Reso 2020-036 - Laserfiche WebLink

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Cooperative Agreement — Estudillo Canal B. General Scope of Project To address the channel capacity deficiency downstream of UPRR, the District conducted a hydraulic study on the effect of temporarily diverting high flow in the channel to the adjacent City -owned sediment handling basin. The temporarily diverted high flow would then drain back into the Estudillo Canal within approximately 48 hours. The study concluded that temporary diversion of high flow into the City basin is feasible and would help lower the 100 -year water surface elevation in the channel downstream of UPRR. 2. The District plans to reconstruct the existing deteriorating tide gate structure approximately 465 feet upstream of the Monarch Bay Drive Bridge. The reconstructed tide gate structure would also be adaptable to future sea level rise. 3. The District plans to lower approximately 305 linear feet of the Estudillo Canal south levee approximately 500 -feet downstream of UPRR. Articulated concrete block mat will be installed on the south side of the lowered levee to protect the embankment from erosion and scouring. A new drainage structure with three thirty -six-inch (36") diameter culverts equipped with duck bills and slide gates will be constructed to allow high flow temporarily stored in the City basin to drain back into Estudillo Canal. The levee lowering and the installation of the new District drainage structure are independent and will not affect City's maintenance and operation of the existing City basin drainage structures. The District desires an easement for the section of the articulated concrete block mat slope protection that will encroach on the channel outboard side in the City owned basin. Exhibit B shows the boundary of the desired easement area (275'x20' — 5,500 square feet). 4. In order to correct the hydraulic condition at the lateral drainage connection between the Roberts Landing Mitigation Marshes and Estudillo Canal, the District plans to plug and abandon in place the City -owned twin thirty-six inch (36") culverts on the south side of the channel downstream of UPRR, to mitigate tidal flows and to prevent tidal flows from entering Estudillo Canal. 5. Upon the approvals of and authorizations by the City, as provided herein, the District will include the repair of the Monarch Bay Drive Bridge south abutment embankment ("City Bridge Improvements") in the District Project. The City will reimburse the District for any and all actual costs of construction of the City Bridge Improvements, including 15% of actual City construction cost for construction contract administration. The primary anticipated components of the City Bridge Improvements include removal and disposal of existing concrete rubble and placement of rock slope protection. District and City shall implement those activities for which they are each respectively responsible as described in Exhibit C, "Project Implementation" of this Agreement. C. Indemnity Provisions 1. The City agrees to defend, indemnify, and hold harmless the District (with legal counsel reasonably acceptable to the District), the County of Alameda, their governing bodies, their predecessors, successors, assignees, agents, departments, officials, representatives, Page 2 of 6