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Storm gain Master Plan , Phase 2 I RFP No> 1+5-02 .ham... Similar to the SDMP Phase 1, Cost estimates will be performed for the identified most feasible drainage alternatives based on the recommendations in the above tasks and the City concurrence. A preliminary estimated cost of construction will be generated from the quantity estimate using approved unit costs from the City. Unit costs will be based upon the most current cost information for recent similar projects in the area compiled by Michael Baker and approved by the City. The total project costs for each alternative will then be estimated which include line items for project design, survey, geotechnical, administration and construction support. In addition, intangible costs for alternative systems will be investigated, such as environmental mitigation, if these are determined to be critical for a particular system. Major physical constraints will be included in the estimate such as (1) land acquisition, (2) street paving and traffic control, (3) utility relocation or protection, and (4) compliance with the current NPDES MS4 permit. Deliverable; 1. 2015 SDMP Proposed Evaluation Matrix 2. Expected Value Hydrology 3. SD Alternative Summary, Tables and Maps 4. Quantity and Cost Estimate Tables TASK 2B — Alternative LID Improvements Task 2B.1 LID Project Update Based on Task 1.2, Michael Baker will investigate, create, and evaluate an extensive list of potential facilities and methods which will reduce the volume of stormwater runoff and flooding throughout the City. The evaluation will consist of analyzing the feasibility of incorporating LID solutions such as above and below ground detention and retention basins, with the goal of downsizing local facilities and reducing and /or eliminating flooding within City Streets. Along with these larger detention and retention basins, Michael Baker will also evaluate the potential for groundwater recharge through retention and infiltration, stormwater harvest and use for landscape irrigation, as well as impervious surface reduction through green street design. The selection and evaluation process will need to incorporate design strategies that will fit within the requirements outlined in the grant applications to help the City position itself for grant success. Task 26.2 Hydrology Update and Basin Routing Analysis Rational method hydrology will be updated to accommodate the proposed LID facility locations. The hydrology models created in Task 2A will be used to obtain the 10- and, 25 -year storm expected value flow hydrographs for basin routing. Loss rates in accordance with OCHM will be required for the generation of small area hydrographs. Basin routing analysis will be performed to mitigate discharges conveyed in the existing drainage systems. The LID solutions such as detention basin locations as identified in Task 1 will be used for the routing analysis. These storage areas could be traditional detention basins, multi -use recreational facilities, underground storage tanks, etc. Only the expected value 10- and 25 -year storm events will be analyzed. Basin rating curves for each location will be developed based on the area and storage type. Task 26.3 SD System Evaluation Page 1 11 INTERNATIONAL 20C - 25