2013/04/17 Council Agenda Packet

I Hayes Street CSO Reduction (at SRO I and SRO2) The previous Hayes Street CSO reduction analysis,prepared by consultant and presented to the City in Technical Memorandum,"Hayes Street CSO Reduction",dated April 12,2011,evaluated four alternatives to reduce CSOs at SRO2.The results of this analysis recommended increasing the capacity of the existing conveyance pipe from the Hayes Street SRO2 outfall regulator-structure to the Siphon Headworks. (Refer to Figure 2) Subsequently,to insure the recommended Hayes Street SRO2 improvements provide adequate capacity to convey combined sewer flows when upstream improvements are implemented to reduce CSO overflow at adjacent outfall SRO1,additional hydraulic analysis was requested by the City.This analysis updated the city's hydraulic model and identified potential options to reduce the CSO overflows at outfall SRO1 and verify that the recommended alternative for the Hayes Street combined sewer system is adequate to convey flows to the Water Pollution Control Facility without exceeding the CSO overflows frequency allowed by state law.This analysis and options were presented to the City in Technical Memorandum"SRO1 CSO Reduction Alternatives",dated March 5,2012,which identified four(4)possible solution: 1) stormwater separation,2) detention of combined sewer flows,3)new lift station to handle LS#9 excess flows,and 4)new lift station to handle LS#9 excess flows and future overflows at SRO3. The scope of services in this amendment for the Hayes Street CSO Reduction (at SRO1 and SRO2) Improvements provided for: • • Performing hydraulic analysis,determine alignment options,and develop conceptual design/construction costs for additional alternatives from the Hayes Street SRO2 outfall regulator-structure to the Siphon Headworks,based on the new approach of maximizing the conveyance capacity to the Siphon Headworks. • • Prepare a preliminary design report comprising: 1)preliminary design of the preferred alternative for CSO Reduction Improvements for SRO2,and 2)preliminary design of the CSO Reduction Improvements for SRO1,based on Solution Element#3"new lift station to handle LS#9 excess flows,"identified in technical memorandum dated March 5,2012. • Performing final design and prepare construction documents (plans;specifications,and cost estimates) for bid package"Hayes Street CSO Reduction at SRO2"for improvements between SRO2 outfall regulator-structure and the Siphon Headworks.Services include support for assistance with Public Involvement and Construction Assistance. • Perform additional analyses and support,when requested by the city,relative to overall CSO reduction program for outfalls SRO1 and SRO2 and coordination/data sharing related to the Sewer System Replacement and Capacity Improvements Project 5 otak K\project\31500\31520\Contract\Amend4\AmendFou=\AmendmentFouc021413.doce 6