PLN20190017 Complete, need clarification.pdfCITY OF EDMONDS
121 5tn Avenue North, Edmonds WA 98020
Phone: 425.771.0220 • Fax: 425.771.0221 • Web: www.edmondswa.gov
DEVELOPMENT SERVICES DEPARTMENT • PLANNING DIVISION
`ne. I STJ
May 1, 2019
Ihsaan Najib
23804-671" Ave. W
Mountlake Terrace, WA 98043
Subject: COMPLETE APPLICATION, CLARIFICATION REQUESTED —NAJIB 4-LOT SHORT PLAT
AT 7901-240TH ST. SW (PLN20190017)
Dear Mr. Najib:
Thank you for submitting the required documentation and application fees for the above -
referenced permit; your application is complete according to ECDC 20.02.003. However, while
the application is technically complete, additional information or clarification is required.
Please address all comments in a written response and by providing updated plans, as
appropriate:
Engineering and Stormwater comments. Please address the comments from the Engineering
Division dated April 17 and April 30, 2019 (attached).
The City will proceed with the associated public notice requirements. However, please keep in
mind that a complete response to this information request must be received within 90 days
or the application will lapse for lack of information (ECDC 20.02.003.D).
If you have any questions, please contact me at (425) 771-0220.
Sincerely,
Brad Shipley
Associate Planner
MEMORANDUM
REQUEST FOR ADDITIONAL INFORMATION
Date: April 17, 2019
To: Brad Shipley, Planning Division
From: JoAnne Zulauf, Engineering Division
Subject: PLN20190017, Najib 4 lot short plat
7901240th St 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.
GENERAL
1. In accordance with Edmonds Community Development Code (ECDC) Chapter 18.90,
sidewalks are required as a condition of short plat approval. However, sidewalk placement
requirements are now determined by street classification. Due to the classification of this
street, sidewalks are only required on one side of the street. On this stretch of 240tn,
sidewalks have already been established on the other (south) side of the street, therefore
are not required for this development. Please resubmit revised plans.
2. Please confirm that there exists an 11 ft drive lane. If not, road widening will be
necessary.
3. Please complete grading quantities on Sheet C3.0.
UTILITIES
1. Show the location of existing and proposed dry utilities, gas, cable, phone.
2. Provide approximate invert elevations for side sewer at house and property line to show
feasibility. Call out length and size of all pipe to verify slopes.
4. Per the Criteria for Sewage Works Design, Dept of Ecology (aka the Orange Book) states
that a run of 6" sewer line over 150ft can only be approved by DOE review. A manhole
can be installed at some point in the stretch to reduce the run length.
STORMWATER ENGINEER REVIEW
Refer to attached plan review comments by City Stormwater Engineer, Zachary Richardson.
Please contact Zack directly at 425-771-0220 or by email at
zachary.richardson(&edmondswa.gov with any specific questions you may have regarding his
comments.
City of Edmonds
Thank you.
of E°M STO RM WATE R REVIEW COMMENTS
City of Edmonds
Engineering Division
To: Applicant
Date: April 30, 2019
Project Name: Najib 4-lot Short Plat
Permit Number: PLN20190017
Address: 7901 240t" St SW
Review Type: Preliminary
Submittal Date: 4/8/2019
Reviewer: Zack Richardson, PE
City of Edmonds, Stormwater Engineer
Recommendation: I recommend that PLN20190017 be withheld until the comments
below are adequately addressed.
Prior to Preliminary Approval:
1. It is unclear how the standard infiltration rate was established or that the proper
correction factors have been applied; update geotechnical and/or drainage
reports as needed.
a. While the geotechnical report establishes a flow rate for the wells (20
gpm) it is unclear how this was calculated based on both field data and
sieve analysis as stated. Please list the observed/measured in -field rates
and provide the adjusted long-term design infiltration rate separately, and
provide all variables or calculations to convert the two.
b. It is unclear how the rate measured form the well, was converted to a
standard infiltration rate (for a flat surface); show all calculations,
assumptions, and/or variables used to convert the field observed rate to a
standard well rate.
2. It appears that the site to the west, and smaller portion of the site to the north,
may contribute a fair amount of surface runoff to the site; update drainage report
to address run-on, or further explain how these areas were determined to not be
significant contributors of surface water.
a. Ensure planned road and adjacent wall elevations will not create a barrier
to existing flow patterns.
3. The project is within the Halls Creek/Lake Ballinger basin which requires
phosphorus treatment for water quality mitigation; updated report to state that the
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filter product selected at final design will be from the Ecology approved TAPE for
phosphorus treatment (or specify the product type now, and include a copy of the
TAPE approval as appendix to drainage report).
4. It appears that the individual driveways for each home will completely bypass the
water quality treatment; provide additional drain piping to collect and convey
PGIS to the water quality facility and/or address treatment trades as needed.
5. Update the downstream analysis and exhibit to show and better describe a more
realistic surface flow path between the project site and the sub -surface drainage
system; currently it shows the flow going directly through a structure.
6. Identify the planned overflow path for the infiltration system and update text to
address potential impacts of the overflows.
7. It appears that there is an existing speed hump within the project frontage limits;
update plans as needed to reflect the existing speed bump, show that the road
widening shall extend the speed hump (as direct by engineering reviewer), and
ensure drainage is accounted for at the hump location.
8. Update plans and report to address impacts of the concentrated flow at the low
end of the frontage improvements; it appears that the proposed gutter may
concentrate flows onto the adjacent parcel but is difficult to determine.
9. Include with the WWHM report, the output for the peak -flow analysis at POC1
(essentially the flow rate from the bypass area); peak flows must increase less
than 0.1 cfs (0.15 cfs for 15-minute steps) or addition mitigation is required.
10. It should be noted that Ecology has new rules for UIC wells which go into effect
in October of 2019 for any project which has not completed a 30% design effort;
failing to complete a 30% design by October 1, 2019 could result in having to use
the new UIC rules, which include new definitions for which the proposed facility
could be considered a UIC still and which could require a new approach to the
drainage review.
Additional Notes for Civil Design:
The following comments do not need to be addressed prior to preliminary approval, but are provided at
this time to assist the engineer as they revise the design and move toward civil/construction approval.
A. It appears a portion of the on -site driveway, south of the highpoint, will flow to the
frontage and by-pass the infiltration system; this should be corrected and
address accordingly in the final model.
B. The current model uses a 40% void ratio for the infiltration rock which is slightly
above industry average for rock products; engineer shall spec an appropriate
rock product to ensure the 40% void ratio is actually achieved in field (or revise to
30% in the model; all clean rock is assumed to be above 30%).
C. It appears that the filter vault is located in a —10% slope; ensure that a sloped lid
is properly specified and is aligned to be feasible at these slopes.
D. Provide detail of yard drains and ensure that the required riser/control
structure/frop-tee can be installed in the yard drains; at least one riser shall be
provided at the downstream most drain point for each run that inlets to the
infiltration system.
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E. Show remaining contours below 346'; site appears to dip as low as 339 along the
east property line.
F. Provide a detail for the wall along the west property line; identify outlet location of
wall drain and provide details as needed (wall penetrations, etc).
G. Show all cleanouts and inspection ports for the infiltration system in plan view; at
least 1 inspection port will be required (large enough diameter for vactor hose
and all the way to bottom of rock).
H. Show more grading, detail, and/or additional improvements as needed to collect
and convey surface run-off from the panhandle portion of the driveway which
appears to slope away from the only CB currently shown (unclear if filter is CB -
style).
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