PLN20180057_Request for Additional Info.pdfCITY OF EDMONDS
121 5th Avenue North, Edmonds WA 98020
Phone: 425.771.0220 • Fax: 425.771.0221 • Web: www.edmondswa.gov
DEVELOPMENT SERVICES DEPARTMENT • PLANNING DIVISION
I/Jc. ]89v
December 12, 2018
Donna Breske
21 Avenue A, Suite 4
Snohomish, WA 98290
donnab@donnabreske.com
Subject: Request for Additional Information
Groset Two -Lot Short Plat
File number PLN20180057
Dear Mr. Groset,
The City of Edmonds has reviewed the November 27, 2018 resubmittal materials for the Groset
two -lot short plat located at 22027 — 96th Avenue West and it was found that the following
information, correction or clarifications need to be addressed before review of the application
may continue. The numbered items below are from the October 4, 2018 letter of
incompleteness and request for additional information. New comments are in red. Please
respond to the following:
1. - 4. All completeness issues have been addressed and a letter of completeness was issued
on November 28, 2018.
In addition to the completeness issues above, during review of the application it was found that
the following information, corrections, or clarifications also need to be addressed.
5. Please respond to the comments from JoAnne Zulauf, Engineering Technician, provided in
the attached memorandum. If you have any questions on Ms. Zulauf's comments, you may
contact her at (425) 771-0220 or JoAnne.Zulauf@edmondswa.gov.
All comments except for comments regarding storm water were addressed. While a
drainage report was provided with the November 27, 2018 resubmittal as requested, the
storm water engineer had some comments on the drainage report. Please respond to the
attached comments regarding the drainage report.
6. Addressed.
7. Please refer to ECDC 20.75.060 for all required information to be shown on the preliminary
plans and have your surveyor revise the plans as necessary to meet these requirements. As
part of your surveyor's revisions to the plans, please ensure the following items are
addressed:
Indicate the locations of all existing structures and the locations of all existing structures
within 25 feet of the proposed subdivision.
While structures on the adjacent properties was added to the preliminary short plat, it
appears a couple of structures on the subject property were not identified. These
structures are highlighted in red below. These structures will have to be demolished or
removed prior to the short plat being finaled. Please identify all structures on the
subject property.
8. Addressed.
9. Addressed.
Please note that the application will be placed on hold until a response is received regarding the
above items. According to ECDC 20.02.003.1), the above requested information must be
submitted within 90 days (or by March 12, 2019) or the application will expire.
If you have any questions, please contact me at 425-771-0220 or via email at
kernen.lien@edmondswa.gov.
fncerely,
ernen Lien
Environmental Programs Manager
Cc: Ola Groset
MEMORANDUM
REQUEST FOR ADDITIONAL INFORMATION
Date: December 10, 2018
To: Kernen Lien, Planning
From: JoAnne Zulauf, Engineering
Subject: PLN20180057, Groset 2 lot short plat
22027 96th Ave West
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.
Stormwater Engineer Review Comments:
1. Geotechnical Report: It is not clear that the required correction factors were
applied to the measured infiltration rate to obtain the long-term design
infiltration rate; provide or show calculation for converting between the two
rates using the required correction factors (copied below).
Ksatdzs,b„ = Ksat,,,;u,i x CFI• x CFr x CF„
Table B.1. Correction Factors to be Used With In -Situ Saturated Hydraulic Conductivity
Measurements to Estimate Design Rates.
Issue
Partial Correction Factor
Site variability and number of locations tested (CF)
CF = 0.33 to 1.0
Test Method (CFT)
CFT
• Large-scale PIT
• CFT = 0.75 for Large-scale PIT
• Small-scale PIT
• CFT = O.S for Small-scale PIT
• Other small-scale (e.g., Double ring, falling head)
• CFT = 0.4 for other small-scale test
• Grain Size Method
• CFT = 0.4 for Grain Size Method
Degree of influent control to prevent siltation and bio-buildupCFna
= 0.9
2. Drainage Report: Paragraph 3 of the executive summary appears to have
some errant text stating full infiltration is not feasible due to flow paths; clean-
up and clarify as needed.
3. Drainage Report: Report states several times that site will be designed to
infiltrate 100%; however, there appears to be a by-pass area of driveway
City of Edmonds
proposed which will discharge surface runoff without mitigation. Update text
and downstream analysis as needed.
4. Drainage Report: Update MR #5 section to state how the proposed bypass
area satisfies MR #5, and/or provide mitigation BMPs as required.
5. Drainage Report: It does not appear that the `retro-fit' requirement of ECDC
18.30.060.D.5.b.i has been addressed; update plans and report as needed to
provide mitigation for 25% of the existing unmitigated surfaces to remain.
6. Sheet 1: List the vertical datum used for the topo/design.
a. Note: Listed elevations vary rather significantly (15'+) from the City
contours; engineer shall verify all elevations were translated to the
project datum correctly.
7. Sheet 2: Show a storm stub for collection of the roof runoff from the shop
building and/or clarify how the structure will drain to the rain garden.
8. Sheet 2: It appears that the proposed drywells for footing drains do not comply
with setback requirements for infiltration facilities; updated as needed to
maintain required setbacks.
9. Sheet 2: While the rain garden detail has a dimension and label for 6"
freeboard, it appears the south -side (left side of detail) does not actually come
up high enough to provide 6" freeboard as shown; update as needed to
provide required 6" freeboard.
a. Note: The model appears to have assumed a 6" ponding depth but a
12" ponding depth is currently shown; it may be that elevations internal
to the rain garden need adjustment without adjusting the grading.
Please contact Zack Richardson, Stormwater Engineer, directly with any comments
or questions at 425-771-0220.
Thank you.