________________________________

1. Schedule to avoid seasonal or other problems in data used for spatial analysis

• Except for Flowpath Studies, collect all samples for all components in shallow-depth wells

between late spring and early fall if those samples include seasonally-applied chemicals.1

• Except as noted below, complete sampling for a given component in the shortest time possible,

and before the same field team begins data-collection at another component.

2. Integrate quality-assurance and quality-control (QA and QC) data collection into each

component schedule

• Conduct QA procedures and collect QC data at selected sites in each component throughout

the period of water-quality data collection.

3. Set reasonable performance levels; initially, collect samples at one well per day for Land-Use Studies

 (or Study-Unit Survey) so that:

• With time and experience, the long-term average could approach two wells per day.

• Wells selected for QC data collection typically will require a full day and possibly an additional

person.

• Sampling at more than two wells per day could be possible, particularly for Flowpath Studies

(shallow-depth wells in close proximity).

4. Avoid over-specialization; schedule frequent rotation of duties among the field-team members

• Prepare for unexpected absences to prevent a halt in sampling, or the collection of potentially

poor-quality data.

5. Schedule data collection at wells known or suspected of having high (greater than 10 μg/L) VOC or

pesticide concentrations near the end of the data-collection period to avoid cross-contamination of

other wells or samples

• Take additional field blanks to check that equipment is decontaminated before the same equipment is

used at another well.

• Notify NWQL (on Analytical Service Request form--comment to laboratory line) if it is known or

suspected that VOC or pesticide concentrations are expected to exceed 10 μg/L.

6. Plan for resampling, regardless of whether or not it can be anticipated

• Despite the best planning, teams sometimes find they are inadequately equipped for data collection..

• Data-quality reviews could indicate resampling is necessary.

• Resampling is recommended near the end of the fiscal year (first week in September).

7. Provide time for data review, schedule revision, and equipment maintenance, if the component

consists of 20 or more wells, which generally will require 2 or more months to sample

• With intermittent periods (day or two in length) of no data collection.

• To review progress, make scheduled revisions, and discuss QC data.

• To restock, maintain, repair, or replace equipment and supplies.

8. Schedule data collection to avoid exceeding sample-holding time, which begins when the sample

is collected, and ends with sample analysis

• Holding times for water samples of radon, nutrients, pesticides, and VOCs are the shortest--3, 5, 7,

and 14 days, respectively.

• From late spring to early fall (the peak analysis period) at least half the holding time can expire

after samples are logged in at the NWQL.

• Because radon has a short half-life (3.6 days), samples for this element should not be collected

on a Friday, unless they can reach the NWQL by noon on that Friday.

_____________________________________________________________________________________ 1

Pesticide concentrations measured in ground water nationwide appear higher and more uniform throughout

this period than the concentrations measured from late fall to early spring (J.E. Barbash and E.A. Resek, in prep.,

Pesticides in Ground Water; Distribution, Trends, and Governing Factors: Ann Arbor Press, Chelsea, Mich.).
30

Design of Quality-Control Sampling and Schedules

Each Study Unit is required to collect similar types of QC samples (table 10). Those that

are collected regularly throughout each field season are referred to as “routine QC samples.”

Additional QC samples, referred to as “topical QC samples,” occasionally could be collected by

some or all Study Units to isolate and resolve problems or evaluate modifications to NAWQA

field methods.

The data obtained from routine or topical QC sampling are used to estimate the potential

bias (either from contamination or in recovery) and measurement variability for selected analytes. Routine QC samples provide the data required by the NAWQA Program to make general

inferences about bias and variability for all water-quality data collected. Bias and variability

measurements from routine QC samples reflect combined field and laboratory errors that occur

during data collection. Measurements obtained from topical QC sampling will reflect errors

associated with a specific field or laboratory procedure employed by NAWQA and targeted for

study.

Study Units can use QC data in several ways. Those that can derive bias and variability

estimates from routine QC sampling in a timely manner can use the results not only to assess the

quality of data being collected, but also, in some cases, to identify wells that need to be resampled

(Koterba and others, 1991). In the case of topical QC data, sources of sample contamination or

bias that occur as a result of sample collection and processing, initially identified through routine

QC sampling, can be isolated and eliminated (Rea, in press; Koterba and others, 1991).

Bias and variability estimates also can be used during data analysis and interpretation of

ground-water-quality data. For each ground-water component, the magnitude of these error estimates provide an indication of the quality of ground-water data collected (Koterba and others,

1991 and 1993). In addition, as water-quality data from different Land-Use Studies or Subunit

Surveys are compared, contrasted, or combined, the corresponding routine estimates of bias and

variability from QC data also can be compared, contrasted, and combined to make inferences

about the quality and suitability of the aggregated water-quality data that are being used for

Study-Unit or National Assessments.

In some cases, data analysis and interpretation can depend on the timely analysis of routine

and topical QC data obtained in the field combined with timely discussion of these data with the

National Program and the NWQL. Examples of the above, which led to modifications in StudyUnit field methods and in the QC sampling design, and ultimately improved data quality, analysis, and interpretation include studies by Ferree and others (1992) and Koterba and others (1994).

Their experience indicates how critical it is for Study-Unit plans to remain flexible. These plans

must allow for the possible modification of the initial designs for routine QC sampling (as described below), or the methods used to collect these and ground-water-quality samples (described later in this report). Such modification could prove critical to correctly identifying the

occurrence and distribution of contaminants in ground water and their relation to Study-Unit

landscape and subsurface features.
31

Table 10. Quality-control samples for ground-water components of the National

Water-Quality Assessment (NAWQA) Program

[Definitions are consistent with those of the U.S. Geological Survey Branch of Technical Development and Quality Systems (BTD&QS) and the Office of Water Quality. NWQL, National Water

Quality Laboratory; VOCs, volatile organic compounds]

 Sample type Description Purpose

1. Blanks1 Types include field, sourcesolution, and trip.

Assess bias from contamination of

blank water.

•Field Blank water passed through

equipment in the field, and collected in a manner similar to that

used to collect water-quality

data, but after equipment is used

and decontaminated.

Verify that decontamination procedures are adequate, and that field

and laboratory protocols and recommended procedures do not

contaminate samples.

•Source solution2 Blank water placed directly in the

sample container, but in a clean

environment.

Verify that blank water is contaminant-free just before it is used for a

field blank.

•Trip Blank water placed in sample

container by NWQL, shipped to

study with empty containers, and

returned unopened by Study Unit

from field for analysis.

Verify that shipping, handling, and

intermittent storage of containers

does not result in contamination or

cross-contamination of samples.

2. Replicates3 Two or more ground-waterquality samples collected sequentially for the same analytes.

Assess combined effects of field

and laboratory procedures on

measurement variability.

3. Field spikes4 Types include samples prepared

from blank water or from ground

water.

Assess recovery bias of analytes in

spike solution.

•Source-solution

water5

Two source-solution blanks to

which identical volumes of spike

solution are added, but by different members of field team. For

VOCs, preserve with NWQL

acid before spiking.

Verify equipment and procedures

for field spiking, handling, shipping, and analysis lead to similar

results among Study Units.

•Ground water Two or more replicate groundwater-quality samples to which

identical volumes of spike solution are added in a manner that

does not substantially alter sample matrix. For VOCs, preserve

with NWQL acid before spiking.

Assess recovery bias and variability in relation to different groundwater matrices.
32

1Blank water is certified by supplier as free of analytes of interest at concentrations that

exceed NAWQA detection or reporting level. A trip blank is only required for VOCs.

2Because blank solutions are not regularly analyzed for dissolved organic carbon (DOC),

source-solution blanks are required along with field blanks for this analyte. A source-solution blank

for DOC is required each time a field blank for DOC is taken.

3Chemical composition of water entering the well and being collected is assumed constant

during time needed to collect sequential samples (including replicates).

4Spike solutions for NAWQA contain either selected VOC or pesticide analytes; solutions

are obtained and used in accordance with instructions from the NWQL. At least one unspiked

(background) ground-water sample from the same well used to obtain the samples for field

spikes is analyzed in conjunction with field-spiked samples (see text).

5Preserved and spiked source-solution blanks for pesticides and VOCs are prepared only

as part of the initial evaluation of equipment and procedures before data collection begins.

Sample type Description Purpose

4. Standard

 reference

 (mixtures)

Prepared by BTD&QS as mixtures, sent to Study Units collecting trace-element samples,

shipped unopened from field to

NWQL for analysis.

Assess recovery bias and

variability of selected trace

elements.

Table 10. Quality-control samples for ground-water components of the National

Water-Quality Assessment (NAWQA) Program--Continued
33

Routine quality-control samples: type, number, site selection, and timing

The current NAWQA QC sampling design for ground water is based on the integrated approach described by Shampine and others (1992). Under this design, it is recommended that each

Study Unit follow similar procedures (tables 11 and 12) to identify (1) the types of routine QC

samples collected, (2) the wells at which these samples will be obtained, and (3) the timing of

QC sample collection for each of the ground-water components scheduled for data collection in

each field season. These procedures ensure that the data obtained for each routine QC sample

type (1) represent major differences in the major ion chemistry (sample matrix) of ground water

targeted for study, (2) are suitable for estimating measurement bias and variability for the analytes of interest, and (3) reflect possible temporal variations in field and laboratory methods during the time period that ground-water-quality data are collected (table 13).

It would be ideal in terms of planning, efficiency in the field, and costs if similar routine

QC designs could be used for all ground-water components. Because Land-Use Studies, StudyUnit (or Subunit) Surveys, and Flowpath Studies differ in their design and scope, the types and

numbers of routine QC samples, the wells selected for collecting these samples, and the timing of

visits to the wells selected will differ somewhat among these components.

It would be ideal in terms of planning, efficiency, and costs if all routine QC samples could

be collected at the same well sites for each ground-water component. Representative and suitable QC data, however, often can only be obtained by scheduling the collection of different types

of routine QC samples at different wells within a given component (see below), or, in the case of

the VOC trip blank and (possibly) trace-element standard reference samples, at wells selected

from among several components sampled in the same field season (table 13, footnote 1).

Land-Use Studies. A typical Land-Use Study is focused primarily on one major land-use

classification, and for ground water, involves the collection of samples for a variety of analytes

(table 1) from each of a relatively small number of wells (about 30, including reference wells)

completed at shallow depths and often in a single aquifer. Therefore, a typical design for routine

QC data collection requires the collection of many different QC sample types to cover the variety

of analytes being investigated (table 12). It also requires a minimal number of samples for each

QC-sample type because differences in the quality of ground water among wells are assumed to

reflect chiefly the intensity of a single land use on the shallow part a single aquifer.

Some wells in the Land-Use Study will need to be chosen (if possible, and according to

methods described later in this section) specifically to collect the required number of routine, replicate ground-water samples and routine field blanks (table 13). These wells are chosen, in part,

because they are likely to provide samples with measurable (greater-than-method-reportinglevel) concentrations. (Estimating the variability of measurements for a given analyte using

replicate samples requires that these samples contain measurable, greater-than- or equal-tomethod reporting-level concentrations for that analyte.) They also are selected, if possible, to

provide a range in measurable concentrations that reflect the effects of that land use on shallow

ground-water quality.
34

Table 11. Procedures to identify the type and schedule the annual collection of routine qualitycontrol data for ground-water components of the National Water-Quality Assessment Program

_____________________________________________________________________________

1. Identify analyte groups for which water-quality data will be collected that field season

• On the basis of national requirements (table 1).

• To which are added local Study-Unit interests, such as trace elements.

2. Identify routine quality-control (QC) data to be collected

• On the basis of the Study-Unit component (for example, see table 12).

• Determine QC sample types by analyte group to be collected.

• Determine number (or frequency) of each type to be collected.

3. Identify wells and develop schedules for routine QC data collection for each

component1

• Select wells to provide suitable and representative QC data (see text and table 13).

• Schedule visits to these wells to provide QC data collection for each analyte group

throughout the months that water-quality data for that analyte group and component

are being collected (see text and table 13).

_____________________________________________________________________________

1If volatile-organic-compound (VOC) and trace-element samples are collected during a given

field season, then at least one VOC trip blank, in addition to field blanks and spiked replicate samples,

and at least three trace-element standard-reference samples are sent from the field to the National

Water Quality Laboratory for analysis.
35

Table 12. Required type and minimum number (or frequency) of routine quality-control

samples for a Land-Use Study of the National Water-Quality Assessment Program

[Field blanks and field-spiked, source-solution blanks taken during the evaluation of methods are not included

below. Assume study consists of 25 to 30 wells. Trace-element field blanks use National Water Quality Laboratory

(NWQL) Schedule SC172 with selenium (LC0087) and arsenic (LC0112). All other routine quality-control samples

use the same NWQL schedule or laboratory code used for the corresponding water-quality samples. DOC, dissolved

(filtered) organic carbon; ALK, alkalinity (field-titration, filtered ground-water sample); and ANC, acid-neutralizing capacity (field titration, unfiltered ground-water sample; VOCs, volatile organic compounds]

_____________________________________________________________________________________________

Routine quality-control

Analyte groupa sample type Required number (frequency)

_____________________________________________________________________________________________

1. Commonly present in Field blanks Minimally at 2, but preferably

measurable concentrations: at 3, well sites.

major ions, nutrients, and

DOC. (ALK and ANC-- Source-solution blanks (Every time a DOC field blank

replicates only) is taken, only for DOC.)

Replicate (2) ground- Minimally from 2, but preferwater samples per well ably from 3 wells at different

sites.

2. Commonly present in

measurable concentrations

in some, but usually not all,

areas:

• Pesticides or VOCs Field blanks Minimally at 2, but preferably

at 3, well sites.

Trip blank (One per field season, only for

VOCs.)

Field-spiked, replicate Minimally at 2 well sites.

(2) samples per well

• Trace elements (such as Field blanks Minimally at 3 to 5 well sites.c

NWQL SC2703)b

Standard-reference- (Three per field season.)

sample mixtures

Replicate (2) ground- Minimally from 3 to 5 wells

samples per well at different sites.

• Radionuclides (such as Replicate (2) ground- Minimally from 3 wells at

radon) samples per well different sites.

____________________________________________________________________________________________ a

For tritium, deuterium-oxygen isotopes, or chlorofluorocarbons, contact a National Water-Quality

Assessment Program Quality-Assurance Specialist.

bThrough 1995, some Study Units collected and temporarily archived water-quality and quality-control

samples.

c

If trace-element concentrations of interest are low (less than 10 μg/L), collect the maximum number of

field blanks, and the minimum number of replicate sample sets specified. For high concentrations, collect the

minimum number of field blanks, and maximum number of replicate sample sets.
36

Table 13. Well- and site-selection criteria for routine quality-control samples collected for

ground-water components of the National Water-Quality Assessment Program

[Field blanks and field-spiked, source-solution blanks taken during the evaluation of data-collection methods

are not considered below. DOC, dissolved (filtered) organic carbon; VOC, volatile organic compounds; NWQL,

National Water Quality Laboratory]

____________________________________________________________________________________________

Well (site) selection criteria for Study-Unit (or Subunit) Survey,

Routine QC sample type or Land-Use or Flowpath Study ground-water components

____________________________________________________________________________________________

Field blanks (all analytes, Select wells where it is known or suspected that ground water (1) at

except radon) each well contains measurable (greater-than-method-reporting-level)

concentrations of most to all analytes and (2) collectively, for the wells

chosen, reflects some of the diversity in ground-water-quality conditions (range in concentrations for these analytes) for which the groundwater component is designed.a

Source-solution blanks Use the same well sites selected for DOC field blanks (above) for

(DOC) each component.

Trip blank (VOC) Sent from one randomly selected well site from among all well sites

for all components at which VOC samples are collected during the

same field season.

Replicate ground-water samples Use the same wells selected for field blanks (above) for each

(inorganic analytes, radio- component.a

nuclides (radon), and DOC)

Field-spiked, replicate, Select wells where it is known or suspected that ground water at each

ground-water samples well (1) contains measurable concentrations of inorganic analytes and

(VOC and pesticides) DOC (similar to those found at routine QC sites selected for field

blanks and replicate ground-water samples), but (2) do not contain

measurable concentrations of those VOCs or pesticides found in

NAWQA-NWQL spike solutions and of interest to the Study Unit for

each component.a

Standard-reference Sent from 3 well sites selected from among all well sites for all

samples (trace elements) components at which trace-element samples are collected during the

same field season.a

____________________________________________________________________________________________

a

Schedule data collection for selected wells so that water-quality and routine QC samples are obtained from

at least one of these wells early, at least another of these wells mid-way through, and at least at still another

of these wells near the end of the entire time period during which water-quality data that relate to the type of

QC sample type specified are being collected for the component or, in the case of trace-element standard

reference samples, for the field season.
37

Field blanks are collected at the same wells used to obtain replicate ground-water samples;

namely, at wells likely to have measurable concentrations of analytes in ground water. This

makes it possible to verify that (1) the sampling equipment was exposed to measurable concentrations of contaminants, and (2) equipment decontamination procedures were effective. (The

latter cannot be verified if the wells selected for field blanks contain no measurable contaminants.)

Additional Land-Use Study wells that differ from those selected for replicate ground-water

samples and field blanks need to be selected for VOC and pesticide field-spiked samples. Criteria

for selection of wells for spiked samples (table 13) ensure that the QC data are representative--

reflect the type(s) of ground water in the Land-Use Study area where VOC or pesticide contaminants are found but that unspiked samples do not contain the VOCs or pesticides of interest. This

means that recovery estimates from spiked samples (in which the analytes of interest have been

added in the spike solution) are likely to reflect recoveries from ground-water samples that contain these same analytes in similar concentrations.

The criteria also ensure that the field-spiked QC data are suitable--reflect recoveries that are

unbiased. Samples that contain measurable concentrations of pesticides or VOCs--in excess of a

few tenths of a microgram per liter--and that are spiked with similar VOCs or pesticides in accordance with current NWQL protocols generally will provide recovery estimates that have a

positive bias. The bias results because the recovery generally is calculated on the basis of the

measured concentration divided by the theoretical concentration of the spiked sample, where the

latter is estimated from the amount of analyte added in the spike solution. Recovery estimates

cannot be determined precisely by correcting for the background (unspiked) sample concentration, unless at least triplicate unspiked, and triplicate spiked, samples are collected.

The scheduling (timing) of routine QC data collection for the Land-Use Study is determined

after the wells for routine QC data collection have been selected. This involves scheduling site

visits at these wells such that routine QC data are obtained early, about mid-way through, and

near the end of the 1- to 3-month period it commonly takes to complete data collection for a LandUse Study. This implies that the ground-water sampling schedule for a Land-Use Study, or any

other ground-water component, cannot be finalized until the routine QC sampling design is developed (table 7).

Study-Unit (or Subunit) Surveys. A typical Study-Unit Survey is designed to obtain

occurrence and distribution data on a variety of analytes (table 1). In this respect, a Study-Unit

Survey is somewhat similar to a Land-Use Study. A Study-Unit Survey differs from a Land-Use

Study in some respects, which affects the routine QC design.

A Study-Unit Survey can involve data collection from as many as 100 to 120 wells associated with multiple, rather than one, land use. These wells also often will be distributed among

several Subunit Surveys, each consisting of about 30 wells. The 30 wells in each Subunit Survey

often will be completed in shallow and deep parts of one or more aquifers. Thus, wells in a subunit generally will reflect a greater diversity in land-use and water-quality conditions than that

associated with a single Land-Use Study. Overall, data collection from these Subunit Surveys

collectively will take more time to complete than it will take to complete a single Land-Use

Study.
38

Because Study-Unit or Subunit Surveys and Land-Use Studies often will involve the collection of similar types of ground-water-quality data, the types of routine QC samples required

for a survey for each analyte are similar to those required for a Land-Use Study (table 12). The

minimum number of each type of QC sample required for each Subunit Survey is at least the

same number as that required for a Land-Use Study. Because of the potential for a greater diversity in landscape and subsurface conditions in Subunit Surveys compared to Land-Use Studies, however, it is recommended that at least one or two additional sites be selected for replicate

ground-water samples for the inorganic analytes (major ions, nutrients, alkalinity, acid neutralizing capacity, dissolved organic carbon, and possibly trace elements) and the field blanks in

each Subunit Survey.

If the Study-Unit Survey is designed as a single entity (not conducted using Subunit Surveys), then the minimum number of QC samples required for each sample type for the survey is

increased in direct proportion to the number required for a Land-Use Study (table 12) on the basis

of the total number of wells being sampled for the survey divided by the total number of wells

being sampled for a Land-Use Study (which for the purposes of this calculation is taken as 25).

Thus, a survey that involves 50 wells requires twice the minimum number of each type of QC

sample than generally is required for a Land-Use Study.

Survey wells are selected for routine QC samples and scheduled for data collection using

the same approach outlined above for a Land-Use Study. Different wells are selected for the different types of QC samples to provide QC data that are representative of differences in water

quality, suitable for providing estimates of measurement bias, variability, and recovery, and cover the time period during which the Survey ground-water-quality data are collected (table 13).

Flowpath Studies. A typical Flowpath Study will assess spatial differences and possibly

temporal variability in each of a selected number of analytes among wells located in different

parts of a local ground-water flow system. The number of wells used for water-quality data collection commonly will be less than 20, with most wells completed in a single aquifer that underlies a single land use.

The routine QC design for a Flowpath Study involves the selection of routine QC sample

types (as described in table 12) that relate to only those analytes that are targeted for investigation

by the Study Unit. These routine QC sample types are to be collected at selected sites the first

time the flowpath wells are sampled and, thereafter, at sites and times that reflect Flowpath Study

objectives--such as evaluating spatial or temporal differences in analyte concentrations. As a

general rule, the sites selected and frequency of routine QC sample collection are to be sufficient

to establish that possible spatial differences or temporal trends in analyte concentrations at, or

among, flowpath wells are not primarily a function of measurement bias or variability that result

from field and laboratory methods.

Nested Studies. Ideally, the ground-water design for a Study Unit calls for Flowpath Studies to be located in selected Land-Use Study areas, and that each Land-Use Study be located in

a (Subunit) Survey area. Theoretically, this implies that routine QC data collected for one component could serve as routine QC data for another component. Ideally, this also is efficient in

terms of planning, field work, and costs. Use of this approach, however, requires the routine QC

design requirements be met for each individual component.
39

To ensure that routine QC data from one component are valid routine QC data for another

component, one component must be geographically nested within the other. That is, at least one

well must be part of both components--the well that will be used to obtain the QC data common

to both components. Data collection for both components must overlap in time, and occur at the

well targeted to provide the required ground-water and routine QC data needed for both components during that period of data-collection overlap.

Example of routine quality-control design: a case study

Regardless of the ground-water component, the design, and in particular, selection of sites

for routine QC data collection commonly will be determined using limited information. In particular, to obtain representative QC data, the wells selected are to reflect the diversity of waterquality conditions likely to be found among the wells used to collect ground-water data in each

component. In a number of cases, however, the quality of ground water in terms of analyte concentrations at each well will not be known until after NAWQA data are collected.

When water-quality data are lacking, other types of data are used to make inferences about

the likely quality of water at each well. Useful ancillary data include (1) water-quality data from

nearby wells (retrospective data), (2) data on surface features (such as land use, crop types, and

associated chemical use) from site visits and published data, and (3) data on subsurface features

(such as lithology and well depth) which are obtained during well selection (or installation) and

from published data on aquifer characteristics.

An inferential approach to identify and evaluate routine QC-sample data-collection sites

and data was employed in the Delmarva Peninsula pilot NAWQA study. In this study, Hamilton

and others (1992) used retrospective water-quality data (primarily major cations and anions) to

describe spatial and depth-related differences in ground water throughout the Study Unit, and to

identify agriculturally-affected ground water as well as unaffected (or natural) types of ground

water in the study area (fig. 1-A, encircled regions). To design QC sampling for this Study-Unit

Survey, Koterba and others (1991) used the above information along with data on surface features (general land use, and different agricultural activities such as crop type and related liming,

and fertilizer and pesticide use) and subsurface features (well depth and aquifer lithology) at each

well to select those for replicate routine QC samples (except those for field spikes) and some

field blanks. The combined ancillary data described above indicated that different types of

ground water were likely to be encountered (fig. 1-A), and that most analytes (major ions, nutrients, organic carbon, trace elements, and perhaps pesticides) were likely to be found at detectable

(above detection level, but less than reporting level) or higher concentrations at the selected

wells.

Additional wells for QC data collection were selected that reflected a diversity in groundwater types, but where it was initially inferred that pesticides found in NAWQA spike solutions

and of interest to the Delmarva Peninsula Study-Unit staff (primarily triazines and acetanilides)

were not likely to be found in samples from this second set of wells. These wells were used to

obtain samples for pesticide field spikes.
40

Figure 1. Distribution of wells selected for pesticide spikes in relation to the major-ion composition of

(A) natural and agriculturally-affected ground waters, and (B) ground-water samples in which pesticides

were detected in the Delmarva Peninsula (Koterba and others, 1993).

A

Na + K

60

80

60

20

0

100

80

40

20

0

40

20

60

80

60

20

40

80

100

HCO 3

SO 4+Cl

Ca + Mg

40

60

80

60

20

0

100

80

40

20

0

40

20

60

80

60

20

40

80

100

HCO 3

SO 4

+Cl

Na + K

Ca + Mg

EXPLANATION

Ground-water samples in which

pesticides were detected

Pesticide-spiked ground-water

samples

Natural ground waters in study area

Agriculturally-affected ground waters

in study area

B

(Axes are in percent for concentrations 
41

As water-quality samples and data were obtained by the Delmarva Study Unit, the majorion data were plotted, including data from those wells selected for routine QC sampling. In general, plots illustrated that the different types of ground water described by Hamilton and others

(1992) were being collected, and in particular, that the sites chosen for QC data collection also

reflected most of the different types of ground water found in the Study-Unit Survey area (fig.

A1, plotted points). Thus, the QC data were considered representative of the types of groundwater quality found in the study area.

Another key element addressed by the staff of the Delmarva Peninsula Study was to assess

the suitability of replicate ground-water sample or field-spiked ground-water sample QC data to

provide estimates of the method (field and laboratory) variability in concentration measurements

or method bias in recovery, respectively, for selected analytes. This was done in part by using

field-blank and unspiked (background) concentration data. In the Delmarva Peninsula Study,

field blanks (12) were collected at different sites and times, and in each case, after equipment

was contaminated (as later verified by the ground-water samples collected), and then field decontamination procedures were conducted. Blank data provided no evidence that samples

(ground-water or other QC, including replicate or field-spiked samples) were subject to contamination in the field (by ambient conditions or equipment cross-contamination) or thereafter (during handling, shipping, and laboratory analysis). Further evidence that the QC data from fieldspiked samples was suitable also came from the corresponding unspiked ground-water samples.

Of 21 wells selected for field-spiked samples, only one yielded an unspiked sample that had a

measurable concentration for any of the pesticides of interest. Thus, on the basis of field-blank

and background-sample concentration data, it was demonstrated that there was: (1) no evidence

samples of any type were contaminated during or after their collection, (2) that field decontamination procedures were adequate, and (3) that replicate and field-spiked data were not compromised by ambient or cross-contamination, and were suitable for estimating, in an unbiased

manner, the method variability in concentration measurements and the method bias in recovery

for selected analytes.

Additional data plots (for example, fig. 1-B) were constructed to illustrate that the wells

chosen for pesticide field spikes generally reflected the types of ground water in which these

same pesticides appeared as a result of what was considered normal pesticide use in the StudyUnit Survey area. Thus, it was argued that field-spiked sample data were representative of the

types of ground water in which pesticides sometimes were found.

In terms of estimating pesticide recovery and measurement variability, only one of the 21

wells chosen by the Delmarva Peninsula Study-Unit staff for field spikes yielded a background

sample with measurable concentrations of some of the pesticides found in NAWQA spike solutions and of interest to the Study Unit. This implied that, except for the data from that one well,

the field-spiked sample data were suitable for obtaining unbiased recovery and variability estimates for those pesticides of primary interest to the Study Unit. Thus, for most of the pesticide

analytes in question, recovery and measurement variability estimates were obtained using spiked

samples from all 21 wells (Koterba and others, 1993). In the case of the one analyte found in the

background sample from one well, the data from only 20 wells was used to estimate recovery

and measurement variability.
42

The preceding discussion offers one approach that made it possible to select wells and design ground-water and routine QC sampling schedules each year to provide representative and

suitable QC data for a 100-well Study-Unit Survey, which took 2 years to complete sample collection. Although the example above is for a Study-Unit Survey, the approach also is applicable

to Land-Use and Flowpath Studies.

The above approach also illustrates how a Study Unit can graphically demonstrate that the

wells selected for routine QC data collection represent different types of ground-water quality

found in a component study area. If this visual analysis of QC data is made in a timely manner

(before ground-water sampling for a component is complete), it is possible to incorporate wells

not yet sampled, or initially selected, into the routine QC design to improve the representative

nature of the QC data.

Topical quality-control samples

Field and laboratory equipment and methods for the collection of ground-water-quality

data, including those for QC, could be modified as a result of routine QC data analysis, shifts in

National Program priorities, or results from other studies. Modifications will be designed and

implemented in a systematic manner, preceded by a NAWQA memorandum that explains the

nature of the modification, the reason for the modification, and the manner in which the modification will be documented and evaluated. As part of this modification process, which is considered topical in nature, Study-Unit participation could be requested by the National Program. On

some occasions, this could require additional QC samples be collected by some or all Study

Units.

Individual Study Units could find additional QC samples are necessary to address a topic

of local concern. For example, additional field and trip blanks could be required to verify that

VOC contaminants are in the ground water, and are not being introduced during and after sample

collection (Rea, in press). In other cases, additional blanks and spiked samples could be required

to correctly assess method-related problems (Koterba and others, 1994).

Sample Coding and Data Management

The current electronic systems for sample and data management (LIMS-NWQL, NWIS-IQWDATA, and NWIS-I-QADATA) do not provide a simple means of relating or differentiating

among ground-water-quality and QC samples obtained from a single well. Although there are

several ways to overcome this problem, the need to aggregate ground-water-quality and QC data

on a regular basis at the Study Unit and National Program level requires consistent coding and

management of samples and data among Study Units. For this reason, protocols for coding and

electronically storing routine QC samples and data were developed (tables 14 and 15). In the

case of topical QC data, coding is provided as part of each national topical QC-data request.
43

Table 14. Sample container coding requirements for ground-water-quality and routine qualitycontrol samples of the National Water-Quality Assessment (NAWQA) Program

[NWQL, National Water Quality Laboratory, Denver, Colo.; SC, laboratory schedule; LC, laboratory

code (in lieu of schedule); FA, filtered and acidified (nitric acid); RU, raw (unfiltered) and untreated;

FU, filtered and untreated]

_____________________________________________________________________________________

1. Routine ground-water sample-bottle labels:

• NAWQA and Study-Unit four-letter code: for example, “NAWQA-POTO” (for Potomac NAWQA

Study Unit)

• Local well identifier code

• Bottle type--NWQL sample designation schedule or laboratory code: for example, FA-SC2750

• Date of sample collection (MM-DD-YY, month-day-year), for example, 06-31-94

• Time of sample collection (HH:00, hours-minutes, military time)a for example, 12:00

2. Routine quality-control sample-bottle labels:

• NAWQA and Study-Unit four-letter code, same as above

• Local well identifier code, same as above

• Bottle type--NWQL schedule or laboratory code, where schedule or laboratory code used is given

 below

• Date of sample collection (MM-DD-YY, month-day-year), same as above

• Time of sample collection (HH:MM, hours-minutes, military time) where minutes are assigned

values other than 00, according to the following format:

Time Routine QC-sample type time-of-collection codes.b

HH:01 Replicate--organic-carbon, nutrient, pesticide, volatile-organic, radon or major ion

samples, use SC2085, SC2752, SC2001 and SC2050, SC2090, SC2091, or SC2092,

LC1369, and SC2750 (FA, RU, and FU), respectively. (For replicate cartridges, use

SC2010 and SC2050, in lieu SC2001 and SC2051, respectively. Replicates for pesticide

and volatile-organic compounds are optional.)

HH:02 Field spike-1st--for pesticide or volatile-organic samples, use same schedules cited under replicates above.

HH:03 Field spike-2nd--for pesticide or volatile-organic samples, use same schedules cited

under replicates above.

HH:04 Field spike-3rd (optional)--for pesticides or volatile-organic samples, use schedules

cited under replicates above.

HH:05 Field blank--pesticide, volatile-organic, organic-carbon samples--(which require

NWQL pesticide and VOC-free blank water, or if no field blank for VOCs taken,

require NWQL pesticide-free blank water), use same schedules cited for replicates

above. Field blank--nutrient samples (which require QWSU inorganic-free blank

water), for SC2752.

HH:06 Field blank--major-ion (which require QWSU inorganic-free blank water) for

SC2750.

HH:07 Solution blank--organic carbon only, (required because NWQL blank water is not

analyzed for organic carbon), use SC2085.
44

Table 14. Sample container coding requirements for ground-water-quality and routine qualitycontrol samples of the National Water-Quality Assessment (NAWQA) Program--Continued

_____________________________________________________________________________________

Time Routine QC-sample type time-of-collection codes.b

HH:08b Trip blank--volatile organic samples only (which requires NWQL trip blanks

found in box that sample vials are obtained in), use SC2090.

HH:09b Primary trace-element ground-water-quality sample, such as for SC2703.

HH:10b Replicate trace-element ground-water-quality sample, such as for SC2703.

HH:11b Field blank--trace-element samples only (which require QWSU inorganic-free

water), and in lieu of SC2703 use SC172 and add LC0112 (arsenic) and LC0087

(selenium).

 HH:12b Standard Reference Sample--for trace-element samples only, such as for SC2703. _____________________________________________________________________________________

a

This is a generic time value--the nearest hour to the true time--that is the basis for linking samples

taken from a well during a particular visit. Some situations, or samples, require the true time of collection

also be recorded--for example, to identify the time at which radon is taken. True time can be recorded,

along with the reason it is being recorded, on the field form, as in the case of radon, in the message to the

laboratory section on the NWQL-ASR form.

bExcept for trace elements (for example, SC2703), additional sample bottles under other schedules can

be added under the above time codes if and only if (1) they do not contain analytes in common with the

samples and schedules already listed, and (2) if they are composed of blank water, it is the same type of

blank water being used for the samples already listed above. If these conditions cannot be met, use other

time codes (and NWQL analytical service request forms) for the additional samples. Note that for trace

elements, unique time codes are required.
45

Table 15. Storage and coding requirements for ground-water-quality and quality-control samples

and data of the National Water-Quality Assessment Program

[NWIS-I, National Water Inventory System; QWDATA, Quality of Water Data Base; QADATA,

Quality-Assurance Data Base; NWQL, National Water Quality Laboratory; BTD&QS, Branch of

Technical Development and Quality Systems; QWSU, Quality Water Service Unit; mL, milliliters]

______________________________________________________________________________

1. Data Storage (check District policy):

• Routine ground-water-quality data in NWIS-I (QWDATA) database.

• Routine quality-control data in NWIS-I (QADATA) database.

• Topical quality-control data in NWIS-I (QADATA) database.

2. Sample and Data Coding on Analytical Service Request (ASR) Forms:

• Use same local well identifier as on sample container, add corresponding station

identification code (15-digit latitude-longitude-sequence number) and use same date for

all ground-water and quality-control samples collected at a well during a site visit.

• Use different time-of-sample collection codes for quality-control samples.1

• Use additional codes below for quality-control samples (in accordance with BTD&QS):2

For BLANKS: Coding required

Blank Blank Blank

Blank Sample Sample solution solution sample

type medium type type source type

(99100) (99101) (99102)

Trip Q 2 10, 40, or 50 10, 60, or 80 30

Equipment Q 2 10, 40, or 50 10, 60, or 80 80

Field Q 2 10, 40, or 50 10 or 80 only 100

Solution Q 2 10, 40, or 50 10 or 80 only 1

where Q denotes an artificial sample; 2 implies a blank sample; blank

solution type 10, 40, or 50 implies inorganic-free, pesticide-free,

or volatile-organic-free blank water, respectively; blank solution

source 10, 60, or 80, implies blank water from the NWQL,

District, or QWSU (Ocala), respectively; blank sample type 30,

80, 100, and 1 correspond to the blank types specified in the first

column, respectively. Only NWQL or QWSU water should be

used for field blanks. Record lot number of blank solution on

ASR form.3

For REPLICATES: Coding required

Sample Sample Replicate

medium type type

(99105)

Regular

sample 6 7 20

Second

sample S 7 20

where 6 implies a ground-water sample; S implies a replicate ground-water

sample; 7 implies replicate samples; and 20 implies samples were

collected sequentially.
46

Table 15. Storage and coding requirements for ground-water-quality and quality-control samples

and data of the National Water-Quality Assessment Program--Continued

_____________________________________________________________________________

2. Sample and Data Coding on Analytical Service Request (ASR) Forms--continued

•Use additional codes below for quality-control samples (in accordance with BTD&QS)2-- continued

For SPIKED SAMPLES (pesticides and volatile organic compounds):

Coding required

Volume

Sample Sample Replicate Type of Source of of spike

medium type type spike spike (mL)

(99105) (99106) (99107) (99108)

For each

spiked sample S 1 20 10 or 20 10 0.1

where S denotes a replicate ground-water sample; 1 implies a spiked sample;

20 implies a sequentially-collected sample; 10 or 20 implies spike was

done in field, or at NWQL, respectively, 10 implies source of spike

solution was the NWQL (required); 0.1 implies a 100-microliter volume

of spike solution was used. Record lot number of spike vial on ASR

form.3

For REFERENCE SAMPLES (of trace elements, obtained from BTD&QS):

Coding required

Sample Sample Reference

medium type type

(99103)

For each

reference Q 3 35

sample

where Q denotes an artificial sample; 3 implies a reference sample; and 35 implies

a reference sample that is a blend of standards. Record reference sample

bottle code as received from BTD&QS on ASR form.3

______________________________________________________________________________ 1Use different time codes to distinguish QC samples and prevent data overwrites (see table 14).

2Storage of ground-water-quality and quality-assurance data in NWIS, Branch of Quality Assurance

Memorandums 90.03 and 92.01 (unpublished memorandums located in the USGS BTD&QS, P.O. Box

25046, Mail Stop 414, Denver Federal Center, Lakewood, CO 80225).

3Write message to lab on comment line on ASR form.
47

To easily group ground-water-quality and QC data from selected sites, the containers for

these samples are coded in a systematic manner that employs some common codes (table 14--

NAWQA Study-Unit code, local well-identifier code, schedule or laboratory code, and date of

collection). For example, ground-water-quality and routine QC samples from the same well and

time of site visit are given the same local well-identifier code (on sample containers), and the

same local well and 15-digit (latitude-longitude-sequence number) identification codes in

NWIS-I, and the same date of collection (on containers and in NWIS-I). These common codes

facilitate linking selected types of samples (field blanks with the ground-water sample collected

before the blank was taken, one replicate sample with another, or a spiked sample with an unspiked sample). If common codes are not used, recoding, or the creation of additional codes by

the Study Unit, will be needed to link data requested by the National Program. In either case,

the Study Unit will be adding unnecessarily to its workload.

To manage sample data efficiently, and reduce confusion, it is best if routine QC sample

data are stored and managed through NWIS-I QADATA, and ground-water-quality sample data

are stored and managed through NWIS-I QWDATA (table 15). Efficient data management, reduced data loss, and improved ease of interpretation also are best achieved if different routine

QC-sample types, taken in relation to the same well and time of site visit, are uniquely coded in

at least some respects, and ancillary information that relates to each routine QC-sample type is

documented on the ASR form (tables 14 and 15). Thus, different time, medium, and QC-sample

codes are used for different types of routine QC samples. Ancillary information, such as the lot

number of the blank water or the spike solution, also is coded and essential to interpreting QC

data correctly. Illustrations of how data and codes are to be stored are provided for each type of

QC sample routinely collected (see appendix).

Consistent coding benefits each Study Unit in several ways. First, except for a few codes,

such as time of sample collection, most sample containers and forms generally can be filled out

before the field team departs for sampling. Most of this same information also can be logged

into NWIS-I in advance. This report (tables 14 and 15 along with the appendix) provides a comprehensive summary of appropriate codes that are needed to complete these presampling coding

and management activities.

The prescribed codes will reduce the loss of data through overwrites. Data overwrites can

occur in several ways. For example, one of the most common overwrite problems occurs when

two different sample containers and their corresponding ASR forms have the same identification,

date, and time codes, and one inadvertently requests analyses that involve at least one common

analyte (parameter code) for both samples. Another common problem arises when one makes

corrections to NWIS-I (QADATA or QWDATA), but does not have these processed through

NWQL-LIMS. In either case, corrections are overwritten and data can be lost electronically

when the NWQL submits or resubmits analytical results to NWIS-I through LIMS original

record or provides updates to this record. To avoid problems, the Study Unit must code samples

correctly. In addition, if corrections are made in the District, the Study Unit also must request

the corrections be processed through the NWQL-LIMS system.
48

The prescribed codes will ensure that the sample container for a particular analysis is used

for that analysis. For example, if sample containers are sent for major ions (SC2750--FA) and

trace elements (SC2703--FA), they must be sent under separate ASR forms with different times

to ensure that the trace-element analysis is done using the SC2703 sample and not the SC2750

sample. Because of potential differences in filter loading that affect filtrate concentrations

between these two samples, it is critical that trace-element data come from an analysis of the

SC2703 sample.

Finally, use of the prescribed codes (tables 14 and 15) is necessary for requests from the

National Program for ground-water and QC data. If alternative coding is used, the data will need

to be recoded by the Study Unit before the data are forwarded to the National Program.

Final Presampling Plans and Preparations

During the last month or two before the first field season for data collection begins, the

Study Unit will complete presampling plans and preparations. This will involve a number of

activities (table 16) that, in addition to scheduling water-quality and QC sampling, will include

the following:

1. Creating a field file that contains copies of all the information needed for the current

sampling run;

2. Preparing sample containers and filter units;

3. Checking that all the equipment and supplies needed for sample collection at each well

listed in the file have been obtained and safely stored in the vehicle; and

4. Checking that the vehicle is in good and safe working condition, and that safety equipment is present and functioning properly.

In addition to the well schedule (table 7), the field file contains information critical to completing activities at each well (table 16), which could differ among wells. As sampling continues, the file is updated regularly in terms of those wells scheduled for data collection throughout

the remainder of the field season.
49

Table 16. Activities related to final plans and preparations before sampling begins

_____________________________________________________________________________

1. Create a field file, in part, from previously collected information, that contains:

• A well schedule (chronological list of wells to be sampled during the scheduled run).

• A checklist of the sample and data-collection activities to be carried out at each well--

(a) a list of analytes to be sampled--by bottle type (for example, FA), in order of collection

 and processing, including quality-control samples,

(b) a list of information required, and the necessary forms, to complete any documentation

not completed during previous site visits, and

(c) a form for noting changes in, or providing additional information on, land use.

• Copies of site, well, measurement point, and sampling setup location maps and

photographs for each well.

• Notes on any special site conditions that could affect sample and data collection at a well,

including roaming animals and locked gates, or a well, that on the basis of

screening tests, might require special QC sampling and decontamination procedures.

• The contact person’s (well or land-owner’s) name and telephone number for each well.

• Field cover, well-purge, Analytical Service Request, and field-instrument calibration

forms--completed to extent possible for each well. Also include some extra, blank copies

of each form. (Calibration notebooks can be used instead of individual forms.)

• Overnight-mail shipping forms and labels, completed to extent possible, and the shipper’s

telephone number.

• Study-Unit (SU) sample-transfer and temperature-check form for NWQL (Sample login)

with SU-addressed, stamped envelope for each well. (Also have the telephone number for

NWQL (Sample login)).

• Calibration notebook(s) for field meters.

• Copies of the NAWQA protocols for sample and data collection, and the U.S. Geological

Survey National Field Manual for Collection of Water-Quality Data (Radtke and Wilde,

in press).

2. Prepare sample containers and filter units that are:

• Cleaned if necessary,

• Labeled to the extent possible, and

• Bagged, for each well,

• With each container tightly capped. (Recommend plastic container be half filled with DIW.)

3. Provide routine checks that cover the equipment and supplies stored in field vehicles

(see table 3 for detailed list), for:

• Calibration and use of field meters for temperature, pH, acid-neutralization capacity,

alkalinity, specific electrical conductance, dissolved oxygen, and possibly turbidity.

• Collection, processing, preservation, and, possibly field extraction of ground-water and

quality-control samples.

• Field-equipment decontamination.

• Sample shipment or temporary storage.

• Disposal or temporary storage of waste materials.

4. Provide predeparture checks each time the field team leaves the District office or a well that:

• Cover vehicle safety and condition.

• Ensure all field equipment is properly and safely stored.

______________________________________________________________________________
50

As part of the final presampling preparations, some sample containers require rinsing

(table 16). For example, it is required that all sample containers and caps for filtered and acidified samples (FA designation), which includes those for major ions and trace elements, be rinsed

at least three times with either QWSU IBW or DIW -- ASTM Type 1 water (conductivity less

than 1.0 μS/cm at 25°C). It is recommended, however, that FU, RU, and FCC containers also

be rinsed as described above before use. After the final rinse, it also is recommended, as a QC

measure on the container seal, that each container be half-filled with the same water used for

rinsing and capped before storing the container for transport to the field. If the container is less

than half full when pulled from storage in the field, the container is discarded, and another similarly rinsed container is used in its place. This implies that several additional containers for each

sample type are prepared as above and in advance of at least the first field-team trip. After rinsing, sample containers can be labeled with the appropriate codes, except for date and time of collection, before they are transported to the field. This will reduce the time necessary to complete

setup activities in the field before samples are collected.

Although at least three different filter units commonly will be used (table 3), only the one

for filtered inorganic samples, the 0.45-μm fibrous filter (capsule), can be prepared before the

field team departs for the field. It is required that 1.0 L of QWSU water or DIW (ASTM-Type1) be passed through this filter before it is used. Preconditioning is to occur within 5 days before

use. A peristaltic pump head with Tygon tubing, or a Teflon diaphragm pump head with convoluted Teflon tubing can be used to force the preconditioning water through the capsule filter. The

pump also is used to force as much water as possible from the capsule after it is preconditioned.

To avoid mildew, the preconditioned capsules are placed in nested, resealable plastic bags and

stored in a cool environment (refrigerator or cooler with ice) before use.

Different filter units might need to be prepared to address topics of interest germane to a

specific Study Unit component. A Flowpath Study that involves geochemical modeling and other techniques to interpret dissolved inorganic chemical data from ground water requires additional samples be obtained with these samples filtered through a membrane with a pore size of

0.2 or 0.1 μm or less. Currently, only flat (plate) filter membranes are available with a pore size

of 0.1 μm or less. Preparation of these membranes and the equipment needed is described in an

internal document (F.D. Wilde, U.S. Geological Survey, written commun., 1995--see footnote

1). To determine the appropriate filter type and pore size, it is recommended that a comparison

sample analysis be made between data obtained from NAWQA samples passed through 0.45−

μm capsule filters and Study-Unit samples passed through 0.1−μm membranes to determine if

there is an appreciable difference in trace-element concentrations.

Final plans before sample collection include the office support effort required to maintain

the field effort. The field effort typically involves repeating activities (such as those in table 16)

on a regular basis during a single field season. To plan for the office support needed, consider

that each time the field team returns: (1) the sampling vehicle(s) generally is (are) unloaded,

cleaned, and restocked; (2) forms and other information are transferred from field to office files;

(3) the field file is restocked with information on the next set of wells to be sampled; (4) samples

brought from the field are archived or shipped from the office; and (5) field and sample-related

data and forms are transferred to data managers, with copies being archived into NAWQA site

files.
51

If the planning document or workplan assigns all of the above activities solely to the field

team, their field schedule must allow ample time to complete these activities. The workplan also

should reflect that team members could have a backlog of work pending as a result of their absence. A field team that keeps good records in the field--of supplies that are running low, or of

equipment that is in need of repair or replacement--can expedite preparations for the next field

effort. While in the field, mobile phones also provide an efficient means of communicating

needs in advance or when emergencies arise.

During final preparations, Study-Unit data managers integrate their plans to review the

data-collection process. Workplans, developed during the last month or two before sampling

begins, include verification of field forms returned by field teams, the login of sample and data

information from these forms, and the updating of any new information (such as changes in land

use). Workplans also include regular retrievals and quality-control checks on NWQL data returns. Of particular importance is the timely retrieval and evaluation of routine QC data, which

can be used to assure field teams that data collection can continue unabated. Finally, data management workplans are to include the development of NAWQA water-quality files for wells at

which ground-water samples are collected. These files generally are distinct from other files,

such as the GWSI file, in that they chiefly contain records and information pertaining to groundwater-quality sampling. Thus, each of these files contains copies of sample-collection field

forms, NWQL and other laboratory request forms, and water-quality-data summaries (in particular, NWIS-I site and time-specific lists (WATLISTS) of water-quality data).

Field Protocols and Recommended Procedures

A field team could spend 2 to 5 hours traveling to and from each well that is scheduled for

the collection of ground-water-quality samples. At each well, the team will perform some, or

all, of the following activities:

(1) Equipment setup.

(2) A well purge, to remove standing water, and field measurements.

(3) Sample collection and processing.

(4) Decontamination of field equipment, including possible breakdown and storage

of sampling equipment.

(5) Preparation of blank samples.

(6) Preparation of other routine quality-control samples and field extracts for

pesticide samples.

(7) Handling and shipping of samples, including completion and verification of field,

 laboratory, and other forms.

Each activity is described below in its approximate chronological order of occurrence.
52

Equipment Setup

Upon arrival, the field team contacts the land or well owner (if necessary), and locates the

well and areas for conducting on-site activities (table 17). The field team carries out the remaining setup and other on-site activities after selecting one field-team member, hereafter referred to

as Team Member A, who is responsible for the collection of all water-quality samples throughout the day. From this point on, Team Member A generally performs only those on-site activities that are least likely to lead to the contamination of samples during or after collection. The

other field person, Team Member B, also performs activities required in order to collect samples and data, but in some cases the activities performed potentially heighten the risk of sample

contamination if that person also were to collect water-quality samples.

Field team roles, which are maintained throughout the day regardless of the number of

wells visited, are alternated between team members on a regular, preferably day-to-day, basis.

This ensures that each team member can perform all on-site activities associated with groundwater-quality data collection.

It is recommended that team members wear clothing appropriate to their assigned activities. Team Member A wears clothing that is tightly knit and not likely to shed lint. Powderless

latex (when using methanol) or powderless vinyl gloves are required. Team Member B initially

wears work gloves and coveralls over attire, similar to that of Team Member A. Work gloves

and overalls are removed after the completion of setup activities that involve handling equipment that could be heavily soiled or contaminated (table 17). Team Member B also is required

to wear powderless latex or vinyl gloves during sample handling and preservation. Safety

goggles or glasses are worn whenever either team member is handling chemical reagents that are

potentially toxic or hazardous.

Well Purging, Grab Samples, and Field Measurements

Before water-quality samples are collected, the well is purged of standing water. Grab

samples taken near the end of the purge are used to determine (1) the amount of NWQL hydrochloric acid needed to acidify the VOC samples, and (2) the normality of QWSU sulfuric acid

to use for field titrations. Field data are obtained during the latter stage of the purge, immediately

before sample collection. The purge, as well as grab-sample analyses and field measurements,

are carried out in an efficient, and to the extent possible, consistent manner throughout the

NAWQA Program (table 18).

The well purge ensures that the field-measurement and sample data that are subsequently

collected reflect the chemistry of water in the aquifer, and not that of the water that has been

standing in the well. The purge also conditions sampling equipment and reduces turbidity (sediment and colloids) caused by either the lowering and start-up of a portable pump, or the startup of a water-supply pump.
53

Table 17. Initial field-team setup activities related to on-site protocols and procedures at wells

used for ground-water-quality and routine quality-control data collection for the National WaterQuality Assessment Program

______________________________________________________________________________

1. Field team arrives, consults field file (table 16), and carries out initial setup activities as

 follows:

•Contacts land or well owner (if necessary)

•Verifies following points and areas of interest (modify site-file maps and update photographs

and forms as necessary):

Land use and land cover in vicinity of well1

Well location and water-level measurement point

Parking areas for vehicle(s)

Areas for field-equipment setup and well-water discharge

2. To provide quality assurance, the field team divides remaining setup duties, which are carried

 out as follows:

•Team Member A

Calibrates and sets up field instruments for titrations, turbidity, and flowthrough chamber2

Assembles sample-wetted equipment for purge and collection3

Completes labeling of sample containers and forms (primarily by adding date and time of

collection)4

•Team Member B

Sets up safety cones (as needed)

Measures water levels (if possible, static depth to water and depth of well)3

Checks for oil residues in well (on measurement tape)

Calculates purge volume (from well diameter and depth measurements, otherwise assumes it

equals three casing (or wellbore) volumes)5

Attaches waste lines to purge setup (see fig. 2, routes to prevent flooding in work area

and near power supplies)

Sets up pump system (as needed, fig.2, for monitoring well, in well drained area)

Sets up power supply (for portable pump, avoids wastewater areas; using vehicle power,

checks fuel is sufficient, attaches exhaust hose(s) to vehicle(s), and voids exhaust downwind

of work areas; using portable generator, checks and, if necessary, fills fuel tank)

______________________________________________________________________________ 1See appendix, figure A1, and update as necessary.

2According to “Field Instruments” section and appendix, figures A2 to A6.

3See text and figure 2.

4According to “Sample Coding and Data Management” section and appendix, figures A8 to A20.

5See appendix, figure A7.
54

Table 18. Field-team activities for purging a well for ground-water-quality and quality-control

data collection

[NWQL, National Water Quality Laboratory; HCl, hydrochloric acid; VOC, volatile organic compound;

QWSU, Quality Water Service Unit; mL, milliliter; H2SO4, hydrosulfuric acid; ANC, acid-neutralizing

capacity; ALK, alkalinity]

______________________________________________________________________________

1. Field team identifies approach to be used to purge well on basis of:

• Standard purge protocol (see table 19)

• Recent pumpage from well

• Possible use of packers

• Well capacity

• Possible use of other customized purge criteria

• Well type (monitoring or water-supply well)1

2. Field team divides site duties on the basis of assigned roles for the day, and carries them out

 as follows:

Team Member A

• Records flow rate and volume of flow from the well and through the equipment setup.2

• Collects grab samples near end of purge to determine and record:3

(1) the number of drops of NWQL HCl required to reduce the pH of VOC 40-mL sample

 to 1.7 to 2.0 (to a maximum of 5 drops for VOC sample preservation), and

(2) the normality (1.6 or 0.16) of QWSU H2SO4 titrant, and volume in milliliters (50 or

 100) of the ground-water sample (for field titrations of ANC and ALK).

• Records field measurements, including final median values required under protocol.2

Team Member B

• Conducts purge (and routes flow as needed to obtain field measurement data (see fig.2)).

• Adjusts and measures initial and final flow rates through purging setup and pump rates in

well (as required and needed)1.

• Monitors (if necessary) pump work rate (amperage) and power supplies (fuel levels).

Both Team Members

• Assess stability of chemical and physical measures to determine when samples are collected.4

• Document decision on whether or not to sample, and why.

______________________________________________________________________________ 1See text, including section on “Purging Different Types of Wells.”

2See appendix, figure A7.

3See “Grab Samples for Titrations and Volatile-Sample Preservation” and appendix, figures A8 and A9.

4See “Final Assessment of Chemical Stability.”
55

Figure 2. Schematic of equipment setup for well purge and sample collection.

Sample-collection


chamber

Extension


line

(2b)

(2a)

(2) (1) To waste-water drainage

Manifold

To waste-water drainage

SC T

DO

pH

Flowthrough


chamber

Extension


line

From the portable pump used for a monitoring 


well, or from the garden-hose-threaded 


connection for a water-supply well

(1) During initial purge stage


(2) During intermediate and final stages


(2a) To obtain most field measurments


(2b) To obtain turbidity samples, and


 at end of purge to route flow


 for collection

EXPLANATION


Rigid-wall Teflon tubing


Quick connection

 Dissolved-oxygen sensor


 Temperature sensor


 pH sensor


 Specific electrical conductance


 sensor

DO

T

SC

pH

Antibacksiphon


Three-way Teflon flow valve

Flow direction, at different times Field sensors (flowthrough chamber)

To obtain most field measurements
56

Despite differences in scientific opinion as to when and how much purging are necessary,

and the criteria used to assess when purging is complete, NAWQA field teams will use the standard USGS procedures and criteria for purging and collecting field measurements (table 19). In

applying the purge protocols, the equipment and procedures used can differ in some respects on

the basis of recent pumping, well capacity, study component, and well type (see below). With

some exceptions, the same equipment (fig. 2), criteria (table 19), and similar procedures are used

to purge and collect ground-water-quality samples. Deviations from the standard purge protocols that are not described below are discussed in advance, if possible, with the NAWQA QA

Specialist.

Acceptable deviations from standard purge protocols

Four possible exceptions to the standard purge procedures are recognized and accepted.

The first relates to recent pumping. If it can be documented that a volume of water equivalent to

the purge volume already has been pumped from a water-supply or monitoring well within the

24-hour period before the field team arrives, sample collection can begin after equipment has

been flushed or “conditioned” with ground water and field measurements have been shown to be

stable. This effectively reduces the purge time to that needed to achieve stable field measurements (table 19, minimally about 15 to 25 minutes).

The second exception to the standard purge protocols relates to well capacity. When the

permeability of the aquifer is low, and a slow recovery limits well capacity, it often is possible

to quickly evacuate the standing water from the well. For a monitoring well, the field team lowers the pump intake slowly, and evacuates the well at a pump rate that does not suspend sediments. Field measurements and samples are obtained after the water level has recovered to at

least 90 percent of the level measured before evacuation, and provided recovery occurs within

24 hours of evacuation.

The third exception to the standard purge protocols also relates to well capacity. When

packers have been placed in a well to restrict the zone of water withdrawal, the purge volume is

equivalent to three times the volume between the packers. Given that this purge volume could

be quite small, the field team again could find that only a 15- to 25-minute purge at the low flow

rate is needed to remove the necessary water and obtain stable field measurements. As a qualitycontrol measure, pressure transducers, installed above and below the packers, are recommended

to determine that leakage is not occurring across packers or from above or below the zone

isolated for sampling.

The fourth exception to the standard purge protocols is related to the ground-water component sampled. When purge criteria can be customized for the well and in relation to specific sampling objectives, these purge criteria can be used in place of the standard criteria. This

exception is most appropriate for investigations that focus on a specific, but limited group of

analytes, such as in a NAWQA Flowpath Study (table 1). In fact, it is recommended that Study

Units develop and use purging procedures and criteria that best correlate with the concentrations

of analytes being investigated. For example, a customized purge criteria for sampling VOCs is

described by Gibs and Imbrigiotta (1990).
57

Table 19. Standard protocols and recommended procedures for conducting and assessing

well purging for the National Water-Quality Assessment Program (modified from F.D. Wilde,

U.S. Geological Survey, written commun., 1995--see footnote 1)

[Assumes that well capacity is not a limiting factor; see text for further discussion of exceptions.

°C, degrees Celsius; %, percent; ≤, less than or equal to; >, greater than; <, less than; μS/cm, microsiemens per centimeter at 25°C; mg/L, milligrams per liter; NTU, nephelometric turbidity units]

_____________________________________________________________________________________________

1. Purge a minimum volume of water equal to three times the casing (or wellbore) volume.1

2. Reduce rate of flow from well, if possible, but at least through setup, to no more than about

0.1 gallon (~500 milliliters) per minute for 15 to 25 minutes near end of purge (samplecollection rate).2

3. Monitor pH, temperature, specific electrical conductance, and dissolved oxygen throughout the purging process, but particularly during last 15 to 25 minutes. (If trace-element

samples are being collected, include turbidity measurements as part of monitoring.)

4. The well is considered purged after at least three casing volumes have been removed

and values of monitored parameters between 5 successive measurements separated by

about 3- to 5-minute time intervals are within the allowable difference specified below:

 Parameter Allowable difference or value

 pH ± 0.1 units (± 0.05 units if instrument displays

2 or more digits to the right of the decimal)

 Temperature ± 0.2°C (thermistor)

 Specific electrical conductance (SC) ± 5%, for SC ≤ 100 μS/cm

± 3%, for SC > 100 μS/cm

Dissolved oxygen (DO) ± 0.3 mg/L

 Turbidity (TU) ± 10%, for TU < 100 NTU: ambient TU is

<5NTU for most ground-water systems

(visible TU > 5 NTU)

•If measurements appear stable, the median value of the last five measurements for each

parameter (except for pH) is recorded on the appropriate forms (see appendix, figs. A7 and A8),

and the field team proceeds with sample collection. For pH, only the last measurement is

recorded.

•If criteria for stability is not achieved, purging is continued until either the field measurements stabilize, or the equivalent of five or more wellbore or casing volumes have been

removed, depending on the judgment of the field team. The field team records the final field

measurements in the manner noted above, and notes any parameters which remain unstable.

•If measurements remain unstable, the field team must decide whether or not to continue with

sample collection.

•A lack of stability, indicated by a consistent trend in values upward or downward for pH, SC,

DO, and TU, indicates possible problems in well design, or purging setup or technique. It is

recommended that samples not be collected from a well if the setup or technique cannot be

altered to obtain stable measurements. _____________________________________________________________________________________________

1Standing volume is calculated from depth to water and depth of well measurements (see appendix,

fig. A7).

2If a high initial rate is used, reduce rate of flow from well and through purge-collection setup to

this rate.
58

Each of the above exceptions actually fulfills the intent of the standard protocols. In each

case, the procedures and criteria used ensure the removal of stagnant water, and the chemical and

physical stability in flow before samples are collected. In addition, and regardless of what purge

criteria are used, the standard field measurements (DO, SC, T, pH, and, if trace-element samples

are collected, TU) also are determined and documented. They are part of the NAWQA data collected at each well (table 1). Thus, except for pH, the median value of the last five stable values

for each standard measurement, and any customized purge criterion, are recorded as part of the

data of record. For pH, only the last measurement is recorded.

Purging with different flow rates

With the exception of some Study-Unit Survey Flowpath-Study components (table 1),

wells used by NAWQA generally are completed at relatively shallow depths in water-table

aquifers. As a general rule, the purge procedures described above are completed within about

2 to 2 1/2 hours, which includes the 15- to 25-minute period at the low flow rate required for

sample collection (about 0.1 gal/min or 500 mL).

A low flow rate is required at the end of the purge (and during sample collection) for consistency and technical reasons. In combination with a portable, submersible pump, a low flow

rate:

(1) is obtainable and maintainable for most, if not all, wells;

(2) reflects a discharge that can be sustained at low pump amperage and without surging;

(3) reduces the likelihood that sources of ground water entering the well will change (Reilly

and others, 1989);

(4) is likely to lead to uniform, or at least less turbulent, flow;

(5) reduces the potential for degassing of some constituents, such as VOCs and radon;

(6) reduces the likelihood of entraining colloids and other artifacts dislodged and suspended

by turbulence; and

(7) provides a rate of flow that is manageable during sample collection.

To achieve some of the above in sampling water-supply wells when the rate of flow

through the well is high and uncontrollable, part of the flow is diverted (through the equipment

setup) at the required low rate.

Although use of a higher rate of flow throughout the purge and sample-collection period

than that required near the end of the purge reduces purge and sample-collection times, it also

reduces the likelihood that the benefits described above will be achieved. As a compromise that

aids in reducing field times, while maintaining some consistency and quality control, higher flow

rates (during the initial part of the purge) than the required low flow rate (near the end of the

purge) can be used provided these conditions are met: (1) that the high flow is sustainable, (2)

that the high flow is not highly turbulent, (3) that field measurements, including turbidity, which

could change precipitously at first under the high flow, stabilize relatively quickly, and remain

about the same (no abrupt changes), and (4) that turbidity, in particular, does not remain elevated, but approaches a generally acceptable value (table 19).
59

Purging different types of wells

Perhaps the most substantial differences among wells that the field team could encounter

in applying the standard purging protocol (table 19), or one of the acceptable deviations to that

protocol, occurs in relation to well type (monitoring or water-supply well). Because watersupply wells for NAWQA are chosen on the basis of suitable construction for ground-waterquality data collection (Lapham and others, in press), they are equipped with pumps that can be

used to obtain water samples. The location of the well pump intake and the pump rate, however,

generally cannot be controlled by the field team. This implies that the field team only has limited

control of some aspects of the purge and sample-collection process at these wells. This is not

the case for most monitoring wells. Because data collection at most monitoring wells selected

by NAWQA will require the use of a portable pump whose intake location and flow rate can be

modified, the field team has considerable control over the purge and sample collection process

for this type of well. Despite the differences in level of control between water-supply and monitoring wells, and to promote consistency in purging and data collection from these two types of

wells, it is required that field teams follow the standard procedures (table 19), when possible, or

follow acceptable alternative procedures for purging each type of well. Further guidance on

purging either type of well is provided below.

Water-Supply Wells. Water-supply wells used by NAWQA are selected, in part, because

they have pumps deemed suitable for producing samples of suitable quality. The field team,

however, generally cannot alter the rate at which these pumps operate, nor the location of the

pump intake. Generally, the field team only can control the flow rate through their own equipment when purging or collecting samples.

To determine the manner in which the purge of a water-supply well is conducted, the field

team first estimates the volume of water that will be removed from the well using the groundwater supply-pump rate and the final 15 to 25 minutes of purging (when stability measurements

must be made). If the estimated volume is about equal to or exceeds the required purge volume,

then evacuation of the required purge volume will take only about 15 to 25 minutes. In this case,

the field team sets up the equipment and then conducts the purge. This situation commonly arises for small water-supply wells, such as those used for single dwellings. Setting the equipment

up first, and then purging this type of well will prevent overpurging, which could adversely affect the quality of data obtained by NAWQA for some VOCs (Gibs and Imbrigotta, 1990).

For a water-supply well that requires a purge time considerably longer than 15 to 25 minutes (for example, more than 2 hours), the field team has the option to request that the well pump

be turned on before they arrive. This approach commonly is needed for high-capacity wells used

for irrigation or drinking-water supplies. The field team arrives, however, in time to set up

equipment, complete the final 15- to 25-minute phase of purging using the low flow rate through

their equipment, and obtain stable field measurements before the required purge volume is evacuated. If this option is used, the field team also requests that static water-level data be collected

by the pump operator before pumping begins.

As a final consideration in purging a water-supply well, the field team keeps the watersupply pump operating throughout the purge and sample collection. This ensures the removal
60

of standing water from the well, and clears standing water from any plumbing lines leading to the

sampling equipment.

To ensure the water-supply well continues to operate, the field team can open more flow

valves than just the one connected to their equipment. This also will reduce the likelihood of backflow of water stored in plumbing lines that could be connected to the line that transports water to

the sample-collection setup. Backflow often occurs if the plumbing system is not equipped with

antibacksiphons. Antibacksiphons generally are absent in secondary distribution lines on lowcapacity supply wells, such as those used by rural homeowners for local supplies.

Since water-supply pumps operate continuously during the purge and sample collection,

there is a chance that the supply pump could burn out. Although most commercial pumps are designed to operate for hours without problems, old, worn pumps are a potential problem. If a pump

burns out, the field team generally should expect to replace it upon the owner’s request. To limit

the chance of pump burnout, the field team needs to work quickly and efficiently to keep the total

pumping time required to purge and sample as short as possible. If this is achieved by using a high

flow rate, through setup equipment, this flow rate is reduced to about 0.1 gal (500 mL) per minute

during the final stage of the purge and during sample collection.

Monitoring Wells. Because the field team supplies the pump, they control the rate at which

water is pumped from the well and through their equipment, as well as the location of the pump

intake in the well. During the purge of a monitoring well, it is important to recognize that pump

intake rate, emplacement, and location can influence the quality of the water obtained. Thus, it is

important that these pumps be used in a consistent manner for the purge and sample collection at

different monitoring wells.

As in the case of a water-supply well, the first step in applying the purge protocol to a monitoring well is to determine if the required purge volume can be evacuated in the 15 to 25 minutes

needed for field measurements at the required low-flow rate for sample collection. For this 15- to

25-minute period, and a rate of about 0.1 gal (500 mL) per minute, about 1.5-2.5 gal (7-11 L) will

be evacuated from the well. If the required purge volume is less than or equal to this volume, the

field team sets up all equipment and then purges the well at this low rate. If the required purge

volume exceeds about 1.5-2.5 gal, the field team can purge the well at an initially high, but acceptable, flow rate (as described earlier) to reduce the purge time, and then reduce the flow rate to the

sample-collection rate for the final 15 to 25 minutes of the purge, and take and document final field

measurements.

Pump intake emplacement is a consideration in the purge of a monitoring well. To reduce

the suspension of sediments in the well, the pump intake always is lowered slowly into the well.

Initially, the intake is placed just below the surface of the water standing in the well.

With the setup equipment properly configured to route flow directly to waste (fig. 2), the

pump is turned on at an initially low rate to avoid sediment suspension in the well. If the required

purge volume is small, and the entire purge can be conducted within 2 hours at the low rate required for final field measurements and sample collection, the pump rate is slowly adjusted to a

rate of about 0.1 gal (500 mL) per minute. This rate is verified by measuring the outflow from the

waste line, and recorded (appendix, fig. A7).
61

If the required purge volume is high, and an initially high pump rate is desired, the pump

rate is slowly increased until either the maximum acceptable flow (as described earlier) or pumping capacity is reached (because of pump limitations or well capacity). In general, unless the

well capacity is extremely low and purging cannot be completed within 2 to 2 1/2 hours, rapid

evacuation of the standing water in the well is avoided. As noted earlier, the initial flow rate is

measured at the waste-line outflow and recorded (appendix, fig. A7).

After the initial flow rate has been measured, the flow is rerouted through the instrumented

flowthrough chamber (fig. 2) and the purge continues. Field measurements are made and recorded from this point on (appendix, fig. A7).

As the purge continues, and to enhance the evacuation of all standing water, the pump intake in unpacked wells is lowered slowly until it resides a distance above the open (perforated,

or screened) interval that is equal to 7 to 10 times the diameter of the well casing (borehole).

Assuming the monitoring well was designed correctly with a short open interval of 2 to 10 ft

(Lapham and others, in press), this final location of the intake aids in promoting the flow of water

from the entire screened interval to the pump intake.

Any substantial changes in pump intake location (lift) could affect the flow rate. Thus, all

changes in pump intake location are completed before the final 15- to 25-minute stage of the

purge. At this time, any high pump intake rate is reduced to about 0.1 gal (500 mL) per minute,

and the last five sets of successive field measurements are taken, while the last of the required

purge volume is evacuated from the monitoring well.

Grab samples for titrations and volatile-sample preservation

During the final 15 to 25 minutes of the purge, or whenever measurements appear stable

in relation to the purge criteria (table 19), two grab samples are taken. The first is a 100-mL

sample which, if the pH exceeds 4.5, is quickly titrated to roughly determine the acid neutralizing capacity (ANC) of the sample (Radtke and Wilde, in press). From the ANC value, the field

team determines the optimum sample volumes and titrant normality (1.6 N or 0.16 N sulfuric

acid) to be used for subsequent, quantitative field titrations (table 20). If the sample pH is 4.5

or less, no field titrations for ANC or alkalinity are required.

If VOC samples are scheduled for collection at the well, a second 40-mL grab sample is

obtained in a clean glass beaker to determine the amount of NWQL hydrochloric acid needed to

preserve VOC samples (from March 31, 1993 to January 31, 1994, samples were preserved with

NWQL-concentrated hydrochloric acid). The acid is added drop by drop to this beaker, the sample is stirred or mixed, and the pH is measured after each acid addition until it is between 1.7 and

2.0. The number of drops of NWQL acid used must be recorded on field forms (appendix, figs.

A8, A10-A, A11-A, A12-A, and A13-A). To avoid damage to NWQL instruments, however,

no more than 5 drops of NWQL hydrochloric acid are to be added to a VOC sample (Bruce

Darnel, VOC National Synthesis Team, U.S. Geological Survey, written commun., 1995).
62

Table 20. Field-titration procedures for ground-water samples of the National Water-Quality

Assessment Program

[mg/L, milligrams per liter; mL, milliliters]

______________________________________________________________________________

• Except when replicate titrations are scheduled at selected wells, one filtered, and

(optionally) one unfiltered, sample will be titrated at each site.1

• The unfiltered sample is titrated for acid-neutralizing capacity (ANC, mg/L2). The filtered

sample is titrated for alkalinity (ALK, as mg/L CaCO3; carbonate, as mg/L CO3

–2,

bicarbonate, as mg/L HCO3

–; and hydroxide, as mg/L OH–).

• Conducted in the field on fresh samples by the incremental addition of titrant, generally

with digital equipment, and the recommended volume of sample and normality of titrant,

as follows:

Parameter(s) Expected Value Sample Volume Titrant Normality

ANC or ALK 0.0-50 mg/L as CaCO3 100 mL 0.16

ANC or ALK 50-200 mg/L as CaCO3 50 mL 0.16

ANC or ALK 200-1,000 mg/L as CaCO3 100 mL 1.6

ANC or ALK Exceeds 1,000 mg/L as CaCO3 50 mL 1.6

• Estimates of ANC, ALK, and contributing species are determined by the Inflection-Point

Method (Radtke and Wilde, in press). Inflection points to determine ANC or ALK and

contributing species are near pH values of about 8.2 and 4.5 for most waters buffered by

the carbonate system.

• If difficulties arise in determining titration endpoints--which could be encountered for saline,

low-conductivity, low-alkalinity, anoxic, or organic-rich ground waters--the Gran-Function

Plot Method is recommended (Radtke and Wilde, in press).

• Field titration data are recorded (appendix, fig. A9) and later stored electronically under

the appropriate parameter codes in NWIS-I QWDATA (for primary ground-water samples)

or NWIS-I QADATA (for replicate ground-water samples).

______________________________________________________________________________ 1Before 1996, titration of an unfiltered sample was required and titration of a filtered sample was

optional.

2Reporting values above assigns carbonate chemical species as the primary sources of neutralizing

capacity. At this writing, appropriate parameter codes are not available to enter data above in NWIS-I

in milliequivalent units.
63

Final assessment of chemical stability

The field team decides whether or not to collect ground-water-quality samples on the basis

of the relative stability of field measurements taken near the end of the purge, as the last of the

required purge volume is evacuated from the well (table 19). It is recommended that samples

not be collected if unstable field measurements persist. Unstable measurements generally indicate one or more of the following is true: (1) that the source of water entering the well is changing

with time, (2) that a decreasing proportion of water leaving the well is water that initially was

standing in the well, or (3) that water is entering the well in a disproportionate manner as time

elapses from a new source or from several sources. Thus, the resulting water-quality data obtained from sampling a well with unstable field measurements may or may not relate to the land

use, aquifer, or other conditions being investigated.

Sample Collection and Processing

Sample collection begins when purge criteria have been met. The type and number of individual ground-water-quality and QC samples obtained, however, depend on the ground-water

component (Study Unit Survey, Land-Use Study, or Flowpath Study) for which samples are

being collected (table 1). Study-Unit (or Subunit) Surveys and Land-Use Studies commonly

include the collection of samples for organic, inorganic, and possibly trace-element, radiochemical, and isotopic analyses. Flowpath Studies generally are limited in scope and require

fewer samples than either Surveys or Land-Use Studies. For each component, routine, and

possibly topical, quality-control samples also are scheduled for collection at selected wells.

Regardless of the particular component under investigation, protocols and procedures are

followed in a consistent, timely, efficient, and quality-controlled manner. The protocols and

procedures that follow describe the sample-collection methods to be used for NAWQA groundwater-quality studies (table 21), and include the collection and processing (filtration, preservation, handling, and shipment) of water-quality and QC samples for a given analysis. In addition,

the protocols also specify an order or sequence in which groups of samples for different analytes

are collected under these protocols, which generally is to be similar at each well in a given component, and among components with similar data-collection requirements.

Overall, the NAWQA sample-collection protocols and recommended procedures (table

21) follow USGS protocols and procedures (F.D. Wilde, U.S. Geological Survey, written

commun., 1995--see footnote 1). Thus, samples for organic analytes (unfiltered, then filtered)

are collected first, followed by samples for inorganic analytes (filtered, then unfiltered), which

in turn are followed by the collection of samples for other (ancillary) analytes--isotopes, radiochemicals, and chlorofluorocarbons (table 21). Routine replicate ground-water-quality samples,

including those for field spikes, are collected in conjunction with the primary ground-waterquality samples (table 21). (Routine QC samples that use blank water are collected in the

field after ground-water-quality samples and after the decontamination of sample-collection

equipment.)
Table 21. Collection order, processing, preservation, and field storage required for ground-water-quality and replicate samples for the National WaterQuality Assessment Program

[Except as noted, equipment used is described earlier (table 3). Except as noted, samples are (possibly filtered and) obtained in a collection chamber, and (if necessary)chemically preserved in another chamber. Except for filtered inorganic samples (see below), all routine replicate samples, including those for field spikes, are obtainedsequentially for each National Water Quality Laboratory (NWQL) schedule or laboratory code. Replicate samples for filtered inorganics (FA, FCC, FU, and alkalinity)are collected after the first set of these samples are obtained, and with a second Quality Water Service Unit (QWSU) capsule.

GCV glass chilled volatile GCC glass chilled chromatograph SC (NWQL) schedule LC (NWQL) lab codeHCl (NWQL) hydrochloric acid CG change gloves mL milliliter mm millimeters

μm micrometers L liters N2(g) nitrogen gas lb/in2 pounds/square inch

PBW (NWQL) pesticide blank water FA filtered acidified FCC filtered chilled HNO3 (NWQL) nitric acidDIW deionized water FU filtered untreated RU raw untreated U UraniumRa Radium ASR analytical service request °C degrees Celsius ≤ less than or equal to]

________________________________________________________________________________________________________________________

Team Member A Team Member B

 _________________________________________________________________ _________________________

Sample type (SC, LC) Filtration Collect, by Quality-assurance Chemical Temporaryand order of collection filling checks or measures preservation storage____________________ _______________________________________________________________________ ___________________________1. Organic filtered

 and unfiltered• Volatile organics None 3, GCV, 40-mL amber, Avoid sample aeration when filling. Add 1 to 5 drops Sleeve and

(SC2090, SC2091, glass vials, sequentially; Replace vial if gas bubble appears HCl to each vial, and chill1or SC2092 with using Teflon tube to fill after capping. (Team Member B, re- record amount [onSC1306) each vial from its base check, immediately after preserving) field and ASR forms]

until overflow occurs

• Organic carbon CG, use tweezers, and place a 1, GCC, 125-mL, amber Do not include plastic filter separa- None Sleeve and

(SC2085) QWSU, 0.45 μm, 47-mm- bottle to neck base after tor, or flip filter over during removal chill1

diameter silver filter in cylin- first discarding the initial from package. Do not overpressurizeder. Fill with sample, cap, 25 mL of filtrate to filter cylinderand (outside of chamber) pres- waste (do not rinsesure-filter [N2(g), ≤15 lb/in2]2 bottle)

• Pesticides CG, use tweezers, and place a 1, GCC, 1.0-L, amber Prewet membrane with 10 - 20 mL None Sleeve and

(SC2001 or SC2010, NWQL, 0.7 μm, 142-mm- glass bottle for each SC of NWQL PBW. Do not fill bottle chill1SC2050 or SC2051)3 diameter, baked, glass-fiber after first discarding the beyond neck to reduce breakage if

filter in plate unit, prewet the initial 125 mL of filtrate sample volume expands on chillingfilter, close unit, and void air4 to waste (do not rinse

bottle)

64
Table 21. Collection order, processing, preservation, and field storage required for ground-water-quality and replicate samples for the National WaterQuality Assessment Program--Continued

______________________________________________________________________________________________________________

Team Member A Team Member B

 _________________________________________________________________ _________________________

Sample type (SC, LC) Filtration Collect, by Quality-assurance Chemical Temporaryand order of collection filling checks or measures preservation storage_________________ ________________________________________________________________ __________________________

2. Inorganic, filtered

• Trace elements CG, and attach QWSU 1, FA, 250-ml, clear, Invert capsule (arrow up), and tap to Add 1-mL ampoule In dry cooler,

(SC2703-FA) 0.45-μm, preconditioned prerinsed, poly bottle evacuate air while filling. Verify of HNO3 avoid extreme

Supor capsule filter with to neck base after a DIW is still in sample bottle from heat or coldflexible Teflon tubing, and 25-mL filtrate rinse office prerinse before use; otherwisevoid air3 from capsule. (include cap) replace bottle

• Major ions If possible, use same capsule 2, FA, 250-mL, clear, Verify DIW is still in each bottle Add 1-ml ampoule In dry cooler,

(SC2750-FA and as above, otherwise replace prerinsed, poly bottles from office prerinse before use; HNO3 to each avoid extremearchive) with another preconditioned to necks after 3, 25- otherwise replace bottle bottle, CG heat or cold

capsule in manner above. mL filtrate rinses on

each (include cap)

• Nutrients CG, and, if possible, use the 1, FCC, 125-mL am- Verify DIW is still in bottle from None Sleeve and

(SC2752-FCC) same capsule as above, other- ber, prerinsed, poly office prerinse before use; other- chill1

wise replace in manner above. bottle to neck base wise replace bottle

after 3, 25-mL filtraterinses (include cap)

• Major ions If possible, use same capsule 1, FU, 250-mL, clear, Verify DIW is still in bottle from None In dry cooler,

(SC2750-FU) as above, otherwise replace in prerinsed, poly bottle office prerinse before use; other- avoid extreme

manner above. to neck base after 3, wise replace bottle heat or cold

25-mL filtrate rinses(include cap)

• Alkalinity (ALK) If possible, use same capsule 1, FA, 250-mL, clear, Verify DIW is still in bottle from On basis of grab None

as above, otherwise replace prerinsed, poly bottle office prerinse before use; other- sample, pipette thein manner above. to top after 3, 25-mL wise replace bottle required volume of

filtrate rinses (include filtrate into 250-mLcap), and cap bottle beaker, titrate, and

record data5

65
Table 21. Collection order, processing, preservation, and field storage required for ground-water-quality and replicate samples for the National WaterQuality Assessment Program--Continued

________________________________________________________________________________________________________________

Team Member A Team Member B

 _________________________________________________________________ ____________________________

Sample type (SC, LC) Filtration Collect, by Quality-assurance Chemical Temporaryand order of collection filling checks or measures preservation storage_________________ _________________________________________________________________ ___________________________

2. Inorganic unfiltered

• Major ions None 1, RU, 500-ml, clear, prerinsed Verify DIW is still in bottle from None In dry cooler,

(SC2750-RU) poly bottle to neck base after 3 office prerinse before use; other- avoid extreme

25-mL rinses with raw sample wise replace bottle heat or cold.(include cap)

• Acid-neutralization None 1, FA, 250-mL, clear, prerinsed Verify DIW is still in bottle from On basis of grab None

capacity (ANC), poly bottle to top after 3, 25- office prerinse before use; other- sample, pipette therecommended mL rinses with raw sample wise replace bottle required volume

(include cap) into a clean, 250-mL

beaker, titrate, andrecord data5

3. Other Samples

• Trace elements CG, and attach precon- 1, FA, 1-L, clear, prerinsed, Verify DIW is still in bottle from CG, and add 2 HNO3 In dry cooler,

(1.0-L samples, for ditioned capsule in man- poly bottle to neck base for office prerinse before use, other- ampoules to each avoid extremeexample, U, and Ra) ner similar to that used each element after a 25-mL wise replace bottle bottle heat or cold.

for SC2703 above3 rinse of bottle and cap

• Tritium isotopes None 1, 1.0-L, clear, prerinsed poly Verify DIW is still in bottle from None In dry cooler,

bottle, filled to top after 3, office prerinse before use, other- avoid extreme25-mL rinses (include cap wise replace bottle. Leave no cold or heat.with conical insert) headspace in bottle

• Deuterium-Oxygen None 1, 125-ml, glass, amber Leave no headspace in bottle None In dry cooler,

isotopes bottle to top after 3, 25-ml avoid extreme

rinses (include cap with heat or cold.conical insert)

66
Table 21. Collection order, processing, preservation, and field storage required for ground-water-quality and replicate samples for the National WaterQuality Assessment Program--Continued

________________________________________________________________________________________________________________

Team Member A Team Member B

 _________________________________________________________________ ___________________________

Sample type (SC, LC) Filtration Collect, by Quality-assurance Chemical Temporaryand order of collection filling checks or measures preservation storage________________ _________________________________________________________________ ____________________________

3. Other, continued

• Radon (LC1369) Disconnect extension 1, radon scintillation vial, after Compare oil level in vial before use None Repack vial in

line to sample chamber, rinsing syringe barrel twice with to that in vial from another tube. shipping tube,attach radon-collection sample before injecting 10.0 mL Return vial unused to NWQL if oil wrap ASR formunit to manifold, partly of sample into vial at base of level is low. Create sufficient back- (with collectionclose valve on unit. mineral oil. Cap and shake 10 pressure in device to create easy with- time) aroundCheck all sample-wet- seconds. Note and record drawal of sample without degassing. tube, fix withted lines up to unit actual time on ASR form Void all air from syringe after second rubber band,for gas bubbles, and (comments-to-NWQL line) rinse before inserting syringe needle and place tubedislodge any by tapping into septum of device. Initially in resealablelines with hard object. withdraw 15 mL of sample, invert plastic bag.(Record on ASR form if syringe [needle up], void sample tobubbles reform before leave 10.0 mL in syringe barrel, resamples are obtained) insert needle (down) into vial to

collect

• Chlorofluorocarbons Modify setup to attach Three to five CFC vials filled Critical to avoid air entrainment or None; can be stored In partitioned

 (CFCs) CFC--collection unit according to procedures used sample degassing during collection indefinitely if not box to reduce

(Busenberg and Plum- by Busenberg and Plummer (See radon above) biologically active breakagemer, 1992) to manifold (1992)or pump tubing outlet

_____________________________________________________________________________________________________________________________________

1Glass containers are placed in foam sleeves, and chilled samples generally stored in ice. Desired temperature of chilled samples is 0 to 4 °C2Cylinder and nitrogen-gas filtration system are available from Hydrologic Instruments Facility (table 3, in this report).3Possible flow adjustment could be required to increase flow from filtration unit to about 0.1 gallon (500 mL) per minute.4Samples under schedules SC2010 and SC2051 require Study Unit to extract water samples and send extracts to NWQL (see section on Pesticide Solid-Phase

Extraction).

5Volume of filtrate and normality of titrant determined from grab sample taken near end of purge (table 20, in this report). National Field Manual (Radtke and

Wilde, in press) discusses incremental and Gran titration methods and calculations. For NWIS-I, recommend using parameter codes as indicated in appendix (fig. A8).

67
68

Field-team functions

The setup (fig. 2) used to purge the well is modified slightly for sample collection. The

short turbidity-collection line is replaced by an extension line that runs to the sample-collection

chamber. The flow, which has been passing through an instrumented flowthrough chamber, is

rerouted (for example, using the second three-way flow valve as shown in fig. 2) through this

extension line that is connected to the sample-collection chamber. The rate of flow through the

sample-collection setup is about 0.1 gal (500 mL) per minute.

In general, samples are obtained and, with one or two exceptions, processed (for example,

filtered) by Team Member A (table 21). Except for radon and chlorofluorocarbons, which require special collection equipment, and dissolved organic carbon, which requires a pressurized

filtration, samples are obtained (sample containers are opened, if necessary, final rinsed, filled,

and closed) only within the collection chamber. As each sample container is removed from the

chamber, it is set aside on a clean surface, and not handed directly to Team Member B. This

reduces the likelihood of contamination of Team Member A, the chamber, and subsequent samples, as collection continues.

In general, Team Member B, who has removed coveralls and work gloves, preserves (if

necessary) and temporarily stores samples (table 21). Team Member B also performs field

titrations.

Chemical preservation of NAWQA samples currently (1995) requires a single preservation

chamber (for NWQL hydrochloric and nitric acids). This chamber is separate from that used to

collect samples (table 3). During preservation, samples are opened, preserved, and closed in this

chamber by Team Member B.

Throughout the collection process, the field-team members frequently replace their gloves

at logical intervals to further reduce sample contamination (table 21, CG). If either one leaves

the collection or preservation areas to perform other tasks, gloves must be replaced before activities in these areas are resumed.

Near the end of the sample-collection process, field titrations (particularly when replicate

filtered (ALK) or unfiltered (ANC) samples are taken) generally will require most of Team

Member B’s time. Therefore, Team Member A often will complete the collection of all samples after that for ANC with little or no assistance (table 21).

Special considerations for selected sample types

With adequate training and preparation, collection procedures for most sample types require no more than a conscientious effort to rinse and fill a bottle in a clean setting to obtain highquality data. Situations arise, however, which necessitate processing samples simultaneously

with their collection, or which require modifications to the general field-equipment setup and

protocols described (table 21).

Filtered Samples. To obtain high-quality samples, care must be taken in the use of filter

units and to avoid overpressurizing these units. The NWQL aluminum plate filter (for pesticide
69

samples) is prepared in the collection chamber (table 21) and has a simple nipple fitting, which

is connected to the sample outflow orifice inside the sample chamber by a short piece of Teflon

tube. Air is evacuated from the plate unit using the trip valve on top of the unit as it is filled by

raw sample flow. After evacuating the air, the trip valve is closed. Initially, some filtrate is discarded before any samples are collected (table 21).

The sample for dissolved (filtered) organic carbon (DOC) is collected directly in the DOC

filter cylinder in the collecting chamber. The DOC cylinder subsequently is capped, removed

from the chamber, and the sample filtered under N2 gas at a low (15 lbs/in2 or less) internal pressure. (Pressures in excess of 15 lbs/in2 can be hazardous and can rupture the filter membrane and

invalidate the sample.)

Routine NAWQA 0.45-μm-filtered inorganic samples are obtained using the QWSU capsule filter (for inorganic samples). The capsule is preconditioned before use (see “Final Presampling Plans and Preparations”). The capsule nipples are attached to flexible Teflon lines,

which allow the capsule to be inverted (arrow on capsule denotes direction of flow) during its

final rinse and use. Inverting the capsule so that the flow is vertically upward while the capsule

initially fills with water, combined with tapping the side of the capsule several times while it fills,

forces most air out of the capsule. Purging most of the air from the capsule filter helps prevent

oxidation and possible precipitation of redox-sensitive analytes (for example, iron, manganese,

aluminum, and uranium) that would (negatively) bias filtrate concentrations. Procedures for filtering inorganic samples that require filters with 0.2-μm or smaller pores are described in an internal document (F.D. Wilde, U.S. Geological Survey, written commun., 1995--see footnote 1).

In some instances, filter clogging by fine sediment, or even finer colloids, could markedly

reduce the rate of sample flow through the filter units described. Field teams are not to increase

flow by forcing water through a filter unit under increasing pressure. Instead, either clean the

clogged unit (see “Decontamination of Field Equipment” below) and reinstall the cleaned filter,

or simply replace the clogged unit with a second filter unit of similar type. It is most efficient to

have a second unit available. A second capsule filter unit also is required for the collection of

replicate, filtered inorganic ground-water samples.

Radon and Chlorofluorocarbon (CFC) Samples. Collection of these samples occurs

outside the sample-collection chamber and requires modifying the sample collection setup--

replace the extension line from the flow manifold to the sample-collection chamber with the

appropriate collection device (fig. 2). In either case, sample extension and pump-reel lines are

inspected to determine if gas bubbles are forming inside the line, or if any air is being drawn into

the sample flow at any connection. If these lines are adequately insulated to prevent warming of

the sample flow and connections are air tight, bubbles generally are not present. The presence

of bubbles indicates possible degassing of radon and CFCs from sample flow or entrainment of

CFCs from air that enters loose connections. Initially, bubbles often can be dislodged and evacuated with sample flow by striking the extension or pump-reel line sharply with a hard, blunt

object. Connections can be tightened to prevent air entrainment. This, combined with backpressure created by partially closing the valve on the radon-collection unit or backpressure

created in the operation of the CFC collection unit, often will reduce degassing during sample

collection.
70

For radon samples, the collection unit valve is partially closed, the glass syringe needle is

inserted through the septum port of the unit, and the unit valve is further closed until there is sufficient backpressure to create an almost effortless withdrawal of water into the syringe. The

syringe is partially filled, withdrawn from the septum, inverted (needle up), and the water ejected

to waste. This syringe rinse is repeated at least one time. After the final rinse, and with the

syringe plunger completely depressed (no air or water in syringe barrel) the needle is reinserted

through the septum, and about 15 mL of sample are withdrawn slowly into the syringe barrel to

avoid suction and degassing. The needle is withdrawn from the septum, the syringe inverted

(needle up), and the sample slowly ejected to waste until only 10.0 mL remains in syringe barrel.

The syringe needle is tipped downwards, and the needle tip inserted into the mineral oil, and

to the bottom of the radon sample vial. The 10.0 mL sample is injected slowly, the syringe

removed, the vial firmly capped, and the actual time (in military format) of sample collection

is recorded (see appendix, fig. A10). If no replicate sample is taken, the vial is shaken for 15

seconds, repacked in tube, the tube capped, and the NWQL-ASR form (lab copy) for radon

(LC1369) is wrapped around the tube, secured with a rubber band, and the tube temporally stored

(table 21). If a replicate sample also is collected, the height of the oil levels in the two vials is

compared before either sample is collected and should be similar. If levels are noticeably different, return the vial with the low oil level to NWQL with a note explaining the problem.

Because it can take a considerable amount of time to set up and collect samples for chlorofluorocarbons (CFCs), they generally are the last samples collected at a well. As in the case

of radon, their collection requires that the sample-collection setup be modified. The CFC unit

used to collect samples (Busenberg and Plummer, 1992) replaces the extension line and samplecollection chamber, or the CFC unit can be connected directly to the portable pump outlet

(fig. 2). Before connecting the CFC unit, it is recommended that flow be routed through the

flowthrough chamber, and field measurements be taken to characterize conditions at the onset

of CFC sampling. The procedures for collecting CFC samples are described in Busenberg and

Plummer (1992).

Decontamination of Field Equipment

Decontamination is the cleaning process used to remove contaminants from equipment.

Sample-wetted equipment used by NAWQA is decontaminated after sample collection at each

well, preferably before the equipment dries. Decontamination is conducted in clean and protected environments (in field area, vehicle, or chamber) as is appropriate to the equipment being

cleaned. If this is not possible, the equipment is at least flushed and rinsed, preferably with a

low-phosphate detergent, followed by a clean water (DIW) rinse, before it is temporarily stored

for thorough cleaning at a later date and before it is reused to collect samples.

On the basis of NAWQA pilot studies, studies conducted by the Office of Water Quality,

and data reported from other sources, the decontamination protocols and procedures for

NAWQA (tables 22 and 23) generally are capable of removing a broad suite of contaminants

from equipment affected by (a) milligram-per-liter contaminant levels for metals and metal complexes, and (b) microgram per liter contaminant levels for pesticides and volatile organic compounds. The decontamination protocols and recommended procedures for NAWQA assume

equipment was (or will be) used to collect filtered and unfiltered samples for most analytes
71

(table 1). The actual efficiency of these protocols and recommended procedures to remove contaminants to below NAWQA method-detection or reporting levels can differ depending on the

type of equipment used, the solubility and concentration of the contaminant, and the length of

time equipment is exposed to the contaminant.

Table 22. Decontamination of small equipment used for sample collection

[Volumes of solutions used (detergent, deionized water-DIW, methanol, and final rinse water) depend on Study-Unit

equipment setup. DIW used for rinses must have a conductivity that does not exceed 1.0 microsiemens per centimeter

at 25 degrees Celsius. A 0.1- to 0.2-percent detergent solution is prepared by adding about 5 to 10 drops of detergent

concentrate to each gallon of DIW. CG indicates field-team members are to change to clean, powderless, latex or vinyl

gloves before proceeding. Latex gloves are used when handling methanol. DOC, dissolved (filtered) organic carbon;

VOCs, volatile organic compounds]

_____________________________________________________________________________________________

SMALL FIELD-EQUIPMENT CATEGORIES1

_____________________________________________________________________________________________

Equipment with nonmetallic Equipment with metal parts and Equipment with nonmetallic

parts (for inorganics only). for inorganics, but not exposed parts, and rinsed with methanol

Includes convoluted Teflon to methanol. Includes the DOC for organics. Includes pesticide

tubing used on capsule filter, filter unit, the short Teflon line filter unit, the short Teflon

turbidity sample vials, and with metal quick-connect used to tubes for VOC sample-collecfield-titration Teflon stir bars, obtain turbidity samples, and the tion and for attaching pesticide

glass beakers, volumetric radon-collection equipment-- filter unit to a sample-chamber

pipettes, graduated cylinders, syringe with metal leur-lock outflow port, tweezers, and the

and polyethylene bottle for fitting, syringe needles, and the short Teflon-metal hook-up

DECONTAMINATION ALK (ANC) sample sample-collection unit. line (without plastic gardenSTEPS BY CATEGORY collection. hose-threaded fitting to well).

________________________________________________________________________________________________________

1. PREPARATION For each equipment category, disassemble parts, and place them in a small, clean, colorless,

polypropylene basin dedicated to that category.

2. DETERGENT WASH Cover and fill parts in each basin with detergent, and let stand at least 10 minutes; then scrub each

part gently with a soft-bristled brush that contains no metal parts and is dedicated to that basin.

3. DIW RINSE Rinse each part thoroughly with DIW at least three times to remove detergent solution and any

particulate matter. Complete rinsing of equipment, and also rinse basin and brush, in one category,

and CG before proceeding to equipment in the next category. Place rinsed equipment on a noncontaminating surface dedicated to the equipment in that category, and loosely cover equipment to

prevent recontamination. Plastic sheets can be used for equipment in the first category; aluminum

foil can be used for equipment in the other categories. Complete decontamination step (5)

below for first two categories before proceeding with the methanol rinse (4) of

equipment in the last category).

4. METHANOL RINSE (Third equipment category only) CG (latex), wear safety glasses; in a well-ventilated area

free of open flames or sparks, rinse each piece of equipment at least three times with small amounts

of methanol from a Teflon squeeze bottle. Place each rinsed part on a clean, noncontaminating

surface (such as aluminum foil) and loosely cover rinsed parts (with foil sheet) to avoid recontamination. Rinse each part over the basin previously used for detergent and DIW rinse. Transfer used

methanol from this basin to a waste container after all parts are rinsed, and before drying parts.

5. DRY, INSPECT, CG and use a portable dryer, or air dry, each part, in clean area. After each part is dried, inspect it.

and STORE Replace chipped or cracked glassware, or scratched turbidity vials. Replace tubing if mold, mildew,

or imbedded sediment are present. Replace filter seals if cracked or severely crimped. Store equipment in the first category in two nested, resealable plastic bags, and that from other categories in

Teflon bags or wrap in aluminum foil and then place in a resealable plastic bag. ________________________________________________________________________________________________________

 1Field sensors are each thoroughly rinsed with DIW, blotted dry, inspected along with field meters, and (if necessary)

reconditioned and stored according to manufacturers’ recommendations.
72

Table 23. Decontamination of setup equipment used for sample collection

[Volumes of solutions used (detergent, deionized water (DIW), methanol, and final-rinse water) depend on the StudyUnit equipment setup used. DIW used for final rinse must have a specific conductance that does not exceed 1.0 microsiemens per centimeter at 25 degrees Celsius. For methanol-rinsed equipment, it also should be volatile-organiccompound-free and pesticide-free. A 0.1- to 0.2-percent detergent solution is prepared by adding about 5 to 10 drops

of detergent concentrate to each gallon of DIW. CG indicates the field-team members are to change to clean, powderless latex or vinyl gloves before proceeding. Use latex gloves when handling methanol.]

________________________________________________________________________________________________________

Exterior of portable pump intake Interior of pump intake and sample-wetted

DECONTAMINATION and pump tubing drawn from tubing1

; including that from reel, flow manifold,

STEP pump reel flowthrough chamber, and all extension lines

________________________________________________________________________________________________________

1. PREPARATION CG, raise intake from well, coil Place pump intake2 in clean standpipe.3 Route flow

tubing onto plastic sheet set to from pump intake through setup to sample chamber.

drain, or into plastic basin, and Temporarily attach one end of a Teflon return-flow

disconnect tubing at pump-reel line to the outflow tube in the sample chamber, and

that runs to remainder of setup. run the other end of this line back to the standpipe.

2. DETERGENT Pour detergent solution over Fill standpipe with detergent solution to level above

 WASH pump intake and tubing. Scrub pump intake. Begin pumping, and note the time

both gently with a soft-bristled when return-flow line has filled. Direct flow from

brush that has no metal parts. this line back into standpipe, and cycle detergent at

500 milliliters per minute for at least 5 cycles, or 10

minutes. At end of cycling, add more detergent to the

standpipe, route flow to partially fill field-instrument

flowthrough chamber and waste lines. Stop pump.

3. DIW RINSE CG, raise intake and tubing CG, rinse standpipe and intake, individually, at least

above sheet or basin, and rinse 3 times to remove detergent. Reroute flow back to

at least 3 times with DIW sample chamber, add DIW to standpipe, and pump,

to remove detergent and any without cycling, until grab samples from the open

particulates. Proceed to end of return-flow line (now directed to waste) indiinspection and storage (Steps cate DIW rinse is detergent free (no sudsing). Halt

No. 6 and 7). pump. Shake flowthrough chamber to suspend any

sediment, then drain detergent from this chamber and

waste lines. Add more DIW to standpipe, start pump,

route flow to the flowthrough chamber, and rinse

chamber several times to remove detergent. Repeat

for waste lines. (Flowthrough chamber and waste

lines are inspected and stored at this time, see below.

If methanol is not required, go to Step No. 5, FINAL

RINSE, second paragraph).

4. METHANOL None. (Detergent scrub Reroute flow to sample chamber, and put free end of

 RINSE4 considered effective for return-flow line near the methanol waste container.

cleaning exterior of pump CG, rinse intake and standpipe, individually 3 times,

intake and pump tubing.) place intake in standpipe, and, if possible, force air

into first several feet of pump tubing (to mark end of

DIW and beginning of methanol rinse.) Fill the stand

pipe with methanol to level above pump intake. Add

and pump at least 2 liters of methanol into setup. If the

setup storage is less than 2 liters, collect methanol

as it leaves from end of return-flow line in waste container. Halt pump. Put methanol left in standpipe

into waste container. Pump air if possible into tubing (to mark end of methanol). Proceed to final rinse.
73

Table 23. Decontamination of setup equipment used for sample collection--Continued ________________________________________________________________________________________________________

Exterior of portable pump intake Interior of pump intake, and sample-wetted

DECONTAMINATION and pump tubing drawn from tubing, including that from reel, flow manifold,

STEP pump reel flowthrough chamber, and all extension lines

________________________________________________________________________________________________________

5. FINAL RINSE) None CG, and DIW rinse standpipe and intake individual-

 (DIW) ly at least 3 times. Add and pump DIW through setup

to sample-collection chamber and out return-flow

line. On basis of air marking, line storage, and pump

rate, collect methanol from return-flow line as it is

forced out by final rinse. Pump at least an additional

0.1 gallons of DIW through setup for every 10 feet

of methanol-wetted tubing, including return-flow line,

to waste after used methanol is collected.

Disconnect sample chamber from manifold, discard

used chamber bag, DIW-rinse chamber frame, and

dry. Repeat above for the preservation chamber.

DIW rinse and dry exterior of extension lines and

flow manifold. Inspect and store each piece of

equipment as it is dried according to procedures

below.

6. INSPECTION Simultaneously dry, inspect, and Inspect to ensure flowthrough chamber and waste

recoil tubing on pump reel. Dry lines are free of sediment. Extensions lines also

with large, disposable, lint-free are inspected for stains, cuts, or serious abrasions.

towels. Check for stains, cuts, and sediment. The flow manifold also is checked

or abrasions, and repair or replace for stains or sediment, and to ensure valves and

as necessary. Check and repair quick-connect fittings are in good working order.

pump intake and antibacksiphon Repair or replace as necessary to eliminate any

for loose or missing screws. problems.

7. STORAGE Except for pump intake and suf- Store flowthrough chamber, waste lines, looped and

ficient pump tubing to place in- recoupled extension lines, and flow manifold in clean

take in standpipe, cover the pump plastic bags. Place pump intake inside Teflon or other

reel and recoiled tubing with a noncontaminating bag, and then under material used

clean, plastic sheet or bag or other to cover pump-reel assembly. Fit sample and presernoncontaminating material. Clean vation chambers with clean bags. Unless field blanks

pump intake as described on right. are taken, store equipment in vehicle for transport.

________________________________________________________________________________________________________

1

 Before their initial use, all sample lines are acid washed to remove oils and other manufacturing residues. (See

table 3.)

2 Pump intake and reel tubing are that used on-site to collect samples. For a hook-up connection that attached setup

to a garden-threaded-hose valve on a water-supply pump, a small, portable pump, such as a Teflon diaphragm pump

head mounted on a 12-volt electric drive pump, or a valveless metering pump with a ceramic piston (for example, Fluid

Metering Instrument Model QB1-CSC or CSV) with 12-volt power can be used. Either pump is fitted with Teflon

convoluted or rigid-wall tubing (acid-washed when first obtained). The outflow tube from the pump is fitted with the

appropriate quick-connect to attach it to the extension line that ran from the hook-up connection to the flow manifold

(fig. 2).

3

 Standpipe is of sufficient height to supply necessary head for pump intake to operate. For some pumps, such as

the Grundfos Redi-Flo2, this head requirement is critical. Standpipe also must not absorb methanol (table 3).

4 Performed when it is known or suspected that equipment was exposed to pesticides or volatile organic

compounds.
74

In general, decontamination by NAWQA field teams includes a low-phosphate, dilutedetergent wash and scrub of equipment, followed by multiple rinses with DIW (tables 22 and

23). A methanol wash also is used on selected equipment that is likely to have been contaminated by volatile organic compounds or pesticides.

Except for CFCs, the equipment required for decontamination, including that for safe handling of methanol, has been described (table 3). Decontamination of CFC sample-collection

equipment is to be done by the supplier of that equipment (Eurybiades Busenberg, U.S. Geological Survey, written commun., 1995).

During field decontamination of NAWQA equipment, it is essential that the cleaning solutions used be completely removed as part of the decontamination process before equipment is

reused. The residual presence in sample-collection equipment of detergent and methanol can

bias some measurements. Reports of organic carbon samples being affected by residues of detergent and methanol have been verified. Removal of methanol and detergent from pump-reel

lines or the purge and collection setup (fig.2) requires that adequate volumes of rinse water are

passed through these lines. Study Units can calculate the storage volume of these lines (table

24). The sample-collecting setup storage volume is not only useful in estimating the amount of

dilute detergent and DIW needed for decontamination, but also is needed to determine the volume of high-purity water needed for field blanks.

Ideally, the final rinse water after the methanol rinse (table 23) should not contain detectable quantities of the analytes of interest. Study Units need to ensure that rinse-water composition does not lead to equipment contamination that can ultimately compromise the interpretation

of the water-quality data.

To obtain the suitable quality of DIW final rinse water for methanol-rinsed equipment,

ASTM Type 1 DIW is passed through a charcoal filtration system, stored in noncontaminating

containers under noncontaminating conditions, and periodically analyzed to ascertain that it is

free of the compounds of interest at the method detection limit. Alternatively, NWQL volatileand pesticide-free blank water (VPBW) can be used for the final DIW rinse.

Decontamination of equipment exposed to high concentrations of contaminants (for example, VOCs in excess of 10 μg/L) could require procedures that are more rigorous than the protocols and recommended procedures described here and involve cleaning agents that differ from

those commonly used (such as hexane). Whatever procedures are used, they must be documented by the Study Unit. This enables the National Program to identify potential problems and modify procedures accordingly. Questions regarding equipment decontamination and the use of

other decontamination procedures can be directed to the NAWQA QA Specialist.
75

Table 24. Estimation of decontamination solution volumes for standpipe and sample-wetted

tubing

_____________________________________________________________________________________

The storage volume, Vs, of a set of pump-reel and extension lines can be estimated as follows:

Vs = [(Lp x Cp) + (Le x Ce)] + [Csp x Vsp]

where Vs is storage volume, in gallons

Lp is length of pump-line segment being cleaned, in feet

Le is length of extension lines, in feet

Cp (or Ce) = 0.023 gallons per foot for a 3/8-inch internal-diameter (ID) line

or = 0.041 gallons per foot for a 1/2-inch ID line

Csp = 0.264 gallons per liter,

Vsp is volume of solution needed to fill standpipe to minimum level required to

operate pump, in liters.1

Examples:

Given: (1) Lp; the sample-wetted line segment is 100 feet for a pump-reel system that has

a 1/2-inch ID line;

(2) Le; two 10-foot, 3/8-inch ID extension lines, one running from the pump-reel

 outlet to the sample collection chamber, and another running from the

chamber back to the pump-reel (return-flow line to standpipe), and

(3) Lsp; that the minimum volume of solution required in the standpipe to operate

the pump is 0.8 liter.

(A) Estimate the volume of detergent solution needed for the detergent wash cycle.

Answer:

 Vs= [(100 x 0.041)+ (20 x 0.023)] + [0.264 x 0.8] = 4.87 gallons

(B) Estimate volume of District deionized water needed to displace detergent solution.

Answer: Vs, ideally.2

(C) Estimate volume of high-purity water needed to displace 2 liters of methanol just pumped

into the system.

Answer: Vs, ideally.3

_____________________________________________________________________________________ 1The minimal volume is that which corresponds to a level of solution in the standpipe which, if

maintained, allows the pump to operate without entraining air into flow. Once this level is reached,

remove pump and measure this volume.

2Estimate assumes no mixing of the two solutions and ignores potential for detergent to adhere to

tubing walls. As a general rule, it is recommended that outflow from end of return-flow line be checked

for sudsing to determine when detergent has been removed.

3Estimate assumes no mixing at the interface of the two solutions and ignores potential for methanol

to adhere to tubing walls. As a general rule, it is recommended that an additional 0.1 gallons (~ 0.4 liters)

of high-purity water for each 10 feet of pump and extension line used be displaced from sample-wetted

lines (pump-reel line-to-sample chamber) to remove methanol residues. Thus in the example above,

another 0.2 (= [(100 + 10) x (0.1/20)]) gallons (4 L) of DIW would be pumped from the system. This

implies a total of about 6.1 (= 4.9 + 1.2) gallons (24 L) of water would be used to remove methanol from

the setup equipment.
76

Preparation of Blank Samples

To verify that decontamination is adequate, field and possibly other blanks are prepared at

selected well sites in each ground-water component (see “Routine Quality-Control Samples:

Type, Number, Site Selection, and Timing”; and appendix, figs. A13 (A,B), A14, A18, and

A19). These field blanks are collected immediately after the equipment that was used to collect

samples at the well has been decontaminated. Methods used to obtain, process, preserve, temporarily store, and analyze field blanks (table 25) generally are similar to those used for corresponding ground-water samples (table 21). With the exception of trace-element field blanks,

field blanks are analyzed using the same NWQL schedules used to analyze ground-water-quality

samples.

Study Units are required to use specific types of water for field blanks (table 3). Generally,

NWQL VPBW is required for VOC field blanks, and either NWQL VPBW or NWQL PBW is

required for pesticide field blanks. Field blanks for dissolved organic carbon are obtained using

either NWQL water types, but a DOC source-solution blank also must be taken (table 25, footnote 3; and appendix, fig. A14). The QWSU IBW is required for trace-element, major-ion, and

nutrient field blanks. These blank solutions are analyzed regularly (by lot number) by the

NWQL to certify that they are free of measurable concentrations of NAWQA analytes. Lot numbers are recorded by the field team as part of the required data record for NAWQA field, solution, and trip blanks (see appendix, figs. A13, A14, and A19).

Except for trace elements, all field blanks are analyzed using the analytical NWQL schedule or laboratory code used for the corresponding ground-water-quality samples. For traceelement field blanks, NWQL schedule SC172 and laboratory codes LC0112 (As) and LC0087

(Se) are used in lieu of SC2703 to obtain concentration data at method detection limits (equal to

or in excess of 0.1 μg/L).

Preparation of Other Routine Quality-Control Samples and

Field Extracts of Pesticide Samples

As part of their data-collection activities, field teams will sometimes need to obtain, prepare, or process selected types of samples at some sites on the basis of required routine QC sampling for each ground-water component (for example, table 12). For example, the field team

occasionally will collect replicate ground-water-quality samples at selected wells and field spike

these samples with known amounts of selected VOCs or pesticides. If VOC samples are being

collected for a Study-Unit (or Subunit) Survey or Land-Use Study, spiked VOC ground-water

samples are required at selected sites. The field team also will submit at least one trip blank per

field season for VOCs from the field. If pesticide ground-water samples are being collected, pesticide field spikes are required. The field team also has the option of either extracting pesticides

(under NWQL schedules SC2010 and SC2051) from spiked or unspiked ground-water samples,

or sending these water-quality samples to the NWQL for extraction (under NWQL schedules

SC2001 and SC2050). Finally, if trace-element samples (SC2703) are collected, the field team

will send three standard reference samples per field season from the field to the NWQL for analysis. Each of these activities requires that special equipment be used, or that specific procedures

be followed (described below). It is strongly recommended that field spikes, solid-phase extraction, and the preparation of trip-blank and reference samples be done after all ground-water samples have been collected, equipment has been decontaminated, and (if applicable) field blanks

have been collected.
77

Table 25. Field-blank sample-collection protocols and procedures for ground-water components

of the National Water-Quality Assessment Program

[DIW, District deionized water with specific conductance less than 1.0 microsiemens per liter; NWQLVPBW, National Water Quality Laboratory volatile organic and pesticide-free blank water; NWQLPBW, pesticide-free blank water; QWSU-IBW, Quality Water Service Unit inorganic-free blank water;

DOC, dissolved (filtered) organic carbon; gal, gallons; L, liters; ~, approximately]

_____________________________________________________________________________________

1. Assumptions: Equipment just used to collect ground-water samples has been decontaminated

and, except for the pump intake being in a standpipe, is set up on site in the same manner as it

was for the collection of ground-water samples.

2. Determine Blank-Solution Types and Volumes Required1: _____________________________________________________________________________________

Minimum

Field blank(s) Required blank- volume Required procedure

collected solution type in gal (L)

_____________________________________________________________________________________

VOCs and DOC2 NWQL-VPBW 1.5 (~ 6) Waste 0.5 gal, then collect field

or pesticides NWQL-PBW blanks; can use DIW to force

and DOC last of VPBW or PBW water

through the system.

VOCs, DOC, NWQL-VPBW 2.0 (~ 8) Waste 0.5 gal, then collect field

and pesticides blanks; can use DIW to force

last of VPBW or PBW water

through the system.

Major ions, and QWSU-IBW 1.0 (~ 4) Waste 0.5 gal, then collect field

nutrients, or blanks; can use DIW to force

trace elements last of IBW water through the

system.

Major ions and QWSU-IBW 1.5 (~ 6) Waste 0.5 gal, then collect field

nutrients, and blanks; if necessary, use DIW to

trace elements force last of IBW water through

the system.

Combinations of NWQL-VPBW or 1.5 to 2.0 Waste 0.5 gal of the VPBW or

organics and in- NWQL-PBW and PBW water, then collect organic

organics above QWSU-IBW 1.0 to 1.5 field blanks; can use the IBW water

to force the VPBW or PBW water

through the system; waste 0.5

gal of IBW water, then can collect

inorganic field blanks using DIW

to force IBW water through the

system.
78

Table 25. Field-blank sample-collection protocols and procedures for ground-water components

of the National Water-Quality Assessment Program--Continued

_____________________________________________________________________________________________

3. General Field-Blank Collection Procedure--The procedure for collection of blanks assumes organic (VOC--SC2090, SC2091, or SC2092, Pesticide--SC2001 or SC2010 and SC2050 or SC2051,

and DOC--SC2085) and inorganic (Trace-element--SC2703, Major ion--SC2750, and Nutrient--

SC2752) field blanks are collected. This is the most complex type of field-blank collection.3

• Divide Field-Team Duties--Recommend that a three-person team be used. The standard twoperson field team collects samples in a manner similar to that used to collect ground.-water samples;

the third person adds blank water(s) to standpipe, and controls flow through system as needed to

facilitate field-blank collection.

• Check Flow Setup--from standpipe to sample collection chamber (fig.2), ensure that adequate volumes of DIW and the required blank water(s) are arranged in order and within easy reach of person

stationed at standpipe.

• Set Low Flow Rate--Once pumping is initiated, set flow (on basis of measurement at chamber outflow) to about 0.1 gal. (500 mL) per minute or less to avoid wasting excessive amounts of blank

water.

• Route blank solutions in presorted manner--As solutions are changed, pump operator should change

to clean gloves, empty residual solution from standpipe, and rinse pump intake and standpipe, individually, at least three times each, with the next solution, and attempt to pump air segment into pump

line before adding next solution to standpipe to mark change in solution type.

If air segment cannot be used to mark end of one solution and beginning of next, then the change in

solutions is determined solely on the basis of the storage volume in lines (table 24) divided by the

pumping rate (estimated above) to determine the time it takes for the solution to travel from the

standpipe to the outflow chamber. Once pump is started, and this time has elapsed, it is assumed

the correct solution is flowing from chamber outflow.

Regardless of whether air segments or timed flow or both are used to assess when the desired

solution arrives at the chamber, 0.5 gal (~ 2 L) of the solution are passed to waste before the field

blanks that require that water type are collected.

To limit the amount of blank water used, and left standing in pump-reel or extension lines after all

samples that require that blank-water type have been collected, one type of water can be used to

force the last of another type from the lines and to the chamber for collection.

• Collect field blanks in prescribed manner --The order, manner, and quality-control measures and

checks associated with obtaining, processing, preserving, and temporarily storing field blanks are

identical to the order, manner, and quality-control measures and checks that would be used to collect

a corresponding set of ground-water-quality samples (see table 21).
79

Table 25. Field-blank sample-collection protocols and procedures for ground-water components

of the National Water-Quality Assessment Program--Continued

_____________________________________________________________________________________________

4. Break Down Equipment Setup--After field blanks have been collected, equipment is broken down

and stored, accordingly (see tables 22 and 23). Exceptions include filter units using filter membranes that are removed and discarded, and the sample preservation chamber. If filters for organics

(pesticides and DOC) were used, the units are opened and filters discarded. Units are final rinsed,

reassembled and stored (see table 22, step 5, and table 23, step 7). The sample-preservation chamber

also is decontaminated before it is stored.

____________________________________________________________________________________________

1If portable pump was used, the same pump and length of pump line used to collect ground-water samples is

decontaminated and used to obtain field blanks.

2Note that VPBW and PBW are not certified free of organic carbon. A solution blank of that lot of water used

for the DOC field blank is sent to the NWQL for DOC analysis (see footnote no. 3 below).

3NWQL-PBW cannot be used for VOC field blanks. Either NWQL water type can be used for DOC field blank,

but both water types contain about 0.1 mg/L of organic carbon. A solution blank sample of water from the same lot

of NWQL water used for DOC field blank, poured directly into DOC 125-mL amber sample bottle) is required for

every DOC field blank. The lot number of the water used for the solution blank is recorded on the ASR form (see

appendix, fig. A14).

4With one exception, samples are analyzed using NAWQA schedules. The exception is trace-element field

blanks, for which the low-level NWQL blank schedule (SC172 with laboratory codes added for arsenic and

selenium) is recommended (see appendix, fig. A18).
80

Pesticide and volatile-organic-compound (VOC) spiked samples

Required equipment and procedures to spike ground-water samples in the field are obtained from the NWQL in kits prepared for the NAWQA Program (table 3). Training in field

spiking is required, and can be obtained through the basic course required for NAWQA groundwater field teams (table 6). Because of the need for recovery and variability data on field spikes

for the National Program, Study Units that wish to modify spike equipment or procedures as described below, or in NWQL kits for the NAWQA Program, by using different spike solutions or

volumes for routine QC spiked samples, are to discuss their plans with the National Program

(NAWQA QA Specialist).

At each site where pesticide field spikes are scheduled, at least three 1.0-L ground-water

sample bottles are required for each NWQL pesticide schedule (SC2001 or SC2010 and SC2050

or SC2051). These samples are collected sequentially during the collection of ground-waterquality samples and chilled (table 21). One bottle for each schedule serves as the ground-waterquality sample for the well. It also serves as a background sample (to determine what pesticides,

if any, were present in the other two sample bottles before they were spiked). The other two sample bottles are used for replicate field spikes. Each of these is spiked with 100 μL of NWQLpesticide-spike solution.

Currently, for VOC field spikes (SC2090, SC2091, or SC2092), at least seven sample vials

of ground water are collected sequentially and chilled (table 21). Three vials are needed for the

ground-water-quality sample, which also is the background sample for the field-spiked samples.

Replicate, field-spiked VOC samples (consisting of two vials each) are prepared by spiking each

vial with 100 μL of NWQL-VOC-spike solution.

In general, all samples (pesticide or VOC) are spiked with 100 μL of spike solution, which

results in a concentration of about 1 to 3 mg/L, depending on the analyte. If the background sample concentration of the analyte (in the unspiked sample) exceeds about one-tenth the concentration in spiked samples, the recovery data from spiked samples generally is considered positively

biased (dependent in part on the amount of analyte present before spiking). Use of a volume of

spike solution in excess of 100 μL, or a spike solution with higher concentrations than that commonly prepared by the NWQL, could reduce the bias. Recovery data from the use of such a spike

solution, however, will relate only to the high, and not the low, concentrations of the analyte.

Once prepared, field-spiked samples are chilled to 0 to 4°C, and generally treated in a manner identical to that of the corresponding background sample. Important information that relates

to the spiked sample (lot number, volume, and source of spike solution) are recorded on field

and NWQL ASR forms (appendix, fig. A12).

Pesticide solid-phase extractions

The option is available for Study Units to extract pesticides from ground-water-quality

samples (unspiked and spiked) or field blanks in the field, rather than having extractions done at

the NWQL. Extracts are collected on solid-phase cartridges and sent to the NWQL for analysis

under SC2010 and SC2051. Extraction equipment and procedures, prepared by the NWQL for
81

NAWQA, can be obtained from HIF or NWQL (table 3). Training in the extraction procedure

is required, and is obtained through the basic course required for NAWQA ground-water sampling field teams (table 6).

The decision to submit solid-phase extracts instead of water samples to the NWQL requires

careful consideration. Field extractions are practical and should be considered in situations

where transporting glass bottles, shipping weights, or shipping times pose a serious problem.

Extraction is recommended if pesticide water samples (for SC2001 and SC2050) cannot be

shipped and reach the laboratory within 72 hours after collection, or when information is available that indicates the analytes of interest could degrade rapidly during transit. Field extractions

also are recommended if the transportation of large, glass, sample bottles, or the sheer weight of

water samples, poses a hazard for the samples or the field team (for example, if wells are located

in remote areas that are accessible only by foot or light plane).

For Study Units that require a quick turnaround time on analytical results, sending field

extractions rather than water samples, particularly at peak production times at the NWQL, could

expedite data returns. The Study Unit should contact the NWQL in advance of adopting this

strategy, however, as there may be no backlog in analysis. In addition, special handling to

expedite analysis can be arranged with the NWQL at an additional cost.

Sending field extractions instead of water samples has another potential benefit. Field extractions allow the field team to extract less than a liter of sample, which is useful if water samples are known or suspected to contain concentrations that exceed the linear operating range of

NWQL methods (currently about 100 μg/L). In such cases, a measured (by weight difference)

sub-volume of the original 1-L water sample can be extracted. As an alternative, however, the

field team can request that the NWQL extract only part of a water sample (use comment line on

NWQL ASR form), and thereby achieve the same results.

Field extractions can reduce the costs of NWQL analysis and overnight shipping, particularly if the Study Unit is some distance from the NWQL. Whether or not sending field extractions instead of water samples is cost effective depends on whether or not the reduced costs in

analysis and shipping are less than the cost of obtaining, using, and maintaining extraction equipment and related supplies. The cost and time of labor associated with extracting samples also

should be factored into the decision. A 1-L sample typically requires one field-team member

about 45 minutes to extract, not including the time and labor cost needed for equipment assembly

and decontamination. Overall, Johnson and Swanson (1994) found laboratory processing required 32 percent fewer hours than on-site processing of extracts by a field team for each of two

prototype sites in the Central Nebraska Study Unit.

The time involved to set up equipment, conduct the extraction, and decontaminate, disassemble, and store this equipment can make it difficult for a two-person field team to perform extractions on-site at every well, given all the other on-site activities that the field team typically

is required to perform. Therefore, extractions usually are performed after most other on-site activities are completed. Alternatively, extractions can be performed by a third person, perhaps

off-site at a designated facility. This is probably the only practical method to field extract numerous pesticide samples in the field. For example, each routine QC site for pesticides requires
82

a minimum of six field extractions (one 1-L ground-water sample, plus two 1-L spiked groundwater samples for each of the two pesticide schedules).

VOC trip-blank and trace-element standard reference samples

Two types of routine QC samples require no sample collection, but are routinely sent from

selected sites in the field--the VOC trip blank and the standard trace-element reference sample

(table 10). Neither is ever opened by Study Unit personnel.

The VOC trip blank can be found in the box in which NWQL VOC vials are shipped.

When shipped by the NAWQA team from the field, the lot number (if not on the vial) can be

found on the box, and is recorded on the NWQL ASR form sent with the vial (appendix, fig.

A15).

Each Study Unit that conducts trace-element sampling in a given field season must request

three standard trace-element reference samples from the BTD&QS (table 10). These reference

samples are sent from different ground-water sites by the field team during that field season. At

each site, the field team records on the NWQL ASR form the original sample identification code

found on each bottle and relabels the bottle with the site identification code (appendix, fig. A19)

before the sample is shipped.

 Handling and Shipping of Samples

Handling and shipping protocols divide ground-water-quality and routine QC samples collected at a well into three groups (table 26). One group requires samples be shipped overnight

at less than 4°C. Another group can be shipped by surface (first class) mail at an ambient temperature. The third group is stored by the Study Unit, and possibly shipped for analysis at a later

date by surface mail.

To ensure that the samples collected will provide the data desired, the field team verifies

that all sample containers required from the well are present, and that all the information required

on container labels and field, NWQL-ASR, and other forms, is complete. It is important that the

containers are properly labeled, and that all forms contain the information needed by the NWQL

and the Study-Unit data manager (see appendix).

Samples that require overnight shipping (table 26, Group One) can undergo physical, biological, or radiochemical transformation or degradation within a short period of time. This is

reflected in their maximum holding times (elapsed time between sample collection and analysis). The maximum holding time for Group One samples is 3 to 5 days, except for VOCs, which

have a 14-day holding time. Holding times for most of these samples are dependent on maintaining low sample temperature (less than 4°C). During the period when most samples are being

sent to the NWQL (about April through October), at least half the holding time can expire after

these samples reach NWQL login and before they are analyzed. Thus, all of these samples must

be shipped without delay. In addition, and except for radon, these samples also must be packed

in a sufficient amount of ice to maintain low temperatures until received at NWQL and refrigerated.
83

Table 26. Sample handling for shipment of ground-water-quality and quality-control samples

[°C, degrees Celsius; lbs, pounds; mil, manufacturer bag thickness; SASE, self addressed and stamped

envelope; NWQL, National Water Quality Laboratory; ASR, Analytical Service Request; SC or LC,

NWQL schedule or laboratory code; FCC, FA, FU, and RU are bottle-type designations; CFC,

chlorofluorocarbon]

Sample Shipping Procedures

Group One:

Volatiles--SC2090, SC2091,

 and SC2092

Pesticides--SC2001 and SC2050

 or SC2010 and SC2051

Nutrients--SC2752-FCC

Organic Carbon--SC2085

(Add small (250-mL) polyethylene bottle filled with water

and labeled “For Temperature

Check, at Login.”)

Overnight at 0 to

4°C, and for safe

handling, at weight

less than 50 lbs.

Place samples in mesh bag and

place “Temperature Check”

bottle in middle of sample containers. Place a large, 4-mil plastic bag

in cooler, add layer of ice, and

place mesh bag on ice inside plastic bag. Surround and cover mesh

bag with ice, then twist and seal

outer plastic bag with waterproof

tape.

Radon--LC1369 Overnight (with

above or separate

from above).

Place resealable plastic bag containing radon tube(s) atop large

plastic bag above. Combine ASR

forms with Study-Unit Login reply

form and SASE in nested, resealable, plastic bags, and tape to

inside of cooler lid. Put return

address on inside of lid. Close lid,

secure it, and cooler drain cap with

strong tape. Attach air bill.

Group Two:

Major ions--SC2750--FA

 FU, and RU

Trace elements--samples

SC2703 (blanks--SC172)

Surface, first-class

mail, at ambient temperature and, for safe

handling, weight less

than 50 lbs.

Place trace-element samples in two

nested, resealable plastic bags and

place sealed bags in a heavy cardboard container; pack in bubble

pack, enclose forms (ASR and

login-reply forms, and SASE) in

nested, resealable plastic bags.

Seal container with strong tape and

attach mailing label with return

address.

Group Three:

Isotopes of tritium, deuterium,

and oxygen; major-ion (archive)

sample (SC2750--FA); and

possibly CFC samples

Initially archive in a

dry, cool, and clean

storage area; possibly ship (via regular

surface mail).

Archive individual samples in a

partitioned, heavy cardboard container. List sample types and date

on side of container. Also archive

ASR and any other forms.
84

To verify that low temperatures are maintained, each overnight shipment includes a small

(250-mL) polyethylene bottle filled with uncontaminated water (for example, deionized),

marked “For Temperature Check at Login.” This bottle is placed in the middle of the other samples being shipped. The NWQL login personnel will check the temperature of the water in this

bottle, record it on the Study-Unit’s “Login-Reply Return Form” (appendix, fig. A20), and return this form via the self-addressed and stamped envelope provided by the Study Unit. This

form and envelope initially are included with the NWQL ASR forms, which are double bagged

in resealable plastic bags, and taped to the inside of the shipping cooler (table 26). Study-Unit

data managers are to file the return forms, and keep a record of sample temperatures, particularly

those that exceeded 4°C.

 As a rule, water-quality samples with 3- to 5-day holding times should not be collected

on a Friday, particularly Fridays associated with 3-day weekends, because 3 to 5 days could

elapse before samples are analyzed. Radon, with a short half-life of approximately 3.6 days, is

definitely not collected if it cannot be shipped within 24 hours of collection and arrive at NWQL

login before 12:00 p.m. on any Friday.

Samples sent by regular surface mail (first class) have longer holding times than overnight

samples and do not need to be chilled (table 26, Group Two). It is recommended, however, that

these samples be shipped within a week or two of collection.

Samples archived by the Study Unit (table 26, Group Three) can include replicates (distinct

from those required for routine QC samples) of major ions (SC2750, FA bottle only), trace elements (for example, SC2703), isotope samples (for tritium, deuterium, and oxygen), and chlorofluorocarbon (CFC) samples. Archived major-ion and trace-element samples should be

discarded as soon as it is known that analytical reruns are not required. Isotope samples can be

held for several years provided bottles remain sealed. Samples for CFCs can be held for at least

several years, provided they are not biologically active (Eurybiades Busenberg, U.S. Geological

Survey, written commun., 1995).

REFERENCES CITED

Alley, W.M., ed., 1993, Regional ground-water quality: New York, Van Nostrand Reinhold, 634 p.

Alley, W.M., and Cohen, Philip, 1991, A scientifically based nationwide assessment of groundwater quality in the United States: Environmental Geology and Water Science, v. 17, no. 1,

p. 17-22.

Bachman, L.J., Shedlock, R.J., and Phillips, P.J., 1987, Ground-water-quality assessment of the

Delmarva Peninsula, Delaware, Maryland, and Virginia--Project description: U.S. Geological Survey Open-File Report 87-112, 18 p.

Busenberg, Eurybiades, and Plummer, L.N., 1987, pH measurement of low-conductivity waters:

U.S. Geological Survey Water-Resources Investigations Report 87-4060, 22 p.

Busenberg, Eurybiades, and Plummer, L.N., 1992, Use of chlorofluorocarbons (CCl3F and CCl2F2)

as hydrologic tracers and age-dating tools--the alluvium and terrace system of central Oklahoma: Water Resources Research, v. 28, no. 9, p. 2257-2283.
85

Christenson, S.C., and Parkhurst, D.L., 1987, Ground-water-quality assessment of the Central

Oklahoma aquifer, Oklahoma--Project description: U.S. Geological Survey Open-File

Report 87-235, 30 p.

Christenson, S.C., and Rea, A.H., 1993, Ground-water quality in the Oklahoma City urban area, in

Alley, W.M., ed., Regional Ground-Water Quality: New York, Von Nostrand Reinhold,

p. 589-611.

Cohen, Philip, Alley, W.M., and Wilber, W.G., 1988, National water-quality assessment--future

directions of the U.S. Geological Survey: American Water Resources Association, Water

Resources Bulletin, v. 24, no. 6, p. 1147-1151.

Ferree, D.M., Christenson, S.C., Rea, A.H., and Meander, B.A., 1992, Ground-water-quality

assessment of the Central Oklahoma aquifer, Oklahoma--Hydrologic, water-quality, and

quality-assurance data, 1987-90: U.S. Geological Survey Open-File Report 92-641, 193 p.

Gibs, Jacob, and Imbrigotta, Thomas, 1990, Well-purging criteria for sampling purgeable organic

compounds: Ground Water, v. 28, no. 1, p. 68-78.

Gilliom, R.J., Alley, W.M., and Gurtz, M.E., 1995, Design of the National Water-Quality Assessment Program--occurrence and distribution of water-quality conditions: U.S. Geological

Survey Circular 1112, 33 p.

Hamilton, P.A., Denver, J.M., Phillips, P.J., and Shedlock, R.J., 1993, Water-quality assessment

of the Delmarva Peninsula, Delaware, Maryland, and Virginia--effects of agricultural activities on, and distribution of, nitrate and other inorganic constituents in the surficial aquifer:

U.S. Geological Survey Open-File Report 93-40, 87 p.

Hamilton, P.A., Shedlock, R.J., and Phillips, P.J., 1992, Water-quality assessment of the Delmarva

Peninsula, Delaware, Maryland, and Virginia--analysis of available ground-water-quality

data through 1987: U.S. Geological Survey Water-Supply Paper 2355-B, 65 p.

Hardy, M.A., Leahy, P.O., and Alley, W.M., 1989, Well installation and documentation, and

ground-water sampling protocols for the pilot national water-quality assessment program:

U.S. Geological Survey Open-File Report 98-396, 36 p.

Hirsch, R.M., Alley, W.M., and Wilber, W.G., 1988, Concepts for a national water-quality assessment program: U.S. Geological. Survey Circular 1021, 42 p.

Johnson, S.M., and Swanson, R.B., 1994, Operational procedures for collecting water-quality samples at monitoring sites on Maple Creek near Nickerson and the Platte River at Louisville,

Eastern Nebraska: U.S. Geological Survey Open-File Report 94-121, 24 p.

Koterba, M.T., Banks, W.S.L., and Shedlock, R.R., 1993, Pesticides in shallow ground-water in

the Delmarva Peninsula: Journal of Environmental Quality, v. 22, no. 3, p. 500-518.

Koterba, M.T., Dysart, J.E., Phillips, S.W., and Zynjuk, L.D., 1994, Use and value of qualitycontrol data in studies in the Chesapeake Bay Region, in Proceedings of the National Symposium on Water-Quality, American Water Resources Association, Chicago, Ill., November

5-11, p. 65-74.

Koterba, M.T., Shedlock, R.J., Bachman, L.J., and Phillips, P.J., 1991, Regional and targeted

ground-water-quality networks in the Delmarva Peninsula, chapter 6, in Nash, R.G., and

Leslie, A.R., eds., Ground-Water Residue Sampling Design, American Chemical Symposium Series 465, American Chemical Society, Washington DC, p. 111-138.
86

Lapham, W.W., Wilde, F.D., and Koterba, M.T., in press, Ground-water data-collection protocols

and procedures for the National Water-Quality Assessment Program--selection, installation,

and documentation of wells, and collection of related data: U.S. Geological Survey OpenFile Report 95-398.

Leahy, P.P., Rosenshein, J.S., and Knopman, D.S., 1990, Implementation plan for the National

Water-Quality Assessment program: U.S. Geological Survey Open-File Report 90-174, 10 p.

Leahy, P.P., and Wilber, W.G., 1991, The National Water-Quality Assessment (NAWQA) Program--A basis for water-resource policy development: Irrigation and Drainage Proceedings,

July 22-26, 1991, IR Div/ASCE, Honolulu, Hawaii, p. 711-717.

Mattraw, H.C., Jr., Wilber, W.G., and Alley, W.M., 1989, Quality-assurance plan for the pilot

national water-quality assessment program: U.S. Geological Survey Open-File Report

89-726, 21 p.

Radtke, D.B., and Wilde, F.D., eds., in press, National field manual for collection of water-quality

data--Field measurements: U.S. Geological Survey Techniques of Water-Resources Investigations, book 9, chap. A6.

Rea, A.H., in press, Factors related to water quality in the Central Oklahoma aquifer, in Christenson, Scott and Havens, J.S., eds., Ground-water-quality assessment of the Central Oklahoma

aquifer--results of investigations: U.S. Geological Survey Open-File Report 93-441.

Reilly, T.E., Franke, O.L., and Bennett, G.D., 1989, Bias in groundwater samples caused by wellbore flow: Hydraulic Engineering Journal, v. 115, no. 2, p. 270-276.

Reynolds, G.W., Hoff, J.T., and Gillham, R.W., 1990, Sampling bias caused by materials used to

monitor halocarbons in ground water: Envrionmental Science & Technology, v. 24, no. 1,

p. 135-142.

Shampine, W.J., Pope, L.M., and Koterba, M.T., 1992, Integrating quality assurance in project

work plans of the U.S. Geological Survey: U.S. Geological Survey Open-File Report 92-

162, 12 p.

Smith, R.A. and Alexander, R.B., 1989, Reply To: Discussion by A.R. Russell and K.H. Coale on

“Trends in lead concentrations in major U.S. rivers and their relation to historical changes in

gasoline-lead consumption”: Water Resources Bulletin, v. 25, no. 6, p. 1279-1281.

van der Kamp, G., and Keller, C.K., 1993, Casing leakage in monitoring wells--detection, confirmation, and prevention: Ground Water Monitoring & Remediation, v. 13, no. 4, p. 136-141.

Welch, A.H., and Plume, R.W., 1987, Water-quality assessment of the Carson River ground-water

basin, Nevada and California--project description: U.S. Geological Survey Open-File Report

87-104, 27 p.
APPENDIX. EXAMPLES OF FIELD FORMS FOR THE COLLECTION OF

GROUND-WATER DATA AND SAMPLES FOR THE NATIONAL WATER-QUALITY

ASSESSMENT PROGRAM

Examples of field and analytical service request forms for the National Water Quality

Laboratory are provided in this appendix. Included are forms for the following:

A1. Land-use and land-cover field sheet for the 1991 Study Units, National Water-Quality Assessment

Program.1

A2. Example of quality-control and calibration form for the dissolved-oxygen sensor and meter.

A3. Example of quality-control and calibration form for the specific electrical conductance sensor and

meter.

A4. Example of quality-control form for a thermistor thermometer.

A5. Example of quality-control form for a pH sensor and meter.

A6. Theoretical slope values of Nerst equation for pH electrode (modified from Plummer and

Busenberg, 1981).

A7. Example of a purge form for a well.

A8. Example of a ground-water-quality sample-collection field form.

A9. Example of field-titration form.

A10-A. Example of an analytical service request form for primary ground-water-quality samples that

require overnight shipping.

A10-B. Example of an analytical service request form for primary ground-water-quality samples that can

be shipped surface (first class) mail.

A11-A. Example of an analytical service request form for replicate ground-water-quality samples that

require overnight shipping.

A11-B. Example of an analytical service request form for replicate ground-water-quality samples that can

be shipped surface (first class) mail.

A12-A. Example of an analytical service request form for replicate field-spiked, ground-water samples for

pesticides and volatile organic compounds: first set, TIME: HH:02.

A12-B. Example of analytical service request form for replicate field-spiked, ground-water samples for

pesticides and volatile organic compounds: second set, TIME: HH:03. (If optional third set is

taken, use a third form similar to the one above but with TIME: HH:04.)

A13-A. Example of analytical service request form for field blanks that require National Water Quality

Laboratory blank water and overnight shipping.

A13-B. Example of an analytical service request form for field blanks that require Quality of Water Service

Unit inorganic-free blank water (QWSU-IBW) and surface mail shipping.

A14. Example of an analytical service request form for dissolved (filtered) organic carbon (DOC)

solution blank composed of either NWQL volatile pesticide-free blank water (VPBW) or

pesticide-free blank water (PBW).

A15. Example of an analytical service request form for a volatile-organic-compound (VOC) trip blank.

A16. Example of an analytical service request form for a primary trace-element ground-water sample

(SC2703).

A17. Example of an analytical service request form for a replicate trace-element ground-water sample

(SC2703).

A18. Example of an analytical service request form for a ground-water trace-element (SC2703) field

blank.

A19. Example of an analytical service request form for a standard-reference trace-element (SC2703)

sample for ground water.

A20. Example of Study Unit login reply form sent with samples shipped by overnight mail.

1

Land-use and land-cover field sheet for the 1991 Study Units is being evaluated for use by the 1994 Study Units.

87
LAND-USE/LAND-COVER FIELD SHEET - GROUND-WATER COMPONENT OF NAWQA STUDIES - Page 1 (04/93)

1. NAWQA Study-Unit name using 4-letter abbreviation: ____________

Field-check date ___/___/___ Person conducting field inspection:__________________________________

Well station-id: ___________________ Latitude:__________________ Longitude:_______________________

2. LAND USE AND LAND COVER CLASSIFICATION - (modified from Anderson and others, 1976, p.8). Check all

land uses that occur within each approximate distance range from the sampled well. Identify the predominant land

use within each distance range and estimate its percentage of the total area within a 1/4-mile radius of the well.

3. AGRICULTURAL PRACTICES within 1/4 mile of the sampled well.

a. Extent of irrigation - Indicate those that apply.

Nonirrigated ____ Supplemental irrigation in dry years only ____, Irrigated ____

b. Method of irrigation - Indicate those that apply.

Spray ___ Flood ___ Furrow ___ Drip ___ Chemigation ___ Other ___ (Specify) ____________

c. Source of irrigation water - Indicate those that apply.

Ground water ____ Surface water ____ Spring __ __

Sewage effluent ____ (treatment): Primary ____ Secondary ____ Tertiary ____

d. Pesticide and fertilizer application - Provide information about present and past pesticides and fertilizers

used, application rates, and application methods._______________________________________________

_____________________________________________________________________________________

e. Crop and animal types - Provide information about present and past crop and animal types, and crop rotation

practices._____________________________________________________________________________

_____________________________________________________________________________________

 Entered by____________________ Date ___/___/___ Checked by __________________ Date ___/___/___

Figure A1. Land-use and land-cover field sheet for the 1991 Study Units, National Water-Quality

Assessment Program.

Land use and land cover

Within

100 ft

100 ft1/4 mi Comments

 I. URBAN LAND

--Residential

--Commercial

--Industrial

--Other (Specify)________

 II. AGRICULTURAL LAND

--Nonirrigated cropland

--Irrigated cropland

--Pasture

--Orchard, grove, vineyard,

 or nursery

--Confined feeding

--Other (Specify)________

 III. RANGELAND

 IV. FOREST LAND

 V. WATER

 VI. WETLAND

VII. BARREN LAND

Predominant land use

Approximate percentage of area

covered by predominant land use

88
LAND-USE/LAND-COVER FIELD SHEET - GROUND-WATER COMPONENT OF NAWQA STUDIES-Page 2 (04/93)

Well station-id: ______________________________ Field-check date: ____/____/____

 4. LOCAL FEATURES - Indicate all local features that may affect ground-water quality which occur within each

approximate distance range from the sampled well.

Figure A1. Land-use and land-cover field sheet for the 1991 Study Units, National Water-Quality

Assessment Program--Continued.

Feature within

100 ft

100 ft -

1/4 mi

Comments

Gas station

Dry cleaner

Chemical plant or

storage facility

Airport

Military base

Road

Pipeline or fuel

storage facility

Septic field

Waste disposal pond

Landfill

Golf course

Stream, river, or creek

Perennial __

Ephemeral __

Irrigation canal

Lined __ Unlined __

Drainage ditch

Lined __ Unlined __

Lake

Natural __ Manmade __

Reservoir

Lined __ Unlined __

Bay or estuary

Spring

 Geothermal (> 25 C)__

 Nongeothermal__

Salt flat or playa

Dry __ Wet __

Mine, quarry, or pit

Active __Abandoned__

Oil well

Major withdrawal well

Waste injection well

Recharge injection well

Other ______________

89
LAND-USE/LAND-COVER FIELD SHEET - GROUND-WATER COMPONENT OF NAWQA STUDIES -Page 3 (04/93)

Well station-id: ______________________________ Field-check date: ____/____/____

 5. LAND-USE CHANGES - Have there been major changes in the last 10 years in land use within 1/4 mile of

the sampled well? Yes __, Probably __, Probably not __, No __ If yes, describe major changes.

__________________________________________________________________________________

__________________________________________________________________________________

__________________________________________________________________________________

__________________________________________________________________________________

__________________________________________________________________________________

__________________________________________________________________________________

 6. ADDITIONAL COMMENTS - Emphasize factors that might influence local ground-water quality.

__________________________________________________________________________________

__________________________________________________________________________________

__________________________________________________________________________________

__________________________________________________________________________________

__________________________________________________________________________________

 Remarks

Figure A1. Land-use and land-cover field sheet for the 1991 Study Units, National Water-Quality

Assessment Program--Continued

90
Table 1: Model ____________________________; Serial Number (W) ____________________

Electrode Condition Calibration

Date Time Membrane

Membrane

changed

last

Gold

cathode

and silver

anode

Electrolyte Battery Red- line Zero

Meter1

temperature

(oC)

Saturated

DO at

temperature

(mg/L)

Atmospheric.

pressure

(mm Hg)

Correction

factor

Calibration

DO

(mg/L)

Adjusted

 (Y or N)

Initials

 of

testor

oC = degrees Celsius; mg/L = milligram per liter; mm Hg = millimeters of mercury1See temperature quality-control form for thermistor used with this instrument (fig. A4).Figure A2. Example of quality-control and calibration form for the dissolved-oxygen (DO) sensor and meter.

91
Table 1: Model _____________________; Serial number (W) ______________________

Condition of: Conductance calibration:

Date Electrode Meter Thermistor1

Standard

# 1

less

than 100

μS/cm

Reading

μS/cm

at

25oC

Within

5% of

standard

Standard

# 2

greater

than 100

μS/cm

Reading

μS/cm

at

25oC

Within

3%

of

standard

Initials

and

action

taken

1See thermistor form for quality-control tests on thermistor, all readings at 25o

 Celsius ( 25oC) in microsiemens per

centimeter (μS/cm).

Figure A3. Example of quality-control and calibration form for the specific electrical conductance

sensor and meter.

92
Table 2: Model ____________________ Serial number (W) __________________

 Low temperature (0 to 5oC) High temperature (15 to 35oC)

Date ASTM

thermometer1

reading (oC)

Meter

reading

 (oC)

Within

0.2oC?

ASTM

thermometer

reading (oC)

Meter

reading

 (oC)

Within

0.2oC?

Action

taken

Initials

1American Society for Testing and Materials (ASTM) thermometer, serial number _______________________.

Specify thermistor use by checking one below:

pH ____ Specific electrical conductance ____ Dissolved oxygen ____ Turbidity ____ Temperature _____

Figure A4. Example of quality-control form for a thermistor thermometer measuring degrees Celsius (oC).

93
Table 3:

Reading Reading

Date Low

pH

buffer

High

pH

buffer

mV

low

mV

high

pH

low

pH

high

Buffer

temperature

(

oC)

Actual

slope1

∆mV/

∆pH

Theoretical

slope at

temperature2

Slope

ratio3

(%)

Pass

(Y

or

N)

Response

time4

(seconds)

Initials/

action

taken5

1

Actual slope = ∆mV/∆pH, where ∆mV is difference in millivolt readings between low and high pH buffers, and ∆pH is difference in

measured pH (that meter locks on) between low and high pH buffers.

2

Theoretical slope of Nernst equation (see fig. A6) as function of buffer temperature in degrees Celsius (oC).

3Slope ratio in percent = (actual slope/theoretical slope) x 100. An acceptable ratio is one greater than or equal to 95.0 percent.

4Response time for meter to lock onto low pH buffer after calibration on high pH buffer. An acceptable value is less than or equal to

15 seconds.

5Initials of person performing quality control, and action taken by that person. See temperature quality-control form for thermistor used

with this instrument (fig. A4).

Figure A5. Example of quality-control form for a pH sensor and meter.

94
Table 4:

Temperature1 Theoretical slope2 Temperature Theoretical slope

0 54.197 21 58.364

1 54.396 22 58.562

2 54.594 23 58.761

3 54.792 24 58.959

4 54.991 25 59.157

5 55.189 26 59.356

6 55.388 27 59.554

7 55.586 28 59.753

8 55.784 29 59.951

9 55.983 30 60.149

10 56.181 31 60.348

11 56.380 32 60.546

12 56.578 33 60.745

13 56.777 34 60.943

14 56.975 35 61.141

15 57.173 36 61.340

16 57.372 37 61.538

17 57.570 38 61.737

18 57.769 39 61.935

19 57.967 40 62.133

20 58.165

1Degrees Celsius, record to nearest tenth of degree.

2Interpolate theoretical slope for buffer temperatures between whole degree values.

Figure A6. Theoretical slope values of Nerst equation for pH electrode at temperature

specified (modified from Plummer and Busenberg, 1981).

95
Table 5:

WATER-LEVEL MEASUREMENTS, PURGE VOLUME, AND FIELD MEASUREMENTS BEFORE SAMPLING

USGS I.D.: ________________________________ Date _____________________________ Time _____________________

Local Well I.D.: ____________________________ Field Team I.D.: __________________________

Well diameter (D, inches): _____________ Depth to water1

 (feet): ______________ Depth of well1 (feet):_______________

Height of water column (H, feet): ___________________ Casing (borehole) wetted volume (= 0.0408HD2

, gallons)

 ___________________________________________

Purge volume (= 3 x casing volume, gallons): _____________________ Pump type: ___________________________________

Time

(min.)

Pump

depth

(feet)

Pump

rate

(gpm)

Volume

pumped

(gal)

Water

appearance

(clear,

cloudy, etc.)

Temperature

(

o

C)

Dissolved

oxygen

(mg/L)

pH Specific

conductance

(μS/cm at

25oC)

Turbidity

(NTU)

Except for pH, median values of final 5 measurements; to

be used on ASR forms and field sample-collection forms

(fig. A9).2

min. = minutes; gpm = gallons per minute; gal = gallons; oC = degrees Celsius; mg/L = milligrams per liter; μS/cm at

25oC = microsiemens per centimeter at 25oC; NTU = nephelometric turbidity unit

1Reference datum was measurement point ___________________ Land surface datum (surveyed) _____________________

Equipment used _____________________________________________________ Accuracy _______________________

2For pH, after other final measurements are taken, temporarily divert flow and use final pH value obtained on standing water in

flowthrough chamber.

Figure A7. Example of purge form for a well.

96
LOCAL ID RECORD #

1

Station identification number Type Date Time

lat. long. seq. Y M D

1 2 16 17 18 23 24 27

Local Well Number Site Geologic Unit Hydrologic Unit

State District County

Sampled by ______________________

Location ___________________________________________________________________

*

4010 = thief sample

Yield when

sampling (GPM)

Code Value Remarks

00059

Minutes pumped 72004 before sampling

Sampling 82398 method

4020 = bailer

4030 = suction pump

4040 = submersible pump

4050 = squeeze pump

4060 = gas reciprocating

4070 = air lift

4080 = peristaltic pump

4090 = jet pump

4100 = flowing well

Sampling 72006 condition

0.10 = site was being pumped

0.11 = site had been pumped recently 4. = flowing

8. = pumping

30. = seeping

Code Value Remarks

Static water

level (feet) 72019

Altitude

lsd (feet) 72000

Depth to top

sample interval 72015

Depth to bottom

sample interval 72016

Finished well

depth (feet) 72008

Hole depth

(feet) 72001

pH

field 00400

Alkalinity 39086

Bicarbonate 00453

Carbonate

total field 00452

Acid neutralization capacity* 00419

Water

temperature

00010

Air 00020

Specific 00095

Dissolved

oxygen

00300

Turbidity 72008

temperature

conductance

total field*

total field

Bottles Filled Volume Treatment

___________

___________

___________

___________

___________

___________

_________

_________

_________

_________

_________

_________

_________

_________

_________

_________

_________

_________

Comments:

Quality-control samples taken?

Any land-use changes?

VOCs--acid used:

Was form updated?

Yes No

Yes No

Yes No

Drops to pH 2 Drops used

*For Gran-method titrations, values of Alk and ANC in

mg/L have parameter codes 29802 and 29813, respectively.

Figure A8. Example of a ground-water-quality sample-collection field form.

97
Table 1:

Units

of acid

pH ∆ pH ∆ units

acid

∆ ph/

∆ units

Units

of acid

pH ∆ pH ∆ units

acid

∆ ph/

∆ units

 Station identifier Date Time

Normality of acid Volume of acid to pH ~ 8.3

Type of titration Volume of acid to pH ~ 4.5

Incremental,

inflection point

ANC, mg/L CaCo3

a Comments:

Alk, mg/L CaCo3

b

Bicarbonate, mg/L HCO3

-

Carbonate, mg/L CO3

=

a

ANC - acid neutralizing capacity; on unfiltered

sample from inflection point at about pH = 4.5.

bALK - alkalinity, carbonate, and bicarbonate, on

filtered sample from inflection points at about pH =

8.3 and 4.5.

Figure A9. Example of field-titration form.

98
a

Use 7 if any replicate ground-water samples are taken for the above schedules or those on figure A10-B.

bIf 9 used for sample type, add all P-codes, including those under field values, except for 99105, which is left

blank. If 7 used for sample type, inlcude P code 99105. Also add P codes to QWDATA record for sample.

c

This is a priority message, must appear.

dOvernight shipping is recommended for all samples. Do not put radon tube in ice.

 Figure A10-A. Example of an analytical service request form for primary ground-water-quality samples

(including radon) that require overnight shipping.

99
a

Use 7 if any replicate ground-water samples are taken for the above schedules or those on figure A10-A.

bIf 9 used for sample type, add all P codes, including those under field values, except for 99105, which is left blank.

If 7 used for sample type, include P code 99105. Also add P-codes to QWDATA record for sample.

c

No comments; otherwise, priority comments on figure A10-A could be overwritten.

dRecommend samples be sent surface mail within 2 weeks of collection date.

Figure A10-B. Example of an analytical service request form for primary ground-water-quality samples that can

be shipped surface (first class) mail.

100
a

Add P codes noted above to form and to QADATA record for this sample.

bThis is a priority message, must appear.

c

Overnight shipping with primary samples (fig. A10-A) is recommended.

Figure A11-A. Example of an analytical service request form for replicate ground-water-quality samples

(including radon) that require overnight shipping.

101
a

Add P codes noted above to form and to QADATA record for this sample.

bNo comments; otherwise, priority comments on figure A11-A could be overwritten.

c

Surface (first-class) shipping with primary samples (fig. A10-B) is recommended.

Figure A11-B. Example of an analytical service request form for replicate ground-water-quality samples that

can be shipped surface (first class) mail.

102
a

Use indicated spiked-sample P codes; include in QADATA record for sample.

bInclude lot number of each spike vial used with each schedule.

c

Ship overnight with primary unspiked (background) ground-water samples (fig. A10-A).

Figure A12-A. Example of an analytical service request form for replicate field-spiked, ground-water samples

for pesticides and volatile organic compounds; first set, TIME: HH:02.

103
a

Use indicated spiked-sample P codes; include in QADATA record for sample.

bInclude lot number of each spike vial used with each schedule.

c

Ship overnight with primary unspiked (background) ground-water samples (fig. A10-A).

Figure A12-B. Example of an analytical service request form for replicate field-spiked, ground-water samples

for pesticides and volatile organic compounds; second set, TIME: HH:03. (If optional third set is taken, use a

third form similar to the one above but with TIME: HH:04.)

104
a

Add all P-codes to form and to QADATA record for sample.

bPriority comment, blank water lot number. If SC2090 not taken, NWQL pesticide-free blank water can be

used, and if it is used, change the P code 99100 to “40” and the comment to “NWQL PBW: lot no.”

c

Ship blank samples with corresponding ground-water-quality samples.

Figure A13-A. Example of an analytical service request form for field blanks that require National Water

Quality Laboratory blank water and overnight shipping.

105
a

Add all P codes to form and to QADATA record for this sample.

bPriority comment, must appear.

c

Recommend field-blank samples be shipped surface mail with corresponding ground-water samples

(see figs. A10-A,B).

Figure A13-B. Example of an analytical service request form for field blanks that require Quality of Water

Service Unit inorganic-free blank water (QWSU-IBW) and surface mail shipping.

106
a

Add all P codes noted to form and to QADATA record for this sample.

bIf DOC field blank (fig. A13-A) taken with NWQL PBW, instead of NWQL VPBW, change the P code 99100 to

“40” and the comment to “NWQL PBW: lot no.”

c

Priority comment, must appear in relation to blank water used (NWQL PBW or NWQL VPBW).

dThis DOC solution blank is shipped overnight with the corresponding DOC field blank (fig. A13-A).

Figure A14. Example of an analytical service request form for dissolved (filtered) organic carbon (DOC) solution

blank composed of either NWQL volatile pesticide-free blank water (VPBW) or pesticide-free blank water (PBW).

107
a

Add all P codes noted to form and to QADATA record for this sample.

bNWQL VPBW is assumed for trip blanks; priority comment, lot no. of VOC trip blank vials. c

Ship overnight with corresponding volatile ground-water samples collected in vials from same lot (fig. A10-A).

Figure A15. Example of an analytical service request form for a volatile-organic-compound (VOC) trip blank.

108
a

Add all P codes noted to form and to QADATA record for this sample.

bIf a replicate trace-element sample is collected (fig. A17), code sample type as 7; otherwise, code as 9.

c

Add labcodes for arsenic (LC0112) and selenium (LC0087).

dInclude field measurements (median values), particularly for specific electrical conductance (SC) at 25 degrees

Celsius (P code 00095), and note on comment line if SC exceeds 2,000.

e

Recommend sample be shipped surface mail with other primary inorganic samples (see fig. A10-B).

f

Only the FA sample bottle is required if Study Unit acidifies sample, provides field SC value, and indicates in

comment field if SC exceeds 2,000 microsiemens per centimeter at 25 degrees Celsius.

Figure A16. Example of an analytical service request form for a primary trace-element ground-water sample (SC2703).

109
a

Add all P codes noted to form and to QADATA record for this sample.

bAdd labcodes for arsenic (LC0112) and selenium (LC0087).

c

Include field measurements (median values), particularly for specific electrical conductance (SC) at 25 degrees

Celsius (P code 00095), and note on comment line if SC exceeds 2,000.

dRecommend sample be shipped surface mail with other primary inorganic samples (see fig. A10-B).

e

Only the FA sample bottle is required if Study Unit acidifies sample, provides field SC value, and indicates in

comment field if SC exceeds 2,000 microsiemens per centimeter at 25 degrees Celsius.

Figure A17. Example of an analytical service request form for a replicate trace-element ground-water sample (SC2703).

110
a

Add all P codes noted to form and to QADATA record for this sample.

bSC172 required for field blanks instead of SC2703--provides detection-level or higher concentration data.

c

Add labcodes for arsenic (LC0112) and selenium (LC0087).

dInclude priority comments; note that SC value is not given under the P code (this is blank water).

e

Recommend sample be shipped surface mail with other primary inorganic samples (fig. A10-B).

f

Only the FA sample bottle is required if the Study Unit acidifies sample and provides SC comment.

Figure A18. Example of an analytical service request form for a ground-water trace-element (SC2703) field blank.

111
a

Add all P codes noted to form and to QADATA record for this sample.

bAdd labcodes for arsenic (LC0112) and selenium (LC0087).

c

Include priority comments; note that SC value is not given under the P code (this is blank water). Specify

bottle code originally found on bottle as received from BTD&QS.

dRecommend sample be shipped surface mail with other primary inorganic samples (fig. A10-B).

e

Only the FA sample bottle is required if the Study Unit acidifies sample and provides the SC comment.

Figure A19. Example of an analytical service request form for a standard-reference trace-element (SC2703)

sample for ground water.

112
LOGIN REPLY SHEET

Date Mailed: __________________ Person sending shipment: ______________________

Place from which shipment was mailed: ___________________________________

Shipped via: _________________________________________________________

Type of Sample (circle one): ORG NUT PEST VOC RADON INORG

Station Numbers of Samples in This Shipment

____________________________________ __________________________________

____________________________________ __________________________________

____________________________________ __________________________________

____________________________________ __________________________________

____________________________________ __________________________________

LOGIN STAFF:

Please enter the following information on this form and mail the form back to us with the attached

self-addressed, franked envelope. Note that there is an 8-ounce bottle of tap water in this shipment marked

“TEMPERATURE” for use in measuring water temperature.

Person logging in shipment: ________________________________________

Date Shipment Arrived:

Water Temperature:

Comments (if applicable):

If you have any questions about this shipment, please contact:

Name: _________________________________________

Telephone: ( ) __________ - _______________

E-mail or Internet: _______________________________

Thank You For Your Participation in This Quality Assurance Program.

Figure A20. Example of Study Unit login reply form sent with samples shipped by overnight

mail.

113
Errata for Open-File Report 95-399

Corrections are by Michael Koterba; January 24, 1996

Page 16, Table 3, Footnote 21, Item (1)--change from:

 "For assistance with (1) isotope, radiochemical, and other specialized equipment, contact the NAWQA Quality

Assurance Specialist;"

to:

 "For assistance with (1) deuterium-oxygen isotopes, and quality-assured sample bottles and caps for these

isotopes, contact Tyler Coplen, Isotope Fractionation, USGS National Research Program, MS 431, Reston, Va.

(via isotopes@usgs.gov); for assistance with tritium isotopes, and quality-assured sample bottles and caps for these

isotopes, contact Robert Michel, Isotope Tracers, MS 434, USGS National Research Program, Menlo Park, Calif. (via

tritium@mailrcamnl.wr.usgs.gov);"

Page 66, Table 21, 3. Other Samples--Columns for Tritium isotopes and Deuterium-Oxygen isotopes change from:

 .

Team Member A

Sample type (SC, LC)

and order of collection

Collect, by

filling

Quality-assurance

checks or measures

• Tritium isotopes 1, 1.0-L, clear, prerinsed poly

bottle, filled to top after 3,

25-mL rinses (include cap

with conical insert)

Verify DIW is still in bottle from

office prerinse before use, otherwise replace bottle. Leave no

headspace in bottle

• Deuterium-Oxygen

 isotopes

1, 125-ml, glass, amber

bottle to top after 3, 25-ml

rinses (include cap with

conical insert)

Leave no headspace in bottle

to:

Team Member A

Sample type (SC, LC)

and order of collection

Collect, by

filling

Quality-assurance

checks or measures

• Tritium isotopes 1, 1.0-L, dry, high-densitypoly (preferred) or glass

bottle, without prerinsing,

until it overflows, and seal

with a cap with conical insert

To reduce breakage of glass

bottles caused by samples freezing during shipment, pour out

sample until the water level is at

the bottle shoulder seam.

• Deuterium-Oxygen

 isotopes

1, 60-mL, dry, clear, glass

(preferred) or poly bottle,

without prerinsing, until it

overflows, and seal with a cap

with conical insert

To reduce breakage of glass

bottles caused by samples freezing during shipment, pour out

sample until the water level is at

the bottle shoulder seam. Samples collected in poly bottles are

sent immediately for analysis,

and are unsuitable for archiving.