SFUND RECORDS CTR 2073226 · 2016. 12. 20. · SFUND RECORDS CTR 2073226 Reprinted from UNCERTAINTY IN THE GEOLOGIC ENVIRONMENT: From Theory to Practice Proceedings of Uncertainty

SFUND RECORDS CTR

2073226

Reprinted from UNCERTAINTY IN THE GEOLOGICENVIRONMENT: From Theory to Practice

Proceedings of Uncertainty '96Geotechnical Engineering Division/ASCE

HeldJufy 31 -August3, 1996, Madison, Wis.

GROUND WATER VARIABILITY AT SANITARY LANDFILLSCAUSES AND SOLUTIONS

John Oneacre1

Debbie Figueras2

Abstract

New Federal Solid Waste Regulations, Part 258, Subpart E of theResource Conservation and Recovery Act [RCRA], require substantialground water monitoring systems at municipal solid waste landfills. Poorunderstanding of the site hydrogeological conditions can lead toerroneous and non-representative ground water data. Variability ofground water data can be due to well location, well design, drillingmethod, well development, and sample collection and analysis. Thispaper discusses steps owners can take to mitigate variability.

Introduction

New Federal Solid Waste Regulations, Part 258, Subpart E of theResource Conservation and Recovery Act [RCRA], require substantialground water monitoring at municipal solid waste landfills. Owners andoperators of landfills must adequately define the site geology andhydrogeology to ensure proper monitoring. Essential elements ofdefining the site include stratigraphy, lithology, hydraulic conductivities,porosities, ground water flow direction and velocity vectors. In addition,the owner/operator must develop a sampling and analysis plan andstatistically analyze the geochemical data. Oneacre [1992, 1993]discusses these regulations in more detail for the owner subject to theserequirements.

1 Director, Ground Water Services Division, BFI, 757 N. Eldridge,Houston, Texas 77079.

2 Data Analyst, Ground Water Services Division, BFI, 757 N. Eldridge,Houston, Texas 77079.

965

966 UNCERTAINTY IN GEOLOGIC ENVIRONMENT

This paper discusses several causes of ground water variabilityand uncertainty at sanitary landfills observed routinely by the authorsthat include well location, well design, drilling method, well development,and sample collection and analysis. Case studies illustrate both theproblems associated with inadequate site characterization and practicalsolutions.

Inadequate Site Characterization: Case Study 1

Figure 1 shows a plan view of a 200-acre site that received bothmunicipal solid waste [MSW] and hazardous waste in a glaciated areadescribed as "ground water poor". The owner installed 150 monitoringwells and concluded that the site had a simple geology consisting ofPleistocene till with thin outwash deposits overlying Ordovicianlimestones and shales. Despite the number of wells, the owner failed toidentify the most significant geological feature beneath the site, a buriedchannel sand of clean sand and gravel below the outwash deposits.Figure 2 shows a simple cross-section of the site geology with therelationship of the channel deposit to the outwash deposits.

Consultants mistakenly interpreted the channel sand to beoutwash deposits and compiled a potentiometric map with data fromboth the outwash and channel sand and inferred radial ground waterflow [Figure 1 ]. Compounding this situation, high pH and chloride valuesin some wells prompted both the State and the USEPA to issueadministrative orders against the owner.

In retrospect, key geological data were overlooked. The channelsand occurs below the outwash deposits, and is a clean sand and graveldeposit from a high energy environment, whereas the outwash depositsare dirty sandy silts from a much lower energy environment. Hydraulicconductivity of the channel sand is about 0.1 cm/sec compared to 1 x10'6 cm/sec for the outwash deposits. The channel sand is a confinedaquifer; the outwash deposits are unconfined to semi-confineddemonstrating hydraulic separation.

Cell dewatering caused a large drawdown in the channel sand andjust one well in the depressured channel sand northwest of the site wasresponsible for the radial flow interpretation. Figure 1 shows the correctflow pattern in the outwash. Ground water in the glacial deposits is acalcium-magnesium sulfate type water and distinctly different from theconnate bedrock ground water which is a sodium chloride type; elevatedpH values [Figure 3] were due solely to grout contamination from poorwell construction.

GROUND WATER VARIABILITY 967

FIGURE 1

INCORRECT POTENTIOMETRIC INTERPRETATIONFOR OUTWASH DEPOSITS

Channel Sand Well

""^- £r/-^ i«. _ \ ^v .71; . ̂ J

\r\ ?»-t.._ 'x .̂ ': / y*

?^v / ?Sv£ •/">"j ̂ 4 7 .̂..r / vV'V:'-/ ./.•••••i.Y -; Dewatered/ • \£*K

PropertyBoundary

•: Channel/

SanitaryA sk

\ _.->-?~: Waste Limits

7\

CORRECT POTENTIOMETRIC INTERPRETATIONFOR OUTWASH DEPOSITS

Waste

PropertyBoundary

Ground WaterFlow DirectionLimits OfChannel SandPotentiometricSurface Elevation


FIGURE 2

GEOLOGIC CROSS SECTION A-A'CASE STUDY 1

Till

A1

Looking NorthwestNot To Scale

Till

Sand OutwashDeposits

• Channel Deposit

•Otdovician Bedrock

FIGURE 3

ERRONEOUS PH INTERPRETATIONDUE TO IMPROPER WELL CONSTRUCTION

/*•-.

Note: Actual pH Values Are Approximately 7.


Improper Well Location

Too often, with the misguided intention to save money, ownersand consultants install wells in exploratory borings without regard for theoverall picture of the site hydrogeology resulting in dry wells, wellsscreened across multiple hydrostratigraphic intervals, and confusingvertical gradient interpretations. Merely placing wells along specifiedspacings will not guarantee satisfactory coverage for monitoring sincethe most important ground water zones may be missed. Using theprevious case study as an example, placing wells on the corners of thecells did little to identify the most prominent aquifer on site. Ironically,had the owner properly characterized the site, the number of monitoringwells could have been greatly reduced.

Only after thoroughly investigating the site specific geology andhydrogeology, should the owner install monitoring wells. Although thiswill usually require a two-tier field program, such an approach is the besttechnically, and is the most cost-effective.

Well Design

A typical monitor well design is a 10-slot [0.010 inch] screen with20-40 silica sand which may not be appropriate. For coarse-graineddeposits, placing too fine of a sand pack and well slot may restrict flowand influence hydraulic conductivity determinations which will bias flowvelocity calculations. Also, fine sand will have more difficulty settlingout of the borehole fluid. Conversely, using too coarse a sand pack willcreate turbidity and analyses problems. By conducting a two-tier fieldprogram, the owner can select the proper screen length and requestgrain size analyses that will then determine the appropriate slot size andsand/gravel pack.

Well Materials

Researchers have written many technical papers regarding bias ofwell materials on ground water samples. For a thorough review of thistopic, see Parker [1994] and Llopis [1991]. Some of the materialresearch has been misapplied. For example, Barcelona et al., [1983]reported that PVC leached dimethyltin at 35 ug/L. However, the originalpaper [Boettner, et al., 1981] noted that only glued PVC pipe sectionsleached low level dimethyltin as well as tetrahydrofuran, methyl ethylketone and cyclohexanone at levels as high as 10 mg/l.


The glue acted as a catalyst for the release of the dimethyltin. USEPAused Barcelona's report and required owners to use only 316 stainlesssteel or polytetrafluoroethylene [PTFE] [USEPA, 1986], which wasproblematic for owners.

Case Study 2

EPA's material requirement reversed the agency's previousfavorable opinion of PVC [USEPA, 1980 and Everett, 1980] and resultedin a lawsuit [BNA, 1990] when the USEPA ordered a major solid wastecompany to install stainless steel wells at a landfill in a highly corrosiveenvironment of the pyritic Magothy Formation in New Jersey. Groundwater is naturally acidic, and Figure 4 shows the trend of pH andchromium over time in one well. Within a few months of installation thepH dropped from 5.5 to a value of 2.7 due to depressed ground waterlevels which exposed pyrite to oxidation. Within 12 months ofinstallation, analytical results showed very high values for chromium,nickel, cadmium, iron,and copper, all corrosion constituents of stainlesssteel [Sedriks, et al., 1979]. Although passive stainless steel is quiteresistant to corrosion due to an oxygen layer on the surface, stainlessbecomes very active and susceptible to corrosion if the oxygen layer isdepleted by scratches or microbiological influenced corrosion [Pope, etal., 1984]. Most corrosion will occur at phase boundaries and heataffected zones. A downhole video survey identified severe corrosion atthe top of the well screen which coincided with the ground water tableand maximum weld points. Figure 5 shows the corroded screen afterremoval from the ground. PVC wells in the same formation have notexperienced any performance or sample bias problems.

Drilling Methods

The authors' preference of drilling methods includes percussion,cable tool, air rotary, reverse circulation and mud rotary. Using theproper equipment to drill a 50 foot well, the owner pays about 3 percentof the total well cost for development. Development costs for augerwells add 20 percent to the well cost, a 600 percent increase overnormal development cost; if an augered well cannot be successfullydeveloped, the well replacement cost doubles the owner's cost.

The most common drilling method used for installation ofmonitoring wells [USEPA, 1992] is also the most inappropriate method,the hollow-stem auger. USEPA does not recommend its use forinstallation of ground water monitoring wells [USEPA, 1992],Consultants use augering for installation since it is relatively fast andinexpensive.

GROUND WATER VARIABILITY

FIGURE 4CHROMIUM & pH RELATIONSHIP

Test Well B-13R

971

4000 T

05-87 07-87 10-87 01-88 03-89 03-89 02-90 03-91Sample Date

Chromium, ug/1 — ••— pH.su

FIGURE 5

CORRODED WELL SCREEN FROM WELL B-13R


However, as Aller [1989] points out, the hollow-stem auger hasproblems with cross-contamination, sand heaving, and formation damagedue to smearing of silts and clays.

In the Gulf Coast area, auger wells, after days of development,typically have high turbidity and provide minimal yield. Likewise, a testwell installed by the Rotosonic vibratory method would not produce anywater from the Beaumont Clay due to the clay flowing and sealing offthe water bearing zone. Conversely, wells installed with a percussionhammer rig in the same formation developed low turbidity values [1NTU] within 3 hours with sustained yields between 1 and 5 gallons perminute. Although the drilling rate per foot is more expensive with thepercussion rig, this cost was more than offset by the development costsavings. The end result was a monitoring well that produced both highquality ground water and representative yield.

The impact of the drilling method on the calculated hydraulicconductivity of the formation is an important, often overlooked criterion.Cable tool wells adjacent to auger wells in Illinois produced an order ofmagnitude higher hydraulic conductivity which increased the calculatedflow velocity by an order of magnitude. Water well drillers havedemonstrated the utility and cost-effectiveness of the cable tool [Edberg,et al., 1994].

Well Installation

Another simple but important criterion for proper well installationincludes adequate annular space between drift rods and well screen forsand/gravel pack placement. Less than a 3 inch annular space increasesthe likelihood of sand bridging, screen locking, or bentonite bridging.Pre-development surging will help settle the sand/gravel pack prior toplacement of the bentonite seal. Figure 6 shows the gap between silicasand and bentonite without surging 45 minutes after the seal was placedin ordinary tap water. The authors have noted as much as 3 feet ofsand settlement during the pre-development process. Using a side-discharge tremie pipe for grout placement will dissipate all the pumpenergy to the side walls of the borehole instead of the bentonite seal andavoid grout contamination.

Well Development

Subtitle D requires total metals analyses which necessitatescomplete well development. The authors use a 5 NTU criteria fordevelopment and also require surging and overpumping incrementallythroughout the screened interval to totally develop the well.


FIGURE 6

SETTLEMENT OF SAND AFTER PLACEMENT OF BENTONITE SEAL


Despite some experts concerns that low turbidity cannot beachieved in fine-grained formations [Nielsen, 1993], the authorsconsistently achieve low turbidity in fine-grained formations such asglacial till, loess, and coastal silts and clays. Although research [Puts, etal., 1992; Backhus, et al., 1993; Barcelona, et al., 1994] has shownthat low pumping rates produce low turbidities, merely recommendinglow flow masks poor well construction and ultimately costs the ownerin the form of biased data.

Researchers [Puls and Powell, 1992; Powell and Puls, 1993]conducted passive, low flow sampling [0.2 L/min] as a means tomaintain low turbidity in sediments with hydraulic conductivity values ofabout 15 m/day [2x10'2 cm/sec], and despite the good hydraulicconductivity, bladder pumps still had difficulty achieving low turbidities.

Case Studies 3 and 4

By contrast, Case Study 3 presents wells in the Beaumont Clayformation with hydraulic conductivity values of 10"3 to 10"a cm/sec, 1 to4 orders of magnitude less than the Puls and Powell site. Table 1demonstrates that with proper design, construction, and development,fine grained sediments can produce high quality water at substantiallyhigher flow rates without turbidity problems. To determine whenturbidity begins to bias total metals analyses, the authors compiled20,000 metal analyses from 1994 [Figure 7]. About 10 percent of thetotal metals analyses with less than 25 NTUs showed quantified metals,primarily barium. A large 36 percent increase occurs between 25 and 50NTUs suggesting that bias due to solids becomes a major concern above25 NTUs. Information from 1,500 well analyses from the fourth quarterof 1994 shows that 75 percent of the authors' samples had less than 25NTUs [Figure 8]. Turbidity values above this value represent wells withbailers rather than dedicated pumps.

In Case Study 4, Figure 9 displays turbidity and heavy metalsvalues from a landfill in the eastern United States. This formationtypically has less than 20 percent material passing the No. 200 sieve butstill caused significant turbidity and metals problems due to inadequatedevelopment. Redevelopment of the wells in April, 1994 reduced theturbidity to levels below 5 NTUs and provided representative groundwater samples. Heavy metals such as chromium dropped to non-detectlevels after proper development. Figure 10 shows the visualimprovement of water clarity after proper redevelopment which requiredless than five hours to achieve.


TABLE 1

WELL DEVELOPMENT INFORMATION IN THE BEAUMONT CLAY

W.B No.

1A

1UB

1LB

2A

2UB

2LB

3A

3UB

3LB

4UB

4LB

SUB

5LB

BUB

6LB

7UB

7LB

8LB

SUB

9LB

10UB

10LB

*Ptt*!ngNo. 200 SUv.

13.1

so.e

32.3

38.0

93.0

91.0

42.1

54.2

88.9

94.5

35.0

34.0

8S.O

12.9

42.4

15.8

NA'

21.4

79.8

24.2

16.3

41.0

K(cm/«)

4.0E-4

2.8E-3

NA-

1.07E-4

4.82E-4

1.11E-4

2.00E-4

3.67E-4

1.23E-4

1.30E-4

1.04E-4

3.02E-4

9.96E-4

7.45E-4

5.92E-5

S.64E-4

3.44E-6

9.01E-4

4.79E-5

8.08E-4

2.73E-4

2.08E-5

PUfQ^

Rat* (0PM)

0.5.

2.5

0.75

0.5

3.0

0.75

0.5

2.8

0.75

1.0

0.7

0.7

0.4

2.5

1.O

1.S

0.3

2.5

1.0

2.5

2.5

0.4

D«v«topm«ntTim*

(hour*)

4.0

5.0

7.5

3.5

3.0

6.0

1.0

5.0

8.5

3.5

3.5

4.0

18.0

3.0

9.O

7.5

3.5

3.5

6.0

7.0

2.5

8.5

FindTurbidity

INTO)

4.57

2.74

4.56

2.28

1.23

3.71

3.63

1.32

2.42

1.96

4.28

1.33

4.85

4.10

2.03

4.71

4.69

2.61

3.51

1.44

3.88

3.71

NA - Not Analyzed


60%-r-

40%-<oQtnffl"53

#20%--

KL-

FIGURE 7

PERCENT METALS DETECTEDBY TURBIDITY RANGE

Percentages BasedTested For All Subtitle D Metals And• Have pH Values Above 6.5

PercentIncrease From_<5 Ntu:

Standard

On Samples That

<5

.11Q94

318%

\-\

5-9 10-24 25-49 50-99 100-499 ' >500Turbidity Range In Ntu

2Q94 3Q94 Il.r4Q94 MM Mean

FIGURE 8

METALS ANALYSIS VS. TURBIDITY RANGESFOR FOURTH QUARTER '94

<5 5-9 10-24 25-49 50-99 100-499' Turbidity Range In NTU

• # Detected I l# Analyzed

>500


8

FIGURE 9PILOT REDEVELOPMENT PROJECT MW-9TOTAL METALS ANALYSES (BA, CR, PB)

9-10-93 9-21-93 10-19-94ouu-

400-

300-

200-

100-

n-

— ^

j1

VS^

iim*-fir — .

k--V,-

4

*- • 1^*~^

^

N

"• — I^~"̂ d• — 1

k^ -v,

199^

^" ~H

993wn

t-95- \A/1Wl

^

\

DATA S"H A B;DATA 5

m A p

s*\

*-3^T"V

^̂ <i

AMFMLE1SAMUMF

-REDS•"WcLt

, ; |

'LEC={PLEI) ....

/ELC

|t=

J

)PEt

=«* —9-2-93 9-14-93 4-27-94 4-12-95

SAMPLE DATE— • — Barium • -» — Chromium —^— Lead

FIGURE 10

VISUAL TURBIDITY BEFORE AND AFTER RE-DEVELOPMENT


Ground Water Sampling

The authors currently use a variety of dedicated pumps includingboth bladder pumps and variable speed centrifugal pumps. Thecentrifugal pump reduces purge time, assists in slug and pump tests andconsistently provides low turbidity values. Bladder pumps are limited intheir ability to quickly purge wells and to provide consistently lowturbidity [Paul and Puls, 1992]. Currently, there is a trend to adopt lowflow purging for reducing labor and water disposal costs [Shanklin, et al.,1995]. However, there still is a lack of agreement from researchregarding appropriate purge rates or volumes. Shanklin [1995] suggeststhat two purge volumes from the discharge tubing and pump may beadequate but acknowledges that further study is needed. Paul and Puls[1992] showed that equilibrium within 10 percent could take as muchas 14 well volumes with a bladder pump versus 3 well volumes with avariable speed submersible pump. Oakley and Korte [1996] suggest thathigh purge volume may be necessary to eliminate effects from metallicscreens.

Puls and Paul [1995] showed that purge volume can influenceorganic concentrations by as much as 50 percent and concluded thatwell purging is still required to ensure sample quality. Gibs andImbrigiotta [1990] showed that field parameters often stabilized beforevolatile organics and that only 50 percent of the volatiles stabilized afterpurging three well volumes. Pearsall and Eckhardt [1987] observed thattrichloroethylene concentrations continued to change after three hoursof pumping even though field parameters stabilized in 30 minutes. Smith[1988] noted that organic compounds do not necessarily reachstabilization at the same purge volume.

Although researchers discuss the apparent need to minimize wellscreen lengths and flow rate to detect contamination [Barcelona, 1985;Puls and Paul, 1995] for the last 10 years, monitor wells at a Californialandfill consistently have shown low to high level volatile organics [5 to3000 ug/L] associated with upgradient sources despite the fact that wellscreen lengths exceed 200 feet; purge rates exceed 100 gal/min; groundwater levels fluctuate seasonally on the order of 50 feet; and flowdirection varies seasonally by 90 degrees. The authors' experiencesuggests that purging several well volumes provides a representativeground water sample.


I

I.t

Dedicated Sampling Devices

Researchers evaluating different sampling devices have concludedthat the centrifugal pump provides representative ground water samples[Gass, etal., 1991; Paul and Puls, 1992; and Yeskis, eta!., 1988]. Pulsand Powell, [1992] cite excessive turbidity as one of the effects ofpumping rate and concur with other researchers [Humenick, et al., 1980;Puls and Barcelona, et al., 1989] who recommend low flow purging of0.2 to 0.3 L/min and sampling at 0.1 L/min. As pointed out previously,proper well design, and development will eliminate high turbidity andallow the owner to purge the well at rates appropriate for the well, be it0.1 L/min or 100 gal/min.

Some scientists have raised concerns of temperature increases tothe ground water sample from electric pumps [Pohlmann and Alduino, etal., 1992; and Paul and Puls, 1992]. Paul and Puls, [1992] didacknowledge, however, that the variable speed pump provided thehighest value for trichloroethylene in their study.

One bladder pump manufacturer states that electric pumps canaffect samples [QED, et al., 1996] and advertises that its pumps do notgenerate heat that could alter samples [QED, et al., 1993]. Paul andPuls, [1992] showed a 1 ° C increase with a bladder pump, but did notgive any explanation for the increase.

The authors recently conducted a temperature study, measuringboth downhole and discharge temperatures during well purging ofbladder and variable speed electric pumps. A YSl 3000 temperatureprobe measured temperature at the top of the pump and Orion Model122 and 230 temperature probes measured the discharge.

At a flow of 0.5 gpm, the electric pump exhibited a dischargetemperature about 0.5° C higher than the bladder pump and 0.7° Chigher temperature at 0.05 gpm. Both pumps displayed the same initialhigh temperature spikes likely due to the heat dissipation from thedischarge tubing [Figure 11]. The authors conclusion is that temperatureis not a significant concern with centrifugal pumps.

Sampling and Analysis

Issues surrounding sampling and analysis are many and complex.Consistency is of great importance and following a detailed sampling andanalysis plan as well as using dedicated sampling devices will eliminatemany field problems. Owners should audit the sampling crew andanalytical laboratory on a regulatory basis.


FIGURE 11

BLADDER PUMP AND REDI-FLO2TEMPERATURE STUDY

TEST WELL MW-3D

26-

25-0 -

§24-

1 "123-

£ -22-

21-

1893 ml/min (0.5 gpm)

-^—^_-*. A A A A A A

. A & «&. /

6 1 I I I I 1 I i I I I I I I I I I I I I10 20 30 40 50 60 75 85 95 105

Time. Minutes

BLADDER PUMP

—«•— Downhole

Surface

REDI-FLO2

— • — Downhole

—A— Surface


Also, have a thorough Quality Assurance/Quality Control [QA/QC] checkof the analytical data. The authors have noted various data errors fromthe most qualified laboratories. Table 2 lists the common problemsassociated with lab data. Owners should insist on very detailed andspecific contract language with the laboratory to avoid any confusionregarding deliverables from the laboratory.

Statistical Analysis

Applying correct statistical methods has been the subject of manypapers [Davis and McNichols, 1994; Gibbons, 1990; Gibbons, 1991].Problems associated with statistics fall into two general categories,spatial and temporal. For interwell comparisons, owners need tomaximize upgradient monitoring points to provide sufficient spatialvariability for parameters routinely detected in ground water.Conversely, for intrawell comparisons, failure to account for temporalvariability will also lead to statistical failures. For example, prior toSubtitle D, landfills did not routinely monitor for barium; however, theauthors' experience is that barium occurs at detectable concentrationsin 75 to 90 percent of ground water analyses. Hem [1985] notes thata likely control of barium concentration is the solubility of barite[BaSO4], which is a fairly common mineral [Sillen and Martell, 1964].Using only a minimal number of background sample points potentiallyplaces the owner at risk of future statistical failures by not accountingfor spatial variability of metals such as barium. The owner should obtaina minimum of eight samples prior to running statistical analyses.

Case Study 5

Figure 12 depicts eight background barium samples from a well inVirginia. As Figure 12 shows, the eight samples covered only a 4 monthperiod rather than eight quarters. Background values showed an upwardtrend which is either the seasonal or long term cyclic occurrence.

Statistical comparisons, based upon the ninth sample and usingthe prediction interval approach, failed. Had the site taken theappropriate time to develop the background data, the well would nothave statistically failed and the site would have saved the cost ofresampling and preparing a report for the regulatory agency.

Summary and Recommendations

Owners of Subtitle D facilities can avoid costly expenditures byimplementing the following recommendations.


TABLE 2

COMMON LABORATORY REPORT ERRORS1 ST QUARTER '95

ERROR TYPE

INCORRECT VALUEINCORRECT VALUE QUALIFIERINCORRECT METHOD DETECTION LIMITINCORRECT CONSTITUENTINCORRECT UNITSMISSING /ADDITIONAL CONSTITUENTSMISPLACED CONSTITUENTS

TOTAL INCORRECT RECORDSTOTAL CORRECT RECORDS

NUMBER OFRECORDS

271513677847

26491036

4743120462

% ERROR

0.020.010.10.6

0.042.10.8

3.896.2

TOTAL NUMBER OF RECORDS = 125210CONSIST OF DATA FROM 20 ANALYTICAL LABORATORIES

FIGURE 12

BARIUM STATISTICAL FAILURETEST WELL MW-6S

01-18-94 05-25-94 04-26-95U.UH-

0.07-

1 'g 0.06-D

'«3CQ

0.05-

n r\A -

< ^r..„.„...,™.

StatiisticafFailu

;;

LX/I,*•V: R^

;

e -

V

jsam

S

/ \"

pie-

t

\\..\—

\-.\^*

""//

/

>..

01-05-94 02-28-94 10-18-94

Sample Date


I

1. Use competent hydrogeologists to adequately characterizethe site and put performance based language intocontracts.

2. Select a drilling method that will minimize formationdamage. For unconsolidated formations, cable tool andpercussion hammer methods are the best means of drillingmonitoring wells followed by wet rotary and air.

3. Design the well to the formation by requiring appropriatesampling and testing of geological material. Avoid the "onesize fits all" philosophy.

4. Pre-develop wells to ensure stabilization of the sand pack.5. Maximize well development by initial surging followed by

pumping the well at a rate that truly stresses the formation.6. Provide dedicated pumping devices in each well to eliminate

field variability issues and minimize statistical errors.7. Stipulate Data Quality Objectives in laboratory contracts.

Conduct regular audits and require the lab to participate inscheduled performance evaluation analyses.

8. Use appropriate statistical methods that apply to eachmonitoring well and develop a minimum of eight quarterlybackground samples prior to conducting statisticalanalyses.


REFERENCES

Aller, Linda, et al., 1989. Handbook of Suggested Practices for thedesign and Installation of Ground-Water Monitoring Wells.EPA/600/4-89/034, 398 pp.

Backhus, D.A., et al., 1993. Sampling colloids and colloid-associatedcontaminants in ground water. Ground Water, Vol. 31, No. 3, pp.466-479.

Barcelona, M.J., et al., 1983. a Guide to the Selection of Materials forMonitoring Well Construction and Ground-Water Sampling. IllinoisState Water Survey Contract Report 327, 78 p.

Barcelona, M.J., et al., 1985. Practical Guide for Ground-WaterSampling. EPA/6002-85/104, 169 p.

Barcelona, M. J., et al., 1994. Reproducible well purging procedures andVOC stabilization criteria for ground-water sampling. GroundWater, Vol. 32, No. 1, pp, 12-22.

Boettner, E.A., et al., 1981. Organic and Ortanotin Compounds Leachedfrom PVC and CPVC Pipe. USEPA Document No. 600/1-81-062,102 p.

Bureau of National Affairs, Inc., April 20, 1990. Browning-FerrisIndustries of South Jersey Inc. v. EPA, pp.1081-1092.

Davis, C., and McNichols, R., 1994. Ground Water Monitoring StatisticsUpdate: Parti: Progress Since 1988. Ground Water Monitoring& Remediation, Vol. 14, No. 4, pp. 148-158.

Edberg, Jeffrey, 1994. Low-Tech Drilling for High-Tech Clients:Advantages of the Cable Tool Drilling Method. Water WellJournal, Vol. 48, No. 5, pp. 56-58.

Everett, Lome G., 1980. Groundwater Monitoring. General ElectricCompany, Schenectady, N.Y., 440 pp.

Gass, T.E., et al., 1991. Test Results of the Grundfos Ground-WaterSampling Pump. Proceedings of the Fifth National Symposium ofAquifer Restoration and Ground Water Monitoring.


Gibbons, R.D., 1990. A General Statistical Procedure for Ground-WaterDetection Monitoring at Waste Disposal Facilities. Ground Water28: 235-243.

Gibbons, R.D., 1991. Some Additional Nonparametric Prediction Limitsfor Ground-Water Detection Monitoring at Waste DisposalFacilities. Ground Water 29: 729-736.

' Gibs, J. and T.E. Imbtigiotta, 1990. Well purging criteria for samplingpurgeable organic compounds. Ground Water. Vol. 28, No. 1,

I pp. 68-78.i

Hem, J.D., 1985. Study and Interpretation of the ChemicalCharacteristics of Natural Water. .USGS Water-Supply Paper

J. 2254, 263 p.

Humenick, M.J., et al., 1980. Methodology for Monitoring GroundWater at Uranium Solution Mines. Ground Water, Vol. 18, No. 3,pp. 262-273.

Llopis, Jose L., 1991. The Effects of Well Casing Material on GroundWater-Quality. USEPA Ground-Water Issue, EPA/540/4-91/005,15 p.

Nielsen, David M., 1993. The Relationship of Monitoring Well Design,Construction and Development to Turbidity in Wells, and RelatedImplications for Groundwater Sampling. Ground Water Sampling-A Workshop Summary, EPA/600/R-94/205, p. 16.

Oakley, D., and Korte, N.E., 1996. Nickel and Chromium in GroundWater Samples as Influenced by Well Construction and SamplingMethods. Ground Water Monitoring & Remediation, Vol. 16,No.1, pp93-99.

i Oneacre, J. W., 1992. Solid Waste- Principles and Practice in theUnited States. International Conference on EnvironmentalProtection and Control Technology, Ensearch, Kuala Lumpur,Malaysia, pp. 661-674.

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Parker, Louise V. and Thomas A. Ranney, 1994. Effect ofConcentration on Sorption of Dissolved Organics by PVC, PTFE,and Stainless Steel Well Casings. Ground Water Monitoring &Remediation, Vol. 14, No. 3, pp. 139-149.

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SFUND RECORDS CTR 2073226 · 2016. 12. 20. · SFUND RECORDS CTR 2073226 Reprinted from UNCERTAINTY IN THE GEOLOGIC ENVIRONMENT: From Theory to Practice Proceedings of Uncertainty