[Home] [Master Table of Contents]
[Report Table of Contents] [Next Section]
Final June 2002 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 June 17, 2002, at Camp Stanley Storage Activity (CSSA). 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 Order 67, Delivery Order (DO) 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 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. Overall DQOs for the investigations at CSSA are provided in Volume 1-1 behind the RFI Addendum tab (Section 11).
Twenty-nine water level measurements were recorded during the June 2002 monitoring event. Water level measurements were taken in CSSA wells CS-1, CS-2, CS-3, CS-4, CS-9, CS-10, CS-11, CS-16, CS-D, CS-G, CS-H, CS-I, CS-MW1-LGR, CS-MW2-LGR, CS-MW3-LGR, CS-MW4-LGR, CS-MW5-LGR, CS-MW6-LGR, CS-MW6-CC, CS-MW6-BS, CS-MW7-LGR, CS-MW7-CC, CS-MW8-LGR, CS-MW8-CC, CS-MW9-LGR, CS-MW9-CC, CS-MW9-BS, CS-MW10-LGR, and CS-MW10-CC. All water levels were measured with an e-line water level indicator. Transducer data was collected from wells CS-16, CS-MW9-LGR, CS-MW9-BS, and CS-MW9-CC. No data was collected from the transducer in CS-MW4-LGR due to technical malfunction. Transducer data is discussed in Section 3. An average groundwater elevation for well FO-20 from the week of June 17, 2002 was obtained from Fair Oaks Water Utilities.
On average, groundwater levels decreased 50.08 feet between the last on-post monitoring event, March 11, 2002 and June 17, 2002. This overall decrease was calculated by averaging the groundwater elevation changes for all wells, including those screened across multiple formations. Groundwater depths derived from water level measurements are compared to top of casing elevations and are summarized in Table 1-1. Table 1-2 summarizes the changes in groundwater elevations since the March 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 each formation in the middle Trinity aquifer is provided in Table 1-1, calculated by using the groundwater elevations from wells screened only in that unit. At CSSA, the Lower Glen Rose overlies the Bexar Shale and Cow Creek, respectively. As indicated on Table 1-1, only those wells screened in a single formation/unit are included when calculating the average water level in each formation. Typically, the water levels measured at CSSA decrease from the Lower Glen Rose to the Bexar Shale to the Cow Creek. The average groundwater elevations in June 2002 for the Lower Glen Rose, Bexar Shale, and Cow Creek were 1030.51 feet, 1022.51 feet, and 994.02 feet, respectively, a decrease of 47.40 feet in the Lower Glen Rose, 41.95 feet in the Bexar Shale, and 65.25 feet in the Cow Creek from the average levels measured in March 2002. Evaluation of trends in water level elevations in the different units will continue as additional wells are installed.