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Soil Pile Disposition Assessment
Section 4 - Corrective Action Objectives
Corrective action objectives endeavor to protect human health and the environment with goals specific to each environmental medium affected. Preliminary objectives are derived from risk evaluations and regulatory requirements. In general, the objective of corrective actions is to remove or remediate contamination to applicable regulatory criteria intended to safeguard human health and the environment.
The extent of contamination at the site is defined as those areas that exceed established risk-based criteria. Those criteria are extensive and are dependent on media, contaminant, and exposure pathways.
The basic objectives of investigative studies at SWMUs B-8, B-20/21, B-24, B-28, and the DD Area were to acquire data to confirm and quantify potential environmental contamination that would support corrective action decisions. Sampling and analysis of appropriate environmental media comprised the data collection tasks. Those analytical data provided the basis for the comparison of site-specific concentrations and appropriate Risk Reduction Standard(s) or protective concentration levels (PCLs). That task was accomplished by the data collection efforts for the subject sites. The risk evaluation supports selection of appropriate remedy standards, providing the basis for determining whether remedial action is necessary and justifying implementation of remedial action(s). This disposition assessment uses all the data and results from previous investigations at the five SWMU sites to screen, develop, and recommend remedial alternatives for the sifted soil piles to be addressed in this corrective measure program.
The objective of this report is to identify corrective measures for addressing contaminated soils that were stockpiled during soil sifting operations at SWMUs B-8, B‑20/21, B-24, B-28 and the DD Area. Various potential technologies are screened to determine their applicability to the stockpiled soil at these sites, and several alternatives are selected for more detailed evaluation. Numerous criteria are evaluated including estimated remedial lifecycle costs. Viable methods of remediating the soil contamination from the stockpiled soil at the subject sites are identified. Finally, based on the objective and subjective evaluation of the appropriate criteria, potential corrective measures are proposed for further field studies.
CSSA intends to remediate existing contamination or otherwise demonstrate a lack of threat to current and/or potential occupants or users of the facility as prescribed by the EPA.
As described in Section 4.3 of the Risk Assessment Technical Approach Document (Volume 1-6), CSSA has opted to pursue closure of SWMUs under the Risk Reduction Rule (30 Texas Administrative Code [TAC] �335). If the site exceeds background, then a determination will be made regarding the feasibility of cleaning the site to meet background concentrations. If the decision is made to clean the site to background, closure under RRS1 will be sought. However, if it is determined that the site cannot be closed to meet background concentrations, then the site will be closed under the Texas Risk Reduction Program (TRRP). A notification of intent to close sites identified to date (including SWMUs B-8, B-20/21, B-24, B-28, and the DD Area) in accordance with the Risk Reduction Rules was sent to the Texas Commission on Environmental Quality (TCEQ) on July 12, 1999. TCEQ acceptance of this notification was received on October 5, 1999.
Closure under RRS1 requires removal or decontamination of waste, waste residues, and contaminated operation system components; and demonstration of attainment of cleanup levels (30 TAC �335.554). If closure requirements under RRS1 are attained and approved by the TCEQ Executive Director, then the owner is released from the deed recordation requirement.
Since the contaminants of concern (COCs) in the stockpiled soils include metals, the cleanup levels are the background levels for metals. Background metals levels were statistically calculated for CSSA soil and the Glen Rose Limestone, and are reported in the Second Revision to the Evaluation of Background Metals Concentrations in Soil Types (Parsons, February 2002).
In September 1999, TRRP was made effective. Upon review of the Rule, CSSA decided to seek closure of the sites under the RRS1. However, TRRP provides a means to evaluate site concentrations against PCLs determined by the state to be protective of human health and the environment. To protect the commercial/industrial worker against exposure to contaminated surface soil, the TCEQ provides a look-up table for Tier 1 PCLs. The PCL for lead that is protective of the worker exposed through ingestion, inhalation, and dermal contact with contaminated soil (TotSoilComb PCL) is 1,600 milligrams per kilogram (mg/kg). The PCLs for all chemical of concerns for the sifted soils are provided in the analytical results tables for comparison purposes.
To protect groundwater at a site from becoming contaminated at levels greater than the groundwater PCL, the TCEQ provides a means for calculating site-specific groundwater protection PCLs for soil based on the type and pH of the soil. The methodology presented in �350.73(e)(1) can be used to calculate site-specific groundwater protection PCLs.