BLD20160875 - Engineering Comments-1.doc
CITY OF EDMONDS
PLAN REVIEW COMMENTS
ENGINEERING DIVISION
(425) 771-0220
City Website: www.edmondswa.gov
DATE: December 13, 2016
TO: Win Lessley
Adair Enterprises, LLC
Adairenterprises1@gmail.com
FROM: JoAnne Zulauf, Engineering Technician
joanne.zulauf@edmondswa.gov
RE: Application #: bld20160875
Project: Nelson - Single Family Residence
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Project Address: 10114 243 Pl SW
During review of the above noted application, it was found that the following information,
corrections, or clarifications are needed. Reviews by other divisions, such as Planning, Building, or
Fire may result in additional comments. Please submit three (3) sets of revised plans/documents with
a response letter addressing each of the items below.
nd
Resubmittals can be made at the Development Services Department on the 2 floor of City Hall.
Permit Center hours are M, T, Th & F from 8am-4:30pm and on Wednesdays from 8:30am-noon.
City of Edmonds handouts, standard details and development code can be referenced on the City
website; edmondswa.gov.
Sheet 1 – Cover/Site Plan
1)Please see #16 below regarding impervious surface calculations.
2)Lot Coverage should not include the roof overhang. Please contact the Planning Division for
more information.
3)Under General Notes: Note #1 Please revise to state 2016 version of WSDOT/APWA standards.
4)Under Public Utility Purveyors, please revise the sewer and water to Olympic View Water and
Sewer District.
5)Under Public Utility Purveyors, please add Storm (City of Edmonds), fire (Fire District One).
6)Under Drawing Index, please remove “prelim”. The site plan should be the proposed
construction.
Sheet 2 – SWPPP and Grading Plan
7)Add inlet protection standard detail E1.3.
8)Please show existing and proposed topos on plan.
9)Add bottom of footing elevations for old home and new construction.
10)Please indicate trees to be removed and add tree protection details to the plan.
11)Grading and fill is noted as 185 cys on this sheet but 150 cys on the SWPP/Grading plan. Please
revise all occurrences to be consistent.
Sheet 3 – Drainage and Utility Plan
Utilities
:
12)Olympic View Water and Sewer District (OVWSD) are the purveyors of water and sewer for
this property. Please provide written confirmation from them stating they have reviewed the
proposal and have no issues with the proposed location of the utilities.
13)Please add COE Utility trench detail E4.2 and E2.3 for road restoration.
14)If the Fire District requires sprinkling in the residence, a larger water meter may be required.
Check with OVWSD.
15)Please revise Utility Note to state “All existing and proposed utilities serving the property will be
placed underground.” This just helps clarify the notes on the plans.
16)Show the location where dry utilities will enter the site and where they will enter the house.
17)Add the following note to plan stating ”All utility separation requirements will be met per
industry standards.”
Stormwater
:
18)The total of the proposed impervious surface is noted to be 4937 sf (.1133 acre) but only 3920.4
(.09 acres) was used in the WWHM modeling. Even if modeling the driveway as landscape (not
completed in WWHM-see 2005 Stormwater Manual, Vol V, Chapter 5, top of page 5-12), there
would be the roofline, 4550 sf (.1045 acre). All new, replaced, or new plus replaced impervious
surfaces are subject to stormwater mitigation requirements per the Edmonds Community
Development Code (ECDC) Chapter 18.30.060 D.2.a,b. Definitions for new and replaced
impervious surfaces can be found in ECDC Chapter 18.30.010. Please make revisions as needed
to provide consistency.
19)Please complete and return the attached Special Inspection Agreement for the “soils
professional” per note on plan to confirm soil type in trench bottom.
20)Invert of pipe shown in the infiltration system detail notes an invert elevation of 371. On plan the
invert is called out at 417.4. Please make revisions as needed.
21)Add note on the plan, that a 10 ft minimum distance is allowed between the south edge of
infiltration trench to south property line.
22)Add invert elevation for tightline connection at house to verify slope to infiltration trench.
23)Note on plan that the transition trench along the driveway is 2 ft in width.
24)Provide sheet dispersion detail-Figure 5.5 from the Stormwater Manual to plans.. Add call out
on plan.
25)Area where gravel is being added with the existing width of driveway exceeds a total width of
20ft. Over 20 ft width of impervious surface using sheet flow requires an additional 5 ft of width
for each additional 20 ft of width or fraction thereof. See BMP T5.12 Sheet Flow Dispersion
Design Guidelines, 2005 Stormwater Manual, Volume V, pg 5-11.
26)Please note the cross slope of the driveway and of the vegetative path.
27)ECDC Chapter 18.30.080.B requires that all sites using low impact development techniques to
ensure that stormwater best management practices continue to function as designed. Please
complete (with black ink) the attached form. The exhibits must comply with Snohomish
County’s requirements for recording documents, see attached. Also attached is an example of an
exhibit. The plan should not be very detailed and be very clear. SnoCo will not record it if there
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is information that is unreadable whether it pertains to the covenant or not. The covenant must
be notarized and approved by the Engineering Division prior to recording at Snohomish County.
Additional charges will occur if it is preferred that the City record the document.
Stormwater Engineer Review:
Reviewer: Robert C. Edwards, PE, Stormwater Engineer, City of Edmonds
Background
This project is the replacement of an existing SFR with a new larger SFR. This is classified as a Category 1
Small Site Project because it creates/adds impervious area more than 2,000 SF and less than 5,000 SF.
Category 1 Small Site Projects are subject to Small Site Minimum Requirements 1, 2, 3, 4, 5, 7, 8, 9, and 11.
Minimum Requirement #1 – Preparation of Stormwater Site Plan
Comments:
1. Sheet 1 The call before you dig number, 800-424-5555 is being phased out. The new number is 811.
profile
2. Sheet 3 The infiltration trench is marked as “Plan View”
3. Sheet 3 The infiltration trench profile indicates the washed rock as 1 ½” -3/4”. This should be 1-1/2”
to 1-3/4”.
4. The 30-foot 6-inch PVC pipe to the infiltration trench needs a minimum slope and/or inverts.
5. The proposed large SFR has only one connection to the infiltration trench. Is this intentional? This will
require a significant downspout collection system to route to a single location.
Minimum Requirement #2 – Construction Stormwater Pollution Plan
Comments:
1. Element #2 Use of an existing driveway in lieu of a stabilized construction entrance is permitted.
However, exiting driveways require frequent inspection and cleaning to limit track out onto the right of
way. Provide inspection frequency and track out remedy.
2. Element #7 An existing CB exists only 30-feet from the proposed infiltration trench. This CB appears
to be at a lower grade than the earth disturbance needed to construct the infiltration trench. Provide
inlet protection for this CB.
3. Element #9 It is not reasonable to expect no outside chemical will be necessary. Consider cover for
storage of chemicals, paints, and fuel. Consider controlling or prohibiting the fueling or maintenance
of equipment on-site.
Minimum Requirement #3 – Source Control of Pollution
Comments: N/A per SFR
Minimum Requirement #4 – Preservation of Natural Drainage Systems
Comments: N/A per LID
Minimum Requirement #5 – Onsite Stormwater Management
Comments:
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1. Drainage Report Page 7, the infiltration trench is described as “6 foot deep” where the plans indicate
24-inch deep.
2. E72D, Requirements For Establishing Design Infiltration Rates:
a. Grain size analysis not provided per USDA method
b. Not plotted on USDA triangle
c. The closest test pit indicates sandy loam to a depth of 27-inches, however the plans indicate a
infiltration trench to only 24-inches. The infiltration trench was not modeled for sandy loam.
3. WWHM Modeling:
a. Rock layer thickness is not provided
b. Rock porosity is not provided
c. WWHM appears to have modeled 100% porous material, IE a vault
d. WWHM model should have raw infiltration rate and safety factor per E72D
Minimum Requirement #7 – Flow Control
Comments: Flow control by LID
Minimum Requirement #8 – Wetland Protection
Comments: N/A
Minimum Requirement #9 – Operation and Maintenance
Comments:
1. The Maintenance Requirements are missing.
a. Consider Table 3.5 of Volume III of the 2005 SWMM for Western Washington,
“Maintenance of Control Structures and Catch Basins.”
b. Consider maintenance criteria for infiltration trenches, page 3-103 of Volume III of the 2005
SWMM for Western Washington.
Minimum Requirement #11 – Financial Liability
Comments: N/A for SFR
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