Skykomish Remediation Project
Strider was the General Contractor for the BNSF Skykomish Environment Remediation Project in Skykomish, WA, during its time labeled the largest Department of Ecology project in the State of Washington. This project was certainly unique, with its combination of a heavy civil project set in the context of a remediation site with an extremely sensitive and diverse political/regulatory landscape. This environmental remediation project required extensive research and exploration, design and engineering, heavy civil construction, and public outreach. Strider played a central role in this process which allowed us to work with a vast array of professionals to include engineers (civil, environmental, geotechnical, and structural engineers), archeologist, scientists, attorneys, regulatory agencies, and public officials. This project required a higher level of sophistication not typically required of the contractor. Strider consistently assisted with the design process by providing solutions to improve constructability and reduce cost. After the design was finalized our approach to the work was presented in the Technical Execution Plan (TEP). The TEP was a comprehensive plan submitted to DOE specifying our proposed means and methods to execute the work. Items included in this plan are but not limited to: project coordination, schedule, temporary facilities and controls, site preparation, phasing, turbidity prevention to the Skykomish River, demolition, excavation, dewatering, oil recovery, structure relocations, utility work, construction water treatment, site restoration, and health and safety. With ever changing site conditions these project plans were continuously updated and submitted to the agencies. Strider joined this multi-year fast tracked cleanup project in 2008 and with our proven performance the contract was extended through completion, which occurred in 2011. A brief description of each scope (by year) is provided below. For more information on this project please see www.skykomishcleanup.com and http://www.ecy.wa.gov/programs/tcp/sites/bnsf_sky/bnsf_sky.html. 2008 Skykomish Remediation Project This phase installed 1,200 LF of sheet pile wall to provide containment and allow removal of 60,000 CY of soil, half of which was impacted by oil and required off-site disposal. The excavation site (the main street in the Town of Skykomish) was backfilled and restored with all new utilities, asphalt paving, and site amenities. To accommodate the work, three structures (residential and commercial) were temporarily relocated and returned. The sheet pile wall serves as the spine of a subterranean hydraulic control structure which channels groundwater flows through processing vaults so the contaminants can be removed and treated. Strider also constructed the groundwater pump and piping system and permanent water treatment facility. This scope included ten major vaults (65 tons each), 40 lesser vaults, and 16,000 LF of HDPE and 18,000 LF of PVC pipe and conduit. Other major scopes of work included oil recovery from the excavations and treatment of all construction water. 2009 - 2010 NWDZ Skykomish Remediation This phase required remediation and restoration of the North West Developed Zone (NWDZ), the most populated and complex section of the project. The scope of work includes first relocating and/or demolishing several commercial (to include a 4-story hotel) and residential structures within the excavation limits. Excavation of approximately 110,000 CY of soil occurred, with an estimated 86,000 CY being impacted and requiring offsite disposal. The remedial excavation process involved implementation of various support operations to include oil recovery (to remove free product), dewatering, and water treatment. Following excavation the site backfill operation required importing over 150,000 TN of structural fill and stabilization aggregate. Restoration of the town included moving back and restoring the displaced structures, installing all new utilities, sidewalks, and roadways. 2010-2011 Skykomish Remediation To complete remediation in Skykomish, BNSF extended Strider’s scope of work to include, excavation around the 5th Street Bridge (WSDOT Bridge from Hwy 2 to the Town of Skykomish), in the Skykomish River, the Former Maloney Creek wetlands, and rail yard. These scopes required significant in-water work to be performed under very stringent regulatory requirements. Work in the Skykomish River involved installation of energy dissipation structures, primary and secondary cofferdams for containment, down river sediment and oil recovery provisions, and water treatment. In-water excavation of oil contaminated soil was conducted and testing was performed to insure permit cleanup levels were met. Similarly, remedial excavation in the Maloney Creek wetlands required cofferdam containment with surface and ground water control and treatment. Following remediation, the river channel and levees were reconstructed and, new wetland habitat was constructed in the Former Maloney Creek. Overcoming the complexities and uncertainties associated with performing this level of work, the project was completed ahead of schedule and well under budget.