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September 2004 On-Post Quarterly Groundwater Monitoring Report

Section 5 - September 2004 Analytical Results

On-post groundwater sampling was performed September 7-17, 2004.  Thirty-three on-post wells were sampled using dedicated low-flow pumps:  CS‑2, CS-4, CS‑D, CS‑MWG‑LGR, CS‑MW1‑LGR, CS‑MW1‑BS, CS-MW1‑CC, CS‑MW2‑LGR, CS‑MW2‑CC, CS‑MW3‑LGR, CS‑MW4‑LGR, CS‑MW5‑LGR, CS‑MW6‑LGR, CS‑MW6‑BS, CS‑MW6‑CC, CS‑MW7‑LGR, CS‑MW7‑CC, CS‑MW8‑LGR, CS‑MW8‑CC, CS‑MW9‑LGR, CS‑MW9‑BS, CS‑MW9‑CC, CS‑MW10‑LGR, CS‑MW10‑CC, CS‑MW11A‑LGR, CS‑MW11B‑LGR, CS‑MW12‑LGR, CS‑MW12‑BS, CS‑MW12‑CC, CS‑MW16‑LGR, CS‑MW17‑LGR, CS‑MW18‑LGR, and CS‑MW19‑LGR.  Five wells, CS‑1, CS-9, CS‑10, CS-MW16-CC and CS‑MWH‑LGR, were sampled using high capacity submersible pumps.  One sample was collected from the windmill (CS‑I) that was equipped with a solar-powered submersible pump in September 2003.  Well CS-11 was not sampled due to an electrical malfunction.  Samples were collected after field parameters stabilized.  For stabilization logs from the In-Situ Rugged Reader see Appendix C.

The analytical program for on-post monitoring wells includes short-list volatile organic compound (VOC) analysis.  Samples from the drinking water supply wells (CS‑1, CS-9, and CS‑10) were analyzed for the full list of VOCs, as well as nine metals.  On-post monitoring wells are analyzed for metals once annually.  The June 2005 event is the next scheduled annual sampling for metals, including arsenic, cadmium, lead, barium, chromium, copper, nickel, zinc, and mercury.  These nine metals were chosen based on CSSA�s waste disposal records and process knowledge.  As part of the September 2004 sampling event on-post monitoring wells were analyzed for the short list of VOC analytes, including bromodichloromethane, bromoform, chloroform, dibromochloromethane, dichlorodifluoromethane, 1,1‑dichloroethene (DCE), cis-1,2‑DCE, trans-1,2‑DCE, methylene chloride, naphthalene, PCE, TCE, toluene, and vinyl chloride.

Parsons data package numbers TO 0008 #58 through #62 containing the analytical results from this sampling event were received by Parsons from September 27, 2004 to October 1, 2004.  Data validation was conducted and submitted to AFCEE on October 13, 2004.  AFCEE approved the data packages on October 20 004.  All detected concentrations of VOCs are presented in Table 5‑1.  Full analytical results are presented in Appendix B.  Cumulative analytical results can be found in Tables 6 and 7 of the Introduction to the Quarterly Groundwater Monitoring Program (Parsons, 2001) (Volume 5, Groundwater).

5.1 - Volatile Organic Compound Results

5.1.1   Toluene and Methylene Chloride Detections

Methylene chloride has been reported periodically in samples from both on- and off-post wells since 1992.  Each time methylene chloride was detected, it was also present in the analysis method blank, indicating the analyte was introduced as a laboratory contaminant and was not present in the groundwater.  Methylene chloride is considered a common laboratory contaminant and there are no known historical uses of methylene chloride on-post.  Methylene chloride was detected in all but two samples during the September 2004 sampling event.

Toluene was detected in the September 2004 sampling event at concentrations ranging from 0.062 �g/L to 1.8 �g/L.  These levels were below the applicable maximum contaminant level (MCL) for toluene in drinking water (1,000 μg/L).  Toluene has been detected sporadically in on-post wells since March 2003.

5.1.2   MCL Exceedances in Monitoring Wells

MCLs were exceeded in wells CS‑MW16‑LGR (formerly well CS‑16), CS-MW16-CC, CS‑MW1‑LGR and CS‑D in the September 2004 event.  The detected concentrations are summarized as follows:

Wells in which the contaminants of concern (COC) exceed MCLs were plotted for concentrations over time and are shown in Figure 5-1.  Well CS‑MW16‑CC, installed December 20, 2002, does not have results from 1998 through 2002.  CS‑MW16-LGR concentrations from the September 2004 event increased significantly since March 2004.  In September 2004 concentrations in well CS‑D decreased and are still below the maximum detection that occurred in December 2003.  In September 2004 the concentrations in well CS‑MW2‑LGR continued to decrease along with concentrations in well CS-MW1-LGR.  A remedial process optimization study will be conducted for the CSSA groundwater monitoring program.  This study will evaluate sampling frequency and analyte lists.  The preliminary statistical evaluation is being conducted.

5.1.3   Detections Below the MCL in Monitoring Wells

Additional wells had detections of COCs below applicable MCLs.  These wells are monitoring wells installed as part of the ongoing groundwater investigation.  Detections of methylene chloride and/or toluene are not discussed as additional information has been provided previously in Section 5.1.1.

Well CS-4 reported PCE, TCE, and cis-1,2-DCE at concentrations of 2.0 �g/L, 3.4 �g/L, and 1.7 �g/L which were above the applicable RL.  Also detected was trans-1,2-DCE  (0.061 �g/L) below the RL.  PCE and TCE have been detected in this well since 1992, June 2004 was the first time concentrations have exceeded the applicable MCLs.  The field duplicate reported similar results with concentrations of PCE, TCE, and cis-1,2-DCE above the RL at concentrations of 1.8 �g/L, 3.2 �g/L, and 1.6 �g/L , respectively.  Trans-1,2-DCE was below the RL at a concentration of 0.058 �g/L.

Wells CS-MWG-LGR and CS-MWH-LGR reported no VOC detections this quarter.  Well CS‑2 had a detection of PCE, naphthalene, and methylene chloride at concentrations of 0.096 �g/L, 0.09 �g/L, and 0.28 �g/L.  This is the sixth consecutive event with a PCE detection.  All detections are below the RL.

CS‑MW1‑BS had detections of TCE (0.062 �g/L) and cis-1,2‑DCE (0.21 �g/L).  Both detections are below the RL.  Toluene was detected above the RL at a concentration of 1.8 �g/L.  This is the fourth consecutive event TCE has been detected in this well.  Well CS‑MW1-CC had no VOC detections, other than methylene chloride and toluene, in September 2004.

CS-MW2‑LGR had detections of three VOCs.  PCE, TCE, and cis‑1,2-DCE were detected at concentrations of 0.12 �g/L, 0.25 �g/L, and 4.3 �g/L, respectively.  PCE and TCE were below RLs while cis-1,2-DCE was above the RL but below the MCL.  Well CS‑MW2‑CC was sampled for the sixth time this quarter.  The well had detections of toluene and methylene chloride, but no other VOCs were detected.

Well CS‑MW3‑LGR reported concentrations of PCE and TCE for the first time in September 2004, at concentrations of 0.062 �g/L and 0.056 �g/L.  Both concentrations were below the RL.  Well CS-I also had detections of PCE and TCE for the first time since first sampling the well in November 1992.  PCE was detected at a concentration of 0.054 �g/L and TCE at a concentration of 0.041 �g/L, both below the RL.

CS‑MW4‑LGR had detections of PCE (0.084 �g/L), TCE (0.062 �g/L), and cis-1,2‑DCE at a concentration of 0.19 �g/L, all below the RL.  CS‑MW5‑LGR had detections of PCE, TCE, and cis-1,2-DCE, (all were below the RL.)  PCE was detected at a concentration of 0.64 �g/L, TCE was detected at 0.72 �g/L, and cis-1,2-DCE was detected at 0.79 �g/L.

In September 2004 wells CS‑MW6‑LGR, CS‑MW6‑BS, and CS‑MW6‑CC and CS‑MW7-LGR had no VOC detections.  CS-MW7-CC had one VOC detection of 1,1-DCE (0.034 �g/L), below the RL.  1,1-DCE was last reported in this well in September 2002.  Due to the fact that 1,1-DCE was reported in three of the four trip blanks and the detection in well CS-MW7-CC has a similar result, this detection is most likely attributed to field or laboratory contamination and is probably not present in the groundwater.

Well CS‑MW8‑LGR had a detection of PCE at a concentration of 0.51 �g/L, below the RL.  PCE has been reported in this well since sampling began in June 2001, with the exception of December 2003.  All concentrations have been below the RL.  PCE was detected for the first time in well CS‑MW8‑CC (0.19 �g/L), was below the RL.  CS-MW8-CC has been sampled quarterly since June 2001.

Wells CS‑MW9‑LGR, CS-MW9-BS, and CS-MW9-CC had no VOC detections in September 2004.

CS‑MW10‑LGR had detections of PCE, TCE, chloroform, and naphthalene at concentrations of 2.1 �g/L, 0.37 �g/L, 0.11 �g/L, and 0.090 �g/L, respectively.  PCE was above the RL but below the MCL while the TCE, chloroform, and naphthalene were below RLs.  The CS-MW10-LGR field duplicated reported similar results.  Well CS-MW10-CC had detections of methylene chloride, naphthalene, and toluene all below the RL.  Methylene, chloride, and toluene are discussed in Section 5.1.1.

Well CS‑MW11A‑LGR was sampled for the sixth time in September 2004.  Well CS‑MW11A‑LGR reported a detection of PCE (0.29 �g/L) below the RL.  Well CS‑MW11B‑LGR reported a detection of PCE at a concentration of 1.1 �g/L, which is below the RL.  This is the fourth sample collected from this well since it was installed in June 2003.  PCE has been consistently reported below the RL in CS-MW11B-LGR.

No VOCs, other than methylene chloride and toluene, were detected in CS‑MW12‑LGR in September 2004.  CS‑MW12‑BS had detections of methylene chloride, naphthalene, toluene, and vinyl chloride at concentrations of 0.68 �g/L, 0.33 �g/L, 0.26 �g/L, and 0.21 �g/L, all below applicable RLs.  CS‑MW12‑CC had detections of methylene chloride (0.33 mg/L) and toluene (0.28 mg/L), both below the RL.

PCE and TCE were detected in well CS‑MW17‑LGR at concentrations of 0.34 �g/L and 0.067 �g/L, both below the RL.  Well CS‑MW18‑LGR reported its first detection of PCE at a concentration of 0.051 �g/L, below the RL.  The field duplicate reported similar results.  CS‑MW18-LGR has been sampled quarterly since September 2002.  Well CS‑MW19‑LGR had detections of PCE (0.28 �g/L) and naphthalene (0.09 �g/L), both below the RL.  PCE has been consistently detected below the RL in wells CS-MW17-LGR and CS-MW19-LGR since they were installed in September 2002.

5.1.4   Drinking Water Supply Well Results

Drinking water supply wells are analyzed for the full list of VOCs.  Current and former drinking water supply wells for CSSA sampled in September 2004 were CS‑1, CS-9, and CS‑10.  CS‑11 was not sampled this quarter due to an electrical malfunction.  All contaminant concentrations detected in these wells were below MCLs.

CS‑1 had detections of PCE, TCE, and 1,1-DCE at concentrations of 0.066 �g/L, 0.093 �g/L, and 0.053 �g/L, respectively.  All concentrations were below the RL.  PCE and TCE concentrations have remained constant with sporadic detections of chloroform, methylene chloride and toluene.  September 2004 was the tenth consecutive detection of PCE (all F‑flagged), the 21^st consecutive detection of TCE (all F‑flagged), and the first detection of 1,1-DCE.  1,1-DCE was also detected in three of the four trip blanks at similar levels, leading the chemist to believe that these detections can be attributed to field or laboratory contamination, 1,1-DCE is not likely present in the groundwater.

Well CS-9 had no VOC detections except for analytes mentioned in Section 5.1.1 (methylene chloride and toluene).  There have been five detections of PCE since the well was first sampled in August 1991.  All detections have been below the RL.

Well CS‑10 had detections of PCE, 1,1-DCE, chloroform, and methylene chloride at concentrations of 0.074 �g/L, 0.071 �g/L, 0.37 �g/L, and 0.36 �g/L; all were below RLs with the exception of chloroform which was above the RL but below the MCL.

5.2 - Metals Analyses

All drinking water wells were analyzed for the metals arsenic, cadmium, lead, barium, chromium, copper, nickel, zinc, and mercury in September 2004.  In September 2004, no drinking water wells had results above the appropriate MCL, action level (AL), or secondary standard.  The next annual post-wide sampling event for metals will be conducted in June 2005.

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