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Soil Pile Disposition Assessment
Section 7 - Development of Corrective Measure Alternatives
The remedial technologies that passed the preliminary screening process have been assembled into alternatives to be considered for remediation.
Preliminary screening was performed for each alternative to consider three broad criteria: effectiveness, implementability, and cost. The purpose of this screening is to identify the alternatives that are technically feasible and as a result reduce the number of alternatives retained for detailed analysis. The alternatives determined feasible will be retained for detailed analysis.
The purpose of this section is to combine the treatment technologies retained after the screening analysis into remedial action alternatives. A variety of alternatives were assembled to address the soil contamination. The feasible remedial alternatives considered for detailed analysis include:
Alternative 1: No action;
Alternative 2: Density Separation/Phytoremediation; and
Alternative 3: Excavation, treatment, and off-site disposal.
This section describes each of the three alternatives. This is followed by a discussion of each alternative�s effectiveness, implementability, and relative costs.
7.1 - Alternative 1: No Action
The no-action alternative assumes no further remedial activities will be undertaken at the site. It is the baseline for comparison with the other alternatives for SWMUs B-8, B‑20/21, B-24, B-28, and DD Area and will therefore be retained for detailed evaluation.
Effectiveness: The no action alternative will not reduce the mobility, toxicity or volume of contamination. The volume of the contaminated soils is not expected to increase as the contaminants are stable throughout the media. Therefore, the no action alternative is considered to be moderately effective.
Implementability: There are no barriers to implementation.
Cost: There are no costs associated with this alternative. The no action alternative will be considered for further evaluation.
7.2 - Alternative 2: Density Separation/Phytoremediation
In general, the level of site characterization necessary to support an evaluation of density separation/phytoremediation is more detailed than that needed to support active remediation. A quantitative understanding of source mass, contaminant flow, contaminant phase distribution and partitioning, rates of uptake, and an understanding of the variability of these factors is required. Data showing a clear and meaningful trend of decreasing contaminant mass and/or concentration over time, as well as appropriate geochemical data to demonstrate the types of phytoremediation processes active at the sites are required to support the choice of density separation/phytoremediation as a remedy.
Once the contamination and geochemical environment are completely characterized, implementation of density separation/phytoremediation will require annual monitoring to confirm the efficacy of this remedial solution.
Effectiveness: Density Separation/Phytoremediation has not been thoroughly documented in the literature.
Implementability: Density Separation/Phytoremediation is rapidly gaining regulatory acceptance as an alternative for addressing contamination. There are no physical barriers to implementing this option at CSSA. With appropriate education (e.g., meetings, presentations, or press releases), the public should be receptive to the density separation/phytoremediation alternative.
Costs: The costs for implementing density separation/phytoremediation alternative generally are high relative to the presumptive remediation technologies. If monitoring must continue for a long period, however, the present-worth costs of density separation/phytoremediation with monitoring may not appear significantly lower than those for capital-intensive or maintenance-intensive options operating within a shorter time frame. This alternative will not be retained for detailed evaluation.
7.3 - Alternative 3: Excavation, Treatment and Off-site Disposal
This alternative involves excavation of contaminated soils, treatment with a soluble phosphate stabilization (PIMS) and transport to an acceptable off-site disposal facility as a Class 2 non-hazardous waste as defined in 30 TAC Chapter 335 Subchapter R. The interim actions already completed at the SWMU B-20/21 site comprise a portion of this alternative. Sifted soils were removed to perform field treatability study efforts associated with the use of PIMS and placed back onto the site for monitoring efforts.
Effectiveness: In general, excavation, treatment, and off-site disposal is an effective alternative when addressing contaminated soils less than 20 feet bgs. This alternative was already undertaken as part of the IM actions completed at SWMU B-20/21. The remaining contaminated soil is within the remaining SWMUs of concern.
Implementability: This alternative is technically implementable and has been proven effective at many other sites on CSSA.
Costs: Estimates for excavation and disposal range from $15 to $65 per cubic yard depending on the nature of materials and methods of excavation. These estimates include excavation/removal, transportation, and disposal at a permitted facility. The excavation, treatment, and off-site disposal alternative will be considered as a viable alternative.