Response Letter 20191115_Resub.pdf9740 Evergreen Way * Everett, Washington 98204
WESTERN
ENGINEERS &
SURVEYORS
SURVEYORS • ENGINEERS • LAND USE CONSULTANTS
October 30, 2019
City of Edmonds Engineering Division
Attn: Kernen Lien
121 5t11 Avenue N
Edmonds, WA 98020
425-771-0220
(425) 356-2700
RE: Subdivision File #: PLN20190041, Muresan 3-Lot Short Subdivision
Dear Ms. Lien:
FAX (425) 356-2708
��'��ECEIVE
NOV 15 2019
OL-V t-uPMENT SER\
COUNTER
Below you will find responses to comments in the Letter of Completeness dated August 29, 2019.
Planning Comments:
1. See Memorandum by Nelson Geotechnical Associates, Inc. dated October 24, 2019 for comment
response.
2. Acknowledged. A native vegetation retention area is now shown on the Short Plat map.
3. Acknowledged. Bearings and distance are now shown on all lot lines.
4. Acknowledged. Setbacks have been updated.
5. Acknowledged. The structure has been relabeled as an accessory structure.
6. Acknowledged.
7. Acknowledged.
Fire Marshal Comments:
1. Added 20' private road within 24' tract to front of first home. No Parking -Fire Lane signs called out
for each side of 20' wide road.
2. Callout added for existing fire hydrant location northwest of site. Added notes for evaluation of fire
sprinkler requirements and requirement for Knox entry system if any future gates are proposed.
Stormwater Review Comments:
1. Drainage report and plans have been updated to show all proposed roof drains conveyed to drywells
and all proposed private road and driveway areas conveyed to bioretention cells. Detention pipe
BMPs have been eliminated from the design. A memo from Nelson Geotechnical Associates dated
October 24, 2019 has clarified that groundwater or impermeable horizons are at a significant depth
and there should be no groundwater or impermeable horizons within 5 feet of the proposed
infiltration systems. Also, if drywells and bioretention systems are constructed to penetrate
undocumented fill areas, it appears that full infiltration and bioretention BMPs can be used
throughout most of the site. Bioretention cells are not recommended for areas immediately above
steep slope areas. Road and driveway areas above steep slopes have been designed to be conveyed
to a common bioretention cell within the lower area (NW corner) of the site.
2. A conceptual drywell sizing has been added to the WWHM calculations.
LAND USE CONSULTANTS * CIVIL ENGINEERS * LAND SURVEYORS * ENGINEERING CORPORATION
RAIDS ERVER\2017\171601A EVANS \Engineering\2"1 Civil Plan Response Letter
9740 Evergreen Way * Everett, Washington 98204
WESTERN
NGINEERS &
SURVEYORS
SURVEYORS • ENGINEERS • LAND USE CONSULTANTS
(425) 356-2700 FAX (425) 356-2708
d. The plan has been updated to show conceptual bioretention locations. Permeable pavement
is not recommended due to insufficient Cation Exchange Capacity.
e. Callouts for handling the retrofit roof area have been added to the plan. The ridgeline of the
existing residence runs north to south along the length of the house and it appears 675 sf of
the roof area can be isolated with the installation of a gutter block at a specific distance
along the gutter. The contractor will have to measure the existing roof area to determine the
optimum location(s) for gutter block installation.
MR46 now references the memo by NGA stating that existing on -site soils contain inadequate
Cation Exchange Capacity (CEC) for stormwater treatment. Bioretention areas have been called out
to treat and infiltrate stormwater runoff from proposed private road and driveway areas. Refer to the
drainage report for conceptual bioretention area sizing.
Acknowledged. An exhibit map, Sheet E1, outlining how hardscape areas are handled has been
added to the drawing set.
Per planning comments, a tree retention area comprised of more than 30% of the total property area
is now shown on the plans.
The detention system has been eliminated from the design.
Please let me know if you have any questions regarding this comment response letter or the revised civil
plans, thanks.
Sincerely,
��"�ph��
Timothy Sarkela, P.E.
Project Manager
LAND USE CONSULTANTS * CIVIL ENGINEERS * LAND SURVEYORS * ENGINEERING CORPORATION
RAIDSERVER\2017\171601A EVANS \Engineering\2nd Civil Plan Response Leiter