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PUBLIC WORKS <br /> 2. The comments below were generated from this project's Stormwater Reviewer. If you have any <br /> questions regarding these comments, please contact Jane Zimmerman with the City of Everett <br /> Public Works Department(JZimmerman@u,everettwa:gov). <br /> a. Stormwater Report: <br /> i. The text"24-hr"should be deleted from the storm designation on pages 11 and 12 <br /> —the design storm for determining conveyance capacity is the 25-year recurrence <br /> peak flow, without a storm duration specification. <br /> ii. In the Filterra calculations, type A/B soils are used for the contributing pervious <br /> areas. Type C soils must be used instead, given the geotechnical aspects of the <br /> soils present on the site, unless adequate justification for the use of type A/B soils <br /> are provided. <br /> b. Plans: <br /> i. The plants selected for the Filterra units must meet with the approval of the City's <br /> M&O Division. <br /> ii. Per City standards(see Section 4-2.3(9)),the spacing between catch basins for the <br /> roadway improvements must be reduced. When determining the roadway width <br /> I 4cs ' ✓ to be used in Table 4-2.3(9)B, the sidewalk width must also be included. This <br /> equates to a maximum spacing of 150' between catch basins for the portion of the <br /> 54" pipeline in the paved right of way. The maximum spacing between catch <br /> basins in the non-paved right of way must be 400'to allow for cleaning of the pipe <br /> by City crews. <br /> iii. The runoff from all new and replaced pavement for the Railway Avenue <br /> improvements requatment ane c w M . includes the <br /> Q " . portion of the roadwayires thattre slopes into <br /> theaccord south and doesn't enterThis the 54"pipeline, <br /> for which no treatment is currently shown. <br /> ot(61.4(\fCe-' iv. Stormwater infrastructure was installed in the area,in 2008,by the City to serve <br /> the City's relocated storage yard. This stormwater currently discharges to the <br /> City's combined storm/sanitary sewer system and must not be directed into the <br /> O� new 54' pipe. Any pipes carrying stormwater runoff from east to west across the <br /> improved Railway Avenue shall be either continued to the west side of Railway <br /> Ave when a drainage way exists on the west side of the road, or plugged and <br /> abandoned in place to the east of the improved road section. Please see the <br /> attached as-built drawing for more information. A note should be added to the <br /> plans indicating this requirement. <br /> c. Geotech Report: <br /> i. The geotech appears to be making recommendations based only on the results of <br /> their own, limited investigation, without taking into account other geotechnical <br /> information gathered in the past. However, the depths of the borings for this <br /> particular report terminated at only 11.5' below ground surface, and the ground <br /> surface elevation at the borings isn't given. It's likely that the bottom of the 84" <br /> manholes will be seated on soils below the depth of the borings. The geotechnical <br /> information compiled for the Aspect study indicates the likelihood that floodplain <br /> deposits exist at the depth of the bottom of the manholes. The description of <br /> 1R6-13 �) "floodplain deposits" in the Aspect report is "very soft to medium stiff silt, sandy <br /> silt, organic-rich silt and clay, and peat, interbedded with very loose to medium <br /> _ dense sand to silty sand". <br /> Page 3 of 4 <br />