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June 2004 Off-Post Quarterly Groundwater Monitoring Report
Section 2 - Groundwater Monitoring Procedures
Off-post groundwater monitoring was performed June 7 through 10, 2004. Thirty-two off-post wells were sampled during the June 2004 quarterly monitoring event, and their locations are illustrated in Figure 1.1. Off-post wells sampled during this quarterly monitoring event were selected based on previous sampling results and proximity to both the CSSA boundary and wells with detections of PCE and TCE. Public and private supply wells located west and south of CSSA were selected for this event. Table 1.1 illustrates the rationale for selection of wells for sampling based on the Plan and project DQOs. Thirty-three wells were recommended for sampling in the June 2003 Off-post Quarterly Groundwater Monitoring Report, and one well (FO-J1) was not sampled because of an electrical malfunction at the breaker box controlling the well pump.
Off-post wells sampled in June 2004 include (see Figure 1.1 for well locations):
| One public supply well in the Fair Oaks area (FO-17); | |
| Two public well in the Hidden Springs Estates subdivision (HS-2 and HS-3); | |
| Three private wells in the Interstate I-10 area (I10-2, I10-4, and I10-7); | |
| Eleven privately-owned wells in the Jackson Woods subdivision (JW-6, JW-7, JW-8, JW-9, JW-13, JW-14, JW-26, JW-27, JW-28, JW-29, and JW-30); | |
| Seven wells in the Leon Springs Villa area (four public wells: LS-1, LS-2, LS-3, and LS-4; and three privately-owned wells: LS-5, LS-6, and LS-7); | |
| Privately-owned wells on Old Fredericksburg Road (OFR-1, OFR-2, and OFR-3); and | |
| Five privately-owned wells in the Ralph Fair Road area (RFR-3, RFR-8, RFR‑10, RFR-11, and RFR‑12). |
All wells were sampled from a tap located as close to the wellhead as possible. Most taps were installed by CSSA to obtain a representative groundwater sample before pressurization, storage, or the water supply distribution system. Water was purged to engage the well pump prior to sample collection. Conductivity, pH, and temperature readings were recorded to confirm adequate purging while the well was pumping. Purging measurements are attached in Appendix D. Generally, this required an average of 20 gallons to be purged prior to sample collection. In accordance with the Field Sampling Plan (FSP), adequate purging has occurred when these parameters stabilize.
Thirty-two groundwater samples, three field duplicate samples, two matrix spike/matrix spike duplicate (MS/MSD) pairs, and two trip blanks were submitted to APPL Laboratory (APPL) in Fresno, California for analysis. Groundwater samples were analyzed for the short list of VOCs using SW-846 Method 8260. The EPA-approved short list of VOCs includes bromodichloromethane, bromoform, chloroform, dibromochloromethane, dichlorodifluoromethane, cis-1,2-dichloroethene (cis-1,2-DCE), trans‑1,2‑DCE, 1,1-DCE, methylene chloride, naphthalene, PCE, TCE, toluene, and vinyl chloride. This list represents analytes that were detected in on-post groundwater samples or analytes which may result from natural degradation of the detected on-post compounds.
The Parsons internal data packages (TO08-#33 and -#34) contain the analytical results for this sampling event. Laboratory results were reviewed and verified according to the guidelines outlined in the CSSA Quality Assurance Project Plan (QAPP). Data packages were received by Parsons on June 30, 2004 and July 2, 2004, and the data verification reports were submitted to AFCEE on July 16, 2004. AFCEE approval of these data packages is pending.