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Page 44 of 59 <br /> <br />City of Everett Merrill & Ring Bridge Replacement <br />x Perteet will prepare preliminary calculations for flow control and water quality treatment <br />facilities. Budget will be for the design of one (1) flow control facility and one (1) water <br />quality facility. This information will be used during the preliminary bridge Type, Size <br />and Location analysis. Only one of the concepts developed by the bridge designer will be <br />studied from a drainage standpoint. This concept will be mutually agreed upon by the <br />bridge and stormwater designer. <br />x Once a concept has been selected for draft and final design the stormwater flow control <br />and water quality treatment calculations will be updated as necessary for inclusion in the <br />PS&E. <br /> <br />Deliverables: <br />x Preliminary flow control and water quality treatment calculations (to be used for showing <br />Type, Size and Location of the proposed flow control and water quality treatment <br />facilities in support of the preliminary bridge design alternatives analysis. <br />x Draft flow control and water quality treatment calculations (to be included in the Draft <br />Drainage Report) <br />x Final flow control and water quality treatment calculations (to be included in the Final <br />Drainage Report). <br /> <br />12.1.6 Pipe Conveyance Calculations <br />Perteet will prepare storm pipe conveyance capacity calculations for new pipe segments <br />associated with the project site: <br />x Design Development (60%): Prepare preliminary pipe sizing calculations, using full-flow <br />conditions with the Manning equation and the Rational Method. <br />x Final design: Finalize pipe sizing calculations <br />x Gutter flow and sag analysis: Prepare gutter flow and sag analysis (if low point is within <br />project limits) to make sure the flow spread is contained with the roadway shoulders. <br /> <br />Assumptions: <br />x No new outfalls will be needed. The new conveyance system will tie into existing storm <br />drain systems that already lead to existing outfalls. It is further assumed that these <br />existing outfall systems have the capacity to accommodate project flows. <br />x Low infiltration rates and steep slopes make infiltration infeasible and infiltration BMPs <br />will not need to be evaluated as part of the analysis. <br /> <br />Deliverables: <br />x Conveyance Calculations (to be included in the Drainage Report) <br />x Gutter flow analysis (to be included in the Drainage Report) <br /> <br />12.1.7 Drainage Report <br />Perteet will assemble a draft drainage report (60% design phase) and final drainage report (90% <br />design phase). The drainage report will include a written assessment and summary of the surface <br />water design features on the project, summary of tables, flow control and water quality treatment <br />calculations, pipe capacity calculations, drainage basin maps, backwater analysis (Hydraulic <br />Grade Line), and supporting exhibits.