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Section 5 - December 2003 Analytical Results
On-post groundwater sampling was performed December 8-16, 2003. Thirty-one 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‑MW17‑LGR, CS‑MW18‑LGR, and CS‑MW19‑LGR. Five wells, CS‑1, CS‑9, 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. A sample was not collected from CS‑MW16‑CC due to road construction in the area. 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 #11 through #16 containing the analytical results from this sampling event were received by Parsons from January 7 through January 29, 2004. Data validation was conducted and submittal to AFCEE is pending. 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).
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 consistently 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 samples from seven wells during the December 2003 sampling event and was present in the analysis method blanks as well.
Toluene was detected in the December 2003 sampling event at concentrations ranging from 0.061 �g/L to 8.5 �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 December 2003 sampling events, and subsequently toluene was detected at decreased concentrations and frequency.
Upon receipt of the preliminary on-post data from the December 2003 groundwater sampling event at CSSA, a discrepancy was noted for two samples collected on December 12, 2003. When the results were entered into the historical data tables, it was apparent that the results for sample CS‑MW8‑CC matched the historical results for sample CS‑MW10‑LGR indicating that the samples may have been switched. The laboratory was contacted to investigate a possible mislabeling or reporting error. However, the laboratory sample labels matched the labels applied by Parsons, and the lab confirmed that all data were reported correctly. Confirmation samples were then collected to confirm whether samples were mislabeled during collection. Samples from both wells in question (CS‑MW8‑CC and CS‑MW10‑LGR) were recollected on January 21, 2004. Results from the confirmation sampling matched the previous historical results for each well, proving that the two samples collected on December 12, 2003, had been switched during the initial sampling event. The original December 2003 data for these samples has been rejected (flagged �R�); data from the resampling in January 2003 is used in this report.
MCLs were exceeded in wells CS‑MW16‑LGR (formerly well CS‑16), CS‑MW1‑LGR, and CS‑D in the December 2003 event. The detected concentrations are summarized as follows:
| CS‑D � Concentrations of PCE (230 �g/L), TCE (290 �g/L), and cis-1,2‑DCE (270 �g/L) all exceeded the applicable MCL. Also detected was trans‑1,2‑DCE (2.1 �g/L) above the reporting limit (RL); and chloroform (0.23 �g/L) and 1,1‑DCE (0.092 �g/L) which were below the RL. | |
| CS‑MW16‑LGR � Concentrations of PCE (14.0 �g/L) and TCE (13.0 �g/L) exceeded the applicable MCL. Also detected were cis‑1,2‑DCE at 10.0 �g/L and methylene chloride at 0.21 �g/L; cis-1,2‑DCE was above the RL, and methylene chloride was below the RL. | |
| CS‑MW16‑CC � This well had previous detections above the MCL. In December 2003, this well was not sampled due to road construction in the area. The electrical supply was disconnected from the high-capacity submersible pump so road construction crews could gain access to the area. | |
| CS‑MW1‑LGR � PCE and TCE concentrations were 10.0 �g/L and 26.0 �g/L and were above the applicable MCL. Also detected were cis‑1,2‑DCE at 16.0 �g/L, trans‑1,2‑DCE at 0.13 �g/L, chloroform at 0.10 �g/L, and methylene chloride at 0.30 �g/L. Trans‑1,2‑DCE, chloroform, and methylene chloride were below the RL, while cis-1,2‑DCE was above the RL. |
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. Newly installed well CS‑MW16‑CC is not included in these figures because not enough data were collected to depict a trend. Concentration trends from 1991 to the present for CS‑MW16‑LGR and CS-D are given in Figure 5-1, and in Figure 5-2 from 1998 through 2003 for CS‑MW16‑LGR, CS‑D, CS‑MW1‑LGR and CS‑MW2‑LGR. CS‑MW16-LGR concentrations from the December 2003 event increased slightly since September 2003. In December 2003 concentrations in well CS‑D were the maximum detected since monitoring began in 1991, and have been generally increasing over time. 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 December 2003 the concentrations in well CS‑MW2‑LGR remained constant, while concentrations in CS‑MW1‑LGR showed a slight decrease.
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 in Section 5.1.1.
Wells CS‑MWH‑LGR and CS‑I had detections of toluene, but no other VOCs were detected in these wells. Well CS‑MWG‑LGR had a detection of methylene chloride, but no other VOCs were detected.
Well CS‑2 had detections of PCE and TCE at concentrations of 0.75 �g/L and 0.071 �g/L, respectively. This is the third consecutive event with a PCE detection. All detections were below the RL.
Well CS‑4 had detections of PCE and TCE at concentrations of 0.70 �g/L and 0.43 �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 (0.11 �g/L) and cis-1,2‑DCE (0.27 �g/L). All detections were below the RL. Well CS-MW1‑CC had a detection of toluene, but no other VOCs were detected.
CS-MW2‑LGR had detections of three VOCs. PCE, TCE, and cis‑1,2-DCE were detected at concentrations of 1.1 �g/L, 0.84 �g/L, and 0.60 �g/L, respectively. All detections were below the RL. Well CS‑MW2‑CC was sampled for the third time this quarter. The well had one VOC detection of toluene, but no other VOCs were detected.
Well CS‑MW3‑LGR continued to have no detections this quarter. CS‑MW4‑LGR had detections of TCE at a concentration of 0.054 �g/L and cis-1,2-DCE at a concentration of 0.15 �g/L, both 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 2.3 �g/L, cis-1,2-DCE was detected at 2.2 �g/L, and trans-1,2-DCE was detected at 0.048 �g/L (below the RL).
In December 2003, well CS‑MW6‑CC had no VOC detections. Well CS‑MW6‑LGR and CS‑MW6‑BS had detections of toluene, but no other VOCs were detected.
Well CS‑MW7‑LGR had two VOC detections, PCE at a concentration of 0.074 �g/L and TCE at a concentration of 0.038 �g/L, below the applicable RLs. Well CS‑MW7‑CC had a VOC detection of toluene, but no other VOCs were detected.
Well CS-MW8-LGR had a detection of toluene, but no other VOCs were detected. 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 (0.18 �g/L, below the RL). Well CS‑MW9-BS had a detection of toluene, but no other VOCs were detected. Well CS‑MW9‑CC had no VOC detections.
CS‑MW10‑LGR had detections of PCE and TCE at concentrations of 2.6 �g/L and 0.48 �g/L, respectively. PCE was above the RL and below the MCL while the TCE was below the RL. Well CS-MW10-CC had a detection of toluene, but no other VOCs were detected.
Well CS‑MW11A‑LGR was sampled for the third time in December 2003. Well CS‑MW11A‑LGR reported a detection of PCE (0.17 �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.
No VOCs were detected in CS‑MW12‑LGR. CS‑MW12‑BS had a detection of naphthalene at a concentration of 0.29 �g/L, below the RL. CS‑MW12‑CC had a detection of vinyl chloride at a concentration of 0.14 �g/L, below the RL. PCE was detected in well CS‑MW17‑LGR at a concentration of 0.17 �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 (0.36 �g/L) below the RL.
In summary, wells CS‑2, CS‑4, CS‑MW1‑BS, CS‑MW2‑LGR, CS‑MW4‑LGR, CS‑MW5‑LGR, CS‑MW7‑LGR, CS‑MW8‑CC, CS‑MW9‑LGR, CS‑MW10‑LGR, CS‑MW11A‑LGR, CS‑MW12‑BS, CS‑MW12‑CC, CS‑MW17‑LGR, CS‑MW18‑LGR and CS‑MW19‑LGR had detections of analytes below the MCL. Wells CS‑I, CS‑MWG‑LGR, CS‑MWH‑LGR, CS‑MW1‑CC, CS‑MW2‑CC, CS‑MW3‑LGR, CS‑MW6‑LGR, CS‑MW6‑BS, CS‑MW6‑CC, CS‑MW7‑CC, CS‑MW8‑LGR, CS‑MW9‑BS, CS‑MW9‑CC, CS‑MW10‑CC, CS‑MW12‑LGR, and CS‑MW12‑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 December 2003 were CS‑1, CS‑9, CS‑10, and CS‑11. All contaminant concentrations detected in these wells were below MCLs.
CS‑1 had detections of PCE, TCE, chloroform, and toluene at concentrations of 0.10 �g/L, 0.56 �g/L, 0.062 �g/L and 0.091 �g/L, respectively. All concentrations were below the RL. PCE, TCE, and chloroform concentrations remained constant with sporadic detections of toluene. December 2003 was the seventh consecutive detection of PCE (all F‑flagged) and the 18th consecutive detection of TCE (all F‑flagged).
Well CS‑9 had a detection of toluene at a concentration of 0.10 �g/L, below the RL.
Well CS‑10 had detections of toluene and chloroform at concentrations of 0.089 �g/L and 0.11 �g/L; both were below the RL. Well CS‑11 (a former drinking water well) had detections of toluene and chloroform at concentrations of 0.098 �g/L and 0.11 �g/L, respectively. Both detections were below the RL.
All monitoring and drinking water wells were analyzed for the metals arsenic, cadmium, lead, barium, chromium, copper, nickel, zinc, and mercury in June 2003. 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 December 2003, and none had a metals result above the appropriate MCL, action level (AL), or secondary standard.