Eng20160089_Perrinville-1.docx
City of Edmonds
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121 5 AVENUE NORTH • EDMONDS, WA 98020 • (425) 771-0220 FAX(425) 771-0221
Website: www.ci.edmonds.wa.us
PUBLIC WORKS DEPARTMENT
Engineering Division
Plan Review Corrections
Plan Check : Date:
# ENG20160089 April 15, 2016
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Project Name/Address:
Greg Payne Perrinville Drainage 18502 76 Ave W
Contact Person/Address/Fax:
JC McDonnell Engineering John@jcmcdon.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 and Standard Details referred to in these
comments can be accessed at our website: www.edmondswa.gov by choosing the “Services” tab and
“Permits and Development”.
Offsite Drainage Report
Please see the following comments provided by the City’s Stormwater consultants, Herrera.
1.The Offsite Drainage Report (3/4/16) and associated modeling is based on a 25-year, 24-hour event;
however, Minimum Requirement #10 (Offsite Analysis) in the Stormwater Code Supplement to
Edmonds Community Development Code Chapter 18.30 (April 20, 2010) requires sizing conveyance
systems to handle the 50-year recurrence event.
2.Basin 2 lists a density of 8 dwelling units/acre which is inconsistent with a C value of 0.25 used in the
Rational Method model.
3.Basin 2 lengths are inconsistent between the Offsite Drainage Report (3/4/16) and the Rational
Method model:
Offsite Drainage Report Rational Method model
Landscape flowpath 49’ 56’
Pavement flowpath 87’ 90’
4.The following pipe lengths are inconsistent between the Offsite Drainage Plan and the Rational
Method model:
Offsite Drainage Plan Rational Method model
and Schematic
B to A 62’ 65.287’
C to B 32’ 33.2258’
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5.The following pipe inverts are inconsistent between the Offsite Drainage Plan and the Rational
Method model:
Offsite Drainage Plan Rational Method model
and Schematic
Existing CB 264.49’ 264.541’
New CB “A” 264.60’ 264.57’
6.The diameter for Stilling Basin “D” is listed as 48 inches in the Offsite Drainage Report (3/4/16), but
should be added to the Offsite Drainage Plan as well.
7.The pipe length (4’) from New CB “A” to the existing CB is not labeled on the Offsite Drainage Plan
or the Offsite Drainage Schematic.
8.All of the pipe inverts in the New CB “A” are listed at the same elevation (264.60’) in the Offsite
Drainage Plan and the Offsite Drainage Schematic.
9.Typos in the Offsite Drainage Report (3/4/16):
a.Page 3 – “circa 19632”
b.Page 6 – “it is no part” should be changed to “it is now part”
SHEET 1 of 1 OFFSITE DRAINAGE PLAN:
1.Call out sizing for CB’s A, B, and C. If the difference of elevation between the lowest invert and the
rim is 5’ or greater, a minimum 48” manhole is required.
2.Provide a connection to the existing outfall to prevent oversplash and erosion at the turn of the ditch.
3.Add a tesc plan consistent with the requirements of the DOE Stormwater Manual.
4.Show location of existing utilities on site plan.
5.Provide general construction notes.
Please resubmit 3 copies of the revised plans/documents to a Development Services Coordinator. Please
contact me at 425-771-0220 if you have specific questions regarding these plan corrections.
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