bld20110771_Clark_ENG2.pdf
City of EdmondsBLD20110771
TH
121 5AVENUE NORTHEDMONDS, WA 98020 • (425) 771-0220 FAX(425) 771-0221
Website: www.ci.edmonds.wa.us
PUBLIC WORK DEPARTMENT
Planning • Building • Engineering
Engineering Plan Review Comments
PermitApplication:Date:
#BLD2011077112/16/11
th
Project Name/Address:
Clark –1567–9Ave N
Contact Person/Address, Fax or E-mail:
John Fish –johntfish@cox.net
Reviewer: JENNIFERLAMBERTDivision:
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.usunder City Government / Development Services Department /
Engineering Division then scroll down to Handouts:
st
1Review –10/13/11
nd
2Review –12/16/11
1)12/16/11–Comment was not addressed.
10/13/11 Comment: Please add the impervious surface chart as shown below.
LineTypeArea (square feet)
1.Non-Regulated
ExemptRegulated
2.Replaced
3.New (Post 1977)+
Total Regulated Impervious Area
=
4.
Mitigation required if in excess of 2000sf
5.Total Area Mitigated by Existing Stormwater Management System(s)-
=
6.Regulated Area Not Yet Mitigated
=
7.Area Proposed to be Mitigated by Low Impact Development Techniques
=
8.Area Proposed to be Mitigated through Conventional SWM Techniques
DATE E-MAILED12/16/2011PAGE(1)
City of EdmondsBLD20110771
TH
121 5AVENUE NORTHEDMONDS, WA 98020 • (425) 771-0220 FAX(425) 771-0221
Website: www.ci.edmonds.wa.us
PUBLIC WORK DEPARTMENT
Planning • Building • Engineering
Engineering Plan Review Comments
2)12/16/11–Comment was partially addressed.
Per Jerry Shuster, City of Edmonds Stormwater Engineer Program Manager
There are a couple of factors considered during the review:
a) Currently,the developed site is not connected to the City’s storm system. The current
system is an on-site infiltration system.
b) The soils on the site are excellent for infiltration.
Based on the City’s drainage basin map, this site is located in “Puget Sound Piped” drainage
basin. This means that the area connected to the City’s system directly discharges into Puget
Sound via a pipe. The flow control standard for these basins in our Stormwater Supplement
(Table 5-4 for Small Sites) has a flow control standard for the 10 and 100-year event based on the
amount of impervious area (0.25 and 0.45 cfs/acre impervious, respectively). This standard exists
to ensure our current pipe system is not over loaded.
The purpose of a flow control standard is to prevent a flooding and /or erosion problem
downstream on slopes and in creek and lakes and to prevent overflows to our storm system. The
pool is considered new impervious area per our code. Runoff from a full or covered pool and the
surrounding impervious area will likely flowwest over the grassy area towards the tracks and
likely infiltrate into the good soils and not enter the City’s storm system. If a Geotechnical
Engineer verifies that no erosion or flooding problemswill occur downstream (either onsite or
offsite), or that the existing infiltration system will not become overwhelmedfromthepotential
runoff from the pool and the surrounding new impervious by doing a MR#10, offsiteanalysis,
flow control willnot required.
Please provide a report from a licensed Geotechnical Engineer addressing the items discussed
above.
10/13/11 Comment: Per the as-built drawings of the single family, the amount of impervious surface the
onsite storm system was designed for was 11,326 sq ft. However, 13,634 sqft was installed. Per the
engineered system, the existing storm system exceeds the allotted amount. The proposed pool is
showing that 450 sqft of new impervious surface will be added to the lot (pools are considered
impervious).
a.Please show how the surface water runoff will be collected.
b.Please provide engineering calculations showing either:
i.That the existing system can handle the additional surfacewater runoff
ii.A modification to the existing system that allows for the proposed stormwater runoff
DATE E-MAILED12/16/2011PAGE(2)
City of EdmondsBLD20110771
TH
121 5AVENUE NORTHEDMONDS, WA 98020 • (425) 771-0220 FAX(425) 771-0221
Website: www.ci.edmonds.wa.us
PUBLIC WORK DEPARTMENT
Planning • Building • Engineering
Engineering Plan Review Comments
iii.Or a separate system for the proposed surface water runoff.
3)OK
4)12/16/11–Comment was not addressed. It is important that no vehicles and stockpiles are placed
on the infiltration area. Please show a barrier fence to prevent this from occurring.
10/13/11 Comment: Please show barrierfencing around the existing infiltration system.
a.Construction vehicles and stockpiles are not permitted on-top of the infiltration system.
5)12/16/11–Comment was partially addressed. Please add a note on the plans that the soil will be
removed as it is being excavated and will not be stockpiled on site at no time during construction.
10/13/11 Comment: Please show where the stockpiles will be located.
6)OK
7)OK
8)OK
9)OK
10)12/16/11–Comment was partially addressed. The grading calculations need to be shown on the
plans.
10/13/11 Comment: Please provide grading calculations and show bottom of pool elevations.
11)OK
Please resubmit 3 copies of the revised plansand associated documents with a written response to each
item to a Permit Coordinator. Please contact me at 425-771-0220ext 1321or by e-mail at
jennifer.lambert@ci.edmonds.wa.usif you have specific questions regarding these plan corrections.
DATE E-MAILED12/16/2011PAGE(3)