Our Projects

Copper Mine Remediation Project

Copper Mine Remediation Project

Holden Mine was a copper mine active from 1938 to 1957. Through acquisition of former operators, Rio Tinto took over remediation of the relic copper mine as required by the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). Phase 1 of the Remedial Action (RA) encompassed 170 acres and caused both temporary and permanent impacts […]

Critical Areas Mitigation Site Monitoring Services

Critical Areas Mitigation Site Monitoring Services

King County Department of Natural Resources and Parks (DNRP) has constructed multiple critical areas mitigation sites as required by the local jurisdictional code to offset impacts from DNRP projects across King County. Confluence managed consecutive contracts from 2015-2020 to perform post-construction mitigation site monitoring and reporting for numerous such mitigation sites. Monitoring efforts typically included […]

McSorley Creek Pocket Estuary Restoration Project at Saltwater State Park

McSorley Creek Pocket Estuary Restoration Project at Saltwater State Park

Confluence worked with King County on this project that will reconstruct the beach front, nearshore, tributary stream, and park design of Saltwater State Park to enhance habitat for salmon. Key features of the project include realigning McSorley Creek to restore stream and estuary habitat and the removal of marine shoreline armoring to create a dynamic […]

Ovenell Farm Proposed Park Critical Areas Study and Master Planning

Confluence delineated wetlands on this 16.75-acre site.

Ovenell Farm Proposed Park Critical Areas Study and Master Planning

The City of Stanwood’s Community Development Department is developing a master plan to convert a former dairy farm, the “Ovenell Farm,” into a park and historical site. Confluence has conducted several tasks to support the master planning process and future permitting for this project, including completing a wetland and ordinary high water mark delineation, Shoreline […]

Culvert Replacement Corps Permitting and Engineering Review

Culvert Replacement Corps Permitting and Engineering Review

Snohomish County Surface Water Management (SWM) proposed 29 culverts and 2 water quality facilities for replacement as part of a program to improve fish passage and habitat conditions. Confluence managed the effort to determine applicable U.S Army Corps of Engineers (Corps) regulatory requirements for the proposed projects. Confluence worked with design engineers to assess field […]

Mukilteo Ferry Terminal Replacement Project Environmental and Tribal Services

Mukilteo Ferry Terminal Replacement Project Environmental and Tribal Services

In 2020, Washington State Department of Transportation completed construction on the new Mukilteo Ferry Terminal, part of the State Route 525 transportation corridor connecting the Seattle-Everett metropolitan area to Whidbey Island. The project involved removal of a 3,000-foot-long pier supported by 4,000 creosote-treated piles, and dredging of potentially contaminated sediments beneath the existing pier, followed […]

Aberdeen Mill Wetlands Restoration/Mitigation & Mitigation Monitoring

Aberdeen Mill Wetlands Restoration/Mitigation & Mitigation Monitoring

Confluence provided permitting assistance for the construction of a new stud mill in Aberdeen, WA. Work included field surveys on over 100 acres of the project site to delineate wetlands, identify mitigation opportunities, and evaluate fish and wildlife habitat. Confluence prepared the wetland delineation report, JARPA, and biological assessment for Section 7 consultation under the […]

Environmental Permitting for Industrial Property Development

Environmental Permitting for Industrial Property Development

Sierra Pacific Industries (SPI) developed industrial land in Frederickson, Washington. Confluence Environmental Company served as the lead consultant for site SEPA; critical areas studies; off-site wetland mitigation design and planning; environmental review; and local, state, and federal environmental permitting for the property.  Confluence led the multi-disciplinary team from design of site development through design of […]

North Mercer Island Interceptor and Enatai Interceptor Upgrade Project

North Mercer Island Interceptor and Enatai Interceptor Upgrade Project

King County Wastewater Treatment Division is upgrading the King County sewer system from the North Mercer Island Pump Station to Sweyolocken Pump Station in Bellevue. Phase 1 included a multi-stage alternative analyses process. For this project, Confluence provided technical expertise related to wastewater conveyance and infrastructure work in sensitive habitats such as the Mercer Island […]

SR520 Bridge Replacement Program – Permitting/ESA/Mitigation/Cultural Resources

SR520 Bridge Replacement Program – Permitting/ESA/Mitigation/Cultural Resources

Washington State Department of Transportation (WSDOT) is replacing the State Route (SR) 520 bridge. The work is divided into three projects: West Side/Floating Bridge, East Side Transit and HOV, and Pontoon Construction. Confluence’s leadership in implementing the environmental strategy has enabled WSDOT to meet a very aggressive schedule for environmental project delivery on one of […]