Objective 1:  Meet TNRCC Requirements for Site Closure

Attainment of Risk Reduction Standard Number 1: Closure/Remediation to Background

Remove all hazardous and nonhazardous waste and waste residues and contaminated design and operating system components such as liners, leachate collection systems, and dikes from the unit or area of the unauthorized discharge. For remediation of media that have become contaminated by releases from a waste management unit or by other unauthorized discharge of hazardous or nonhazardous waste, the contaminated media must be removed or decontaminated to cleanup levels specified in this section (30 TAC 335.554(b) and (c)).

Field efforts conducted in 1958 and the 1995 EM geophysical survey and resultant field effort all verified that no mustard gas canisters or UXO were located at AOC 36.  AOC 36 was closed by TNRCC with regard to mustard gas canister contamination.  Metal debris detected during field investigation was disposed of.  Soil gas survey results indicated that chlorinated VOCs were present at AOC 36 related to well CS-16. 

Yes, confirmation surface soil sampling was conducted at locations designed to investigate the chlorinated VOCs detected in the soil gas survey results. 

Confirmation surface soil samples did not detect any VOCs at concentrations greater than RLs.  Therefore, AOC 36 should be granted closure. 

Determine compliance with RRS1 closure requirements by comparing to background as represented by results of analyses of samples taken from media that are unaffected by waste management or industrial activities. If the practical quantitation limit (PQL) is greater than background, then the PQL rather than background shall be used as the cleanup level provided that the person satisfactorily demonstrates to the executive director that lower levels of quantitation of a contaminant are not possible (30 TAC 335.554(d)).

Contaminant concentrations were compared to the RLs for the analytes, specifically:  1,1-DCE, cis-1,2-DCE, trans-1,2-DCE, PCE and TCE only. 

None of the surface soil samples collected exceeded AFCEE RLs; therefore, the site meets RRS1 closure criteria for VOCs.

RRS1 Closure

Attainment of cleanup levels shall be demonstrated by collection and analysis of samples from the media of concern (30 TAC 335.554(e)).

The COCs detected during the 1995 soil gas surveys, i.e.;  1,1-DCE, cis-1,2-DCE, trans-1,2-DCE, PCE, TCE and carbon tetrachloride determined the need for additional surface soil sampling.

Yes

RRS1 Closure

Objective 2:  Meet Requirements of 3008(h) Order for RFI

RFI Workplan Requirements

Field Sampling (Detailed listing of methods and procedures are provided in project plans which are incorporated by reference).

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

Facility Investigation

Characterization of Environmental Setting - Hydrogeology (B.3.A.1)

Evaluate hydrogeologic conditions at the site.

Not included in this phase of the RFI at AOC 36.  Subsurface sampling was not conducted at AOC 36.

Groundwater of the Trinity Aquifer is being addressed through the Groundwater Investigation.

NA

NA

Characterization of Environmental Setting- Soils (B.3.A.2)

Characterize soils in accordance with USCS soil classification system (B.3.A.2(a)).

Soil types at the site are based on the SCS Bexar County Soil Survey (USDA, 1991) and are described in Section 1.2.1. 

Yes

NA

Determine soil pH (B.3.A.2(e)).

The pH of each of the soil types evaluated as part of the background metals concentration study was determined through laboratory analysis.  According to those analyses, the pH of Krum Complex and Tarrant association soils is 7.87 and 8.08, respectively.

Yes.

NA

Determine moisture content (B.3.A.2(g)).

The moisture content of each sample was analyzed.  Moisture content values are provided in the laboratory packages..

Yes.

NA

Characterization of Environmental Setting – Surface Water and Sediment (B.3.A.3)

Characterize marshes, creeks, wetland areas, or ditches at the site.

The nearest surface water body is an ephemeral stream that traverses AOC 36 across the northwestern site corner and flows generally southwest across AOC 36. 

Yes

NA

Source Characterization (B.3.B)

Identify the source area (B.3.B.1).

A description of the source area is provided in Section 1.1.2.2.

Sampling at the site was biased toward areas most suspected of contamination, including the sample locations for detected VOCs during the soil gas surveys in 1995.  No contamination was found.

RRS1 Closure

Identify the location of the unit/disposal area (B.3.B.2(a)).

In 1999, points along the boundary of each site were surveyed with a Rockwell Plugger GPS unit (estimated accuracy of ±25 feet).  The measurement points were identified by the CSSA Environmental Coordinator.  The boundary of the site was reviewed during preparation of this report and adjusted, if necessary, based on observations made during the field investigation.

Yes.

NA

Identify the type of unit/disposal area (B.3.B.2(b)).

AOC was identified as a mustard gas canister disposal area in Army EOD reports stating the site was cleared in 1958.   An EM geophysical survey and excavation of all detected anomalies was conducted to verify any potential UXO.  No mustard gas canisters or UXO were detected.

Yes.  Excavation was conducted at the site to determine whether mustard gas canisters or UXO were present and soils were sifted to remove UXO.

RRS1 Closure

Identify design features (B.3.A.2(c)).

Information regarding design features was obtained during the Environmental Assessment (ES, 1992) and through visual observation during the field investigation.  All available information regarding the usage/design  of the disposal site is provided in Section 1.1.2.2.

Yes

NA

Identification of past and present operating practices, period of operation, age of unit/disposal area, and method used to close the unit/disposal area (B.3.B.2(d), (e), (f), and (h)).

All known information regarding these items is provided in Section 1.1.2.2.  This information is from the Environmental Assessment, records review, interviews, aerial photo review, and visual observations.

To the extent possible with data available.

NA

Determine general physical conditions of the site (B.3.B.2(g))

The general physical condition of the site was determined during the field investigation.  This information is presented in Section 2.1.

Yes.

NA

Identify waste characteristics, including type of waste placed in the unit, physical and chemical characteristics of the wastes, and migration and dispersal characteristics of the waste (B.3.B.3).

Records regarding historic waste disposal practices at CSSA are very limited.  All known information, derived from the Environmental Assessment, records review, interviews, and visual observations at the site is provided in Section 1.1.2.2 and Section 1.3.

Yes

NA

Contamination Characterization – Groundwater (B.3.C.1)

Characterize the vertical and horizontal extent of groundwater contamination.

Shallow groundwater was not encountered as subsurface investigation was not part of the investigation at AOC 36. 

Groundwater of the Trinity Aquifer is being addressed through the Groundwater Investigation.

NA

NA

Contamination Characterization – Soil (B.3.C.2)

Determine vertical and horizontal extent of contamination (B.3.C.2(a)).

Surface samples were collected in areas thought to contain contamination.

Yes, all samples reported concentrations less than the RLs.

RRS1 Closure

Describe contaminant and soil properties with the contaminant source area, including contaminant solubility, speciation, adsorption, leachability, exchange capacity, biodegradability, hydrolysis, photolysis, oxidation, and other factors that might affect contaminant migration and transformation (B.3.C.2(b)).

NA

NA

NA

Describe soil properties (B.3.C.2(c)).

See “Characterization of Environmental Setting – Soils” above and Section 1.2.1.

Yes

NA

Identify the direction of contaminant movement (B.3.C.2(d)).

No action taken

NA

NA

Extrapolate future contaminant movement (B.3.C.2(e)).

No action taken

NA

NA

Implement a soil boring investigation to determine the extent of soil contamination.  Soil gas monitoring will be performed during drilling of all borings.  Laboratory analysis of borings for contaminants of potential concern will be performed on soils at depths where either visual contamination is evident, or soil gas concentrations indicate contamination.  All boreholes shall be properly abandoned.

Not included in this phase of the RFI at AOC 36.   Further subsurface investigation was not indicated at AOC 36 as all confirmation surface soil samples reported concentrations of COCs less than the RLs.

Yes

RRS1 Closure

Prepare a map of all areas included in the investigation (B.3.C.2(i)).

Figures included in this report show all areas included in the investigation.

Yes

NA

All reporting limits should be below regulatory criteria.

RLs were approved by TNRCC on October 5, 1999.  RLs are considered RRS1 standards for all analytes except metals. 

Yes

NA

Perform all analyses in accordance with the AFCEE QAPP.

All analyses were performed in accordance with the AFCEE QAPP and approved variances. 

Yes

NA

All data flagged with “U,” “F,” “M,” and “J” are considered usable for site characterization purposes. 

Yes

NA

No data reported from confirmation surface soil samples at AOC 36 were flagged with an “R.”

NA

NA

Contaminant Characterization – Sediment and Surface Water (B.3.C.3)

Conduct a surface water and sediment investigation to characterize contamination resulting from releases at the facility.

AOC 36 is located in the central portion of CSSA.  The only surface water body at AOC 36 is an ephemeral creek traversing the northwest corner of AOC 36.  No surface water sampling was conducted.

Yes

NA

Potential Receptors (B.3.D).

Collect the information necessary to describe the human populations and environmental systems that are susceptible to contamination exposure from the facility.

Information regarding receptors is provided in the Risk Assessment Technical Approach document (Volume 1-6).  In addition, the Well Research Report identified private groundwater users within 0.25 miles and public water suppliers within 0.5 miles of CSSA.

Yes

NA