IECO Comment Response 8.25.16.pdfAugust 18, 2016
JoAnne Zulauf
121 5th Avenue North
Edmonds, WA 98020
(425) 771-0220
Re: Paradise Lane
IECO No. 16-0768
Dear JoAnne,
The project referenced above is revised in response to the review comments dated August 3,
2016. The review comments are numbered on the letter and have been addressed in italics as
follows:
PLAN REVIEW COMMENTS:
Critical Areas Report:
ort:
Thank you for providing the geotechnical report dated May 6, 2016. The subject site contains
and is adjacent to a slope that is steep enough to be considered both a Landslide Hazard Area and
Erosion Hazard Area as defined within the Edmonds Community Development Code (ECDC)
Chapters 23.40 and 23.80. Please provide an addendum to the geotechnical report to address the
minimum setback distance per ECDC 23.80.070.A.1 and the criteria listed in ECDC
23.80.070.A.3 and 23.80.070.A.4.
See new geotechnical report.
Lot Coverage:
Lot coverage is defined as the total ground coverage of all buildings or structures on a site
measured from the outside of external walls or supporting members excluding a maximum of
30" of eaves and decks over 30" in height. The site plan shows a lot coverage area of 2,394
square feet providing lot coverage of 27.4%. This only includes the house and not the attached
deck. Please update the lot coverage calculations to include the deck area.
See revised site plan.
Height Calculations: Please make the following corrections on the site plan and buildings plans:
PO Box 1478 • Everett, WA 98206 • Phone: (425) 303-9363
Fax: (425) 303-9362 • Email:info@insightengineering.net
• A datum point is needed in accordance with the city's height calculation information (see
attached height calculations handout)
• The four corner elevation points need to be established in accordance with the calculation
handout.
• Plan Elevations: Please note that with potential changes in the height calculations on your
site plan you will need to revise the plan elevation sheet (sheet Al) accordingly to match
the updated height information.
See revised site plan. Bench mark has been shown on site plan as datum elevation.
Site Plan:
1. The plot or site plan needs to show the location of all the proposed utilities (i.e.
water/sewer) and stormwater system (infiltration) but does not need to include the details
(length, size, etc.).
All utilities have been shown on the site plan.
2. Please note the distance between the property line and the nearest fire hydrant.
Refer to note #2 on the site plan.
3. Add note to plans "Sidewalk is subject to replacement depending on existing condition or
damage. To be determined by Engineering Inspector on site."
Refer to note #1 on the site plan.
4. Under Impervious surface calcs Proposed Home is noted to have 2394 sf, under Lot
Coverage it is also noted as 2394 sf. Please revise as needed.
The proposed impervious surface area of the home is 2,394 SF. Refer to the revised site
plan. The lot coverage includes home and deck areas.
5. Label infiltration trench.
A drywell is now proposed; a label has been added.
6. Remove clean out note regarding cast iron lamphole cover.
Callout has been removed.
7. Please show the sewer easement on the plan and note easement reference number.
Sewer easement has been shown.
Gradin and "1 E,13'C Plan
PO Box 1478 • Everett, WA 98206 • Phone: (425) 303-9363
Fax: (425) 303-9362 • Email:info@insightengineering.net
There is a mailbox cluster with three boxes in the property frontage over the water
meters. There are no mailboxes on your plans. Revise with whatever the plan is for
them.
The existing mailbox location and water meter will remain and will be used for the
existing home.
9. Temp construction entrance is not shown on the property.
A temporary construction entrance has been shown.
10. Provide top and toe elevation for the northwest end of wall.
The top and toe elevations have been shown.
11. General Notes: Change 2010 WSDOT to 2016.
Update has been made. See sheet C2.
Stor mwater Report Consultant Review Comments:
1. The Infiltration Trench Sizing report (5/16/16) is missing the following information:
a. Project category (Category 1 Small Site Project)
b. Drainage basin/Watershed name
c. Narrative describing how each of the Small Site Minimum Requirements will be
met.
The simplified sizing approach for a drywell has been proposed, refer to the
revised plans and report for more information.
2. The applicant has the option to select the City's Simplified Sizing Approach or perform
continuous modeling. Using the City's Simplified Sizing Approach, a 1.8% sizing factor
would be applied, resulting in a 60 -foot long, 2 -foot wide, and 3 -foot deep infiltration
trench for the 3,356 SF of impervious surface area. The applicant chose to perform
continuous modeling and has proposed a 13.25' x 13.25' x 4' infiltration trench;
however, there are several errors and some additional clarification needed regarding the
proposed modeling approach as summarized below:
a. The WWHM output report (5/11/16) included with the 5/16/16 submittal uses the
Everett Rain Gage with a Precip Scale of 0.80. The Edmonds Stormwater
Supplement requires the use of the Puget East 36 rain gage which can be selected
by checking "Use WS -DOT data" on the "Map Information" tab in WWHM.
See answer to comment #1.
b. The geotechnical report (5/6/16) lists the soils as hydrologic group B; however,
the WWHM output report (5/11/16) lists the soils as hydrologic group C. The
PO Box 1478 • Everett, WA 98206 • Phone: (425) 303-9363
Fax: (425) 303-9362 • Email:info@insightengineering.net
v ..
WWHM output report assumes infiltration through the wetted surface area. Due
to the vertical side slopes, infiltration should be assumed across the trench bottom
only (Use wetted surface area = "no")
See answer to comment 91,
c. The porosity in the aggregate layer was assumed to be 0.4 (or 40%). Typical
aggregate layer porosities (and the porosity used in the simplified sizing tool for
the City) is 0.3 (or 30%).
See answer to comment #1.
d. The proposed infiltration trench does not include an overflow structure. Even
though the trench is designed for 100% infiltration, an overflow structure should
still be accounted for in the modeling approach. Assumptions made for the riser
structure to support the simplified sizing tool for the City included:
i. Riser head = same as height of trench
ii. Riser diameter = 36 inches
iii. Notch height = not applicable
iv. Orifice height/diameter = not applicable
v. Effective total depth = height of trench + 0.1' freeboard for uncontrolled
overflow above the top of the trench
See answer to comment #1.
Please indicate an overflow path on Sheet C2 (Stormwater and Utility Plan, 5/25/16) and
provide justification in the report narrative that runoff above the infiltration trench design
capacity will not cause:
a. Flooding of a building or emergency access
b. Erosion or downstream sedimentation
c. Slope failure
The overflow is approximately 20' from the property boundary. No drainage is
anticipated to leave the site as the site contains soils suitable for infiltration.
4. Note #3 on Sheet C2 (Stormwater and Utility Plan, 5/25/16) should be modified as
follows:
"All disturbed pervious surface areas shall be compost amended per BMP T5.13."
Note #3 has been revised accordingly.
Stormwater and t1tility Plan
12. Add impervious surface calculations to this sheet.
The impervious surface calculations have been added.
PO Box 1478 • Everett, WA 98206 • Phone: (425) 303-9363
Fax: (425) 303-9362 • Email:info@insightengineering.net
,.a.ow..e.e.e. . .. ..:...
13. Proposed deck is not included in the impervious surface calculations. If pervious with
dirt/grass underneath, please add note. If not, add to impervious surface calculations.
See callout..
14. Footing drains are required by the geotech. On the plans they are shown connecting to
the storm system. Please convey to another system or provide a revision to the storm
report showing that the system has capacity to handle them.
The footing drains will be connected to a dispersion trench located on the northern
portion of the site.
15. Where will retaining wall footings be connecting?
The retaining wall footing drains will be connected to the roof drains of the home to be
connected to the drywell.
16. How will runoff be collected from the driveway and sidewalk/stairs be collected and
directed to the infiltration system?
Proposed yard drains will collect the runofffrom the driveway and walkways. Refer to
the revised plans for more information.
17. Add length of storm pipe and an invert at the house and the trench.
Pipe lengths and invert elevations have been provided. Invert at the trench is shown on
detail 2/C2.
18. A 6" grated clean out is called out for the infiltration trench. Is this intentional?
Groundwater is not accounted for in the sizing calculations.
A drywell is now proposed.
19. Infiltration trench detail 2/C2 has 6" of CSBC label pointing to top of trench. Please
clarify the exact area that the crushed should be and note what the remaining 6" should be
compost amended soil if it is to be planted with anything.
N/A. A drywell is now proposed.
20. Water meters are shown as existing on this plan. Call out size of water meter and show
as proposed if there is only a meter box and no meter.
Callout has been shown. Water meter field verified.
PO Box 1478 • Everett, WA 98206 # Phone: (425) 303-9363
Fax: (425) 303-9362 • Email:info@insightengineering.net
21. Add to notes section: Olympic View Water Sewer District is purveyor of water for this
site. Water meter and service location shall be reviewed and approved by OVWSD prior
to construction.
Refer to note #7 on sheet C2.
22. Add sewer easement on this sheet too.
Sewer easement has been shown.
23. Add 6" clean out at edge of easement. This clean out needs the cast iron lamphole cover.
A 6" cleanout has been added at the edge of the easement. Cast iron lamphole cover
callout has been included.
24. The clean out at the house does not require a cast iron lamphole cover.
Comment noted.
25. Call out 6" pipe from main connection to edge of easement. Private service can be 4" or
6".
Callout has been added.
26. Add lengths to each section of pipe.
The lengths of each pipe has been added.
27. Add elevations at main and both the cleanout at the easement edge and at the house to
verify 2% slope.
Invert elevation have been added.
28. Add standard detail for sewer connection.
The standard sewer connection detail has been added.
Please feel free to contact me with any questions or comments you may have.
Sincerely,
Santhosh Moolayil,
PO Box 1478 • Everett, WA 98206 • Phone: (425) 303-9363
Fax: (425) 303-9362 • Email:info@insightengineering.net