Compendium of ERT Groundwater Sampling Procedures · Compendium of ERT Groundwater Sampling...

United StatesEnvironmental ProtectionAgency

Office of Solid Waste andEmergency ResponseWashington DC 20460

EPA/540/P-91/007January 1999 O S W E R 9 3 6 0 . 4 - 0 6

Compendium of ERTGroundwater SamplingProcedures

Interim Final

EPA/540/P-91/007OSWER Directive 9360.4-06

January 1991

COMPENDIUM OF ERT GROUNDWATERSAMPLING PROCEDURES

Sampling Equipment Decontamination

Groundwater Well Sampling

Soil Gas Sampling

Monitoring Well Installation

Water Level Measurement

Well Development

Controlled Pumping Test

Slug Test

Environmental Response TeamEmergency Response Division

Office of Emergency and Remedial ResponseU.S. Environmental Protection Agency

Washington, DC 20460

Notice

This document has been reviewed in accordance with U.S. Environmental Protection Agency policy and approvedfor publication. Mention of trade names or commercial products does not constitute endorsement orrecommendation for use.

The policies and procedures established in this document are intended solely for the guidance of governmentpersonnel, for use in the Superfund Removal Program. They are not intended, and cannot be relied upon, tocreate any rights, substantive or procedural, enforceable by any party in litigation with the United States. TheAgency reserves the right to act at variance with these policies and procedures and to change them at any timewithout public notice.

Depending on circumstances and needs, it may not be possible or appropriate to follow these procedures exactlyin all situations due to site conditions, equipment limitations, and limitations of the standard procedures.Whenever these procedures cannot be followed as written, they may be used as general guidance with any andall modifications fully documented in either QA Plans, Sampling Plans, or final reports of results.

Each Standard Operating Procedure in this compendium contains a discussion on quality assurance/qualitycontrol (QA/QC). For more information on QA/QC objectives and requirements, refer to the QualityAssurance/Quality Control Guidance for Removal Activities, OSWER directive 9360.4-01, EPA/540/G-90/004.

Questions, comments, and recommendations are welcomed regarding the Compendium of ERT GroundwaterSampling Procedures. Send remarks to:

Mr. William A. CoakleyRemoval Program QA Coordinator

U.S. EPA - ERTRaritan Depot - Building 18, MS-101

2890 Woodbridge AvenueEdison, NJ 08837-3679

For additional copies of the Compendium of ERT Groundwater Sampling Procedures, please contact:

National Technical Information Service (NTIS)U.S. Department of Commerce

5285 Port Royal RoadSpringfield, VA 22161

(703) 487-4600

Table of Contents

Section

1.0 SAMPLING EQUIPMENT DECONTAMINATION: SOP #2006

1.1 Scope and Application1.2 Method Summary1.3 Sample Preservation, Containers, Handling, and Storage1.4 Interferences and Potential Problems1.5 Equipment/Apparatus1.6 Reagents1.7 Procedures

1.7.1 Decontamination Methods 2

1.7.2 Field Sampling Equipment Cleaning Procedures 3

1.8 Calculations1.9 Quality Assurance/Quality Control1.10 Data Validation1.11 Health and Safety

2.0 GROUNDWATER WELL SAMPLING: SOP #2007

2.12.22.32.4

Scope and ApplicationMethod SummarySample Preservation, Containers, Handling and StorageInterferences and Potential Problems

2.4.1 General 5

2.4.2 Purging 5

2.4.3 Materials 6

2.5 Equipment/Apparatus 6

2.51 General2.52 Bailer2.5.3 Submersible Pump2.5.4 Non-Gas Contact Bladder Pump2.5.5 Suction Pump2.5.6 Inertia Pump

2.6 Reagents 8

2.7 Procedures 8

2.7.1 Preparation2.7.2 Field Preparation2.7.3 Evacuation of Static Water (Purging)2.7.4 Sampling2.7.5 Filtering2.7.6 Post Operation2.7.7 Special Considerations for VOA Sampling

iii

889

11131313

Section

2.8 Calculations 142.9 Quality Assurance/Quality Control 142.10 Data Validation 152.11 Health and Safety 15

3.0 SOIL GAS SAMPLING: SOP #2149

3.1 Scope and Application3.2 Method Summary3.3 Sample Preservation, Containers, Handling, and Storage

3.4

3.3.1 Tedlar Bag3.3.2 Tenax Tube3.3.3 SUMMA Canister

Interferences and Potential Problems

3.5

3.4.1 HNU Measurements3.4.2 Factors Affecting Organic Concentrations in Soil Gas3.4.3 Soil Probe Clogging3.4.4 Underground Utilities

Equipment/Apparatus

3.63.7

3.5.1 Slam Bar Method3.5.2 Power Hammer Method

ReagentsProcedures

3.8

3.7.1 Soil Gas Well Installation3.7.2 Screening with Field Instruments3.7.3 Tedlar Bag Sampling3.7.4 Tenax Tube Sampling3.7.5 SUMMA Canister Sampling

Calculations

3.9

3.8.1 Field Screening Instruments3.8.2 Photovac GC Analysis

Quality Assurance/Quality Control

171717

171717

18

18181818

18

1819

1919

1920202022

22

2222

22

3.9.1 Field Instrument Calibration 223.9.2 Gilian Model HFS113A Air Sampling Pump Calibration 223.9.3 Sample Probe Contamination 223.9.4 Sample Train Contamination 223.9.5 Field Blank 223.9.6 Trip Standard 223.9.7 Tedlar Bag Check 233.9.8 SUMMA Canister Check 23

iv

Section

4.0

3.9.9 Options

3.10 Data Validation3.11 Health and Safety

MONITORING WELL INSTALLATION: SOP #2150

4.1 Scope and Application 2 54.2 Method Summary 25

4.34.44.54.64.7

4.84.94.104.11

4.2.1 Hollow Stem Augering4.2.2 Cable Tool Drilling4.2.3 Rotary Drilling

Sample Preservation, Containers, Handling, and StorageInterferences and Potential ProblemsEquipment/ApparatusReagentsProcedures

25252 5

252 6262 62 6

4.7.1 Preparation4.7.2 Field Preparation4.7.3 Well Construction

2 62 628

CalculationsQuality Assurance/Quality ControlData ValidationHealth and Safety

2930303 0

5.0 WATER LEVEL MEASUREMENT: SOP #2151

5.1 Scope and Application 31

5.2 Method Summary 31

5.3 Sample Preservation, Containers, Handling and Storage 31

5.4 Interferences and Potential Problems 315.5 Equipment/Apparatus 32

5.6 Reagents 3 2

5.7 Procedures 3 2

5.7.1 Preparation 325.7.2 Procedures 3 2


33333333

2323

Section

6.0 WELL DEVELOPMENT: SOP #2156

6.1 Scope and Application6.2 Method Summary6.3 Sample Preservations, Containers, Handling, and Storage6.4 Interferences and Potential Problems6.5 Equipment/Apparatus6.6 Reagents6.7 Procedures

6.7.1 Preparation6.7.2 Operation6.7.3 Post Operation


7.0 CONTROLLED PUMPING TEST: SOP #2157

7.1 Scope and Application7.2 Method Summary7.3 Sample Preservation, Containers, Handling, and Storage7.4 Interferences and Potential Problems7.5 Equipment/Apparatus7.6 Reagents7.7 Procedures

7.7.1 Preparation7.7.2 Field Preparation7.7.3 Pre-Test Monitoring7.7.4 Step Test7.7.5 Pump Test7.7.6 Post Operation


8.0 SLUG TEST: SOP #2158

8.1 Scope and Application8.2 Method Summary8.3 Sample Preservation, Containers, Handling and Storage8.4 Interferences and Potential Problems8.5 Equipment/Apparatus8.6 Reagents8.7 Procedures

3 53 53 535353 63 6

3 63 637

3 7373838

3 93 93939394 04 0

404 0404 04142

4 34 3434 3

4545454 54 54545

vi

Section

8.7.1 Field Procedures8.7.2 Post Operation


APPENDIX A - Sampling Train Schematic

APPENDIX B - HNU Field Protocol

APPENDIX C - Forms

REFERENCES

Page

4547

47474848

51

55

61

vii

Exhibit

Table 1:

Table 2:

Table 3:

Table 4:

Table 5:

Figure 1: Sampling Train Schematic #2149

Forms: Well Completion Form #2150

List of Exhibits

SOP

Recommended Solvent Rinse for Soluble Contaminants #2006

Advantages and Disadvantages of Various Groundwater #2007Sampling Devices

Advantages and Disadvantages of Various DrillingTechniques

#2150 27

Time Intervals for Measuring Drawdown in thePumped Well

#2157 41

Time Intervals for Measuring Drawdown in anObservation Well

#2157 41

Groundwater Level Data Form #2151

Pump/Recovery Test Data Sheet #2157

Slug Test Data Form #2158

viii

Page

4

7

50

56

57

58

60

Acknowledgments

Preparation of this document was directed by William A. Coakley, the Removal Program QA Coordinator ofthe Environmental Response Team, Emergency Response Division. Additional support was provided under U.S.EPA contract #68-03-3482 and U.S. EPA contract #68-WO-0036.

ix

1.0 SAMPLING EQUIPMENT DECONTAMINATION: SOP #2006

1.1 SCOPE AND APPLICATION

This Standard Operating Procedure (SOP) describesmethods used for preventing or reducing cross-contamination, and provides general guidelines forsampling equipment decontamination procedures ata hazardous waste site. Preventing or minimizingcross-contamination in sampled media and insamples is important for preventing the introductionof error into sampling results and for protecting thehealth and safety of site personnel.

Removing or neutralizing contaminants that haveaccumulated on sampling equipment ensuresprotection of personnel from permeating substances,reduces or eliminates transfer of contaminants toclean areas, prevents the mixing of incompatiblesubstances, and minimizes the likelihood of samplecross-contamination.

1.2 METHOD SUMMARY

Contaminants can be physically removed fromequipment, or deactivated by sterilization ordisinfection. Gross contamination of equipmentrequires physical decontamination, includingabrasive and non-abrasive methods. These includethe use of brushes, air and wet blasting, and high-pressure water cleaning, followed by a wash/rinseprocess using appropriate cleaning solutions. Useof a solvent rinse is required when organiccontamination is present.

1.3 SAMPLE PRESERVATION,CONTAINERS, HANDLING, ANDSTORAGE

This section is not applicable to this SOP.

1.4 INTERFERENCES ANDPOTENTIAL PROBLEMS

?? The use of distil led/deionized watercommonly available from commercialvendors m a y b e a c c e p t a b l e f o rdecontamination of sampling equipment

1.5

?

provided that it has been verified bylaboratory analysis to be analyte free.

An untreated potable water supply is notan acceptable substitute for tap water. Tapwater may be used from any municipalwater treatment system for mixing ofdecontamination solutions.

Acids and so lven ts u t i l i zed in thedecontamination sequence pose the healthand safety risks of inhalation or skincontact, and raise shipping concerns ofpermeation or degradation.

The site work plan must address disposalof the spent decontamination solutions.

Several procedures can be established tominimize contact with waste and thepotential for contamination. For example:

S t r e s s w o r k p r a c t i c e s t h a tminimize contact with hazardoussubstances.

Use remote sampling, handling,and container-opening techniqueswhen appropriate.

Cover monitoring and samplingequipment with protective materialto minimize contamination.

Use disposable outer garmentsa n d d i s p o s a b l e s a m p l i n gequipment when appropriate.

EQUIPMENT/APPARATUS

appropriate personal protective clothingnon-phosphate detergentselected solventslong-handled brushesdrop cloths/plastic sheetingtrash containerpaper towelsgalvanized tubs or bucketstap water

?

1.6

distilled/deionized watermetal/plastic containers for storage anddisposal of contaminated wash solutionsp r e s s u r i z e d s p r a y e r s f o r t a p a n ddeionized/distilled watersprayers for solventstrash bagsaluminum foilsafety glasses or splash shieldemergency eyewash bottle

REAGENTS

There are no reagents used in this procedure asidefrom the actual decontamination solutions andsolvents. In general, the following solvents areutilized for decontamination purposes:

?? 10% nitric acid(1)?? acetone (pesticide grade)(*)?? hexane (pesticide grade)(*)? methanol

(1) Only if sample is to be analyzed for trace metals.(2) Only if sample is to be analyzed for organics.

1.7 PROCEDURES

As part of the health and safety plan, develop andset up a decontamination plan before any personnelor equipment enter the areas of potential exposure.The equipment decontamination plan shouldinclude:

? the number, location, and layout ofdecontamination stations

? which decontamination apparatus is needed

• the appropriate decontamination methods

. methods for disposal of contaminatedclothing, apparatus, and solutions

1.7.1 Decontamination Methods

All personnel, samples, and equipment leaving thecontaminated area of a silt must bedecontaminated. Various decontamination methodswill eithcr physically remove contaminants,inactivate contaminants by disinfection orsterilization, or do hot h.

In many cases, gross contamination can be removedby physical means. The physical decontaminationtechn iques a p p r o p r i a t e f o r e q u i p m e n tdecontamina t ion can be g rouped in to twocategories: abrasive methods and non-abrasivemethods.

Abrasive Cleaning Methods

Abrasive cleaning methods work by rubbing andwearing away the top layer of the surface containingthe contaminant. The following abrasive methodsarc available:

?? Mechanical: Mechanical cleaning methodsuse brushes of metal or nylon. Theamount and type of contaminants removedwill vary with the hardness of bristles,length of brushing time, and degree ofbrush contact.

?

.

Air Blasting: Air blasting is used forc lean ing l a rge equ ipment , such asbulldozers, drilling rigs or auger bits. Theequipment used in air blast cleaningemploys compressed air to force abrasivematerial through a nozzle at high velocities.The distance between the nozzle and thesurface cleaned, as well as the pressure ofair, the time of application, and the angleat which the abrasive strikes the surface,determines cleaning efficiency. Air blastinghas several disadvantages: it is unable tocontrol the amount of material removed, itcan acrate contaminants, and it generateslarge amounts of waste.

Wet Blasting: Wet blast cleaning, alsoused to clean large equipment, involves useof a suspended fine abrasive: delivered bycompressed air to the contaminated area.The amount of materials removed can becarefully controlled by using wry lineabrasives. This method generates a largeamount of waste.

Non-Abrasive Cleaning Methods

Non-abrasive cleaning methods work by forcing thecontaminant off of a surface with pressure. Ingeneral, less of the equipment surface is removedusing non-ahrasive methods. The following non-abrasive methods arc available:

?? High-Pressure Water: This methodconsists of a high-pressure pump, anoperator-controlled directional nozzle, anda high pressure hose. Operating pressureusually ranges from 340 to 680 atmospheres(atm) which relates to flow rates of 20 to140 liters per minute.

?? Ultra-High-Pressure Water: This systemproduces a pressurized water jet (from1,000 to 4,000 atm). The ultra-high-pressure spray removes tightly-adheredsurface film. The water velocity rangesfrom 500 m/sec (l,000 atm) to 900 m/sec(4,000 atm). Additives can enhance themethod. This method is not applicable forhand-held sampling equipment.

Disinfection/Rinse Methods

?? Disinfection: Disinfectants are a practicalmeans of inactivating infectious agents.

?? Sterilization: Standard sterilizationmethods involve heating the equipment.Sterilization is impractical for largeequipment.

?? Rinsing: Rinsing removes contaminantsthrough dilution, physical attraction, andsolubilization.

1.7.2 Field Sampling EquipmentCleaning Procedures

Solvent rinses are not necessarily required whenorganics are not a contaminant of concern and maybe eliminated from the sequence specified below.Similarly, an acid rinse is not required if analysisdoes not include inorganics.

1. Where applicable, follow physical removalprocedures specified in section 1.7.1.

2. Wash equipment with a non-phosphatedetergent solution.

3. Rinse with tap water.

4. Rinse with distilled/deionized water.

5. Rinse with 10% nitric acid if the sample will beanalyzed for trace organics.

6. Rinse with distilled/deionized water.

7. Use a solvent rinse (pesticide grade) if thesample will be analyzed for organics.

8. Air dry the equipment completely.

9. Rinse again with distilled/deionized water.

Selection of the solvent for use in thedecon tamina t ion p rocess i s based on thecontaminants present at the site. Use of a solventis required when organic contamination is presenton-site. Typical solvents used for removal oforganic contaminants include acetone, hexane, orwater. An acid rinse step is required if metals arepresent on-site. If a particular contaminant fractioni s no t p resen t at the site, the nine-stepdecontamination procedure listed above may bemodified for site specificity. The decontaminationsolvent used should not be among the contaminantsof concern at the site.

Table 1 lists solvent rinses which may be requiredfor elimination of particular chemicals. After eachsolvent rinse, the equipment should be air dried andrinsed with distilled/deionized water.

Sampling equipment that requires the use of plastictubing should be disassembled and the tubingreplaced with clean tubing, before commencementof sampling and between sampling locations.

1.8 CALCULATIONS


1.9 QUALITY ASSURANCE/QUALITY CONTROL

One type of quality control sample specific to thefield decontamination process is the rinsate blank.The rinsate blank provides information on theeffectiveness of the decontamination processemployed in the field. When used in conjunctionwith field blanks and trip blanks, a rinsate blank candetect contamination during sample handling,storage and sample transportation to the laboratory.

3

Table 1: Recommended Solvent Rinse for Soluble Contaminants

SOLVENT SOLUBLE CONTAMINANTS

Water ?? Low-chain hydrocarbons?? Inorganic compounds

? Some organic acids and other polar compounds

Dilute Acids ?? Basic (caustic) compounds?? Amines?? Hydrazines

Dilute Bases -- for example, detergent ?? Metalsand soap • Acidic compounds

?? Phenol? Thiols? Some nitro and sulfonic compounds

Organic Solvents(1) - for example, ? Nonpolar compounds (e.g., some organic compounds)alcohols, ethers, ketones, aromatics,straight-chain alkanes (e.g., hexane), andcommon petroleum products (e.g., fuel,oil, kerosene)

(1) - WARNING: Some organic solvents can permeate and/or degrade protective clothing.

A rinsate blank consists of a sample of analyte-free(i.e, deionized) water which is passed over andthrough a field decontaminated sampling device andplaced in a clean sample container.

Rinsate blanks should be run for all parameters ofinterest at a rate of 1 per 20 for each parameter,even if samples are not shipped that day. Rinsateblanks are not required if dedicated samplingequipment is used.

1.10 DATA VALIDATION


1.11 HEALTH AND SAFETY

When working with potentially hazardous materials,follow U.S. EPA, OSHA and specific health andsafety procedures.

Decontamination can pose hazards under certaincircumstances even though performed to protect

health and safety. Hazardous substances may beincompatible with decontamination methods. Forexample, the decontamination solution or solventmay react with contaminants to produce heat,explosion, or toxic products. Decontaminationmethods may be incompatible with clothing orequipment; some solvents can permeate or degradeprotective clothing. Also, decontamination solutionsand solvents may pose a direct health hazard toworkers through inhalation or skin contact, or ifthey combust.

The decontamination solutions and solvents must bedetermined to be compatible before use. Anymethod that permeates, degrades, or damagespersonal protective equipment should not be used.If decontamination methods pose a direct healthhazard, measures should be taken to protectpersonnel or the methods should be modified toeliminate the hazard.

4

2.0 GROUNDWATER WELL SAMPLING: SOP #2007


The objective of this Standard Operating Procedure(SOP) is to provide general reference informationon sampling of groundwater wells. This guideline isprimarily concerned with the collection of watersamples from the saturated zone of the subsurface.Every effort must be made to ensure that thesample is representative of the particular zone ofwater being sampled. These procedures aredesigned to be used in conjunction with analyses forthe most common types of groundwatercontaminants (e.g., volatile and semi-volatile organiccompounds, pesticides, metals, biologicalparameters).

2.2 METHOD SUMMARY

Prior to sampling a monitoring well, the well mustbe purged. This may be done with a number ofinstruments. The most common of these are thebailer, submersible pump, non-gas contact bladderpump and inertia pump. At a minimum, three wellvolumes should be purged, if possible. Equipmentmust be decontaminated prior to use and betweenwells. Once purging is completed and the correctlaboratory-cleaned sample containers have beenprepared, sampling may proceed. Sampling may beconducted with any of the above instruments, andneed not be the same as the device used forpurging. Care should be taken when choosing thesampling device as some will affect the integrity ofthe sample. Sampling equipment must also bedecontaminated. Sampling should occur in aprogression from the least to most contaminatedwe11, if this information is known.


The type of analysis for which a sample is beingcollected determines the type of bottle, preservative,holding time, and filtering requirements. Samplesshould be collected directly from the samplingdevice into appropriate laboratory-cleanedcontainers. Check that a Teflon liner is present in

the cap, if required. Attach a sample identificationlabel. Complete a field data sheet, a chain ofcustody form and record all pertinent data in thesite logbook.

Samples shall be appropriately preserved, labelled,logged, and placed in a cooler to be maintained at4°C. Samples must be shipped well before theholding time is over and ideally should be shippedwithin 24 hours of sample collection. It isimperative that these samples be shipped ordelivered daily to the analytical laboratory in orderto maximize the time available for the laboratory toperform the analysis. The bottles should be shippedwith adequate packing and cooling to ensure thatthey arrive intact.

Certain conditions may require special handlingtechniques. For example, treatment of a sample forvolatile organic (WA) analysis with sodiumthiosulfate preservative is required if there isresidual chlorine in the water (such as public watersupply) that could cause free radical chlorinationand change the identity of the original contaminants.However, sodium thiosulfate should not be used ifchlorine is not present in the water. Specialrequirements must be determined prior toconducting fieldwork.


2.4.1 General

The primary goal of groundwater sampling is toobtain a representative sample of the groundwaterbody. Analysis can be compromised by fieldpersonnel in two primary ways: (1) taking anunrepresentative sample, or (2) by incorrecthandling of the sample. There are numerous waysof introducing foreign contaminants into a sample,and these must be avoided by following strictsampling procedures and only utilizing trained fieldpersonnel.

2.4.2 Purging

In a non-pumping well, there will be little or novertical mixing of the water, and stratification will

5

occur. The well water in the screened section willmix with the groundwater due to normal flowpatterns, but the well water above the screenedsection will remain isolated, become stagnant andlack the VOAs representative of the groundwater.Sampling personnel should realize that stagnantwater may contain foreign material inadvertently ordeliberately introduced from the surface, resultingin an unrepresentative sample. To safeguardagainst collecting nonrepresentative stagnant water,follow these guidelines during sampling:

?? As a general rule, all monitoring wellsshould be pumped or bailed prior tosampling. Purge wa te r shou ld becontainerized on site or handled asspecified in the site-specific project plan.Evacuation of a minimum of one volume ofwater in the well casing, and preferablythree to five volumes, is recommended fora representative sample. In a high-yieldingground water formation and where there isno stagnant water in the well above thescreened section, evacuation prior tosample withdrawal is not as critical.However, in all cases where the monitoringdata is to be used for enforcement actions,evacuation is recommended.

? For wells that can be pumped or bailed todryness with the equipment being used, thewell should be evacuated and allowed torecover prior to sample withdrawal. If therecovery rate is fairly rapid and theschedule allows, evacuation of more thanone volume of water is preferred. Ifrecovery is slow, sample the well uponrecovery after one evacuation.

? A nonrepresentative sample can also resultfrom excessive pre-pumping of themonitoring well. Stratification of theleachate concentration in the groundwaterformation may occur, or heavier-than-watercompounds may sink to the lower portionsof the aquifer. Excessive pumping cand i lu te o r inc rease the con taminan tconcentrations from what is representativeof the sampling point of interest.

2.4.3 Materials

Samplers and evacuation equipment (bladders,pumps, bailers, tubing, etc.) should be limited to

those made with stainless steel, Teflon, and glass inareas where concentrations are expected to be at ornear the detection limit. The tendency of organicsto leach into and out of many materials make theselection of materials critical for trace analyses.The use of plastics, such as PVC or polyethylene,should be avoided when analyzing for organics.However, PVC may be used for evacuationequipment as it will not come in contact with thesample.

Table 2 on page 7 discusses the advantages anddisadvantages of certain equipment.

EQUIPMENT/APPARATUS

General

water level indicator- electric sounder- steel tape- transducer- reflection sounder- airlinedepth sounderappropriate keys for well cap lockssteel brushH N U o r O V A ( w h i c h e v e r i s m o s tappropriate)logbookcalculatorfield data sheetschain of custody formsforms and sealssample containersEngineer’s rulesharp knife (locking blade)tool box (to include at least: screwdrivers,pliers, hacksaw, hammer, flashlight,adjustable wrench)leather work glovesappropriate health and safety gear5-gallon pailplastic sheetingshipping containerspacking materialsbolt cuttersZiploc plastic bagscontainers for evacuation of liquidsdecontamination solutionstap waternon-phosphate soapseveral brushes

Table 2: Advantages and Disadvantagesof Various Groundwater Sampling Devices

Device

Bailer

Advantages

?? The only practical limitations are size andmaterials

?? No power source needed?? Portable

Disadvantages

?? Time consuming, especially for large wells?? Transfer of sample may cause aeration

?? Inexpensive; it can be dedicated and hung in awell reducing the chances of cross-contamination

?? Minimal outgassing of volatile organics whilesample is in bailer

?? Readily available?? Removes stagnant water first?? Rapid, simple method for removing small

volumes of purge water

SubmersiblePump

?? Portable; can be used on an unlimited numberof wells

?? Relatively high pumping rate (dependent ondepth and size of pump)

?? Generally very reliable; does not requirepriming

?? Potential for effects on analysis of traceorganics

?? Heavy and cumbersome, particularly indeeper wells

?? Expensive?? Power source needed?? Susceptible to damage from silt or sediment?? Impractical in low yielding or shallow wells

Non-Gas Contact ?? Maintains integrity of sample ?? Difficult to clean although dedicated tubingBladder Pump ?? Easy to use and bladder may be used

?? Only useful to approximately 100 feet indepth

?? Supply of gas for operation (bottled gasand/or compressor) is difficult to obtainand is cumbersome

Suction Pump ?? Portable, inexpensive, and readily available ?? Only useful to approximately 25 feet or lessin depth

?? Vacuum can cause loss of dissolved gasesand volatile organics

?? Pump must be primed and vacuum is oftendifficult to maintain

?? May cause pH modification

Inertia Pump ?? Portable, inexpensive, and readily available?? Rapid method for purging relatively shallow

wells

?? Only useful to approximately 70 feet or lessin depth

?? May be time consuming to use?? Labor intensive?? WaTerra pump is only effective in 2-inch

diameter wells

pails or tubsaluminum foilgarden sprayerpreservativesdistilled or deionized water

Bailer

clean, decon tamina ted ba i l e r ( s ) o fappropriate size and construction materialnylon line, enough to dedicate to each wellTeflon-coated bailer wiresharp knifealuminum foil (to wrap clean bailers)5-gallon bucket

Submersible Pump

pump(s)generator (110, 120, or 240 volt) or 12-voltbattery if inaccessible to field vehiclel-inch black PVC coil pipe -- enough todedicate to each wellhose clampssafety cabletool box supplement- pipe wrenches, 2- wire strippers- electrical tape- heat shrink- hose connectors- Teflon tapewinch or pulleygasoline for generatorflow meter with gate valvel-inch nipples and various plumbing (i.e.,pipe connectors)

Non-Gas Contact Bladder Pump

non-gas contact bladder pumpcompressor or nitrogen gas tankbatteries and chargerTeflon tubing -- enough to dedicate to eachwellSwagelock fittingtoolbox supplements -- s a m e a ssubmersible pump

2.5.5 Suction Pump

pumpblack coil tubing -- enough to dedicate to

?? plumbing fittings? flow meter with gate valve

2.5.6 Inertia Pump

?? pump assembly (WaTerra pump, pistonPump)

?? 5-gallon bucket

2.6 REAGENTS

Reagents will be utilized for preservation of samplesand for decontamination of sampling equipment.The preservation required is specified by theanalysis to be performed. Decontaminationsolutions are specified in ERT SOP #2006,Sampling Equipment Decontamination.

2.7 PROCEDURES

2.7.1 Preparation

1. Determine the extent of the sampling effort,the sampling methods to be employed, andwhich equipment and supplies are needed.

2. Obtain necessary sampling and monitoringequipment.

3. Decontaminate or preclean equipment, andensure that it is in working order.

4. Prepare scheduling and coordinate with staff,clients, and regulatory agency, if appropriate.

5. Perform a general site survey prior to site entryin accordance with the site-specific health andsafety plan.

6. Identify and mark all sampling locations.

2.7.2 Field Preparation

1. Start at the least contaminated well, if known.

2. Lay plastic sheeting around the well tominimize likelihood of contamination ofequipment from soil adjacent to the well.

each well

3.

4.

5.

6.

7.

8.

9.

10.

Remove locking well cap, note location, time ofday, and date in field notebook or anappropriate log form.

Remove well casing cap.

Screen headspace of well with an appropriatemonitoring instrument to determine thepresence of volatile organic compounds andrecord in site logbook.

However, monitoring for defining a contaminantplume requires a representative sample of a smallvolume of the aquifer. These circumstances requirethat the well be pumped enough to remove thestagnant water but not enough to induce flow fromother areas. Generally, three well volumes areconsidered effective, or calculations can be made todetermine, on the basis of the aquifer parametersand well dimensions, the appropriate volume toremove prior to sampling.

Lower water level measuring device or During purging, water level measurements may beequivalent ( i .e . , permanently installed taken regularly at 15- to 30-second intervals. Thistransducers or airline) into well until water data may be used to compute aquifer transmissivitysurface is encountered. and other hydraulic characteristics.

Measure distance from water surface toreference measuring point on well casing orprotective barrier post and record in sitelogbook. Alternatively, if there is no referencepoint, note that water level measurement isfrom top of steel casing, top of PVC riser pipe,from ground surface, or some other position onthe well head.

The following well evacuation devices are mostcommonly used. Other evacuation devices areavailable, but have been omitted in this discussiondue to their limited use.

Bailer

Measure total depth of well (do this at leasttwice to confirm measurement) and record insite logbook or on log form.

Calculate the volume of water in the well andthe volume to be purged using the calculationsin Section 2.8.

Bailers are the simplest purging device used andhave many advantages. They generally consist of arigid length of tube, usually with a ball check-valveat the bottom. A line is used to lower the bailerinto the well and retrieve a volume of water. Thethree most common types of bailer are PVC,Teflon, and stainless steel.

Select the appropriate purging and samplingequipment.

This manual method of purging is best suited toshallow or narrow diameter wells. For deep, largerdiameter wells which require evacuation of largevolumes of water, other mechanical devices may bemore appropriate.

2.7.3 Evacuation of Static Water(Purging)

The amount of flushing a well receives prior tosample collection depends on the intent of themonitoring program as well as the hydrogeologicconditions. Programs where overall qualitydetermination of water resources are involved mayrequire long pumping periods to obtain a samplethat is representative of a large volume of thataquifer. The pumped volume can be determinedprior to sampling so that the sample is a compositeof known volume of the aquifer, or the well can bepumped until the stabilization of parameters such astemperature, electrical conductance, or pH hasoccurred.

Bailing equipment includes a clean decontaminatedbailer, Teflon or nylon line, a sharp knife, andplastic sheeting.

1.

2.

3.

4.

9

Determine the volume of water to be purged asdescribed in Section 2.7.2, Field Preparation.

Lay plastic sheeting around the well to preventcontamination of the bailer line with foreignmaterials.

Attach the line to the bailer and lower until thebailer is completely submerged.

Pull bailer out ensuring that the line either fallsonto a clean area of plastic sheeting or nevertouches the ground.

5. Empty the bailer into a pail until full todetermine the number of bails necessary toachieve the required purge volume.

6. Thereafter, pour the water into a container anddispose of purge waters as specified in the site-specific project plan.

Submersible Pump

Submersible pumps are generally constructed ofplastic, rubber, and metal parts which may affect theanalysis of samples for certain trace organics andinorganics. As a consequence, submersible pumpsmay not be appropriate for investigations requiringanalyses of samples for trace contaminants.However, they are still useful for pre-samplepurging. However, the pump must have a checkvalve to prevent water in the pump and the pipefrom rushing back into the well.

Submersible pumps generally use one of two typesof power supplies, either electric or compressed gas.Electric pumps can be powered by a 12-volt DCrechargeable battery, or a 110- or 220-volt ACpower supply. Those units powered by compressedgas normally use a small electric compressor whichalso needs 12-volt DC or 110-volt AC power. Theymay also utilize compressed gas from bottles.Pumps differ according to the depth and diameterof the monitoring wells.

1. Determine the volume of water to be purged asdescribed in section 2.7.2, Field Preparation.

2. Lay plastic sheeting around the well to preventcontamination of pumps, hoses or lines withforeign materials.

3. Assemble pump, hoses and safety cable, andlower the pump into the well. Make sure thepump is deep enough so that purging does notevacuate all the water. (Running the pumpwithout water may cause damage.)

4. Attach flow meter to the outlet hose tomeasure the volume of water purged.

5. Attach power supply, and purge well untilspecified volume of water has been evacuated(or until field parameters, such as temperature,pH, conductivity, etc. have stabilized). Do notallow the pump to run dry. If the pumping rate

exceeds the well recharge rate, lower the pumpfurther into the well, and continue pumping.

6. Collect and dispose of purge waters as specifiedin the site-specific project plan.

Non-Contact Gas Bladder Pump

For this procedure, an all stainless-steel and TeflonMiddleburg-squeeze bladder pump (e.g., IEA,TIMCO, Well Wizard, Geoguard, and others) isused to provide the least amount of materialinterference to the sample (Barcelona, 1985).Water comes into contact with the inside of thebladder (Teflon) and the sample tubing, also Teflon,that may be dedicated to each well. Some wellsmay have permanently installed bladder pumps (i.e.,Well Wizard, Geoguard), that will be used tosample for all parameters.

1. Assemble Teflon tubing, pump and chargedcontrol box.

2. Use the same procedure for purging with abladder pump as for a submersible pump.

3. Be sure to adjust flow rate to prevent violentjolting of the hose as sample is drawn in.

Suction Pump

There are many different types of suction pumps.They include: centrifugal, peristaltic and diaphragm.Diaphragm pumps can be used for well evacuationat a fast pumping rate and sampling at a lowpumping rate. The peristaltic pump is a low-volumepump that uses rollers to squeeze the flexibletubing, thereby creating suction. This tubing can bededicated to a well to prevent cross-contamination.Peristaltic pumps, however, require a power source.

1. Assemble the pump, tubing, and power sourceif necessary.

2. To purge with a suction pump, follow the exactprocedures outlined for the submersible pump.

Inertia Pump

Inertia pumps, such as the WaTerra pump andpiston pump, are manually operated. They areappropriate to use when wells are too deep to bailby hand, but are not inaccessible enough to warrantan automatic (submersible, etc.) pump. These

10

Bailer

The positive-displacement volatile sampling bailer(by GPI) is perhaps the most appropriate forcollection of water samples for volatile analysis.Other bailer types (messenger, bottom fill, etc.) areless desirable, but may be mandated by cost and siteconditions. Generally, bailers can provide anacceptable sample, providing that samplingpersonnel use extra care in the collection process.

11

pumps are made of plastic and may be eitherdecontaminated or discarded, after use.

1.

2.

3.

4.

5.

Determine the volume of water to be purged asdescribed in Section 2.7.2, Field Preparation.

Lay plastic sheeting around the well to preventcontamination of pumps or hoses with foreignmaterials.

Assemble pump, and lower to the appropriatedepth in the well.

Begin pumping manually, discharging water intoa 5-gallon bucket (or other graduated vessel).Purge until specified volume of water has beenevacuated (or until field parameters such astemperature, pH, conductivity, etc. havestabilized).

Collect and dispose of purge waters as specifiedin the site-specific project plan.

2.7.4 Sampling

Sample withdrawal methods require the use ofpumps, compressed air, bailers, and samplers.Ideally, purging and sample withdrawal equipmentshould be completely inert, economical to use, easilycleaned, sterilized, reusable, able to operate atremote sites in the absence of power resources, andcapable of delivering variable rates for samplecollection.

There are several factors to take into considerationwhen choosing a sampling device. Care should betaken when reviewing the advantages ordisadvantages of any one device. It may beappropriate to use a different device to sample thanthat which was used to purge. The most commonexample of this is the use of a submersible pump topurge and a bailer to sample.

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

12.

Surround the monitoring well with clean plasticsheeting.

Attach a line to the bailer. If a bailer was usedfor purging, the same bailer and line may beused for sampling.

Lower the bailer slowly and gently into thewell, taking care not to shake the casing sidesor to splash the bailer into the water. Stoplowering at a point adjacent to the screen.

Allow bailer to fill and then slowly and gentlyretrieve the bailer from the well, avoidingcontact with the casing, so as not to knockflakes of rust or other foreign materials intothe bailer.

Remove the cap from the sample container andplace it on the plastic sheet or in a locationwhere it will not become contaminated. SeeSection 2.7.7 for special considerations on VOAsamples.

Begin pouring slowly from the bailer.

Filter and preserve samples as required bysampling plan.

Cap the sample container tightly and place pre-labeled sample container in a carrier.

Replace the well cap.

Log all samples in the site logbook and on fielddata sheets and label all samples.

Package samples and complete necessarypaperwork.

Transport sample to decontamination zone toprepare it for transport to analytical laboratory.

Submersible Pump

Although it is recommended that samples not becollected with a submersible pump due to thereasons stated in Section 2.4, there are somesituations where they may be used.

1. Allow the monitoring well to recharge afterpurging, keeping the pump just above thescreened section,

2.

3.

4.

5.

6.

7.

8.

9.

10.

Attach gate valve to hose (if not already fitted),and reduce flow of water to a manageablesampling rate.

3.

Assemble the appropriate bottles. 4.

If no gate valve is available, run the water downthe side of a clean jar and fill the samplebottles from the jar.

5.

6.Cap the sample container tightly and place pre-labeled sample container in a carrier.

7.Replace the we11 cap.

Log all samples in the site logbook and on thefield data sheets and label all samples.

8.


Transport sample to decontamination zone forprepara t ion fo r t r anspor t to ana ly t i ca llaboratory.

Upon completion, remove pump and assemblyand fully decontaminate prior to setting into thenext sample well. Dedicate the tubing to thehole.

9.

10.

11.

Non-Gas Contact Bladder Pump

The use of a non-gas contact positive displacementbladder pump is often mandated by the use ofdedicated pumps installed in wells. These pumpsare also suitable for shallow (less than 100 feet)wells. They are somewhat difficult to clean, butmay be used with dedicated sample tubing to avoidcleaning. These pumps require a power supply anda compressed gas supply (or compressor). Theymay be operated at variable flow and pressure ratesmaking them ideal for both purging and sampling.

Barcelona (1984) and Nielsen (1985) report that thenon-gas contact positive displacement pumps causethe least amount of alteration in sample integrity ascompared to other sample retrieval methods.

1. Allow well to recharge after purging.

2. Assemble the appropriate bottles.

Turn pump on, increase the cycle time andreduce the pressure to the minimum that willallow the sample to come to the surface.





Transport sample to decontamination zone forprepara t ion fo r t r anspor t to ana ly t i ca llaboratory.

On completion, remove the tubing from thewell and either replace the Teflon tubing andbladder with new dedicated tubing and bladderor rigorously decontaminate the existingmaterials.

Collect non-filtered samples directly from theoutlet tubing into the sample bottle.

For filtered samples, connect the pump outlettubing directly to the filter unit. The pumppressure should remain decreased so that thepressure build-up on the filter does not blowout the pump bladder or displace the filter.For the Geotech barrel f i l ter , no actualconnections are necessary so this is not aconcern.

Suction Pump

In view of the limitations of suction pumps, they arenot recommended for sampling purposes.

Inertia Pump

Inertia pumps may be used to collect samples. It ismore common, however, to purge with these pumpsand sample with a bailer.

1. Following well evacuation, allow the well torecharge.

2. Assemble the appropriate bottles.

12

3.

4.

5.

6.

7.

8.

9.

Since these pumps are manually operated, theflow rate may be regulated by the sampler.The sample may be discharged from the pumpoutlet directly into the appropriate samplecontainer.





Transport sample to decontamination zone forpreparation for transport to analyticallaboratory.

Upon completion, remove pump anddecontaminate or discard, as appropriate.

2.7.5 Filtering

For samples that require filtering, such as sampleswhich will be analyzed for total metals, the filtermust be decontaminated prior to use and betweenuses. Filters work by two methods. A barrel filtersuch as the “Geotech” filter works with a bicyclepump, which is used to build up positive pressure inthe chamber containing the sample. The sample isthen forced through the filter paper (minimum size0.45µ) into a jar placed underneath. The barrelitself is filled manually from the bailer or directlyvia the hose of the sampling pump. The pressuremust be maintained up to 30 psi by periodicpumping.

A vacuum type filter involves two chambers, theupper chamber contains the sample and a filter(minimum size 0.45µ ) divides the chambers.Using a hand pump or a Gilian type pump, air iswithdrawn from the lower chamber, creating avacuum and thus causing the sample to movethrough the filter into the lower chamber where itis drained into a sample jar, repeated pumping maybe required to drain all the sample into the lowerchamber. If preservation of the sample is necessary,this should be done after filtering.

2.7.6 Post Operation

After all samples are collected and preserved, thesampling equipment should be decontaminated priorto sampling another well. This will preventcross-contamination of equipment and monitoringwells between locations.

1. Decontaminate all equipment.

2. Replace sampling equipment in storagecontainers.

3. Prepare and transport water samples to thelaboratory. Check sample documentation andmake sure samples are properly packed forshipment.

2.7.7 Special Considerations for VOASampling

The proper collection of a sample for volatileorganics requires minimal disturbance of the sampleto limit volatilization and therefore a loss ofvolatiles from the sample.

Sample retrieval systems suitable for the validcollection of volatile organic samples are: positivedisplacement bladder pumps, gear drivensubmersible pumps, syringe samplers and bailers(Barcelona, 1984; Nielsen, 1985). Field conditionsand other constraints will limit the choice ofappropriate systems. The focus of concern must beto provide a valid sample for analysis, one which hasbeen subjected to the least amount of turbulencepossible.

The following procedures should be followed:

1. Open the vial, set cap in a clean place, andcollect the sample during the middle of thecycle. When collecting duplicates, collect bothsamples at the same time.

2. Fill the vial to just overflowing. Do not rinsethe vial, nor excessively overfill it. Thereshould be a convex meniscus on the top of thevial.

3. Check that the cap has not been contaminated(splashed) and carefully cap the vial. Place thecap directly over the top and screw downfirmly. Do not overtighten and break the cap.

13

4 Invert the vial and tap gently. Observe vial forat least 10 seconds. If an air bubble appears,discard the sample and begin again. It isimperative that no entrapped air is in thesample vial.

5. Immediately place the vial in the protectivefoam sleeve and place into the cooler, orientedso that it is lying on its side, not straight up.

6. The holding time for VOAs is 7 days. Samplesshould be shipped or delivered to the laboratorydaily so as not to exceed the holding time.Ensure that the samples remain at 4°C, but donot allow them to freeze.

2.8 CALCULATIONS

There are no calculations necessary to implementthis procedure. However, if it is necessary tocalculate the volume of the well, utilize thefollowing equation:

Well volume = nr²h (cf) [Equation l]

where:n =

r =radius of monitoring well (feet)height of the water column (feet)[This may be determined bysubtracting the depth to waterfrom the total depth of the well asmeasured from the same referencepoint.]

cf = conversion factor (gal/ft3) = 7.48gal/ft³ [In this equation, 7.48gal/ft3 is the necessary conversionfactor.]

Monitoring wells are typically 2, 3, 4, or 6 inches indiameter. If you know the diameter of themonitoring well, there are a number of standardconversion factors which can be used to simplify theequation above.

The volume, in gallons per linear foot, for variousstandard monitoring well diameters c a n b ecalculated as follows:

v = nr² (cf) [Equation 2)

where:V = volume in gallons per linear footn = pi

= radius of monitoring well (feet)cf = conversion factor (7.48 gal/ft³)

For a 2-inch diameter well, the volume in gallonsper linear foot can be calculated as follows:

V = nr² (cf) [Equation 2)= 3.14 (l/12 ft)² 7.48 gal/ft³= 0.1632 gal/ft

Remember that if you have a 2-inch diameter, wellyou must convert this to the radius in feet to beable to use the equation.

The volume in gallons per linear foot for thecommon size monitoring wells are as follows:

Well Diameter v (volume in gal/ft.)

2 inches 0.16323 inches 0.36724 inches 0.65286 inches 1.4688

If you utilize the conversion factors above, Equation1 should be modified as follows:

Well volume = (h)(v) [Equation 3)

where:h = height of water column (feet)V = volume in gallons per linear foot as

calculated from Equation 2


There are no specific quality assurance activitieswhich apply to the implementation of theseprocedures. However, the following general QAprocedures apply:

? All data must be documented on field datasheets or within site logbooks.

?? All instrumentation must be operated inaccordance with operating instructions assupplied by the manufacturer, unless

14

otherwise specified in the work plan.Equipment checkout and calibrationactivities must o c c u r p r i o r t osampling/operation and they must bedocumented.




When working with potentially hazardous materials,follow U.S. EPA, OSHA and specific health andsafety procedures. More specifically, dependingupon the site-specific contaminants, variousprotective programs must be implemented prior tosampling the first well. The site health and safetyplan should be reviewed with specific emphasisplaced on the protection program planned for thewell sampling tasks. Standard safe operatingpractices should be followed such as minimizingcontact with potential contaminants in both thevapor phase and liquid matrix through the use ofrespirators and disposable clothing.

For volatile organic contaminants:

? Avoid breathing constituents venting fromthe well.

15

?? Pre-survey the well head-space with anFID/PID prior to sampling.

?? If monitoring results indicate organicconstituents, sampling activities may beconducted in Level C protection. At aminimum, skin protection will be affordedby disposable protective clothing.

Physical hazards associated with well sampling are:

? Lifting injuries associated with pump andbailer retrieval; moving equipment.

? Use of pocket knives for cutting dischargehose.

? Heat/cold stress as a result of exposure toextreme temperatures (may be heightenedby protective clothing).

?? Slip, trip, fall conditions as a result ofpump discharge.

? Restricted mobility due to the wearing ofprotective clothing.


Soil gas monitoring provides a quick means of wastesite evaluation. Using this method, undergroundcontamination can be identified, and the source,extent, and movement of the pollutants can betraced.

This Standard Operating Procedure (SOP) outlinesthe methods used by EPA/ERT in installing soil gaswells; measuring organic levels in the soil gas usingan HNU PI 101 Portable Photoionization Analyzerand/or other air monitoring devices; and samplingthe soil gas using Tedlar bags, Tenax sorbent tubes,and SUMMA canisters.

3.2 METHOD SUMMARY

A 3/8-inch diameter hole is driven into the groundto a depth of 4 to 5 feet using a commerciallyavailable “slam bar”. (Soil gas can also be sampledat other depths by the use of a longer bar or barattachments.) A l/Cinch O.D. stainless steel probeis inserted into the hole. The hole is then sealed atthe top around the probe using modeling clay. Thegas contained in the interstitial spaces of the soil issampled by pulling the sample through the probeusing an air sampling pump. The sample may bestored in Tedlar bags, drawn through sorbentcartridges, or analyzed directly using a directreading instrument.

The air sampling pump is not used for SUMMAcanister sampling of soil gas. Sampling is achievedby soil gas equilibration with the evacuatedSUMMA canister. Other field air monitoringdevices, such as the combustible gas indicator (MSACGI/02 Meter, Model 260) and the organic vaporanalyzer (Foxboro OVA, Model 128), can also beused depending on specific site conditions.Measurement of soil temperature u s i n g atemperature probe may also be desirable. Baggedsamples are usually analyzed in a field laboratoryusing a portable Photovac GC.

Power driven sampling probes may be utilized whensoil conditions make sampling by hand unfeasible(i.e., frozen ground, very dense clays, pavement,

3.0 SOIL GAS SAMPLING: SOP #2149

etc.). Commercially available soil gas samplingprobes (hollow, l/2inch O.D. steel probes) can bedriven to the desired depth using a power hammer(e.g., Bosch Demolition Hammer). Samples can bedrawn through the probe itself, or through Teflontubing inserted through the probe and attached tothe probe point. Samples are collected andanalyzed as described above.


3.3.1 Tedlar Bag

Soil gas samples are generally contained in 1-LTedlar bags. Bagged samples are best stored incoolers to protect the bags from any damage thatmay occur in the field or in transit. In addition,coolers ensure the integrity of the samples bykeeping them at a cool temperature and out ofdirect sunlight. Samples should be analyzed as soonas possible, preferably within 24 to 48 hours.

3.3.2 Tenax Tube

Bagged samples can also be drawn into Tenax orother sorbent tubes to undergo lab GC/MS analysis.If Tenax tubes are to be utilized, special care mustbe taken to avoid contamination. Handling of thetubes should be kept to a minimum, and samplersmust wear nylon or other lint-free gloves. Aftersampling, each tube should be stored in a clean,sealed culture tube; the ends packed with cleanglass wool to protect the sorbent tube frombreakage. The culture tubes should be kept cooland wrapped in aluminum foil to prevent anyphotodegradation of samples (see Section 3.7.4.).

3.3.3 SUMMA Canister

The SUMMA canisters used for soil gas samplinghave a 6-L sample capacity and are certified cleanby GC/MS analysis before being utilized in thefield. After sampling is completed, they are storedand shipped in travel cases.

17


3.4.1 HNU Measurements

A number of factors can affect the response of theHNU PI 101. High humidity can cause lampfogging and decreased sensitivity. This can besignificant when soil moisture levels are high, orwhen a soil gas well is actually in groundwater.High concentrations of methane can cause adownscale deflection of the meter. High and lowtemperature, e l e c t r i c a l f i e l d s , F M r a d i otransmission, and naturally occurring compounds,such as terpenes in wooded areas, will also affectinstrument response.

Other field screening instruments can be affected byinterferences. Consult the manufacturers’ manuals.

3.4.2 Factors Affecting OrganicConcentrations in Soil Gas

Concentrations in soil gas are affected byd isso lu t ion , adsorp t ion , and par t i t ion ing .Partitioning refers to the ratio of component foundin a saturated vapor above an aqueous solution tothe amount in the solution; this can, in theory, becalculated using the Henry’s Law constants.Contaminants can also be adsorbed onto inorganicsoil components or “dissolved” in organiccomponents. These factors can result in a loweringof the partitioning coefficient.

Soil “tightness” or amount of void space in the soilmatrix, will affect the rate of recharging of gas intothe soil gas well.

Existence of a high, or perched, water table, or ofan impermeable underlying layer (such as a claylens or layer of buried slag) may interfere withsampling of the soil gas. Knowledge of site geologyis useful in such situations, and can preventinaccurate sampling.

3.4.3 Soil Probe Clogging

A common problem with this sampling method issoil probe clogging. A clogged probe can beidentified by using an in-line vacuum gauge or bylistening for the sound of the pump laboring. Thisproblem can usually be eliminated by using a wirecable to clear the probe (see procedure #3 inSection 3.7.1).

18

3.4.4 Underground Utilities

Prior to selecting sample locations, an undergroundutility search is recommended. The local utilitycompanies can be contacted and requested to markthe locations of their underground lines. Samplingplans can then be drawn up accordingly. Eachsample location should also be screened with ametal detector or magnetometer to verify that nounderground pipes or drums exist.

EQUIPMENT/APPARATUS

Slam Bar Method

slam bar (one per sampling team)soil gas probes, stainless steel tubing, 1/4-inch O.D., 5 foot lengthflexible wire or cable used for clearing thetubing during insertion into the well“quick connect” fittings to connect samplingprobe tubing, monitoring instruments, andGilian pumps to appropriate fittings onvacuum boxmodeling clayvacuum box for drawing a vacuum aroundTedlar bag for sample collection (one persampling team)Gilian pump Model HFS113A adjusted toapproximately 3.0 L/min (one to two persampling team)l/4-inch Teflon tubing, 2 to 3 foot lengths,for replacement of contaminated samplelineTedlar bags, 1 liter, at least one bag persample pointsoil gas sampling labels, field data sheets,logbook, etc.HNU Model PI 101, or other field airmonitoring devices, (one per samplingteam)ice chest, for carrying equipment and forprotection of samples (two per samplingteam)metal detector or magnetometer, forde tec t ing u n d e r g r o u n d u t i l i t i e s /pipes/drums (one per sampling team)Photovac GC, for field-lab analysis ofbagged samplesSUMMA canisters (plus their shippingc a s e s ) f o r s a m p l e , s t o r a g e a n dtransportation

3.5.2 Power Hammer Method

?

?

?

?

?

3.6

?

?

Bosch demolition hammerl/2inch O.D. steel probes, extensions, andpointsdedicated aluminum sampling pointsTeflon tubing, l/Cinch O.D.“quick connect” fittings to connect samplingprobe tubing, monitoring instruments, andGilian pumps to appropriate fittings onvacuum boxmodeling clayvacuum box for drawing a vacuum aroundTedlar bag for sample collection (one persampling team)Gilian pump Model HFS113A adjusted toapproximately 3.0 L/min (one to two persampling team)l/4-inch Teflon tubing, 2 to 3 foot lengths,for replacement of contaminated samplelineTedlar bags, 1 liter, at least one bag persample pointsoil gas sampling labels, field data sheets,logbook, etc.HNU Model PI 101, or other field airmonitoring devices, (one per samplingteam)ice chest, for carrying equipment and forprotection of samples (two per samplingteam)metal detector or magnetometer, forde tec t ing underground ut i l i t i e s /pipes/drums (one per sampling team)Photovac GC, for field-lab analysis ofbagged samplesSUMMA canisters (plus their shippingcases) for sample, storage andtransportationgenerator with extension cordshigh lift jack assembly for removing probes

REAGENTS

HNU Systems Inc. Calibration Gas forHNU Model PI 101, and/or calibration gasfor other field air monitoring devicesdeionized organic-free water, fordecontaminationm e t h a n o l , H P L C g r a d e , f o rdecontaminationultra-zero grade compressed air, for fieldblanks

? standard gas preparations for Photovac GCcalibration and Tedlar bag spikes

3.7 PROCEDURES

3.7.1 Soil Gas Well Installation

1. Initially, make a hole slightly deeper than thedesired depth. For sampling up to 5 feet, usea 5-foot single piston slam bar. For deeperdepths, use a piston slam bar with threaded 4-foot-long extensions. Other techniques can beused, so long as holes are of narrow diameterand no contamination is introduced.

2. After the hole is made, carefully withdraw theslam bar to prevent collapse of the walls of thehole. Then insert the soil gas probe.

3. It is necessary to prevent plugging of the probe,especially for deeper holes. Place a metal wireor cable, slightly longer than the probe, into theprobe prior to inserting into the hole. Insertthe probe to full depth, then pull it up 3 to 6inches, then clear it by moving the cable up anddown. The cable is removed before sampling.

4. Seal the top of the sample hole at the surfaceagainst ambient air infiltration by usingmodeling clay molded around the probe at thesurface of the hole.

5. If conditions preclude hand installation of thesoil gas wells, the power driven system may beemployed. Use the generator-powereddemolition hammer to drive the probe to thedesired depth (up to 12 feet may be attainedwith extensions). Pull the probe up 1 to 3inches if the retractable point is used. No clayis needed to seal the hole. After sampling,retrieve the probe using the high lift jackassembly.

6. If semi-permanent soil gas wells are required,use the dedicated aluminum probe points.Insert these points into the bottom of thepower-driven probe and attach it to the Teflontubing. Insert the probe as in step 5. Whenthe probe is removed, the point and Teflontube remain in the hole, which may be scaledby backfilling with sand, bentonite, or soil.

3.7.2 Screening with FieldInstruments

The well volume must be evacuated prior tosampling. Connect the Gilian pump, adjustedto 3.0 L/min, to the sample probe using asection of Teflon tubing as a connector. Turnthe pump on, and a vacuum is pulled throughthe probe for approximately 15 seconds. Alonger time is required for sample wells ofgreater depths.

After evacuation, connect the monitoringinstrument(s) to the probe using a Teflonconnector. When the reading is stable, orpeaks, record the reading. For detailedprocedures on HNU field protocol, seeappendix B, and refer to the manufacturer’sinstructions.

Some readings may be above or below therange set on the field instruments. The rangemay be reset, or the response recorded as afigure greater than or less than the range.Consider the recharge rate of the well with soilgas when sampling at a different range setting.

3.7.3 Tedlar Bag Sampling

Follow step 1 in section 3.7.2 to evacuate wellvolume. If air monitoring instrument screeningwas performed prior to sampling, evacuation isnot necessary.

Use the vacuum box and sampling train (Figure3 in Appendix A) to take the sample. Thesampling train is designed to minimize theintroduction of contaminants and losses due toadsorption. All wetted parts are either Teflonor stainless steel. The vacuum is drawnindirectly to avoid contamination from samplepumps.

Place the Tedlar bag inside the vacuum box,and attach it to the sampling port. Attach thesample probe to the sampling port via Teflontubing and a “quick connect” fitting.

Draw a vacuum around the outside of the bag,using a Gilian pump connected to the vacuumbox evacuation port, via Tygon tubing and a“quick connect” fitting. The vacuum causes thebag to inflate, drawing the sample.

5. Break the vacuum by removing the Tygon linefrom the pump. Remove the bagged samplefrom the box and close valve. Label bag,record data on data sheets or in logbooks.Record the date, time, sample location ID, andthe HNU, or other instrument reading(s) onsample bag label.

CAUTION: Labels should not be pasted directlyonto the bags, nor should bags be labeled directlyusing a marker or pen. Inks and adhesive maydiffuse through the bag material, contaminating thesample. Place labels on the edge of the bags, or tiethe labels to the metal eyelets provided on the bags.Markers with inks containing volatile organics (i.e.,permanent ink markers) should not be used.

3.7.4 Tenax Tube Sampling

Samples collected in Tedlar bags may be sorbedonto Tenax tubes for further analysis by GC/MS.

Additional Apparatus

?? Syringe with a luer-lock tip capable ofdrawing a soil gas or air sample from aTedlar bag onto a Tenax/CMS sorbenttube. The syringe capacity is dependentupon the volume of sample being drawnonto the sorbent tube.

?? Adapters for fitting the sorbent tubebetween the Tedlar bag and the samplingsyringe. The adapter attaching the Tedlarbag to the sorbent tube consists of areducing union (l/Cinch to l/16-inch O.D.-- Swagelok cat. # SS-400-6-ILV orequivalent) with a length of l/4 inch O.D.Teflon tubing replacing the nut on the 1/6-inch (Tedlar bag) side. A l/Cinch I.D.silicone O-ring replaces the ferrules in thenut on the l/Cinch (sorbent tube) side ofthe union.

The adapter attaching the sampling syringeto the sorbent tube consists of a reducingunion (l/Cinch to l/16-inch O.D. --Swagelok Cat. # SS-4OO-6-ILV orequivalent) with a l/Cinch I.D. siliconeO-ring replacing the ferrules in the nut onthe l/4 inch (sorbent tube) side and theneedle of a luer-lock syringe needleinserted into the l/16-inch side (held inplace with a l/16-inch ferrule). The

20

luer-lock end of the needle can be attachedto the sampling syringe. It is useful to havea luer-lock on/off valve situated betweenthe syringe and the needle.

?? Two-stage glass sampling cartridge (1/4-inch O.D. x l/&inch I.D. x 5 1/8 inch)contained in a flame-sealed tube(manufactured by Supelco CustomTenax/Spherocarb Tubes or equivalent)containing two sorbent sections retained byglass wool:

Front section: 150 mg of Tenax-GCBack section: 150 mg of CMS(Carbonized Molecular Sieve)

Sorbent tubes may also be prepared in thelab and stored in either Teflon-cappedculture tubes or stainless steel tubecontainers. Sorbent tubes stored in thismanner should not be kept more than 2weeks without reconditioning. (See SOP#2052 for Tenax/CMS sorbent tubepreparation).

?? Teflon-capped culture tubes or stainlesssteel tube containers for sorbent tubestorage. These containers should beconditioned by baking at 120°C for at least2 hours. The culture tubes should containa glass wool plug to prevent sorbent tubebreakage during transport. Reconditioningof the containers should occur betweenusage or after extended periods of disuse(i.e., 2 weeks or more).

?? Nylon gloves or lint-free cloth. (HewlettPackard Part # 8650-0030 or equivalent.)

Sample Collection

1. Handle sorbent tubes with care, using nylongloves (or other lint-free material) to avoidcontamination.

2. Immediately before sampling, break one end ofthe sealed tube and remove the Tenaxcartridge. For in-house prepared tubes, removecartridge from its container.

3. Connect the valve on the Tedlar bag to thesorbent tube adapter. Connect the sorbent tubeto the sorbent tube adapter with the Tenax

4.

8.

9.

(white granular) side of the tube facing theTedlar bag.

Connect the sampling syringe assembly to theCMS (black) side of the sorbent tube. Fittingson the adapters should be very tight.

Open the valve on the Tedlar bag.

Open the on/off valve of the sampling syringe.

Draw a predetermined volume of sample ontothe sorbent tube. (This may require closing thesyringe valve, emptying the syringe and thenrepeating the procedure, depending upon thesyringe capacity and volume of samplerequired.)

After sampling, remove the tube from thesampling train with gloves or a clean cloth. Donot label or write on the Tenax/CMS tube.

Place the sorbent tube in a conditionedstainless steel tube holder or culture tube.Culture tube caps should be sealed with Teflontape.

Sample Labeling

Each sample tube container (not tube) must belabeled with the site name, sample station number,sample date, and sample volume.

Chain of custody forms must accompany all samplesto the laboratory.

Quality Assurance

Before field use, a QA check should be performedon each batch of sorbent tubes by analyzing a tubewith thermal desorption/cryogenic trappingGC/MS.

At least one blank sample must be submitted witheach set of samples collected at a site. This tripblank must be treated the same as the sample tubesexcept no sample will be drawn through the tube.

Sample tubes should be stored out of UV light (i.e.,sunlight) and kept on ice until analysis.

Samples should be taken in duplicate, whenpossible.

31

3.7.5 SUMMA Canister Sampling

1. Follow item 1 in step 3.7.2 to evacuate wellvolume. If HNU analysis was performed priorto taking a sample, evacuation is not necessary.

2. Attach a certified clean, evacuated 6-LSUMMA canister via the l/4-inch Teflontubing.

3. Open the valve on SUMMA canister. The soilgas sample is drawn into the canister bypressure equilibration. The approximatesampling time for a 6-L canister is 20 minutes.

4. Site name, sample location, number, and datemust be recorded on a chain of custody formand on a blank tag attached to the canister.

3.8 CALCULATIONS

3.8.1 Field Screening Instruments 3.9.4 Sample Train Contamination

Instrument readings are usually read directly fromthe meter. In some cases, the background level atthe soil gas station may be subtracted:

Final Reading = Sample Reading -Background

3.8.2 Photovac GC Analysis

Calculations used to determine concentrations ofindividual components by Photovac GC analysis arebeyond the scope of this SOP and are covered inERT SOP #2109, Photovac GC Analysis for Soil,Water and Air/Soil Gas.


3.9.1 Field Instrument Calibration

Consult the manufacturers’ manuals for correct useand calibration of all instrumentation. The HNUshould be calibrated at least once a day.

3.9.2 Gilian Model HFS113A AirSampling Pump Calibration

Flow should be set at approximately 3.0 L/min;

accurate flow adjustment is not necessary. Pumpsshould be calibrated prior to bringing into the field.

3.9.3 Sample Probe Contamination

Sample probe contamination is checked betweeneach sample by drawing ambient air through theprobe via a Gilian pump and checking the responseof the HNU PI 101. If HNU readings are higherthan background, replacement or decontaminationis necessary.

Sample probes may be decontaminated simply bydrawing ambient air through the probe until theHNU reading is at background. More persistentcontamination can be washed out using methanoland water, then air drying. Having more than oneprobe per sample team will reduce lag timesbetween sample stations while probes aredecontaminated.

The Teflon line forming the sample train from theprobe to the Tedlar bag should be changed on adaily basis. If visible contamination (soil or water)is drawn into the sampling train, it should bechanged immediately. When sampling in highlycontaminated areas, the sampling train should bepurged with ambient air, via a Gilian pump, forapproximately 30 seconds between each sample.After purging, the sampling train can be checkedusing an HNU, or other field monitoring device, toestablish the cleanliness of the Teflon line.

3.9.5 Field Blank

Each cooler containing samples should also containone Tedlar bag of ultra-zero grade air, acting as afield blank. The field blank should accompany thesamples in the field (while being collected) andwhen they are delivered for analysis. A fresh blankmust be provided to be placed in the empty coolerpending additional sample collection. One new fieldblank per cooler of samples is required. A chain ofcustody form must accompany each cooler ofsamples and should include the blank that isdedicated to that group of samples.

3.9.6 Trip Standard

Each cooler containing samples should contain aTedlar bag of standard gas to calibrate the

22

analytical instruments (Photovac GC, etc.). Thistrip standard will be used to determine any changesin concentrations of the target compounds duringthe course of the sampling day (e.g., migrationthrough the sample bag , degrada t ion , o radsorption). A fresh trip standard must be providedand placed in each cooler pending additional samplecollection. A chain of custody form shouldaccompany each cooler of samples and shouldinclude the trip standard that is dedicated to thatgroup of samples.

3.9.7 Tedlar Bag Check

Prior to use, one bag should be removed from eachlot (case of 100) of Tedlar bags to be used forsampling and checked for possible contamination asfollows: the test bag should be tilled with ultra-zerograde air; a sample should be drawn from the bagand analyzed via Photovac GC or whatever methodis to be used for sample analysis. This procedurewill ensure sample container cleanliness prior to thestart of the sampling effort.

Spikes

A Tedlar bag spike and Tenax tube spike may bedesirable in situations where high concentrations ofcontaminants other than the target compounds arefound to exist (landfills, etc.). The additional levelof QA/QC attained by this practice can be useful indetermining the effects of interferences caused bythese non-target compounds. SUMMA canisterscontaining samples are not spiked.


For each target compound, the level ofconcentration found in the sample must be greaterthan three times the level (for that compound)found in the field blank which accompanied thatsample to be considered valid. The same criteriaapply to target compounds detected in the Tedlarbag pre-sampling contamination check.

3.11 HEALTH AND SAFETY3.9.8 SUMMA Canister Check

From each lot of four cleaned SUMMA canisters,one is to be removed for a GC/MS certificationcheck. If the canister passes certification, then it isre-evacuated and all four canisters from that lot areavailable for sampling.

If the chosen canister is contaminated, then theentire lot of four SUMMA canisters must berecleaned, and a single canister is re-analyzed byGC/MS for certification.

3.9.9 Options

Duplicate Samples

A minimum of 5% of all samples should becollected in duplicate (i.e., if a total of 100 samplesarc to be collected, five samples should beduplicated). In choosing which samples toduplicate, the following criterion applies: if, afterfilling the first Tedlar bag, and, evacuating the wellfor 15 seconds, the second HNU (or other fieldmonitoring device being used) reading matches oris close to (within 50%) the first reading, aduplicate sample may be taken.

Because the sample i s be ing d rawn f romunderground, and no contamination is introducedinto the breathing zone, soil gas sampling usuallyoccurs in Level D, unless the sampling location iswithin the hot zone of a site, which requires LevelB or Level C protection. However, to ensure thatthe proper level of protection is utilized, constantlymonitor the ambient air using the HNU PI 101 toobtain background readings during the samplingprocedure. As long as the levels in ambient air donot rise above background, no upgrade of the levelof protection is needed.

Also, perform an underground utility search prior tosampling (see section 3.4.4). When working withpotentially hazardous materials, follow U.S. EPA,OSHA, and specific health and safety procedures.

23

4.0 MONITORING WELL INSTALLATION: SOP #2150


The purpose of this Standard Operating Procedure(SOP) is to provide an overview of the methodsused for monitoring well installation. Monitoringwell installation creates a permanent access for thecollection of samples to determine groundwaterquality and the hydrogeologic properties of theaquifer in which the contaminants exist. Such wellsshould not alter the medium which is beingmonitored.

The most commonly used drilling methods are: (1)hollow-stem augers, (2) cable tool drills, and (3)rotary drills. Rotary drilling can be divided into amud rotary or air rotary method.

4.2 METHOD SUMMARY

There is no ideal monitoring well installationmethod for all conditions; therefore, hydrogeologicconditions at the site and project objectives must beconsidered before deciding which drilling method touse.

4.2.1 Hollow-Stem Augering

Hollow-stem augering is fast and relatively lessexpensive than cable tool or rotary drilling methods.It is possible to drill several hundred feet ofborehole per day in unconsolidated formations.

4.2.2 Cable Tool Drilling

Cable tool drilling method involves lifting anddropping a heavy, solid chisel-shaped bit, suspendedon a steel cable. This bit pounds a hole throughsoil and rock. Temporary steel casing is used whiledrilling to keep the hole open and to isolate strata.The temporary casing is equipped with a drive shoe,which is attached to the lower end, and which aidsthe advancement of the casing by drilling out aslightly larger diameter borehole than the holemade by the drill bit alone.

Water is sometimes used when drilling above thesaturated zone to reduce dust and to form a slurrywith the loosened material. This facilitates removalof cuttings using a bailer or a sand pump. Potable

water or distilled/deionized water should be used toprevent the introduction of contamination into theborehole.

4.2.3 Rotary Drilling

Mud Rotary Method

In the mud rotary method, the borehole is advancedby rapid rotation of the drill bit, which cuts andbreaks the material at the bottom of the hole intosmaller pieces. Cuttings are removed by pumpingdrilling fluid (water, or water mixed with bentonite)down through the drill rods and bit, and up thearmulus between the borehole and the drill rods.The drilling fluid also serves to cool the drill bit andprevent the borehole from collapsing inunconsolidated formations.

Air Rotary Method

The air rotary method is the same as the mudrotary except that compressed air is pumped downthe drill rods and returns with the drill cuttings upthrough the annulus. Air rotary method is generallylimited to consolidated and semi-consolidatedformations. Casing is sometimes used to preventcavings in semi-consolidated formations. The airmust be filtered to prevent introduction ofcontamination into the borehole.


Often, a primary object of the drilling program is toobtain representative lithologic or environmentalsamples. Lithologic samples are taken in order todetermine the geologic or hydrogeologic regime ata site. The most common techniques for retrievinglithologic samples in unconsolidated formations aredescribed below.

?? Split spoon sampling, carried outcontinuously or at discrete intervals duringdrilling, is used to make a field descriptionof the sample and create a log of eachboring.

25

?? Shelby tube sampling, is used when anundisturbed sample is required from clayeyor silty soils, especially for geotechnicalevaluation or chemical analysis.

? Cuttings description is used when a generallithologic description and approximatedepths are sufficient.

The most common techniques for retrievinglithologic sampling in consolidated formations aredescribed below.

? Rock coring is carried out continuously orat discrete intervals during drilling andenables the geologist to write a fielddescription of the sample, create a log ofeach boring, and map occurrences andorientation of fractures.

? Cuttings description is used when a generallithologic description and approximatedepths are sufficient.


Table 3 on page 27 displays the advantages anddisadvantages of the various drilling techniques.

4.5 EQUIPMENT/APPARATUS

The drilling contractor will provide all operationalequipment for the drilling program which isoutlined. The geologist should bring:

• well log sheets? metal case (container for well logs)• ruler?? depth sounder? water level indicator? all required health and safety gear? sample collection jars?? trowels? description aids (Munsell, grain size charts,

etc.)

4.6 REAGENTS

No chemical reagents are used in this procedure.Decontamination of drilling equipment should

follow ERT SOP #2006, Sampling EquipmentDecontamination and the site-specific work plan.

4.7 PROCEDURES

4.7.1 Preparation

The planning, selection and implementation of anymonitoring well installation program should includethe following steps.

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

Review existing data on site geology andhydrogeology including publications, air photos,water quality data, and existing maps. Thesemay be obtained from local, state, or federalagencies.

Visit the site to observe field geology andpotential access problems for drill rig, toestablish water supply, and drill equipment andmaterials storage area.

Prepare site safety plan.

Define project objectives; select drilling, welldevelopment, and sampling methods.

Select well construction materials including wellconstruction specifications (i.e., casing andscreen materials, casing and screen diameter,screen length and screen interval, filter packand screen size).

D e t e r m i n e n e e d f o r c o n t a i n i n g d r i l lcuttings/fluids and their disposal.

Prepare work plan including all of the above.

Prepare and execute the drilling contract.

Implement the drilling program.

Prepare the final report, including backgrounddata, project objective, field procedure, wellconstruction data including well logs and wellconstruction.

All drilling and well installation programs must beplanned and supervised by a professionalgeologist/hydrogeologist.


1. Prior to the mobilization of the drill rig,

26

Table 3: Advantages and Disadvantages of Various Drilling Techniques

Drilling Type

Auger

Advantages Disadvantages

?? Allows sampling from different strata ??Very slow or impossible in coarseduring drilling. materials such as cobbles and boulders.

?? Less potential for cross-contamination ? Cannot drill hard rock formations and isbetween strata than in other generally not suited for wells deeper thantechniques. 100 feet.

??Large diameter borehole may be ??Not good in caving formations.drilled for multiple-well completion. ??Potential for disturbing large volume of

??Less well development is generally needed subsurface materials around the borehole;than in mud rotary because of the therefore affecting local permeabilitiesrelatively large diameter borehole, the and creating annular channels forability to emplace a large and effective contaminant movement between differentgravel pack, and because no drilling fluids strata.are introduced into the borehole.

Cable Tool ??Allows for easy and accurate detection ofthe water table.

??Driven casing seals off formation,minimizing the threat of cross-

??Extremely slow rate of drilling.??Can lose casing in deep wells.

contamination in pollution investigation.??Especially successful for drilling in glacial

till.

Mud Rotary ??Quite fast, more than 100 feet of borehole ??Potential cross-contamination of strataadvancement per day is possible. exposed to the circulating drilling fluid

??Geophysical logs such as resistivity (which during drilling.must be run in an uncased borehole) can ??Difficulty in removing mud residuesbe run before well construction. during well development.

??Drilling mud may alter the groundwaterchemistry by binding metals, sorbingorganic compounds and by altering pH,cation exchange capacity and chemicaloxidation demand of native fluids.

??Drilling mud may change localpermeability of the formation.

Air Rotary ??Like mud rotary method, more than 100feet of borehole advancement a day ispossible.

?? Sampling different strata during drilling ispossible if temporary casing is advanced.

?? In contaminated formations, the use ofhigh pressure air may pose a significanthazard to the drill crew due to rapidtransport of contaminated material up theborehole during drilling.

? Introduction of air to ground water couldreduce concentration of volatile organiccompounds locally.

27

thoroughly decontaminate the rig and allassociated equipment to remove all oil, grease,mud, etc.

2. Before drilling each boring, steam-clean andrinse all the “down-the-hole” drill equipmentwith potable water to minimize cross-contamination. Special attention should begiven to the thread section of the casings, andto the drill rods. All drilling equipment shouldbe steam-cleaned at completion of the projectto ensure that no contamination is transportedto or from the sampling site.

2.

3. Record lithologic descriptions and all fieldmeasurements and comments on the well logform (Appendix C). Include well constructiondiagrams on the well log form for each wellinstalled. At a minimum, the well constructioninformation should show depth from surfacegrade, the bottom of the boring, the screenedinterval, casing material, casing diameter, gravelpack location, grout seal and height of riserpipe above the ground. Also record the actualcompositions of the grout and seal on the welllog form.

3.

4.7.3 Well Construction

The most commonly used casing materials includestainless steel, polyvinyl chloride (PVC) and Teflon.Monitoring wells are constructed with casings andmaterials that are resistant to the subsurfaceenvironment. The selection of well constructionmaterial is based on the material’s long-terminteraction with the contaminated groundwater.Construction materials should not cause ananalytical bias in the interpretation of the chemicalanalysis of the water samples.

4.

Well casing material should also be judged from astructural standpoint. Material should be rigid andnonporous, with a low surface-area-to-water ratio inthe wellbore relative to the formation materials(U.S. EPA, 1987).

1. Fill the annular space between the well screenand the boring with a uniform gravel/sand packto serve as a filter media. For wells deeperthan approx imate ly 50 fee t , o r whenrecommended by the site geologist, emplace thesand pack using a tremie pipe (normallyconsisting of a 1.25inch PVC or steel pipe).Pump sand slurry composed of sand and

potable water through the tremie pipe into theannulus throughout the entire screened interval,and over the top of the screen. It is necessaryto pump sufficient sand/gravel slurry to coverthe screen after the sand/gravel pack hassettled and become dense.

Determine the depth of the top of the sandusing the tremie pipe, thus verifying thethickness of the sand pack. Add more sand tobring the top of the sand pack to approximately2-3 feet above the top of the well screen.Under no circumstances should the sand packextend into any aquifer other than the one tobe monitored. In most cases, the well designcan be modified to allow for a sufficient sandpack without threat of crossflow betweenproducing zones through the sand pack.

In materials that will not maintain an openhole, withdraw the temporary or outer casinggradually during placement of sand pack/groutto the extent practical.

For example, after filling 2 feet with sand pack,the outer casing should be withdrawn 2 feet.Th is s t ep o f p lac ing more g rave l andwithdrawing the outer casing should berepeated until the level of the sand pack isapproximately 3 feet above the top of the wellscreen. This ensures that there is no locking ofthe permanent (inner) casing in the outercasing.

Emplace a bentonite seal, composed of pellets,between the sand pack and grout to preventinfiltration of cement into the filter pack andthe well screen.

These pellets should have a minimum purity of90% montmorillonite clay, and a minimum drybulk density of 75 lb/ft3 for ½ inch pellets, asprovided by American Colloid, or equivalent.Bentonite pellets shall be poured directly downthe annulus.

Care must be taken to avoid introducing pelletsinto the well bore. A cap placed over the topof the well casing before pouring the bentonitepellets from the bucket will prevent this. Toensure even application, pour the pellets fromdifferent points around the casing. To avoidbridging of pellets, they should not beintroduced at a rate faster than they can settle.A tremie pipe may be used to redistribute and

28

level out the top of the seal,

5. If using a slurry of bentonite as an annular seal,prepare it by mixing powdered or granularbentonite with potable water. The slurry mustbe of sufficiently high specific gravity andviscosity to prevent its displacement by thegrout to be emplaced above it. As aprecaution, regardless of depth, and dependingon fluid viscosity, add a few handfuls ofbentonite pellets to solidify the bentonite slurrysurface.

6. Place a mixture of cement and bentonite groutfrom the top of the bentonite seal to theground surface.

Only Type I or II cement without acceleratoradditives may be used. An approved source ofpotable water must be used for mixing groutingmaterials. The following mixes are acceptable:

? Neat cement, a maximum of 6 gallons ofwater per 94-pound bag of cement

?? Granular bentonite, 1.5 pounds ofbentonite per 1 gallon of water

of grout from dropping below the bottom ofthe casing.

9. Additional grout may be added to compensatefor the removal of the temporary casing andthe tremie pipe to ensure that the top of thegrout is at or above ground surface.

10. Place the protective casing. Protective casingsshould be installed around all monitoring wells.Exceptions are on a case-by-case basis. Theminimum elements in the protection designinclude:

? A protective steel cap to keep precipitationout of the protective casing, secured to thecasing by padlocks.

?

?? Cement-bentonite, 5 pounds of purebentonite per 94-pound bag of cement with7-8 gallons of water; 13-14 pounds weight,if dry mixed

? Cement-bentonite, 6 to 8 pounds of purebentonite per 94-pound bag of cement with8-10 gallons of water, if water mixed

? A 5-foot-minimum length of black iron orgalvanized pipe, extending about 1.5 to 3feet above the ground surface, and set incement grout. The pipe diameter shouldbe 8 inches for 4-inch wells, and 6 inchesfor 2-inch wells (depending on approvedborehole size). A 0.5-inch drain hole nearground level is permitted.

?? Non-expandable cement, mixed at 7.5gallons of water to l/2 teaspoon ofaluminum hydroxide, 94 pounds of neatcement (Type I) and 4 pounds of bentonite

? Non-expandable cement, mixed at 7 gallonsof water to l/2 teaspoon of aluminumhydroxide, 94 pounds of neat cement (TypeI and Type II)

7. Pump grout through a tremie pipe to thebottom of the open annulus until undilutedgrout flows from the annulus at the groundsurface.

8. In materials that will not maintain an openhole, the temporary steel casing should bewithdrawn in a manner that prevents the level

The installation of guard posts in additionto the protective casing, in areas wherevehicular traffic may pose a hazard. Theseguard posts consist of 3-inch diameter steelposts or tee-bar driven steel posts. Groupsof three are radially located 4 feet aroundeach well 2 feet below and 4 feet aboveground surface, with flagging in areas ofhigh vegetation. Each post is cemented in-place.

?? A flush mount of protective casing mayalso be used in areas of high traffic orwhere access to other areas would belimited by a well with stickup.

After the grout sets (about 48 hours), fill anydepression due to settlement with a grout mixsimilar to that described above.

4.0 CALCULATIONS

To maintain an open borehole using sand or waterrotary drilling, the drilling fluid must exert apressure greater than the formation pore pressure.Typical pore pressure for an unconfined aquifer is

29

0.433 psi/ft and for a confined aquifer is 0.465psi/ft.

The calculation for determining the hydrostaticpressure of the drilling fluid is:

Hydrostatic Pressure (psi) = Fluid Density(lb/gal) x Height of Fluid Column (ft) x 0.052

The minimum grout volume necessary to grout awell can be calculated using:

Grout Vol (ft3) = Vol of Borehole (f3) -Vol of Casing (ft3)

= L ( rb2 - rc

2)

where:

rB = radius of boring (ft)rc = radius of casing (ft)L = length of borehole to be grouted (ft)


There are no specific quality assurance activitieswhich apply to the implementation of theseprocedures.

30

However, the following general QA proceduresapply:

• All data must be documented on standardwell completion forms, field data sheets orwithin field/site logbooks.

All instrumentation must be operated inaccordance with operating instructions assupplied by the manufacturer, unlessotherwise specified in the work plan.Equipment checkout and calibrationactivities must o c c u r p r i o r t osampling/operation and they must bedocumented.




When working with potentially hazardous materials,follow U.S. EPA, OSHA, and specific health andsafety procedures.

5.0 WATER LEVEL MEASUREMENT: SOP #2151


The purpose of this Standard Operating Procedure(SOP) is to set guidelines for the determination ofthe depth to water in an open borehole, casedborehole, monitoring well or piezometer.

Generally, water level measurements fromboreholes, piezometers, or monitoring wells areused to construct water table or potentiometricsurface maps. Therefore, all water levelmeasurements at a given site should be collectedwithin a 24-hour period. Certain situations maynecessitate that all water level measurements betaken within a shorter time interval. Thesesituations may include:

?

the magnitude of the observed changesbetween wells appears too large

atmospheric pressure changes

aquifers which are tidally influenced

aquifers affected by river stage,impoundments, and/or unlined ditches

aquifers stressed by intermittent pumpingof production wells

? aquifers being actively recharged due toprecipitation events

5.2 METHOD SUMMARY

A survey mark should be placed on the casing foruse as a reference point for measurement. Manytimes the lip of the riser pipe is not flat. Anothermeasuring reference should be located on the groutapron. The measuring point should be documentedin the site logbook and on the groundwater leveldata form (see Appendix C).

Water levels in piezometers and monitoring wellsshould be allowed to stabilize for a minimum of 24hours after well construction and development, priorto measurement. In low yield situations, recoverymay take longer.

31

Working with decontaminated equipment, proceedfrom the least to the most contaminated wells.Open the well and monitor headspace with theappropriate monitoring instrument to determine thepresence of volatile organic compounds. Lower thewater level measurement device into the well untilwater surface or bottom of casing is encountered.Measure distance from water surface to thereference point on the well casing and record in thesite logbook and/or groundwater level data form.Remove all downhole equipment, decontaminate asnecessary, and replace well casing cap.

5.3 SAMPLE PRESERVATION,CONTAINERS, HANDLING ANDSTORAGE


5.4

•

?

?

?

INTERFERENCES ANDPOTENTIAL PROBLEMS

The chalk used oncontaminate the well.

steel tape may

Cascading water may obscure the watermark or cause it to be inaccurate.

Many types of electric sounders use metalindicators at 5-foot intervals around aconducting wire. These intervals should bechecked with a surveyor’s tape to ensureaccuracy.

If there is oil present on the water, it caninsulate the contacts of the probe on anelectric sounder or give false readings dueto thickness of the oil. Determining thethickness and density of the oil layer maybe warranted, in order to determine thecorrect water level.

Turbulence in the well and/or cascadingwater can make water level determinationdifficult with either an electric sounder orsteel tape.

?? An airline measures drawdown duringpumping. It is only accurate to 0.5 footunless it is calibrated for various“drawdowns”.


There are a number of devices which can be used tomeasure water levels, such as steel tape or airlines.The device should be adequate to attain an accuracyof 0.01 feet.

The following equipment is needed to measurewater levels:

? air monitoring equipment? water level measurement device? electronic water level indicator? metal tape measure? airline? steel tape? chalk? ruler? notebook? paper towels? decontamination solution and equipment? groundwater level data forms

5.6 REAGENTS

No chemical reagents are used in this procedure,with the exception of decontamination solutions.Where decontamination of equipment is required,refer to ERT SOP #2006, Sampling EquipmentDecontamination and the site-specific work plan.

5.7 PROCEDURES

57.1 Preparation

1. Determine the extent of the sampling effort, thesampling methods to be employed, and whichequipment and supplies are needed.

2. Obtain necessary sampling and monitoringequipment.

3. Decontaminate or preclean equipment, andensure that it is in working order.

4. Prepare scheduling and coordinate with staff,

clients, and regulatory agency, if appropriate.

5. Perform a general site survey prior to site entryin accordance with the site-specific health andsafety plan.

6. Identify and mark all sampling locations.

5.7.2 Procedures

1. Make sure water level measuring equipment isin good operating condition.

2. If possible and where applicable, start at thosewells that are least contaminated and proceedto those wells that are most contaminated.

3. Clean all equipment entering the well by thefollowing decontamination procedure:

Triple rinse equipment with deionizedwater.

Wash equipment with an Alconox solutionfollowed by a deionized water rinse.

Rinse with an approved solvent (e.g.,methanol, isopropyl alcohol, acetone) asper the work plan, if organic contaminationis suspected.

Place equipment on clean surface such asa Teflon or polyethylene sheet.

4. Remove locking well cap, note location, time ofday, and date in site notebook or anappropriate groundwater level data form.

5. Remove well casing cap.

6. If required by site-specific condition, monitorheadspace of well with PID or PID todetermine presence of volatile organiccompounds and record in site logbook.

7. Lower electric water level measuring device orequivalent (i.e., permanently installedtranducers or airline) into the well until watersurface is encountered.

8. Measure the distance from the water surface tothe reference measuring point on the wellcasing or protective barrier post and record inthe field logbook. In addition, note that the

32

water level measurement was from the top ofthe steel casing, top of the PVC riser pipe,from the ground surface, or from some otherposition on the well head.

9. The groundwater level data form in AppendixC should be completed as follows:

• site name

? logger name: person taking field notes

? date: the date when the water levels arebeing measured

?? location: monitor well number andphysical location

? time: the military time at which the waterlevel measurement was recorded

?? depth to water: the wa te r l eve lmeasurement in feet, or in tenths orhundreds of feet, depending on theequipment used

? comments: any information the fieldpersonnel feels to be applicable

• measuring point: marked measuring pointon PVC riser pipe, protective steel casingor concrete pad surrounding well casingfrom which all water level measurementsfor individual wells should be measured.This provides consistency in future waterlevel measurements.

10. Measure total depth of well (at least twice toconfirm measurement) and record in sitenotebook or on log form.

11. Remove all downhole equipment, replace wellcasing cap and lock steel caps.

12. Rinse all downhole equipment and store fortransport to next well.

13. Note any physical changes such as erosion orcracks in protective concrete pad or variation intotal depth of well in field notebook and onfield data sheets.

14. Decontaminate all equipment as outlined inStep 3 above.

5.8 CALCULATIONS

To determine groundwater elevation above meansea level, use the following equation:

Ew = E-D

where:

E w = Elevation of water above mean sealevel

E = Elevation above sea level at pointof measurement

D = Depth to water


The following general quality assurance proceduresapply:

• All data must be documented on standardchain of custody forms, field data sheets orwithin personal/site logbooks.

?

5.10

All instrumentation must be operated inaccordance with operating instructions assupplied by the manufacturer, unlessotherwise specified in the work plan.Equipment checkout and calibrationactivities must occur p r i o r t osampling/operation, and they must bedocumented.

Each well should be tested at least twice inorder to compare results.

DATA VALIDATION




3 3

6.0 WELL DEVELOPMENT: SOP #2156


The purpose of monitoring well development is toensure removal of fines from the vicinity of the wellscreen. This allows free flow of water from theformation into the well and also reduces theturbidity of the water during sampling events. Themost common well development methods are:surging, jetting, and overpumping.

Surging involves raising and lowering a surge blockor surge plunger inside the well. The resultingmotion surges water into the formation and loosenssediment to be pulled from the formation into thewell. Occasionally, sediment must be removed fromthe well with a sand bailer to prevent sand lockingof the surge block. This method may cause thesand pack around the screen to be displaced to adegree that damages its value as a filtering medium.For example, channels or voids may form near thescreen if the filter pack sloughs away during surging(Keely and Boateng, 1987).

Jetting involves lowering a small diameter pipe intothe well to a few feet above the well screen, andinjecting water or air through the pipe underpressure so that sediments at the bottom aregeysered out the top of the well. It is important notto jet air or water directly across the screen. Thismay cause fines in the well to be driven into theentrance of the screen openings thereby causingblockages.

Overpumping involves pumping at a rate rapidenough to draw the water level in the well as low aspossible, and allowing it to recharge. This processis repeated until sediment-free water is produced.Overpumping is not as vigorous as surging andjetting and is probably the most desirable formonitoring well development.

6.2 METHOD SUMMARY

Development of a well should occur as soon aspractical after installation, but not sooner than 48hours after grouting is completed, if a rigorous welldevelopment is being used. If a less rigorousmethod, such as bailing, is used for development, itmay be initiated shortly after installation. The main

concern is that the method being used fordevelopment does not interfere with allowing thegrout to set.

Open the monitoring well, take initial measurements(e.g. head space air monitoring readings, waterlevel, well depth, pH, temperature, and specificconductivity) and record results in the site logbook.Develop the well by the appropriate method (i.e.,overpumping jetting, or surging) to accommodatesite conditions and project requirements. Continueuntil the developed water is clear and free ofsediment. Containerize all discharge water fromknown or suspected contaminated areas. Recordfinal measurements in the logbook. Decontaminateequipment as appropriate prior to use in the nextwell.


This section is not applicable to this StandardOperating Procedure (SOP).


The following interferences or problems may occurduring well development:

? The possibility of disturbing the filter packincreases with surging and jetting welldevelopment methods.

? The introduction of external water or air byjetting may alter the hydrochemistry of theaquifer.


The type of equipment used for well development isdependent on the diameter of the well. Forexample, submersible pumps cannot be used forwell development unless the wells are 4 inches orgreater in d iamete r , because the smal les t

35

submersible pump has a 3 l/4 inch O.D.

In general, the well should be developed shortlyafter it is drilled. Most drilling rigs have aircompressors or pumps that may be used for thedevelopment process.

6.6 REAGENTS

No chemical reagents are used in this procedureexcept for decontamination solutions. Forguidelines on equipment decontamination, refer toE R T S O P # 2 0 0 6 , Sampling EquipmentDecontamination and the site-specific work plan.

6.7 PROCEDURES

6.7.1 Preparation

Coordinate site access and obtain keys to themonitoring well security cap locks.

Obtain information on each well to bedeveloped (i.e., drilling, method, well diameter,depth, screened interval, anticipatedcontaminants, etc.).

Obtain a water level meter, air monitoringequipment, materials for decontamination, pHand electrical conductivity m e t e r s , athermometer, and a stopwatch.

Assemble containers for temporary storage ofwater produced during well development.Containers must be structurally sound,compatible with anticipated contaminants, andeasy to manage in the field. The use oftruck-mounted tanks may be necessary in somecases; alternately, a portable water treatmentunit (e.g. activated carbon) may be used todecontaminate the purge water.

6.7.2 Operation

The development should be performed as soon aspractical after the well is installed, but no soonerthan 48 hours after grouting is completed.Dispersing agents, acids, or disinfectants should notbe used to enhance development of the well.

1. Assemble necessary equipment on a plasticsheet around the well.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

Record pertinent information in field logbook(personnel, time, location ID, etc.).

Open monitoring well, and take air monitoringreadings at the top of casing and in thebreathing zone as appropriate.

Measure depth to water and the total depth ofthe monitoring well from the same datumpoint.

Measure the initial pH, temperature, andspecific conductivity of the water and record inthe logbook.

Develop the well until the water is clear andappears to be free of sediment. Note the initialcolor, clarity and odor of the water.

All water produced by development incontaminated or suspected contaminated areasmust be containerized or treated. Clearly labeleach container with the location ID.Determination of the appropriate disposalmethod will be based on the fast round ofanalytical results from each well.

No water should be added to the well to assistdevelopment without prior approval by the sitegeologist. If a well cannot be cleaned of mudto produce formation water because the aquiferyields insufficient water, small amounts ofpotable water may be injected to clean up thispoorly yielding well. This may be done bydumping in buckets of water. When most ofthe mud is out, continue development withformation water only. It is essential that atleast live times the amount of water injectedmust be produced back from the well in orderto ensure that all injected water is removedfrom the formation.

Note the final color, clarity and odor of thewater.

Measure the final pH, temperature and specificconductance of the water and record in thefield logbook.

Record the following data in the field logbook:

? well designation (location ID)? date(s) of well installation? date(s) and time of well development? static water level before and after

36

development V = nr 2(cf) [Equation 2]?? quantity of water removed and time of

removal?? type and size/capacity of pump and/or

bailer used? description of well development techniques

used

where:V = volume in gallons per linear footn = Pir =cf =

radius of monitoring well (feet)conversion factor (7.48 gal/ft3)


1. Decontaminate all equipment.

2. Store containers of purge water producedduring development in a safe and secure area.

3. After the first round of analytical results havebeen received, determine and implement theappropriate purge water disposal method.

6.8 CALCULATIONS

There are no calculations necessary to implementthis procedure. However, if it is necessary tocalculate the volume of the well, utilize thefollowing equation:

Well volume = nr2h(cf) [Equation 1]

Monitoring wells are typically 2 inches, 3 inches, 4inches, or 6 inches in diameter. If the diameter ofthe monitoring well is known, a number of standardconversion factors can be used to simplify theequation above.

The volume, in gallons per linear foot, for variousstandard monitoring well diameters can becalculated as follows:

For a 2-inch diameter well, the volume per linearfoot can be calculated as follows:

V = nr2(cf) [Equation 21= 3.14 (l/12 ft)2 7.48 gal/f?= 0.1632 gal/ft

Remember that if you have a 2-inch diameter well,you must convert this to the radius in feet to beable to use the equation.

The volume per linear foot for monitoring wells ofcommon size are as follows:

Well diameter

2-inch3-inch4-inch6-inch

v (volume in gal/ft.)

0.16320.36720.65281.4688

If you utilize the factors above, Equation 1 shouldbe modified as follows:

Well volume = h(v) [Equation 3]

where:h = height of water column (feet)V = volume in gallons per linear foot

from Equation 2


There are no specific quality assurance activitieswhich apply to the implementation of theseprocedures. However, the following general QAprocedures apply:

? All data must be documented on standardchain of custody forms, field data sheets orpersonal/site logbooks.

?? All instrumentation must be operated inaccordance with operating instructions as

3 7

supplied by the manufacturer, unlessotherwise specified in the work plan.Equipment checkout and calibrationactivities must occur p r i o r t osampling/operation and they must bedocumented.




This section is not applicable to this SOP

38

7.0 CONTROLLED PUMPING TEST: SOP #2157


The most reliable and commonly used method ofdetermining aquifer characteristics is by controlledaquifer pumping tests. Groundwater flow varies inspace and time and depends on the hydraulicproperties of the rocks and the boundary conditionsimposed on the groundwater system. Pumping testsprovide results that are more representative ofaquifer characteristics than those predicted by slugor bailer tests. Pumping tests require a greaterdegree of activity and expense, however, and are notalways justified for all levels of investigation. Forexample, slug tests may be acceptable at thereconnaissance level whereas pumping tests areusually performed as part of a feasibility study insupport of designs for aquifer remediation.

Aquifer characteristics which may be learned usingpumping tests include hydraulic conductivity (K),transmissivity (T), specific yield (Sy) for unconfinedaquifers, and storage coefficient (S) for confinedaquifers. These parameters can be determined bygraphical solutions and computerized programs.This Standard Operating Procedure (SOP) outlinesthe protocol for conducting controlled pumpingtests.

7.2 METHOD SUMMARY

It is desirable to monitor pre-test water levels at thetest site for about 1 week prior to performance ofthe pump test. This information allows for thedetermination of the barometric efficiency of theaquifer, as well as noting changes in head, due torecharging or pumping in the area adjacent to thewell. Prior to initiating the long term pump test, astep test is conducted to estimate the greatest flowrate that may be sustained by the pump well.

After the pumping well has recovered from the steptest, the long term pumping test begins. At thebeginning of the test, the discharge rate is set asquickly and accurately as possible. The water levelsin the pumping well and observation wells arerecorded accordingly with a set schedule. Data isentered on the Pump/Recovery Test Data Sheet(Appendix C). The duration of the test isdeterminated by project needs and aquifer

39

properties, but rarely goes beyond 3 days or untilwater levels become constant.




Interferences and potential problems include:

atmospheric conditionsimpact of local potable wellscompression of the aquifer due to trains,heavy traffic, etc.

EQUIPMENT/APPARATUS

tape measure (subdivided into tenths offeet)submersible pumpwater pressure transducerelectric water level indicatorweighted tapessteel tape (subdivided into tenths of feet)generatorelectronic data-logger (if transducermethod is used)watch or stopwatch with second handsemilogarithmic graph paper (if required)water proof ink pen and logbookthermometerappropriate references and calculatora barometer or recording barograph (fortests conducted in confined aquifers)heat shrinkselectrical tapeflashlights and lanternspH meterconductivity meterdischarge pipeflow meter

7.6 REAGENTS

No chemical reagents are used for this procedure;however, decontamination solutions may benecessary. If decontamination of equipment isrequired, refer to ERT SOP #2006, SamplingEquipment Decontamination and the site-specificwork plan.

7.7 PROCEDURES

7.7.1 Preparation

1.

2.

3.

4.

5.

6.

Determine the extent of the sampling effort, thesampling methods to be employed, and whichequipment and supplies are needed.

Obtain necessary sampling and monitoringequipment.

Decontaminate or preclean equipment, andensure that it is in working order.

Prepare scheduling and coordinate with staff,clients, and regulatory agency, if appropriate.

Perform a general site survey prior to site entryin accordance with the site-specific health andsafety plan.

Identify and mark all sampling locations.


1.

2.

3.

4.

5.

Review the site work plan and become familiarwith information on the wells to be tested.

Check and ensure the proper operation of allfield equipment. Ensure that the electronicdata-logger is fully charged, if appropriate.Test the electronic data-logger using acontainer of water. Always bring additionaltransducers in case of malfunctions.

Assemble a sufficient number of field dataforms to complete the field assignment.

Develop the pumping well prior to testing, perERT SOP #2156, Well Development.

Provide an orifice, weir, flow meter, containeror other type of water measuring device toaccurately measure and monitor the discharge

6.

7.

8.

from the pumping well.

Provide sufficient pipe to transport thedischarge from the pumping well to an areabeyond the expected cone of depression.Conducting a pumping test in contaminatedgroundwater may require treatment, specialhandling, or a discharge permit before thewater can be discharged.

The discharge pipe must have a gate valve tocontrol the pumping rate.

Determine if there is an outlet near the wellhead for water quality determination andsampling.

7.7.3 Pre-Test Monitoring

It is desirable to monitor pretest water levels at thetest site for about 1 week prior to performance ofthe test. This can be accomplished by using acontinuous-recording device such as a Stevensrecorder. This information allows the determinationof the barometric efficiency of the aquifer whenbarometric records are available. It also helpsdetermine if the aquifer is experiencing an increaseor decrease in head with time due to recharge orpumping in the nearby area, or diurnal effects ofevapotranspiration. Changes in barometric pressureare recorded during the test (preferably with an on-site barograph) in order to correct water levels forany possible fluctuations which may occur due tochanging atmospheric conditions. Pretest waterlevel trends are projected for the duration of thetest. These trends and/or barometric changes areused to “correct” water levels during the test so theyare representative of the hydraulic response of theaquifer due to pumping of the test well.

7.7.4 Step Test

Conduct a step test prior to initiating a long termpumping test. The purpose of a step test is toestimate the greatest flow rate that may besustained during a long term test. The test isperformed by progressively increasing the flow rateat 1 hour intervals. The generated drawdown versustime data is plotted on semilogarithmic graph paper,and the discharge rate is determined from thisgraph.

40

7.7.5 Pump Test

Time Intervals

After the pumping well has fully recovered from thestep test, the long term pumping test may start. Atthe beginning of the test, the discharge rate shouldbe set as quickly and accurately as possible. Thewater levels in the pumping well and observationwells will be recorded according to Tables 4 and 5below.

Water Level Measurements

Water levels will be measured as specified in ERTSOP #2151, Well Level Measurement. During theearly part of the test, sufficient personnel should be

available to have at least one person at eachobservation well and at the pumping well. After thefirst 2 hours, two people are usually sufficient tocontinue the test. It is not necessary that readingsat the wells be taken simultaneously. It is veryimportant that depth to water readings be measuredaccurately and readings recorded at the exact timemeasured. Alternately, individual pressuretransducers and electronic data-loggers may be usedto reduce the number of field personnel hoursrequired to complete the pumping test. A typicalaquifer pump test form is shown in Appendix C.

During a pumping test, the following data must berecorded accurately on the aquifer test data form.

1. Site ID -- A number assigned to identity aspecific site.

Table 4: Time Intervals for MeasuringDrawdown in the Pumped Well

Elapsed Time From Start of Test (Minutes)

0 - 10

Interval Between Measurements (Minutes)

0.5 - 11

10 - 15 1I I I

15 - 60 5

60-300 30

300-1440 60 I

1440 - termination 480

Table 5: Time Intervals for Measuring Drawdownin an Observation Well

Elapsed Time From Start of Test (Minutes) Interval Between Measurements (Minutes)

O-60 2

60 - 120 5

120 - 240 10

240 - 360 30

360-1440 60

1440 - termination 480

41

2. Location -- The location of the well in whichwater level measurements are being taken.

3. Distance from Pumped Well -- Distancebetween the observation well and the pumpingwell in feet.

4. Logging Company -- The company conductingthe pumping test.

5. Test Start Date -- The date when the pumpingtest began.

6. Test Start Time -- Start time, using a 24hourclock.

7. Static Water Level (Test Start) -- Depth towater, in feet and tenths of feet, in theobservation well at the beginning of thepumping test.

8. Test End Date -- The date when the pumpingtest was completed.

9. Test End Time -- End time, using a 24hourclock.

10. Static Water Level (Test End) -- Depth towater, in feet and tenths of feet, in theobservation well at the end of the pumping test.

11. Average Pumping Rate -- Summation of allentries recorded in the Pumping Rate (gal/min)column divided by the total number of PumpingRate (gal/min) readings.

12. Measurement Methods -- Type of instrumentused to measure depth-to-water (this mayinclude steel tape, electric sounding probes,Stevens recorders, or pressure transducers).

13. Comments -- Appropriate observations orinformation which have not been recordedelsewhere, including notes on sampling.

14. Elapsed Time (min) -- Time of measurementrecorded continuously from start of test (time00.00).

15. Depth to Water (ft) -- Depth to water, in feetand tenths of feet, in the observation well at thetime of the water level measurement.

16. Pumping Rate (gal/min) -- Plow rate of pumpmeasured from an orifice, weir, flow meter,

container or other type of water-measuringdevice.

Test Duration

The duration of the test is determined by the needsof the project and properties of the aquifer. Onesimple test for determining adequacy of data iswhen the log-time versus drawdown for the mostdistant observation well begins to plot as a straightline on the semilogarithmic graph paper. There areseveral exceptions to this simple rule of thumb,therefore, it should be considered a minimumcriterion. Different hydrogeologic conditions canproduce straight line trends on log-time versusdrawdown plots. In general, longer tests producemore definitive results. A duration of 1 to 3 days isdesirable, followed by a similar period of monitoringthe recovery of the water level. Unconfinedaquifers and partially penetrating wells may haveshorter test durations. Knowledge of the localhydrogeology, combined with a clear understandingof the overall project objectives, is necessary ininterpreting just how long the test should beconducted. There is no need to continue the test ifthe water level becomes constant with time. Thisnormally indicates that a hydrogeologic source hasbeen intercepted and that additional usefulinformation will not be collected by continuedpumping.


1. After completion of water level recoverymeasurements, decontaminate and/or disposeof equipment as per ERT SOP #2006,Sampling Equipment Decontamination.

2. When using an electronic data-logger, use thefollowing procedures.

?? Stop logging sequence.? Print data, or save memory and disconnect

battery at the end of the day’s activities.

3. Replace testing equipment in storagecontainers.

4. Check sampling equipment and supplies.Repair or replace all broken or damagedequipment.

5. Review field forms for completeness.

42

6. Interpret pumping/recovery test field results.

7.8 CALCULATIONS

There are several accepted methods for determiningaquifer properties such as transmissivity, storativity,and conductivity. However, the method to use isdependent on the characteristics of the aquiferbeing tested (confined, unconfined, leaky confininglayer, etc.). When reviewing pump test data, textsby Fetter, or Driscoll or Freeze and Cherry may beused to determine the method most appropriate toyour case. See the reference section on page 69.


Calibrate all gauges, transducers, flow meters, andother equipment used in conducting pumping testsbefore use at the site.

Obtain records of the instrument calibration and filewith the test data records. The calibration recordswill consist of laboratory measurements. Ifnecessary, perform any on-site zero adjustmentand/or calibration. Where possible, check all flowand measurement meters on-site using a containerof measured volume and stopwatch; the accuracy ofthe meters must be verified before testing proceeds.





43



This procedure can determine the horizontalhydraulic conductivity of distinct geologic horizonsunder in situ conditions. The hydraulic conductivity(K) is an important parameter for modeling theflow of groundwater in an aquifer.

8.2 METHOD SUMMARY

A slug test involves the instantaneous injection of aslug (a solid cylinder of known volume) orwithdrawal of a volume of water. A slug displacesa known volume of water from a well and measuresthe artificial fluctuation of the groundwater level.

There are several advantages to using slug tests toestimate hydraulic conductivities. First, estimatescan be made in situ, thereby avoiding errorsincurred in laboratory testing of disturbed soilsamples. Second, compared with pump tests, slugtests can be performed quickly and at relatively lowcost, because pumping and observation wells are notrequired. And last, the hydraulic conductivity ofsmall discrete portions of an aquifer can beestimated (e.g., sand layers in a clay).




? Only the hydraulic conductivity of the areaimmediately surrounding the well isestimated, which may not be representativeof the average hydraulic conductivity of thearea.

? The storage coefficient, S, usually cannotbe determined by this method.

45


The following equipment is needed to perform slugtests. All equipment which comes in contact withthe well should be decontaminated and tested priorto commencing field activities.

tape measure (subdivided into tenths offeet)water pressure transducerelectric water level indicatorweighted tapessteel tape (subdivided into tenths of feet)electronic data-logger (if transducermethod is used)stainless steel slug of a known volumewatch or stopwatch with second handsemilogarithmic graph paper (if required)waterproof ink pen and logbookthermometerappropriate references and calculatorelectrical tape21X microloggerCompaq portable computer or equivalentwith Grapher installed on the hard disk

REAGENTS

No chemical reagents are used in this procedure;however, decontamination solvents may benecessary. When decontaminating the slug orequipment, refer to ERT SOP #2006, SamplingEquipment Decontamination, and the site-specificwork plan.

8.7 PROCEDURES

8.7.1 Field Procedures

When the slug test is performed using an electronicdata-logger and pressure transducer, all data will bestored internally or on computer diskettes or tape.The information will be transferred directly to themain computer and analyzed. Keep a computerprintout of the data in the files as documentation.

If the slug test data is collected and recordedmanually, the slug test data form (Appendix C) will

be used to record observations. The slug test dataform should include the following information:

• site ID -- identification number assigned tothe site

?? location ID -- identification of locationbeing tested

?? date -- the date when the test data werecollected in this order: year, month, day

?

(e.g., 900131 for January 31, 1990)slug volume (ft3) = manufacturer’sspecification for the known volume ordisplacement of the slug device

? logger -- identifies the company or personresponsible for performing the fieldmeasurements

?? test method -- the slug device either isinjected or lowered into the well, or iswithdrawn or pulled-out from the monitorwell. Check the method that is applicableto the test situation being run.

• comments -- appropriate observations orinformation for which no other blanks areprovided.

? elapsed time (minutes) -- cumulative timereadings from beginning of test to end oftest, in minutes

?? depth to water (feet) -- depth to waterrecorded in tenths of feet

The following general procedures may be used tocollect and report slug test data. These proceduresmay be modified to reflect site-specific conditions:

1.

2.

3.

4.

5.

Decontaminate the transducer and cable.

Make initial water level measurements onmonitoring wells in an upgradient-to-downgradient sequence, if possible, to minimizethe potential for cross-contamination.

Before beginning the slug test , recordinformation into the electronic data-logger.The type of information may vary depending onthe model used. When using different model,consult the operator’s manual for the properdata entry sequence to be used.

Test wells from least contaminated to mostcontaminated, if possible.

Determine the static water level in the well bymeasuring the depth to water periodically forseveral minutes and taking the averagc of thereadings, (see SOP #2151, Water Level

6.

7.

8.

9.

10.

11.

12.

13.

Measurement).

Cover sharp edges of the well casing with ducttape to protect the transducer cables.

Install the transducer and cable in the well toa depth below the target drawdown estimatedfor the test but at least 2 feet from the bottomof the well. Be sure the depth of submergenceis within the design range stamped on thetransducer. Temporarily tape the transducercable to the well to keep the transducer at aconstant depth.

Connect the transducer cable to the electronicdata-logger.

Enter the initial water level and transducerdesign range into the recording deviceaccording to the manufacturer’s instructions.The transducer design range will be stampedon the side of the transducer. Record theinitial water level on the recording device.

“Instantaneously” introduce or remove a knownvolume or slug of water to the well. Anothermethod is to introduce a solid cylinder ofknown volume to displace and raise the waterlevel, allow the water level to restabilize andremove the cylinder. It is important to removeor add the volumes as quickly as possiblebecause the analysis assumes an “instantaneous”change in volume is created in the well.

Consider the moment of volume addition orremoval as time zero. Measure and record thedepth to water and the time at each reading.Depths should be measured to the nearest 0.01foot. The number of depth-time measurementsnecessary to complete the test is variable. It iscritical to make as many measurements aspossible in the early part of the test. Thenumber and intervals between measurementswill be determined from previous aquifer testsor evaluations.

Continue measuring and recording depth-timemeasurements until the water level returns toequilibrium conditions or a sufficient number ofreadings have been made to clearly show atrend on a semilogarithmic plot of time versusdepth.

Retrieve slug (if applicable).

40

Note: The time required for a slug test to becompleted is a function of the volume of the slug,the hydraulic conductivity of the formation and thetype of well completion. The slug volume should belarge enough that a sufficient number of water levelmeasurements can be made before the water levelreturns to equilibrium conditions. The length of thetest may range from less than a minute to severalhours. If the well is to be used as a monitoringwell, precautions against contaminating it should betaken. If water is added to the monitoring well, itshould be from an uncontaminated source andtransported in a clean container. Bailers ormeasuring devices should be decontaminated priorto the test. If tests are performed on more thanone monitoring well, care must be taken to avoidcross-contamination of the wells.

Slug tests should be conducted on relativelyundisturbed wells. If a test is conducted on a wellthat has recently been pumped for water samplingpurposes, the measured water level must be within0.1 foot of the static water level prior to sampling.At least 1 week should elapse between the drillingof a well and the performance of a slug test.


When using an electronic data-logger, use thefollowing procedure:

1. Stop logging sequence.

2. Print data.

3. Send data to computer by telephone.

4. Save memory and disconnect battery at the endof the day’s activities.


8.8 CALCULATIONS

The simplest interpretation of piezometer recoveryis that of Hvorslev (1951). The analysis assumes ahomogenous, isotropic medium in which soil andwater are incompressible. Hvorslev’s expression forhydraulic conductivity (K) is:

for L/R > 8

where:

K = hydraulic conductivity [feet/second]

r= casing radius [feet]= length of open screen (or open borehole)

[feet]R = filter pack (borehole) radius [feet]T ° = Basic Time Lag [seconds]; value of t on

semilogarithmic plot of (H-h)/(H-H°)vs. t, when (H-h)/(H-H°) = 0.37

where:

H = initial water level prior to removal of slugH° = water level at t = 0h = recorded water level at t> 0

(Hvorslev, 1951; Freeze and Cherry, 1979)

The Bower and Rice method is also commonly usedfor K calculations. However, it is much more timeconsuming than the Hvorslev method. Refer toFreeze and Cherry or Fetter for a discussion ofthese methods.



? All data must be documented on standardchain of custody forms, field data sheets, orwithin personal/site logbooks.

?? All instrumentation must be operated inaccordance with operating instructions assupplied by the manufacturer, unlessotherwise specified in the work plan.Equipment checkout and calibrationactivities must occur p r i o r t osampling/operation, and they must bedocumented.

The following specific quality assurance activity willapply:

K=r21n(L/R)2LT°

? Each well should be tested at least twice inorder to compare results.

4 7





48

APPENDIX A

Sampling Train Schematic

49

VACUUMBO

Figure 1: Sampling Train Schematic

SOP #2149

l / 4 ” I . D . T H I N W A L LTEFLON TUBING

l /4” S . S .SAMPLE PROBE

50

VACUUMBO

Figure 1: Sampling Train Schematic

SOP #2149

l / 4 ” I . D . T H I N W A L LTEFLON TUBING

l /4” S . S .SAMPLE PROBE

50

APPENDIX A

Sampling Train Schematic

49





48





48

Note: The time required for a slug test to becompleted is a function of the volume of the slug,the hydraulic conductivity of the formation and thetype of well completion. The slug volume should belarge enough that a sufficient number of water levelmeasurements can be made before the water levelreturns to equilibrium conditions. The length of thetest may range from less than a minute to severalhours. If the well is to be used as a monitoringwell, precautions against contaminating it should betaken. If water is added to the monitoring well, itshould be from an uncontaminated source andtransported in a clean container. Bailers ormeasuring devices should be decontaminated priorto the test. If tests are performed on more thanone monitoring well, care must be taken to avoidcross-contamination of the wells.

Slug tests should be conducted on relativelyundisturbed wells. If a test is conducted on a wellthat has recently been pumped for water samplingpurposes, the measured water level must be within0.1 foot of the static water level prior to sampling.At least 1 week should elapse between the drillingof a well and the performance of a slug test.


When using an electronic data-logger, use thefollowing procedure:

1. Stop logging sequence.

2. Print data.

3. Send data to computer by telephone.

4. Save memory and disconnect battery at the endof the day’s activities.


8.8 CALCULATIONS

The simplest interpretation of piezometer recoveryis that of Hvorslev (1951). The analysis assumes ahomogenous, isotropic medium in which soil andwater are incompressible. Hvorslev’s expression forhydraulic conductivity (K) is:

for L/R > 8

where:

K = hydraulic conductivity [feet/second]

r= casing radius [feet]= length of open screen (or open borehole)

[feet]R = filter pack (borehole) radius [feet]T ° = Basic Time Lag [seconds]; value of t on

semilogarithmic plot of (H-h)/(H-H°)vs. t, when (H-h)/(H-H°) = 0.37

where:

H = initial water level prior to removal of slugH° = water level at t = 0h = recorded water level at t> 0

(Hvorslev, 1951; Freeze and Cherry, 1979)

The Bower and Rice method is also commonly usedfor K calculations. However, it is much more timeconsuming than the Hvorslev method. Refer toFreeze and Cherry or Fetter for a discussion ofthese methods.



? All data must be documented on standardchain of custody forms, field data sheets, orwithin personal/site logbooks.

?? All instrumentation must be operated inaccordance with operating instructions assupplied by the manufacturer, unlessotherwise specified in the work plan.Equipment checkout and calibrationactivities must occur p r i o r t osampling/operation, and they must bedocumented.

The following specific quality assurance activity willapply:

K=r21n(L/R)2LT°

? Each well should be tested at least twice inorder to compare results.

4 7

be used to record observations. The slug test dataform should include the following information:

• site ID -- identification number assigned tothe site

?? location ID -- identification of locationbeing tested

?? date -- the date when the test data werecollected in this order: year, month, day

?

(e.g., 900131 for January 31, 1990)slug volume (ft3) = manufacturer’sspecification for the known volume ordisplacement of the slug device

? logger -- identifies the company or personresponsible for performing the fieldmeasurements

?? test method -- the slug device either isinjected or lowered into the well, or iswithdrawn or pulled-out from the monitorwell. Check the method that is applicableto the test situation being run.

• comments -- appropriate observations orinformation for which no other blanks areprovided.

? elapsed time (minutes) -- cumulative timereadings from beginning of test to end oftest, in minutes

?? depth to water (feet) -- depth to waterrecorded in tenths of feet

The following general procedures may be used tocollect and report slug test data. These proceduresmay be modified to reflect site-specific conditions:

1.

2.

3.

4.

5.

Decontaminate the transducer and cable.

Make initial water level measurements onmonitoring wells in an upgradient-to-downgradient sequence, if possible, to minimizethe potential for cross-contamination.

Before beginning the slug test , recordinformation into the electronic data-logger.The type of information may vary depending onthe model used. When using different model,consult the operator’s manual for the properdata entry sequence to be used.

Test wells from least contaminated to mostcontaminated, if possible.

Determine the static water level in the well bymeasuring the depth to water periodically forseveral minutes and taking the averagc of thereadings, (see SOP #2151, Water Level

6.

7.

8.

9.

10.

11.

12.

13.

Measurement).

Cover sharp edges of the well casing with ducttape to protect the transducer cables.

Install the transducer and cable in the well toa depth below the target drawdown estimatedfor the test but at least 2 feet from the bottomof the well. Be sure the depth of submergenceis within the design range stamped on thetransducer. Temporarily tape the transducercable to the well to keep the transducer at aconstant depth.

Connect the transducer cable to the electronicdata-logger.

Enter the initial water level and transducerdesign range into the recording deviceaccording to the manufacturer’s instructions.The transducer design range will be stampedon the side of the transducer. Record theinitial water level on the recording device.

“Instantaneously” introduce or remove a knownvolume or slug of water to the well. Anothermethod is to introduce a solid cylinder ofknown volume to displace and raise the waterlevel, allow the water level to restabilize andremove the cylinder. It is important to removeor add the volumes as quickly as possiblebecause the analysis assumes an “instantaneous”change in volume is created in the well.

Consider the moment of volume addition orremoval as time zero. Measure and record thedepth to water and the time at each reading.Depths should be measured to the nearest 0.01foot. The number of depth-time measurementsnecessary to complete the test is variable. It iscritical to make as many measurements aspossible in the early part of the test. Thenumber and intervals between measurementswill be determined from previous aquifer testsor evaluations.

Continue measuring and recording depth-timemeasurements until the water level returns toequilibrium conditions or a sufficient number ofreadings have been made to clearly show atrend on a semilogarithmic plot of time versusdepth.

Retrieve slug (if applicable).

40



This procedure can determine the horizontalhydraulic conductivity of distinct geologic horizonsunder in situ conditions. The hydraulic conductivity(K) is an important parameter for modeling theflow of groundwater in an aquifer.

8.2 METHOD SUMMARY

A slug test involves the instantaneous injection of aslug (a solid cylinder of known volume) orwithdrawal of a volume of water. A slug displacesa known volume of water from a well and measuresthe artificial fluctuation of the groundwater level.

There are several advantages to using slug tests toestimate hydraulic conductivities. First, estimatescan be made in situ, thereby avoiding errorsincurred in laboratory testing of disturbed soilsamples. Second, compared with pump tests, slugtests can be performed quickly and at relatively lowcost, because pumping and observation wells are notrequired. And last, the hydraulic conductivity ofsmall discrete portions of an aquifer can beestimated (e.g., sand layers in a clay).




? Only the hydraulic conductivity of the areaimmediately surrounding the well isestimated, which may not be representativeof the average hydraulic conductivity of thearea.

? The storage coefficient, S, usually cannotbe determined by this method.

45


The following equipment is needed to perform slugtests. All equipment which comes in contact withthe well should be decontaminated and tested priorto commencing field activities.

tape measure (subdivided into tenths offeet)water pressure transducerelectric water level indicatorweighted tapessteel tape (subdivided into tenths of feet)electronic data-logger (if transducermethod is used)stainless steel slug of a known volumewatch or stopwatch with second handsemilogarithmic graph paper (if required)waterproof ink pen and logbookthermometerappropriate references and calculatorelectrical tape21X microloggerCompaq portable computer or equivalentwith Grapher installed on the hard disk

REAGENTS

No chemical reagents are used in this procedure;however, decontamination solvents may benecessary. When decontaminating the slug orequipment, refer to ERT SOP #2006, SamplingEquipment Decontamination, and the site-specificwork plan.

8.7 PROCEDURES

8.7.1 Field Procedures

When the slug test is performed using an electronicdata-logger and pressure transducer, all data will bestored internally or on computer diskettes or tape.The information will be transferred directly to themain computer and analyzed. Keep a computerprintout of the data in the files as documentation.

If the slug test data is collected and recordedmanually, the slug test data form (Appendix C) will

6. Interpret pumping/recovery test field results.

7.8 CALCULATIONS

There are several accepted methods for determiningaquifer properties such as transmissivity, storativity,and conductivity. However, the method to use isdependent on the characteristics of the aquiferbeing tested (confined, unconfined, leaky confininglayer, etc.). When reviewing pump test data, textsby Fetter, or Driscoll or Freeze and Cherry may beused to determine the method most appropriate toyour case. See the reference section on page 69.


Calibrate all gauges, transducers, flow meters, andother equipment used in conducting pumping testsbefore use at the site.

Obtain records of the instrument calibration and filewith the test data records. The calibration recordswill consist of laboratory measurements. Ifnecessary, perform any on-site zero adjustmentand/or calibration. Where possible, check all flowand measurement meters on-site using a containerof measured volume and stopwatch; the accuracy ofthe meters must be verified before testing proceeds.





43

2. Location -- The location of the well in whichwater level measurements are being taken.

3. Distance from Pumped Well -- Distancebetween the observation well and the pumpingwell in feet.

4. Logging Company -- The company conductingthe pumping test.

5. Test Start Date -- The date when the pumpingtest began.

6. Test Start Time -- Start time, using a 24hourclock.

7. Static Water Level (Test Start) -- Depth towater, in feet and tenths of feet, in theobservation well at the beginning of thepumping test.

8. Test End Date -- The date when the pumpingtest was completed.

9. Test End Time -- End time, using a 24hourclock.

10. Static Water Level (Test End) -- Depth towater, in feet and tenths of feet, in theobservation well at the end of the pumping test.

11. Average Pumping Rate -- Summation of allentries recorded in the Pumping Rate (gal/min)column divided by the total number of PumpingRate (gal/min) readings.

12. Measurement Methods -- Type of instrumentused to measure depth-to-water (this mayinclude steel tape, electric sounding probes,Stevens recorders, or pressure transducers).

13. Comments -- Appropriate observations orinformation which have not been recordedelsewhere, including notes on sampling.

14. Elapsed Time (min) -- Time of measurementrecorded continuously from start of test (time00.00).

15. Depth to Water (ft) -- Depth to water, in feetand tenths of feet, in the observation well at thetime of the water level measurement.

16. Pumping Rate (gal/min) -- Plow rate of pumpmeasured from an orifice, weir, flow meter,

container or other type of water-measuringdevice.

Test Duration

The duration of the test is determined by the needsof the project and properties of the aquifer. Onesimple test for determining adequacy of data iswhen the log-time versus drawdown for the mostdistant observation well begins to plot as a straightline on the semilogarithmic graph paper. There areseveral exceptions to this simple rule of thumb,therefore, it should be considered a minimumcriterion. Different hydrogeologic conditions canproduce straight line trends on log-time versusdrawdown plots. In general, longer tests producemore definitive results. A duration of 1 to 3 days isdesirable, followed by a similar period of monitoringthe recovery of the water level. Unconfinedaquifers and partially penetrating wells may haveshorter test durations. Knowledge of the localhydrogeology, combined with a clear understandingof the overall project objectives, is necessary ininterpreting just how long the test should beconducted. There is no need to continue the test ifthe water level becomes constant with time. Thisnormally indicates that a hydrogeologic source hasbeen intercepted and that additional usefulinformation will not be collected by continuedpumping.


1. After completion of water level recoverymeasurements, decontaminate and/or disposeof equipment as per ERT SOP #2006,Sampling Equipment Decontamination.

2. When using an electronic data-logger, use thefollowing procedures.

?? Stop logging sequence.? Print data, or save memory and disconnect

battery at the end of the day’s activities.

3. Replace testing equipment in storagecontainers.

4. Check sampling equipment and supplies.Repair or replace all broken or damagedequipment.


42

APPENDIX B

HNU Field Protocol

51

HNU Field ProtocolSOP

Startup Procedure

1. Before attaching the probe, check the functionswitch on the control panel to ensure that it isin the ‘off position. Attach the probe byplugging it into the interface on the top of thereadout module. Use care in aligning theprongs in the probe cord with the plug in; donot force.

2. Turn the function switch to the battery checkposition. The needle on the meter should readwithin or above the green area on the scale. Ifnot, recharge the battery. If the red indicatorlight comes on, the battery needs recharging.

3. Turn the function switch to any range setting.For no more than 2 to 3 seconds look into theend of the probe to see if the lamp is on. If itis on, you will see a purple glow. Do not stareinto the probe any longer than three seconds.Long term exposure to UV light can damageeyes. Also, listen for the hum of the fan motor.

4. To zero the instrument, turn the function switchto the standby position and rotate the zeroadjustment until the meter reads zero. Acalibration gas is not needed since this is anelectronic zero adjustment. If the spanadjustment setting is changed after the zero isset, the zero should be rechecked and adjusted,if necessary. Wait 15 to 20 seconds to ensurethat the zero reading is stable. If necessary,readjust the zero.

Operational Check

1. Follow the startup procedure.

2. With the instrument set on the 0-20 range, holda solvent-based Magic Marker near the probetip. If the meter deflects upscale, theinstrument is working.

Field Calibration Procedure

1 . F o l l o w t h e s t a r t u p p r o c e d u r e a n d t h eoperational check.

#2149

2. Set the function switch to the range setting forthe concentration of the calibration gas.

3. Attach a regulator (HNU 101-351) to adisposable cylinder of isobutylene gas. Connectthe regulator to the probe of the HNU with apiece of clean Tygon tubing. Turn the valve onthe regulator to the ‘on’ position.

4. After 15 seconds, adjust the span dial until themeter reading equals the concentration of thecalibration gas used. The calibration gas isusually 100 ppm of isobutylene in zero air. Thecylinders are marked in benzene equivalents forthe 10.2 eV probe (approximately 55 ppmbenzene equivalent) and for the 11.7 eV probe(approximately 65 ppm benzene equivalent).Be careful to unlock the span dial beforeadjusting it. If the span has to be set below 3.0calibration, the lamp and ion chamber shouldbe inspected and cleaned as appropriate. Forcleaning of the 11.7 eV probe, only use anelectronic-grade, oil-free freon or similar water-free, grease-free solvent.

5. Record in the field log: the instrument ID #(EPA decal or serial number if the instrumentis a rental); the initial and final span settings;the date and time; concentration and type ofcalibration used; and the name of the personwho calibrated the instrument.

Operation

1.

2.

3.

4.

Follow the startup procedure, operationalcheck, and calibration check.

Set the function switch to the appropriaterange. If the concentration of gases or vaporsis unknown, set the function switch to the 0-20ppm range. Adjust it if necessary.

While taking care not to permit the HNU to beexposed to excessive moisture, dirt , orcontamination, monitor the work activity asspecified in the site health and safety plan.

When the activity is completed or at the end ofthe day, carefully clean the outside of the HNUwith a damp disposable towel to remove any

53

visible dirt. Return the HNU to a secure areaand place on charge.

plastic to prevent it from becoming contaminatedand to prevent water from getting inside in theevent of precipitation.

5. With the exception of the probe’s inlet andexhaust, the HNU can be wrapped in clear

54

APPENDIX C

Forms

55

Well Completion Form

SOP #2150 PAGE-OF-

M O N I T O R W E L L I N S T A L L A T I O NJob No., Date Drilled: Well No.1

E l e v a t i o n P a d Top of Steel Casing:

Casing Size & Type: S c r e e n S i z e :

56

Groundwater Level Data Form

SOP #2151

SITE NAME:

P A G E - O F -

LOG DATE: LOGGER NAME:

MEASUREMENT REFERENCE POINT: -TOP OF GROUND -TOP OF CASING

DEPTH TOLOCATION TIME WATER (FT) COMMENTS

57

Pump/Recovery Test Data Sheet

SOP #2157 PAGE-OF-

SITE ID: DISTANCE FROM PUMPED WELL (FT):

LOCATION: LOGGER:

TEST START I TEST END

I DATE:

TIME: I TIME:

STATIC WATER LEVEL (FT): I STATIC WATER LEVEL (FT):

AVERAGE PUMPING RATE (GAL/MIN):

MEASUREMENT METHODS:

COMMENTS:

I I I I

ELAPSEDTIME(MIN)

0.00

PUMP TESTDEPTH TO

WATER (FT)

PUMPINGRATE

(GAL/MIN)

RECOVERYTEST ELAPSED DEPTH TO

TIME (MIN) WATER (FT)

0.00

58

Pump/Recovery Test Data Sheet (Continued)

SOP #2157 PAGE-OF-

SITE ID:

LOCATION:

ELAPSEDTIME(MIN)

PUMP TESTDEPTH TO

WATER (FT)

DATE:

LOGGER:

PUMPING RECOVERYRATE TEST ELAPSED

(GAL/MIN) TIME (MIN)DEPTH TO

WATER (FT)

Slug Test Data Form

SOP #2158 PAGE-OF-

I DATE:

SITE ID: SLUG VOLUME (FT3):

LOCATION ID: LOGGER:

TEST METHOD: _ SLUG INJECTION _ SLUG WITHDRAWAL

COMMENTS:

60

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Barcelona, M.J., J.A. Helfrich, and E.E. Garske. 1985. Sampling Tubing Effects on Groundwater Samples.Analy. Chem. 57: 460-463.

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Boulton, N.S. 1954. The Drawdown of the Water-Table under Non-Steady Conditions Near a Pumped Wellin an Unconfined Formation. Paper 5979 in Proceedings of the Institution of Civil Engineers. 3:564.

Boulton, N.S. 1993. Analysis of Data from Non-Equilibrium Pumping Tests Allowing for Delayed Yieldfrom Storage, Paper 6693 in Proceedings of the Institution of Civil Engineers. 26: 469-82.

Bower, H. 1978. Groundwater Hydrology. McGraw-Hill, New York, New York.

Bower, H. and R.C. Rice. 1976. A Slug Test for Determining Hydraulic Conductivity of UnconfinedAquifers with Completely or Partially Penetrating Wells. Water Resources Research. 12 (3): 233-238.

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Cooper, Jr., H.H., and C.E. Jacob. 1946. A Generalized Graphical Method for Evaluating FormationConstants and Summarizing Well-Field History. American Geophysical Union Transactions. 27 (4):526-534.

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61

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62

U.S. Department of the Interior. 1977. Ground Water Manual, Bureau of Reclamation. U.S. GovernmentPrinting Office, New York, New York.

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