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June 2002 Off-Post Quarterly Groundwater Monitoring Report
Section 2 - June 2002 Groundwater Monitoring Procedures
Twenty-five off-post wells were sampled during the June 2002 quarterly monitoring event (Figure 1.1). Quarterly off-post groundwater monitoring was performed from June 10 through June 13, 2002. Off-post wells sampled during this quarterly monitoring event were selected based on previous sampling results and proximity to the post boundary and to wells with detectable levels of PCE and TCE. Public and private supply wells located west and south of CSSA were selected for this round of quarterly off-post sampling. Figure 1.1 illustrates locations of off-post private and public wells sampled during the June 2002 quarterly event. Table 1.1 illustrates the sampling rationale for selecting wells based on the Plan and project DQOs. All wells sampled in June 2002 were sampled previously as part of the quarterly groundwater program. No additional wells that would provide data to support DQOs were identified for testing this quarter. However, an entry point sample was collected in Fair Oaks prior to entering the water distribution system to determine whether contaminants reach the system.
Based on the March 2001 and previous analytical data, granular activated carbon (GAC) wellhead treatment systems were installed at LS-2, LS-3, and OFR-3 during April 2002. Post treatment confirmation samples were collected from these wells in April 2002, to confirm VOC removal. No other off-post wells were identified for monthly or �out of cycle� sampling.
Off-post wells sampled in June 2002 include (see Figure 1.1 for well locations):
| One public supply well and the entry point to the water distribution system from this well in the Fair Oaks area (FO-J1 and FO-J1 EP); | |
| Three privately owned wells in the Jackson Woods subdivision (JW-9, JW-14, and JW-6); | |
| One private and one public supply well in the I-10 area (I10-2 and I10-4); | |
| Seven wells in the Leon Springs 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. | |
| Six wells in the Ralph Fair Road area (RFR-7, RFR-8, RFR-9, RFR-10, RFR-11, and RFR-12); | |
| Two wells in the Hidden Springs subdivision, public wells HS-2 and HS-3; and | |
| Privately owned wells OFR-1, OFR-2 and OFR-3 on Old Fredericksburg Road. |
All wells were sampled from a tap as close to the wellhead as possible. Most of the taps were installed by CSSA to obtain a representative groundwater sample before pressurization or storage and before it enters the water supply distribution system. Prior to sample collection, water was flushed to engage the well pump. While the well was pumping, the pH, conductivity, and temperature readings were measured and recorded to confirm adequate purging. Generally, this required an average of 20 gallons to be purged prior to sample collection from most wells. In accordance with the Field Sampling Plan (FSP), adequate purging is determined when these parameters stabilize. Field notes, including well purging data are included in Appendix C.
Each groundwater sample collected was analyzed for VOCs using SW846 Method 8260B by APPL Laboratory in Fresno, California (APPL). Twenty-five groundwater samples, two field duplicate samples, two Matrix Spike/Matrix Spike Duplicate (MS/MSD) pairs, and three trip blanks were submitted to APPL. The Parsons internal data packages DO5084 #29, #30, and #31 as well as RL83 #69 contain the analytical results for this sampling event. Laboratory results were reviewed and verified according to the guidelines outlined in the AFCEE QAPP, version 3.0. Data packages were received by Parsons July 3, 2002, and all packages were submitted to AFCEE on July 17, 2002, and AFCEE approval was received August 13, 2002.