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Conti successfully completed the construction of a 450 linear foot interceptor trench, 19 feet below grade. The team installed Light Non-Aqueous Phase Liquids (LNAPL) skimming pumps in collection sumps that operate on compressed air. A temporary shed to house the treatment system, pump controls, air compressor and electrical components required to safely run the treatment system was also constructed.

Significant previous experience in field excavation and installation facilitated Conti’s safe and immediate response to UXO at the trench site. During trench installation, the team encountered UXO items (large former Naval sea mines and ice breakers). Conti implemented immediate emergency procedures to safely identify and remove UXO items; mobilized a SUXO to the site, prepared removal plans and coordinated with the UXO subcontractor and the Navy EOD. Following removal of over 22 items, Conti stopped work until the remainder of UXO was cleared under a separate contract. Conti then returned to the site and completed trench and system installation within scheduled deadlines while coordinating work efforts with neighboring local development contractors. Conti also performed operations and maintenance (O&M) services on the treatment system.

Key features of the project included:

  • Site preparation and demolition – demolish and off-site dispose of existing Concrete Masonry Unit (CMU) building, concrete building slab, specific areas of fencing
  • Installation of the NAPL interceptor trench: 450 linear feet of collection trench 19 feet below grade; horizontal HDPE piping within the trench; 20-mil plastic barrier
  • Installation of the LNAPL recovery and storage system: pumps, skimmers, storage tank, pump controls, air compressor, and electrical components
  • Excavation, sampling, and analysis of excavated soil and disposal
  • Perform waste characterization packaging, transportation, and disposal
  • Implement emergency procedures to identify and remove UXO items
  • Prepare UXO Avoidance Plan, Ordnance and Explosives (OE) Construction Support Plan