[Home] [Master Table of Contents]

[Report Table of Contents] [Next Section]

March 2003 On-Post Quarterly Groundwater Monitoring Report

Section 4 - March 2003 Analytical Results

Groundwater sampling was performed March 17-24, 2003. Twenty-nine 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-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-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. Three additional samples (CS-1-NP, CS-9-NP, and CS-10-NP) were collected from drinking water supply wells prior to purging the well to determine if purging affects sample concentrations. The well CS-I windmill malfunctioned and this well was not sampled during this event.

The analytical program for on-post monitoring wells includes the CSSA short-list for volatile organic compound (VOC) analysis. Samples from the drinking water supply wells (CS-1, CS-9, and CS-10) and newly installed wells (CS-MW1-BS and CS-MW1-CC) were analyzed for the full list of VOCs, as well as nine metals. Three additional samples (CS-1-NP, CS-9-NP, and CS-10-NP) were collected from drinking water supply wells without purging the wells and analyzed for the short list of VOCs. Anions and cations were also analyzed for newly installed wells CS-MW1-BS and CS-MW1-CC. The metals analyzed include arsenic, cadmium, lead, barium, chromium, copper, nickel, zinc, and mercury. The on-post monitoring wells were analyzed for the reduced number (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, tetrachloroethene (PCE), trichloroethene (TCE), toluene, and vinyl chloride.

The Parsons data package ID numbers TO42 #77, #79, #80, and #81 contain the analytical results for this sampling event. The data packages were received by Parsons from April 11-25, 2003 and subsequently validated and submitted to AFCEE on May 12, 2003. AFCEE approval of the packages was received May 23, 2003. All detected concentrations of metals and VOCs are presented in Table 4-1. Full analytical results are presented in Appendix B. Cumulative VOC and metals data from this round and all previous sampling events can be found in Tables 6 and 7, respectively, of the Introduction to the Quarterly Groundwater Monitoring Program (Parsons, 2001) (Volume 5, Groundwater).

4.1 - Volatile Organic Compound Results

4.1.1   Toluene and Methylene Chloride Detections

Methylene chloride has been reported in samples from on- and off-post wells since 1992. However, each time methylene chloride has been detected in a sample, it has also been consistently present in the analysis method blank, indicating the likelihood that this analyte was introduced as a laboratory contaminant and is 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.

In addition, toluene was detected in almost every well during the March 2003 sampling event. Toluene concentrations ranged from 0.077 micrograms per liter (�g/L) to 9.9 �g/L. These levels are below the applicable maximum contaminant level (MCL) for toluene in drinking water (1,000 parts per billion [ppb]). These were the first toluene detections for most of these on-post samples and a possible source of this contamination was researched. Due to the sporadic low-level detections, a source associated with the sampling or analysis methodology was suspected. A sample of the adhesive tape used to secure the sample labels to the sample bottles was submitted for analysis. The resulting water was found to contain over 100,000 �g/L toluene. Therefore, it is suspected that the low-level concentrations detected in the March 2003 groundwater samples were introduced by volatilization of toluene on the tape and adsorption into the samples during transit from the field to the laboratory. The type of tape to be used for future sampling will be changed to a contaminant-free tape. The detection of toluene in future sampling events, if any, will further evaluate whether the March 2003 toluene detections were affected by the sampling method.

4.1.2   MCL Exceedances in Monitoring Wells

MCLs were exceeded in wells CS-MW16-LGR (formerly well CS-16), CS-MW1-LGR, and CS-D in the March 2003 event. The detected concentrations are summarized as follows:

The concentration trends over time for these three wells, and CS-MW2-LGR, for the contaminants of concern (COCs) for which MCLs were exceeded are shown in Figure 4-1, Figure 4-2, Figure 4-3, Figure 4-4, Figure 4-5, and Figure 4-6. These concentrations trends are given from 1991 to the present for CS-MW16-LGR and CS-D, and from 1998 through the present for CS-MW1-LGR and CS-MW2-LGR. CS-MW16-LGR concentrations from the March event decreased slightly since December 2002 but are below concentrations detected in 1998. In March 2003 concentrations in well CS-D were the maximum detected since monitoring began in 1991. The concentrations have been generally increasing over time with the exception of the March 2002 event, when concentrations declined. 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 2003 the concentrations in well CS-MW2-LGR remained constant while concentrations in CS-MW1-LGR decreased. Screening data from Well CS-D (December 2001) are included on the figures for comparison of concentration trends over time.

4.1.3   Detections below the MCL in Monitoring Wells

Additional wells had detections during March 2003 of COCs that were below the applicable MCLs. These wells are monitoring wells installed as part of the ongoing groundwater investigation.

CS-MW2-LGR had detections of five VOCs. PCE, TCE, cis-1,2-DCE, toluene, and vinyl chloride concentrations were detected at concentrations of 2.2 �g/L, 2.1 �g/L, 1.4 �g/L, 5.7 �g/L, and 0.032 �g/L respectively. PCE, TCE, cis-1,2-DCE, and toluene were above the RL and below the MCL and vinyl chloride was below the RL. Previous CS-MW2-LGR detections have been above the MCL for PCE and TCE.

CS-MW5-LGR had five VOC analytes detected. PCE was detected at a concentration of 1.7 �g/L, TCE was detected at 2.5 �g/L and cis-1,2-DCE was detected at 2.8 �g/L, all below applicable MCLs. Additional analytes detected below the RL were toluene at 0.077 �g/L and trans-1,2-DCE at 0.080 �g/L. Concentrations in March 2003 are an increase for these COCs since previous sampling.

CS-MW10-LGR had five VOC detections of PCE, TCE, 1,1-DCE, toluene, and chloroform at concentrations of 2.1 �g/L, 0.51 �g/L, 0.052 �g/L, 2.6 �g/L, and 0.13 �g/L, respectively. PCE and toluene were above the RL and below the MCL while the TCE, chloroform, and 1,1-DCE concentrations were above the MDL and below the RL. The PCE, TCE, and chloroform results are consistent with concentrations detected since the well was initially sampled in December 2001. This is the first detection of 1,1-DCE and toluene is this well. Well CS-MW10-CC had two VOC detections. Naphthalene was detected below the RL at a concentration of 0.23 �g/L and toluene was detected above the RL at 2.1 �g/L. Historically CS-MW10-CC has had one previous detection of PCE in September 2002 and one previous detection of methylene chloride in March 2002.

CS-MW4-LGR had six VOC analytes detected. PCE was detected at a concentration of 0.12 �g/L, which is below the RL. TCE was detected at 0.098 �g/L, cis-1,2-DCE was detected at 0.22 �g/L, and vinyl chloride was detected at 0.051 μg/L, all below the RL. Also detected were naphthalene at 0.86 �g/L and toluene at 2.5 �g/L. This is the second consecutive detection of PCE and TCE since CS-MW4-LGR was initially sampled in June 2001. Well CS-MW4-LGR has a history of cis-1,2-DCE detections above the MDL and below the RL.

Well CS-MWH-LGR (formerly known as CS-H) was upgraded with a high capacity submersible pump in December 2002. In March 2003, well CS-MWH-LGR had three VOC detections, bromoform at a concentration of 0.10 �g/L, dibromochloromethane at 0.030 �g/L, and toluene with a concentration of 4.0 �g/L. The toluene concentration was above the RL and bromoform and dibromochloromethane were above the MDL but below the RL.

Wells CS-MW1-BS and CS-MW1-CC were sampled for the first time following their installation. CS-MW1-BS had seven VOC detections: PCE (0.19 �g/L), TCE (0.24 �g/L), benzene (0.045 �g/L), cis-1,2-DCE (1.3 �g/L), ethylbenzene (0.07 �g/L), toluene (9.9 �g/L) and 1,2,4-trimethlybenzene (0.059 �g/L). All detections were below the MCL and benzene, ethylbenzene, PCE, TCE, and 1,2,4-trimethylbenzene were below the RL. Well CS-MW1-CC had detections of styrene (0.043 �g/L), toluene (0.54 �g/L), and 1,2,4-trimethylbenzene (0.063 �g/L), below the RL.

In March 2003, well CS-MW6-LGR had two VOC detections. Naphthalene was detected, below the RL, at a concentration of 0.25 �g/L and toluene was detected, above the RL, at a concentration of 2.2 �g/L. These two analytes have no historical detections in this well. PCE, TCE, and cis-1,2-DCE, were originally reported in CS-MW6-LGR in June 2001 in its first sampling event; however, these analytes were not detected in March 2003. Well CS-MW6-BS had three VOC detections. Cis-1,2-DCE (0.14 �g/L) and naphthalene (0.23 �g/L) were detected above the MDL and below the RL. Toluene was detected above the RL and below the MCL at a concentration of 1.9 �g/L. This is the first detection of cis-1,2-DCE and naphthalene in well CS-MW6-BS. Well CS-MW6-CC had detections of TCE (0.09 �g/L) and toluene (2.4 �g/L). This is the first detection of TCE since the well was first installed in June 2001.

Well CS-MW7-LGR had detections of naphthalene and toluene at concentrations of 0.32 �g/L and 2.5 �g/L, respectively. This is the first time naphthalene and toluene have been analyzed and/or detected in this well. Only toluene (2.8 �g/L) was detected in CS-MW7-CC.

Well CS-MW8-LGR had a VOC concentration of PCE at 0.67 �g/L, TCE at 0.032 �g/L, cis-1,2-DCE at 0.21 �g/L, and toluene at 2.9 �g/L. These concentrations were above the MDL and below the RL with the exception of toluene, which was above the RL and below the MCL. Concentrations of PCE have remained stable, and below the RL, since the well was first sampled in June 2001. TCE was initially detected in June 2001 and not reported again until the March 2002 event. The March 2003 event is the first detections for toluene and cis-1,2-DCE in this well. Only toluene (3.5 �g/L) was detected in CS-MW8-CC.

Well CS-MW9-LGR had three VOC detections in March 2003, TCE (0.26 �g/L), naphthalene (0.49 �g/L), and toluene (0.26 �g/L) with TCE and naphthalene below the RL. These are the first TCE, toluene, and naphthalene detections in well CS-MW9-LGR since it was installed in June 2001. Historically PCE and methylene chloride have been sporadically detected in this well. CS-MW9-BS had a vinyl chloride detection above the MDL and below the RL at a concentration of 0.059 �g/L. This is the second consecutive detection of vinyl chloride in this well since it was first sampled in June 2001. Toluene was also detected at a concentration of 0.60 �g/L in this sampling event (below the RL). Well CS-MW9-CC had detections of cis-1,2-DCE and toluene at concentrations of 0.40 �g/L and 0.20 �g/L, respectively (below the RL). This is the first detection of cis-1,2-DCE. Toluene was detected during the first sampling event in June 2001. PCE and TCE have never been detected in CS-MW9-CC.

Only toluene (1.4 �g/L) was detected in CS-MW12-LGR. CS-MW12-BS had four VOC detections: 1,1-DCE, naphthalene, toluene, and vinyl chloride at concentrations of 0.032 �g/L, 0.31 �g/L, 2.8 �g/L, and 0.096 �g/L. These concentrations were above the MDL and below the RL for all analytes except toluene, which was above the RL. CS-MW12-CC had a VOC detection of toluene at a concentration of 3.3 �g/L. This concentration was above the RL and below the MCL. Toluene was also reported last quarter along with benzene. This was the second sampling event for the CS-MW12 cluster. Toluene was the only analyte detected in the first sampling event.

Well CS-2 had toluene and chloroform detections of 8.7 �g/L and 0.12 �g/L. The chloroform concentration was above the MDL and below the RL. Toluene was above the RL and below the MCL. This is the first detection of toluene in this well and the second consecutive detection of chloroform.

Well CS-MW17-LGR was installed in August 2002. This is the third quarterly sampling event for this well. PCE was detected at a concentration of 0.23 �g/L and methylene chloride was detected at a concentration of 0.25 �g/L, both below the RL. Toluene was reported above the RL at a concentration of 3.6 �g/L. All reported analytes have been previously reported in this well.

Well CS-MW18-LGR reported a detection of TCE (0.097 �g/L, below the RL) for the first time since the well was installed in September 2002. Toluene was also detected at a concentration of 3.6 �g/L, above the RL and below the MCL.

Well CS-MW19-LGR was installed in August 2002. This is the third quarterly sampling event for this well. Detections of PCE (0.21 �g/L), trans-1,2-DCE (0.04 �g/L), methylene chloride (2.6 �g/L), 1,1-DCE (0.032 �g/L), toluene (4.4 �g/L), and vinyl chloride (0.053 �g/L) were reported in this well. PCE, 1,1-DCE, and vinyl chloride were above the MDL and below the RL while methylene chloride and toluene were above the RL and below the MCL. All analytes have been previously detected in this well with the exception of 1,1-DCE and vinyl chloride which were detected for the first time in CS-MW19-LGR.

Well CS-MW3-LGR is the only monitoring well that reported no VOC analytes detected above either the MDL or RL.

4.1.4   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 that were sampled in March 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, methylene chloride, and toluene at concentrations of 0.08 �g/L, 0.15 �g/L, 0.31 �g/L, and 3.7 �g/L, respectively. All concentrations were above the MDL and below the RL with the exception of toluene, which was above the RL. All concentrations have remained constant with sporadic detections of toluene and methylene chloride.

Well CS-10 had PCE, chloroform, methylene chloride, and toluene at concentrations of 0.09 �g/L, 0.41 �g/L, 0.29 �g/L, and 4.6 �g/L, respectively. PCE and methylene chloride were above the MDL and below the RL, while toluene and chloroform were above the RL.

Well CS-9 had detections of PCE, methylene chloride, chloromethane, and toluene at concentrations of 0.055 �g/L, 0.36 �g/L, 0.1 �g/L, and 2.5 �g/L, respectively. PCE and methylene chloride were above the MDL and below the RL, while toluene was detected above the RL. This is the first detection of PCE in well CS-9 since March 2001. Well CS-11 (a former drinking water well) had a concentration of toluene at 2.3 �g/L.

Samples were collected from drinking water wells CS-1, CS-9, and CS-10 under non-purged conditions. These non-purged samples were collected to analyze results from water as it is used, directly from the drinking water well, and to determine if purging affects sampling concentrations. Sample CS-1-NP reported detections of bromochloromethane (1.4 �g/L), bromodichloromethane (2.6 �g/L), bromoform (3.4 �g/L), chloroform (1.8 �g/L), chloromethane (0.11 �g/L), 2-chlorotoluene (0.069 �g/L), 4-chlorotoluene (0.048 �g/L), dibromochloromethane (3.7 �g/L), dibromomethane (0.19 �g/L), methylene chloride (1.2 �g/L) and toluene (0.32 �g/L) of which bromochloromethane, chloromethane, 2-chlorotoluene, 4-chlorotoluene, dibromomethane, methylene chloride, and toluene were below the RL. Samples CS-9-NP and CS-10-NP reported detections of methylene chloride (0.33 �g/L and 0.31 �g/L, respectively, both below the RL) and toluene (3.0 �g/L and 1.6 �g/L, respectively).

The results from non-purged samples in CS-1-NP indicated higher concentrations of the analytes bromochloromethane, bromodichloromethane, bromoform, chloroform, chloromethane, 2-chlorotoluene, 4-chlorotoluene, dibromochloromethane, dibromomethane, and methylene chloride. Results for non-purged samples CS-9-NP and CS-10-NP indicated detections at the same order of magnitude as the purged samples. Additional non-purged samples should be collected to further evaluate the presence of COCs in non-purged drinking water.

4.2 - Metals Analyses

Wells CS-1, CS-9, CS-10, CS-MWH-LGR, CS-MW1-BS and CS-MW1-CC were analyzed for the metals barium, calcium, chromium, copper, iron, magnesium, manganese, nickel, potassium, sodium, zinc, arsenic, cadmium, and lead. All CSSA livestock and monitoring wells are analyzed for these metals once annually and in the first sampling event following well installation or upgrade. The next annual sampling event for metals in all CSSA wells will be June 2003.

Of the wells sampled for metals during March 2003, no on-post monitoring or drinking water wells had a metals results above the appropriate MCL, action level (AL), or secondary standard.

[Next Section]