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December 2002 Off-Post Quarterly Groundwater Monitoring Report
Section 2 - Groundwater Monitoring Procedures
Off-post groundwater monitoring was performed December 2 � 6, 2002. Twenty-six off-post wells were sampled during the December 2002 quarterly monitoring event (Figure 1.1). Twenty-seven samples were submitted for laboratory analysis, consisting of 26 individual well samples and one post-filtration sample. Off-post wells sampled during this quarterly monitoring event were selected based on previous sampling results and proximity to both the post 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. Figure 1.1 illustrates locations of off-post private and public wells sampled during the December 2002 quarterly event. Table 1.1 illustrates sampling rationale for selecting wells based on the Plan and project DQOs. All wells sampled in December 2002 were sampled previously as part of the quarterly groundwater program. No additional wells that would provide data in support of DQOs were identified for testing this quarter.
Off-post wells sampled in December 2002 include (see Figure 1.1 for well locations):
| Two public supply wells in the Fair Oaks area (FO-J1 and FO-22); | |
| One well in the Hidden Springs Estates subdivision, public well HS-2; | |
| Two private and one public supply well in the I-10 area (I10-2, I10-5, and I10-4); | |
| Five privately-owned wells in the Jackson Woods subdivision (JW-9, JW-12, JW-13, JW-14, and JW-26); | |
| 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 OFR-1, OFR-2 and OFR-3 on Old Fredericksburg Road; and | |
| Five privately-owned wells in the Ralph Fair Road area (RFR-3, RFR-6, RFR-10, RFR-11, and RFR‑12). |
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. 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 8260 by APPL Laboratory (APPL) in Fresno, California. Twenty-seven groundwater samples, three field duplicate samples, one matrix spike/matrix spike duplicate (MS/MSD) pair, and five trip blanks were submitted to APPL. The Parsons internal data package numbers TO 0042-48, 49, 50, 51, 52, 53 and 54 (groups J and K) contain the analytical results for this sampling event. Laboratory results were reviewed and verified according to the guidelines outlined in the AFCEE Quality Assurance Project Plan (QAPP), version 3.0. Data packages were received by Parsons between December 27, 2002 and January 6, 2003, and the data verification reports were submitted to AFCEE on January 6, 2003. AFCEE approval was received February 19, 2003.