Vacuum monitoring is typically conducted from the existing groundwater monitoring well network. Existing groundwater monitoring wells may not be sufficiently close to one another to adequately measure the vacuum distribution; therefore, temporary vacuum monitoring probes or permanent monitoring points may need to be installed.

The following standards apply:

• Existing monitoring wells should have grout seals and surface caps in good condition to prevent air leakage which might hinder measurement of small vacuum pressures.
• The radial distribution and minimum number of vacuum monitoring points required (including both wells and probes) will depend upon subsurface conditions. For a relatively homogeneous site, a minimum of three vacuum monitoring points are required. Heterogeneous sites should be monitored with a greater number of vacuum points, especially close to the extraction well.
• At least one monitoring well or point is required close to the extraction well and at least one monitoring point is required near the expected zone of influence. A third monitoring point is required within the zone of influence.
• For relatively homogeneous subsurface conditions, vacuum should be measured in wells and probes at nearly the same depth as the unsaturated screened interval of the extraction well(s).
• For highly heterogeneous subsurface conditions, or when three dimensional computer modeling is planned (i.e., significant vertical pressure gradients exist), vacuum should be measured at various depths.

Standard Air Permeability Test Procedures:

• Measure the background vapor VOC headspace readings in the extraction well prior to the pilot scale test. Background methane (CH₄) can also be measured prior to the test to help evaluate anaerobic degradation conditions.
• Measure the flow rate of extraction and VOC of extracted vapors at the extraction wellhead. One air sample must be taken for laboratory analysis. Measurements need to be taken upstream of any air dilution valves. If multiple extraction wells are tested concurrently, the flow rate and VOC concentrations need to measured at the manifold (i.e., prior to blower) to evaluate pipe head losses and total emissions.
• The temperature of the extracted air should be measured concurrently with flow rate measurements during testing.
• Measure vacuum influence in the surrounding soil probes and/or monitoring wells.
• If biodegradation potential is to be evaluated to optimize for bioventing, samples taken from soil vapor monitoring points (both wells and/or probes) should be measured for O₂ and CO₂ prior to inducing air flow and immediately after completion of the permeability test.

Miscellaneous Components of Air Permeability Tests:

• Muffler: need for a muffler depends on the size of equipment used during testing and the potential for public nuisance conditions.
• Off-gas treatment: the AQD might require off-gas treatment (usually GAC) during pilot tests, depending on anticipated emissions during testing. Contact the AQD at (307)777-7391 prior to performing tests.
• Water trap and/or particulate filter: may be needed.

Reporting Air Permeability Test Results:

• A site map drawn to scale indicating:

Locations of air extraction well(s) and vacuum measuring points. Paved areas, buildings, and structures that may act as surface seals or infiltration barriers. Buried utility trenches or other subsurface structures that may act as zones of increased permeability.

• Descriptions of field equipment and procedures used during testing.
• Table of operating flow rates at different vacuum steps, vacuum measured at monitoring points and duration of each vacuum step applied. Barometric pressure readings should also be tabulated. Times of readings should be included.
• Plot of soil vapor vacuum vs. horizontal distance from the extraction well to determine the zone of influence. Graph should be plotted on semi-log paper with vacuum as the log scale (y-axis). A linear regression analysis should be performed on the data.
• Table of VOC levels in extracted vapors (measured prior to any off-gas treatment system), temperature of extracted vapor, and time of each reading. Average VOC mass removal rates for the test must be calculated from extraction concentrations and flow rates for each vacuum step.
• Table of O₂, CO₂, and CH₄ measurements (when bioventing is considered), taken prior to and after conducting the air permeability test.
• Sampling methods and procedures.
• Boring logs and 'as-built' construction diagrams for air extraction well(s) and vacuum monitoring wells/points.

Air permeability test results are usually submitted with the full-scale system design application.

IN SITU RESPIRATION TEST FOR BIOVENTING

In addition to the pilot test described above, additional tests must be conducted at sites where bioventing is to be optimized over volatilization. In situ respiration studies are needed to determine the oxygen transport capacity of the soils and to estimate the biodegradation rates under field conditions. The test involves short term injection of air or an air/inert gas mixture into a well or monitoring probe that is screened in the contaminated soil. Carbon dioxide, oxygen, and inert tracer gas (typically helium, when used) concentrations are measured in the injection well/probe periodically for one to five days. The measurements are then compared to baseline concentrations of the gases prior to injection. Baseline measurements are taken at the injection point and at a well/probe located in uncontaminated soils. Increases in carbon dioxide and/or decreases in oxygen concentrations are indications of microbial activity in soils surrounding the injection point. Although the use of an inert tracer gas is not required, it is highly recommended since it provides baseline information on air diffusion rates and confirms that no system leaks are present.

Laboratory microbial screening tests are used to corroborate the presence of naturally occurring bacteria capable of degrading contamination present on site. These tests are generally not required since microbial activity can usually be detected during respiration tests. If the bacteria that degrades the contaminant in question is not typically found in the native soils, laboratory tests may be warranted to ascertain the feasibility of bioventing technology.

Guidelines regarding standard practices for the design and implementation of in situ respiration tests are presented below. Adherence to these guidelines should improve the overall quality of data obtained during respiration tests, although deviations may be warranted depending on site specific conditions.

In Situ Respiration Test Design Recommendations:

Air Injection Wells/Probes: Monitoring probes are the preferred type of air injection points and are typically installed in highly contaminated soils. However, an existing monitoring well can be used if a significant portion of the screened interval is above the water table. The following standards apply (also refer to GPC Guideline, "Minimum Content Requirements: Sub-Surface Investigation (SSI) Work plans," for additional minimum standards and conditions for monitoring wells:

• Generally, air should be injected into the test well(s)/probe(s) over a 24 hour period at rates ranging from 1.0 cubic feet per minute (cfm) to 1.7 cfm (60 cubic feet per hour to 100 cfh). Sufficient air should be injected in order to avoid boundary effects from interfering with test results.
• If helium is used as a tracer it must be 99% pure. When used, the flow rate of helium should be generally adjusted from 0.6 cfh to 1.0 cfh in order to obtain 1%-2% helium in the final air mixture injected.
• If a well is used for injection and the screened interval is greater than 10 ft, the required air injection rate may be too high to allow for helium injection.

In Situ Respiration Test Monitoring Requirements:

• Prior to beginning the test, sample injection well(s) and probe(s) for O₂, CO₂, CH₄ and VOC's.
• Prior to beginning the test, sample background well and probe located in uncontaminated soil for O₂ and CO₂.
• Measure pressure and flow rate during air injection.
• After air injection and helium injection (when used) is complete (i.e., 24 hours following start of injection), begin periodic monitoring of O₂, CO₂, and helium. Typically measurement of the soil gas should be conducted at ½, 2, 4, 6, and 8 hours and then every 4 to 12 hours, depending on the rate at which the oxygen is utilized. If oxygen uptake is rapid, more frequent monitoring is required. The actual frequency should be selected in the field so that the data collected shows a definite trend in O₂ and CO₂ concentrations to compensate for the scatter caused by measuring errors.
• There is a risk of pulling in atmospheric air during the process of purging and sampling at shallow monitoring points. When sampling shallow points, care should be taken to minimize the volume of air extraction. Low extraction rates should be maintained (i.e., 5 - 10 liters/minute).
• Monitoring should be terminated when the oxygen level is near background conditions or after 5 days of sampling.

Reporting In Situ Respiration Test Results:

• A site map drawn to scale indicating location(s) of air injection well(s)/probe(s).
• Descriptions of field equipment and procedures used during testing.
• Sampling methods and procedures.
• Boring logs and construction diagrams for air injection well(s) and probe(s) and background well/probe in uncontaminated zone.
• O₂ and CO₂ concentrations measured in background well.
• O₂, CO₂, CH₄ and VOC's measured in injection well(s) and probe(s) prior to injection.
• Table of injection flow rate and pressure including the time of each reading.
• Table of O₂ and CO₂ concentrations including time elapsed.
• Plot of %O₂, %CO₂ and %helium (when used) vs. time.

In situ respiration test results are usually submitted with the full scale system design application.

FULL SCALE SVE DESIGN

The field data obtained from the air permeability test is evaluated to determine or select the following:

1) The air permeability of the site, including the relationship between horizontal and vertical permeability.

2) The number and location of extraction points needed to achieve required air flow distribution in the contaminated subsurface areas.

3) The appropriate type and size of extraction blower/vacuum pump.

4) The appropriate air treatment technology, if required (approved by AQD).

Full scale SVE system design can be done with the aid of computer modeling for large or complicated projects, or done with an empirical analysis using pilot scale data without modeling for smaller or more simple projects. The use of air flow and multi phase transport models allows for a more proficient choice of design parameters such as extraction well locations and air flow velocities. Empirical design methods relying only upon pilot test results generally yield lower confidence levels that remedial goals will be achieved.

Design considerations and recommendations, along with SVE system installation and operation suggestions, are presented below. It is important to note that all of the information previously presented regarding the implementation of an air permeability test is also relevant to full scale systems.

General Design Considerations/Recommendations:

• In a heterogeneous, mixed lithology site, the zone of influence of more permeable layers is augmented by overlying less permeable layers (i.e., silts and clays). Removal rates may decline rapidly after the coarse grained layers are remediated because extraction is limited by VOC removal rates from the fine grained soils. For this reason, it is extremely important to tailor the design for the natural geologic conditions.
• As a rule of thumb, the zone of influence is considered to be the distance from the extraction well at which a vacuum of at least 0.1 inches of water is observed. For sites with contaminated areas of stratified geology, design zones of influence should be defined for each geologic strata.
• Vacuum and air flow rates: full scale system values are based on vacuum and air flow rates measured during pilot test. If multiple geologic strata are evaluated during the air permeability test, the achievable air flow rate per foot of screen should be considered and/or the air permeability of each geologic unit.

System Configuration and Components:

Extraction Well Placement and Construction:

• Since vacuum propagation and air velocity decrease significantly with distance, an extraction well configuration employing a highly overlapping zone of influence (ZOI) design is favorable. The remediation of the contamination should progress much quicker than when less conservative well spacings (i.e., only slightly overlapping ZOIs) are chosen. Although, care should be taken to not locate wells too close together and cause "short circuiting".
• Use closer well spacing in highly contaminated areas to increase mass removal rates.
• At sites with stratified soils, wells that are screened in strata with low intrinsic permeability's should be spaced more closely than wells that are screened in strata with higher permeability's.
• If the K_h/K_v ratio is very high, or if a surface seal exists or is planned for the site, the wells may be spaced farther apart because air is drawn from a greater lateral distance and not directly from the land surface.
• When the water table is shallow (< 10 ft), relatively close well spacing may be necessary if vertical wells are used.
• If homogeneous soil conditions prevail, ensure that the well is screened throughout the entire zone of contamination.

Manifold Piping:

• Slope the manifold piping towards the extraction wells so that condensate or entrained groundwater will drain toward the well.
• If the system is to be operated on a long-term basis and during winter months, winterization provisions are required (e.g., bury manifolding below frost line, etc.).

Blower or Vacuum Pump:

• In applications where explosions might occur, blowers must have explosion proof motors, starters, and electrical systems.
• A discharge muffler is required in situations where public nuisance conditions might arise.
• Blowers must be protected from suction of water and particulates by using in-line filters and moisture knockouts. Accumulated water may require treatment prior to disposal.

SVE Instrumentation/Flow Measuring Equipment:

• A vane type meter calibrated from 3 to 30 scfm is recommended for low flow rates. A rotameter may also be appropriate for low flow. Orifice plate recommended for measuring higher flow rates. Averaging picot tube recommended for measuring very high flow rates.

Optional SVE Components/Modifications:

• Injection and passive inlet wells: often used at sites where deep (> 25 ft) contamination is targeted or where soils to be remediated are isolated from the atmosphere by low permeability materials. Passive wells have little effect unless they are placed close to the extraction well. Injection wells are used to eliminate potential stagnation zones, but should not be placed such that the injected air will cause contaminants to migrate outward. Air injection should not be used if the temperature of the injected air is lower than normal soil temperature. Colder air may reduce the volatility of the contaminants.
• Horizontal extraction wells or trenches: used when shallow water table conditions exist (< 10 ft) and the zone of contamination is confined to the shallow stratigraphic unit. As with vertical well construction, the screen must be high enough above the groundwater table that normal fluctuations do not submerge the screen. Additionally, vacuum pressures should be sufficiently low to ensure that upwelling of groundwater will not occlude the well screen(s).
• Surface seals: may be included to prevent surface water infiltration, reduce fugitive vapor emissions, prevent vertical short-circuiting of air flow, or increase the design zone of influence. A higher vacuum applied at the extraction well may be required with a surface seal because of the resulting lower pressure gradients and decreased flow velocities. High density polyethylene (HDPE) liners, clay or bentonite seals, concrete, or asphalt paving are used as surface seals. Existing covers, such as concrete or asphalt, might not provide sufficient air confinement if they are constructed with a porous subgrade material.
• Groundwater depression pumps: groundwater pumping may be necessary in situations where groundwater table is shallow or when smear zone soils are targeted. At sites where significant water table elevations have occurred (i.e, seasonal variations), groundwater pumping may be needed to insure effective year-around operations of the remediation system. Pumped groundwater may contain significant amounts of dissolved contamination, requiring treatment prior to disposal. If large quantities of groundwater have to be pumped to achieve the desired level of dewatering, lowering the groundwater table may not be cost effective because of the treatment of pumped water. Other remedial alternatives may be more appropriate.
• Soil fracturing: applying hydraulic fracturing or jet assisted fracturing to fine grained soils can greatly increase the air permeability and therefore enhance the volatilization process. The fractures are filled with sand or other porous materials which serve as proppants and provide a matrix for contaminant degrading microbes in bioventing applications. It is important to note that some of these techniques are patented.

Calculation/Modeling Recommendations:

• Complicated projects (i.e., heterogeneous and mixed lithology, subsurface structures, large remediation systems, etc.) may require computer modeling to effectively design the full scale SVE system.
• When surface leakage conditions exist, a Hantush analysis should be performed using pilot scale data.
• For non-leaking conditions (e.g., impermeable seal at surface), a Theis analysis should be performed using pilot scale test data.

FULL SCALE BIOVENTING DESIGN

The data obtained from both the air permeability test and the in situ respiration test is evaluated in order to design a bioventing system. The most important design parameter is maintaining an adequate oxygen supply in the contaminated soils in order to sustain aerobic biodegradation. Design considerations and recommendations, along with system installation and operation suggestions, are presented below. It is important to note that all of the information presented previously regarding the implementation of permeability and respiration tests is also relevant to the full scale system.

General Design Considerations/Recommendations:

• The slope of the data (i.e., %O₂, %CO₂ and %helium vs. time) can generally be analyzed using a zero order relationship to determine the linear decay rate.
• As a general guide, when helium is used as a tracer during respiration tests, a fractional helium loss of 0.4 or less over 100 hours is acceptable and the data can be considered reliable (i.e., no short circuiting is occurring).
• Due to the buffering capacity of alkaline soils and adsorption to soil moisture, the relationship between contaminant aerobic biodegradation and CO₂ production is not always a reliable indicator.
• Design of a bioventing system must account for the differing zones in order to optimize the distribution of oxygen throughout the contaminated zone. The air zones within soils can be: 1) replenished frequently, 2) replenished infrequently (aerobically dormant), or 3) largely static and accumulating anaerobic fermentation products such as methane.
• In bioventing, the zone of influence is an estimate of the maximum distance from an extraction/injection well at which sufficient air flow can be induced to sustain acceptable degradation rates. For sites with stratified geology, the design zone of influence should be defined for each soil type.
• Bioventing air flow rates are typically an order of magnitude lower than SVE systems in order to accomplish maximum oxygen usage by the vadose zone microbial populations.

System Configuration and Components:

Injection/Extraction Well Placement and Construction:

• When air injection wells are proposed without accompanying extraction wells, the design must ensure that contaminants do not migrate into subsurface structures such as basements.
• As with SVE systems, when extraction wells are proposed the design must ensure that water table upwelling or seasonal fluctuations do not occlude well screens.
• In areas of high contaminant concentrations, closer well spacing is necessary to increase oxygen flow and accelerate contaminant degradation rates.
• In stratified soils, well spacings may be irregular. Wells screened in zones of lower air permeability must be spaced closer together than wells screened in zones of higher permeability.
• If homogeneous soil conditions prevail, ensure that the well is screened throughout the entire zone of contamination.

Manifold Piping and Blower/Vacuum Pump:

• Same as Full Scale SVE Design.

Optional Bioventing Components:

• Same as Full Scale SVE Design.

DESIGN REPORT FOR SVE AND BIOVENTING

General Requirements:

• Discussion/justification of system design with a description of the systems' capabilities for remediating the soil at the site.
• Engineering calculations for determining well spacing, including zone of influence measurements from air permeability test and respiration rate analysis for bioventing. Clearly state all assumptions. Legible, hand written calculations are acceptable. Include references for formulas used.
• If any computer modeling is used, include model assumptions and results.
• If a water trap or groundwater pumping is proposed, discuss the need for treating extracted water. If treatment is required, describe technology to be used. See WQD Rules and Regulations Chapter XI, Sections 6 and 7, for more information regarding permit application requirements for wastewater treatment.
• Brief description of off-gas treatment proposed (when treatment is required by AQD).
• Submit winterization provisions (Continuous year-round operation may likely be required).
• Design drawings must be scaled to show sufficient detail.

Plan View:

Scaled site map illustrating and identifying:

• Contaminated area to be remediated (dissolved iso-concentration contours and free product thickness contours).

Note: Product thicknesses may be difficult to contour in very low permeability (fine grained) or fractured consolidated subsurface conditions. Please indicate product thickness at monitoring well locations.

• Potentiometric surface.
• Location of proposed and existing extraction/injection wells and monitoring points/wells.
• Zone of influence of each extraction well.
• Location of manifold, blower and other equipment.
• Subsurface structures present (i.e., underground utilities, etc.).
• Paved areas, buildings and surface structures present. Include residential areas and locations where basements may be present.
• Paved or sealed surface areas.
• Aboveground surface seals (if proposed).

Process and Instrumentation Schematic:

• Process flow diagram indicating all components and direction of air/water flow through system components.

Profile Views and Cross Sections:

• Typical monitoring well/point cross section construction detail: one cross section is sufficient for all wells constructed in the same manner.
• Representative hydrogeologic cross sections: profile view of the zone of highest contamination illustrating and identifying elevations of ground surface, boundaries between differing lithologies and/or permeability's, water table, screened interval of extraction wells lying in cross section, and analytical soil sampling results at respective depths.

Specifications:

• Size and type of blower/vacuum pump including range of operating flow rates, manufacturers performance curves, and vacuum levels.
• Piping specifications including sizing and compatibility of piping materials with contaminants.
• Maximum flow ratings for activated carbon units, oil-water separators, or other treatment units proposed.
• Specifications of measuring instruments including vacuum and flow gauges.

SVE AND BIOVENTING OPERATION AND MONITORING

Operation and Maintenance Manual:

The efficiency and reliability of an SVE or bioventing system is largely dependant on system design; however, adequate maintenance becomes the critical factor once a system is operational. For this reason an Operation and Maintenance (O&M) Manual must be submitted for review. A general outline representing the minimum information required in an O&M manual can be found in Appendix C of GPC Guideline #2.

In addition to the outline, the following issues must also be described in detail within the O&M manual:

• The requirements of the Division of Occupational Health and Safety (OSHA) must be met during construction, installation, and operation of the remediation system. For more information call (307) 777-7786.
• A Health and Safety Plan (HASP) and/or a Spill Prevention, Control, and Countermeasures (SPCC) Plan may need to be submitted to meet federal requirements.

As-Builts

The 'as-built' construction information is due along with the first monitoring report (see performance monitoring below) approximately 60 days after system startup. The 'as-built' submittal should include the following:

• Any deviations from the plans and specifications in the design report.
• Complete 'as-built' construction drawings and specifications.

Performance Monitoring Plan:

A Performance Monitoring Plan (PMP) must be submitted prior to issuance of the Permit to Construct. Following WQD's approval of the PMP, it should be included in the O&M manual. The PMP should include at a minimum:

• SVE: Proposed monitoring frequency for air flow rates, vacuum and VOC concentrations.
• Bioventing: Proposed monitoring frequency for flow, vacuum, VOC, O₂ and CO₂.
• Descriptions of analytical methods and sampling procedures.
• Proposed frequency of reporting.

Monitoring of remedial progress for bioventing systems is more difficult than for SVE systems in that mass removal rates cannot be directly measured in extracted vapors. Both VOC concentrations and CO₂ concentrations should be monitored. Systems employing only injection wells have limited capability for performance monitoring because of the impossibility of collecting off-gas. The monitoring plan may need to include subsurface soil sampling to track constituent reduction and biodegradation conditions. Final clean-up approval will require soil sampling to verify effectiveness of bioventing.

SVE and Bioventing Monitoring Recommendations:

Note: These recommendations are general guidelines and significant variations may be warranted or required depending on site specific characteristics.

Vacuum Monitoring Recommendations:

• Daily monitoring of operating vacuum at blower inlet for first week, weekly for first month. System operating vacuum monitored at least monthly after startup.
• Vacuums should be measured at individual extraction wells at startup. If the system operating vacuum or the vacuums in surrounding monitoring wells or points changes significantly, the individual extraction well vacuums need to be rechecked.
• For SVE, vacuums of surrounding monitoring wells or points should be recorded with same frequency as air permeability test during the initial startup of the full-scale system (typically at 15 minute intervals for 1-2 hours, and weekly for first month) to verify the zone of influence estimates. The vacuums shall be measured at least monthly following the first month to verify that the zone of influence has not changed and that short circuiting or mechanical failures have not occurred.

Air Flow Monitoring Recommendations:

• Daily monitoring of total system air flow rate for first week, weekly for first month. System air flows measured at least monthly following first month.
• Monitoring of air flow rates at individual extraction wells at start-up. If system air flow rate significantly changes during subsequent operations, the air flow rate needs to be measured again at each well.

Notes:

1) Air flow rates need to be measured directly with a dedicated device, not estimated from blower performance curves.

2) Flow rate of individual wells in SVE systems need to be balanced to obtain nearly equivalent air flow rate and to maximize contaminant mass removal, not to achieve equivalent vacuums.

SVE Concentration Monitoring Recommendations:

• Daily monitoring of VOC concentrations in system effluent (prior to any off-gas treatment) performed with a portable meter, preferably with an FID, for first week, and weekly for the first month. VOC monitoring of system effluent should be performed at least monthly after startup, concurrently with air flow.
• Off-gas VOC composition sampling performed by analytical laboratory (BTEX, TPH analysis and other applicable parameters) shall occur at start-up, and at an acceptable frequency following start-up (if applicable, at least at the minimum frequency required by AQD).
• Monthly VOC field screening at individual wellheads following start-up.

Notes:

1) Air temperature should always be measured concurrently with VOC monitoring to enable the accurate calculation of the mass removal rates.

2) Flow rate of individual wells in SVE systems needs to be optimized to maximize the contaminant mass removal rate.

Bioventing Concentration Monitoring Recommendations:

• At least daily monitoring of VOC, O₂ and CO₂ concentrations in system effluent during system startup and weekly to bi-weekly after startup.

REFERENCES

Boulding, J.R., 1995. Practical Handbook of Soil, Vadose Zone, and Ground-Water Contamination: Assessment, Prevention and Remediation. CRC Press, Inc., Boca Raton, Florida.

Cookson, J.T., 1995. Bioremediation Engineering: Design and Application. McGraw-Hill, Inc., New York, New York.

Fetter, C.W., 1993. Contaminant Hydrogeology. Macmillan Publishing Company, New York, New York.

Freeze, R.A. and J.A. Cherry, 1979. Groundwater. Prentice-Hall, Inc., Englewood Cliffs, New Jersey.

Johnson, P.C., C.C. Stanley, M.W. Kemblowski, D.L. Byers and J.D. Colthart, 1993. "A Practical Approach to the Design, Operation, and Monitoring of In Situ Soil-Venting Systems." Ground Water Monitoring Review, Spring.

Norris, R.D., et al., 1994. Handbook of Bioremediation. CRC Press, Inc., Boca Raton, Florida.

Nyer, E.K. et al., 1996. In Situ Treatment Technology. CRC Press, Inc., Boca Raton, Florida.

Pedersen, T.A. and J.T. Curtis, 1991. Soil Vapor Extraction Technology. Noyes Data Corporation, Mill Road, Park Ridge, New Jersey.

U.S. EPA, 1993. "Decision Support Software for Soil Vapor Technology Application: HyperVentilate." EPA/600/R-93/028, February.

U.S. EPA, 1991. "Handbook: Stabilization Technologies for RCRA Corrective Actions." EPA/625/6-91/026, August.

U.S. EPA, 1994. "How to Evaluate Alternative Cleanup Technologies for Underground Storage Tank Sites: A Guide for Corrective Action Plan Reviewers." EPA/510/B-94/003.

U.S. EPA, 1993. "Presumptive Remedies: Site Characterization and Technology Selection for CERCLA Sites With Volatile Organic Compounds in Soils." EPA/540/F-93/048, September.

U.S. EPA, 1991. "Soil Vapor Extraction Technology Reference Handbook." EPA/540/2-91/003, February.

Water Science and Technology Board, Commission on Engineering and Technical Systems, National Research Council, 1993. In Situ Bioremediation: When does it work? National Academy Press, Washington, D.C.

APPENDIX A

APPENDIX B

GPC GUIDELINE #5 - Checklist #1: SVE Air Permeability Test and Detailed Evaluation of SVE Applicability

This checklist is intended to aid in reviewing proposals for conducting a detailed pilot test of an SVE system. The list also incorporates criteria to be reviewed after performing the pilot test in order to further evaluate the potential effectiveness of using SVE at a site. If the answer to several questions is no, modifications to the proposed testing procedures may be warranted or additional information should be requested.

GPC GUIDELINE #5 - Checklist #2: Administrative Checklist for SVE Design Report

This checklist is intended to aid in reviewing the design report and application materials for an SVE system. The list incorporates an evaluation of the system design as well as completeness of the application package.

GPC GUIDELINE #5 - Checklist #3: Air Permeability Test, In-situ Respiration Test and Bioventing Applicability

This checklist is intended to aid in reviewing proposals for conducting detailed pilot tests for a bioventing system. The list also incorporates criteria to be reviewed after performing the pilot tests in order to further evaluate the potential effectiveness of using bioventing. If the answer to several questions is no, modifications to the proposed testing procedures may be warranted or additional information should be requested.

GPC GUIDELINE #5 - Checklist #4: Administrative Checklist for Bioventing Design Report

This checklist is intended to aid in reviewing the design report and application materials for a bioventing system. The list incorporates an evaluation of the system design as well as completeness of the application package.