2011/05/18 Council Agenda Packet

•" F n EGERETT OttGO010I. .( 1DA ITEM CO' ER S ET PROJECT TITLE: 1 Union Slough Bridge Removal Briefing COUNCIL BILL# Project Management Plan Proposed Action Originating Department Public Works Consent Contact Person Heather Griffin Action Phone Number (425) 257-7206 First Reading FOR AGENDA OF May 18, 2011 Second Reading Third Reading Initialed by: Public Hearing Department Head Budget Advisory CAA Council President Location Preceding Action Attachments Department(s) Approval Smith Island/Union 7/14/2010 Presentation Site Map &Project Legal Slough for Trail Relocation Management Plan Amount Budgeted $2,600,000 Expenditure Required $900,000 Account Number(s): UP2969 Budget Remaining $1,500,000 Additional Required _0- DETAILED SUMMARY STATEMENT: In 2003 City Council authorized the Mayor to sign a Project Cooperative Agreement with the US Army Corps of Engineers to partner in a 93-acre intertidal wetland restoration project at Smith Island on Union Slough east of the Water Pollution Control Facility (WPCF) Oxidation Pond. The joint project consists of two parts: a southern cost-shared federal project that is 35-acres in size and a northern advanced mitigation site fully funded by the City that is 58-acres in size. Design and construction were completed by the Corps per the Project Cooperative Agreement. In 2003/04, a new setback dike was constructed by the Corps to provide flood protection for the WPCF. In 2007, tidal influence was restored to the joint project site following the excavation of three 180-ft breaches in the old flood control dike and the placement of three bridges. Immediately upon opening the site to tidal influence the northern bridge settled significantly, and,in the years since, significant scour has undermined the foundations of all the bridges. Lack of complete flushing prevented sediment exposure and colonization of intertidal wetland vegetation. Advanced Mitigation credits at the City's site cannot be obtained until additional action is taken to remedy the problems. The City and Corps have come to the conclusion that the best, least expensive option to address both the structural and drainage issues is to remove the bridges. The attached Project Management Plan provides for the City's contribution to this work. Construction can only take place during a limited in-water work window between July and October due to the presence of salmonids in Union Slough. The City needs to provide funds at this time in order for the project to be bid. Additional funds may be required depending on bid prices for the work. The Corps has committed an amount up to their $5 million funding limit for the overall project. To-date the Corps has contributed $3.8 million to the joint project and the City has contributed$4.3 million to the project. RECOMMENDATION: Authorize the Mayor to sign the Union Slough Bridge Removal Project Management Plan which commits $900,000 to the project. 1