bld20080651-Zubair-4.pdf
City of Edmonds
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121 5 AVENUE NORTH • EDMONDS, WA 98020 • (425) 771-0220 FAX(425) 771-0221
PUBLIC WORKS DEPARTMENT Engineering Division
Plan Review Corrections
Plan Check :Date:
#2008-0651 June 15, 2009
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Project Name/Address:
Zubair 22415 100 Ave W Remodel
Contact Person/Address/Fax:
Roger Patten roger@pattenarch.com
Reviewer: JoAnne ZulaufDivision:Engineering
During review of the subject submittal, it was found that the following information, corrections, or
clarifications would need to be addressed. All Handouts referred to in these comments can be accessed at
our website: www.ci.edmonds.wa.us under City Government / Development Services Department /
Engineering Division then scroll down to Handouts:
1.Done.
2.Done.
3.Done
4.07/02/09See Storm Engineers Comments.
STORM WATER ENGINEER REVIEW:
07/02/09 Storm Water Engineer, Jerry Shuster, Comments:
I've reviewed the submittal date June 23, 2009 for Gary A. Flower, PLLC regarding the drainage
requirement for this project and suggestions in a June 15, 2009 correspondence from the City to the
Permittee.
In response to Mr. Flowers comments on our suggestions, I will back up a little a give the project
some context relative to the City's stormwater requirement in Edmonds Community Development
Code 18.30.
This code requires stormwater controls for projects that create 2,000 square feet or more of new
impervious surface. The City has repeated asked for information on the amount of new impervious
surface added since 1977 and has not received a complete answer. As such, it is difficult for us to
know exactly what drainage requirements to require on this property which is further confounded by
the fact that most of work has been completed without records of how some of the features have
been constructed (i.e. infiltration trench and drywell). In addition, without a pre-setting catch basin,
the sand separating the paving stones has a high potential for running off and clogging the on-site
infiltration systems.
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That said, given the site constraints of steep slopes and rockeries, and an assurance by Mr. Flowers
that the existing drainage system will function as intended, the City is willing to accept the most recent
plan as is. This plan includes a new infiltration well trench at the bottom of the new driveway.
04/28/09 Storm Water Engineer Comments
It is unclear from the drawings what the catchment areas are for the two drainage features installed: the drywell and the
infiltration trench. Therefore I can not evaluate their effectiveness at mitigating for the increased impervious surface area,
Also, given the slope of the site, any "overflow" will likely flow towards the existing rock wall located on private property.
While the City does not regulate rockeries on private property, it should be a consideration in the drainage design.
I would like to know where the roof downspout water is going, where the drainage off the patio and concrete/paver
driveway is going (I suspect the later is sheet flowing into the street). Also, to properly evaluate the drywell and infiltration
trench, a soils report is necessary.
CORRECTIONS:
1. Please indicate on site plan where and how the roof downspout water is draining into the system.
2. Please show where the drainage from patio is going. If intended for infiltration trench please show patio drains or
grates making this possible.
3. Show where the water drainage from driveway and parking strip is going.
4. Please provide a soils report.
06/19/09 Engineer’s Comments:
The yard drain proposed at the base of the driveway is too small to provide much
catchment of water drainage from the proposed driveway and parking strip. A majority of the runoff would end up
sheeting over this drain into the street. After visiting your site, our Storm Water Engineer has suggested the following:
1. Place a yard drain at the “low spot” on the south side of the driveway where it tapers to the narrower part of the
driveway. This drain can be connected to and infiltration trench placed between the lower driveway and the rockery.
Trench should be 15 - 20 ft long, 18” deep, 24” wide, lined with geotextile fabric and filler with 1 1/2” to 1 3/4" washed
rock. Connection from yard drain should be 4” perforated pipe. Pipe should have 6” cover measured from base of pipe.
This would catch a majority of the runoff from the upper portion of driveway/parking area.
2. The yard drain proposed at the base of the can still be added to catch the runoff from the remaining area of the
driveway. To ensure that this drain captures the majority of runoff asphalt berms approximately 2” high and 6” wide
should be added to guide water into drain.
Please see attached drawing illustrating these suggestions.
Please resubmit 3 copies of the revised plans/documents to a Development Services Coordinator.
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