All objectives listed in Table 1.1, Sampling Rationale for September 2003, were accomplished.  All wells scheduled to be sampled for the September event were sampled with the exception of JW-31.  The JW-31 well owners declined to take part in the sampling effort. 

Twenty-one wells reported detections of VOCs in September 2003.  Of the wells with VOC detections, two wells had concentrations above the MCL for PCE and TCE.  Wells OFR-3 and RFR-10 had detections of PCE and TCE above the MCLs of 5.0 �g/L.  OFR-3 also had a detection of dichlorodifluoromethane above the RL, but below the EPA health advisory level.  These wells have been equipped with GAC filtration systems. 

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

Fourteen 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, chloroform, and toluene. These analytes were detected in wells FO-J1, HS-2, JW-7, JW-8, JW-14, JW-26, JW-28, JW-30, LS-1, LS-4, LS-5, OFR-1, OFR-2, and RFR-12.

Six wells had no detections of the short list of VOCs:  I10-2, I10-4, JW-9, JW-29, OFR-4, and RFR-9.

No detections of the short list of VOCs occurred in post GAC samples collected from (LS-6, LS-7, OFR-3, RFR-10, and RFR-11).  The post GAC sample collected from LS-2/LS-3 had a detection of chloroform, below the MCL and RL, but above the MDL.

PCE concentrations decreased in September 2003 in wells HS-2, JW-8, JW-26, JW-29, LS-1, LS-3, LS-4, LS-6, LS-7, OFR-2, and RFR-11.  These decreases ranged in magnitude from 0.05 mg/L (JW-8) to 2.07 mg/L (RFR-11).

TCE concentrations decreased in wells LS-1, LS-3, LS-7, and RFR-12. These decreases were minor, ranging from 0.04 mg/L (LS-7) to 0.43 mg/L (LS-1).

PCE concentrations increased in wells FO-J1, OFR-1, OFR-2, OFR-3, and RFR-10.  The increases were less than 0.07 mg/L in FO-J1 and OFR-1.  OFR-3 increased by 7.23 mg/L.

TCE concentrations increased in wells LS-2, LS-5, LS-6, OFR-3, RFR-10, and RFR-11.  The increases ranged from 0.01 mg/L (LS-2 and LS-5) to 3.60 mg/L (OFR-3).

Two new wells were added to the quarterly monitoring in September 2003 (JW-7 and JW-28).  PCE was reported in well JW-7 at a concentration of 0.54 �g/L and toluene was reported in JW-28 at 0.13 mg/L.

Historical off-post detections of chloroform have rarely been above the RL.  The detections that have occurred do not correlate with those wells which have exceedances of the MCL for PCE or TCE.  Chloroform is a common disinfection by-product and laboratory contaminant.  For the September 2003 event, chloroform was detected below the RL (F-flagged) at concentrations ranging from 0.10 �g/L to 0.26 �g/L in ten of the twenty-seven wells that were sampled.

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 upcoming December 2003 event.  Prior to GAC installation, these wells were sampled on a monthly basis.  Since a GAC system has been installed, the wells will be sampled quarterly. 

Wells with detections above 80 percent of the applicable MCLs are required to be sampled on a monthly basis in accordance with the Plan.  Based on this criterion, no wells sampled during the September 2003 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 (FO-J1, HS-2, JW-7, JW-8, JW-14, JW-26, JW-28, JW-30, LS-1, LS-4, LS-5, OFR-1, OFR‑2, and RFR-12) in September 2003 will continue to be sampled on a quarterly basis, including the December 2003 event in accordance with Plan requirements.  Depending on concurrence by regulatory agencies, the sampling frequency may then be reduced.

Post-GAC confirmation samples will be collected at all off-post wells with GAC systems during the March 2004 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 December 2003, wells where no VOCs were detected may be sampled as needed.  September 2003 wells with no VOCs detected include I10-2, I10-4, JW-9, JW-29, OFR-4, and RFR-9. 

In the event additional wells are located to the west and southwest of AOC‑65, 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) to confirm they meet drinking water standards. 

In accordance with project DQOs, the rationale for selection of wells to be sampled in December 2003 is provided in Table 4.1.