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HomeMy WebLinkAboutPN_Project_Narrative_180621_v1.pdf 2731 Wetmore Avenue, Suite 402, Everett, WA 98201  Phone (425) 493-5221 Fax (425) 374-5152 otak.com Project Narrative The King County Department of Natural Resources and Parks, Parks and Recreation Division, is proposing the May Creek Trestle Rehabilitation Project. The project intends to repair and retrofit the May Creek trestle bridge. The trestle is currently used as recreational pedestrian bridge and is planned to become part of the multi-use Eastside Rail Corridor (ERC) regional trail in Renton. The trestle is deteriorated and has defects and is in need of repairs to provide continuous use of the trail system. A bridge inspection revealed defects and deterioration in timber members. Internal decay in timber piles, back walls and wing walls was observed. Repairs are recommended in order to utilize the bridge for the ERC Trail and to accommodate for the desired lifespan of the structure. In addition to repairs and rehabilitation of existing components of the trestle bridge, existing timber railroad ties, steel railroad tracks and fencing will be removed, and new decking and railing will be installed. The project is located in the City of Renton, King County, Washington. The May Creek trestle is located approximately 300 feet north of N. 41st Street, west of Lake Washington Boulevard. The project is located in Section 32, Township 24 North, Range 05 East of the Public Land Survey System. The May Creek trestle is approximately 60 feet long and 13 feet wide. The project is anticipated to occur in July 2018 and to be completed in October 2018. The site is zoned R-10- Residential 10 dwelling units per acre. The site’s comprehensive plan designation is RHD-Residential High Density. The shoreline master program designation of the site is Urban Conservancy. A Tier 1 Grading License Permit and this Conditional Use Permit from the City of Renton will be needed for this project. A Certificate of Exemption from Shoreline Substantial Development has been issued (April 13, 2018) and is included with this permit packet. The project is covered by an existing HPA for bridge maintenance and will not require an additional HPA. No wetlands are located within the vicinity of the project site. May Creek is located below the trestle bridge and flows east to west. The stream is a perennial tributary to Lake Washington and is Type S (Shoreline of the State) per Washington State Department of Natural Resources (DNR) and the City of Renton (City). The project will occur above the ordinary high water mark to repair portions of the trestle that span the stream. Two piles are proposed to be repaired, using only hand tools and personnel (no motorized equipment), within the ordinary high water mark. The Natural Resources Conservation Service (NRCS) mapped soils include Norma sandy loam in the project area. The proposed project includes repairs to existing components of the bridge, and new decking and railing will be installed in the same footprint of the existing features. No views will be obstructed as construction will occur within the same footprint of the existing bridge. Components to be removed will be disposed of at an approved location. The May Creek trestle is located approximately 840 feet from the shoreline of Lake Washington. Shoreline in the vicinity of the project area is bordered by single and multi-family residences, private docks, and bulkheads. Residential units are located west of the project area and there will be no obstructions of existing Page 2 of 2 views. No trees or woody shrubs will be removed for this project and adjacent trees and woody shrubs will be protected with high visibility fencing during construction. No landscaping is proposed for this project. Two, approximately 200-square foot areas on the north east and south east ends of the bridge will be cleared for an access road/wheel wash area. These areas will be re-seeded with native vegetation after repairs are completed. No watercourse will be changed, altered, or relocated. Work will occur above the stream to remove timber ties and tracks and to install new decking and railing. The project will not impact flood zones, as all work will occur above the flood hazard areas and there will be no expansion of structures within the flood zone. There will be no impacts to utilities within the project area. A sewer line is located approximately 30 feet east of the trestle and a water main is located approximately 35 feet west of the trestle. Both utilities are outside of the project area and will not be affected by project related activities. Project limits can be seen on project plans included in this permit packet. The proposed project will not change the functioning characteristics of the structure. Less than 2000 square feet of new and/or replaced impervious surface is proposed for the new bridge decking. No pollution generating impervious surface is proposed. Under existing conditions, stormwater runoff from the bridge deck flows to the stream and uplands below. After construction, water will continue to flow from the bridge deck to the stream and uplands below. There will be no change in drainage patterns with respect to stormwater entering nearby waterbodies. The project is not anticipated to increase new traffic trips for AM and PM times. There will be no change in roadways or access to the trail system. Temporary changes in traffic may occur along Lake Washington Boulevard N and N 41st Street during project construction. The project will involve approximately 21 cubic yards (CY) of excavation for removal of the timber back walls and wing walls. There will be approximately 21 CY of replacement fill, consisting of new timber back walls and gravity block walls. There will be approximately 20 CY of temporary fill for the construction entrance. The site can be accessed by the trail connecting the trestle to North 41st Street in Renton. Three are no proposed off-site improvements. The project is being constructed in conjunction with the Ripley Lane trestle repair and retrofit, north of the May Creek project site. The total estimated construction cost and fair market value of the project is approximately $119,950.00.