Item 21 - Pressure Control Station Relocation and Transmission Main Improvements

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SA-2 Pressure Control Station Relocation and Transmission Main Improvements RFP No. 21-127 SA-2 and generator operational parameters, control conditions including battery storage; Additional piping to connect to Walnut Reservoir and/or distribution system; Preliminary electrical and control system design and operating procedures; Power connection and communication alternatives with Walnut Pump Station; and Site improvements including WQMP and any specific CEQA requirements. Task a: Basis of Dezwyi, Tetra Tech will prepare the Basis of Design report which will summarize all of the alternatives and outline the agreed upon alternative including reasons why the alternative was chosen. The Basis of Design will include 30% drawings of the chosen alternative including proposed site improvements. The nine (9) key design decisions that we identified within our Approach Section (Key Design Decisions) of our proposal will be addressed in addition to the ones noted in the City's RFP. We have assumed that a similar mechanical layout to the SA-7 relocation project and the SA-1 hydro - generator replacement layout will be the starting point for the mechanical layout for the SA-2 facility. Tetra Tech will evaluate the three alternatives for the facility (wall enclosure, building and vault) at the two potential sites (a minimum of six site exhibits). As part of the evaluation, Tetra Tech will recommend any building or perimeter wall architectural features that will help blend in with the local neighborhood surroundings. Noise will be a major factor in the ultimate selection of the alternative. We have assumed for this proposal, that the approved alternative for the facility will be a below ground service vault. Tetra Tech will provide 3D renderings of the service vault to assist the City in its evaluation of the station's operation, maintainability and reparability. Tetra Tech can provide a 3D rendering of OCWD's Injection Well vault structure as the starting point for the vault alternative evaluation. Tetra Tech will evaluate the best method of conveying and connecting the power generated by the hydro -generator to the Walnut Pump Station Facility. In addition, Tetra Tech will recommend the electrical improvements at the Walnut Pump Station Facility and at SA-2 Facility to best use the generated power. Tetra Tech will provide alternative strategies to achieve this goal as well as the feasibility of using the power generated in this manner. This will include possible battery storage units, including size and footprint of said units. With input and assistance from Enterprise Automation, a new Tetra Tech Company, Tetra Tech will work with the City to prepare preliminary electrical and control system design plans and make recommendations for communications between SA-2 and Walnut Pump Station including radio network/ technology options as well as fiber connections. Tetra Tech will perform any hydraulic modeling as required to confirm the benefit of various connection locations to the City's distribution system. Tetra Tech is extremely knowledgeable of the City's water model due to its previous work with ID Modeling (Sedaru) on updating the City's Water Model. Tetra Tech is well aware of the issues working with MWD with regards to modifying any of MWD meter connections (previous experience with the SA-5 Vault Upgrade Project). Tetra Tech's subconsultant, Scott Foster Engineering, Inc., will assist with satisfying MWD's potential request for a transient analysis of the new pressure control station. Scott Foster's scope of work will include: information review; model development under two flow conditions; surge analysis of valve closures, sudden loss of load (runaway) of the hydro -turbine or flow control valve; recommend surge protection measures; and prepare a technical memorandum. TETRA TECH Page 111