ROD: Decision Summary

2.8. Summary of the Comparative Analysis of Alternatives

Ground Water
Unsaturated Zone

The remedial alternatives and associated treatment options were evaluated against nine EPA criteria in the FS and PRAP. The preferred remedial alternatives for ground water and unsaturated sediment were analyzed in terms of these nine criteria and are summarized in Tables 7 and 8.

2.8.1. Ground Water

Overall Protection of Human Health and the Environment.: All the ground water remedial alternatives are equally protective of human health (if institutional controls are in effect for Alternative 3 to prevent new or existing wells from being used) because each is designed to meetthe same cleanup criteria. Consequently, the resulting health risks are identical among the alternatives (Isherwood et al., 1990). Since Alternatives 2 and 3 would allow some continued migration of VOCs in ground water, they also allow some degradation of the subsurface environment.
Compliance with ARARs.: Ground water Remedial Alternatives No. 1 and No. 2 are designed to achieve all ARARs (Isherwood et al., 1990). However, Alternative No. 2 would allow higher-concentration VOCs in eastern LLNL to migrate across the site, and thus does not fully satisfy the State of California ARAR regarding non-degradation of water resources. Remedial Alternative No. 3, treat at point-of-use, though estimated to be protective of human health (Isherwood et al., 1990), does not fully satisfy the California non-degradation ARAR.
Long-Term Effectiveness and Permanence.: All three remedial alternatives are equally effective in terms of permanence and stability of remediation and reduction in health risks by removing and treating the contaminants.
Reduction in Toxicity, Mobility, and Volume.: Remedial Alternatives No. 1 and No. 2 reduce toxicity,. 1 does not allow additional contaminant migration beyond the current extent downgradient. Alternative No. 2 allows VOCs in eastern LLNL to migrate across the site. Remedial Alternative No. 3, deferred action, allows more contaminant mobility than Alternative No. 2 and does not reduce contaminant mobility until and unless contaminants reach domestic or municipal wells in concentrations above an MCL. ic or municipal wells in concentrations above an MCL.
An advantage of the UV/oxidation remediation technology (preferred at Treatment Facilities A, B, E, and F) is that TCE, PCE, 1,1-DCE, and FHCs are destroyed in one process, thereby minimizing waste requiring further treatment or disposal. Use of GAC requires regeneration of spent carbon to convert the captured compounds to harmless substances. Ion-exchange resins for metals removal may require disposal as hazardous waste.
Short-Term Effectiveness.: All the remedial alternatives would expose workers, the public, and the environment to negligible impacts during installation and operation.
The selected remedial alternative is estimated to achieve the remediation goals in about 50 years compared to 90 years or more for Remedial Alternative No. 2, which employs only four treatment facilities and ten extraction locations. Alternative No. 3 may take about 230 years to achieve remediation goals, and remediation may not begin for 200 years. Each treatment option, combined with the same remedial alternative, would require about the same length of time to achieve the remediation goals. For Alternative No. 1, it is estimated that plume containment and overall hydraulic control will be achieved in 1995. This estimate will be further refined in the Remedial Design.
Implementability.: Each of the remedial alternatives and technology options is technically and administratively feasible and supported by available services, materials, and skilled labor. An advantage of the UV/oxidation technology over the GAC technology is that regeneration of the spent carbon is unnecessary. The air-stripping-based and UV/oxidation-based technologies generate substantially less spent carbon than the GAC system for water treatment. UV/oxidation and GAC technologies also have minimal visual impact compared to air-stripping towers.
Cost.: The present worth of Ground Water Remedial Alternative No. 1 (the selected alternative) is estimated to be $103 million, assuming 50 years of operation. The present worth for 90 years of operation for Remedial Alternative No. 2 is $99 million. The present worth for Remedial Alternative No. 3 is $87 million, assuming air stripping is the treatment option used. If Remedial Alternative No. 3 consisted only of monitoring ground water for 100 years, the present worth would be $12 million.
State Acceptance.: The California RWQCB and DTSC accept the selected ground water remedial alternative, Remedial Alternative No. 1. The RWQCB does not accept Ground Water Alternatives No. 2 and No. 3 since they do not fully satisfy the California non-degradation ARAR.
Community Acceptance.: The community accepts the general concept of the selected alternative, but desires funding commitments, a detailed implementation schedule, continued opportunity for involvement, and a faster cleanup. Implementation schedules will be included in post-ROD documents called the Remedial Action Implementation Plan and the Remedial Design/Remedial Action reports. LLNL is continually exploring and implementing new methods and techniques that will accomplish the fastest cleanup.

2.8.2. Unsaturated Zone

The remedial alternatives for the unsaturated zone are described below and compared in Table 8 in terms of the EPA evaluation criteria.

Overall Protection of Human Health and the Environment.: Unsaturated Zone Remedial Alternative No. 1 is protective of human health and the environment and creates minimal health risks. Remedial Alternative No. 2 has some impact on the subsurface above the water table as contaminants would be allowed to migrate naturally. Estimates indicate natural processes would reduce the concentrations to below MCLs in 90 to 140 years (Isherwood et al., 1990, Appendix G).
Compliance with ARARs.: Remedial Alternative No. 1 is designed to achieve ARARs. Alternative No. 2 may allow contaminants to reach the ground water in concentrations exceeding MCLs in a few isolated places (i.e., the Gasoline Spill and Building 518 Areas, and perhaps the East Taxi Strip Area), and therefore does not meet the California non-degradation ARAR.
Long-Term Effectiveness and Permanence.: Both of the alternatives are effective in the long run and reduce health risks permanently by removing and treating contaminants.
Reduction in Toxicity, Mobility, and Volume.: Remedial Alternative No. 1 results in the immediate removal and complete breakdown of compounds to harmless substances, thereby permanently reducing toxicity, mobility, and volume. Remedial Alternative No. 2 (deferred action) allows VOCs and FHCs to continue to migrate through the unsaturated zone to the ground water. VOCs and FHCs would then be extracted and treated in the ground water at the nearest treatment facility.
Short-Term Effectiveness.: Both alternatives would expose workers, the public, and the environment to negligible impacts during installation and operation. Achieving the remediation objectives is estimated to require 10 years for the selected alternative, Alternative No. 1, and 90 years for Alternative No. 2.
Implementability.: Both alternatives are technically and administratively feasible and supported by available services, materials, and skilled labor.
Cost.: Present worth cost for 10 years of operation for the preferred alternative is $1.1 million. The preferred alternative utilizes the most cost effective treatment option available for both VOCs and FHCs. The present worth of Alternative No. 2 is $850,000.
State Acceptance.: The California RWQCB and DTSC accept the selected unsaturated zone alternative, Remedial Alternative No. 1. The RWQCB does not accept Unsaturated Zone Alternative No. 2 since it may allow ground water degradation.
Community Acceptance.: The community accepts the general concept of the selected unsaturated zone alternative, but desires funding commitments, a detailed implementation schedule, continued opportunity for involvement, and a faster cleanup. Implementation schedules will be included in post-ROD documents called the Remedial Action Implementation Plan and the Remedial Design/Remedial Action reports. LLNL is continually exploring and implementing new methods and techniques that will accomplish the fastest cleanup.

2.9. The Selected Remedies

Contact Webmaster

LLNL Disclaimers

Rev. 6/2/97

UCRL-AR-109105

UCRL-MI-127711 | Privacy & Legal Notice

October 1, 2007

Lawrence Livermore National Laboratory
7000 East Avenue • Livermore, CA 94550

Operated by Lawrence Livermore National Security, LLC, for the Department of Energy's National Nuclear Security Administration