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March 2003 On-Post Quarterly Groundwater Monitoring Report
Section 1 - Water Level Measurements
Groundwater monitoring scoped under the Air Force Center for Environmental Excellence (AFCEE) 3P/AE Contract 41624-00-D-8024, Task Order (TO) 0042, was performed the week of March 17, 2003, at Camp Stanley Storage Activity (CSSA). On-post groundwater monitoring conducted under this TO began with the March 2002 sampling event and will continue through the June 2003 sampling event. Groundwater monitoring conducted prior to March 2002 was conducted under Delivery Orders (DOs) 67, 23, RL74, DO5084, and RL83. 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).
1.0 - Water Level Measurements
Thirty-six water level measurements were recorded on April 10, 2003. The water level measurements were not collected during the March 2003 sampling event, but are used for preparation of this report. Water level measurements were collected from CSSA wells CS-1, CS-2, CS-3, CS-4, CS-9, CS-10, CS-11, CS-MW16-LGR, CS-D, CS-MWG-LGR, CS-I, CS-MW1-LGR, CS-MW1-BS, CS-MW1-CC, CS-MW2-LGR, 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-MW12-LGR, CS-MW12-BS, CS-MW12-CC, CS-MW17-LGR, CS-MW18-LGR, and CS-MW19-LGR. Water levels were also measured on March 17, 2003, but three wells were inadvertently missed. The April data are included in this report because all 36 wells were measured on the same day. All water levels were measured with an e-line water level indicator. Transducer data was also collected from wells CS-MW16-LGR, CS-MW9-LGR, CS-MW9-BS, CS-MW9-CC, and CS-MW4-LGR. Transducer data is discussed in Section 3. An average groundwater elevation for well FO-20 during the week of April 10, 2003, was obtained from Fair Oaks Water Utilities.
On average, groundwater elevation levels for wells screened in the Lower Glen Rose (LGR) decreased 8.03 feet between December 10, 2002 and April 10, 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 December 2002 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 LGR, Bexar Shale (BS), and Cow Creek (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. However, in March 2003 the average groundwater elevation is highest for the BS, and decreases to the LGR then to the CC. The average groundwater elevations in April 2003 for the LGR, BS, and CC were 1135.18 feet, 1140.52 feet, and 1122.95 feet, respectively, a decrease of 8.03 feet in the LGR, 7.74 feet in the BS, and 10.16 feet in the CC from the average levels measured in December 2002. Evaluation of trends in water level elevations in the different formations will continue as additional wells are completed.