Cleanup of Rural Town

Former Railroad Fueling Facility – Skykomish, WA

sky aerial croppedCRETE principals provided project management and environmental and civil design services for one of the largest petroleum cleanups in Washington State. The site is impacted by diesel and Bunker C dissolved in and floating on groundwater resulting from decades of locomotive fueling operations. Contamination had impacted soil and groundwater below a small town in the Cascade foothills and seeped into an adjacent river and wetland.

The comprehensive cleanup of river sediments, upland residential and commercial areas, wetlands, and the industrial facility included:

  • Excavation below Town including relocating and replacing structures and infrastructureSky dozer and bldg
  • Excavation and replacement of a vital flood control levee and nearby river sediment
  • Excavation and restoration of wetlands
  • in situ biological treatment of diesel-impacted soil and groundwater
  • Installation of a funnel-and-gate hydraulic containment system with reactive media
  • Treatment of groundwater and floating product using an integrated and fully automated product skimming/collection, and groundwater treatment system

The cleanup project occurred over a five-year active construction period.

Work Performed

  • Regulatory negotiations – MTCASky vault
  • Upland and waterfront RI/FS
  • Bench testing of surfactant/polymer enhanced flushing and chemical oxidation
  • Permitting – in-water cleanup, floodway, wetlands, historic landmarks, cultural resources, utilities, WSDOT
  • Petroleum upland and sediment cleanup
  • Shoreline design and cleanup
  • Construction plans and specifications
  • Wetland restoration
  • Construction oversight
  • Construction stormwater treatment

Value Added

  • Negotiated a soil protective of groundwater remediation level that was more than 150 times greater than the cleanup level
  • Demonstrated that organic acids were causing elevated TPH results
  • Designed a cofferdam to contain NAPLs and silt during nearshore excavation
  • Designed an innovative funnel-and-gate groundwater containment system with reactive media while protecting the railroad mainline
  • Managed a design team of 15 firms and over 35 engineers and construction managers
  • Integrated mechanically stabilized earth walls during backfill to provide a near vertical face for the next year’s excavation and to protect newly constructed improvements
  • Managed uncovered cultural resources during mass soil excavation
  • Documented and protected historic structures within the project footprint
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