Moore SP Request for Info-Engr and Storm-E1-PLN20170063.pdfREQUEST FOR ADDITIONAL INFORMATION
Date: February 6, 2018
To: Jen Machuga, Associate Planner
From: Jeanie McConnell, Engineering Program Manager
Subject: PLN20170063, Moore 3-lot short plat
749 —15th Way SW
The comments provided below are based upon review of the preliminary civil plans &
documents for the subject short plat. Additional information is requested from the
applicant at this time in order to continue review of the application and provide preliminary
approval of the short plat. Please ask the applicant to provide a written response to each of
the comments below and revise and resubmit plans accordingly.
1. A 10-foot easement shall be provided along the property frontage for placement of dry
utilities serving the site. All dry utilities shall be brought to the site at a perpendicular
crossing to the site vs. running parallel with the right-of-way as currently shown on the
plans.
2. The existing cleanout in the cul-de-sac shall be replaced with a sewer manhole.
3. Provide approximate invert elevations for sewer at main line connection within City
right-of-way, at property line, and proposed house locations to show feasibility. Call out
length and size of all pipe to verify slopes.
4. Please also address Stormwater Review Comments (attached).
Thank you.
City of Edmonds
STO RM WATE R REVIEW COMMENTS
City of Edmonds
Engineering Division
To: Engineering Reviewer
Date: January 30, 2018
Project Name: 15t" Way
Permit Number: PLN20170063
Address: 749 15t" Way SW
Review Type: Preliminary I ��asibility)
Submittal Date: 2/22/2017
Reviewer: Zack Richardson, PE
City of Edmonds, Stormwater Engineer
Recommendation: I recommend that PLN20170063 be withheld until the comments
below are adequately addressed.
Review Comments:
1. The drainage report does not currently appear to address the impervious
surfaces generated as a result of the required frontage improvements; update
report as needed to address frontage improvement areas.
a. It appears that the frontage and a portion of the site may drain south-west
down 15t" Way; update report to reflect or address apparent additional
basin.
2. Neither the drainage report nor geotechnical report address the fact that two of
the proposed infiltration trenches are proposed within the footprints of existing
improvements which are likely to have significantly varied compaction efforts and
soils strata. Update reports & plans as needed to either:
a. Provide investigation & testing in these areas, OR
b. Provide statement from geotech that they reasonably expect similar
infiltration capabilities in these areas, with supporting argument/evidence
as too why (additional testing will be then be required prior to construction
approval), OR
c. Relocated facilities to more apparently feasible locations.
3. It appears that all infiltration facilities are sized only for the impervious areas and
therefore all pervious areas for the site would shed off toward adjacent
properties. Update plans & reports to either:
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a. Include pervious areas to be collected and routed to infiltration facilities in
the trench sizing calculations, OR
b. Address and/or show impact of runoff from pervious areas toward
adjacent parcels, including impacts from removed or converted vegetation
areas.
i. And show how the driveway system would be isolated from
collecting additional pervious areas.
4. Update geotechnical report to show Ksat calculations and how the infiltration rate
was determined.
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