September 2003 On-Post Quarterly Groundwater Report

Groundwater monitoring scoped under the Air Force Center for Environmental Excellence (AFCEE) 4P/AE Contract 41624-03-D-8613, Task Order (TO) 0008, was performed the week of September 15, 2003, at Camp Stanley Storage Activity (CSSA). On-post groundwater monitoring conducted under this TO began with the September 2003 sampling event and will be completed with the March 2004 sampling event. Groundwater monitoring conducted prior to September 2003 was conducted under various delivery orders as shown in Table 1 of the Introduction to the Groundwater Monitoring Program, Volume 5. AFCEE/Environmental Restoration Directorate (ERD) and AFCEE/Environmental Restoration Consultant (ERC) provide technical oversight of the monitoring program.

The current objectives of the groundwater-monitoring program are to determine groundwater flow direction and elevations, determine groundwater contaminant concentrations for characterization purposes, and identify meteorological and seasonal variations in physical and chemical properties. Appendix A identifies the data quality objectives (DQOs) for CSSA�s groundwater monitoring program, along with an evaluation of whether each DQO has been attained. The objectives listed in the table also reference appropriate sections of the 3008(h) Administrative Order on Consent (Order). Overall DQOs for the investigations at CSSA are provided in Volume 1-1 behind the RFI Addendum tab (Section 11).

Thirty-nine water level measurements were recorded on September 25, 2003. Water level measurements were collected from CSSA wells CS-1, CS-2, CS‑3, CS-4, CS‑10, CS-11, CS‑MW16-LGR, CS-MW16-CC, CS-D, CS-MWG-LGR, CS-MWH-LGR, CS-I, 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-MW10-LGR, CS‑MW10-CC, CS-MW11A-LGR, CS-MW11B-LGR, CS-MW12-LGR, CS-MW12-BS, CS‑MW12-CC, CS-MW17-LGR, CS-MW18-LGR, and CS‑MW19-LGR. A water level was not collect from CS-9 due to a downhole obstruction. All water levels were measured with an e-line water level indicator. Transducer data was also collected from wells CS-1, CS-10, CS-11, CS‑MW1-CC, CS-MW2-CC, CS-MW4-LGR, CS-MW9-LGR, CS‑MW9-BS, CS-MW11A-LGR, CS-MW11B-LGR, CS-MW12-CC, CS-MW16-LGR, CS-MW16-CC, and CS-MW19-LGR. The transducer in well CS-MW9-CC has been temporarily removed due to malfunction. Transducer data is discussed in Section 3.0. An average groundwater elevation for off-post well FO-20 during the week of September 25, 2003, was obtained from Fair Oaks Water Utilities.

On average, groundwater elevation levels for wells screened in the Lower Glen Rose decreased 54.93 feet between June 16, 2003 and September 25, 2003. Depth to groundwater subtracted from top of casing elevations and the water level elevations are summarized in Table 1-1. Table 1-2 summarizes the changes in groundwater elevations compared to the June 2003 event. The current groundwater elevations may be compared to the historical groundwater elevations from October 1992 through the most recent groundwater monitoring event in Table 3 of the Introduction to the Quarterly Groundwater Monitoring Program (Parsons, 2002) (Volume 5, Groundwater).

An average groundwater elevation for the Lower Glen Rose Limestone (LGR), Bexar Shale (BS), and Cow Creek Limestone (CC) is provided in Table 1-1. The averages were calculated using the groundwater elevations from wells screened in only one formation. Water elevations from wells completed with open boreholes over multiple formations were not used. Typically, the water levels measured at CSSA decrease from the LGR to the BS to the CC. In September 2003, the average groundwater elevation did not follow this typical pattern. The average groundwater elevations in September 2003 for the LGR, BS, and CC were 1046.77 feet, 1060.39 feet, and 1025.61 feet, respectively. This was a decrease of 54.93 feet in the LGR, 19.35 feet in the BS, and 62.68 feet in the CC from the average levels measured in June 2003. Evaluation of trends in water level elevations in the different formations will continue as additional wells are completed.

A groundwater potentiometric surface map generated from the September 2003 groundwater elevations is shown in Figure 2-1. Among the cluster wells CS‑MW6‑LGR, CS-MW7-LGR, CS-MW8-LGR, CS-MW9-LGR, CS-MW10-LGR, and CS-MW12-LGR, only the water level measurements from the LGR were used in creating the potentiometric surface map. The September 2003 potentiometric surface map indicates varying flow directions. The overall calculated groundwater gradient is south-southwest at 0.0045 feet/feet. Groundwater flow directions and gradients during past monitoring events are provided in Section 3.0 for comparison.

The September 2003 potentiometric surface map for LGR-screened wells (Figure 2‑1) exhibited a wide range of groundwater elevations, from a minimum of 1024.96 feet above mean sea level (MSL) at CS‑MW10‑LGR to a maximum of 1118.14 feet MSL at CS-MWG-LGR. The groundwater elevations are generally higher in the northern and central portions of CSSA. The groundwater elevations become lower to the southwest and southeast with well CS-MW10-LGR having the lowest groundwater elevation of all LGR screened wells. In September 2003, well CS-I also had one of the lowest water levels measured. CS-I is not completed with screen in the LGR, but is an open borehole well located in the northern portion of CSSA.

There are exceptions across CSSA to the general south-southwest direction of flow for groundwater. Well CS-MW4-LGR in the central portion of CSSA has the second-highest groundwater elevation (1082.35 ft MSL) of LGR screened wells measured in September 2003 (Figure 2-1). This groundwater elevation is 27.52 feet MSL higher than the nearest comparable well (CS-MW2-LGR) to the north. The CS-MW4-LGR well consistently reports a higher groundwater elevation than other nearby wells screened in the same formation. Unlike the general trend at CSSA, groundwater flow is to the northwest immediately surrounding CS‑MW4‑LGR.

The groundwater gradient/potentiometric surface map presented in Figure 2-1 incorporates measured groundwater elevations from the LGR screened wells only. In the area near Building 90, in the southwest corner of CSSA, two potentiometric surface maps were created using September 2003 groundwater elevations from wells screened in the LGR and CC (Figure 2-2 and Figure 2-3, respectively). The LGR potentiometric surface map for September 2003 indicates a groundwater flow direction to the south near Building 90. This direction is consistent with the December 2002, March 2003 and June 2003 groundwater elevations. The CC potentiometric surface map indicates that September 2003 groundwater flow is to the north. The flow direction within the CC reverses direction dependent upon precipitation events. The September and December 2001 events showed a groundwater flow to the north in the CC, which reversed to a flow direction to the south for March 2002 and June 2002. The flow direction reversed to the north in September 2002 and changed to the south in December 2002 and March 2003. The flow direction in the CC has again reversed to flow to the north in June 2003 and September 2003. Analysis of precipitation data shows that the groundwater flow direction near Building 90 in the CC may reverse flow direction to the north in response to increased precipitation events.

From June 2002 through September 2003, groundwater level measurements were recorded to track the impact of rainfall events occurring at CSSA. Groundwater elevations at the well clusters located at CS-MW6, CS-MW7, CS-MW8, and CS-MW10 were closely monitored. Figure 2‑4 presents groundwater elevations from each well cluster compared to daily precipitation values from the northern CSSA weather station adjacent to well CS-MW16-LGR. Between June 27, 2002 and July 4, 2002, CSSA received 20.67 cumulative inches of rain. This figure illustrates the changes in groundwater elevations over time and illustrates groundwater recharge to the different formations at each well cluster.

As shown in Figure 2-1, water levels at CSSA vary greatly. This variability is associated with several factors:

Until June 2001, when cluster wells were first installed and monitored at CSSA, most potentiometric surface maps were based on water levels from wells with different completion depths. Additional information concerning this issue is included in the Introduction to the Quarterly Groundwater Monitoring Program (Volume 5, Groundwater). Interpretation of past data for the overall potentiometric surface map is complicated by these well completion depths differences. Wells completed in the LGR only are used for Figure 2-1. As more wells are completed in the different formations, use of data from wells screened through the CC and BS can also be evaluated.

Fourteen wells, CS-1, CS-10, CS-11, CS-MW1-CC, CS-MW2-CC, CS-MW4-LGR, CS‑MW9-LGR, CS-MW9-BS, CS-MW11A-LGR, CS-MW11B-LGR, CS-MW12-CC, CS‑MW16-LGR, CS-MW16-CC and CS-MW19-LGR are equipped with transducers to continuously log groundwater levels. Two weather stations, one adjacent to well CS‑MW16‑LGR and one in the southeast corner of CSSA adjacent to AOC-65, record weather data including precipitation and other weather characteristics. The data is evaluated together to identify trends in groundwater recharge. Precipitation data collected from the weather station at well CS-MW16-LGR between October 5, 1998, and September 18, 2003, are shown in Figure 3‑1, along with groundwater elevation data from the transducer. Well CS-MW16-LGR was originally completed as an open borehole through the LGR, BS, and CC Formations. In July 2002, this well was re-completed with a 25-foot screen interval within the Lower Glen Rose. Figure 3-1 illustrates rapid rises in groundwater elevation within well CS-MW16-LGR immediately following a rain event. Additional discussion of trends in groundwater recharge and comparisons between formations will be included in the Annual Groundwater Monitoring Report. CS-MW16-LGR groundwater elevation data from the June 2001 event through the September 2001 monitoring event is missing from Figure 3-1 due to a technical malfunction of the transducer. On May 21, 2002, the transducer was removed from CS-MW16-LGR for telemetry testing and the transducer was returned to the well on June 6, 2002. Transducer data is also missing from June 20, 2002 through July 10, 2002, due to the well construction upgrade of CS-16 to CS-MW16-LGR.

Overall, groundwater levels decreased an average of 52.85 feet between June 16, 2003 and September 25, 2003. During this period, there were 30 rainfall events with a total precipitation of 8.05 inches. During the previous quarter when groundwater levels decreased 41.08 feet, there were 17 rainfall events with a total precipitation of 4.67 inches. For comparison of all events, Table 3-1 demonstrates the total precipitation received each quarter, average groundwater elevations in each formation, and the average groundwater elevation change, whether increase or decrease.

In Figure 3-2, the groundwater elevation data for the CS-MW9 cluster wells was plotted in comparison to the daily precipitation as measured from the meteorological station at CS‑MW16‑LGR. Well CS‑MW9-CC groundwater elevation data from December 2002 to September 2003 does not appear in Figure 3-2 due to battery failure in the transducer. This transducer will not be repaired at this time. The purchase of SCADA compatible transducers is currently being negotiated and a replacement transducer will be installed in the future. Transducer data collected from wells CS-MW16-LGR and CS-MW4-LGR is shown in Figure 3‑3. Results for well CS‑MW4‑LGR are missing from March 23, 2002 to September 3, 2002 due to a technical malfunction of the transducer and those values have been interpolated into the chart.

Four multi-port Westbay^�-equipped wells were installed and will be sampled on a monthly basis for a minimum of one year. These wells are CS-WB01-LGR, CS-WB02-LGR, CS‑WB03‑LGR, and CS-WB04-LGR (see Figure 2-1). In general, CSSA will be responsible for collection of data from the Westbay^� wells. Parsons will supply one field technician per groundwater sampling event.

Optical televiewer and hydrophysical data were collected by borehole geophysics and utilized for monitoring zone selections. All collected data was reviewed to determine the number and location of monitoring zones. Forty-seven zones were selected as monitoring horizons: ten zones each in CS-WB01-LGR, CS-WB02-LGR, CS-WB03-LGR, and 17 zones in CS‑WB04‑LGR. One-third of the zones are expected to be non-yielding during most of the year. It is anticipated that the upper zones will only produce water during periods of significant precipitation.

At each sampling event, the field sampling team will obtain pressure data from each zone with groundwater in order to calculate gradients both vertically and horizontally. A complete profile will be collected along with each sampling event. CSSA and Parsons will select zones for sampling and decide whether purging is warranted for each event. The purge water will be containerized and transported for treatment by the granular activated carbon (GAC) treatment system prior to discharge at CSSA�s Outfall 002. Groundwater samples will be collected from discrete intervals using the Westbay^� device for a period of 12 months. The wells will be sampled for a specific short list of VOCs: tetrachloroethene (PCE), trichloroethene (TCE), cis‑1,2-dichloroethene (cis-1,2-DCE), trans-1,2-dichloroethene (trans-1,2-DCE), acetone, toluene, and 2-butanone.

The sampling frequency will be once each month (30 days) as a standard, with the option of sampling every 15 days depending on groundwater elevations and changes in groundwater quality parameters. 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 monitoring or other frequency is necessary. Pressure readings will be recorded at selected depth intervals in the Westbay^� wells prior to sampling activities, or at least twice per month (every 15 days).

Sampling of the wells is based upon the AFCEE Handbook procedures with exceptions as appropriate for the hydrogeology at the site. The wells were purged as necessary using a water pump. The field sampling team has been following the methods approved in the project�s QAPP and the SAP. QA/QC sampling and analysis was performed to meet the requirements in the CSSA QAPP and project DQOs.

In September 2003, 35 samples were collected from the 47 zones to begin establishing vertical profile and contaminant trends. Eleven of the monitoring zones were dry and could not be sampled. Samples were shipped to DHL Analytical (DHL) for analyses. Nine zones were sampled from CS-WB01 on September 10, 2003, eight zones from CS-WB02 on September 9, 2003, seven zones from CS-WB03 on September 10, 2003, and twelve zones from CS-WB04 on September 19, 2003. Dry zones that were unable to be sampled were WB01‑UGR‑01 (34-46'), WB02-UGR-01 (34-46'), WB02-LGR-02 (81-105'), WB03‑UGR‑01 (20-37'), WB03-LGR-01 (42-68'), WB03-LGR-02 (73-100'), WB04-UGR-01 (23-52'), WB04‑LGR-01 (57-84'), WB04-LGR-02 (89-110'), and WB04-LGR-03 (115-135'). Table 4-1 summarizes the results for the zones sampled during September 2003 and combined results for the COC concentrations in the different zones from the four wells.

Graphical representations of PCE and TCE concentrations from sampled monitoring zones in the Westbay^� wells are presented in Figures 4-1 and 4-2. The depths indicated for each monitoring zones range from the minimum depth to the maximum depth of each zone throughout all four Westbay^�wells. Detections of PCE and TCE occurred in all four Westbay^� wells and cis-1,2-DCE was detected in four zones within WB04. PCE results ranged from a maximum of 148 μg/L in WB03-LGR-09 (297-312�) to a minimum detected concentration of 2.04 μg/L. The only Westbay^� zones sampled which were non-detect for PCE were WB04 zones LGR-04 (140‑199�), BS-02 (412-434�), CC-01 (439-469�), and CC-03 (495-513�). TCE results ranged from a maximum concentration of 10.70 μg/L in WB01-LGR-03 (123-138�) to a minimum detected concentration of 1.01 μg/L. All Westbay^� monitoring zones reported detections of TCE, though the results for WB04, zones LGR-06, BS-2, CC-01, CC-02, and CC‑03 were flagged with a J flag. Cis-1,2-DCE was detected in WB04 only, in monitoring zones LGR-06 (204-231�), LGR-07 (236-261�), LGR-08 (266-302�), and LGR-09 (307-320�), at concentrations ranging from 1.62 μg/L to 2.02 μg/L. Acetone was detected in WB02, WB03 and WB04, at concentrations ranging from 5.1 μg/L to 11.00 μg/L, though all results were J flagged. After further investigation the acetone results were theorized to be the result of equipment decontamination procedures. Future sampling events will include submission of equipment blanks to determine whether acetone detections are due to equipment rinse procedures. Toluene, trans-1,2-DCE, and 2-Butanone were not detected from all monitoring zones sampled of the Westbay^� wells. Depth profiles of pressure data for each of the four wells measured during the September sampling event are presented in Figure 4-3.

On-post groundwater sampling was performed September 15-25, 2003. Thirty-two on-post wells were sampled using dedicated low-flow pumps: CS-2, CS-D, CS‑MWG-LGR, 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-MW11B-LGR, CS-MW12-LGR, CS‑MW12-BS, CS-MW12-CC, CS-MW16-LGR, CS-MW17-LGR, CS-MW18-LGR, and CS‑MW19-LGR. Six wells, CS-1, CS-9, CS-10, CS-11, CS-MWH-LGR and CS-MW16-CC were sampled using high capacity submersible pumps. One additional sample (CS-4) was collected from a monitoring well near well CS-2. One sample was collected from the windmill (CS-I) which has recently been equipped with a solar-driven submersible pump.

The analytical program for on-post monitoring wells includes short-list volatile organic compound (VOC) analysis. Samples from the drinking water supply wells (CS‑1, CS-9, and CS-10) and one newly installed well (CS-MW16-CC) were analyzed for the full list of VOCs, as well as nine metals. Anions and cations were also analyzed for newly installed well CS‑MW16‑CC. On-post monitoring wells are analyzed for metals once annually. The June 2004 event is the next scheduled annual sampling for metals, including arsenic, cadmium, lead, barium, chromium, copper, nickel, zinc, and mercury. These nine metals were chosen based on CSSA�s known waste disposal records and process knowledge. The on-post monitoring wells were analyzed for the short-list of VOC analytes including bromodichloromethane, bromoform, chloroform, dibromochloromethane, dichlorodifluoromethane, 1,1-dichloroethene (DCE), cis-1,2-DCE, trans-1,2-DCE, methylene chloride, naphthalene, tetrachloroethene (PCE), trichloroethene (TCE), toluene, and vinyl chloride.

The Parsons data package ID numbers TO 0008-#3 through #7 contain the analytical results for this sampling event. The data packages were received by Parsons from October 17 to October 28, 2003 and subsequently validated and submitted to AFCEE on November 4, 2003. AFCEE approval of the packages was received December 1, 2003. All detected concentrations of VOCs are presented in Table 5-1. Full analytical results are presented in Appendix B. Cumulative VOC and metals data from this round and all previous sampling events can be found in Tables 6 and 7, respectively, of the Introduction to the Quarterly Groundwater Monitoring Program (Parsons, 2001) (Volume 5, Groundwater).

Activity	Objectives	Action	Objective Attained?	Recommendations
Field Sampling	Conduct field sampling in accordance with procedures defined in the project work plan, SAP, QAPP, and HSP.	All sampling was conducted in accordance with the procedures described in the project plans.	Yes.	NA
Characterization of Environmental Setting (Hydrogeology)	Prepare water-level contour and/or potentiometric maps (B.3.A.1(e)(1))	Potentiometric surface map was prepared based on water levels measured in each of CSSA�s wells on September 25, 2003. In addition, an average water level for a Fair Oaks Ranch Utilities well (F0-20, northwest of CSSA) was also obtained.	To the extent possible with data available. Due to the limited data available and the fact that wells are completed across multiple water-bearing units, potentiometric maps should only be used for regional water flow direction, not local. Furthermore, pumping in the area likely affects the natural groundwater flow direction.	As formation-specific water level information becomes available, prepare water level map for each unit. At present, water levels in all CSSA wells should continue to be measured and all data should be mapped together due to the lack of data for any one zone. Comparisons between LGR and CC screened water levels in the vicinity of Building 90 are being performed currently. As additional wells are installed screened in distinct formations, future evaluations will eliminate reliance on wells screened across multiple formations.
	Describe the flow system, including the vertical and horizontal components of flow (B.3.A.1(e)(3)).	Potentiometric maps were created using September 25, 2003 water level data, and horizontal flow direction was tentatively identified. Insufficient data are currently available to determine vertical component of flow.	As described above, due to the lack of aquifer-specific water level information, potentiometric surface maps should only be used as an estimate of regional flow direction.	Same as above.
	Identify any temporal changes in hydraulic gradients due to seasonal influences (B.3.A.1(e)(4)).	Downloaded data from continuous-reading transducer at CS-MW16-LGR, CS-MW4-LGR, CS-MW9-LGR, CS-MW9-BS, and continuous-reading weather stations adjacent to CS-MW16-LGR and AOC-65. Graphed water levels at these wells against precipitation.	Information provided by CS-MW16-LGR transducer-weather station is a start to identifying temporal changes. Very rapid changes in water levels have been observed at CS-MW16-LGR after precipitation. However, CS-MW16-LGR has just been upgraded to provide data for the Lower Glen Rose water bearing zone.	Install transducers in several cluster wells, after installation is complete, to determine effects of precipitation on each unit. Wells where rapid effects are noticed, such as at wells CS-D and CS-MW1-LGR (both completed in the Glen Rose only), should also be considered for transducer installation.
Contamination Characterization (Ground Water Contamination)	Characterize the horizontal and vertical extent of any immiscible or dissolved plume(s) originating from the Facility ((B.3.C.1(a))	Samples for laboratory analysis were collected from 40 of 41 CSSA wells. Well CS-3 was not sampled because it is located adjacent to well CS-2 and CS-4, which were sampled.	There are currently insufficient data to determine the horizontal or vertical extent of groundwater contamination.	As described above, additional wells are currently being installed which will help in determining horizontal and vertical extent of contamination. Repairs are to be completed on wells with malfunctions.
Contamination Characterization (Ground Water Contamination)	Determine the horizontal and vertical concentration profiles of all constituents of potential concern (COPCs) in the groundwater that are measured by USEPA-approved procedures (B.3.C.1(d)). COPCs are those chemicals that have been detected in groundwater in the past and their daughter (breakdown) products.	Groundwater samples were collected from wells: CS-1, CS-2, CS-4, CS-9, CS-10, CS-11, CS-MW16-LGR, CS-MW16-CC, CS-D, CS-MWG-LGR, CS-MWH-LGR, CS-I, 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-MW11B-LGR, CS-MW12-LGR, CS-MW12-BS, CS-MW12-CC, CS-MW17-LGR, CS-MW18-LGR, and CS-MW19-LGR. Samples were analyzed for the selected VOCs using USEPA method SW8260B. Newly installed and drinking water wells were analyzed for arsenic, cadmium, and lead by SW6020, mercury by SW7470, and barium, chromium, copper, nickel, and zinc by SW6010B. Anions and cations were also collected from the newly installed well. Analyses were conducted in accordance with the AFCEE QAPP and approved variances. All RLs were below MCLs, as listed below:	Yes.	NA.
		Analyte RL (ug/L) MCL (ug/L) Chloroform 0.4 100 Chloromethane 1.3 -- Dibromochloromethane 0.5 100 1,1-DCE 1.2 7 cis-1,2-DCE 1.2 70 trans-1,2-DCE 0.6 100 Methylene Chloride 2 5 PCE 1.4 5 TCE 1.0 5
		Analyte RL (ug/L) MCL (ug/L) Barium 5 2000 Chromium 10 100 Copper 10 1300 Nickel 10 100 Zinc 10 11000 Arsenic 5 50 Cadmium 1 3 Lead 2 15 Mercury 1 2
Contamination Characterization (Ground Water Contamination) (Continued)	Meet AFCEE QAPP quality assurance requirements.	Samples were analyzed in accordance with the AFCEE QAPP and approved variances. All data were verified by a chemist.	Yes.	NA
		All data flagged with a �U,� �J,� and �F� are usable for characterizing contamination. All �R� flagged data are considered unusable.	Yes.	NA
		Previously, an MDL study for arsenic, cadmium, and lead was not performed within a year of the analyses, as required by the AFCEE QAPP.	The laboratory performed new MDL studies in February 2001 for these metals and the new MDL values were found to be almost identical to the previous MDLs and all met the associated AFCEE QAPP requirements. MDLs for these three metals are well below MCLs. In addition, the laboratory performed daily calibrations and RL verifications for these metals, both of which demonstrate the laboratory�s ability to detect and quantitate these metals at RL levels. These daily analyses also indicate that concentrations above the laboratory RL for these compounds were not affected by the expired MDL study.	Use results for groundwater characterization purposes.

Appendix B Quarterly On-Post Groundwater Monitoring Analytical Results, September 2003

	Differences in well completion depths and formations screened;
	Differences in recharge rates due to increased secondary porosity associated with the Salado Creek area;
	Differences in recharge rates due to increased secondary porosity associated with local fault zones;
	Pumping from public and private water supply wells located on- and off-post; and
	Locations of major faults or fractures.

	CS-D � Concentrations of PCE (220 �g/L), TCE (300 �g/L), and cis-1,2-DCE (270 �g/L) all exceeded the applicable MCL. Also detected were trans-1,2-DCE (0.93 �g/L), chloroform (0.23 �g/L) and vinyl chloride (0.062 �g/L) which were below the RL.
	CS-MW16-LGR � Concentrations of PCE (12.0 �g/L) and TCE (11.0 �g/L) exceeded the applicable MCL. Also detected were cis‑1,2-DCE at 8.6 �g/L and trans-1,2-DCE at 0.27 �g/L, cis-1,2-DCE was above the RL and trans-1,2-DCE was below the RL.
	CS-MW16-CC � Concentrations of PCE (33.0 �g/L), TCE (78.0 �g/L), and cis-1,2-DCE (93.0 �g/L) all exceeded the applicable MCL. Also detected were trans-1,2-DCE at a concentration of 4.4 �g/L and vinyl chloride at a concentration of 1.3 �g/L. Trans-1,2-DCE was below the RL while vinyl chloride was above the RL.
	CS-MW1-LGR � PCE and TCE concentrations were 11.0 �g/L and 26.0 �g/L and were above the applicable MCL. Also detected were cis-1,2-DCE at 17.0 �g/L, trans-1,2-DCE at 0.22 �g/L, and chloroform at 0.12 �g/L. Trans-1,2-DCE and chloroform were below the RL, while cis-1,2-DCE was above the RL.

	An average decrease in water levels of 52.85 feet occurred between June 2003 and September 2003. CSSA had 8.05 inches of rainfall between June 17, 2003 and September 22, 2003. Rainfall events during the 3-month period fell mainly in early July and September. One rainfall event on September 4, 2003 exceeded 1 inch during a 24-hour period.
	The LGR groundwater potentiometric surface map (Figure 2-1) for June 2003 shows groundwater flow to be variable throughout the facility; in the southwest corner of the facility, groundwater flow is to the southwest and south. Flow in other areas of CSSA is generally to the south and southeast, with exceptions at the central portion of CSSA. Groundwater extraction from both on- and off-post drinking water supply wells, varying rates of recharge from rain events, and the inherent complexity of groundwater flow in a fractured limestone aquifer, all contribute to difficulties in interpreting the potentiometric surface at CSSA.
	The LGR potentiometric surface map near Building 90 indicates a groundwater flow to the south in September 2003. The flow direction in the CC is to the north in September 2003.
	One newly-installed well was sampled during this event (CS-MW16-CC). Detections of PCE (33.0 mg/L), TCE (78.0 mg/L), and cis-1,2-DCE (93.0 mg/L) occurred, above the applicable MCLs.
	Four wells had detections above the applicable MCL for some or all of PCE, TCE, and cis‑1,2-DCE. Wells CS-MW16-LGR, and CS-MW1-LGR exceeded the MCL for PCE and TCE only and CS-D and CS-MW16-CC exceeded the MCL for all three.
	Seven other wells had detections of VOCs above the RL for one or more of the following analytes: PCE, TCE, toluene, chloroform, cis-1,2-DCE. These wells consisted of monitoring, livestock, and drinking water wells CS-MWH-LGR, CS-I, CS-4, CS-10, CS-MW1-BS, CS‑MW5-LGR, and CS-MW10-LGR.
	Nineteen other wells had VOC concentrations detected above the MDL, but below the RL (F flagged results) for one or more of the following analytes: chloroform, chloromethane, cis-1,2-DCE, PCE, TCE, vinyl chloride, naphthalene, and toluene. These wells consisted of monitoring and livestock wells CS-2, CS-MW1-CC, CS-MW2-LGR, CS-MW2-CC, CS‑MW4-LGR, CS-MW6-BS, CS-MW7-LGR, CS-MW8-LGR, CS-MW8-CC, CS-MW9-LGR, CS-MW11A-LGR, CS-MW11B-LGR, CS-MW12-CC, CS-MW12-BS, CS-MW17-LGR, and CS-MW18-LGR, CS‑MW19-LGR and drinking water wells CS-1 and CS-9.
	Ten wells had no VOC detections above the MDL for any analyte (CS-11, CS-MWG-LGR, CS-MW3-LGR, CS-MW6-LGR, CS-MW6-CC, CS-MW7-CC, CS-MW9-BS, CS-MW9-CC, CS-MW10-CC, and CS-MW12-LGR).
	On-post drinking water wells CS-1, CS-9, and CS-10 each had a detection of PCE above the MDL at concentrations of 0.084 mg/L, 0.05 �g/L, and 0.099 �g/L, respectively. TCE exceeded the MDL in CS-1 at a concentration of 0.37 �g/L.
	PCE concentrations increased this quarter in monitoring wells CS-2, CS-D, CS-MW1-LGR, CS-MW7-LGR, CS-MW8-LGR, CS-MW11A-LGR, and CS-MW19-LGR and drinking water well CS-10.
	TCE concentrations increased this quarter in monitoring wells CS-D, and drinking water well CS-1.
	No monitoring wells had an increase in cis-1,2-DCE concentrations this quarter.
	PCE concentrations decreased this quarter in monitoring wells CS-4, CS-MW2-LGR, CS-MW4-LGR, CS-MW5-LGR, CS-MW9-LGR, CS-MW16-LGR, CS-MW11B-LGR, and CS-MW17-LGR, as well as in drinking water wells CS-1 and CS-9.
	TCE concentrations decreased this quarter in monitoring wells CS-4, CS-MW1-BS, CS-MW2-LGR, CS-MW4-LGR, CS-MW5-LGR, CS-MW10-LGR, and CS-MW16-LGR.
	Cis-1,2-DCE concentrations decreased this quarter in monitoring wells CS-4, CS-MW1-BS, CS-MW2-LGR, CS-MW4-LGR, CS-MW5-LGR, and CS-MW16-LGR.
	Figure 6-1, Figure 6-2, and Figure 6-3 are included for evaluation of the concentrations of PCE, TCE, and cis-1,2-DCE over time in wells where these compounds have exceeded the MCL (CS-D, CS-MW16-LGR, CS-MW1-LGR, and CS-MW2-LGR). Concentrations have varied greatly over time with a significant increasing trend over the last three months of groundwater monitoring in well CS-D. PCE, TCE, and cis-1,2-DCE concentrations in well CS-MW16-LGR decreased significantly over the last three months. Concentrations of PCE and TCE in well CS‑D were the highest since the well was first sampled in December 1991. Well CS-MW1-LGR concentrations have remained relatively constant, while CS-MW2-LGR concentrations decreased over the last 3 months.
	Metals were sampled in September 2003 in drinking water wells and the newly installed well CS-MW16-CC and no concentrations were above the appropriate MCL, AL, or secondary standard.
	Vinyl chloride was detected for the first time in one well in December 2002. During the March 2003 event, seven wells had detections for vinyl chloride. During June 2003, only CS-MW1-BS, CS-MW1-CC, and CS-MW12-BS had detections of vinyl chloride. The September 2003 event reported vinyl chloride in 3 wells (CS-D, CS-MW16-CC, CS-MW1-BS). All detections of vinyl chloride have been below the RL and F flagged with the exception of CS-MW16-CC in the September 2003 event, which had a concentration of 1.3 μg/L.