ARFQ DEP2500000018-Attachment 9 Soil Gas Sampling (130) (2).pdf

Agency Document ID Number

DLR-OER-130

Soil Gas Sampling

SOP OER-0130

Prepared for:

West Virginia Department of Environmental Protection

Division of Land Restoration Office of Environmental Remediation

Author Revision

No.

Effective

Date Description of Changes

Type of Change

Ross Brittain

0.0 1/10/2021 Created new SOP and SOP ID# Editorial, Technical

APPROVED:

Name Date

SOIL GAS SAMPLING

SOP OER-0130

Table of Contents

1.0 Scope and Application

2.0 Summary of Method

2.1 Soil Gas Wells

2.2 Sub-Slab Probes

3.0 Sample Preservation, Containers, Handling, and Storage

3.1 Tedlar Bags

3.2 Summa Canisters

4.0 Interferences and Potential Problems

4.1 General

4.2 Soil Probe Clogging

4.3 Underground Utilities

5.0 Equipment Apparatus

5.1 Soil Gas Wells

5.1.1 Slam Bars/Stainless Steel Hand Augers

5.1.2 Direct-Push (Geoprobe) Method

5.2 Sub-Slab Probes

6.0 Reagents

7.0 Procedures

7.1 Soil Gas Wells Installation

7.1.1 Slam Bar/Stainless Steel Hand Auger Method

7.1.2 Direct-Push Method

7.2 Sub-Slab Probe

7.2.1 Assembly and Installation

7.2.2 Sampling Set-Up

7.2.3 Repairing a Loose Probe

7.3 Tedlar Bag Sampling

7.4 Summa Canister Sampling

8.0 Calculations

9.0 Quality Assurance/Quality Control

9.1 Sample Probe Contamination

9.2 Sample Train Contamination

9.3 PID/FID Calibration

9.4 Trip Blanks

9.4.1 Tedlar Bags

9.4.2 Summa Canisters

9.5 Field Blanks

9.5.1 Tedlar Bags

9.5.2 Summa Canisters

9.6 Trip Standards

9.7 Lot Blanks

9.7.1 Tedlar Bags

9.7.2 Summa Canisters

9.8 Duplicate Samples

9.9 Spikes

10.0 Data Validation

11.0 Health and Safety

12.0 References

List of Acronyms and Abbreviations

AC Alternating Current oC/oF Degrees Celsius/Degrees Fahrenheit

FID Flame Ionization Detector

GC Gas Chromatography

GC/MS Gas Chromatography/Mass Spectrometry

GPS Global Positioning System

HASP Health and Safety Plan

HAZWOPER Hazardous Waste Operations and Emergency Response

HDPE High Density Polyethylene

HEPA High Efficiency Particulate Air

HPLC High Performance Liquid Chromatography

IDW Investigation Derived Wasted

L Liter

NPT National Pipe Thread

OD Outer Diameter

OER Office of Environmental Remediation

OSHA Occupational Safety and Health Administration

PID Photoionization Detector

PPE Personal Protective Equipment

PVC Polyvinyl Chloride

QA/QC Quality Assurance/Quality Control

SAP Sampling and Analysis Plan

SAWP Site Assessment Work Plan

SDS Safety Data Sheet

SOP Standard Operating Procedure

SVOC Semi-Volatile Organic Compound

VOC Volatile Organic Compound

USEPA United States Environmental Protection Agency

WVDEP West Virginia Department of Environmental Protection

Disclaimer: Any mention in this SOP of any products or services does not constitute or imply the endorsement, recommendation or favoring by WVDEP or any of its employees or contractors acting on its behalf.

1.0 SCOPE AND APPLICATION

Vapor intrusion of volatile organic compounds (VOCs), some semi-volatile organic compounds (SVOCs) and some vapor-phase metals (e.g., mercury) is often a leading risk pathway for contaminated sites, especially those with petroleum and/or halogenated compounds. Methods for identifying and tracing the movement of underground vapor-phase contaminants is critical to protecting human health. The purpose of this standard operating procedure (SOP) is to outline the methods used to install soil gas wells and sub-slab probes, as well as collecting soil gas using Tedlar bags and/or Summa canisters. Alternate methods of collecting samples, such as sorbent tubes, may be proposed for the site and the West Virginia Department of Environmental Protection (WVDEP) will review the merits of such alternatives for potential approval. These procedures may be varied or changed as required, dependent upon site conditions, equipment limitations or limitations imposed by the procedure. Refer to the site-specific Sampling and Analysis Plan or Site Assessment Work Plan (SAWP) for details on the procedures to be used at the site. The procedures utilized at a site should be documented and included in the site investigation report.

2.0 SUMMARY OF METHOD

2.1 Soil Gas Wells

A hole is driven into the ground using manual (e.g., slam bar) or power driven mechanical (e.g., Geoprobe) methods. A probe made from inert materials (e.g., stainless steel, copper, brass, PVC, or HDPE) is connected to ¼-inch outer diameter (OD) tubing inserted into the hole. Once the probe is inserted, silica sand should be poured into the hole so that the probe is covered by no less than six inches of silica sand. The remaining annular space in the hole shall be filled with expandable clay (such as bentonite chips) and wetted so that a seal is created between the sand-packed probe and the ambient air. The interstitial gases may be pulled through the probe using an air sampling pump where the sample may be stored in a Tedlar bag.

Summa canisters do not require an air sampling pump, but rather are sampled by soil gas equilibration with the evacuated Summa canister. Specific details for sampling at any location should be found in the Sampling and Analysis Plan (SAP) or Site Assessment Work Plan (SAWP, hereafter both are referred to as SAWP).

2.2 Sub-Slab Probes

Sub-slab probes can be installed by assembling a probe following the procedures outlined in this SOP, or installing a vapor probe kit (e.g., VaporPin®) using the manufacturer’s SOP can be used to ease the installation procedures. Using a ⅜” diameter drill bit and an electric hammer drill or rotary hammer, an inner or pilot hole is drilled into the concrete slab to a depth ~2 inches below the slab. An outer hole is drilled to a depth of ~1⅜ inches using a 1-inch diameter drill bit and the pilot hole as the center. The 1-inch drill bit is then replaced by the ⅜-inch drill bit and the pilot hole is drilled through the slab and several inches into the subsurface soils.

After drilling is complete, a probe made from inert materials (e.g., stainless steel, copper, or brass) probe is assembled, inserted into the pre-drilled hole, flush-mounted with the surrounding slab so it will not interfere with traffic and cemented into place. Tubing is then attached to the probe assembly and to a sample container/system. Specific details for sampling at any location should be found in the SAWP.

3.0 SAMPLE PRESERVATION, CONTAINERS, HANDLING, AND STORAGE

3.1 Tedlar Bags

Soil gas samples can be collected in 1.0 liter (L) Tedlar bags, which should be stored in the dark (e.g., opaque containers) and protected from damage during transit to the laboratory. Sample bags should be kept at ambient temperatures and out of direct sunlight and analyzed within 48 hours of sample collection.

3.2 Summa Canisters

Summa canister have up to a 6.0 L capacity and are certified clean by gas chromatography/mass spectrometry (GC/MS) before collecting samples in the field. Canisters are stored and shipped in travel cases and should be analyzed within 30 days of sample collection. The canister should be fitted with a regulator valve properly calibrated by the laboratory to allow a maximum flow rate of 200 milliliters per minute (mL/min).

4.0 INTERFERENCES AND POTENTIAL PROBLEMS

4.1 General

Physical and chemical characteristics of the soils and soil moisture can affect the concentrations of VOCs in soil gas. Highly charged soil particles, such as clays, can cause VOCs to be tightly adsorbed to the soils, and highly soluble compounds can dissolve in soil water or associate with organic matter in the soil and reduce the concentrations in the interstitial pore spaces. Fine textured soil may also impede the movement of soil vapors or reduce the sample volume available. High or perched water tables and impermeable subsurface layers may also interfere with the movement and sampling of soil gas. Soil Conservation Service soil surveys and other existing knowledge of site geology should be consulted prior to planning a soil gas survey. Importantly, it has been found that lighter SVOCs, particularly Naphthalene, may have significant sample losses in cool conditions (Hayes et al. 2005) and differences in soil temperatures in the upper profile can lead to variations in soil gas concentrations by a factor of two for all VOCs (Luo et al. 2009, USEPA 2010, Hers et al. 2014, Johnson and Deeb 2014).

Accordingly, WVDEP recommends that soil gas be sampled when the ambient temperature is at least 21°C (70°F), especially when sampling for Naphthalene.

WVDEP may require additional samples be collected at a time when ambient temperature is at least 21°C to verify the data if soil vapor is collected during periods of relatively low soil and ambient air temperatures, especially when initial sample concentrations are greater than one-half of benchmark values.

4.2 Soil Probe Clogging

Clogging of the soil gas probes is a common problem, best identified by using an in-line gauge or by listening for the sound that the pump is laboring. Clogging can usually be remedied by using a wire cable to clear the probe.

4.3 Underground Utilities

An underground utility search must be completed prior to selecting the sample locations by calling Miss Utility West Virginia at 811, or using the West Virginia 811 App. Additionally, the local utility companies can be contacted and requested to mark the locations of their underground lines. Each sample location should also be screened with a metal detector or magnetometer to verify that no metallic pipes, drums or other objects are present. Installation of sub-slab sample probes should also take place after first locating water, sanitary sewer, gas, electric or other potential buried hazards under the foundation/floor. The biggest and most constant threat to personnel safety is the existence of rebar in the concrete slab, since a significant amount of structures utilize rebar grids for floor construction.

5.0 EQUIPMENT APPARATUS

5.1 Soil Gas Wells

5.1.1 Slam Bar/Stainless Steel Hand Auger Method

Slam bar or Stainless Steel Hand Auger Soil gas probes (stainless steel screen, ¼-inch OD, 5-foot length) Flexible wire or cable “Quick Connect” fittings, if applicable Bentonite clay Vacuum box Pumps, capable of drawing approximately 3.0 L/min ¼-inch OD tubing (type of tubing contingent upon site and sample requirements), ~3-ft length Tedlar bags, 1.0-L, if applicable Summa canisters (plus shipping cases), if applicable Sample documentation (soil gas sample labels, field data sheets, logbook, etc.)

PID/FID for field air monitoring, if applicable Cooler(s) Metal detector or magnetometer, if applicable Portable GC instrument, if applicable Large plastic bags Silica sand Tubing cutter

5.1.2 Direct-Push (Geoprobe) Method

Tubing: Polyethylene or Teflon

Gas sampling cap Probe rods Tubing adaptor(s) Expendable point holder, threaded Expendable drive point(s) O-rings for expendable point holder O-rings for adaptor O-rings for probe rods O-rings for gas sampling cap Vacuum pumps PID/FID for field air monitoring Tape Tedlar bags, 1.0-L, if applicable Summa canisters (plus shipping cases), if applicable Sample documentation (soil gas sample labels, field data sheets, logbook, etc.)

Metal detector or magnetometer, if applicable Cooler(s) Large dark plastic bags Portable GC instrument, if applicable Silica sand Tubing cutter

5.2 Sub-Slab Probes

PID/FID for field air monitoring, if applicable Modeling clay Hammer Drill or Rotary Hammer Alternating current extension cord Alternating current generator, if AC power is not available on site Hammer or Rotary Hammer drill bits, ⅜” and 1” diameter Portable vacuum cleaner with HEPA filter 1 - ¾-inch open end wrench or 1-medium adjustable wrench 2 – 9/16-inch open end wrenches or 2-small adjustable wrenches Hex head wrench, ¼-inch Tubing cutter Disposable non-plastic cups, ~5 ounce Disposable non-plastic mixing device (e.g., craft stick, tongue depressor, etc.)

Swagelok SS-400-7-4 Female Connector, ¼-inch National Pipe Thread

(NPT) to ¼-inch Swagelok connector, or equivalent Swagelok SS-400-1-4 Male Connector, ¼-inch NPT to ¼-inch Swagelok connector, or equivalent ¼-inch NPT flush mount hex socket plug, Teflon-coated ¼-inch OD stainless steel tubing, pre-cleaned, instrument grade

¼-inch OD Teflon tubing Teflon thread tape ⅛-inch OD stainless steel rod, 12-inch to 24-inch length Swagelok Tee, optional (SS-400-3-4TMT or SS-400-3-4TTM), or equivalent

6.0 REAGENTS

Refer to the site-specific SAWP for the preservatives required for the specified analysis to be performed. The following reagents are generally used for soil gas sampling in a soil gas well:

Calibration and spike gases Deionized water Methanol, High Performance Liquid Chromatography (HPLC) grade Ultra-zero grade compressed air Bentonite

The following reagents are generally used for soil gas sampling from sub-slab probes:

Tap water, for mixing anchoring cement Anchoring cement Modeling clay/Bentonite

7.0 PROCEDURES

7.1 Soil Gas Well Installation

7.1.1 Slam Bar/Stainless Steel Hand Auger Method

1. Before digging/drilling the hole, a soil gas probe made from inert materials (e.g., stainless steel, copper, brass, PVC, or HDPE) is constructed. Example probe construction includes ¼-inch outer diameter (OD) stainless steel (USEPA Environmental Response Team 2001), and 1-inch PVC 0.010-slot well screen, with a screen length at least 1-ft long. A PVC busing fitted with a ¼-inch nylon hose bard is installed on the top of the probe to allow for connecting sample tubing, and a PVC cap is fitted on the bottom. All connections must be threaded or friction fit and no solvent or glue can be used to prevent false detections of VOCs.

2. A hole slightly deeper than the required depth is made using a piston slam bar or stainless steel hand auger. Generally, the well should be approximately 5-ft deep to assess the soil gas in the typical basement zone. Soil gas wells can be deeper than 5-ft, especially if the near-source zone is much deeper, but should not be less than 5-ft deep unless the presence of shallow groundwater prevents sampling soil gas at a depth of 5-ft or deeper. If shallow groundwater is present, consider the possibility of assessing soil gas via sub-slab samples, but if sub-slab samples would not allow adequate spatial cover to assess future buildings then make the soil gas well as deep as possible. If depths deeper than 5-ft are required, use a piston slam bar with extensions.

3. Drive the slam bar rod or dig the hole using an auger to the desired depth.

After the hole is made, the slam bar/hand auger is carefully withdrawn to prevent the collapse of the walls.

4. The soil gas probe is carefully inserted into the hole. The probe is inserted to full depth of the hole, then pulled up three to six inches. The probe is cleared by moving the cable up and down several times.

5. The annular space between the probe and the borehole should be filled with a silica sand pack from the bottom of the borehole to at least 6 inches above the top of the probe. A bentonite grout seal should be placed in the annual space between the sample tubing connected to the probe and the borehole above the sand pack to the surface, or the probe may have a steel manway installed.

7.1.2 Direct-Push Method

1. Direct-push sampling technology refers to soil gas samplers that are inserted into the ground without the use of slam bars, demolition hammers, or drilling rigs, such as a Geoprobe.

2. Sampling probes, consisting of 3-foot sections of flush-threaded, 1¼-inch hardened steel alloy steel rod tipped by an expendable steel point, are available from Direct-Push suppliers and are driven into the ground to the target depth (default depth is 5-ft, but may be deeper if specified in the SAWP). The probe tools are withdrawn to release the expendable tip and allow soil gas to flow into the tool’s tubing.

3. To ensure a representative soil gas sample, a discrete volume of gas is purged to rid the tubing of atmospheric air and allow the subsurface soil gas to enter the probe tubing. The volume of gas removed is determined by the volume of tubing used in the probe necessary to remove two times the volume of the ambient air in the tubing.

4. After allowing the system to return to atmospheric pressure, an aliquot of soil gas is withdrawn from the probe. Duplicate samples are collected as necessary and required in the site-specific SAWP.

5. If semi-permanent soil gas installations are required, the probe remains in the hole, which may be sealed by backfilling with clean sand, soil, or bentonite.

7.2 Sub-Slab Probe

7.2.1 Assembly and Installation

Note that this assembly and installation is based on creating a sub-slab probe from scratch. Project Managers can use this method or alternately use a pre-manufactured vapor probe kit, such as Vapor Pin®, and follow their installation SOP to ease the process.

1. Drill a ⅜-inch diameter inner or pilot hole to a depth of 2 inches below the slab.

2. Using the ⅜-inch pilot hole as your center, drill a 1-inch diameter outer hole to a depth of 1⅜ inches. Using a pre-assembled probe for testing the depth may facilitate the process. Vacuum out any cuttings from the hole.

3. Re-drill the ⅜-inch inner or pilot hole through the slab and a few inches into the sub-slab material to clear out the hole. Vacuum out any cuttings from the hole.

4. Determine the length of stainless steel tubing required to reach from the bottom of the outer hole, through the slab and into the open cavity below the slab. To avoid obstruction/clogging of the probe tube, ensure that it does not contact the sub-slab material. Using a tube cutter, cut the tubing to the desired length.

5. Attach the measured length (typically 8-12 inches) of ¼-inch OD stainless steel tubing to a female connecter (e.g., Swagelok SS-400-7-4, or equivalent) with the nut. Tighten the nut.

6. Insert the ¼-inch hex socket plug into the female connector. Tighten the plug.

Do not over tighten. If excessive force is required to remove the plug during the sample set up phase, the probe may break loose from the anchoring cement. The sampling probe may be pre-assembled.

7. Place a small amount of clean modeling clay around the stainless steel tubing adjacent to the nut, which connects the stainless steel tubing to the female connector. Use a sufficient amount of modeling clay so that the completed probe will create a seal between the outer and inner holes, when placed in the outer hole. The clay seal will prevent any anchoring cement from flowing into the inner hole during the final step of probe installation.

8. Place the completed probe into the outer hole. The probe tubing should not contact the sub-slab material and the top of the female connector should be flush with the surface of the slab and centered in the outer hole. If the top of the completed probe is not flush with the surface of the slab, due to the outer hole depth being greater than 1⅜ inches, additional modeling clay may be placed around the stainless steel tubing adjacent to the nut that connects the stainless tubing to the female connector. Use a sufficient amount of clay to raise the probe until it is flush with the surface of the slab while ensuring that a portion of the clay will still contact and seal the inner hole.

9. Mix a small amount of the anchoring cement and use it to fill the space between the probe and the outside of the outer hole. Allow the cement to cure according to manufacturer’s instructions before sampling.

7.2.2 Sampling Set-Up

1. Wrap one layer of Teflon thread tape onto the NPT end of the male connector (e.g., Swagelok SS-400-1-4, or equivalent).

2. Remove the ¼-inch hex socket plug from the female connector (e.g., Swagelok SS-400-7-4, or equivalent).

3. To ensure that the interior of the sampling probe has not been blocked by the collapse of the inner hole below the end of the stainless steel tubing, a stainless steel rod, ⅛-inch diameter, may be passed through the female connector and the stainless steel tubing. The rod should pass freely to a depth greater than the length of the stainless steel tubing, indicating an open space or loosely packed soil below the end of the stainless steel tubing. Either condition should allow a soil gas sample to be collected. If the probe appears blocked, the stainless steel rod may be used as a ramrod to attempt to open the probe. If the probe cannot be opened, it should be reinstalled or a new probe installed in an alternate location.

4. Screw and tighten the male connector into the female connector. Do not over tighten. Overtightening may cause the probe to break loose from the anchoring cement during this step or when the male connector is removed upon completion of the sampling event.

5. If a collocated sub-slab sample or split sample is desired, a stainless steel tee (e.g., Swagelok SS-400-3-4TMT, SS-400-3-4TTM or equivalent) may be used in place of the male connector.

6. Attach a length of ¼-inch OD Teflon tubing to the male connector with a nut.

The Teflon tubing is then connected to the sampling container or system to be used for the sample collection.

7. After sample collection, remove the male connector from the probe and reinstall the hex socket plug. It is recommended that the hex socket plug be wrapped with Teflon thread tap prior to re-installation. Do not over tighten the hex socket plug. If excessive force is required to remove the plug during the next sampling event the probe may break loose from the anchoring cement.

7.2.3 Repairing a Loose Probe

1. If the probe breaks loose from the anchoring cement while removing or installing the hex head plug or the male connector (e.g., Swagelok SS-400-14, or equivalent), lift the probe slightly above the surface of the concrete slab.

2. Hold the female connector (e.g., Swagelok SS-400-7-4, or equivalent) with the ¾-inch open wrench.

3. Complete the step being taken during which the probe broke loose, following the relevant instructions above, remembering not to overtighten the connections.

4. Push the probe back down into place and reapply the anchoring cement.

5. Modeling clay may be used as a temporary patch to seal around the probe until the anchoring cement can be reapplied.

7.3 Tedlar Bag Sampling

1. Sampling will take place at least 2 hours after construction to allow for equilibration, preferably 24 hours or more.

2. An amount of air equivalent to three times the volume of the soil gas well must be evacuated prior to sampling (Purge volume = 3πr2h, where r is the radius of the inner probe and connecting tubing, and h is the entire length of the sampling train). Connect a vacuum pump, hand pump or soil gas syringe to the sample probe using a section of Teflon tubing. If using a vacuum pump, calculate the required length of time to purge the required volume, turn on the pump and adjust the flow rate to 3.0 L/minute. The calculated volume of air is evacuated from the hole for the specified length of time, or extracted for the equivalent volume using a hand pump or soil gas syringe.

3. A leak test should also be performed by placing a shroud around the sample train and using a tracer gas (99.999% laboratory grade helium) to enrich the atmosphere within the shrouded sampling train. A vacuum should then be drawn on the sampling tubing at 150-160 mL/min rate and the vacuum exhaust monitored for helium using a helium detector that has been factory calibrated within the past year. Any leaks showing >10% of the ambient helium reading should be located and sealed before proceeding with sampling.

4. After evacuation and leak test, a PID/FID monitoring instrument is connected to the probe using a Teflon connector. Upon stabilization, the reading is recorded on soil gas data sheets.

5. Use the vacuum box and sampling train to collect the sample. The sampling train is designed to minimize the introduction or loss of contaminants due to adsorption and other factors. All parts used are either Teflon or stainless steel, and a vacuum is drawn directly to avoid contamination from the pumps.

6. Place the Tedlar bag inside the vacuum box, attach it to the sampling port and open the valve. The sample probe should be attached to the sampling port with Teflon tubing and a “Quick Connect” fitting.

7. Draw a vacuum around the outside of the bag, using a pump connected to the vacuum box evacuation port with Tygon tubing and a “Quick Connect” fitting. The negative pressure inside the box causes the bag to inflate, drawing the sample into the bag.

8. Break the vacuum by removing the Tygon line from the pump. Remove the bagged sample from the box and close the valve. Record the date, time, sample location ID, name of sampler and any other pertinent information on the sample bag label and on data sheets or in logbooks.

9. Bags should not be labeled directly with a marker or pen, nor should adhesive labels be affixed directly to the bags. Inks and adhesive may diffuse through the bag material and contaminate the sample. Labels should be tied to the metal eyelets provided on the bags.

10. Chain-of-custody sheets must accompany the samples to the laboratory.

7.4 Summa Canister Sampling

1. Sampling will take place at least 2 hours after construction to allow for equilibration, preferably 24 hours or more.

2. An amount of air equivalent to three times the volume of the soil gas well must be evacuated prior to sampling (Purge volume = 3πr2h, where r is the radius of the inner probe and connecting tubing, and h is the entire length of the sampling train). Connect a vacuum pump to the sample probe using a section of Teflon tubing. Turn on the pump and adjust the flow rate to 3.0 L/minute. The calculated volume of air is evacuated from the hole by pulling a vacuum through the probe for the specified length of time.

3. A leak test should also be performed by placing a shroud around the sample train and using a tracer gas (99.999% laboratory grade helium) to enrich the atmosphere within the shrouded sampling train. A vacuum should then be drawn on the sampling tubing at 150-160 mL/min rate and the vacuum exhaust monitored for helium using a helium detector that has been factory calibrated within the past year. Any leaks showing >10% of the ambient helium reading should be located and sealed before proceeding with sampling.

4. After evacuation and leak test, a PID/FID monitoring instrument is connected to the probe using a Teflon connector. Upon stabilization, the reading is recorded on soil gas data sheets.

5. Attach a certified clean, evacuated 6-L Summa canister via the ¼-inch Teflon tubing.

6. Open the valve on the Summa canister. The soil gas sample is drawn into the canister by pressure equilibration. The approximate sampling time for a 6-L canister is 20 minutes.

7. Sample number, sample location, date collected, sampler name and any other pertinent sample information must be recorded on a chain-of-custody form and on a blank tag attached to the canister.

8. Chain-of-custody sheets must accompany the samples to the laboratory.

8.0 CALCULATIONS

Calculations used to determine concentrations of individual components are beyond the scope of this SOP.

9.0 QUALITY ASSURANCE/QUALITY CONTROL (QA/QC)

9.1 Sample Probe Contamination

Sample probe contamination is checked between each sample by drawing ambient air through the probe using a vacuum pump and checking the response with a PID/FID. If readings are higher than background, replacement or decontamination is necessary. Sample probes may be decontaminated simply be drawing ambient air through the probe until the PID/FID reading is at background. Contamination can also be removed by decontaminating with alconox and deionized water, then air drying. For persistent contamination, use of a portable propane torch may be needed. Using a pair of pliers to hold the probe, run the torch up and down the length of the sample probe for approximately 1-2 minutes. Let the probe cool before handling. When using this method, make sure to wear gloves to prevent burns. Having more than one probe per sample team will reduce lag times between sample stations while probes are decontaminated.

9.2 Sample Train Contamination

The Teflon line forming the sample train from the probe to the Tedlar bag should be changed on a daily basis. If visible contamination (soil or water) is drawn into the sampling train, it must be changed immediately. When sampling in highly contaminated areas, the sampling train should be purged with ambient air, via a vacuum pump, for approximately 30 seconds between each sample. After purging, the sample train can be checked using a PID/FID to establish the cleanliness of the Teflon line.

9.3 PID/FID Calibration

The PID and/or FID must be calibrated at least once a day using appropriate calibration gases.

9.4 Trip Blanks

A trip blank detects any sample contamination during shipping and storage. With the exception of Summa canisters, the trip blank is prepared and added to the site samples after sampling has been completed and prior to shipment.

9.4.1 Tedlar Bags

Each cooler containing Tedlar bag samples must contain one Tedlar bag of ultra-zero grade air, acting as a trip blank for samples shipped to a laboratory. Chain-of-custody records must accompany each cooler of samples and should include the blank that is dedicated to that cooler.

9.4.2 Summa Canisters

Canister trip blanks are evacuated containers that are shipped to and from the site with the canisters used for air sampling.

9.5 Field Blanks

Field blanks detect sample contamination during the handling and shipping process associated with a specific sampling event.

9.5.1 Tedlar Bags

For each day of sampling, a Tedlar bag is filled with ultra-zero air at the beginning of the day. This field blank is handled in the same manner as the samples.

9.5.2 Summa Canisters

For each day of sampling, a Summa canister is filled with ultra-zero air at the beginning of the day. This field blank is handled in the same manner as the samples, including .

9.6 Trip Standards

If Tedlar bags are used for sampling, each cooler containing samples should contain a Tedlar bag of standard gas to calibrate the analytical instruments. This trip standard will be used to determine any changes in concentrations of the target compounds during the course of the sampling day (e.g., migration through the sample bag, degradation, or adsorption). A fresh trip standard must be provided and placed in each cooler pending additional sample collection. Chain-of-custody records must accompany each cooler of samples and should include the trip standard that is dedicated to that cooler.

9.7 Lot Blanks

9.7.1 Tedlar Bags

Prior to use, one bag is removed from each lot of Tedlar bags to be used for sampling and checked for possible contamination as follows: Fill the test bag with ultra-zero grade air; withdraw a sample from the bag and analyze using a field portable GC or other field instrument to ensure sample container cleanliness prior to the start of the sampling effort.

9.7.2 Summa Canister Check

From each lot of four cleaned Summa canisters, one is used for a GC/MS certification check. If the canister passes certification, it is re-evacuated and all four canisters from that lot are available for sampling. If the chosen canister is contaminated, the entire lot of four Summa canisters must be re-cleaned and a single canister is re-analyzed by GC/MS for certification.

9.8 Duplicate Samples

A minimum of 5% of all samples should be collected in duplicate. The Project Manager will choose which samples to duplicate, typically in areas of highest concern. However, a duplicate may be taken only if after filling the first Tedlar bag and evacuating the well for 15 seconds, the second field monitoring device is within 20% of the first reading.

9.9 Spikes

A Tedlar bag spike and sorbent tube spike may be desirable in situations where high concentrations of contaminants other than the target compounds are found to exist (e.g., landfills). The additional level of QA/QC attained by this practice can be useful in determining the effects of interferences caused by these non-target compounds. Summa canisters containing samples are not spiked.

10.0 DATA VALIDATION

Data validation requirements set forth in the site-specific SAWP or Quality Assurance Program Plan (QAPrP) shall be adhered to for any given project. Results of quality control samples will be evaluated for contaminants. This information will be utilized to qualify the environmental sample results in accordance with the project's data quality objectives as set forth in the site-specific SAWP and/or QAPrP. However, for each target compound to be considered valid, the concentration found in the sample must be greater than three times the level of that compound found in the appropriate blank (lot, field and trip) that accompanied that sample. Additional data to be verified/validated include but is not limited to location information, GPS coordinates, digital photographs and area sketches.

11.0 HEALTH AND SAFETY

OSHA regulations should be adhered when working with potentially hazardous materials.

Personnel performing environmental work at OER sites should have their 40 Hour Hazardous

Waste Operations and Emergency Response (HAZWOPER) with 8 Hour refreshers as appropriate. Some level of Personal Protective Equipment (PPE) is generally required for all sampling and decontamination activities. The appropriate level of PPE for these activities may be found in the site-specific SAWP and/or the Site Health and Safety Plan (HASP). Personnel should adhere to the safety requirements outlined in the site-specific plans. The following is a summary of just some of the hazards associated with well sampling:

Exposure to unknown contaminants Lifting injuries associated with moving equipment, coolers with samples.

Heat/cold stress as a result of exposure to extreme temperatures and the use of PPE Slips, trips, and fall hazards

Biological hazards such as insects, snakes, spiders and poison ivy

Below surface pipes and rebar

Safety data sheets (SDS) should be readily available on-site for all decontamination solvents or solutions, as well as known site contaminants of potential concern, as required by the Hazard Communication Standard requirements set forth in the OSHA regulations. Investigation derived waste (IDW) generated from decontamination activities requires proper handling, storage, and disposal. Refer to the site-specific SAWP for IDW procedures.

12.0 REFERENCES

Guidance for Preparing Standard Operating Procedures (SOPs), EPA QA/G-6, US EPA, Office of Environmental Information, April 2007

Hayes, H.C., D.J. Benton, S. Grewal, and N. Khan. 2005. A Comparison between EPA Compendium Method TO-15 and EPA Method 8260B for VOC Determination in Soil Gas. Paper #46. AWMA Symposium on Air Quality Measurement Methods and Technology.

Hers, I., P. Jourabchi, M. Lahvis, P. Dahlen, E. H. Luo, P. Johnson, G. E. DeVaull, and K. U.

Mayer. 2014. Evaluation of seasonal factors on petroleum hydrocarbon vapor biodegradation and intrusion potential in a cold climate. Ground Water Monitoring & Remediation 34(4): 60- 78.

Johnson, P. C., and R. Deeb. 2014. GRACast series on vapor intrusion, Part 2, vapor intrusion:

lesson-learned from four years of intensive monitoring of a house over a dilute chlorinated solvent plume. Webcast, Groundwater Resources Association of California.

Luo, J., P. Dahlen, P. C. Johnson, T. Peargin, and T. Creamer. 2009. Spatial variability of soil-gas concentrations near and beneath a building overlying shallow petroleum hydrocarbon-impacted soils. Ground Water Monitoring & Remediation 29(1) Winter: 81-89.

USEPA Environmental Response Team. 2001. Standard Operating Procedures. Soil Gas Sampling. SOP 2042. https://response.epa.gov/sites/2107/files/2042-R00.pdf

USEPA. 2010. Temporal variation of VOCs in soils from groundwater to the surface/subslab.

EPA/600/R-10/118. October. Clu-in.org/download/contaminantfocus/vi/VI_APM-349_EPA- 600-R-10-118.pdf.

USEPA. 2015. OSWER Technical Guide for Assessing and Mitigating the Vapor Intrusion Pathway from Subsurface Vapor Sources to Indoor Air. OSWER Publication 9200.2-154.

https://www.epa.gov/sites/production/files/2015-09/documents/oswer-vapor-intrusion-technical-guide-final.pdf.

https://www.epa.gov/sites/production/files/2015-09/documents/oswer-vapor-intrusion-technical-guide-final.pdf https://www.epa.gov/sites/production/files/2015-09/documents/oswer-vapor-intrusion-technical-guide-final.pdf