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Remedial Action at IRP Sites 8, 11, and 12, Former MCAS El Toro, CA
 

Accord Engineering was awarded a firm-fixed-price contract to remove contaminated soil associated with three sites that were used as a DRMO yard, sludge drying bed, and transformer storage yard, respectively. These properties needed to be cleaned up to facilitate the property transfer of this closed MCAS and for future development of this prime real estate in Orange County, CA.

The remediation was reclassified from a non-time-critical removal action (Site 11) to a CERCLA remedial action (Sites 8 and 12) to be performed under the direct supervision of the Base Closure Team (BCT) consisting of the California Department of Toxic Substances Control (DTSC), the U.S. EPA  Region IX (U.S. EPA), Santa Ana Regional Water Quality Control Board (RWQCB), and the U.S. Department of the Navy. The BCT also interacted closely with a Restoration Advisory Board (RAB) made up of local community members and stakeholders. The work had to be performed in accordance with a tight schedule pre-determined by the Base Closure Plan.

In 2005, Accord Engineering completed the Site 11 removal action in accordance with the Record of Decision.  Accord Engineering developed an Action Memorandum, and the removal action plan consisted of a quality assurance project plan, site contingency plan, waste management plan, environmental control plan, stormwater pollution prevention plan, project health and safety plan, and transportation/traffic control plan to meet various environmental compliance requirements identified in the Applicable or Relevant and Appropriate Requirements. The plans were subsequently reviewed and approved by the BCT and RAB through the required public review/comment process. Between June and July 2005, Accord conducted the field remediation at this former transformer storage site to remove soils contaminated with PCBs and pesticides. The fieldwork consisted of demolition of reinforced concrete foundations next to a warehouse and subsequent soil excavation. Approximately 1,500 cubic yards of concrete slab and soils were demolished and removed for off-site disposal. Accord Engineering conducted post-excavation environmental sampling to verify that the contamination was removed to meet the site-specific cleanup goals. The site met the risk criteria and was approved for no further action by the BCT signatories. Accord Engineering completed the project within schedule and below budget as a result of effective waste management that minimized the disposal costs. The project maintained a zero-accident record over the entire field operation.

The excavation area was immediately next to a two-story warehouse building. It was critical to maintain the integrity of the building foundation throughout the entire excavation. In order to avoid using conventional shoring devices, which would further restrict the already limited access to the excavation, Accord Engineering implemented the following actions:

  • Obtained approval from the BCT to perform pre-excavation confirmation sampling to fully delineate the excavation boundary and extent;
  • Developed an excavation sequencing plan so that the excavation face was staggered and would not have any unsupported opening for more than 20 feet;  and
  • Backfilled the open excavation with quick-set concrete if the excavation was deeper than the building foundation footings so that the foundation area was quickly restored within the same day.

Accord Engineering was able to complete the excavation and confirmation sampling on schedule and without any incidents. The site was fully restored to below cleanup levels, even in areas with very difficult access.

 

 
More pictures from this very important project