0583_001.pdf1601 Fifth Avenue, Suite 1600 Seattle, WA98101 206,622.5822 kpff.com
March 4, 2019 1q)ff
Zack Richardson
City of Edmonds Engineering Division
121 5th Avenue North
Edmonds, WA 98020
Subject: 923 Glen St, Edmonds, WA — Project #BLD2018-14-05
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Dear Zack:
Thank you for your review comments dated November 26, 2018. Below is a copy of your comments
along with responses by KPFF in bold.
1. Geotech Report: It is not entirely clear that the site is not suitable for infiltration,
update geotechnical report to:
a. Update boring logs to better explainlidentify the separate soils layers
encountered and where soils become infeasible for infiltration; currently,
the boring logs appear to suggest a uniform profile which does not match
with the restrictive layers described at various depths in the text.
b. Revise text to clarify, explain, and/or describe the cementation observed
and impact on infiltration (ie. why is this not the material which is "typically
suitable for infiltration').
c. Update text to explain/describe why Test Pit 4 (le. southem portion of lot)
was not a viable location for infiltration; current infeasibility justification
focuses on impacts specific to north portion.
4 Please refer to Geotechnical Engineer's Response `19381 — Stormwater Review
Response Letter — Heldridge.pdf'
2. Drainage Report. The report only considers a sub -set of LID features based on
the project being eligible for the direct discharge exemption; however the report
fails to establish that the project meets all of the conditions for a direct discharge
exemption. Update report as needed to clarify how each of the
bullets/requirements of the `applicability' section of SWMMWW 1-2.5.7 (pages 64-65)
are satisfied, and why the project qualifies for the direct discharge exemption.
a. It is understood that the project is under 5, 000 square feet and does not
require flow control/MR #7, however, the project must prove that it qualifies for the
exemption in order to use the reduce LID list (instead of the full List #1); else, the project
shall evaluate the full list #1.
4 The project qualifies for the direct discharge exemption because the project
discharges through the City's MS4 directly Into the Puget Sound, a saltwater
estuary. According to SWMMWW 1-2.5.7, flow control is only required for "projects
that discharge to stormwater directly, or indirectly through a conveyance system,
Into a fresh waterbody." Therefore, the project is not required to achieve the LID
Performance standard, consider bioretention, rain gardens, permeable pavement,
or full dispersion as BMPs.
3. Drainage Report. Update the hatching on the proposed conditions exhibit,
currently, new/replace NPGIS and new/replaced pervious appear to be same
hatch.
4 Hatching updated for clarity.
4. C-Sheets: Include impervious/hard surface areas table with each surface type
listed separately in square feet.
4 Table included.
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Zack Richardson
March 4, 2019
Page 2
5. C-Sheets: Provide or reference details as need for construction of all proposed
site improvements including pavers, plantings, walls, clean-out/drains, etc.
a. Ensure referenced architectural site plans include all details stated on civil
cheat' come of the information rafarencPrt rinP.c nit arttjally anngar to hp
provided on those plans.
4 Gravel and lawn details added.
6. C2. 00. Revise work limits to capture the removed tree area near the middle of
the east property line.
-* Work limits revised.
7. C2.00: Identify areas to received amended soils treatment per BMP T5.13 (ie
work limits) and provide sufficient specifications or details as need for the
contractor to install soils meeting the requirement.
4 Areas to receive amended soils are identified per note 9 (C2.00).
8. C4.00. Tee connections to the public drainage system are not permitted and
required a catch basin; revise plan to provide an appropriately sized CB at the
connection point of to the stone main.
4 Storm connection updated to 6" wye. Catch basin added.
9. C4.00. Provide more grading information and spot elevations at comers of
pavement, high/low points, and walls as needed to demonstrate how the
surfaces will drain.
-* Additional grading and spot elevations provided.
10. C4.00: It appears the proposed contours along the west half of the south property
line are mislabeled; update%orrect as needed and update report to address
impacts from this revised area.
a. Impacts appear to result either from reversing the slope as shown on civil
sheets, or by steepening the slope to the west per architectural site -plan.
Contour labels corrected and updated.
11. C4.00: Show/clarify/add notes as need to demonstrate how the north portion of
roof will drain as proposed. Current roof drain leaders appear too close to
finished grade to reach around the north portion of the structure and may not
account for collection of any roof which does not shed directly to the south or
east edges of structure.
4 Roof drainage shown on sheet A1.3. A note. has been added referencing sheet A1.3.
12. C4.00. Geotech report recommended footing drains for all crawlspace or
basement area; update plan to show extent of proposed footing drains and the
location of footing drain discharge or connection to the system.
-* Foundation drainage plan added to set.
We appreciate all of the assistance that the City Staff are providing for this permit. Please call (206) 622-
5822 with any questions.
Sincerely,
Christopher T. Rapp, PE
Civil Engineer
KPFF, Consulting Engineers Inc.