Res to approve task assignment 26 for Westside Road

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Westside Road Improvements Scope of Work Kittitas County would like to improve Westside Road from mile post 1.98 to mile post 5.81. The improvements will include: widening the road, improving shoulder slopes, improving guardrails, beveling culverts, and improving sight distance at intersections. Sargent Engineers has been asked to complete the environmental documentation, complete the geotechnical study, and develop the plans, specifications, and estimate for the project. This project was previously started under a different task order. In order to do this, Sargent Engineers will perform the following tasks: Land Survey Additional survey will be performed at the west end of the project. This survey will be sufficient to add approach rails to the bridge that crosses the Hiline canal. This will be added to the base map that has already been prepared for the project. Hydraulic Analysis There is only one stream that crosses Westside Road and that culvert is not to be disturbed. So there will not be any hydraulic analysis for this project. Drainage Design Improved drainage is not part of the prospectus for the project. Therefore, the natural drainage will be preserved and enhanced, but no treatment, detention, or retention of the stormwater is planned. A formal drainage analysis will not be performed. Geotechnical Study PanGEO will perform all geotechnical engineering for the project. PanGEO will need to provide site specific recommendations for cut and fill slopes that are steeper than typical standards, and they will need to provide design recommendations for gravity (ecology) block walls and soldier piles walls at other locations where steepened slopes are not feasible. Geotechnical Engineering Analyses Geotechnical recommendations for design of the roadway widening will be developed in general accordance with load and resistance factor design (i.e., AASHTO LRFD Bridge Design Specifications, 2nd Edition, with Interims and the current WSDOT Bridge Design Manual). The analyses will include: Widening Alternatives Analysis — Considering the roadway geometry and underlying soil and groundwater conditions, they will develop schematic widening support options for the County road that will include cantilever soldier pile walls, gravity (ecology block) walls, and cut and fill slopes. Because of the right of way constraints, they will conduct a site reconnaissance to assess the feasibility of using steeper than normal cut slopes at different locations along the alignment to remain within the right of way and avoid the use of walls. They will prepare sketches of these options for review and concurrence before developing specific design recommendations for viable alternatives. Wall Design Recommendations - Pending concurrence on feasible alternatives for the roadway widening, they will develop recommendation for the embankment support including: 0 Cut and Fill Slopes