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bld20080651-Zubair-3.pdf City of Edmonds TH 121 5 AVENUE NORTH • EDMONDS, WA 98020 • (425) 771-0220 FAX(425) 771-0221 PUBLIC WORKS DEPARTMENT Engineering Division Plan Review Corrections Plan Check :Date: #2008-0651 June 15, 2009 th Project Name/Address: Zubair 22415 100 Ave W Remodel Contact Person/Address/Fax: Roger Patten roger@pattenarch.com Reviewer: JoAnne ZulaufDivision:Engineering During review of the subject submittal, it was found that the following information, corrections, or clarifications would need to be addressed. All Handouts referred to in these comments can be accessed at our website: www.ci.edmonds.wa.us under City Government / Development Services Department / Engineering Division then scroll down to Handouts: The following issues were not addressed on your resubmittal: 1.Done. 2.Done. 06/15/09 Still Not Done 3.. 4/28/09 Not done. Per City of Edmonds Community Development Code, driveways are not permitted over 14% slope. A written request to the City Engineer can be submitted for a slope waiver up to 20%. Please submit a letter to the City Engineer requesting a slope waiver. Include in detail why maximum slope can not be met. Your reason can be that the grade of the existing garage and the grade of the existing road make it impossible to attain a slope under 14% 06/19/09 See Storm Engineers Comments 4.. Due to an increase of replaced and new impervious surface over 2000sf, a storm engineer review was required.Please review engineer’s comments below and respond to corrections. STORM WATER ENGINEER REVIEW: 06/19/09 See Engineers comments below .It is unclear from the drawings what the catchment areas are for the two drainage features installed: the drywell and the infiltration trench. Therefore I can not evaluate their effectiveness at mitigating for the increased impervious surface area, Also, given the slope of the site, any "overflow" will likely flow towards the existing rock wall located on private property. While the City does not regulate rockeries on private property, it should be a consideration in the drainage design. I would like to know where the roof downspout water is going, where the drainage off the patio and concrete/paver driveway is going (I suspect the later is sheet flowing into the street). Also, to properly evaluate the drywell and infiltration trench, a soils report is necessary. CORRECTIONS: 1. Please indicate on site plan where and how the roof downspout water is draining into the system. 2. Please show where the drainage from patio is going. If intended for infiltration trench please show patio drains or grates making this possible. 3. Show where the water drainage from driveway and parking strip is going. 4. Please provide a soils report. DATE FAXED/E-MAILED 6/22/2009 PAGE __1__ OF __1_ 06/19/09 Engineer’s Comments: The yard drain proposed at the base of the driveway is too small to provide much catchment of water drainage from the proposed driveway and parking strip. A majority of the runoff would end up sheeting over this drain into the street. After visiting your site, our Storm Water Engineer has suggested the following: 1. Place a yard drain at the “low spot” on the south side of the driveway where it tapers to the narrower part of the driveway. This drain can be connected to and infiltration trench placed between the lower driveway and the rockery. Trench should be 15 - 20 ft long, 18” deep, 24” wide, lined with geotextile fabric and filler with 1 1/2” to 1 3/4" washed rock. Connection from yard drain should be 4” perforated pipe. Pipe should have 6” cover measured from base of pipe. This would catch a majority of the runoff from the upper portion of driveway/parking area. 2. The yard drain proposed at the base of the can still be added to catch the runoff from the remaining area of the driveway. To ensure that this drain captures the majority of runoff asphalt berms approximately 2” high and 6” wide should be added to guide water into drain. Please see attached drawing illustrating these suggestions. Please resubmit 3 copies of the revised plans/documents to a Development Services Coordinator. DATE FAXED/E-MAILED 6/22/2009 PAGE __1__ OF __1_