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Wet Weather Flow Management Program Evaluation of Alternatives for Parallel Granada Force Main and Wet Weather Storage Facilities. Sewer Authority Mid-Coast Side Board Meeting. June 25, 2007. Presentation Outline. Purpose of study. Purpose of study. Confirmation of Whitley Burchett study.
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Wet Weather Flow Management ProgramEvaluation of Alternatives for Parallel Granada Force Main and Wet Weather Storage Facilities Sewer Authority Mid-Coast Side Board Meeting June 25, 2007
Presentation Outline • Purpose of study • Purpose of study • Confirmation of Whitley Burchett study • Confirmation of Whitley Burchett study • Four alternatives • Four alternatives • Recommended project • Recommended project • Comparison to alternatives for single Granada force main
Purpose of Study • Confirm recommendations of WBA study of parallel force main • Confirm recommendation of WBA study of parallel force main • Update hydraulic model • Update hydraulic model • Evaluate alternatives for dual force main approach
WBA Study • Results agree with updated hydraulic model • Results agree with updated hydraulic model • Will assume PVC for force main • Will assume PVC for force main • Gravity section downstream of force main limits flow – but no improvements required
Hydraulic Model Update - Results • Minor adjustments to controls can be made to Montara Pump Station to limit flow to Portola Pump Station • Minor adjustments to controls can be made to Montara Pump Station to limit flow to Portola Pump Station • Hydraulic capacity of parallel force main + gravity sewer is 7.1 mgd • Hydraulic capacity of parallel force main + gravity sewer is 7.1 mgd • Gravity sewer is limiting factor
Storage at Portola Pump Station Not Needed If: • Replace pumps to provide 7.1 mgd • Replace pumps to provide 7.1 mgd • Add parallel, 14-inch force main • Add parallel, 14-inch force main • Raise junction box 2 walls • Raise junction box 2 walls • Add storage volume of 130,000 gal at WWTF
Buried large diameter storage pipes (length is 500’ each) Portola Pump Station IPS Pipeline
Wastewater Treatment Facility Overflow/Storage Facilities Storage Basin (Converted Aeration Basin 4)
Cost Comparison – Dual Force Main versus Single Force Main(1) • Including project cost and contingencies. • Taken from 1/20/05 Project Memorandum to SAM, adjusted for current Engineering ENR + 25% correction for construction market.