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)).

A geophysical survey, surface, and subsurface sampling  were conducted to determine if there is evidence of surficial contamination or buried waste at the site.  In addition, samples were collected from the backfill around an active sanitary sewer line which was suspected to have been backfilled with lead contaminated sand.

Yes.  The geophysical investigation revealed three subsurface geophysical anomalies, none of which were related to waste or closure considerations.  Surficial samples along with samples of the backfill around the sanitary sewer line indicated no elevated levels of site COCs above RRS1 limits.  However, and zinc was detected in two samples (9.5 feet bgs) above RRS1 limits.  Because the zinc concentrations that exceed RRS1 are less than the Texas-specific median background concentration, are not significantly above background and appear to be unrelated to any historical waste handling activities that may have occurrred at the surface, and because no other COCs were detected above RRS1 closure limits, RRS1 closure is warranted.

Closure under RRS1.

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 second revision to the Evaluation of Background Metals Concentrations in Soils and Bedrock at CSSA (Parsons, February 2002).

No.  Zinc was detected in two samples (9.5 feet bgs) above CSSA background levels.

Although RRS1 levels were exceeded for zinc in two samples, further action at SWMU B-31 is not recommended.  See discussion in Section 3.3 supporting this argument.

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

Surface and subsurface samples were collected at the site and analyzed for contaminants of potential concern including metals, VOCs and explosives.  

See above.

See above

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 SWMU B-31.  Shallow groundwater was not encountered during drilling at the site. 

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 soils is 7.87.

Yes.

NA

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

The moisture content of each sample was analyzed.  Moisture content values are provided in Table B31-1 and Appendix A.

Yes.

NA

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

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

No marshes, creeks, wetland areas, or ditches are present at the site.  Direction of runoff flow has been evaluated in Section 1.2.1.

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.

Yes

NA

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.

Yes.

NA

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

Information regarding the type of site was obtained from the Environmental Assessment (ES 1992) and from field activities. 

Yes

NA

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 design of the disposal site is provided in Section 1.1.2.1.

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 1.1.2.1.  This information is from the Environmental Assessment, records review, interviews, aerial photo review, and visual observations.

To the extent possible with the 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 1.1.2.1.

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.

NA

NA

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

Characterize the vertical and horizontal extent of groundwater contamination.

Not included in this phase of the RFI at SWMU B-31.  Shallow groundwater was not encountered during drilling at the site. 

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 and borings were advanced in areas thought to contain contamination.

Although CSSA background levels were exceeded for zinc in two samples, further action at SWMU B-31 is not recommended.  See discussion in Section 3.3 supporting this argument.

NA

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

See “Characterization of Environmental Setting – Soils” above.

NA

NA

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

NA

NA

NA

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

NA

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.

A soil boring investigation was conducted and samples were analyzed for VOCs, explosives, and metals.

Yes.

NA

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

“M” flagged data are also considered usable. The matrix interference is minimal and does not significantly affect the sample results.

NA

All “R” flagged data are considered unusable. Non-compliance of the relative percent difference (RPD) of the field duplicate collected on the same day lead to “R” flagged data for one metal.  There were five sets of field duplicates collected on the same day at different sites. The non-compliant RPD was a field duplicate collected for surface soil samples. This non-compliance resulted in flagging one metal for two soil boring samples. In addition, two out of the five sets of field duplicates collected were for soil boring samples. Both these sets of quality control (QC) data were within QC criteria.  

Yes

As the field duplicates for the soil boring samples were compliant, it is evident that the sample collection procedures were not compromised. Since the non-compliant field duplicate was a surface soil sample and the rejected metal was from a soil boring sample, the data are considered usable for characterization and closure purposes.

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.

SWMU B-31 is located in the southwestern portion of CSSA, and there are no creeks or ponds in the immediate vicinity. Therefore, surface water and sediments were not sampled as part of the SWMU B-31 investigation.

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 identifies private groundwater users within 0.25 miles and public water suppliers within 0.5 miles of CSSA.

Yes

NA