An average decrease in water levels of 70.97 feet occurred between December 2001 and March 2002.  This average decrease is calculated from wells screened in separate formations and open boreholes.  CSSA had 2.25 inches of rainfall between December 22, 2001 and March 22, 2002.  Rainfall events were spread throughout the 3-month period with the majority of rainfall occurring in January and February 2002.  No rainfall event exceeded 1 inch per 24-hour period. 

The groundwater elevation map for March 2002 indicates a variety of groundwater flow directions and large fluctuations in the potentiometric gradient.  Groundwater extraction from both on- and off-post drinking water supply wells, varying rates of recharge from rain events, and differences in well completions all contribute to the complexity of the potentiometric surface at CSSA. 

The potentiometric surface map for the vicinity of Building 90, separated by formations, indicates a groundwater flow to the south-southeast in the Lower Glen Rose in March 2002 which is a slight deviation from December 2001 (south-southwest).  The flow direction in the Cow Creek Formation was observed to be toward the north in December 2001 and has reversed directions, to the south, in the March 2002 event. 

MCLs for PCE and TCE were exceeded in Well CS-16 during the March 2002 monitoring event.  The concentrations of these compounds in Well CS-16 were 28.0 mg/L and 26.0 mg/L, respectively.  Well CS-16 exhibits variation in concentrations (i.e. 21 �g/L to 509 �g/L) with a general decreasing trend observed over the last two years. 

Well CS-D data for the compounds TCE, PCE, and cis-1,2-DCE exceeded the MCL with concentrations of 100 mg/L, 160 mg/L, and 150 mg/L, respectively.  PCE and TCE  concentrations have declined slightly over the last nine months.

On-post drinking water wells CS-1, CS-9, and CS-10 did not have any VOC concentrations that exceeded the RL and/or MCL. 

Well CS-I, a livestock supply well, exhibited a lead concentration of 87.0 mg/L, which exceeds the AL for lead of 15.0 mg/L.  No drinking water wells or other monitoring wells contained metals concentrations above the appropriate MCL or AL. 

Wells CS-MW1-LGR and CS-MW2-LGR continue to exhibit concentrations above the MCLs for PCE and TCE.  In March 2002, CS-MW1-LGR detected PCE at 19.0 �g/L and TCE at 30.0 �g/L, and well CS-MW2-LGR had concentrations for PCE of 9.1 �g/L and TCE of 7.1 �g/L. 

Figure 5-1, Figure 5-2 and Figure 5-3 are included for evaluation of the concentrations of PCE, TCE, and cis-1,2-DCE over time in wells in which these compounds have exceeded the MCL (CS-D, CS-16, CS-MW1-LGR, and CS-MW2-LGR).  Concentrations have varied greatly over time with generally increasing trends over the last year of groundwater monitoring.

Field Sampling

Conduct field sampling in accordance with procedures defined in the project work plan, SAP, QAPP, and HSP.

All sampling was conducted in accordance with the procedures described in the project plans. 

Yes.

NA

Characterization of Environmental Setting (Hydrogeology)

Prepare water-level contour and/or potentiometric maps (B.3.A.1(e)(1))

Potentiometric surface map was prepared based on water levels measured in each of CSSA�s wells on March 11, 2002.  In addition, an average water level for a Fair Oaks Ranch Utilities well (F0-20, northwest of CSSA) was also obtained. 

To the extent possible with data available.  Due to the limited data available and the fact that wells are completed across multiple water-bearing units, potentiometric maps should only be used for regional water flow direction, not local.  Furthermore, pumping in the area likely affects the natural groundwater flow direction. 

As formation-specific water level information becomes available, prepare water level map for each unit.  At present, water levels in all CSSA wells should continue to be measured and all data should be mapped together due to the lack of data for any one zone.  Comparisons between LGR and CC screened water levels in the vicinity of Building 90 is being performed currently.  As additional wells are installed screened in distinct formations, future evaluations will eliminate reliance on wells screened across multiple formations. 

Describe the flow system, including the vertical and horizontal components of flow (B.3.A.1(e)(3)).

Potentiometric maps were created using March 11, 2002 water level data, and horizontal flow direction was tentatively identified.  Insufficient data are currently available to determine vertical component of flow.

As described above, due to the lack of aquifer-specific water level information, potentiometric surface maps should only be used as an estimate of regional flow direction.

Same as above.

Identify any temporal changes in hydraulic gradients due to seasonal influences (B.3.A.1(e)(4)).

Downloaded data from continuous-reading transducer at CS-16, CS-MW4-LGR, CS-MW9-LGR, CS-MW9-BS, CS-MW9-CC, and continuous-reading weather station adjacent to CS-16.  Graphed water levels at these wells against precipitation.

Information provided by CS-16 transducer-weather station is a start to identifying temporal changes.  Very rapid changes in water levels have been observed at CS-16 after precipitation.  However, CS-16 is completed in three units; therefore, the unit-specific effect is not known.

Install transducers in several cluster wells, after installation is complete, to determine effects of precipitation on each unit.  Wells where rapid effects are noticed, such as at wells CS-D and CS-MW1-LGR (both completed in the Glen Rose only), should also be considered for transducer installation.

Contamination Characterization (Ground Water Contamination)

Characterize the horizontal and vertical extent of any immiscible or dissolved plume(s) originating from the Facility ((B.3.C.1(a))

Samples for laboratory analysis were collected from all of the CSSA wells, except wells 3 and 4, which are located adjacent to well 2.

There are currently insufficient data to determine the horizontal or vertical extent of groundwater contamination. 

As described above, additional wells are currently being installed which will help in determining horizontal and vertical extent of contamination.

Determine the horizontal and vertical concentration profiles of all constituents of potential concern (COPCs) in the groundwater that are measured by EPA-approved procedures (B.3.C.1(d)).  COPCs are those chemicals that have been detected in groundwater in the past and their daughter (breakdown) products.

Groundwater samples were collected from wells: CS-1, CS-2, CS-9, CS-10, CS-11, CS-16, CS-D, CS-G, CS-H, CS-I, CS-MW1-LGR, 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.  Samples were analyzed for the selected VOCs using EPA method SW8260B, arsenic, cadmium, and  lead by SW6020, mercury by SW7470, and barium, chromium, copper, nickel, and zinc by SW6010B.  Analyses were conducted in accordance with the AFCEE QAPP and approved variances.  All reporting limits were below MCLs, as listed below:

Yes.

NA.

Analyte               RL (ug/L)        MCL (ug/L)
Bromodichloromethane 0.8                     100
Chloroform                   0.4                     100
Dibromochloromethane 0.5                     100
1,1-DCE                       1.2                       7
cis-1,2-DCE                  1.2                      70
trans-1,2-DCE              0.6                     100
Dichloromethane           2                        5
PCE                              1.4                       5
TCE                              1.0                       5
Vinyl Chloride               1.1                       2

Analyte               RL (ug/L)        MCL (ug/L)

Barium                          5                        2000
Chromium                   10                        100
Copper                        10                        1300
Nickel                         10                        100
Zinc                            10                       11000
Arsenic                        20                        50
Cadmium                     2                          3
Lead                            2                          15
Mercury                      1                          2

Contamination Characterization (Ground Water Contamination)
(Continued)

Meet AFCEE QAPP quality assurance requirements.

Samples were analyzed in accordance with the AFCEE QAPP and approved variances. All data were verified by a chemist. 

Yes.

NA

All data flagged with a �U,� �J,� and �F� are usable for characterizing contamination.  All �R� flagged data are considered unusable.  

Yes.

NA 

The method detection limit study for arsenic, cadmium, and lead were not performed within a year of the analyses, as required by the AFCEE QAPP.

The laboratory performed new MDL studies in February 2001 for these metals and the new MDL values were found to be almost identical to the previous MDLs and all met the associated AFCEE QAPP requirements.  MDLs for these three metals are well below MCLs.  In addition, the laboratory performed daily calibrations and RL verifications for these metals, both of which demonstrate the laboratory�s ability to detect and quantitate these metals at RL levels.  These daily analyses also indicate that concentrations above the laboratory RL for these compounds were not affected by the expired MDL study.

Use results for groundwater characterization purposes.