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a. Presentation at Everett PWD on 10-14-13 with DeMuth, de Steiguer and King <br />(DK through WEBEX) in attendance. <br />212.3. Revise Alternatives - Utility Bridge and Single HDD only <br />a. Basis for Revisions <br />1. Utility/Pedestrian Bridge - Stormwater pipeline only. <br />2. Single HDD - New HDD will convey SW only. <br />3. Common attributes: <br />a) CSOs will use existing hillside and lower runs of PS01 and <br />PS02. No future extension to KC site. <br />b) SW will discharge only to PS03; with future extension to KC site <br />and deep -water outfall. <br />b. Revise Figures <br />c. Revise Cost Tables. Include life -cycle costs for M&O of each alternative. <br />d. Summarize in brief technical memorandum (7 pages max.) <br />212.4. Modeling Assumptions: <br />a. Expand Phase 1 improvements to eliminate August 29th sewer surcharge <br />where homes reported basement flooding. <br />b. CS based on Phase 1 improvements; 50% disconnection of roof drains. <br />c. CS based on Phase 2 improvements; 50% disconnection of roof drains; plus <br />18% for Climate Change (50-year, 30-minute storm, plus 18%). <br />d. SW based on Phase 2 improvement; 90% disconnection of roof drains; plus <br />18% for Climate Change (50-year, 30-minute storm, plus 18%). <br />e. For the August 29th, 2013 storm event, use the rain gauge data of Rain <br />Gauge 5B (Legion Golf Course); but, prorate the data series based on the <br />maximum intensity of the rain gauge at LS02, which had the greatest intensity <br />for this storm (i.e., pro -ration factor of 3.9 / 3.6 = 1.0833). <br />f. Allow reverse flows from 17th Street Interceptor for both Phase 1 and Phase <br />2, both alternatives. <br />g. Close low -flow connection between SW and CS system for all events. <br />h. Future storm water diversions to KC site or deep -water outfall. <br />i. No CSOs to KC site or deep -water outfall.For Single HDD alternative: <br />1. Keep CS and SW separated. <br />2. For hillside portion, CSOs in existing PS01 and PSO2 <br />3. PS01 and PS02 dedicated to CSOs. <br />4. PS03 dedicated to stormwater. <br />j. For Utility Bridge alternative: <br />1. Storm water only on Utility Bridge <br />2. For hillside portion, CSOs in existing PS01 and PSO2 <br />3. PS01 and PS02 dedicated to CSOs. <br />4. PS03 dedicated to stormwater. <br />212.5. Model Runs <br />a. Test design for each alternative against August 29th Storm for Sewer "M" <br />Phase 1, CS and SW. (3 runs) <br />b. Test design for each alternative against Climate Change values for Sewer "M" <br />Phase 2, CS and SW. (2 runs) <br />c. Determine if surcharging in Grand Avenue will occur and identify options for <br />eliminating surcharge. <br />Version 3 16 4/29/14 <br />138 <br />