The objectives listed in Table 1.1 were accomplished except for sampling HS-1. All other wells scheduled to be sampled for the March event were sampled. Well HS-1 has not been placed into service by the well owner.

Twenty-one of the thirty-one wells sampled reported detections of VOCs in March 2005. Of the wells with VOC detections, one well had concentrations above the MCL for PCE and TCE. Well RFR‑10 had a detection of 8.03 �g/L PCE, which exceeds the MCL of 5.0 �g/L. Well RFR‑10 also had a detection of TCE at a concentration of 5.19 �g/L, also above the MCL, and cis-1,2-DCE at a concentration 0.43 �g/L, below the MCL and RL. RFR-10 was previously equipped with a GAC filtration system.

Six wells had detections of VOCs reported at concentrations below the MCL but above the RL for one or more of PCE and TCE. PCE and TCE were detected above the RL in LS-6; PCE was detected above the RL in wells LS‑2, LS‑3, LS‑7, and RFR-11; TCE was above the RL in well OFR-3. Wells LS‑2/LS‑3, LS‑6, LS‑7, RFR-11, and OFR‑3 have been equipped with GAC filtration systems.

Thirteen wells reported concentrations of VOCs above the MDL, but below the RL for one or more of the following analytes: PCE, TCE, cis-1‑2‑DCE, dichlorodifluoromethane, chloroform, and toluene. These analytes were detected in samples DOM-2, FO‑J1, HS‑2, I10‑2, JW‑7, JW‑8, JW‑14, JW‑14 FD, JW‑30, LS‑4, LS‑5, LS-5 FD, OFR‑1, RFR-4, and RFR‑12.

Well RFR-13 was sampled for the first time in December 2004. Initial results reported chloroform (54.1 mg/L), bromodichloromethane (5.0 mg/L), and dibromochloromethane (1.55 mg/L). These COCs are regulated as TTMs with a combined MCL of 80 mg/L. The well owner was interviewed and reported a self-performed disinfection using household bleach. A follow up sample was collected on January 11, 2005, with similar results: chloroform (64.52 mg/L), bromodichloromethane (8.74 mg/L), and dibromochloromethane (2.94 mg/L). The concentrations of combined trihalomethanes increased in the second sampling event. The well owner was informed of the results and directed to TCEQ guidance for the public on well disinfections. In March 2005 chloroform (17.38 mg/L), bromodichloromethane (1.47 mg/L), dibromochloromethane (1.52 mg/L), and bromoform (1.21 mg/L) were detected in RFR-13. These levels have decreased from the last sampling event. RFR-13 will continue to be monitored on a quarterly basis in accordance with the Plan.

Ten wells had no detections from the short list of VOCs: FO-8, I10‑4, I10‑7, JW‑9, JW‑12, JW‑28, JW‑29, JW-29 FD, OFR‑2, OFR‑4, and RFR‑5.

PCE concentrations decreased between December 2004 and March 2005 in ten wells: FO-J1, HS‑2, I10‑2, JW‑7, JW-8, JW‑30, LS‑6, OFR‑3, RFR‑10, and RFR‑11.

TCE concentrations decreased in ten wells: JW-8, JW-30, LS-2, LS-3, LS-5, LS-6, LS-7, OFR-3, RFR‑10 and RFR‑11.

PCE concentrations increased in three wells: LS‑2, LS-3, and LS‑7.

TCE concentrations increased in two wells: FO‑J1 and RFR‑12.

Post GAC samples were collected from wells (LS‑2/LS‑3, LS‑6, LS‑7, OFR‑3, RFR‑10, and RFR‑11) this quarter. All concentrations were below the applicable RL indicating the GAC filtration systems are working properly. Post-GAC samples will be collected again in September 2005.

In accordance with Plan requirements, wells with historical detections above 90 percent of the applicable MCL (LS‑2, LS‑3, LS‑6, LS‑7, OFR‑3, RFR‑10, and RFR‑11) will continue to be sampled on a quarterly basis, including the June 2005 event.

Wells with detections above 80 percent of the applicable MCLs are required to be sampled on a monthly basis in accordance with the Plan. No wells sampled during the March 2005 event will be sampled monthly. All wells with VOC detections greater than 80 percent of the applicable MCLs have GAC filtration systems installed and are already included in the quarterly monitoring.

Wells with detections of VOCs at less than 80 percent of the MCLs (DOM-2, FO‑J1, HS‑2, I10‑2, JW‑7, JW‑8, JW‑14, JW‑30, LS‑2, LS‑3, LS‑4, LS‑5, LS‑6, LS‑7, OFR‑1, OFR‑3, RFR-4, RFR‑10, RFR‑11, RFR‑12 and RFR‑13) in March 2005 will continue to be sampled on a quarterly basis, including the June 2005 event in accordance with Plan requirements. Depending on concurrence by regulatory agencies, the sampling frequency for these wells may be reduced in the future.

Post-GAC confirmation samples will be collected at all off-post wells with GAC systems during the September 2005 sampling event. This will include wells LS‑2, LS‑3, LS‑6, LS‑7, OFR‑3, RFR‑10, and RFR‑11.

For future sampling events, including June 2005, wells where no VOCs were detected may be sampled as needed, depending on historical detections. March 2005 wells with no VOCs detected include FO-8, I10-4, I10‑7, JW‑9, JW‑12, JW‑28, JW-29, OFR‑2, OFR-4, and RFR‑5.

In the event additional wells are located to the west and southwest of CSSA, they may be added to future sampling events. Future sampling events will continue to include wells to the west of CS‑D and CS‑MW16‑LGR (Fair Oaks and Jackson Woods Subdivision areas) to confirm they continue to meet drinking water standards.

In accordance with project DQOs, the rationale for selection of wells to be sampled in June 2005 is provided in Table 4.1.