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7.1 - Statement of Objective

This addendum to the work plan describes activities in support of Interim/Stabilization Measures (IM) and characterization of the SWMUs O-1, B-8, B-20, B-24, B-28 and DD area, and in support of groundwater sampling and mapping at CSSA. This work plan has been developed to comply with the EPA Administrative Order on Consent, EPA identification number TX2210020739, proceeding under Section 3008(h) of RCRA, as amended, 42 U.S.C. Section 6928(h).

The objectives of the IM, anticipated to be necessary to satisfy regulatory requirements for future closure of the SWMUs identified in this plan, are to:

In addition to this addendum to the work plan, addenda to the FSP, which discusses field procedures, and the HSP, which details health and safety procedures, involved in the implementation of the IM are included in Volumes 1-4 and 1-5, respectively.

A detailed description of the interim measures which will be conducted at O-1 can be found in the RL74 Work Plan Addendum for SWMU O-1 (see SWMU O-1 Links). In brief, these measures include drilling to identify the extent of contaminated soil; excavation, stabilization, and disposal of contaminated soil; and site restoration (backfilling).

Groundwater interim measures are described in detail in the groundwater work plan (See Groundwater Links). Quarterly groundwater sampling of site wells is planned. In addition, as an IM, three off-base privately-owned wells will be sampled to verify that contamination has not migrated off-site.

Finally, this addenda also addresses contaminated soil at B-8, B-20, B-24, B-28 and DD. A large volume of soil was excavated at these sites during UXO removal activities (approximately 9,000 cubic yards). Because the volume of soil excavated is so large, and chemical concentrations in the soil have not yet been fully characterized, remediation of this material must follow a phased approach to ensure that an appropriate and cost-effective remediation technique is used. Therefore, the descriptions of IM activities included behind the individual site tabs provides for a phased approach.

7.2 - Closure Methodology

Planned IM activities for closure of the SWMUs have been developed to comply with all appropriate regulatory requirements for closure of solid waste management units as stated in 40 CFR, part 265 and 30 TAC 335, subchapters A, E, and S. A discussion of these closure requirements may be found in Section 2 of the Work Plan Overview.

7.3 - Reporting Requirements

Reporting requirements for the IM, outlined in the 3008 Order, will be met and have a format similar to that described in Section 3. Aside from the addendum to the Work Plan for the IM, two different types of reports are required. First, the IM Report is due within 60 days after data validation for the completion of the construction of the IM is complete and second, quarterly progress reports are to be submitted to the EPA beginning 120 days from the effective date of the 3008 Order.

The IM Report shall include:

Also included in the IM Report will be copies of inspection summary reports and data sheets, problem identification and corrective measures reports, block evaluation reports, photographic reporting data sheets, a design engineer’s acceptance reports, justifying documentation for deviations from design and material specifications, and as-built drawings.

The Quarterly Progress Reports shall include:

Also included in the Quarterly Progress Reports will be copies of daily reports, inspection reports and laboratory and monitoring data.

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