SWMU B-20 Investigation Report Addendum Appendix G - Preliminary Evaluation of Remedial Alternatives

Section 3 - Analysis of Alternatives

3.1 - Site-Specific Evaluation Criteria

During the analysis of the alternatives, each of the three alternatives was assessed against the following evaluation criteria:

The following is a brief discussion of each criterion as it was interpreted with respect to the specific circumstances of the B-20 site.

The Remedial Action Objective (RAO) to be satisfied by each alternative is to eliminate risk associated with direct human contact (dermal and ingestion) with contaminated soils.

Compliance with primary ARARs is to satisfy the Texas Risk Reduction Standard 1 (RRS1) and EPA requirements.

This evaluation also examined the risk of short-term pollution exposure, physical injury and damage to site workers, community residents, community structures, and the greater environment during the implementation of each alternative. The assessment of long-term effectiveness and permanence included in the "durability" of actions to block pollutant pathways and teh minimization of monitoring requirements. The evaluation of toxicity, mobility, and volume was based on the degree to which the metals and explosive contaminants were contained, treated, or removed from the site. Implementability was addressed based on the difficulty to apply the alternative to the site. Technical considerations included the reliability and proven application of the technologies involved. Administrative considerations included the complexity of land use restrictions (if implemented) and long-term monitoring obligations. Protection of human health and environment was assessed based on the overall effectiveness of the alternative to block pathways for human exposure to the contamination.

A preliminary construction cost estimate was prepared for each alternative. The estimate is accurate within -30% to +50% for the assumptions provided in the cost table and in the discussion of each alternative. The unit costs are based on Parsons ES experience and historic information obtained by Parsons ES for similar projects or construction items.

3.2 - Criteria Evaluation of Alternatives

Each of the three alternatives retained from Section 2 will be evaluated using the specific criteria presented in Section 3.1. The summary results of the evaluation are presented in Table 3.1.

3.2.1   Alternative 1: No Action

RAO:

For Alternative 1, the RAO would not be met. The site would stay as it is. Any risks associated with the site would continue to exist.

ARARs:

Due to no action, Alternative 1 would not meet any ARARs or any Texas Risk Reduction Standards (RRS1, RRS2, and RRS3).

Short-Term Risks:

As there would be no action, there would be no short-term risks.

Long-Term Effectiveness and Permanence:

Alternative 1 would not represent a permanent solution.

Reduction of Toxicity, Mobility, and Volume:

There would be no change in toxicity, mobility, or volume of the contaminaiton.

Implementability:

This alternative is implementable as there would be no action to implement.

Protection of Human Health and Environment:

Protection of human health and environment would not be achieved.

Cost:

There would be no cost associated with this no action alternative.

3.2.2   Alternative 4: Hot Spot Excavation and Offsite Disposal

RAO:

The RAO would be partially satisfied by the removal and offsite disposal of the soils with contamination levels above RRS2 and by filling the craters to eliminate ponding, as the remaining soil with contamination levels above RRS1 would have potential risks to human health and the environment if land use changes.

ARARs:

RRS1 criteria would not be met.

Short-Term Risks:

The short-term risks would be minimized by following proper health and safety procedures during excavation and transportation of the contaminated site soils.

Long-Term Effectiveness and Permanence:

This alternative would not be a permanent solution for this site as deed restrictions would be required.

Reduction of Toxicity, Mobility, and Volume:

The mobility of the contaminants in the "hot spot" soils would be significantly reduced by the containment at permitted offsite landfill(s). The volume of the waste soil at the site would be reduced slightly. But overall, volume of contaminated material would not be reduced. There would be no reduction of toxicity in the soil contaminants.

Implementability:

Since this alternative consists of proven conventional technologies, it would be implementable technically. It would be considered implementable administratively although there would be restrictions on land use. There are no restriction on disposal of site waste soils at permitted landfill(s).

Protection of Human Health and Environment:

The removal and offsite disposal of the "hot spot" soils and the filling of craters would be protective of human health and the environment as long as the site remains under "industrial" use.

Cost:

The total capital cost, which is also the present worth cost, was estimated at $0.2 million. A detailed breakdown of the cost components is presented in Table 3.2.

3.2.3   Alternative 5: Excavation and Offsite Disposal

RAO:

The RAO would be satisfied by the removal and offsite disposal of all contaminated soils and by filling the craters.

ARARs:

RRS1 criteria would be met.

Short-Term Risks:

The short-term risks would be minimal by following proper health and safety procedures during excavation and transportation of the contaminated site soils.

Long-Term Effectiveness and Permanence:

This alternative would be a permanent solution for this site as no contaminated soil would be left on site.

Reduction of Toxicity, Mobility, and Volume:

The mobility of the contaminants would be significantly reduced by the containment at permitted offsite landfill(s). The volume of the waste soil at the site would be reduced to zero. But overall, the volume of contaminated material would not be reduced. there would be no reduction of toxicity in the soil contaminants.

Implementability:

Since this alternative consists of proven conventional technologies, it would be implementable technically. It would be implementable administratively as well, although permits for transportation and disposal of wastes would be required. There are no restriction on disposal of the site waste soils at permitted landfill(s).

Protection of Human Health and Environment:

The complete removal and offsite disposal of contaminated soils and filling of craters would be protective of human health and the environment.

Cost:

The total capital cost, which is also the present worth cost, was estimated at $2.8 million. A detailed breakdown of the cost components is presented in Table 3.3.

3.3 - Comparative Analysis of Alternatives

A summary of alternative analysis is presented in Table 3.1. Det6ailed comparative analysis of all three alternatives under each of the evaluation criterion is presented as follows.

RAO:

Alternative 1 would not meet the RAO. Alternative 4 would partially meet the RAO. Alternative 5 would completely meet the RAO.

ARARs:

Alternative 1 would not satisfy any ARARs. Alternative 4 would satisfy RRS2. Only Alternative 5 would satisfy RRS1, the desired closure standard.

Short-Term Risks:

Alternative 1 would have no short-term risk. Alternatives 4 and 5 would have similar short-term risks associated with excavation, although the risks would be more for Alternative 5 due to a larger volume of excavation involved.

Long-Term Effectiveness and Permanence:

Alternative 1 would not be effective or permanent. Alternative 4 would not be considered completely effective and permanent due to the deed restrictions required. Alternative 5 would be effective and permanent.

Reduction of Toxicity, Mobility, and Volume:

No reduction of toxicity, mobility, or volume of contamination would be achieved under Alternative 1. Both Alternatives 4 and 5 would reduce the mobility of the contamination to a limited extent and to a significant extent, respectively. But no reduction of toxicity or volume of contamination would be achieved under either Alternative 4 or 5.

Implementability:

Alternative 1 would have no actions to implement and therefore would have no implementation difficulties. Alternative 4 would be considered implementable, however, deed restriction would be required to limit future land use. Alternative 5 would be fully implementable.

Protection of Human Health and Environment:

Alternative 1 would not be protective of human health and environment. Alternative 4 would be protective of human health and environment under restricted land use conditions. ALternative 5 would be fully protective of human health and environment by offsite disposal of all contaminated soils at permitted landfill(s).

Cost:

Alternative 1 would not incur any cost and Alternative 4 would cost an estimated $0.2 million. Alternative 5 would cost an estimated $2.8 million.