[DQO Table of Contents]

Data Quality Objectives Groundwater Contamination Investigation

April 22, 2002 - Revised xx June 2003
 

1.0 - The Problem (Step 1)

1.1   History/Background

Past operations have contaminated soil, groundwater, and rock at Camp Stanley Storage Activity (CSSA). Previous investigations have documented the presence of volatile organic compounds (VOCs) in all three media and metals and total petroleum hydrocarbons (TPH) in soils. The extents of these contaminants are not fully characterized at CSSA.

CSSA has identified three VOC source areas as sites that have contaminated groundwater. They are Solid Waste Management Units (SWMUs) B-3 and O-1, and Area of Concern (AOC)-65. Based on present knowledge (June 2003), there are two groundwater VOC plumes, known as Plume 1 and 2. Current interpretations suggest Plume 1 is associated with SWMUs B-3 and O-1, and Plume 2’s source is AOC-65. CSSA has identified VOCs at detectable levels in on- and off-post drinking water and monitoring wells. These levels are above and below the maximum contaminant levels (MCLs) for the VOCs of concern. See the attached maps (Figures 1 and 2) that list the ranges of perchloroethene/tetrachloroethene (PCE), trichloroethene (TCE), and cis-1,2-Dichloroethene (DCE) detections as of the June 2003 groundwater monitoring event.

Metals (primarily lead) were identified in soils at various sites due to past operations. Therefore, they have not been included as contaminants of concern (COCs) for off-post groundwater. Metals and TPH require further investigations at selected sites, and if present in soils at excessive levels, may need to be evaluated as a potential threat to groundwater. Ongoing and future CSSA investigations will remediate, excavate and/or remove soils affected with TPH and/or metals in accordance with the appropriate risk reduction regulations.

Polychlorinated biphenyls (PCBs) have been detected; however at concentrations which are below groundwater protective standards. Samples have been collected from CSSA sites (i.e., SWMU I-1) where site usage and/or storage of transformers indicated the possible presence of PCBs.

Six underground storage tank sites were affected by release of petroleum products to the subsurface as determined by previous assessments. In general, releases were confirmed in subsurface soils at each site. Target action levels for soil and groundwater based on site conditions and TCEQ regulations for leaking petroleum storage tanks (LPSTs) were proposed for the sites. Final concurrence was issued for five sites and one site (LPST #101264) is pending final concurrence.

This data quality objective (DQO) document is focused on CSSA’s groundwater monitoring program, well installations, sampling and analyses, recharge studies, and other associated activities.

1.2 - The Planning Team

1.2.1   CSSA

Mr. Brian Murphy, CSP, Environmental Officer, CSSA

Mr. Jeff Aston, Environmental Engineer, US Army Corp of Engineers (USACE)

Mr. Christopher Beal, Contract Geologist, Portage Environmental

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. Julie Burdey, Project Manager

Mr. Brian Vanderglas, Project Manager

Ms. Tammy Chang, Project Chemist

Mr. Gary Cobb, Project Manager

Mr. Scott Pearson, Project Manager

Ms. Kimberly Riley, Task Manager

Mr. Kyle Caskey, Field Team

Ms. Samantha Elliott, Task Manager

1.2.4   The Decision Makers

Mr. Jason D. Shirley, Installation Manager, CSSA

Mr. Brian Murphy, CSSA Environmental Office

Mr. Greg Lyssy, U.S. Environmental Protection Agency (EPA), Region 6

Mr. Sonny Rayos, Texas Commission on Environmental Quality (TCEQ), Corrective Action Section

2.0 - Identify the Decisions - “Prioritized and logical sequence for actions” (Step 2)

2.1   Present Decisions

2.1.1   Determine whether on- and off-post drinking water meets the standards for safe drinking water as prescribed under the EPA and TCEQ rules.

2.1.2   Determine if VOC levels in on-post and off-post drinking water exceed stated values in the CSSA Off-Post Monitoring Response Plan.

2.1.2.1   Is there a detection for any VOC?

2.1.2.2  Does the VOC detection require an action on the part of CSSA or public water system?

2.1.2.3  Reduce the sampling frequency as needed at selected wells based on cumulative analytical results.

2.1.3   Determine which formation(s) in the Middle Trinity Aquifer are impacted by the VOC contaminants.

2.1.4   Determine the efficacy of the Westbayâ sampling device near the southwest corner of the installation.

2.1.5   Determine the impacts of rain events and drought conditions on concentrations and migration of VOCs in the aquifer and vadose zone.

2.1.6   Determine which VOCs should be retained as primary COCs. Modify the VOC analyte list as necessary.

2.1.7   Determine locations of fractures and faults in cooperation with the United States Geological Service (USGS).

2.1.8   Determine whether metals analysis in our on-post monitoring events should be continued or whether the metals testing frequency should be reduced or no longer performed, except per TCEQ rules for drinking water wells.

2.1.9   Identify data gaps in groundwater monitoring program, including, but not limited to plume delineation, analyte lists, additional well locations, fracture flow/matrix flow/conduit flow determinations, water balance issues (precipitation data, published recharge infiltration rates, discharge from water supply wells and other parameters), and recharge study concepts.

2.2 Remediation Decisions

2.2.1 Determine potential remediation goals based upon the media impacted and COCs. Identify cost-effective and technically appropriate, remedial alternatives (i.e. soil vapor extraction, monitored natural attenuation, pump and treat, chemical treatment, etc.) for cleaning up groundwater.

2.2.2 Continue to determine the effectiveness of the granular activated carbon (GAC) filtration units for the removal of VOCs from public and private off-post wells. Determine if additional GAC units are needed as specified in CSSA’s Off-post Monitoring Response Plan.

2.2.3 Determine if the plume is expanding or shrinking for future remediation decisions involving monitored natural attenuation, etc.

2.3 Future Decisions

2.3.1 Determine if additional off-post drinking water wells need to be sampled, and if so, identify the most appropriate locations to monitor the status of the plumes.

2.3.2 Select proper placement of future monitoring wells on- and off-post from geophysical surveys and sampling data.

2.3.3 Determine whether groundwater sampling should be expanded or reduced for on- and off-post wells based on recent and historical data.

2.3.4 Determine when modifications to the CSSA Off-post Monitoring Response Plan are necessary and provide to the EPA and TCEQ.

2.4 Alternative Decision

2.4.1 No action (No additional groundwater monitoring or program activities).
 

3.0 Identify Inputs (Step 3)

3.1 General Inputs

3.1.1 TCEQ collects VOC samples from public drinking water wells every three years per the State rules. At their discretion, they also collect split samples from off-post well locations.

3.1.2 Upon completion of a new monitoring well, metals analyses, (arsenic, barium, cadmium, chromium, copper, lead, mercury, nickel, and zinc) consistent with previous on-post sampling events, will be performed. Detection of metals in groundwater samples has generally been limited to agricultural wells in the north pasture. Infrequently, samples from drinking water wells have had detections of metals too. Upon completion of the historical metals results tables, examine whether to reduce the metals analyte list. (Parsons must prepare analytical summary table)

3.1.3 Currently, the first time a newly installed monitoring well is sampled, a full suite of VOCs will be analyzed. At the present time, the sampling frequency has been determined to be quarterly for VOC and other COCs that may have been detected in the initial event.

3.1.4 Based on historical data, ongoing findings, and the recharge study being conducted at Building 90/AOC-65, any proposed modifications for future sampling (both frequency and analyte lists) will be forwarded to EPA and TCEQ for concurrence.

3.1.5 Data collection and sampling activities will be based on trend data from monthly, quarterly, or any other monitoring event.

3.1.6 Collect and analyze data to determine where fractures and faults are located.

3.2 Off-post Inputs

3.2.1 Currently all off-post drinking water wells require analysis for the March 2003 approved short list of VOCs upon initial sampling. The CSSA VOCs “short list” consists of bromodichloromethane, bromoform, chloroform, dichlorodifluoromethane, dibromochloromethane, 1,1-dichloroethene, cis-1,2-dichloroethene, trans-1,2-dichloroethene, methylene chloride, naphthalene, tetrachloroethene, trichloroethene, toluene, and vinyl chloride.

3.2.2 Collect and analyze pre- and post-GAC water samples for VOC COCs (the short list per 3.2.1 above) to determine if the GAC system is working effectively, or if any other action is required. Pre-GAC samples will be collected quarterly. Post-GAC samples will be collected bi-annually.

3.2.3 Private wells OFR-3, LS-6, LS-7, RFR-10, and RFR-11, and future wells that have a GAC system installed require semi-annual GAC maintenance, which occurs every February and August. Post-GAC samples will be collected to confirm each system’s effectiveness during the next scheduled quarterly sampling event after maintenance has occurred.

3.2.4 Public wells LS-2 and LS-3 require GAC maintenance be performed every 470 days (18 months). Post-GAC samples will be collected to confirm system effectiveness. At a minimum, post-GAC confirmation samples will be collected every six months and during the quarterly sampling event after maintenance occurs.

3.2.5 If a new public or private well is found with elevated VOC levels (≥ 90% of MCL) GAC treatment will be installed or plans to connect the well to another drinking water source will be initiated. A post-GAC confirmation sample will be collected (usually within 72 hours) after installation.

3.2.6 Action levels for detection of VOCs and decisions to sample an off-post private well are based on the following, see also Figure 3.

3.2.6.1 If VOC contaminant levels are ≥ 90% of the MCL based on preliminary data received from the laboratory (≥ 4.5 parts per billion (ppb) for PCE and TCE) and the well is used as a potable water source, bottled water will be supplied within 24 hours of receipt of the data, and a confirmation sample will be collected from the well. The re-sampling will take place within 14 days of the receipt of the final validated analytical report. If the follow-up sampling confirms a COC is above MCLs, the residence or supply well will be evaluated and an appropriate method for wellhead protection, either installation of GAC or connection to an alternative water source will be selected. Cost related to the installation and maintenance of wellhead treatment equipment or connection to an alternative water source will be borne by CSSA.

3.2.6.2 If VOC contaminant levels are ≥ 80% of the MCL during any single monitoring event based on preliminary data from the laboratory (4.0 ppb for PCE and TCE) and the well is used as a potable water source, it shall be monitored monthly. If the follow-up sampling confirms a COC is ≥ 80% of the MCL, it will be re-sampled until the level falls below the 80% value. If the concentration increases to ≥ 90% of the MCL see 3.2.6.1 above.

3.2.6.3 If any VOC COC is detected at levels ≥ the MDL (historically around 0.11 ppb for PCE and 0.14 ppb for TCE), and less than 80% of the MCL the well will be re-sampled on a quarterly basis. This sampling will be conducted concurrently with on-post sampling events and will be used to develop historical trends in the area. Quarterly sampling will continue for a minimum of one year, after which the sampling frequency will be reviewed and possibly decreased.

3.2.6.4 If VOCs are not detected during the initial sampling event, (i.e. no VOC contaminant levels above the MDL), further sampling of the well would be considered on an as needed basis. A well that has no detectable VOCs can be removed from the sampling list, unless plume migration could influence the well. The well owner will be apprised of any re-sampling decisions regarding the non-detect wells.

3.2.7 Action levels for detection of VOCs and decisions to sample an off-post public well are based on the following, see also Figure 3.

3.2.7.1 If an off-post public supply system is ≥ 90% of the MCL, CSSA will coordinate solutions to the maximum extent practicable. The system operator and CSSA will determine the best course of action for providing potable water when data suggests an exceedance of the MCL. Possible options include:

3.3 On-post Inputs

3.3.1 Prior to October 1999 and during the periodic TCEQ sampling events, all on-post wells have been tested for the complete list of VOC analytes. Since 1999, these wells were tested using the October 1999 short list for VOCs. The short list included bromodichloromethane, chloroform, dibromochloro-methane, 1,1-dichloroethene, cis-1,2-dichloroethene, trans-1,2-dichloro-ethene, methylene chloride, tetrachloroethene, trichloroethene, and vinyl chloride. Beginning with the March 2003 quarterly sampling event, the on-post “short list” has been modified to include bromoform, dichlorodifluoromethane, naphthalene, and toluene. The short list was modified so the on-post VOC short list is the same as the off-post VOC short list.

3.3.2 Compliance sampling for metals required under the Safe Drinking Water Act for CSSA’s drinking water wells (CS-1, CS-9, and CS-10) will be continued per TCEQ rules.

3.4 Drinking Water Well Sampling Scheme

3.4.1 Public and private off-post drinking water wells have had VOC detections. Additional information is available in Volume 5, Groundwater of the CSSA Environmental Encyclopedia. All future samples from off-post wells will be analyzed for VOCs utilizing the short list which is identified in 3.3.1 above.

3.4.2 CSSA drinking water wells have had VOC detections and will be sampled quarterly per the Off-Post Monitoring Response Plan: CS-1, CS-9, and CS‑10. All future repeat samples from off-post wells will be analyzed for VOCs utilizing the short list which is identified in 3.3.1 above.

3.4.3 Expansion or reduction of the off-post wells to be sampled will be dependent on an evaluation of historical results. New off-post drinking water wells may be added to the program in the future. Locations of new wells to be sampled will be based on the inferred-flow direction of the off-post VOC plume derived from historical data. Concerns of area residential well owners or municipal water purveyors will be dealt with on a case-by-case basis. These decisions will be made based on the action levels given in 3.2.6 above. Additional information on the addition of off-post wells to the sampling program is available in Volume 5, Groundwater, of the CSSA Environmental Encyclopedia.

3.5 Existing On-post Monitoring and Agricultural Wells

3.5.1 Existing on-post monitoring wells will be sampled on a quarterly schedule. As of June 2003, there are 41 existing monitoring wells: (see attached map Figure 4). Existing wells are: CS-MW1-LGR, CS-MW1-BS, CS-MW1-CC, CS-MW2-LGR, CS-MW2-CC, CS-MW3-LGR, CS-MW4-LGR, CS‑MW5‑LGR, CS-MW6-LGR, CS-MW6-BS, CS-MW6-CC, CS‑MW7‑LGR, CS-MW7-CC, CS-MW8-LGR, CS-MW8-CC, CS‑MW9‑LGR, CS-MW9-BS, CS-MW9-CC, CS-MW10-LGR, CS‑MW10‑CC, CS-MW11A-LGR, CS-MW-11B-LGR, CS-MW12-LGR, CS-MW12-BS, CS-MW12-CC, CS-MW16-LGR, CS-MW16-CC, CS‑MW17-LGR, CS-MW18-LGR, CS-MW19-LGR, CS-2, CS-3, CS-4, CS-D, CS‑MWG-LGR, CS-MWH-LGR, CS-I, CS-WB1-LGR, CS-WB2-LGR, CS-WB3-LGR, and CS-WB4-LGR. There are also five monitoring wells located at Building 90: AOC-65-MW1, AOC‑65‑MW2A, AOC-65-MW2B, AOC-65-MW3, and AOC-65-MW4. Other wells will be added to the quarterly events as they are completed.

3.5.1.1 A newly installed monitoring well will be sampled for the full list of VOCs (8260B), metals, and selected groundwater quality parameters. Subsequent monitoring events will utilize the approved March 2003 short list, if no other VOCs are detected and no metals are detected above action levels.

3.5.1.2 The six existing agricultural and open-borehole wells: CS-2, CS-3, CS-4, CS-11, CS-D, and CS-I will be sampled utilizing the March 2003 VOC short list. These wells will be monitored quarterly, on an as needed basis based on detections. (Should an existing well be upgraded, the full list of VOCs and the nine CSSA metals will be analyzed during the initial event following its upgrade.)

3.5.2 An evaluation of cumulative detections was performed for on-post monitoring, drinking water, and agricultural wells that have been sampled since 1995. Based on these historical detections, the VOC short list was modified and approved by the regulators. The decision to continue monitoring for the presence of contaminants (VOCs) or exclusion of a particular well or wells from quarterly monitoring will be based on continuing trend analysis from cumulative analytical results. Other factors contributing to removal or inclusion of a well from the monitoring schedule include: proximity of the sampled well to public/private production wells, construction details of the well, location of the well(s) relative to other nearby wells, and value of the well to the overall evaluation program.

3.5.3 Water Levels

Water levels will be collected from all available wells at least quarterly. Additional water level data will be collected weekly, monthly and/or after significant rainfall events are measured. Water level gradient/potentiometric maps will be prepared separately for each formation of the Middle Trinity Aquifer. As investigations progress, impacts from open boreholes and faults to the CSSA groundwater gradient should become more evident.

3.6 New Monitoring Wells

3.6.1 CSSA will complete the installation of new monitoring wells at locations to be determined in the future.

3.6.2 Wells will be installed as individual wells or in two or three well clusters. A cluster includes two or three wells located within proximity to each other (~30 feet) and completed in the different formations being studied (i.e. Lower Glen Rose, Bexar Shale and Cow Creek). This will allow evaluation of the potential vertical migration if VOC contaminants in each cluster location and provide data for determining possible impacts to each aquifer formation being sampled.

3.6.3 Past soil and rock sampling at monitoring well installation sites for VOCs have yielded scattered detections of laboratory contaminants and non-detect for VOC and COCs. Therefore, as a general rule, soil/rock samples will not be collected for testing during subsequent well installations at CSSA. However, if a PID reading, discoloration, or an odor indicates potential contamination, the supervising geologist may opt to collect a sample for testing of COCs to determine the type(s) of contaminants present and whether concentrations are indicative of free-phase deposits.

3.6.4 Injection testing will not be performed in any new well installations. Past data collected has been qualitative, but are not definitive.

3.6.5 Coring at each well site has provided a wealth of information and helped correlate data from electrical geophysical logging. Detailed logging of well cores will be continued in at least one well per cluster or the use of another appropriate geophysical method will be

3.6.6 Downhole camera surveys will be conducted at some of the well sites. At a minimum, camera surveys will be performed at the locations where Westbay® devices are to be installed to help identify appropriate intervals for placement of the multi-level sampling devices.

3.6.7 Past experience at CSSA has shown that borehole geophysical logging is a valuable tool for confirming subtle lithologic changes, comparison of cross-borehole characteristics (stratigraphy), and even inferring fault planes. Resistivity, spontaneous potential (SP), gamma ray, and caliper logging shall be collected from each new borehole. This data will complement the borehole coring and will be evaluated to compare apparent similarities and differences of stratigraphy and geophysical properties between well locations and depth profiles.

3.6.8 Based on previous sampling results, most wells installed should require single cased completions only. However, to avoid cross contamination, new wells in area of known VOC contamination may be installed with multiple casing strings. Additional changes to this casing strategy will be evaluated if analytical results from discrete interval testing indicate elevated levels of contamination. As a contingency, an adequate volume of eight inch casing will be on-post during drilling to allow installation of surface casing as needed. Temporary casing installed with bentonite sealer is another option to be considered if significant up-hole contamination is identified.

3.6.9 Data-loggers and transducers have been installed at on-post monitoring wells. Additional transducers may be installed in future wells. Each data-logger is SCADA compatible and continuously collects and stores information regarding static water level, water temperature, and/or conductivity. Telemetry may be employed at key wells to provide up-to-date data on demand once a telemetry system is identified and funding is available.

3.6.10 Upon completion of well development, dedicated low-flow pumps will be purchased and installed in each new monitoring well. The pumps will be pneumatically operated bladder pumps consistent with the monitoring system already existing at CSSA.

3.6.11 Water levels, construction, and survey data for wells needs to be collected for the CSM, for incorporation into the groundwater model and any future risk assessments. Specific study area boundaries (a watershed boundary for example) will be established relative to the CSSA property, offsite boundary conditions (pumping wells), areas of recharge/discharge (creeks and springs), and major fault and fracture systems. The CSM will be developed to assist in describing groundwater flow patterns and contaminant migration.

3.6.12 Obtain pressure data to calculate groundwater gradients in the vertical and horizontal. Collect multilevel samples from the device to analyze for VOCs. Collect hydrogeologic data to determine “K” using slug tests, pumping tests, and sample container fill rates.

3.6.13 In general, CSSA will be responsible for collection of data from the Westbay® wells. Parsons will supply one field technician per groundwater sampling event. Groundwater samples will be collected from discrete intervals using the Westbayâ device for a period of 12 months. Sampling frequency will utilize the following parameters:

3.6.13.1 Every month (30 days) as a standard, and

3.6.13.2 Possibly every 15 days depending on water elevations and changes in groundwater quality parameters.

Note: Samples may be collected within 72 hours of significant rain events. This allows for samples to be collected on Monday should the rain event occur on Friday. After each sampling event the data will be evaluated to determine if monthly or other sampling is necessary.

3.6.14 Pressure readings will be recorded at selected depth intervals in the Westbay® wells prior to sampling any activities, or at least twice per month (every 15 days).

3.6.15 Data gaps will be identified in the CSM and all future updates to that document.