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Final March 2004 On-Post Quarterly Groundwater Monitoring Report

Section 5 - March 2004 Analytical Results

On-post groundwater sampling was performed March 8-17, 2004. Thirty-two on-post wells were sampled using dedicated low-flow pumps: CS‑2, 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‑MW12‑LGR, CS‑MW12‑BS, CS‑MW12‑CC, CS‑MW16‑LGR, CS‑MW16-CC, CS‑MW17‑LGR, CS‑MW18‑LGR, and CS‑MW19‑LGR. Four wells, CS‑1, CS‑10, CS‑11, and CS‑MWH‑LGR, were sampled using high capacity submersible pumps. One additional sample (CS‑4) was collected from a monitoring well near well CS‑2. One sample was collected from the windmill (CS‑I) which was equipped with a solar-powered submersible pump in September 2003. Well CS‑9 was not sampled due to an electrical malfunction. The water level in well CS‑MW11B‑LGR was below the level of the low-flow pump; therefore, no sample could be collected.

The analytical program for on-post monitoring wells includes short-list 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 2004 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 known waste disposal records and process knowledge. 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.

The Parsons data package numbers TO 0008 #17 through #21 containing the analytical results from this sampling event were received by Parsons from April 1-12, 2004. Data validation was conducted and submitted to AFCEE April 19, 2004. AFCEE approval is pending. All detected concentrations of VOCs are presented in Table 5-1. Results for cadmium were flagged with an �R� in accordance with the CSSA QAPP, due to a laboratory quality assurance check. All sample results for cadmium were non-detect and are considered usable. 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 in a sample, it was also present in the analysis method blank, indicating the likelihood that this 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 every sample during the March 2004 sampling event and was present in the analysis method blanks as well.

Toluene was detected in the March 2004 sampling event at concentrations ranging from 0.13 �g/L to 8.1 �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. Based on a review of the data and the sample packaging procedures, it was concluded that the low-level concentrations detected in the March 2003 event were likely introduced by volatilization of toluene on tape used to label sample bottles. Contaminant-free tape was used during the June through March 2004 sampling events, and subsequently toluene was detected at decreased concentrations and frequency.

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 March 2004 event. The detected concentrations are summarized as follows:

Wells in which the contaminants of concern (COC) were exceeded were plotted for concentration trends over time and are shown in Figure 5-1 and Figure 5-2. Well CS‑MW16‑CC, installed December 20, 2002, is not included in these figures. Concentration trends from 1991 to the date of this report for CS‑MW16‑LGR and CS‑D are given in Figure 5-1, and in Figure 5-2 from 1998 through March 2004 for CS‑MW16‑LGR, CS‑D, CS‑MW1‑LGR and CS‑MW2‑LGR. CS‑MW16-LGR concentrations from the March 2004 event decreased slightly since December 2003. In March 2004 concentrations in well CS‑D decreased from the maximum detection (December 2003) since monitoring began in 1991. Wells CS‑MW1‑LGR and CS‑MW2‑LGR have been monitored since 1998, and both trend graphs show increases in concentrations in early 2001 and a decline in concentrations from September 2001 to September 2002. In March 2004 the concentrations in well CS‑MW2‑LGR and CS-MW1-LGR showed a slight decrease.

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.

Wells CS‑MWH‑LGR, CS-MWG-LGR, and CS‑I had detections of methylene chloride, but no other VOCs were detected.

Well CS‑2 had detections of PCE, trans-1,2-DCE, and 1,1-DCE at concentrations of 0.17 �g/L, and 0.03 �g/L, respectively. This is the fourth consecutive event with a PCE detection. All detections were below the RL.

Well CS‑4 had detections of PCE, TCE, trans-1,2-DCE, and 1,1-DCE at concentrations of 0.82 �g/L, 0.65 �g/L, 0.04 �g/L, and 0.03 �g/L, respectively. These concentrations were below the RL. PCE and TCE have been detected in this well since 1992; however, concentrations remain below the MCL.

CS‑MW1‑BS had detections of TCE (0.056 �g/L) and cis-1,2‑DCE (0.12 �g/L). Both detections were below the RL. Well CS-MW1‑CC had a detection of trans-1,2-DCE (0.04 �g/L) and 1,1‑DCE (0.03 �g/L), both detections were below the RL. This was the first detection of the aforementioned VOCs in well CS‑MW1‑CC.

CS-MW2‑LGR had detections of three VOCs. PCE, TCE, and cis‑1,2-DCE were detected at concentrations of 0.65 �g/L, 0.71 �g/L, and 0.73 �g/L, respectively. All detections were below the RL. Well CS‑MW2‑CC was sampled for the fourth time this quarter. The well had two VOC detection of toluene and methylene chloride, but no other VOCs were detected.

Well CS‑MW3‑LGR continued to have no detections this quarter, with the exception of methylene chloride. CS‑MW4‑LGR had detections of PCE (0.062 �g/L), TCE (0.057 �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, cis-1,2-DCE, and trans-1,2-DCE. PCE was detected at a concentration of 1.5 �g/L, TCE was detected at 2.4 �g/L, cis-1,2-DCE was detected at 2.6 �g/L, and trans-1,2-DCE was detected at 0.052 �g/L. All detections were above the RL with the exception of trans-1,2-DCE which was below the RL.

In March 2004, wells CS‑MW6‑LGR, CS‑MW6‑BS, CS‑MW6‑CC had detections of toluene, but no other VOCs were detected.

Well CS‑MW7‑LGR had three VOC detections, TCE at a concentration of 0.037 �g/L, trans-1,2-DCE at a concentration of 0.04 �g/L, and 1,1-DCE at a concentration of 0.03 �g/L, below the applicable RLs. Well CS‑MW7‑CC had two VOC detections of trans-1,2-DCE at a concentration of 0.04 �g/L and 1,1-DCE at a concentration of 0.03 �g/L, below the applicable RLs.

Well CS‑MW8‑LGR had a detection of PCE at a concentration of 0.59 �g/L, below the RL. Methylene chloride was detected in well CS‑MW8‑CC, but no other VOCs were detected.

Well CS‑MW9‑LGR had one VOC detection of PCE (0.15 �g/L, below the RL). Well CS‑MW9-BS and CS-MW9-CC had detections of methylene chloride, but no other VOCs were detected.

CS‑MW10‑LGR had detections of PCE, TCE, and chloroform at concentrations of 2.0 �g/L, 0.42 �g/L, and 0.11 �g/L, respectively. PCE was above the RL and below the MCL while the TCE and chloroform were below the RLs. Well CS-MW10-CC had a detection of methylene chloride, but no other VOCs were detected.

Well CS‑MW11A‑LGR was sampled for the fourth time in March 2004. Well CS‑MW11A‑LGR reported a detection of PCE (0.27 �g/L) below the RL. The water level in well CS‑MW11B‑LGR was below the low flow gas-operated bladder pump; therefore, no sample could be collected from this well.

Methylene chloride was the only VOC detected in CS‑MW12‑LGR. CS‑MW12‑BS had detections of naphthalene, toluene, and vinyl chloride at concentrations of 0.23 �g/L, 0.18 �g/L, and 0.099 �g/L, all below the applicable RLs. CS‑MW12‑CC had a detection of toluene at a concentration of 3.3 �g/L, above the RL and below the MCL. PCE was detected in well CS‑MW17‑LGR at a concentration of 0.18 �g/L, below the RL. Well CS‑MW18‑LGR had a detection of toluene, but no other VOCs were detected. Well CS‑MW19‑LGR had a detection of PCE (0.27 �g/L) below the RL.

In summary, wells CS‑2, CS‑4, CS‑MW1‑BS, CS‑MW1‑CC, CS‑MW2‑LGR, CS‑MW4‑LGR, CS‑MW5‑LGR, CS‑MW7‑LGR, CS‑MW7‑CC, CS‑MW8‑LGR, CS‑MW9‑LGR, CS‑MW10‑LGR, CS‑MW11A‑LGR, CS‑MW12‑BS, CS‑MW17‑LGR, and CS‑MW19‑LGR had detections of analytes below the MCL. Wells CS‑I, CS‑MWG‑LGR, CS‑MWH‑LGR, CS‑MW2‑CC, CS‑MW3‑LGR, CS‑MW6‑LGR, CS‑MW6‑BS, CS‑MW6‑CC, CS‑MW8‑CC, CS‑MW9‑BS, CS‑MW9‑CC, CS‑MW10‑CC, CS‑MW12‑LGR, CS‑MW12‑CC, and CS‑MW18‑LGR had no VOC analytes detected (other than methylene chloride and/or toluene) above either the MDL or RL.

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 March 2004 were CS‑1, CS‑10, and CS‑11. Well CS‑9 was not sampled due to an electrical malfunction. All contaminant concentrations detected in these wells were below MCLs.

CS‑1 had detections of PCE and TCE at concentrations of 0.086 �g/L and 0.15 �g/L, respectively. All concentrations were below the RL. PCE and TCE concentrations remained constant with sporadic detections of chloroform and toluene. March 2004 was the eighth consecutive detection of PCE (all F‑flagged) and the 19th consecutive detection of TCE (all F‑flagged).

Well CS‑10 had detections of chloroform and methylene chloride at concentrations of 0.20 �g/L and 0.61 �g/L; both were below the RL. Well CS‑11 (a former drinking water well) had detections of 1,1-DCE and trans-1,2-DCE at concentrations of 0.03 �g/L and 0.04 �g/L, respectively. Both detections were below the RL. This is the first detection of trans-1,2-DCE and the second detection of 1,1-DCE in this well since it was first sampled in August 1991.

5.2 - Metals Analyses

All monitoring and drinking water wells were analyzed for the metals arsenic, cadmium, lead, barium, chromium, copper, nickel, zinc, and mercury in June 2003. Results for cadmium were flagged with an �R� in accordance with the CSSA QAPP, due to a laboratory quality assurance check. The interference check (ICSA/ICSAB) analyzed at the end of the batch indicated cadmium above the RL of 0.002 mg/L, a possible high bias. However, all sample results for cadmium were non-detect and are considered usable. The next annual post-wide sampling event for metals will be conducted in June 2004. Only the drinking water wells were sampled for metals in March 2004, and none had a metals result above the appropriate MCL, action level (AL), or secondary standard.

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