1.0 - State The Problem

2.0 - Identify the Decisions - "Prioritized and Logical Sequence for Actions"

3.0 - Identify Inputs

4.0 - Define Study Boundaries

5.0 - Develop a Decision Rule

6.0 - Specify Tolerable Limits for Decision Errors

7.0 - Optimize the Design for Obtaining Data

1.0 - Introduction

1.1   History/Background

Past operations have resulted in volatile organic compound (VOC) impact to soil, rock, and groundwater at CSSA. Results of groundwater sampling and analysis programs have identified that groundwater impacted by VOCs at concentrations exceeding Federal Safe Drinking Water Act, Maximum Contaminant Levels (MCLs) extends off-post and has impacted residential drinking water wells located along the southwestern boundary of CSSA. AOC-65 is suspected as a principal source area for the off-post groundwater plume.

The overall objectives of the program are to address groundwater contamination in the AOC-65 area. Specifically, the project is designed to investigate subsurface features that affect contaminant migration in the vadose/recharge zones and compare the use of soil vapor extraction as a remedial alternative to other applicable remediation technologies.

Parsons intends to achieve these objectives by executing a treatability study of contaminated media underlying Building 90 and from areas surrounding the suspected contaminant source area(s). Parsons will install soil vapor extraction wells and vapor monitoring points to conduct a soil vapor extraction treatability study. A surface geophysical study has been initiated and will be continued, as needed, to identify probable fractures in the upper formation to assist in the selection of well placement for the treatability study. Following completion of the treatability study, Parsons will prepare an evaluation of soil vapor extraction system to remediate volatile organic contamination remaining in vadose soils and fractured media, and will asses other potential technologies that may be applicable to enhancing remediation or expediting contaminant removal.

This data quality objective (DQO) document is focused on the remediation activities planned at AOC-65 and include vapor extraction well (VEW) installations, vapor monitoring point (VMP) installations, piezometer installations, soil vapor, soil, and groundwater sampling and analyses, and various other associated activities.

1.2   The AOC-65 Planning Team

1.2.1   CSSA

Mr. Brian Murphy, CSP, Environmental Officer, CSSA

Mr. Jeff Aston, US Army Corps of Engineers

Mr. Christopher Beal, Contract Geologist, Worldwide Performance and Innovation

1.2.2   Air Force Center for Environmental Excellence (AFCEE)

Ms. Teri DuPriest, Environmental Restoration Division

Mr. Edward Brown, Chemist, Environmental Restoration Chemistry

Mr. Joe Fernando, Contract Chemist, Portage Environmental

1.2.3   Parsons

Ms. Susan Roberts, Client Service Manager

Mr. Brian Vanderglas, TO 0058 Project Manager

Ms. Karuna Mirchandani, TO 0042 Project Manager

Mr. Gary Cobb, TO 0058 Task Manager (Geophysical Treatability Testing)

Mr. Ken Rice, TO 0058 Task Manager (Removal Action,& Data Management)

Mr. Scott Pearson, TO 0042 Task Manager

Ms. Kimberly Riley, Field Team, Community Relations Support

Ms. Tammy Chang, Project Chemist

Mr. Matt Wise, Field Team

Mr. Kyle Caskey, Field Team

Ms. Samantha Elliot, Field Team

Mr. Jonathan Skaggs, Field Team

1.3   The Decision Makers

Lieutenant Colonel Jason D. Shirley, Commander, CSSA

Mr. Brian Murphy, CSSA Environmental Office

Mr. Greg Lyssy, U.S. EPA, Region 6

Mr. Kirk Coulter, TNRCC, Corrective Action Section

2.0 - Identify the Decisions - �Prioritized and Logical Sequence for Actions� (Step 2)

2.1   Key Decisions

2.1.1   Determine preferred contaminant migration pathways.

2.1.2   Determine the locations and orientations of major structural features in upper 150 feet of formation underlying site (recharge zone).

2.1.3  Determine the relationships between major structural features and contaminant migration

2.1.4  Determine primary vapor migration routes and interconnectivity of fractures and jointing patterns, faults, and/or karst features identified within the area subsurface.

2.2   Regulatory Compliance Decisions

2.2.1   Verify that SVE system air emission concentrations do not exceed standard air exemption criteria

2.2.2  Determine whether additional pollution controls are required for the SVE system

2.2.3   Determine the waste classification of the various wastes generated during the program

2.2.3.1   Determine the waste classification for SVE system condensate.

2.2.3.2   Determine the waste classification for SVE system spent carbon.

2.2.3.3   Determine the waste classification of drill cuttings generated during the project.

2.2.3.4   Determine the waste classification of well purge liquids generated during the project.

2.2.3.5   Determine the waste classification of excavated materials generated during removal actions conducted for the project.

2.2.4   Quantify contaminant concentrations associated with soils forming the base and sidewalls of the excavation remaining in AOC-65 shallow soils after completion of soil removal actions for comparison to appropriate TNRCC accepted closure criteria.

2.3   Groundwater Recharge Decisions

2.3.1   Determine the appropriate locations and screened intervals for piezometers installed to monitor recharge through the upper unsaturated portion of the Lower Glen Rose Formation.

2.3.2   Determine the relationship between precipitation event frequency, duration, and intensity to measured precipitation infiltration, groundwater recharge, and percolation of groundwater through the vadose zone.

2.3.3   Determine the relationship between precipitation events to groundwater constituent concentration distribution and migration in vadose zone fractures.

2.3.4   Evaluate relationships between VOC and water levels in upper vadose zone piezometers to contaminant levels reported in wells constructed in the Lower Glen Rose water producing zones.

2.4   SVE Study Decisions

2.4.1   Establish baseline pre-treatability test groundwater constituent concentrations and concentration distribution.

2.4.2   Determine baseline soil gas concentrations.

2.4.3   Determine the locations of principal soil contamination source areas (targeted treatment areas).

2.4.4   Determine the relationship between soil gas concentration as a function of SVE various system operating parameters (flow rate, vacuum pressure, pulsing, etc.).

2.4.5   Determine the radius of influence (horizontal and vertical) associated with each VEW and identify impacts to the influence radius related to subsurface structural features and groundwater recharge interference.

2.4.6   Determine attainable contaminant mass removal rates from treatability test system and individual VEWs, as applicable.

2.4.7   Determine optimum system performance settings for a long-term vapor extraction system operation based on the treatability study results.

2.5   System Layout Decisions

2.5.1   Determine the appropriate locations and screened intervals for piezometers installed to monitor recharge through the upper unsaturated portion of the Lower Glen Rose Formation.

2.5.2   Determine appropriate locations, depths, and screened intervals for VEWs and
VMPs installed in support of the AOC-65 soil vapor extraction treatability study.

2.5.3   Determine the effectiveness of the vapor extraction system to treat the entire unsaturated zone, and identify areas/depth intervals where system expansion will significantly improve VOC removal rates.

2.6   Removal Action Decisions

2.6.1   Determine the lateral and vertical extent of impacted fill material beneath Building 90.

2.6.2   Determine the lateral and vertical extent of impacted soil outside Building 90 that may require removal, particularly in the drain lines/ditches outside Building 90.

2.6.3   Determine worst-case (during drilling or removal actions) indoor air VOC concentrations within Building 90.

2.7   Engineering Design Decisions

2.7.1   Determine the most effective post-remediation drainage routes over the pavement outside of the West side of Building 90.

2.7.2   Determine the anticipated volume of precipitation runoff from the building gutter system and the paved surface areas to the area culverts.

2.7.3   Determine whether the Building 90 gutters should be cleaned out to facilitate more efficient drainage from the Building roof to the desired drainage fields.

2.7.4   Determine whether an excavation event is required inside Building 90 for soils located beneath the building slab.

2.8   Future Decisions

2.8.1   Compare the differences in precipitation event frequency, duration, and intensity to measured precipitation infiltration, groundwater recharge, and percolation of groundwater from the vadose zone to measured groundwater recharge exhibited within deep wells within the area.

2.8.2   Assess the relationship between precipitation event frequency, duration, and intensity to groundwater constituent concentration distribution and migration observed in vadose zone fractures to relationships between precipitation event frequency, duration, and intensity to groundwater constituent concentration distribution and migration in area deep wells.

2.8.3   Determine the system design modifications (additional VEWs, targeted depth intervals, etc.) that would enhance the AOC-65 SVE system performance.

2.8.4   Determine whether additional pollution controls are required for long-term operation of the SVE system.

2.8.5   Determine appropriate operation and maintenance data collection needs to enable continued evaluation of system effectiveness and performance.

2.9   Alternative Decision

2.9.1 No action (No additional program activities).

3.0 - Identify Inputs (Step 3)

3.1   General Inputs

3.1.1   Conduct various geophysical investigation techniques to potentially include: electrical resistivity, microgravity, very low frequency electromagnetics, ground penetrating radar, and/or seismic reflection. Geophysical investigations shall be conducted on a grid pattern of sufficient size to yield the level of measurement detail required to support determining the locations, depths, sizes, and orientation of major structural features associated with the uppermost 150 feet of material present within the site subsurface.

3.1.2   Perform borings to validate the surface geophysical investigation findings through core sampling coupled with down-hole geophysical surveys to include a combination of borehole caliper logging, natural gamma logging, borehole radar, and other geophysical measurement techniques deemed appropriate.

3.1.3   Collect groundwater samples from each monitoring well/piezometer located within the AOC-65 area (within 500 feet of Building 90) and submit the samples for VOC and natural attenuation parameter laboratory analyses for baseline analysis.

3.2   Regulatory Compliance Inputs

3.2.1   Collect a sample of condensate liquid removed from the SVE system (contained within the knock-out drum) once the knock-out drum becomes half full and submit the sample for TCLP-VOC analytical testing using EPA SW-846 Method 8260b to determine waste disposal options.

3.2.2   Collect a sample of the spent carbon contained within the granular activated carbon (GAC) units installed as the air pollution control system for the Building 90 subslab vent and AOC-65 SVE treatability test systems once stack emissions suggest vapor breakthrough has occurred. Analyze the spent carbon samples for TCLP-VOCs using EPA SW-846 Method 8260b to determine waste disposal options.

3.2.3   Collect a nine-part composite sample of investigation derived drill cuttings after the drilling program associated with TO-0058 is completed. Submit the composite sample for VOC analysis using EPA SW-846 Method 8260b to determine waste disposal options.

3.2.4   Collect a sample of investigation derived groundwater purge fluids from within each purge fluid container and submit the sample for VOC analysis using EPA SW-846 Method 8260b to determine waste disposal options.

3.2.5   Collect a nine-part composite sample of excavated materials generated as the result of active soil removal actions implemented for the project. Submit the composite sample for VOC analysis using EPA SW-846 Method 8260b to determine waste disposal options.

3.3   Groundwater Recharge Inputs

3.3.1   Install a weather station adjacent to Building 90 to measure and record precipitation event frequency, duration, and intensity information.

3.3.2   Install and operate pore pressure transducer data loggers within each piezometer installed in close proximity to the weather station to measure changes in water levels over time. Pore pressure transducers will be programmed to record depth to water level referenced to the top of well casing at a frequency of at least once every four hours. Transducers will be of sufficient PSI rating and will be installed at proper depth intervals to minimize loss of water level data and damage to transducers due to significant groundwater recharge events.

3.3.3   Collect groundwater samples for VOC analysis from each of the area piezometers and monitoring wells at the initiation of the project to establish base-line conditions.

3.3.4   Collect groundwater samples for VOC analysis from area piezometers and monitoring wells at specified time intervals (24 hours, 48 hours, and 96 hours) following a significant rainfall event (greater than 1 inch).

3.3.5   Collect groundwater samples from within each of the vadose zone piezometers for VOC analysis and compare the results to groundwater sample VOC analytical results obtained within the deep wells of the area during activities conducted under TO � 0042.

3.4    SVE Study Inputs

3.4.1   Conduct soil gas screening to include total volatile hydrocarbons (TVH), oxygen, and carbon dioxide and soil gas analytical testing at each VEW and VMP prior to SVE test initiation and at selected time intervals (no greater than every 4 hours) during the SVE test.

3.4.2   Conduct soil gas airflow rate measurements at the SVE system main exhaust line during operation to facilitate calculating contaminant removal rates.

3.4.3   Monitor changes in soil gas oxygen, carbon dioxide and total volatile hydrocarbons (TVH) at each accessible VMP, VEW and piezometer prior to, and during, the treatability test to access interconnectivity.

3.4.4   Measure pressure responses at each of accessible piezometer, VEW and VMP when extracting from one VEW to assess interconnectivity.

3.4.5   Measure pressure responses at regular four-hour intervals during and following specific SVE testing phases at each of the VEWs and VMPs included within the analysis.

3.4.6   Measure soil gas flow rates at each VEW during active extraction to gather data needed to estimate contaminant mass removal rates from specific wells.

3.4.7   Collect soil gas screening samples from each, VMP, VEW, and piezometer to determine which intervals are appropriate for collection of VOC analytical data by (Method TO-14). Samples will be collected from up to 8 intervals for subsurface VOC testing prior to starting the SVE system, and then periodically during operation of the SVE system.

3.4.8   Collect soil gas samples from the SVE stack (post-GAC) and from the pipeline (pre moisture separator) for VOC analytical testing fifteen minutes after the initial system start-up.

3.4.9   Collect soil gas samples from each extracting VEW after 1-hour, 8-hours, 24-hours, 48-hours, 4 days, and possibly 8 days of operation for VOC analytical testing using EPA analytical method TO-14. This cycle will be repeated on at least three different configurations or extraction wells. Depending on the results from the first testing cycle, a different sampling schedule may be required to either stretch out the testing to a maximum or 30 days, or to condense the sampling into the first four days.

3.5   System Layout Inputs

3.5.1   Conduct organic vapor screening analyses for each continuous five-foot soil/rock sample interval obtained from the deepest piezometer boring installed for the program.

3.5.2   Conduct at least one discrete soil gas sample packer testing for up to eight specific stratigraphic intervals within the deepest boring drilled in support of the piezometer installation and VEW/VMP installation program. Soil gas samples will be collected for each of the specific packer tests and submitted for VOC analytical testing using EPA analytical method TO-14.

3.5.3   Evaluate lithologic logs relative to geophysical survey predicted subsurface features prior to initiating drilling at each subsequent borehole to ensure that all data collected to date is considered when selecting the next VEW, VMP, or piezometer location and screened intervals.

3.6   Removal Action Inputs

3.6.1   Collect surface soil samples representative of soil materials forming the excavation base and sidewalls and submit these samples for VOC analysis using EPA SW-846 Method 8260b. The number of required samples is a function of the size and shape of the removal action excavation as approved by TNRCC. Excavation activities will continue for areas where soil sample analytical results identify residual soil concentrations exceeding Tier 1 Industrial soil protective concentration limits (PCLs) established for protection of groundwater associated with a Class 1 aquifer assuming a 1/2-acre source area.

3.6.2   Collect indoor air samples from the central portion of Building 90 at the normal breathing zone height (five feet above the building slab) on a once per day basis for the first three days of the subslab vent system operation for VOC laboratory testing using EPA analytical method TO-14.

3.6.3   Conduct indoor air quality TVH concentration screening every four hours for the first three days of operating the Building 90 subslab vent system. Indoor air quality screening will be performed using the typical 15-point building indoor air screening method utilizing a photo-ionization detector.

3.7   Engineering Design Inputs

3.7.1   Conduct soil sampling activities, utilizing hollow stem auger/split spoon drilling and sampling techniques, at twelve boring locations inside Building 90 and at twelve locations along surface drainage features located outside and adjacent to Building 90. Conduct soil headspace analyses on each of the soil samples collected from the soil borings utilizing a photo-ionization detector to evaluate relative constituent concentrations between soil intervals and to identify the zone of principal constituent impact at each boring location. Submit the soil sample exhibiting maximum response to soil headspace analyses from each boring for VOC analytical testing using EPA SW-846 Method 8260b.

3.7.2   Collect elevation data of the pavement area surrounding Building 90 to determine surface water flow direction to aid in determining the optimum locations for installing piezometers in support of the groundwater recharge study.

3.8   Future Inputs

3.8.1   Execute a soil gas tracer test.

3.8.2   Execute a groundwater tracer test.

4.0 - Define Study Boundaries (Step 4)

4.1   General Boundary Conditions

4.1.1   Study Boundary The study boundary is limited to the approximate assigned boundaries for AOC-65. The study boundary is sized to facilitate accurate determinations of conditions with bearing on the project scope. The study boundary area will be expanded as necessary to understanding the subsurface geologic structural conditions that impact soil gas migration; determining whether monitored natural attenuation is a viable remedial alternative for groundwater impacted by VOCs at AOC-65; and understanding the relationship between precipitation event frequency, duration, and intensity and vertical infiltration.

The vertical extent of the study area extends through the vadose zone and into the uppermost water-producing zone (Lower Glen Rose Formation) present within the subsurface.

4.1.2   Work Agreement Boundaries

Timely execution of an agreement between the government and the prime contractor is critical toward meeting the September 2003 project completion schedule. Critical tasks such as removal action/restoration rely on timely completion and CSSA approval of the removal action subcontractor bid package, reviewing bids, and selecting subcontractors.

4.1.3   Geophysical Investigation Boundaries

Timely completion and comprehensive evaluation of the various surface geophysical investigations planned for the project is critical in determining the optimum locations of borings performed to validate the geophysical findings. Timely geophysical data interpretation is also critical in determining the optimum location of piezometers installed to coincide with principal fractures identified within the vadose zone.

4.2   Regulatory Compliance Boundaries

4.2.1   Standard exemption notification information should be submitted to TNRCC prior to SVE/subslab vent system operation.

4.2.2   Analytical testing results for investigation derived wastes should be expedited to facilitate timely material disposal methodology decisions to reduce the potential for project schedule delays related to temporary material storage capacity issues.

4.2.3   Analytical testing results for SVE system air emission samples should be expedited to facilitate timely determination of compliance with the TNRCC standard air exemption.

4.2.4   Analytical testing results for the SVE system condensate sample should be expedited to facilitate timely material handling and disposal methodology decisions.

4.3   Groundwater Recharge Boundaries

4.3.1   Information collected within the weather system random access memory must be downloaded at sufficient time intervals to assure no loss of data.

4.3.2   Regular maintenance of the weather station power source must be conducted to assure continuous data collection capability.

4.3.3   Pore pressure transducers must be installed within piezometers and wells at sufficient depths and contain sufficient PSI ratings to allow continuous water level measurement in the event of major water level fluctuation events.

4.3.4   Pore pressure transducer data collection rates, reserve battery capacity, and frequency of data down-loading events must be monitored/scheduled to facilitate continuous water level data recordation.

4.3.5   Scheduling field sampling personnel on-post to coincide with initiation and termination of rainfall events to collect the required pre and post rainfall event groundwater samples from area piezometers is critical to the project.

4.4   SVE Study Boundaries

4.4.1   Base-line analytical results of soil gas samples collected from the VEWs are required to identify the relationship of TVH field screening qualitative data to lab analytical testing results and to select the most appropriate intervals for additional testing and observation.

4.4.2   Soil gas airflow measurement instrumentation should be calibrated each day of use to assure consistent accuracy utilizing the same calibration equipment throughout the entire program.

4.4.3   Instrumentation used to measure TVH, O2, CO2, airflow, and pressure responses should be calibrated each day of use to assure consistent accuracy utilizing the same calibration equipment throughout the entire program.

4.4.4   Scheduling field sampling personnel on-post after 1-hour, 8-hours, 24-hours, 48-hours, 4 days, and possibly 8 days of SVE system operation to collect soil gas samples for appropriate VEWs for EPA method TO-14 VOC analysis.

4.4.5   The program is designed to include provisions to evaluate the relationship between SVE system performance as related to fluctuations in groundwater levels. Therefore, installation of the weather station and piezometers associated with the program must be completed prior to startup of the SVE system treatability study.

4.5   System Layout Boundaries

4.5.1   Information made available through the execution of the surface geophysical investigations and associated soil boring validation program will be used in support for determining the lateral and vertical extent of areas to included within the system layout.

4.5.2   Completion of extraction packer testing within the deepest piezometer installed for the groundwater recharge study is required prior to initiating VEW and VMP well installation activities as the findings of the packer test will support the determination of optimum construction details (location and screened interval) associated with the VEWs and VMPs.

4.6   Removal Action Boundaries

4.6.1   A one-time waiver from TNRCC to the existing Building 90 air permit will be required to be obtained prior to conducting a soil removal action program beneath the Building 90.

4.6.2   CSSA must obtain approval from the State Historical Program Office prior to implementing a soil removal program inside Building 90 that requires temporary alteration of the building dock, walls, windows, or roof.

4.6.3   Validated soil excavation confirmation sample analytical results demonstrating residual constituent concentrations associated with soils forming the base and sidewall of the resulting excavation are required in support of determining soil removal action completion.

4.6.4   Validated Building 90 indoor air quality analytical sample testing results will be required to quantify any potential risks to on-post workers within the building. Analytical samples should be prioritized for quick turn-around to facilitate exposure potential determination.

4.7   Engineering Design Decision Boundaries

4.7.1   Final analytical results for soil samples collected from beneath Building 90 and along drain lines/drainage features outside of Building 90 are required to support the design of the SVE system. This information will be used to determine the locations of maximum soil concentrations in determining optimum locations for VEW placement.

4.7.2   Final disposition or desired drainage area for diverted rainwater from gutters and paved areas will affect the design package and final restoration of the project.

5.0 - Develop a Decision Rule (Step 5)

5.1   Are the screened intervals of the piezometers located in the most effective location (depth interval and lateral spacing)? (Decision 2.1.1, 2.1.2, 2.1.3, 2.1.4, 2.3.1, 2.3.2, 2.3.3, 2.3.4, 2.4.1, 2.5.1, 2.8.1, 2.8.2) If the piezometers are determined to be installed in the most effective location then the program will continue according to plan. If the data generated during the project identifies additional key locations for the installation of piezometers, the prime contractor will discuss the findings with key CSSA personnel. Additional piezometers will be installed at the direction of CSSA.

5.2   Are the locations and screened intervals of the extraction wells and vapor monitoring points installed in the most appropriate locations for determining interconnectivity, radius of influence, and removal capability of the treatability SVE system? (Decision 2.4.2, 2.4.4, 2.4.5, 2.4.6, 2.4.7, 2.5.2, 2.5.3) If the locations and screened intervals of the VEWs and VMPs are determined to be installed in the most effective locations, then the program will continue according to plan. If data generated during the project identifies additional key locations for the installation of VEWs and VMPs to improve the removal of VOCs, the prime contractor will discuss the findings with key CSSA personnel. Additional VEWs and VMPs will be installed at the direction of CSSA.

5.3   Are the emission controls for the SVE treatability and Subslab ventilation system in compliance with applicable requirements and below OSHA exposure criteria? (Decision 2.2.1, 2.2.2, 2.4.6, 2.4.7, 2.4.8, 2.4.9) If the emissions controls for the SVE treatability and Building 90 subslab vent systems are effective at reducing emission concentrations to within acceptable levels, then the project will proceed as planned. If the emissions controls for the SVE treatability and Building 90 subslab vent systems are not effective at reducing emission concentrations to within acceptable levels, then the prime contractor will propose alternative air emission pollution control measures or system design/operation changes to CSSA for consideration. The prime contractor will verify emissions are within acceptable limits after system modifications are implemented.

5.4   Will the subslab ventilation be more effective than excavation to reduce contaminant levels in fill material underlying Building 90? (Decision 2.4.2, 2.4.3, 2.4.6, 2.4.7, 2.6.1, 2.6.3, 2.7.5) If the answer to the question is yes, the Building 90 removal action will be accomplished specifically utilizing the subslab vent system. In the event the subslab vent system is determined ineffective, an active soil removal action will be conducted for soils contained beneath Building 90.

5.5   What mass of contamination can be reasonably contained and pumped from the recharge areas of the vadose zone in groundwater phase in the upper Lower Glen Rose Formation? (Decision 2.1.4, 2.3.2, 2.3.3, 2.3.4, 2.4.1, 2.4.5). If high levels of contaminants are found to linger in groundwater phase at certain portions of the vadose/recharge zone (upper 150 feet), then Parsons will evaluate possible treatment technologies (in situ oxidation, enhanced natural attenuation, and pump and treat) that could be implemented to remediate the groundwater prior to further migration into the drinking water aquifer.

5.6   What are the apparent primary migration routes for contaminants to the groundwater producing formation and where are the largest deposits of contamination located (depth intervals and lateral locations)? (Decision 2.1.1, 2.1.2, 2.1.3, 2.1.4, 2.3.1, 2.3.2, 2.3.3, 2.4.3, 2.5.1, 2.5.2, 2.6.1, 2.6.2, 2.7.4, 2.7.5) If the project data suggests that we have identified the primary contaminant source areas and migration routes, the program will proceed as planned. If data collected suggests we may have not identified the primary contaminant source areas or migration routes or if the installed treatability test system does not adequately treat the contamination deposits, then the prime contractor will evaluate the situation and propose alternate approaches to the program to CSSA for consideration as deemed necessary.

5.7   How does the waste (drill cuttings, excavated material, water from drilling operations, water from SVE systems knock-out pots, etc) generated under this task order need be managed? (Decision 2.2.3.1, 2.2.3.2, 2.2.3.3, 2.2.3.4, 2.2.3.5) Waste materials generated during the program will be managed in accordance with local, state, and federal law. Investigation derived wastes are scheduled to be submitted for total VOC analytical testing using EPA SW-846 Method 8260b.

Analytical results for fluid matrix samples will be compared to concentration limits established for toxicity characteristic hazardous waste. If fluid sample analytical results exceed toxicity characteristic limits, the materials will be transported off-post for disposal as hazardous waste. If fluid sample analytical results are below TNRCC TRRP Tier 1 PCLs for groundwater ingestion, the fluids will be discharged onto the area ground surface. If fluid constituent concentrations are above Tier 1 PCLs for groundwater ingestion, and are below TC hazardous waste classification concentrations, then the fluid will be routed through the on-post granular activated carbon fluid treatment unit prior to discharge onto the post groundsurface.

Analytical results for solid matrix samples will be compared to concentration limits established for toxicity characteristic hazardous waste using the �times twenty� rule. If sample analytical results, when divided by a factor of twenty, exceed toxicity characteristic concentration limits, the materials will be transported off-post for disposal as hazardous waste. If sample analytical results are below TNRCC TRRP Tier 1 PCLs established for residential groundwater protection assuming a 30 acre source area, the materials will be spread onto the area ground surface. If material sample constituent concentrations exceed Tier 1 PCLs for residential groundwater protection, but are below TC hazardous waste classification concentrations, when divided by a factor of twenty, then the material will be transported off-post for disposal as Class II waste.

5.8   What criteria will be employed to demonstrate completion of soil removal actions implemented for the project? (Decision 3.6.1) Excavation activities will continue laterally for areas where soil sample analytical results identify residual soil concentrations exceeding Tier 1 Industrial soil protective concentration limits (PCLs) established for protection of groundwater associated with a Class 1 aquifer assuming a 1/2-acre source area. Vertical excavations will be limited to the top of bedrock, anticipated at 2-4 feet below grade. Once the PCL levels are met as demonstrated within soil confirmation samples, excavation activities will terminate and the resulting excavation backfilled with material that has been certified as acceptable for unrestricted use as general backfill materials.

6.0 - Specify Tolerable Limits for Decision Errors (Step 6)

6.1   Qualitative Data

Several types of data will be collected for the program that is considered screening level data. Decision errors are not assigned to screening level data as this data will not be used to formulate regulatory or closure decisions. The majority of the screening level information will be used to infer the effectiveness of SVE as a remedial alternative. For this reason, typical QA/QC practices to assure extreme accuracy of the data is not required. The types of information to be collected utilizing screening level measurement techniques includes:

6.2   Quantitative Data

Currently, the AFCEE QAPP Version 3.0 is being utilized by CSSA. The QAPP specifies tolerable limits for errors associated with quantitative data collected at CSSA. The quantitative data to be collected in association with the project includes:

7.0 Optimize the Design for Obtaining Data (Step 7)

Refer to Steps 2 and 5 of these DQOs for optimization steps related to the project.