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 for each formation of the Middle Trinity Aquifer (3.5.3).

Potentiometric surface maps were prepared based on water levels measured in each of CSSA�s wells screened in three formations on March 5, 2004. 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. Ongoing pumping in the CSSA area likely affects the natural groundwater flow direction.

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 (2.1.9).

Potentiometric maps were created using March 5, 2004 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.

Define formation(s) in the Middle Trinity Aquifer are impacted by the VOC contaminants (2.1.3).

Quarterly groundwater monitoring, as well as monitoring wells equipped with Westbay� - multi-part samples provide information on Middle Trinity Aquifer impacts.

Yes.

Continue sampling.

Identify any temporal changes in hydraulic gradients due to seasonal influences (2.1.5).

Downloaded data from continuous-reading transducer at CS-MW16-LGR, CS-MW4-LGR, CS-MW9-LGR, CS-MW9-BS, and continuous-reading weather stations adjacent to CS-MW16-LGR and AOC-65. Graphed water levels at these wells against precipitation and season (date).

Yes.

Continue collection of transducer data and possibly install transducers in other cluster wells.

Contamination Characterization (Ground Water Contamination)

Characterize the horizontal and vertical extent of any immiscible or dissolved plume(s) originating from the Facility (3.1.2).

Samples for laboratory analysis were collected from 38 of 41 CSSA wells. Well CS-3 was not sampled because it is located adjacent to well CS-2 and CS-4, which were sampled. No sample was obtained from CS-MW11B-LGR because the water table was below the pump. Well CS-MW16-CC was not sampled due to construction in the area.

The horizontal and vertical extent of groundwater contamination is continuously monitored.

Continue groundwater monitoring and construct additional wells as necessary.

Determine the horizontal and vertical concentration profiles of all constituents of concern (COCs) in the groundwater that are measured by USEPA-approved procedures (3.1.2). COCs 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-4, CS-9, CS-10, CS-11, CS-MW16-LGR, CS-D, CS-MWG-LGR, CS-MWH-LGR, CS-I, 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-MW17-LGR, CS-MW18-LGR, and CS-MW19-LGR. Samples were analyzed for the selected VOCs using USEPA method SW8260B. Drinking water wells were analyzed for 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 RLs were below MCLs, as listed below:

Yes.

Continue sampling.

Analyte RL (ug/L) MCL (ug/L)
Chloroform 0.4 100
Chloromethane 1.3 --
Dibromochloromethane 0.5 100
1,1-DCE 1.2 7
cis-1,2-DCE 1.2 70
trans-1,2-DCE 0.6 100
Methylene Chloride 2 5
PCE 1.4 5
TCE 1.0 5

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

Barium 5 2000
Chromium 10 100
Copper 10 1300
Nickel 10 100
Zinc 10 11000
Arsenic 5 50
Cadmium 1 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 CSSA QAPP and approved variances. Parsons chemists verified all data, and AFCEE approval was obtained.

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

Previously, an MDL study for arsenic, cadmium, and lead was 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.

Remediation

Determine goals and create cost-effective and technologically appropriate methods for remediation (2.2.1).

Continued data collection will provide analytical results for accomplishing this objective.

Ongoing.

Continue sampling and evaluation, including quarterly groundwater monitoring teleconferences to address remediation.

Determine placement of new wells for monitoring (2.3.1, 3.6)

Sampling frequency and sample locations to be monitored (including any new wells) will be based on trend data from monitoring event(s) (3.1.5).

Ongoing.

Continue quarterly groundwater teleconferences to discuss sampling frequency and placement of new monitor wells.

Project schedule/ Reporting

Produce a quarterly monitoring project schedule as a road map for sampling, analysis, validation, verification, reviews, and reports.

Prepare schedules and sampling guidelines prior to each quarterly sampling event.

Yes.

Continue sampling schedule preparation each quarter.