Evaluation of Well-Purging Effects on Water-Quality 

Results for Samples Collected from the Eastern Snake 

River Plain Aquifer Underlying the Idaho National 

Laboratory, Idaho

Scientific Investigations Report 2006–5232

Prepared in cooperation with the U.S. Department of Energy

U.S. Department of the Interior

U.S. Geological Survey

DOE/ID-22200
Cover: Photograph of U.S. Geological Survey well and equipment used to collect samples and 

containerize excess purge water at the Idaho National Laboratory, Idaho. View looking north.

(Photograph taken by Betty J. Tucker, U.S. Geological Survey, Idaho National Laboratory Project Office.)
Evaluation of Well-Purging Effects on 

Water-Quality Results for Samples 

Collected from the Eastern Snake River 

Plain Aquifer Underlying the Idaho National 

Laboratory, Idaho

By LeRoy L. Knobel

Prepared in cooperation with the U.S. Department of Energy DOE/ID-22200

Scientific Investigations Report 2006–5232

U.S. Department of the Interior

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

DIRK A. KEMPTHORNE, Secretary

U.S. Geological Survey

Mark D. Myers, Director

U.S. Geological Survey, Reston, Virginia: 2006

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Suggested citation:

Knobel, L.L., 2006, Evaluation of well-purging effects on water-quality results for samples collected from the 

eastern Snake River Plain aquifer underlying the Idaho National Laboratory, Idaho: U.S. Geological Survey Scientific 

Investigations Report 2006-5232, 58 p.
iii

Contents

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

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

Purpose and Scope ..............................................................................................................................3

Geohydrologic Setting .........................................................................................................................3

Previous Investigations........................................................................................................................5

Study Methods ...............................................................................................................................................5

Sample Collection Methods................................................................................................................5

Analytical Methods...............................................................................................................................6

Guidelines for Interpretation of Analytical Results.........................................................................6

Statistical Equivalency of Sample Pairs ..................................................................................6

Gross Radioactivity and Radionuclides ...................................................................................7

Non-radioactive Inorganic Constituents .................................................................................7

Organic Constituents.................................................................................................................13

Qualitative Evaluation of Well-Purging Effects on Water-Quality Results .........................................14

Quantitative Evaluation of Well-Purging Effects on Water-Quality Results.......................................15

Observations.................................................................................................................................................17

Summary and Conclusions.........................................................................................................................17

Acknowledgments.......................................................................................................................................18

References Cited..........................................................................................................................................18

Figures

Figure 1. Map showing location of eastern Snake River Plain, Idaho National

Laboratory, and selected wells, Idaho ................................................... 2

Figure 2. Map showing locations of selected wells near the Idaho Nuclear

Technology and Engineering Center and Central Facilities Area, Idaho ............ 4

Figure 3. Graphs showing water-quality data for well USGS 20, 1990-2003, with

corresponding data for October-November 2003, Idaho National

Laboratory, Idaho ........................................................................... 20

Figure 4. Graphs showing water-quality data for well USGS 34, 1990-2003, with

corresponding data for October-November 2003, Idaho National

Laboratory, Idaho ........................................................................... 21

Figure 5. Graphs showing water-quality data for well USGS 35, 1990-2003, with

corresponding data for October-November 2003, Idaho National

Laboratory, Idaho ........................................................................... 23

Figure 6. Graphs showing water-quality data for well USGS 36, 1990-2003, with

corresponding data for October-November 2003, Idaho National

Laboratory, Idaho ........................................................................... 24

Figure 7. Graphs showing water-quality data for well USGS 37, 1990-2003, with

corresponding data for October-November 2003, Idaho National

Laboratory, Idaho ........................................................................... 25

Figure 8. Graphs showing water-quality data for well USGS 38, 1990-2003, with

corresponding data for October-November 2003, Idaho National

Laboratory, Idaho ........................................................................... 26
iv

Figure 9. Graphs showing water-quality data for well USGS 39, 1990-2003, with

corresponding data for October-November 2003, Idaho National

Laboratory, Idaho ........................................................................... 28

Figure 10. Graphs showing water-quality data for well USGS 40, 1990-2003, with

corresponding data for October-November 2003, Idaho National

Laboratory, Idaho ........................................................................... 29

Figure 11. Graphs showing water-quality data for well USGS 41, 1990-2003, with

corresponding data for October-November 2003, Idaho National

Laboratory, Idaho ........................................................................... 30

Figure 12. Graphs showing water-quality data for well USGS 42, 1990-2003, with

corresponding data for October-November 2003, Idaho National

Laboratory, Idaho ........................................................................... 31

Figure 13. Graphs showing water-quality data for well USGS 43, 1990-2003, with

corresponding data for October-November 2003, Idaho National

Laboratory, Idaho ........................................................................... 32

Figure 14. Graphs showing water-quality data for well USGS 44, 1990-2003, with

corresponding data for October-November 2003, Idaho National

Laboratory, Idaho ........................................................................... 33

Figure 15. Graphs showing water-quality data for well USGS 45, 1990-2003, with

corresponding data for October-November 2003, Idaho National

Laboratory, Idaho ........................................................................... 34

Figure 16. Graphs showing water-quality data for well USGS 46, 1990-2003, with

corresponding data for October-November 2003, Idaho National

Laboratory, Idaho ........................................................................... 35

Figure 17. Graphs showing water-quality data for well USGS 47, 1990-2003, with

corresponding data for October-November 2003, Idaho National

Laboratory, Idaho ........................................................................... 36

Figure 18. Graphs showing water-quality data for well USGS 48, 1990-2003, with

corresponding data for October-November 2003, Idaho National

Laboratory, Idaho ........................................................................... 37

Figure 19. Graphs showing water-quality data for well USGS 50 (perched well),

1990-2003, with corresponding data for October-November 2003, Idaho

National Laboratory, Idaho ............................................................... 38

Figure 20. Graphs showing water-quality data for well USGS 51, 1990-2003, with

corresponding data for October-November 2003, Idaho National

Laboratory, Idaho ........................................................................... 39

Figure 21. Graphs showing water-quality data for well USGS 52, 1990-2003, with

corresponding data for October-November 2003, Idaho National

Laboratory, Idaho ........................................................................... 40

Figure 22. Graphs showing water-quality data for well USGS 57, 1990-2003, with

corresponding data for October-November 2003, Idaho National

Laboratory, Idaho ........................................................................... 41

Figure 23. Graphs showing water-quality data for well USGS 77, 1990-2003, with

corresponding data for October-November 2003, Idaho National

Laboratory, Idaho ........................................................................... 42

Figure 24. Graphs showing water-quality data for well USGS 82, 1990-2003, with

corresponding data for October-November 2003, Idaho National

Laboratory, Idaho ........................................................................... 44

Figures—Continued
Tables

Table 1. Radionuclide concentrations and gross radioactivity measurements, and

associated estimated standard deviations after purging 1 and 3 borehole

volumes of water from selected wells during 2004 and 2005, with

statistical comparisons of analytical results, Idaho National Laboratory,

Idaho .......................................................................................... 8

Table 2. Non-radioactive inorganic constituent concentrations and

F-pseudosigma estimated sample standard deviations after purging 1 and

3 borehole volumes of water from selected wells during 2004 and 2005,

with statistical comparisons of analytical results, Idaho National

Laboratory, Idaho ........................................................................... 10

Table 3. Total organic carbon and purgeable organic compound concentrations

and F-pseudosigma estimated sample standard deviations after purging 1

and 3 borehole volumes of water from selected wells during 2004 and

2005, with statistical comparisons of analytical results, Idaho National

Laboratory, Idaho ........................................................................... 14

Table 4. Tritium and strontium-90 concentrations, and associated estimated

standard deviations after purging 1, 2, and 3 borehole volumes of water

from selected wells during 1991, with statistical comparisons of analytical

results, Idaho National Laboratory, Idaho ................................................ 16

Figure 25. Graphs showing water-quality data for well USGS 85, 1990-2003, with

corresponding data for October-November 2003, Idaho National

Laboratory, Idaho ........................................................................... 45

Figure 26. Graphs showing water-quality data for well USGS 111, 1990-2003, with

corresponding data for October-November 2003, Idaho National

Laboratory, Idaho ........................................................................... 46

Figure 27. Graphs showing water-quality data for well USGS 112, 1990-2003, with

corresponding data for October-November 2003, Idaho National

Laboratory, Idaho ........................................................................... 47

Figure 28. Graphs showing water-quality data for well USGS 113, 1990-2003, with

corresponding data for October-November 2003, Idaho National

Laboratory, Idaho ........................................................................... 48

Figure 29. Graphs showing water-quality data for well USGS 114, 1990-2003, with

corresponding data for October-November 2003, Idaho National

Laboratory, Idaho ........................................................................... 49

Figure 30. Graphs showing water-quality data for well USGS 115, 1990-2003, with

corresponding data for October-November 2003, Idaho National

Laboratory, Idaho ........................................................................... 50

Figure 31. Graphs showing water-quality data for well USGS 116, 1990-2003, with

corresponding data for October-November 2003, Idaho National

Laboratory, Idaho ........................................................................... 51

Figure 32. Graphs showing water-quality data for well USGS 123, 1990-2003, with

corresponding data for October-November 2003, Idaho National

Laboratory, Idaho ........................................................................... 52

Figures—Continued
vi

Multiply By To obtain

foot (ft) 0.3048 meter

gallon (gal) 3.785 liter

liter per minute (L/min) 0.2642 gallon per minute

mile (mi) 1.609 kilometer

square mile (mi2) 2.590 square kilometer

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows:

 °F=(1.8×°C)+32

Specific conductance is given in microsiemens per centimeter at 25 degrees Celsius (μS/cm at 

25°C).

Concentrations of chemical constituents in water are given either in milligrams per liter (mg/L), 

micrograms per liter (μg/L), or picocuries per liter (piC/L).

Datums

Vertical coordinate information is referenced to the National Geodetic Vertical Datum of 1929 

(NGVD 29).

Horizontal coordinate information is referenced to the North American Datum of 1927 (NAD 27).

Altitude, as used in this report, refers to distance above the vertical datum.

Conversion Factors, Datums, Abbreviations and Acronyms

Conversion Factors

Abbreviations and Acronyms

Abbreviation or acronym Meaning

DEQ Idaho Department of Environmental Quality

DOE U.S. Department of Energy

ESRP Eastern Snake River Plain

ESRPA Eastern Snake River Plain aquifer

IBSP Inorganic Blind Sample Program

INL Idaho National Laboratory

INTEC Idaho Nuclear Technology and Engineering Center

LRL laboratory reporting level

LT-MDL long-term method detection limit

MPV most probable value

MRL minimum reporting level

NLCID no longer contained in decision

NWQL National Water Quality Laboratory

POC purgeable organic compond

RCRA Resource Conservation and Recovery Act

RESL Radiological and Environmental Sciences Laboratory

SRWS standard reference water samples

TOC total organic carbon 

USGS U.S. Geological Survey
Evaluation of Well-Purging Effects on Water-Quality 

Results for Samples Collected from the 

Eastern Snake River Plain Aquifer Underlying the 

Idaho National Laboratory, Idaho

By LeRoy L. Knobel

Abstract

This report presents qualitative and quantitative 

comparisons of water-quality data from the Idaho National 

Laboratory, Idaho, to determine if the change from purging 

three wellbore volumes to one wellbore volume has a 

discernible effect on the comparability of the data. Historical 

water-quality data for 30 wells were visually compared to 

water-quality data collected after purging only 1 wellbore 

volume from the same wells. Of the 322 qualitatively 

examined constituent plots, 97.5 percent met 1 or more of 

the criteria established for determining data comparability. A 

simple statistical equation to determine if water-quality data 

collected from 28 wells at the INL with long purge times (after 

pumping 1 and 3 wellbore volumes of water) were statistically 

the same at the 95-percent confidence level indicated that 

97.9 percent of 379 constituent pairs were equivalent. 

Comparability of water-quality data determined from 

both the qualitative (97.5 percent comparable) and quantitative 

(97.9 percent comparable) evaluations after purging 1 and 

3 wellbore volumes of water indicates that the change 

from purging 3 to 1 wellbore volumes had no discernible 

effect on comparability of water-quality data at the INL. 

However, the qualitative evaluation was limited because only 

October-November 2003 data were available for comparison 

to historical data. This report was prepared by the U.S. 

Geological Survey in cooperation with the U.S. Department of 

Energy.

Introduction

The Idaho National Laboratory (INL), which occupies 

about 890 mi2 of the eastern Snake River Plain (ESRP) in 

southeastern Idaho (fig. 1), is operated by the U.S. Department 

of Energy. INL facilities historically were used to develop 

peacetime atomic-energy applications, nuclear safety 

research, defense programs, and advanced energy concepts. 

Liquid-waste disposal resulted in detectable concentrations 

of several waste constituents in water from the eastern Snake 

River Plain aquifer (ESRPA) underlying the INL. The U.S. 

Geological Survey (USGS) INL Project Office provides 

an independent assessment of the migration and fate of 

waste constituents in water from the ESRPA. This report 

was prepared by the USGS in cooperation with the U.S. 

Department of Energy (DOE).

Ground-water-sampling protocols generally recommend 

that a well be purged prior to sampling (U.S. Environmental 

Protection Agency [USEPA], 1986). This recommendation is 

based on the assumption that the chemistry of stagnant water 

standing in a well casing or borehole is not the same as the 

chemistry of water in an aquifer. Three criteria commonly 

used to determine when a well has been purged sufficiently 

to yield representative water samples are: (1) removing an 

arbitrary number (usually three or more) wellbore volumes 

of water from the well; (2) monitoring field water-quality 

parameters—temperature, pH, specific conductance, turbidity, 

and dissolved oxygen—during purging until the values are 
id19-0013_fig01

Base from U.S. Geological Survey digital data, 1:24,000 and 1:100,000

Universal Transverse Mercator projection, Zone 12

Datum is North American Datum of 1927

0

0 10 20

10

30 KILOMETERS

20 MILES

Mud

Lake

Big

Lost

River

Little

Lost

River

Birch

Creek

Big

Southern

Butte

East

Middle Butte

Butte

BITTERROOT

RANGE

LEMHI RANGE

LOST RIVER RANGE

113°00’ 45’

44°

43°30’

45’

 113°15’ 112°30’

Howe

Arco

Terreton

Atomic City

Mud

Lake

103

4

83

107

Site 9 

Area 2

110

Site 14

TRA DISP

IET DISP

No Name 1

22 59

15

12

Site 19

Site 17

WS INEL-1

119

Arbor Test

IDAHO NATIONAL LABORATORY BOUNDARY

See figure 2

for additional

wells in this area

IDAHO

BOISE

EASTERN

SNAKE RIVER

PLAIN

IDAHO

NATIONAL

LABORATORY

Twin

Falls Pocatello

Idaho

Falls

EXPLANATION

107

Site 14

15

WELL COMPLETED IN THE SNAKE RIVER PLAIN AQUIFER AND SAMPLED FOR THIS

 STUDY AND BY BARTHOLOMAY (1993)—ENTRY, SITE 14, IS THE LOCAL WELL IDENTIFIER

WELL COMPLETED IN THE SNAKE RIVER PLAIN AQUIFER AND SAMPLED ONLY FOR THIS

 STUDY—ENTRY, 15, IS THE LOCAL WELL IDENTIFIER (NUMBERS ARE USGS WELLS,

 ABBREVIATED FOR MAP PRESENTATION)

WELL COMPLETED IN THE SNAKE RIVER PLAIN AQUIFER AND SAMPLED ONLY FOR

 THE STUDY BY BARTHOLOMAY (1993)—ENTRY, 107, IS THE LOCAL WELL IDENTIFIER

 (NUMBERS ARE USGS WELLS, ABBREVIATED FOR MAP PRESENTATION)

Figure 1. Location of eastern Snake River Plain, Idaho National Laboratory, and selected wells, Idaho. 

 Well-Purging Effects on Water-Quality Results, Eastern Snake River Plain Aquifer, Idaho National Laboratory, Idaho
stable; and (3) purging until hydraulic equilibrium takes place 

between well water and aquifer water (Gibs and Imbrigiotta, 

1990; American Society for Testing and Materials, 1999). 

USGS policy specifies removing at least 3 wellbore volumes 

of standing water while measuring field parameters until 

they are within specified stability criteria for five successive 

measurements (temperature, ±0.2oC; pH, ±0.1 standard units; 

specific conductance, ±3 percent if greater than 100 μS/cm 

or ±5 percent if less than 100 μS/cm; dissolved oxygen (DO) 

concentration, ±0.3 mg/L; and turbidity, ±10 percent for NTU 

less than 100). Exceptions to the 3-wellbore-volume rule 

are allowed if site characteristics or study objectives require 

modifying the standard procedure by changing the number of 

borehole volumes removed from the well (Wilde and others, 

1999). The American Society for Testing and Materials (1999, 

2001, 2002) provide detailed information on additional wellpurging criteria and combinations of the criteria described 

above, different types of equipment that can be used for 

purging and sampling ground water from monitoring wells, 

and alternative methods such as low-flow purging and 

sampling of ground water. Barcelona and others (2005) also 

described low-flow purging and sampling of ground water 

under high- and low-permeability conditions. 

In 2000, an areal polygon was established downgradient 

of the Idaho Nuclear Technology and Engineering Center 

(INTEC) with ground water that contained Resource 

Conservation and Recovery Act (RCRA) listed waste 

(fig. 2). In August 2000, the State of Idaho Department of 

Environmental Quality (DEQ) granted a conditional No 

Longer Contained In Decision (NLCID) to DOE, which 

allowed for ground water removed from specific wells in 

the polygon to be discharged to the ground surface (Brian 

Monson, State of Idaho Department of Environmental Quality, 

written commun., August 21, 2000). The conditional NLCID 

was renewed by the DEQ in June 2002 (Brian Monson, 

State of Idaho Department of Environmental Quality, written 

commun., June 19, 2002), but was withdrawn in June 2003 

(Brian Monson, State of Idaho Department of Environmental 

Quality, written commun., May 19, 2003). The USGS INL 

Project Office routinely collected ground-water samples from 

30 wells inside the polygon that required purging 3 wellbore 

volumes and generated about 25,000 gal of purge water per 

sampling event. Beginning October 2003, the USGS was no 

longer allowed to discharge purge water to the ground surface. 

DEQ required that purge water be treated as a RCRA-listed 

waste, which necessitated pumping it into containers and 

transporting it to an approved disposal site.

In October 2003, the USGS began containerization 

of purge water removed from wells inside the polygon. 

Removing 3 wellbore volumes of purge water from many 

of these wells was not possible due to the large volumes of 

purge water and the size limitations of the containers. The 

USGS INL Project Office initiated a revised procedure to 

collect samples after purging 1 wellbore volume if field 

water-quality parameters stabilized. To evaluate the effects 

of decreased purging on the comparability of data, two 

techniques were used (1) a qualitative comparison of historical 

water-quality data from wells inside the polygon with waterquality data subsequently collected from the same wells after 

only 1 wellbore volume was purged, and (2) a quantitative 

comparison of data collected at selected wells (figs. 1, 2) after 

purging 1 wellbore volume with data collected at the same 

wells after purging 3 wellbore volumes.

Purpose and Scope

The purpose of this report is to present results of the 

qualitative and quantitative comparisons of water-quality 

data to determine if a change from purging 3 wellbore 

volumes to 1 wellbore volume has a discernible effect on data 

comparability. Specific objectives of the study were to: (1) 

plot and visually compare historical water-quality data for 30 

wells in the RCRA-listed waste polygon with data collected 

after the change to purging only 1 wellbore volume; (2) use 

a simple statistical equation to determine if water-quality 

data collected from 17 long-pumping wells (after pumping 

1 and 3 wellbore volumes) were statistically the same at the 

95-percent confidence level; and (3) use the same simple 

statistical equation to re-evaluate if water-quality data reported 

by Bartholomay (1993) from 11 long-pumping wells at the 

INL (after 1, 2, and 3 wellbore volumes were pumped) were 

statistically the same at the 95-percent confidence level.

Geohydrologic Setting

The ESRP is a northeast-trending structural basin about 

200-mi long and 50- to 70-mi wide. The basin is bounded 

by faults on the northwest and downwarping and faulting 

on the southeast. The basin is filled with basaltic lava flows 

interbedded with terrestrial sediments (Whitehead, 1986). 

Individual basalt flows range from 10- to 50-ft thick, although 

the average thickness probably ranges from 20 to 25 ft 

(Mundorff and others, 1964, p. 143). Sedimentary deposits 

consist mainly of lenticular beds of sand, silt, and clay with 

Introduction 
id19-0013_fig02

WELL COMPLETED IN THE EASTERN SNAKE RIVER PLAIN AQUIFER OR PERCHED-WATER 

 ZONE AND SAMPLED ONLY FOR THIS STUDY—ENTRY, USGS 85, IS THE LOCAL WELL 

 IDENTIFIER

WELL COMPLETED IN THE SNAKE RIVER PLAIN AQUIFER AND SAMPLED FOR THIS STUDY

 AND BY BARTHOLOMAY (1993)—ENTRY, USGS 82, IS THE LOCAL WELL IDENTIFIER

BOUNDARY OF RESOURCE CONSERVATION AND RECOVERY ACT LISTED WASTE POLYGON

CENTRAL FACILITIES AREA

INTEC IDAHO NUCLEAR TECHNOLOGY AND ENGINEERING CENTER

CFA

USGS 20

USGS 85

USGS 82

USGS 52

USGS 50

USGS 111 USGS 116

USGS 57

USGS 123 USGS 51

USGS 48

USGS 47

USGS 42

USGS 41 USGS 40

USGS 43

USGS 44

USGS 45

USGS 46

USGS 112

USGS 113

USGS 114 USGS 115

USGS 77

USGS 34

USGS 35

USGS 36

USGS 37

USGS 38

USGS 39

CFA LF 2-10

USGS 20

USGS 85

USGS 82

USGS 52

USGS 50

USGS 111 USGS 116

USGS 57

USGS 123 USGS 51

USGS 48

USGS 47

USGS 42

USGS 41 USGS 40

USGS 43

USGS 44

USGS 45

USGS 46

USGS 112

USGS 113

USGS 114 USGS 115

USGS 77

USGS 34

USGS 35

USGS 36

USGS 37

USGS 38

USGS 39

CFA LF 2-10

Base from U.S. Geological Survey digital data, 1:24,000 and 1:100,000

Universal Transverse Mercator projection, Zone 12

Datum is North American Datum of 1927 EXPLANATION

USGS 85

USGS 82

112°58’ 112°55’

43°34’

33’

43°32’

57’ 56’

Big Lost River

INTEC

CFA Lincoln Blvd.

Figure 2. Locations of selected wells near the Idaho Nuclear Technology and Engineering Center and Central 

Facilities Area, Idaho.

 Well-Purging Effects on Water-Quality Results, Eastern Snake River Plain Aquifer, Idaho National Laboratory, Idaho
lesser amounts of gravel. Locally, rhyolitic lava flows and 

tuffs are exposed at the land surface and may exist at depth 

under most of the ESRP. A 10,365-ft-deep test hole at the 

INL penetrated 2,160 ft of basalt and sediment and 8,205 ft of 

rhyolitic volcanic rocks (Mann, 1986). 

Basaltic lava flows and interbedded sedimentary deposits 

combine to form the ESRPA, the main source of ground 

water on the ESRP. Depth to water in the ESRPA at the INL 

ranges from about 200 ft in the northern part to more than 

900 ft in the southern part. Direction of regional ground-water 

flow in the ESRPA generally is from the northeast to the 

southwest. Water moves horizontally through basalt interflow 

zones and vertically through joints and interfingering edges 

of the interflow zones. Infiltration of surface water, heavy 

pumpage, geologic conditions, and seasonal fluxes of recharge 

and discharge locally affect the movement of ground water 

(Garabedian, 1986).

Previous Investigations

Many previous studies evaluated well-purging criteria to 

determine when chemistry of water withdrawn from wells was 

representative of the chemistry of water in the aquifer. Most 

studies evaluated how changing well-purging criteria affected 

organic compound concentrations, especially in shallow sand 

and gravel aquifers. Dumouchelle and others (1990), Gibs 

and others (1990), and Herzog and others (1991) provide 

a comprehensive list of reports presenting results of these 

studies. Robin and Gilham (1987) used conservative inorganic 

tracers (sodium bromide and sodium chloride) to evaluate 

the number of purge volumes required to achieve chemical 

equilibrium between well water and aquifer water and 

concluded that less than three wellbore volumes was sufficient 

under the conditions of their tests. Robin and Gilham (1987) 

also pointed out that the findings of studies evaluating wellpurging criteria are site specific and depend on local hydraulic, 

hydrologic, and geochemical conditions. 

Barcelona and others (2005) presented results of a case 

study to illustrate low-flow sampling performance under 

minimal (low permeability) and significant, but stable (high 

permeability) drawdown conditions. They concluded (for 

the conditions of their study) that constituent concentrations 

stabilized after 2 wellbore volumes for a low-permeability well 

and after one-half wellbore volumes for a high-permeability 

well. They also concluded that stabilization of field waterquality parameters more effectively indicated when to collect 

samples than the number of wellbore volumes purged from a 

well. 

The effect on concentrations of inorganic, organic, and 

radioactive constituents in water from deep aquifers like the 

ESRPA that result from changing well-purging criteria has 

not been studied extensively. However, Bartholomay (1993) 

evaluated changes in concentrations of tritium and strontium90 after purging 1, 2, and 3 borehole volumes. Samples were 

collected from 11 ESRPA wells and analyzed by DOE’s 

Radiological and Environmental Sciences Laboratory (RESL) 

for tritium and strontium-90. Bartholomay (1993) presents 

statistical comparisons of analytical data from samples 

collected at each well. A pair of equations derived from a test 

method recommended by the American Society for Testing 

and Materials (1988) was used for the comparisons. Wells 

included in his study were selected because they required 1 or 

more hours to purge 1 borehole volume of water. Bartholomay 

(1993) concluded that tritium and strontium-90 concentrations 

in water samples from wells with purge times greater than 3 

hrs at the INL are not measurably affected by purging either 1, 

2, or 3 borehole volumes.

Study Methods

Sample Collection Methods

Methods of collecting water samples for this study 

generally followed guidelines established by the USGS 

and documented in the USGS National Field Manual (U.S. 

Geological Survey, variously dated), in the USGS Idaho Water 

Science Center Quality-Assurance Plan for water-quality 

activities (U.S. Geological Survey, Idaho Water Science 

Center, written commun., 2005), and in Bartholomay and 

others (2003). Containerization of purge water necessitated 

some minor adjustments to the guidelines in Bartholomay 

and others (2003). It was necessary to split the well discharge 

into three streams to accommodate sample collection, 

continuous measurement of the field-water-quality indicators 

(temperature, pH, specific conductance, and DO), and 

collection of excess purge water. Excess purge water was 

collected at the discharge point and routed through canvas 

hoses to trailer-mounted containers. Containerized purge water 

was then transported to an approved disposal site near INTEC.

Study Methods 
Analytical Methods

DOE’s Radiological and Environmental Sciences 

Laboratory (RESL) analyzed water samples for selected 

radiochemical constituents. A discussion of the procedures 

used by RESL for the analysis of radionuclides in water 

samples is provided in reports by Bodner and Percival [eds.] 

(1982) and U.S. Department of Energy (1995). Analytical 

methods used by the USGS National Water Quality 

Laboratory (NWQL) for selected organic and inorganic 

constituents are described by Goerlitz and Brown (1972), 

Skougstad and others (1979), Wershaw and others (1987), 

Fishman and Friedman (1989), Faires (1992), Fishman (1993), 

and Rose and Schroeder (1995). A list of some analytical 

methods currently used at the NWQL is available at http://

wwwnwql.cr.usgs.gov/Public/ref_list.html. Other analytical 

methods from the USEPA currently used at the NWQL are 

available at http://www.epa.gov/epahome/publications.html. 

Analytical methods from the ASTM that are currently used at 

the NWQL are available at http://www.astm.org.

Guidelines for Interpretation of Analytical 

Results

Concentrations of radionuclides are reported with 

an estimated sample standard deviation, s, obtained by 

propagating sources of analytical uncertainty in measurements. 

Guidelines for interpreting analytical results for radionuclides 

are based on an extension of a method by Currie (1984) and 

are given in a report by Knobel and others (1999). In this 

report, radionuclide concentrations less than 3s are considered 

to be below a reporting level.

Water samples were analyzed for the following selected 

non-radioactive chemical constituents: dissolved trace 

elements, common ions, nutrients, and purgeable organic 

compounds. Minimum reporting levels (MRL’s), long-term 

method detection limits (LT-MDL’s), and laboratory reporting 

levels (LRL’s), are used by the NWQL to determine when 

a chemical constituent has been detected with sufficient 

confidence (Childress and others, 1999).

The MRL is the smallest measured constituent 

concentration that can be reliably reported using a given 

analytical method (Timme, 1995). In this report, MRL’s 

are used only to report concentrations of purgeable organic 

compounds. The LT-MDL controls false positive error and is 

determined by calculating the standard deviation of a large 

sample population (at least 24 measurements) of spikedsample measurements over an extended period (often 1 year). 

At the NWQL, the LT-MDL can change on a yearly basis. 

The chance of falsely reporting a concentration at or greater 

than the LT-MDL for a sample that did not contain the analyte 

is predicted to be less than or equal to 1 percent (Childress 

and others, 1999, p. 19). A falsely reported detection is 

known as a false positive and is an error of the first type in 

hypothesis testing. The LRL controls false negative error and 

is determined so the probability of falsely reporting a nondetection for a sample containing an analyte at a concentration 

equal to or greater than the LRL is predicted to be less than or 

equal to 1 percent (Childress and others, 1999, p. 19). Falsely 

reporting a non-detection is known as a false negative and is 

an error of the second type in hypothesis testing. The LRL 

generally is equal to twice the yearly-determined LT-MDL.

Analytes detected at concentrations between the LT-MDL 

and the LRL that pass identification criteria are estimated. 

Estimated concentrations are noted with a remark code “E.” 

These data should be used with the understanding that their 

uncertainty is greater than data reported without the “E” 

remark code. For consistency with previous publications, 

estimated concentrations less than the LRLs are treated as 

censored data in this report. For censored data used in this 

report, values are less than the LRL or MRL. 

Statistical Equivalency of Sample Pairs

Statistical equivalency of chemical-constituent 

concentrations in sample pairs was determined following the 

method outlined by Williams (1996). In this method, statistical 

equivalence is determined within a specified confidence level. 

A value for the standard deviate, Z, is calculated, and then the 

level of significance of the result is evaluated (evaluation of 

the level of significance assumes that the sample population 

is distributed normally). For this report, concentrations of 

individual constituents in sample pairs (constituent pairs) 

were considered equivalent when the results were within two 

standard deviations of each other. At this confidence level 

(95-percent), the level of significance, determined from a 

standard normal probability curve, was 0.05 for a two-tailed 

test and corresponded to a Z-value of 1.96.

The equation used to determine Z was adapted from Volk 

(1969):

Z x y

s s x y

= −

+

| |

( ) ( ) 2 2 , (1)

 Well-Purging Effects on Water-Quality Results, Eastern Snake River Plain Aquifer, Idaho National Laboratory, Idaho
where

x is the concentration of a constituent in the 

routine sample,

y is the concentration of the same constituent in 

the sequential replicate sample,

sx is the standard deviation of x, and

sy is the standard deviation of y.

When the population is not distributed normally or an 

approximation of the standard deviation is used, a Z-value 

less than 1.96 must be considered a guide when testing for 

equivalence. Constituent concentrations in sample pairs were 

considered statistically equivalent when the calculated Z-value 

was less than or equal to 1.96. Constituent concentrations also 

were considered statistically equivalent, although Z-values 

were not calculated, when the concentration in both samples 

was reported as less than the LRL or MRL. In this case, the 

Z-value was reported as zero.

In this report, three types of sample pairs were evaluated 

for statistical equivalency: (1) a replicate-sample pair collected 

from well USGS 22 (fig. 1); (2) sample pairs collected after 

purging 1 and 3 wellbore water volumes at each of 17 wells 

(figs. 1, 2); and (3) sample pairs collected in an earlier study 

(Bartholomay, 1993) after purging 1, 2, and 3 wellbore 

volumes at each of 11 wells (figs. 1, 2). Each sample pair 

generates multiple constituent pairs.

Gross Radioactivity and Radionuclides

Using equation 1 is straightforward in determining 

whether results of radiochemical analyses of a pair of samples 

were equivalent. RESL reports radionuclide concentrations 

with an estimated sample standard deviation obtained by 

propagating sources of analytical uncertainty in measurements. 

Estimated sample standard deviations can be used directly 

in equation 1 to calculate a Z-value. Concentrations of 

radionuclides and measurements of gross radioactivity, 

estimated sample standard deviations, and calculated Z-values 

are provided in table 1.

Non-radioactive Inorganic Constituents

Equation 1 cannot be applied directly to results when 

no standard deviations or uncertainties are reported by the 

laboratory. The NWQL does not report standard deviations 

with analytical results for non-radioactive inorganic 

constituents. As a result, approximations of standard 

deviations were used. The USGS Branch of Quality Assurance 

conducts an Inorganic Blind Sample Program (IBSP) in which 

reference samples disguised as environmental samples are 

submitted to the NWQL. Maloney and others (1993) describe 

the program and present evaluations of the analytical results. 

Samples sent by the IBSP to the NWQL are prepared from 

standard reference water samples (SRWS’s). SRWS’s are 

used by the USGS SRWS project in a round-robin laboratory 

evaluation program described by Farrar and Long (1997). 

Until 1988, the SRWS project used means and standard 

deviations to describe the round-robin data sets. Since 1988, 

the project used median and F-pseudosigma as a summary of 

location and variability in data sets. Hoaglin and others (1983) 

showed that F-pseudosigma yields an unbiased estimate of 

standard deviation when the data distribution is Gaussian 

(http://bqs.usgs.gov/bsp/regress.htm). 

Mean and median values in the SRWS data sets 

traditionally were referred to as Most Probable Values 

(MPV’s). The IBSP uses SRWS data sets to estimate the 

MPV’s of the IBSP sample mixes. MPV estimates are based 

on the proportion of the SRWS’s used in making up the sample 

mixes. Because SRWS data sets are not always Gaussian, 

the regression equations were derived from a combination of 

parametric and nonparametric results. Regression equations 

were derived for each constituent by regressing the appropriate 

F-psuedosigma or standard deviation against the IBSP 

MPV using ordinary least squares. Helsel and Hirsch (1992) 

provided a general model for estimation of ordinary leastsquares:

Fσi = βo + β1MPVi + εi i = 1, 2, ..., n (2)

where

Fσi is the ith observation of the response variable, Fσ,

MPVi is the ith observation of the explanatory variable, 

MPV,

βo is the intercept,

β1 is the slope,

εi is the random error or residual for the ith 

observation, and

n is the sample size.

SRWS project summary data for semi-annual roundrobin sample studies during 2004-05 were used by the IBSP to 

derive regression equations for each constituent. Concentration 

ranges of the SRWS project summary data sets used, the 

derived Fσ equations, and the correlations are available at 

http://bqs.usgs.gov/bsp/regress.htm. F-pseudosigma values 

were calculated for each analytical result using the regression 

equations provided by the IBSP. F-pseudosigma values, which 

correspond to the appropriate time period and concentration 

range, were then used as an estimate of standard deviations 

in equation 1 to calculate Z-values. Concentrations of nonradioactive inorganic constituents, F-pseudosigma estimated 

sample standard deviations, and calculated Z-values are 

provided in table 2.

Study Methods 
Table 1. Radionuclide concentrations and gross radioactivity measurements, and associated estimated standard deviations after 

purging 1 and 3 borehole volumes of water from selected wells during 2004 and 2005, with statistical comparisons of analytical results, 

Idaho National Laboratory, Idaho.

[See figures 1 and 2 for location of wells. Analytical results and estimated standard deviations are in picocuries per liter. Shading indicates not statistically 

comparable at the 95-percent confidence level. Z-value, calculated using equation 1 (a Z-value less than or equal to 1.96 indicates statistical equivalence at 

the 95-percent confidence level). Abbreviations: BHV, borehole volume; CFA, Central Facilities Area; NA, not applicable; NS, not sampled; Repl., replicate 

sample; SD, estimated standard deviation reported as 1 sigma; USGS, U.S. Geological Survey]

Well identifier Sample 

date

Radionuclide concentrations

Tritium Strontium-90

1-BHV SD 3-BHV SD Z-value 1-BHV SD 3-BHV SD Z-value

Area 2 10-05-04 -110 120 0 130 0.62 0.2 0.6 1.0 0.6 0.94

IET DISP 10-09-04 -80 120 -40 130 .23 -.2 .7 .4 .7 .61

Site 14 10-12-04 -130 120 -120 120 .06 NS NS NS NS NA

Site 19 10-04-04 -110 120 -100 120 .06 NS NS NS NS NA

TRA DISP 10-07-04 4,200 300 3,900 300 .71 -.4 .7 4.1 .9 3.95

USGS 4 10-14-04 -80 120 -60 120 .12 NS NS NS NS NA

USGS 15 10-12-04 -70 120 -30 130 .23 1.2 .6 1.4 .6 .24

WS INEL 1 10-27-04 -60 120 -80 120 .12 NS NS NS NS NA

Arbor Test 04-25-05 -90 50 -10 60 1.02 NS NS NS NS NA

CFA LF 2-10 04-12-05 3,060 160 2,880 160 .80 .5 .7 .1 .8 .38

No Name 1 04-11-05 -80 50 -70 50 .14 .1 .7 1.9 .7 1.82

Site 9 04-28-05 0 60 -40 50 .51 -1.2 .6 -1.1 .6 .12

Site 17 04-27-05 -20 50 -40 50 .28 -.8 .6 -4.2 1.5 2.10

USGS 12 04-21-05 30 60 -70 50 1.28 NS NS NS NS NA

USGS 22 04-25-05 50 60 30 60 .24 NS NS NS NS NA

USGS 22, 3-BHV, Repl. 04-25-05 NS NS 0 60 .35 NS NS NS NS NA

USGS 103 04-18-05 -70 50 20 60 1.15 NS NS NS NS NA

USGS 119 03-31-05 -80 50 -50 50 .42 .6 .7 .5 .7 .10

Well identifier Sample 

date

Radionuclide concentrations

Cesium-137 Americium-241

1-BHV SD 3-BHV SD Z-value 1-BHV SD 3-BHV SD Z-value

Area 2 10-05-04 NS NS NS NS NA NS NS NS NS NA

IET DISP 10-09-04 NS NS NS NS NA NS NS NS NS NA

Site 14 10-12-04 -20 20 11.9 22.1 1.07 NS NS NS NS NA

Site 19 10-04-04 NS NS NS NS NA NS NS NS NS NA

TRA DISP 10-07-04 -14.5 37 -30 40 .28 NS NS NS NS NA

USGS 4 10-14-04 -12.1 33.2 0 20 .31 NS NS NS NS NA

USGS 15 10-12-04 NS NS NS NS NA NS NS NS NS NA

WS INEL 1 10-27-04 NS NS NS NS NA NS NS NS NS NA

Arbor Test 04-25-05 NS NS NS NS NA NS NS NS NS NA

CFA LF 2-10 04-12-05 0 30 40 30 .94 NS NS NS NS NA

No Name 1 04-11-05 40 30 50 40 .20 NS NS NS NS NA

Site 9 04-28-05 NS NS NS NS NA NS NS NS NS NA

Site 17 04-27-05 NS NS NS NS NA NS NS NS NS NA

USGS 12 04-21-05 -20 20 20 20 1.41 NS NS NS NS NA

USGS 22 04-25-05 NS NS NS NS NA NS NS NS NS NA

USGS 103 04-18-05 -15.4 22 -20 40 .10 NS NS NS NS NA

USGS 119 03-31-05 0 40 40 20 .89 0.006 0.009 0.003 0.008 0.25

 Well-Purging Effects on Water-Quality Results, Eastern Snake River Plain Aquifer, Idaho National Laboratory, Idaho
Table 1. Radionuclide concentrations and gross radioactivity measurements, and associated estimated standard deviations after 

purging 1 and 3 borehole volumes of water from selected wells during 2004 and 2005, with statistical comparisons of analytical results, 

Idaho National Laboratory, Idaho.—Continued

[See figures 1 and 2 for location of wells. Analytical results and estimated standard deviations are in picocuries per liter. Shading indicates not statistically 

comparable at the 95-percent confidence level. Z-value, calculated using equation 1 (a Z-value less than or equal to 1.96 indicates statistical equivalence at 

the 95-percent confidence level). Abbreviations: BHV, borehole volume; CFA, Central Facilities Area; NA, not applicable; NS, not sampled; Repl., replicate 

sample; SD, estimated standard deviation reported as 1 sigma; USGS, U.S. Geological Survey]

Well identifier Sample 

date

Radionuclide concentrations

Plutonium-238 Plutonium-239, -240

1-BHV SD 3-BHV SD Z-value 1-BHV SD 3-BHV SD Z-value

Area 2 10-05-04 NS NS NS NS NA NS NS NS NS NA

IET DISP 10-09-04 NS NS NS NS NA NS NS NS NS NA

Site 14 10-12-04 NS NS NS NS NA NS NS NS NS NA

Site 19 10-04-04 NS NS NS NS NA NS NS NS NS NA

TRA DISP 10-07-04 NS NS NS NS NA NS NS NS NS NA

USGS 4 10-14-04 NS NS NS NS NA NS NS NS NS NA

USGS 15 10-12-04 NS NS NS NS NA NS NS NS NS NA

WS INEL 1 10-27-04 NS NS NS NS NA NS NS NS NS NA

Arbor Test 04-25-05 NS NS NS NS NA NS NS NS NS NA

CFA LF 2-10 04-12-05 NS NS NS NS NA NS NS NS NS NA

No Name 1 04-11-05 NS NS NS NS NA NS NS NS NS NA

Site 9 04-28-05 NS NS NS NS NA NS NS NS NS NA

Site 17 04-27-05 NS NS NS NS NA NS NS NS NS NA

USGS 12 04-21-05 NS NS NS NS NA NS NS NS NS NA

USGS 22 04-25-05 NS NS NS NS NA NS NS NS NS NA

USGS 103 04-18-05 NS NS NS NS NA NS NS NS NS NA

USGS 119 03-31-05 0.003 0.005 0.003 0.006 0 0.006 0.006 0.003 0.006 0.35

Well identifier Sample 

date

Gross radioactivity measurements

Alpha Beta

1-BHV SD 3-BHV SD Z-value 1-BHV SD 3-BHV SD Z-value

Area 2 10-05-04 NS NS NS NS NA NS NS NS NS NA

IET DISP 10-09-04 NS NS NS NS NA NS NS NS NS NA

Site 14 10-12-04 0.3 0.6 1.0 0.8 0.70 1.09 2.15 4 2 0.99

Site 19 10-04-04 NS NS NS NS NA NS NS NS NS NA

TRA DISP 10-07-04 NS NS NS NS NA NS NS NS NS NA

USGS 4 10-14-04 .7 .7 .7 .7 0 5 2 5 2 0

USGS 15 10-12-04 NS NS NS NS NA NS NS NS NS NA

WS INEL 1 10-27-04 NS NS NS NS NA NS NS NS NS NA

Arbor Test 04-25-05 NS NS NS NS NA NS NS NS NS NA

CFA LF 2-10 04-12-05 .0 .6 .0 .6 0 3 2 3 2 0

No Name 1 04-11-05 .0 .6 .0 .6 0 1 2 5 2 1.41

Site 9 04-28-05 NS NS NS NS NA NS NS NS NS NA

Site 17 04-27-05 NS NS NS NS NA NS NS NS NS NA

USGS 12 04-21-05 .3 .6 .3 .6 0 -1 2 1 2 .71

USGS 22 04-25-05 NS NS NS NS NA NS NS NS NS NA

USGS 103 04-18-05 .3 .6 .3 .6 0 1.44 2.26 3 2 .52

USGS 119 03-31-05 NS NS NS NS NA NS NS NS NS NA

Study Methods   
Well identifier Sample 

date

Inorganic constituent concentrations

Sodium (mg/L) Chloride (mg/L)

1-BHV F-pseudos 3-BHV F-pseudos Z-value 1-BHV F-pseudos 3-BHV F-pseudos Z-value

Area 2 10-05-04 16.51 0.698 16.60 0.702 0.09 16.83 0.882 16.77 0.881 0.05

IET DISP 10-09-04 16.91 .715 16.25 .687 .67 20.23 .975 19.20 .947 .76

Site 14 10-12-04 14.83 .627 14.80 .626 .03 8.73 .662 8.74 .662 .01

Site 19 10-04-04 8.91 .377 8.88 .376 .06 10.22 .703 10.12 .700 .10

TRA DISP 10-07-04 11.19 .473 10.97 .464 .33 10.55 .711 10.51 .710 .04

USGS 4 10-14-04 47.24 1.998 47.35 2.003 .04 29.91 1.238 29.88 1.237 .02

USGS 15 10-12-04 15.01 .635 15.10 .639 .10 18.82 .936 18.94 .940 .09

WS INEL 1 10-27-04 17.27 .731 17.39 .736 .12 61.29 2.092 60.90 2.081 .13

Arbor Test 04-25-05 NS NS NS NS NA 14.46 .818 14.49 .819 .03

CFA LF 2-10 04-12-05 12.69 .537 12.98 .549 .38 33.93 1.347 32.13 1.298 .96

No Name 1 04-11-05 11.05 .467 10.49 .444 .87 20.12 .972 19.49 .955 .46

Site 9 04-28-05 12.50 .529 12.33 .522 .23 14.20 .811 14.22 .811 .02

Site 17 04-27-05 10.33 .437 10.38 .439 .08 9.85 .692 9.82 .692 .03

USGS 12 04-21-05 14.15 .599 14.73 .623 .67 25.62 1.121 26.81 1.154 .74

USGS 22 04-25-05 21.62 .915 22.86 .967 .93 62.07 2.113 63.63 2.155 .52

USGS 22, 3-BHV, Repl. 04-25-05 NS NS 23.87 1.010 .72 NS NS 64.05 2.167 .14

USGS 103 04-18-05 15.48 .655 15.03 .636 .49 17.10 .890 17.13 .890 .02

USGS 119 03-31-05 10.78 .456 10.63 .450 .23 10.02 .697 9.69 .688 .34

Table 2. Non-radioactive inorganic constituent concentrations and F-pseudosigma estimated sample standard deviations after purging 

1 and 3 borehole volumes of water from selected wells during 2004 and 2005, with statistical comparisons of analytical results, Idaho 

National Laboratory, Idaho.

[See figures 1 and 2 for location of wells. Analytical results and F-pseudosigma estimated standard deviations are in milligrams per liter (mg/L) or micrograms 

per liter (mg/L). Shading indicates not statistically comparable at the 95-percent confidence level. Abbreviations: BHV, borehole volume; F-pseudos, 

F-pseudosigma estimated sample standard deviation; NA, not applicable; NC, not calculated; NS, not sampled; Repl., replicate sample; USGS, U.S. Geological 

Survey; Z-value, calculated using equation 1 (a Z-value less than or equal to 1.96 suggests statistical equivalence at the 95-percent confidence level); E, 

estimated; <, less than]

Well identifier Sample 

date

Inorganic constituent concentrations

Ammonia (mg/L) Phosphate (mg/L)

1-BHV F-pseudos 3-BHV F-pseudos Z-value 1-BHV F-pseudos 3-BHV F-pseudos Z-value

Area 2 10-05-04 <0.04 NA <0.04 NA 0 <0.018 NA <0.018 NA 0

IET DISP 10-09-04 .529 0.037 .501 0.036 .54 .164 0.008 .157 0.007 .66

Site 14 10-12-04 <.04 NA <.04 NA 0 .010E NA <.018 NA 0

Site 19 10-04-04 <.04 NA <.04 NA 0 .031 NC .027 NC NA

TRA DISP 10-07-04 <.04 NA <.04 NA 0 .031 NC .027 NC NA

USGS 4 10-14-04 <.04 NA <.04 NA 0 .015E NA .015E NA 0

USGS 15 10-12-04 <.04 NA <.04 NA 0 .013E NA .015E NA 0

WS INEL 1 10-27-04 NS NS NS NS NA NS NS NS NS NA

Arbor Test 04-25-05 NS NS NS NS NA NS NS NS NS NA

CFA LF 2-10 04-12-05 <.04 NA <.04 NA 0 .013E NA .014E NA 0

No Name 1 04-11-05 <.04 NA <.04 NA 0 .013E NA .012E NA 0

Site 9 04-28-05 <.04 NA <.04 NA 0 <.018 NA <.018 NA 0

Site 17 04-27-05 <.04 NA <.04 NA 0 .011E NA .010E NA 0

USGS 12 04-21-05 <.04 NA <.04 NA 0 .017E NA .017E NA 0

USGS 22 04-25-05 NS NS NS NS NA NS NS NS NS NA

USGS 103 04-18-05 <.04 NA <.04 NA 0 <.018 NA <.018 NA 0

USGS 119 03-31-05 <.04 NA <.04 NA 0 <.018 NA <.018 NA 0

10 Well-Purging Effects on Water-Quality Results, Eastern Snake River Plain Aquifer, Idaho National Laboratory, Idaho
Table 2. Non-radioactive inorganic constituent concentrations and F-pseudosigma estimated sample standard deviations after purging 

1 and 3 borehole volumes of water from selected wells during 2004 and 2005, with statistical comparisons of analytical results, Idaho 

National Laboratory, Idaho.—Continued

[See figures 1 and 2 for location of wells. Analytical results and F-pseudosigma estimated standard deviations are in milligrams per liter (mg/L) or micrograms 

per liter (mg/L). Shading indicates not statistically comparable at the 95-percent confidence level. Abbreviations: BHV, borehole volume; F-pseudos, 

F-pseudosigma estimated sample standard deviation; NA, not applicable; NC, not calculated; NS, not sampled; Repl., replicate sample; USGS, U.S. Geological 

Survey; Z-value, calculated using equation 1 (a Z-value less than or equal to 1.96 suggests statistical equivalence at the 95-percent confidence level); E, 

estimated; <, less than]

Well identifier Sample 

date

Inorganic constituent concentrations

Nitrate (mg/L) Sulfate (mg/L)

1-BHV F-pseudos 3-BHV F-pseudos Z-value 1-BHV F-pseudos 3-BHV F-pseudos Z-value

Area 2 10-05-04 1.301 0.072 1.293 0.072 0.08 15.48 0.917 15.36 0.913 0.09

IET DISP 10-09-04 .227 .013 .369 .020 5.95 31.77 1.505 31.77 1.505 0

Site 14 10-12-04 .587 .033 .588 .033 .02 NS NS NS NS NA

Site 19 10-04-04 1.050 .058 1.043 .058 .09 21.03 1.117 21.04 1.118 .01

TRA DISP 10-07-04 1.050 .058 1.043 .058 .09 33.02 1.550 32.76 1.541 .12

USGS 4 10-14-04 4.498 NC 4.540 NC NA NS NS NS NS NA

USGS 15 10-12-04 1.266 .070 1.289 .071 .23 25.46 1.277 25.56 1.281 .06

WS INEL 1 10-27-04 NS NS NS NS NA 39.06 1.768 38.94 1.764 .05

Arbor Test 04-25-05 NS NS NS NS NA NS NS NS NS NA

CFA LF 2-10 04-12-05 1.505 .083 1.480 .082 .21 NS NS NS NS NA

No Name 1 04-11-05 .611 .034 .629 .035 .37 NS NS NS NS NA

Site 9 04-28-05 .665 .037 .681 .038 .30 24.18 1.231 24.65 1.248 .27

Site 17 04-27-05 .965 .053 .969 .054 .05 19.70 1.069 19.58 1.065 .08

USGS 12 04-21-05 1.659 .092 1.746 .097 .65 29.22 1.413 29.97 1.440 .37

USGS 22 04-25-05 NS NS NS NS NA NS NS NS NS NA

USGS 103 04-18-05 .867 .048 .875 .048 .12 NS NS NS NS NA

USGS 119 03-31-05 1.430 .079 1.490 .083 .52 40.15 1.807 37.22 1.702 1.18

Well identifier Sample

date

Inorganic constituent concentrations

Chromium (mg/L) Antimony (mg/L)

1-BHV F-pseudos 3-BHV F-pseudos Z-value 1-BHV F-pseudos 3-BHV F-pseudos Z-value

Area 2 10-05-04 NS NS NS NS NA NS NS NS NS NA

IET DISP 10-09-04 NS NS NS NS NA NS NS NS NS NA

Site 14 10-12-04 6.18 NC 6.50 NC NA NS NS NS NS NA

Site 19 10-04-04 5.74 NC 5.51 NC NA NS NS NS NS NA

TRA DISP 10-07-04 13.09 1.121 12.06 1.072 0.66 NS NS NS NS NA

USGS 4 10-14-04 10.16 .981 10.40 .992 .17 NS NS NS NS NA

USGS 15 10-12-04 NS NS NS NS NA NS NS NS NS NA

WS INEL 1 10-27-04 8.96 .923 10.00 .973 .78 NS NS NS NS NA

Arbor Test 04-25-05 3.25 NC 3.55 NC NA NS NS NS NS NA

CFA LF 2-10 04-12-05 11.68 1.054 12.12 1.075 .29 NS NS NS NS NA

No Name 1 04-11-05 7.72 .864 8.32 .892 .48 0.169E NA 0.178E NA 0

Site 9 04-28-05 NS NS NS NS NA NS NS NS NS NA

Site 17 04-27-05 NS NS NS NS NA NS NS NS NS NA

USGS 12 04-21-05 10.57 1.000 10.19 .982 .27 NS NS NS NS NA

USGS 22 04-25-05 NS NS NS NS NA NS NS NS NS NA

USGS 103 04-18-05 8.21 .887 8.36 .894 .12 NS NS NS NS NA

USGS 119 03-31-05 NS NS NS NS NA NS NS NS NS NA

Study Methods 11
Table 2. Non-radioactive inorganic constituent concentrations and F-pseudosigma estimated sample standard deviations after purging 

1 and 3 borehole volumes of water from selected wells during 2004 and 2005, with statistical comparisons of analytical results, Idaho 

National Laboratory, Idaho.—Continued

[See figures 1 and 2 for location of wells. Analytical results and F-pseudosigma estimated standard deviations are in milligrams per liter (mg/L) or micrograms 

per liter (mg/L). Shading indicates not statistically comparable at the 95-percent confidence level. Abbreviations: BHV, borehole volume; F-pseudos, 

F-pseudosigma estimated sample standard deviation; NA, not applicable; NC, not calculated; NS, not sampled; Repl., replicate sample; USGS, U.S. Geological 

Survey; Z-value, calculated using equation 1 (a Z-value less than or equal to 1.96 suggests statistical equivalence at the 95-percent confidence level); E, 

estimated; <, less than]

Well identifier Sample 

date

Inorganic constituent concentrations

Arsenic (mg/L) Lead (mg/L)

1-BHV F-pseudos 3-BHV F-pseudos Z-value 1-BHV F-pseudos 3-BHV F-pseudos Z-value

Area 2 10-05-04 NS NS NS NS NA NS NS NS NS NA

IET DISP 10-09-04 NS NS NS NS NA NS NS NS NS NA

Site 14 10-12-04 NS NS NS NS NA NS NS NS NS NA

Site 19 10-04-04 NS NS NS NS NA NS NS NS NS NA

TRA DISP 10-07-04 NS NS NS NS NA NS NS NS NS NA

USGS 4 10-14-04 NS NS NS NS NA NS NS NS NS NA

USGS 15 10-12-04 NS NS NS NS NA NS NS NS NS NA

WS INEL 1 10-27-04 NS NS NS NS NA NS NS NS NS NA

Arbor Test 04-25-05 NS NS NS NS NA NS NS NS NS NA

CFA LF 2-10 04-12-05 NS NS NS NS NA NS NS NS NS NA

No Name 1 04-11-05 2.384 0.552 2.14 0.538 0.32 < 0.08 NA < 0.08 NA 0

Site 9 04-28-05 NS NS NS NS NA NS NS NS NS NA

Site 17 04-27-05 NS NS NS NS NA NS NS NS NS NA

USGS 12 04-21-05 NS NS NS NS NA NS NS NS NS NA

USGS 22 04-25-05 NS NS NS NS NA NS NS NS NS NA

USGS 103 04-18-05 NS NS NS NS NA NS NS NS NS NA

USGS 119 03-31-05 NS NS NS NS NA NS NS NS NS NA

Well identifier Sample 

date

Inorganic constituent concentrations

Mercury (mg/L) Nickel (mg/L)

1-BHV F-pseudos 3-BHV F-pseudos Z-value 1-BHV F-pseudos 3-BHV F-pseudos Z-value

Area 2 10-05-04 NS NS NS NS NA NS NS NS NS NA

IET DISP 10-09-04 NS NS NS NS NA NS NS NS NS NA

Site 14 10-12-04 NS NS NS NS NA NS NS NS NS NA

Site 19 10-04-04 NS NS NS NS NA NS NS NS NS NA

TRA DISP 10-07-04 NS NS NS NS NA NS NS NS NS NA

USGS 4 10-14-04 NS NS NS NS NA NS NS NS NS NA

USGS 15 10-12-04 NS NS NS NS NA NS NS NS NS NA

WS INEL 1 10-27-04 NS NS NS NS NA NS NS NS NS NA

Arbor Test 04-25-05 NS NS NS NS NA NS NS NS NS NA

CFA LF 2-10 04-12-05 NS NS NS NS NA NS NS NS NS NA

No Name 1 04-11-05 < 0.010 NA < 0.010 NA 0 2.60 0.907 2.83 0.918 0.18

Site 9 04-28-05 NS NS NS NS NA NS NS NS NS NA

Site 17 04-27-05 NS NS NS NS NA NS NS NS NS NA

USGS 12 04-21-05 NS NS NS NS NA NS NS NS NS NA

USGS 22 04-25-05 NS NS NS NS NA NS NS NS NS NA

USGS 103 04-18-05 NS NS NS NS NA NS NS NS NS NA

USGS 119 03-31-05 NS NS NS NS NA NS NS NS NS NA

12  Well-Purging Effects on Water-Quality Results, Eastern Snake River Plain Aquifer, Idaho National Laboratory, Idaho
Table 2. Non-radioactive inorganic constituent concentrations and F-pseudosigma estimated sample standard deviations after purging 

1 and 3 borehole volumes of water from selected wells during 2004 and 2005, with statistical comparisons of analytical results, Idaho 

National Laboratory, Idaho.—Continued

[See figures 1 and 2 for location of wells. Analytical results and F-pseudosigma estimated standard deviations are in milligrams per liter (mg/L) or micrograms 

per liter (mg/L). Shading indicates not statistically comparable at the 95-percent confidence level. Abbreviations: BHV, borehole volume; F-pseudos, 

F-pseudosigma estimated sample standard deviation; NA, not applicable; NC, not calculated; NS, not sampled; Repl., replicate sample; USGS, U.S. Geological 

Survey; Z-value, calculated using equation 1 (a Z-value less than or equal to 1.96 suggests statistical equivalence at the 95-percent confidence level); E, 

estimated; <, less than]

Well identifier Sample 

date

Inorganic constituent concentrations

Thallium (mg/L) Zinc (mg/L)

1-BHV F-pseudos 3-BHV F-pseudos Z-value 1-BHV F-pseudos 3-BHV F-pseudos Z-value

Area 2 10-05-04 NS NS NS NS NA NS NS NS NS NA

IET DISP 10-09-04 NS NS NS NS NA NS NS NS NS NA

Site 14 10-12-04 NS NS NS NS NA NS NS NS NS NA

Site 19 10-04-04 NS NS NS NS NA NS NS NS NS NA

TRA DISP 10-07-04 NS NS NS NS NA NS NS NS NS NA

USGS 4 10-14-04 NS NS NS NS NA NS NS NS NS NA

USGS 15 10-12-04 NS NS NS NS NA NS NS NS NS NA

WS INEL 1 10-27-04 NS NS NS NS NA NS NS NS NS NA

Arbor Test 04-25-05 NS NS NS NS NA NS NS NS NS NA

CFA LF 2-10 04-12-05 NS NS NS NS NA NS NS NS NS NA

No Name 1 04-11-05 < 0.04 NA < 0.04 NA 0 < 0.60 NA < 0.060 NA 0

Site 9 04-28-05 NS NS NS NS NA NS NS NS NS NA

Site 17 04-27-05 NS NS NS NS NA NS NS NS NS NA

USGS 12 04-21-05 NS NS NS NS NA NS NS NS NS NA

USGS 22 04-25-05 NS NS NS NS NA NS NS NS NS NA

USGS 103 04-18-05 NS NS NS NS NA NS NS NS NS NA

USGS 119 03-31-05 NS NS NS NS NA NS NS NS NS NA

Organic Constituents

The NWQL also does not report standard deviations 

with analytical results for organic constituents. As a result, 

approximations of standard deviations were used when 

appropriate. The Organic Blind Sample Program (OBSP) uses 

a F-pseudosigma method similar to the method described 

for non-radioactive inorganic constituents to estimate the 

sample standard deviations for total organic carbon (TOC) 

measurements in water samples. The F-pseudosigma equation 

is available at http://bqs.usgs.gov/OBSP/WY05Plots/

TSbodyLC114TOTAL_ORGANIC_CARBON.html. 

Concentrations of TOC, F-pseudosigma estimated sample 

standard deviations, and calculated Z-values are provided in 

table 3. For purgeable organic compounds (POC’s), analytical 

results were less than the respective MRL’s for 61 sample pairs 

in each of 3 water samples. As a result, all 183 Z-values for 

POC’s were set to zero (table 3). 

Study Methods 13
Qualitative Evaluation of Well-Purging 

Effects on Water-Quality Results

A qualitative evaluation was initiated to determine if waterquality data collected during October-November 2003 from 30 

wells (in the RCRA-listed waste polygon) were consistent with 

water-quality data collected from the same wells since 1990. 

October-November 2003 water-quality data were collected at 

each of the 30 wells for each constituent included in the USGS’s 

routine sample-collection program and plotted on graphs (figs. 

3-32, at back of report) along with water-quality data collected 

since 1990. Water-quality data used to plot the constituent 

graphs are available at http://water.usgs.gov/nwis/. Graphic 

water-quality data for the 30 wells (figs. 3-32) were visually 

inspected to determine if apparent water-quality data trends met 

one of four criteria: (1) increasing concentrations continued to 

increase, or (2) decreasing concentrations continued to decrease, 

or (3) constant concentrations remained constant, or (4) 

October-November 2003 data were consistent with long-term 

ranges of water-quality data when no apparent concentration 

trends existed. If constituents met one of these criteria, the 

conclusion was that purging either 1 or 3 wellbore volumes 

from the well did not affect data comparability. 

Well identifier Sample 

date

Total organic carbon (mg/L) Purgeable organic compounds (mg/L)

1-BHV F-pseudos 3-BHV F-pseudos Z-value 1-BHV F-pseudos 3-BHV F-pseudos Z-value

Area 2 10-05-04 NS NS NS NS NA NS NS NS NS NA

IET DISP 10-09-04 NS NS NS NS NA NS NS NS NS NA

Site 14 10-12-04 <0.4 0.000 <0.4 0.000 0 NS NS NS NS NA

Site 19 10-04-04 NS NS NS NS NA NS NS NS NS NA

TRA DISP 10-07-04 NS NS NS NS NA NS NS NS NS NA

USGS 4 10-14-04 2.08 .354 1.358 .231 1.71 NS NS NS NS NA

USGS 15 10-12-04 NS NS NS NS NA NS NS NS NS NA

WS INEL 1 10-27-04 NS NS NS NS NA NS NS NS NS NA

Arbor Test 04-25-05 NS NS NS NS NA NS NS NS NS NA

CFA LF 2-10 04-12-05 2.53 .348 .52 .072 5.66 NS NS NS NS NA

No Name 1 04-11-05 <.4 .000 4.526 .623 2.82 161<MRL 261 = NA 161<MRL 261 = NA 361 = 0

Site 9 04-28-05 NS NS NS NS NA NS NS NS NS NA

Site 17 04-27-05 NS NS NS NS NA NS NS NS NS NA

USGS 12 04-21-05 5.76 .793 5.39 .741 0.34 161<MRL 261 = NA 161<MRL 261 = NA 361 = 0

USGS 22 04-25-05 NS NS NS NS NA NS NS NS NS NA

USGS 103 04-18-05 4.06 .559 1.94 .267 3.42 NS NS NS NS NA

USGS 119 03-31-05 NS NS NS NS NA 161<MRL 261 = NA 161<MRL 261 = NA 361 = 0

1

Sixty-one compounds are less than the minimum reporting levels.

2

Calculation of F-pseudosigma estimated sample standard deviation is not applicable for 61 compounds.

3

Z-value is set to 0 for 61 compounds.

Table 3. Total organic carbon and purgeable organic compound concentrations and F-pseudosigma estimated sample standard 

deviations after purging 1 and 3 borehole volumes of water from selected wells during 2004 and 2005, with statistical comparisons of 

analytical results, Idaho National Laboratory, Idaho.

[See figures 1 and 2 for location of wells. Analytical results and F-pseudosigma uncertainties are in milligrams per liter (mg/L) or micrograms per liter (mg/L). 

Shading indicates not statistically comparable at the 95-percent confidence level. Z-value, calculated using equation 1 (a Z-value less than or equal to 1.96 

suggests statistical equivalence at the 95-percent confidence level). Abbreviations: BHV, borehole volume; F-pseudos, F-pseudosigma (estimated sample 

standard deviation reported as 1 sigma); MRL, minimum reporting level; NA, not applicable; NS, not sampled; USGS, U.S. Geological Survey; <, less than]

Constituent data examples that met one of the above 

criteria include:

Sulfate concentrations for well USGS 34 (fig. 4) and 

chloride, nitrate, and sodium concentrations for well 

USGS 40 (fig. 10) exhibited short-term increasing trends 

since about 2000 and corresponding concentrations for 

the October-November 2003 samples followed the same 

pattern; 

Tritium concentrations for well USGS 37 (fig. 7) 

exhibited a decreasing trend since 1990 and the tritium 

concentration for the October-November 2003 sample 

followed the same pattern; 

Fluoride concentrations for well USGS 77 (fig. 23) 

since 1990 and sulfate concentrations for well USGS 

111 (fig. 26) since about 1997 exhibited relatively 

constant trends and corresponding concentrations for 

the October-November 2003 samples followed the 

same pattern; and

Nitrate, sodium, and strontium-90 concentrations for 

well USGS 47 (fig. 17) during October-November 

2003 increased from previous sample concentrations, 

but were within the historical range of concentrations 

for those constituents.

•

•

•

•

14  Well-Purging Effects on Water-Quality Results, Eastern Snake River Plain Aquifer, Idaho National Laboratory, Idaho
Quantitative Evaluation of Well-Purging 

Effects on Water-Quality Results

A quantitative evaluation was initiated to determine 

if water-quality data from samples collected after purging 

1 and 3 wellbore volumes of water were statistically 

equivalent at a 95-percent confidence level. Water samples 

were collected from 17 INL wells with long purge times 

(figs. 1, 2). One quality assurance replicate sample also was 

collected for evaluation. Equation 1 was used to evaluate 

the statistical equivalence of 337 constituent pairs using 

(1) standard deviations reported by the analytical laboratory 

for radiochemical measurements, and (2) estimated standard 

deviations for non-radioactive constituents. Regression 

equations used to calculate the F-pseudosigma estimates 

of standard deviation are available at http://bqs.usgs.gov/

bsp/regress.htm. Equation 1 also was used to re-evaluate 63 

constituent pairs generated from water samples collected at 

11 wells (figs. 1, 2) by Bartholomay (1993). Bartholomay 

collected samples from 10 wells during spring and autumn and 

at the TRA DISP well (fig. 1) during autumn after purging 1, 

2, and 3 wellbore volumes from the wells. Analytical results 

for the samples, standard deviations, and calculated Z-values 

are provided in tables 1-4. If the Z-value was less than 1.96, 

the sample pair was considered equivalent at the 95-percent 

confidence level.

Samples collected for this study after purging 1 and 3 

wellbore volumes of water from a well were considered a 

sample pair. Sample pairs from the 17 wells along with the 

quality assurance replicate sample from USGS 22 (fig. 1, 

tables 1-3) generated 337 constituent pairs for evaluation using 

equation 1. Z-values for 331 pairs (98.2 percent) were less 

than 1.96 and were considered equivalent (tables 1-3).

Samples collected by Bartholomay (1993) after purging 

1, 2, and 3 wellbore volumes were analyzed for tritium and 

strontium-90 and the results were compared using a statistical 

technique derived from a test method recommended by 

the American Society for Testing and Materials (1988). To 

consider the Bartholomay (1993) results in this study, equation 

1 was used to re-evaluate his tritium and strontium-90 data. 

Samples collected by Bartholomay (1993) after purging 1 

and 3, 1 and 2, and 2 and 3 wellbore volumes of water from a 

well were considered sample pairs. The 63 sample pairs from 

the 11 wells generated 126 constituent pairs for evaluation. 

Z-values for 120 pairs (95.2 percent) were less than 1.96 and 

were considered equivalent (table 4). A further breakdown 

of data from Bartholomay (1993) indicates that statistical 

equivalence is slightly stronger in autumn (97 percent) than 

in spring (93.3 percent). Additionally, agreement is slightly 

better between 1 and 2 wellbore volumes (97.6 percent) than 

between 1 and 3 wellbore volumes (95.2 percent) or between 2 

and 3 wellbore volumes (92.8 percent).

The visual inspection of 322 constituent plots in figs. 

3-32 indicated that nearly all plots met one or two of the 

four criteria identified for data comparability. Six constituent 

plots and three field-measurement plots did not meet any 

of the criteria. These included sodium concentrations for 

wells USGS 57 and 115 (figs. 22, 30), sulfate concentrations 

for wells USGS 42, 43, and 57 (figs. 12, 13, 22), pH 

measurements for wells USGS 47 and 112 (figs. 17, 27), 

temperature measurements for well USGS 111 (fig. 26), and 

cesium-137 concentrations for well USGS 113 (fig. 28). 

In each instance, concentrations or measurements for the 

October-November 2003 samples were 14-year minimums 

and did not follow any trend. All cesium-137 concentrations 

at well USGS 113 for the 10-year period of record were 

less than the radionuclide reporting level of three times the 

standard deviation and were within two standard deviations of 

each other (fig. 28). As a result, cesium-137 for the OctoberNovember sample is considered comparable to historical data. 

When cesium-137 is included with the 313 constituent plots or 

measurements that met one or more of the acceptance criteria 

for data comparability, 97.5 percent were comparable. 

The remaining eight constituent or measurement plots 

did not follow any trend or fall within the historical range 

of water-quality data and were not considered comparable; 

however, concentrations or measurements did plot near the 

mean values for the period of record. The October-November 

2003 pH measurements (7.6 pH units at well USGS 47 and 7.5 

pH units at well USGS 112) (figs. 17, 27) were within 0.1 and 

0.2 pH units of the previous minimums (7.7 and 7.7 pH units 

in 2001 and 1994, respectively) and within 0.3 and 0.4 pH 

units of the respective mean concentrations (7.9 and 7.9 pH 

units). The October-November 2003 temperature measurement 

of 12.5oC at well USGS 111 (fig. 26) was within 0.2oC of the 

previous minimum (12.7oC in 1995) and within 0.8oC of the 

13-year mean (13.3oC). The October-November 2003 sodium 

concentrations (30 mg/L at well USGS 57 and 10 mg/L at 

well USGS 115) (figs. 22, 30) were within 8 and 3 mg/L of 

the previous minimums (38 and 13 mg/L in 2001 and 1991, 

respectively) and within 27 and 4 mg/L of the respective mean 

concentrations (57 and 14 mg/L). The October-November 

2003 sulfate concentrations (22 mg/L at well USGS 42, 22 

mg/L at well USGS 43, and 27 mg/L at well USGS 57) (figs. 

12, 13, 22) were within 2, 1, and 2 mg/L of the previous 

minimums (24, 23, and 29 mg/L in 2001, 1998, and 2000, 

respectively) and within 3, 2, and 4 mg/L of the respective 

mean concentrations (25, 24, and 31 mg/L).

Because of the good qualitative agreement between 

the October-November 2003 water-quality data and the 

corresponding historical water-quality data, there is no 

indication that the change from purging 3 wellbore volumes 

of water to purging 1 wellbore volume of water (for the 30 

wells in the RCRA listed-waste polygon) has an effect on the 

comparability of water-quality data. 

Quantitative Evaluation of Well-Purging Effects on Water-Quality Results 15
Well identifier Sample 

date

Tritium concentrations

1-BHV SD 2-BHV SD 3-BHV SD

Sample pairs

Z 1-3 BHV Z 1-2 BHV Z 2-3 BHV

Site 9 04-09-91 10 160 -110 160 50 160 0.18 0.53 0.71

09-27-91 10 170 10 170 -50 170 .25 0 .25

Site 14 04-24-91 50 160 170 170 -20 160 .31 .51 .81

10-18-91 0 200 100 200 -30 170 .11 .35 .50

Site 19 04-02-91 110 160 -40 160 -50 160 .71 .66 .04

10-22-91 10 170 0 200 10 170 0 .04 .04

TRA DISP 10-30-91 7,700 400 7,300 400 6,900 300 1.60 .71 .80

USGS 38 04-22-91 28,600 700 28,600 700 27,600 700 1.01 0 1.01

10-03-91 25,600 700 25,700 700 26,300 700 .71 .10 .61

USGS 59 04-04-91 5,300 300 6,300 300 4,900 300 .94 2.36 3.30

10-21-91 19,100 600 18,900 600 19,300 600 .24 .24 .47

USGS 82 03-27-91 1,100 200 1,200 200 1100 200 0 .35 .35

10-23-91 150 170 150 170 100 200 .19 0 .19

USGS 83 03-25-91 -50 160 -50 160 20 160 .31 0 .31

10-01-91 100 200 -80 170 0 200 .35 .69 .30

USGS 107 04-22-91 110 160 60 160 -70 160 .80 .22 .57

09-30-91 100 200 -80 170 0 170 .38 .69 .33

USGS 110 03-26-91 210 170 -170 150 20 160 .81 1.68 .87

10-07-91 -150 160 100 200 -30 170 .51 .98 .50

USGS 119 04-19-91 70 160 150 170 0 160 .31 .34 .64

10-15-91 150 170 -130 160 -140 160 1.24 1.20 .04

Table 4. Tritium and strontium-90 concentrations, and associated estimated standard deviations after purging 1, 2, and 3 borehole 

volumes of water from selected wells during 1991, with statistical comparisons of analytical results, Idaho National Laboratory, Idaho.

[See figures 1 and 2 for location of wells. Analytical results and estimated standard deviations are in picocuries per liter. Shading indicates not statistically 

comparable at the 95-percent confidence level. Sample pairs from Bartholomay (1993, table 3); Abbreviations: BHV, borehole volume; SD, estimated standard 

deviation reported as 1-sigma; USGS, U.S. Geological Survey; Z, Z-value calculated using equation 1 (a Z-value less than or equal to 1.96 indicates statistical 

equivalence at the 95-percent confidence level)]

Well identifier Sample 

date

Strontium-90 concentrations

1-BHV SD 2-BHV SD 3-BHV SD

Sample pairs

Z 1-3 BHV Z 1-2 BHV Z 2-3 BHV

Site 9 04-09-91 -0.2 1.5 0.7 1.6 -0.8 1.5 0.28 0.41 0.68

09-27-91 -5.0 2.0 -6.0 2.0 -6.0 2.0 .35 .35 0

Site 14 04-24-91 -1.6 1.8 0 2.0 0 2.0 .59 .59 0

10-18-91 0 2.0 1.0 2.0 1.3 2.4 .42 .35 .10

Site 19 04-02-91 1.7 2.0 3.0 2.0 1.1 1.9 .22 .46 .69

10-22-91 0 2.0 4.0 2.0 -1.3 2.3 .43 1.41 1.74

TRA DISP 10-30-91 -.9 1.7 .8 1.6 -0.4 1.5 .22 .73 .55

USGS 38 04-22-91 26.0 3.0 28.0 3.0 29.0 3.0 .71 .47 .24

10-03-91 23.0 3.0 27.0 5.0 9.0 3.0 3.30 .69 3.09

USGS 59 04-04-91 13.0 3.0 16.0 3.0 13.0 3.0 0 .71 .71

10-21-91 18.0 3.0 17.0 3.0 14.0 2.0 1.11 .24 .83

USGS 82 03-27-91 -3.1 1.7 0 2.0 8.0 2.0 4.23 1.18 2.83

10-23-91 -1.0 2.0 -1.2 2.1 -2.0 2.0 .35 .07 .28

USGS 83 03-25-91 -3.7 1.5 -4.4 1.5 -3.8 1.5 .05 .33 .28

10-01-91 -1.4 1.9 -2.0 2.0 -2.0 2.0 .22 .22 0

USGS 107 04-22-91 -1.0 2.0 -1.0 2.0 -1.0 2.0 0 0 0

09-30-91 1.0 2.0 1.0 2.0 2.0 2.0 .35 0 .35

USGS 110 03-26-91 -3.6 1.7 -1.2 2.0 -3.0 2.0 .23 .91 .64

10-07-91 -1.0 2.0 -1.0 2.2 0 2.0 .35 0 .34

USGS 119 04-19-91 .7 1.7 0 1.6 4.0 2.0 1.26 .30 1.56

10-15-91 -1.0 2.0 -3.0 2.0 1.4 2.1 .83 .71 1.52

16  Well-Purging Effects on Water-Quality Results, Eastern Snake River Plain Aquifer, Idaho National Laboratory, Idaho
When all 1 and 3 wellbore volume constituent pairs 

were considered together, 371 of 379 pairs (97.9 percent) 

were statistically equivalent. When the 1 and 2 or the 2 and 3 

wellbore volume constituent pairs were included, 451 of 463 

(97.4 percent) were statistically equivalent.

Because of the good quantitative agreement between 

constituent pairs, there is no indication that changing from 

purging 3 wellbore volumes of water to purging 1 wellbore 

volume of water effected comparability of water-quality data. 

On the basis of a smaller data set from Bartholomay (1993), it 

appears that purging 2 wellbore volumes also is an acceptable 

practice for data comparability.

Observations

Comparability of water-quality data determined from 

both the qualitative evaluation (97.5 percent comparable) and 

the quantitative evaluation (97.9 percent comparable) indicates 

that the change from purging 3 to 1 wellbore volumes had 

no discernible effect on comparability of water-quality data 

at the INL. However, the qualitative evaluation was limited 

by a small data set. Only October-November 2003 data were 

available for comparison to historical data. 

This comparability of water-quality data is not surprising 

considering the character of the ESRPA. The ESRPA is 

mostly an unconfined aquifer and chemical equilibrium with 

atmospheric gases (such as dissolved oxygen and dissolved 

carbon dioxide) is maintained in the ground water. Carbon 

dioxide establishes a buffering process that stabilizes pH in the 

ESRPA (figs. 3-32). Similarly, the ESRPA is saturated with 

dissolved oxygen except for areas where organic compounds 

were introduced by waste disposal. Dissolved oxygen 

maintains oxidizing conditions in the ground water and 

stabilizes oxidation-reduction processes in the aquifer, which 

favors development of the oxidized species such as sulfate 

and nitrate. The combination of these conditions decreases the 

tendency of ground water to undergo rapid chemical change 

because water standing in an open borehole in the unconfined 

ESRPA is chemically the same as water in the aquifer, and 

both are in equilibrium with the atmosphere.

Barcelona and others (2005) found that water chemistry 

from wells in high-permeability materials stabilized after 

purging only one-half wellbore volume of water from a well. 

For both the high- and low-permeability wells, stabilization 

of field water-quality parameters was the principal indicator 

of chemical stability, one of the ESRPA sample-collection 

criteria. The ESRPA generally is a high-permeability aquifer, 

which likely accounts for the comparability of water-quality 

data. In the Barcelona and others (2005) study, small flow 

rates (<0.5 L/min) were used for purging and sampling. As 

a result, their conclusions are not directly comparable to the 

conclusions of this study.

Summary and Conclusions

This report presents qualitative and quantitative 

comparisons of water-quality data from the Idaho National 

Laboratory to determine if the change from purging 3 wellbore 

volumes to 1 wellbore volume has a discernible effect on the 

comparability of data. Historical water-quality data for 30 

wells were visually compared to water-quality data collected 

after purging only 1 wellbore volume of water from the same 

30 wells. Of the 322 qualitatively examined constituent plots, 

97.5 percent met one or more of the criteria established for 

determining data comparability. A simple statistical equation 

to determine if water-quality data collected from 17 wells with 

long purge times (after pumping 1 and 3 wellbore volumes of 

water) were statistically the same at the 95-percent confidence 

level indicated that 98.2 percent of 337 constituent pairs were 

equivalent. The same simple statistical equation to determine 

if water-quality data collected during a previous study from 11 

wells at the Idaho National Laboratory with long purge times 

(after pumping 1, 2, and 3 wellbore volumes) were statistically 

the same at the 95-percent confidence level indicated that 95.2 

percent of 126 constituent pairs were equivalent. When all 

1 and 3 wellbore volume constituent pairs were considered 

together, 371 of 379 pairs (97.9 percent) were statistically 

equivalent.

Comparability of water-quality data determined 

from both the qualitative (97.5 percent comparable) and 

quantitative evaluations (97.9 percent comparable) indicated 

that the change from purging 3 to 1 wellbore volumes had no 

discernible effect on comparability of water-quality data at the 

Idaho National Laboratory. However, the qualitative evaluation 

was limited by a small data set. Only October-November 2003 

data were available for comparison to historical data.

Summary and Conclusions 17
Acknowledgments

The author is grateful to Carolyn T. Moores, Matthew J. 

Gilbert, Betty J. Tucker, Mark S. Vance, and Amy J. 

Wehnke, USGS, for designing and testing containerization 

equipment and for collecting samples for this study and Roy 

C. Bartholomay, USGS and L. Flint Hall, State of Idaho 

DEQ-INL Oversight and Radiation Control Program for 

technically reviewing the manuscript.

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ground water from 39 selected sites with an evaluation 

of associated quality assurance data, Idaho National 

Engineering and Environmental Laboratory and vicinity, 

Idaho: U.S. Geological Survey Open-File Report 99-246 

(DOE/ID-22159), 58 p.

Maloney, T.J., Ludke, A.S., and Kritzman, T.L., 1993, Quality 

assurance for routine water analysis in the laboratories 

of the U.S. Geological Survey for water year 1990: U.S. 

Geological Survey Water-Resources Investigations Report 

93-4082, 145 p.

Mann, L.J., 1986, Hydraulic properties of rock units and 

chemical quality of water for INEL-1—A 10,365-ft 

deep test hole drilled at the Idaho National Engineering 

Laboratory, Idaho: U.S. Geological Survey Water-Resources 

Investigations Report 86-4020 (DOE/ID-22070), 23 p.

Mundorff, M.J., Crosthwaite, E.G., and Kilburn, Chabot, 

1964, Ground water for irrigation in the Snake River Basin 

in Idaho: U.S. Geological Survey Water-Supply Paper 1654, 

224 p.

Robin, M.J.L., and Gilham, R.W., 1987, Field evaluation of 

well purging procedures: Ground Water Monitoring Review, 

v. 7, no. 3, p. 85-93.

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

by the U.S. Geological Survey National Water Quality 

Laboratory—Determination of volatile organic compounds 

in water by purge and trap capillary gas chromatograph/

mass spectrometry: U.S. Geological Survey Open-File 

Report 94-708, 26 p.

Skougstad, M.W., Fishman, M.J., Friedman, L.C., Erdmann, 

D.E., and Duncan, S.S., eds., 1979, Methods for 

determination of inorganic substances in water and fluvial 

sediments: U.S. Geological Survey Techniques of WaterResources Investigations, book 5, chap. A1, 626 p. 

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

services catalog: U.S. Geological Survey Open-File Report 

95-352, 120 p. 

U.S. Department of Energy, 1995, Radiochemistry manual, 

revision 10: Idaho Falls, Idaho, U.S. Department of Energy, 

Radiological and Environmental Sciences Laboratory 

[variously paged].

U.S. Environmental Protection Agency, 1986, RCRA 

ground-water monitoring technical enforcement guidance 

document: U.S. Environmental Protection Agency, Office 

of Waste Programs Enforcement, Office of Solid Waste and 

Emergency Response, OSWER-9950.1, 208 p.

U.S. Geological Survey, variously dated, National field manual 

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Survey Techniques of Water-Resources Investigations, 

book 9, chaps. A1-A9, available at http://pubs.water.usgs.

gov/twri9A.

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New York, McGraw-Hill Book Company, 415 p.

Wershaw, R.L., Fishman, M.J., Grabbe, R.R., and Lowe, L.E., 

1987, Methods for the determination of organic substances 

in water and fluvial sediments: U.S. Geological Survey 

Techniques of Water-Resources Investigations, book 5, 

chap. A3, 80 p. 

Whitehead, R.L., 1986, Geohydrological framework of 

the Snake River Plain, Idaho and eastern Oregon: U.S. 

Geological Survey Hydrologic Investigations Atlas HA-681, 

3 sheets, scale 1:1,000,000.

Wilde, F.D., Radtke, D.B., Gibs, Jacob, and Iwatsubo, R.T., 

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paged]. 

Williams, L.M., 1996, Evaluation of quality assurance/quality 

control data collected by the U.S. Geological Survey for 

water-quality activities at the Idaho National Engineering 

Laboratory, Idaho, 1989 through 1993: U.S. Geological 

Survey Water-Resources Investigations Report 96-4148 

(DOE/ID-22129), 115 p.

References Cited 19
ID9HZ02_fig03a-d

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

A. C.

D.

B.

0

2

4

6

8

10

12

14

16

FIELD MEASUREMENT OR

CONSTITUENT CONCENTRATION

0

5

10

15

20

25

30

35

CONSTITUENT CONCETRATION, 

IN MILLIGRAMS PER LITER

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

-10

-8

-6

-4

-2

0

2

4

6

8

10

STRONTIUM-90 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

TRITIUM AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

SULFATE

TEMPERATURE, IN DEGREES CELCIUS

pH, UNITS

SPECIFIC CONDUCTANCE/100,

 MICROSIEMENS PER CENTIMETER

EXPLANATION

CHLORIDE

SODIUM

NITRATE, MILLIGRAMS PER LITER

REPORTING LEVEL, 3-SIGMA

2-SIGMA ERROR

Figure 3. Water-quality data for well USGS 20, 1990-2003, with corresponding data for October-November 2003, Idaho 

National Laboratory, Idaho.

20 Well-Purging Effects on Water-Quality Results, Eastern Snake River Plain Aquifer, Idaho National Laboratory, Idaho
ID9HZ02_fig04a-h

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

A. E.

F.

G.

H.

B.

C.

D.

0

5

10

15

20

25

30

35

40

0

5

10

15

20

25

30

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

-15

-10

-5

0

5

10

15

-150

-100

-50

0

50

100

150

CESIUM-137 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER -0.10

-0.08

-0.06

-0.04

-0.02

0.00

0.02

0.04

0.06

0.08

0.10

PLUTONIUM-238 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER -0.08

-0.06

-0.04

-0.02

0.00

0.02

0.04

0.06

0.08

PLUTONIUM-239, -240 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER -0.10

-0.05

0.00

0.05

0.10

0.15

FIELD MEASUREMENT OR

CONSTITUENT CONCENTRATION

CONSTITUENT CONCETRATION, IN

MILLIGRAMS PER LITER

TRITIUM AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

STRONTIUM-90 AND 2-SIGMA ERROR, IN

PICOCURIES PER LITER

AMERICIUM-241 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

SULFATE, IN MILLIGRAMS PER LITER

TEMPERATURE, IN DEGREES CELCIUS

pH, UNITS

SPECIFIC CONDUCTANCE/100,

 MICROSIEMENS PER CENTIMETER

EXPLANATION

CHLORIDE

SODIUM

NITRATE

REPORTING LEVEL, 3-SIGMA

2-SIGMA ERROR

Figure 4. Water-quality data for well USGS 34, 1990-2003, with corresponding data for October-November 2003, Idaho 

National Laboratory, Idaho.

Figures  21
ID9HZ02_fig04i-l

1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

I. K.

L.

J.

-2

-1

0

1

2

3

4

GROSS ALPHA RADIOACTIVITY

AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

PLUTONIUM-239

REPORTING STANDARD

0

5

10

15

20

25

GROSS BETA RADIOACTIVITY

AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

CESIUM-137 REPORTING STANDARD

0

5

10

15

20

25

30

35

CONSTITUENT CONCENTRATION

0.0

0.5

1.0

1.5

2.0

2.5

3.0

CONSTITUENT CONCENTRATION

TOTAL DISSOLVED CHROMIUM,

 IN MICROGRAMS PER LITER

FLUORIDE, IN MILLIGRAMS PER LITER

TOTAL ORGANIC CARBON,

IN MILLIGRAMS PER LITER

EXPLANATION

1,1,1-TRICHLOROETHANE,

IN MICROGRAMS PER LITER

REPORTING LEVEL, 3-SIGMA

2-SIGMA ERROR

Figure 4. Continued.

22  Well-Purging Effects on Water-Quality Results, Eastern Snake River Plain Aquifer, Idaho National Laboratory, Idaho
ID9HZ02_fig05a-d

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

A.

B.

C.

D.

0

2

4

6

8

10

12

14

0

5

10

15

20

25

30

35

40

45

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

9,000

10,000

FIELD MEASUREMENT OR

CONSTITUENT CONCENTRATION

CONSTITUENT CONCETRATION, IN

MILLIGRAMS PER LITER

TRITIUM AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

STRONTIUM-90 AND 2-SIGMA ERROR, IN

PICOCURIES PER LITER

-15

-10

-5

0

5

10

15

20

SULFATE

TEMPERATURE, IN DEGREES CELCIUS

pH, UNITS

SPECIFIC CONDUCTANCE/100,

 MICROSIEMENS PER CENTIMETER

EXPLANATION

CHLORIDE

SODIUM

NITRATE, IN MILLIGRAMS PER LITER

REPORTING LEVEL, 3-SIGMA

2-SIGMA ERROR

Figure 5. Water-quality data for well USGS 35, 1990-2003, with corresponding data for October-November 2003, Idaho 

National Laboratory, Idaho.

Figures  23
ID9HZ02_fig06a-d

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

A.

B.

C.

D.

0

2

4

6

8

10

12

14

16

FIELD MEASUREMENT OR

CONSTITUENT CONCENTRATION

0

10

20

30

40

50

60

70

80

90

CONSTITUENT CONCENTRATIONS, IN

MILLIGRAMS PER LITER

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

16,000

18,000

TRITIUM AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

0

5

10

15

20

25

30

STRONTIUM-90 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

SULFATE

TEMPERATURE, IN DEGREES CELCIUS

pH, UNITS

SPECIFIC CONDUCTANCE/100,

 MICROSIEMENS PER CENTIMETER

EXPLANATION

CHLORIDE

SODIUM

NITRATE, IN MILLIGRAMS PER LITER

REPORTING LEVEL, 3-SIGMA

2-SIGMA ERROR

Figure 6. Water-quality data for well USGS 36, 1990-2003, with corresponding data for October-November 2003, Idaho 

National Laboratory, Idaho.

24  Well-Purging Effects on Water-Quality Results, Eastern Snake River Plain Aquifer, Idaho National Laboratory, Idaho
ID9HZ02_fig07a-h

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

A. E.

F.

G.

H.

B.

C.

D.

0

5

10

15

20

25

30

35

FIELD MEASUREMENT OR

CONSTITUENT ONCENTRATION

0

20

40

60

80

100

120

140

160

CONSTITUENT CONCENTRATION,

IN MILLIGRAMS PER LITER

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

TRITIUM AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

-10

-5

0

5

10

15

20

25

30

STRONTIUM-90 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

-150

-100

-50

50

100

150

CESIUM-137 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

0

-0.06

-0.04

-0.02

0.00

0.02

0.04

0.06

0.08

0.10

PLUTONIUM-238 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

-0.05

-0.04

-0.03

-0.02

-0.01

0.00

0.01

0.02

0.03

0.04

0.05

0.06

PLUTONIUM-239, -240 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER -0.05

0.00

0.05

0.10

0.15

0.20

AMERICIUM-241 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER -0.10

SULFATE, IN MILLIGRAMS PER LITER

TEMPERATURE, IN DEGREES CELCIUS

pH, UNITS

SPECIFIC CONDUCTANCE/100,

 MICROSIEMENS PER CENTIMETER

EXPLANATION

CHLORIDE

SODIUM

NITRATE

REPORTING LEVEL, 3-SIGMA

2-SIGMA ERROR

Figure 7. Water-quality data for well USGS 37, 1990-2003, with corresponding data for October-November 2003, Idaho 

National Laboratory, Idaho.

Figures  25
ID9HZ02_fig08a-h

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

G.

H.

A. E.

F.

B.

C.

D.

0

2

4

6

8

10

12

14

16

FIELD MEASUREMENT OR

CONSTITUENT CONCENTRATION

0

20

40

60

80

100

120

140

160

180

200

CONSTITUENT CONCENTRATION, IN

MILLIGRAMS PER LITER

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

TRITIUM AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

0

5

10

15

20

25

30

35

40

STRONTIUM-90 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

-150

-100

-50

0

50

100

150

200

CESIUM-137 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER -0.10

-0.08

-0.06

-0.04

-0.02

0.00

0.02

0.04

0.06

0.08

0.10

PLUTONIUM-238 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER -0.08

-0.06

-0.04

-0.02

0.00

0.02

0.04

0.06

0.08

PLUTONIUM-239, -240 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER -0.15

-0.10

-0.05

0.00

0.05

0.10

0.15

AMERICIUM-241 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

SULFATE

TEMPERATURE, IN DEGREES CELCIUS

pH, UNITS

SPECIFIC CONDUCTANCE/100,

 MICROSIEMENS PER CENTIMETER

EXPLANATION

CHLORIDE

SODIUM

NITRATE, IN MILLIGRAMS PER LITER

REPORTING LEVEL, 3-SIGMA

2-SIGMA ERROR

Figure 8. Water-quality data for well USGS 38, 1990-2003, with corresponding data for October-November 2003, Idaho 

National Laboratory, Idaho.

26  Well-Purging Effects on Water-Quality Results, Eastern Snake River Plain Aquifer, Idaho National Laboratory, Idaho
ID9HZ02_fig08i-l

PLUTONIUM-239 REPORTING STANDARD

1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

I.

J.

K.

L.

-2.0

-1.0

0.0

1.0

2.0

3.0

4.0

5.0

GROSS ALPHA RADIOACTIVITY

AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

CESIUM-137 REPORTING STANDARD

0

10

20

30

40

50

60

70

80

GROSS BETA RADIOACTIVITY

AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

0

2

4

6

8

10

12

14

16

CONSTITUENT CONCENTRATION

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

CONSTITUENT CONCENTRATION

TOTAL DISSOLVED CHROMIUM,

 MICROGRAMS PER LITER

FLUORIDE, MILLIGRAMS PER LITER

TOTAL ORGANIC CARBON,

 MILLIGRAMS PER LITER

EXPLANATION

1,1,1-TRICHLOROETHANE,

 IN MICROGRAMS PER LITER

REPORTING LEVEL, 3-SIGMA

2-SIGMA ERROR

NATIONAL WATER QUALITY LABORATORY 

REPORTED CONCENTRATION

AS LESS THAN

0.4 MILLIGRAM PER LITER

Figure 8. Continued.

Figures  27
ID9HZ02_fig09a-d

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

B.

A. C.

D.

0

2

4

6

8

10

12

14

0

10

20

30

40

50

60

70

80

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

-10

-8

-6

-4

-2

0

2

4

6

8

10

SULFATE

TEMPERATURE, IN DEGREES CELCIUS

pH, UNITS

SPECIFIC CONDUCTANCE/100,

 MICROSIEMENS PER CENTIMETER

EXPLANATION

CHLORIDE

SODIUM

NITRATE, IN MILLIGRAMS PER LITER

REPORTING LEVEL, 3-SIGMA

2-SIGMA ERROR

FIELD MEASUREMENT OR

CONSTITUENT CONCENTRATION

CONSTITUENT CONCETRATION, IN

MILLIGRAMS PER LITER

TRITIUM AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER STRONTIUM-90 AND 2-SIGMA ERROR, IN PICOCURIES PER LITER

Figure 9. Water-quality data for well USGS 39, 1990-2003, with corresponding data for October-November 2003, Idaho 

National Laboratory, Idaho.

28  Well-Purging Effects on Water-Quality Results, Eastern Snake River Plain Aquifer, Idaho National Laboratory, Idaho
ID9HZ02_fig10a-h

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

A. E.

B. F.

C.

G.

D.

H.

0

5

10

15

20

25

30

35

40

45

0

5

10

15

20

25

30

35

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

16,000

0

5

10

15

20

25

30

35

40

45

50

-150

-100

-50

0

50

100

150

200

-0.10

-0.08

-0.06

-0.04

-0.02

0.00

0.02

0.04

0.06

0.08

0.10

-0.08

-0.06

-0.04

-0.02

0.00

0.02

0.04

0.06

0.08

0.10

-0.10

-0.05

0.00

0.05

0.10

0.15

0.20

PLUTONIUM-239, -240 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

AMERICIUM-241 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

TRITIUM AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

STRONTIUM-90 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

FIELD MEASUREMENT OR

CONSTITUENT CONCENTRATION

CONSTITUENT CONCETRATION, 

IN MILLIGRAMS PER LITER

SULFATE, IN MILLIGRAMS PER LITER

TEMPERATURE, IN DEGREES CELCIUS

pH, UNITS

SPECIFIC CONDUCTANCE/100,

 MICROSIEMENS PER CENTIMETER

EXPLANATION

CHLORIDE

SODIUM

NITRATE

REPORTING LEVEL, 3-SIGMA

2-SIGMA ERROR

CESIUM-137 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

PLUTONIUM-238 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

Figure 10. Water-quality data for well USGS 40, 1990-2003, with corresponding data for October-November 2003, Idaho 

National Laboratory, Idaho.

Figures  29
ID9HZ02_fig11a-d

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

A. C.

D.

B.

0

5

10

15

20

25

30

35

0

5

10

15

20

25

30

35

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

9,000

0

5

10

15

20

25

30

TRITIUM AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

STRONTIUM-90 AND 2-SIGMA ERROR, IN

PICOCURIES PER LITER

SULFATE

TEMPERATURE, IN DEGREES CELCIUS

pH, UNITS

SPECIFIC CONDUCTANCE/100,

 MICROSIEMENS PER CENTIMETER

EXPLANATION

CHLORIDE, IN MILLIGRAMS PER LITER

SODIUM

NITRATE

REPORTING LEVEL, 3-SIGMA

2-SIGMA ERROR

FIELD MEASUREMENT OR

CONSTITUENT CONCENTRATION

CONSTITUENT CONCETRATION, IN

MILLIGRAMS PER LITER

Figure 11. Water-quality data for well USGS 41, 1990-2003, with corresponding data for October-November 2003, Idaho 

National Laboratory, Idaho.

30 Well-Purging Effects on Water-Quality Results, Eastern Snake River Plain Aquifer, Idaho National Laboratory, Idaho
ID9HZ02_fig12a-d

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

A.

B.

C.

D.

0

5

10

15

20

25

30

35

0

5

10

15

20

25

30

-1,000

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

9,000

0

0

5

10

15

20

25

30

35

SULFATE

TEMPERATURE, IN DEGREES CELCIUS

pH, UNITS

SPECIFIC CONDUCTANCE/100,

 MICROSIEMENS PER CENTIMETER

EXPLANATION

CHLORIDE, IN MILLIGRAMS PER LITER

SODIUM

NITRATE

REPORTING LEVEL, 3-SIGMA

2-SIGMA ERROR

FIELD MEASUREMENT OR

CONSTITUENT CONCENTRATION

CONSTITUENT CONCETRATION, IN

MILLIGRAMS PER LITER

TRITIUM AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

STRONTIUM-90 AND 2-SIGMA ERROR, IN

PICOCURIES PER LITER

Figure 12. Water-quality data for well USGS 42, 1990-2003, with corresponding data for October-November 2003, Idaho 

National Laboratory, Idaho.

Figures  31
ID9HZ02_fig13a-h

-0.05

0.00

0.05

0.10

0.15

0.20

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

G.

H.

A. E.

F.

B.

C.

D.

0

5

10

15

20

25

30

0

5

10

15

20

25

30

35

40

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

-10

-5

0

5

10

15

20

STRONTIUM-90 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

-150

-100

-50

0

50

100

150

-0.06

-0.04

-0.02

0.00

0.02

0.04

0.06

0.08

0.10

-0.20

-0.15

-0.10

-0.05

0.00

0.05

0.10

0.15

0.20

PLUTONIUM-239, -240 AND 2-SIGMA

ERROR, IN PICOCURIES PER LITER

AMERICIUM-241 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

CESIUM-137 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER PLUTONIUM-238 AND 2-SIGMA

ERROR, IN PICOCURIES PER LITER

SULFATE, IN MILLIGRAMS PER LITER

TEMPERATURE, IN DEGREES CELCIUS

pH, UNITS

SPECIFIC CONDUCTANCE/100,

 MICROSIEMENS PER CENTIMETER

EXPLANATION

CHLORIDE

SODIUM

NITRATE

REPORTING LEVEL, 3-SIGMA

2-SIGMA ERROR

FIELD MEASUREMENT OR

CONSTITUENT CONCENTRATION

CONSTITUENT CONCETRATION, IN

MILLIGRAMS PER LITER

TRITIUM AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

Figure 13. Water-quality data for well USGS 43, 1990-2003, with corresponding data for October-November 2003, Idaho 

National Laboratory, Idaho.

32  Well-Purging Effects on Water-Quality Results, Eastern Snake River Plain Aquifer, Idaho National Laboratory, Idaho
ID9HZ02_fig14a-e

A.

B.

C.

D.

E.

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

0

5.0

10.0

15.0

20.0

25.0

30.0

0

5.0

10.0

15.0

20.0

25.0

30.0

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

-600

-400

-200

0

200

400

600

800

1,000

1,200

-6.0

-4.0

-2.0

0.0

2.0

4.0

6.0

8.0

10.0

12.0

-200

-150

-100

-50

50

100

150

CESIUM-137 AND 2-SIGMA ERROR, IN

PICOCURIES PER LITER

0

SULFATE, IN MILLIGRAMS PER LITER

TEMPERATURE, IN DEGREES CELCIUS

pH, UNITS

SPECIFIC CONDUCTANCE/100,

 MICROSIEMENS PER CENTIMETERS

EXPLANATION

CHLORIDE

SODIUM

NITRATE

REPORTING LEVEL, 3-SIGMA

2-SIGMA ERROR

FIELD MEASUREMENT OR

CONSTITUENT CONCENTRATION

CONSTITUENT CONCETRATION, 

IN MILLIGRAMS PER LITER

TRITIUM AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

STRONTIUM-90 AND 2-SIGMA ERROR, IN

PICOCURIES PER LITER

Figure 14. Water-quality data for well USGS 44, 1990-2003, with corresponding data for October-November 2003, Idaho 

National Laboratory, Idaho.

Figures  33
ID9HZ02_fig15a-d

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

A.

B.

C.

D.

0

2

4

6

8

10

12

14

-500

0

500

1,000

1,500

2,000

2,500

3,000

-5

0

5

10

15

20

25

TRITIUM AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER STRONTIUM-90 AND 2-SIGMA ERROR, IN PICOCURIES PER LITER

FIELD MEASUREMENT OR

CONSTITUENT CONCENTRATION

CONSTITUENT CONCETRATION, 

IN MILLIGRAMS PER LITER

5

0

10

15

20

25

30

SULFATE

TEMPERATURE, IN DEGREES CELCIUS

pH, UNITS

SPECIFIC CONDUCTANCE/100,

 MICROSIEMENS PER CENTIMETERS

EXPLANATION

CHLORIDE

SODIUM

NITRATE, IN MILLIGRAMS PER LITER

REPORTING LEVEL, 3-SIGMA

2-SIGMA ERROR

Figure 15. Water-quality data for well USGS 45, 1990-2003, with corresponding data for October-November 2003, Idaho 

National Laboratory, Idaho.

34  Well-Purging Effects on Water-Quality Results, Eastern Snake River Plain Aquifer, Idaho National Laboratory, Idaho
ID9HZ02_fig16a-e

A. D.

E.

B.

C.

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

0

5.0

10.0

15.0

20.0

25.0

30.0

0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

-5.0

0.0

5.0

10.0

15.0

20.0

25.0

30.0

-200

-150

-100

-50

0

50

100

150

200

FIELD MEASUREMENT OR

CONSTITUENT CONCENTRATION

CONSTITUENT CONCETRATION, 

IN MILLIGRAMS PER LITER

TRITIUM AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

STRONTIUM-90 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

CESIUM-137 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

SULFATE, IN MILLIGRAMS PER LITER

TEMPERATURE, IN DEGREES CELCIUS

pH, UNITS

SPECIFIC CONDUCTANCE/100,

 MICROSIEMENS PER CENTIMETER

EXPLANATION

CHLORIDE

SODIUM

NITRATE

REPORTING LEVEL, 3-SIGMA

2-SIGMA ERROR

Figure 16. Water-quality data for well USGS 46, 1990-2003, with corresponding data for October-November 2003, Idaho 

National Laboratory, Idaho.

Figures  35
ID9HZ02_fig17a-h

0

5

10

15

20

25

30

35

40

45

50

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

A. E.

F.

G.

H.

B.

C.

D.

0

5

10

15

20

25

30

35

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

16,000

-150

-100

-50

50

100

150

0

0

10

20

30

40

50

60

70

80

90

-0.15

-0.10

-0.05

0.00

0.05

0.10

0.15

0.20

0.25

-0.08

-0.06

-0.04

-0.02

0.00

0.02

0.04

0.06

0.08

-0.15

-0.10

-0.05

0.00

0.05

0.10

0.15

FIELD MEASUREMENT OR

CONSTITUENT CONCENTRATION

CONSTITUENT CONCETRATION, 

IN MILLIGRAMS PER LITER

CESIUM-137 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

PLUTONIUM-238 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

SULFATE, IN MILLIGRAMS PER LITER

TEMPERATURE, IN DEGREES CELCIUS

pH, UNITS

SPECIFIC CONDUCTANCE/100,

 MICROSIEMENS PER CENTIMETERS

EXPLANATION

CHLORIDE

SODIUM

NITRATE

REPORTING LEVEL, 3-SIGMA

2-SIGMA ERROR

TRITIUM AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

STRONTIUM-90 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

PLUTONIUM-239, -240 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

AMERICIUM-241 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

Figure 17. Water-quality data for well USGS 47, 1990-2003, with corresponding data for October-November 2003, Idaho 

National Laboratory, Idaho.

36  Well-Purging Effects on Water-Quality Results, Eastern Snake River Plain Aquifer, Idaho National Laboratory, Idaho
ID9HZ02_fig18a-d

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

A.

B.

C.

D.

0

5

10

15

20

25

30

35

40

45

0

5

10

15

20

25

30

35

0

2,000

4,000

6,000

8,000

10,000

12,000

0

5

10

15

20

25

30

35

40

SULFATE

TEMPERATURE, IN DEGREES CELCIUS

pH, UNITS

SPECIFIC CONDUCTANCE/100,

 MICROSIEMENS PER CENTIMETER

EXPLANATION

CHLORIDE, IN MILLIGRAMS PER LITER

SODIUM

NITRATE

REPORTING LEVEL, 3-SIGMA

2-SIGMA ERROR

FIELD MEASUREMENT OR

CONSTITUENT CONCENTRATION

CONSTITUENT CONCETRATION, 

IN MILLIGRAMS PER LITER

TRITIUM AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER STRONTIUM-90 AND 2-SIGMA ERROR, IN PICOCURIES PER LITER

Figure 18. Water-quality data for well USGS 48, 1990-2003, with corresponding data for October-November 2003, Idaho 

National Laboratory, Idaho.

Figures  37
ID9HZ02_fig19a-e

A. D.

E.

B.

C.

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

0

10.0

20.0

30.0

40.0

50.0

0

20,000

40,000

60,000

80,000

100,000

120,000

0

50

100

150

200

250

300

350

-150

-100

-50

0

50

100

150

200

FIELD MEASUREMENT OR

CONSTITUENT CONCENTRATION

CONSTITUENT CONCETRATION, 

IN MILLIGRAMS PER LITER

TRITIUM AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

STRONTIUM-90 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

CESIUM-137 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

0

10

20

30

40

50

60

70

80

90

100

SULFATE, IN MILLIGRAMS PER LITER

TEMPERATURE, IN DEGREES CELCIUS

pH, UNITS

SPECIFIC CONDUCTANCE/100,

 MICROSIEMENS PER CENTIMETER

EXPLANATION

CHLORIDE

SODIUM

NITRATE

REPORTING LEVEL, 3-SIGMA

2-SIGMA ERROR

Figure 19. Water-quality data for well USGS 50 (perched well), 1990-2003, with corresponding data for 

October-November 2003, Idaho National Laboratory, Idaho.

38  Well-Purging Effects on Water-Quality Results, Eastern Snake River Plain Aquifer, Idaho National Laboratory, Idaho
ID9HZ02_fig20a-d

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

A.

B.

C.

D.

0

10

20

30

40

50

60

0

20

40

60

80

100

120

140

160

180

200

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

-10

-8

-6

-4

-2

0

2

4

6

8

10

SULFATE

TEMPERATURE, IN DEGREES CELCIUS

pH, UNITS

SPECIFIC CONDUCTANCE/100,

 MICROSIEMENS PER CENTIMETER

EXPLANATION

CHLORIDE

SODIUM, IN MILLIGRAMS PER LITER

NITRATE

REPORTING LEVEL, 3-SIGMA

2-SIGMA ERROR

FIELD MEASUREMENT OR

CONSTITUENT CONCENTRATION

CONSTITUENT CONCETRATION, 

IN MILLIGRAMS PER LITER

TRITIUM AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

STRONTIUM-90 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

Figure 20. Water-quality data for well USGS 51, 1990-2003, with corresponding data for October-November 2003, Idaho 

National Laboratory, Idaho.

Figures  39
ID9HZ02_fig21a-d

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

B.

A. C.

D.

0

5

10

15

20

25

30

0

5

10

15

20

25

30

35

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

9,000

0

2

4

6

8

10

12

14

16

18

20

SULFATE

TEMPERATURE, IN DEGREES CELCIUS

pH, UNITS

SPECIFIC CONDUCTANCE/100,

 MICROSIEMENS PER CENTIMETER

EXPLANATION

CHLORIDE, IN MILLIGRAMS PER LITER

SODIUM

NITRATE

REPORTING LEVEL, 3-SIGMA

2-SIGMA ERROR

FIELD MEASUREMENT OR

CONSTITUENT CONCENTRATION

CONSTITUENT CONCETRATION, 

IN MILLIGRAMS PER LITER

TRITIUM AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

STRONTIUM-90 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

Figure 21. Water-quality data for well USGS 52, 1990-2003, with corresponding data for October-November 2003, Idaho 

National Laboratory, Idaho.

40 Well-Purging Effects on Water-Quality Results, Eastern Snake River Plain Aquifer, Idaho National Laboratory, Idaho
ID9HZ02_fig22a-e

0

10.0

20.0

30.0

40.0

A. D.

B.

C.

E.

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

0

50

100

150

200

250

0

5,000

10,000

15,000

20,000

25,000

30,000

0.0

10.0

20.0

30.0

40.0

50.0

60.0

-150

-100

-50

0

50

100

150

SULFATE, IN MILLIGRAMS PER LITER

TEMPERATURE, IN DEGREES CELCIUS

pH, UNITS

SPECIFIC CONDUCTANCE/100,

 MICROSIEMENS PER CENTIMETER

EXPLANATION

CHLORIDE

SODIUM

NITRATE

REPORTING LEVEL, 3-SIGMA

2-SIGMA ERROR

FIELD MEASUREMENT OR

CONSTITUENT CONCENTRATION

CONSTITUENT CONCETRATION, 

IN MILLIGRAMS PER LITER

TRITIUM AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

CESIUM-137 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

STRONTIUM-90 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

Figure 22. Water-quality data for well USGS 57, 1990-2003, with corresponding data for October-November 2003, Idaho 

National Laboratory, Idaho.

Figures  41
ID9HZ02_fig23a-h

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

A.

B.

E.

F.

G.

H.

C.

D.

0

5

10

15

20

25

30

35

0

20

40

60

80

100

120

140

160

180

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

45,000

50,000

0

2

4

6

8

-8

-6

-4

-2

10

-200

-150

-100

-50

0

50

100

150

-0.06

-0.04

-0.02

0.00

0.02

0.04

0.06

0.08

0.10

-0.08

-0.06

-0.04

-0.02

0.00

0.02

0.04

0.06

0.08

0.10

-0.15

-0.10

-0.05

0.00

0.05

0.10

0.15

0.20

PLUTONIUM-239, -240 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

AMERICIUM-241 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

CESIUM-137 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

PLUTONIUM-238 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

FIELD MEASUREMENT OR

CONSTITUENT CONCENTRATION

CONSTITUENT CONCETRATION, 

IN MILLIGRAMS PER LITER

TRITIUM AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

STRONTIUM-90 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

SULFATE, IN MILLIGRAMS PER LITER

TEMPERATURE, IN DEGREES CELCIUS

pH, UNITS

SPECIFIC CONDUCTANCE/100,

 MICROSIEMENS PER CENTIMETER

EXPLANATION

CHLORIDE

SODIUM

NITRATE

REPORTING LEVEL, 3-SIGMA

2-SIGMA ERROR

Figure 23. Water-quality data for well USGS 77, 1990-2003, with corresponding data for October-November 2003, Idaho 

National Laboratory, Idaho.

42  Well-Purging Effects on Water-Quality Results, Eastern Snake River Plain Aquifer, Idaho National Laboratory, Idaho
ID9HZ02_fig23i-l

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

1995 1996 1997 1998 1999 2000 2001 2002 2003

I. K.

L.

J.

-2

-1

0

1

2

3

4

5

GROSS ALPHA RADIOACTIVITY AND

2-SIGMA ERROR,

IN PICOCURIES PER LITER

0

2

4

6

8

10

12

14

16

18

20

GROSS BETA RADIOACTIVITY AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

0

2

4

6

8

10

12

14

16

18

CONSTITUENT CONCENTRATION

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

CONSTITUENT CONCETRATION, 

IN MICROGRAMS PER LITER

TOTAL DISSOLVED CHROMIUM,

 IN MICROGRAMS PER LITER

FLUORIDE, IN MILLIGRAMS PER LITER

TOTAL ORGANIC CARBON,

IN MILLIGRAMS PER LITER

EXPLANATION

1,1,1-TRICHLOROETHANE

1,1-DICHLOROETHENE

REPORTING LEVEL, 3-SIGMA

2-SIGMA ERROR

Figure 23. Continued.

Figures  43
ID9HZ02_fig24a-d

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

B.

A. C.

D.

0

5

10

15

20

25

30

0

5

10

15

20

25

-1,000

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

-10.0

-5.0

0.0

5.0

10.0

15.0

SULFATE

TEMPERATURE, IN DEGREES CELCIUS

pH, UNITS

SPECIFIC CONDUCTANCE/100,

 MICROSIEMENS PER CENTIMETER

EXPLANATION

CHLORIDE, IN MILLIGRAMS PER LITER

SODIUM

NITRATE

REPORTING LEVEL, 3-SIGMA

2-SIGMA ERROR

FIELD MEASUREMENT OR

CONSTITUENT CONCENTRATION

CONSTITUENT CONCETRATION, 

IN MILLIGRAMS PER LITER

TRITIUM AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

STRONTIUM-90 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

Figure 24. Water-quality data for well USGS 82, 1990-2003, with corresponding data for October-November 2003, Idaho 

National Laboratory, Idaho.

44  Well-Purging Effects on Water-Quality Results, Eastern Snake River Plain Aquifer, Idaho National Laboratory, Idaho
ID9HZ02_fig25a-d

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

A.

B.

C.

D.

0

2

4

6

8

10

12

14

16

0

10

20

30

40

50

60

70

80

0

5,000

10,000

15,000

20,000

25,000

30,000

TRITIUM AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

STRONTIUM-90 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

-6.0

-4.0

-2.0

0.0

2.0

4.0

6.0

8.0

10.0

SULFATE

TEMPERATURE, IN DEGREES CELCIUS

pH, UNITS

SPECIFIC CONDUCTANCE/100,

 MICROSIEMENS PER CENTIMETER

EXPLANATION

CHLORIDE

SODIUM

NITRATE, IN MILLIGRAMS PER LITER

REPORTING LEVEL, 3-SIGMA

2-SIGMA ERROR

FIELD MEASUREMENT OR

CONSTITUENT CONCENTRATION

CONSTITUENT CONCETRATION, 

IN MILLIGRAMS PER LITER

Figure 25. Water-quality data for well USGS 85, 1990-2003, with corresponding data for October-November 2003, Idaho 

National Laboratory, Idaho.

Figures  45
ID9HZ02_fig26a-d

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

0

2

4

6

8

10

12

14

16

0

20

40

60

80

100

120

140

160

180

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

-8.0

-6.0

-4.0

-2.0

0.0

2.0

4.0

6.0

8.0

A.

B.

C

D.

SULFATE

TEMPERATURE, IN DEGREES CELCIUS

pH, UNITS

SPECIFIC CONDUCTANCE/100,

 MICROSIEMENS PER CENTIMETER

EXPLANATION

CHLORIDE

SODIUM

NITRATE, IN MILLIGRAMS PER LITER

REPORTING LEVEL, 3-SIGMA

2-SIGMA ERROR

FIELD MEASUREMENT OR

CONSTITUENT CONCENTRATION

CONSTITUENT CONCETRATION, 

IN MILLIGRAMS PER LITER

TRITIUM AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

STRONTIUM-90 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

Figure 26. Water-quality data for well USGS 111, 1990-2003, with corresponding data for October-November 2003, Idaho 

National Laboratory, Idaho.

46  Well-Purging Effects on Water-Quality Results, Eastern Snake River Plain Aquifer, Idaho National Laboratory, Idaho
ID9HZ02_fig27a-d

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

0

2

4

6

8

10

12

14

16

18

0

50

100

150

200

250

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

0

5

10

15

20

25

30

35

40

45

50

A.

B.

C.

D.

SULFATE

TEMPERATURE, IN DEGREES CELCIUS

pH, UNITS

SPECIFIC CONDUCTANCE/100,

 MICROSIEMENS PER CENTIMETER

EXPLANATION

CHLORIDE

SODIUM

NITRATE, IN MILLIGRAMS PER LITER

REPORTING LEVEL, 3-SIGMA

2-SIGMA ERROR

FIELD MEASUREMENT OR

CONSTITUENT CONCENTRATION

CONSTITUENT CONCETRATION, 

IN MILLIGRAMS PER LITER

TRITIUM AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

STRONTIUM-90 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

Figure 27. Water-quality data for well USGS 112, 1990-2003, with corresponding data for October-November 2003, Idaho 

National Laboratory, Idaho.

Figures  47
ID9HZ02_fig28a-e

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

A.

E.

B.

C.

D.

0

5

10

15

20

25

30

35

40

45

50

0

50

100

150

200

250

300

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

45,000

0

5

10

15

20

25

30

35

-200

-150

-100

-50

0

50

100

150

CESIUM-137 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

SULFATE, IN MILLIGRAMS PER LITER

TEMPERATURE, IN DEGREES CELCIUS

pH, UNITS

SPECIFIC CONDUCTANCE/100,

 MICROSIEMENS PER CENTIMETER

EXPLANATION

CHLORIDE

SODIUM

NITRATE

REPORTING LEVEL, 3-SIGMA

2-SIGMA ERROR

FIELD MEASUREMENT OR

CONSTITUENT CONCENTRATION

CONSTITUENT CONCETRATION, 

IN MILLIGRAMS PER LITER

TRITIUM AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

STRONTIUM-90 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

Figure 28. Water-quality data for well USGS 113, 1990-2003, with corresponding data for October-November 2003, 

Idaho National Laboratory, Idaho.

48  Well-Purging Effects on Water-Quality Results, Eastern Snake River Plain Aquifer, Idaho National Laboratory, Idaho
ID9HZ02_fig29a-d

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

B.

A.

0

2

4

6

8

10

12

14

16

0

20

40

60

80

100

120

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

-8.0

-6.0

-4.0

-2.0

0.0

2.0

4.0

6.0

8.0

10.0

D.

C.

SULFATE

TEMPERATURE, IN DEGREES CELCIUS

pH, UNITS

SPECIFIC CONDUCTANCE/100,

 MICROSIEMENS PER CENTIMETER

EXPLANATION

CHLORIDE

SODIUM

NITRATE, IN MILLIGRAMS PER LITER

REPORTING LEVEL, 3-SIGMA

2-SIGMA ERROR

FIELD MEASUREMENT OR

CONSTITUENT CONCENTRATION

CONSTITUENT CONCETRATION, 

IN MILLIGRAMS PER LITER

TRITIUM AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

STRONTIUM-90 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

Figure 29. Water-quality data for well USGS 114, 1990-2003, with corresponding data for October-November 2003, Idaho 

National Laboratory, Idaho.

Figures   49
ID9HZ02_fig30a-d

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

A.

B.

C.

D.

0

2

4

6

8

10

12

14

16

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

-10.0

-8.0

-6.0

-4.0

-2.0

0.0

2.0

4.0

6.0

8.0

10.0

0

10

20

30

40

50

60

SULFATE

TEMPERATURE, IN DEGREES CELCIUS

pH, UNITS

SPECIFIC CONDUCTANCE/100,

 MICROSIEMENS PER CENTIMETER

EXPLANATION

CHLORIDE

SODIUM

NITRATE, IN MILLIGRAMS PER LITER

REPORTING LEVEL, 3-SIGMA

2-SIGMA ERROR

FIELD MEASUREMENT OR

CONSTITUENT CONCENTRATION

CONSTITUENT CONCETRATION, 

IN MILLIGRAMS PER LITER

TRITIUM AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

STRONTIUM-90 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

Figure 30. Water-quality data for well USGS 115, 1990-2003, with corresponding data for October-November 2003, Idaho 

National Laboratory, Idaho.

50 Well-Purging Effects on Water-Quality Results, Eastern Snake River Plain Aquifer, Idaho National Laboratory, Idaho
ID9HZ02_fig31a-d

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

0

5

10

15

20

25

30

35

40

0

20

40

60

80

100

120

140

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

16,000

18,000

A.

B.

C.

D.

-10

-8

-6

-4

-2

0

2

4

6

8

10

FIELD MEASUREMENT OR

CONSTITUENT CONCENTRATION

CONSTITUENT CONCETRATION, 

IN MILLIGRAMS PER LITER

TRITIUM AND 2-SIGMA ERROR,

IN PICORCURIES PER LITER

STRONTIUM-90 AND 2-SIGMA ERROR,

IN PICORCURIES PER LITER

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

SULFATE, IN MILLIGRAMS PER LITER

TEMPERATURE, IN DEGREES CELCIUS

pH, UNITS

SPECIFIC CONDUCTANCE/100,

 MICROSIEMENS PER CENTIMETERS

EXPLANATION

CHLORIDE

SODIUM

NITRATE

REPORTING LEVEL, 3-SIGMA

2-SIGMA ERROR

Figure 31. Water-quality data for well USGS 116, 1990-2003, with corresponding data for October-November 2003, Idaho 

National Laboratory, Idaho.

Figures   51
ID9HZ02_fig32a-d

A.

B.

C.

D.

1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

0

0

2

4

6

8

10

12

14

16

20

40

60

80

100

120

140

160

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

0

10

20

30

40

50

60

70

TRITIUM AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

STRONTIUM-90 AND 2-SIGMA ERROR,

IN PICOCURIES PER LITER

FIELD MEASUREMENT OR

CONSTITUENT CONCENTRATION

CONSTITUENT CONCETRATION, 

IN MILLIGRAMS PER LITER

SULFATE

TEMPERATURE, IN DEGREES CELCIUS

pH, UNITS

SPECIFIC CONDUCTANCE/100,

 MICROSIEMENS PER CENTIMETER

EXPLANATION

CHLORIDE

SODIUM

NITRATE, IN MILLIGRAMS PER LITER

REPORTING LEVEL, 3-SIGMA

2-SIGMA ERROR

Figure 32. Water-quality data for well USGS 123, 1990-2003, with corresponding data for October-November 2003, Idaho 

National Laboratory, Idaho.

52  Well-Purging Effects on Water-Quality Results, Eastern Snake River Plain Aquifer, Idaho National Laboratory, Idaho
Manuscript approved for publication, September 14, 2006

Prepared by the USGS Publishing Network, 

Publishing Service Center, Tacoma, Washington

Bill Gibbs 

Debra Grillo

Bobbie Jo Richey

For more information concerning the research in this report, contact the 

Director, Idaho Water Science Center 

U.S. Geological Survey, 230 Collins Road

Boise, Idaho 83702

http://id.water.usgs.gov/
SIR 2006–5232 Knobel Evaluation of Well-Purging Effects on Water-Quality Results for Samples Collected from the 

Eastern Snake River Plain Aquifer Underlying the Idaho National Laboratory, Idaho