IECO Response dated 1.28.16.pdfINSIGHT ENGINEERING M
January 28, 2016
JoAnne Zulauf, Engineering Technician
121 - 5th Avenue North
p
Edmonds, WA 98020
(425) 771-0220 FED 1 u L,_ la
Re: Mueller 4 -lot Short Plat (PLN 20150007)
IECO No. 14-0675
Dear Ms. Zulauf,
The project referenced above is revised in response to the review comments dated November 24,
2015. The review comments are numbered on the letter and have been addressed in italics as
follows:
General
1. Please provide an itemized engineers cost estimate, including units and unit prices, for
both on-site and off-site (right-of-way) improvements, including all utilities, traffic
control, Wetland signage, fencing and restoration. Please use the King County Site
Improvement Bond Quantity Worksheet and utilize the "write-in" sections where
appropriate.
A bond quantity worksheet has been included with this submittal.
A bond is required to be placed for all erosion control measures, right-of-way and
stormwater management improvements. Posting a bond for stormwater systems applies
to subdivisions that involve 7,000 square feet or more of land disturbing activity and as
well as on projects in a critical area or buffer including ESLHA. The amount of the bond
will be based on 120% of the City approved estimate. The City will inform you of the
appropriate bond amount after review of the cost estimate. Please obtain the appropriate
subdivision improvement bond forms from the City.
Comment noted.
If you intend to post a bond in order to record the subdivision, the bond amount will be
based on the entire scope of the project.
Comment noted.
Inspection fees for this project will be calculated at 3.3% of the 120% City approved
estimate for all improvements.
Comment noted.
2. Please submit a traffic control and haul route plan for review and approval,
See Sheet C6 for Traffic Control Plan. A Haul Route Plan will be submitted by the
contractor upon construction plan approval.
3. Add a note to the plans that states: "Approval of these plans does not constitute approval
of the single family residences and associated setbacks. A separate building permit is
required for review and approval of the single family residences.
See Sheet CI under notes,
4. Please add a note to plans stating "A separate right-of-way construction permit is
required for all work within the city right-of-way. A ROW permit application with
contractor's signature shall be provided to the city.
See Sheet C1 under notes.
PLANNING DIVISION COMMENTS
Please find attached review comments from Planning Division reviewer Michael Clugston.
Please contact Michael directly with any questions on his comments. He can be reached via
phone at 425-771-0220 or via email at michael.clugston@edmondswa.gov
Michael's comments have been addressed and a response letter is included with this submittal.
STORM DRAINAGE REPORT
The following comments are provided by Jerry Shuster, Stormwater Engineer in review of the
Storm Drainage Report dated September 30, 2015. Please contact Jerry directly with any
questions you may have on these comments. He can be reached via phone at 425-771-0220 or
via email at gcr °i rCw�lca��dt gv
Stormwater Site Plan for Cas ner SP Se tember ; 11 2015
l agew&„Executive Summary — The second paragraph states that the Custer fine sandy loam soil
are hydrologic soil group (HSG) "C." Volume III or the 2005 Ecology Stormwater Management
PO Box 1478 • Everett, WA 98206 • Phone: (425) 303-9363
Fax: (425) 303-9362 • Email:info@insightengineering.net
Manual for Western Washington (SWMMWW) identifies these soils as HSG "D". Since the vast
majority of the site is this Custer fine sandy loam (as shown in Figure 3), HSG "D" should be
used in all the modeling.
Class "D" soils were used in the revised stromwater calculations. Refer to the revised drainage
report.
1'Ye `l, Executive SUM111ar + — The third paragraph states that the project is subject to minimum
requirements (MR) #1 -9. The site is subject to MR # 1-11.
All minimum requirements have been applied to the project.
[)a,e 5 -- Since the project has 1.09 acres of land disturbing activity, it classifies as a Large Site
Project. The project is subject to all the MRs in Chapter 4 of the Edmonds Stormwater Code
Supplement and the 2005 the SWMMWW.
The project has been referenced as a Large Site Project. Please refer to the revised drainage
report.
MR #1 - The City currently uses the 2005 SWMMWW and not the 2012
SWMMWW.
The drainage report has been revised to follow the 2005 SWMMWW. Please refer to the revised
drainage report.
MR #6 - The report should state whether the project creates 5,000 SF or more of
pollution generating impervious surface area. If it does, use Chapter 2, Volume V of
the 2005 SWMMWW for choosing the proper treatment approach.
The total PGIS for the site is 10,334 SF which is greater than 5, 000 SF. Therefore
water quality measures must be applied to all PGIS Rain gardens (bioretetion) will
meet the water quality requirement for the site per DOE specifications. The rain
gardens will treat the polluted runoff through absorption and infiltration through the
designated bioretention soils and vegetation.
MR# 8 - The document should address the requirements for this MR found in
Volume I, Section 2.5.8 of the 2005 SWMMWW.
All onsite PGIS will be infiltrated and treated through the onsite rain gardens,
therefore the wetlands and stream downstream of the site should experience no
polluted runoff due to the proposed development.
'a_ge - Add MR's # 10 & 11. Note: Section 3 "Offsite Analysis" meets MR#10.
PO Box 1478 • Everett, WA 98206 • Phone: (425) 303-9363
Fax: (425) 303-9362 • Email:info@insightengineering.net
MR 's # 10 & I 1 have added.
J'a, e — Last paragraph. See Comment for Page 3, Executive Summary, second paragraph.
All minimum requirements have been addressed.
Page 16, last lr�,ga ra h —
See Comment for Page 3, Executive Summary, third paragraph.
All minimum requirements have been addressed.
0 The rain gardens cannot be sized using the Category 1 Small Site requirements, this is a
Large Site Project.
The rain garden have been sized by using WWHM 2012 (Western Washington Hydrology
Model).
1 ag i 7 Sectl t S.tl - See Comment for Page 3, Executive Summary, second paragraph.
All minimum requirements have been addressed.
Rain Garden sizin
The geotechnical report does not contain all the site characterization criteria found in Volume III,
Section 3.3 of the SWMMWW. The design infiltration rate used in the modeling is from two
Test pit sample. The location and depth of theses test pits as well as the grain size distribution
are not included on the submittal. For design purposes, soil samples must be collected at the
location of the proposed bioretention/rain gardens at or below the proposed depth of the native
soil bioretention soil interface.
Also, volume II, Section 7.7.2 of the 2005 Ecology Manual states:
• A minimum of 3 feet of clearance is necessary between the lowest elevation of the
bioretention soil, or any underlying gravel layer, and the seasonal high groundwater
elevation or other impermeable layer if the area tributary to the rain garden meets or
exceeds any of the following limitations:
0 5,000 square feet of pollution -generating impervious surface; or
0 10,000 square feet of impervious area; or
o 3/4 acres of lawn and landscape.
• If the tributary area to an individual rain garden does not exceed the areal limitations
above, a minimum of 1 foot of clearance is adequate between the lowest elevation of the
PO Box 1478 • Everett, WA 98206 • Phone: (425) 303-9363
Fax: (425) 303-9362 • Email:info@insightengineering.net
�.__m....�__.. _.._...� ___ —�...... �..._._�
bioretention soil (or any underlying gravel layer) and the seasonal high groundwater
elevation or other impermeable layer.
Based on these comments, the submittal is deemed incomplete and no addition review time will
be incurred by the Stormwater Engineer until at least the aforementioned comments are
adequately addressed (Plans were not reviewed).
The rain garden have been sized by using WWHM2012 (Western Washington Hydrology
Model). Please refer to the revised hydraulic calculations. A geotechnical recommendations
letter has been included with this submittal.
SHEET x of x — TRAFFIC CONTROL PLAN
Please provide traffic control plan.
See Sheet C6
SHEET C1.0 — COVER SHEET
1. Add reference to City subdivision file number, PLN20150007.
Added to all Sheets.
2. The preliminary conditions are really meant as kind of a checklist of things to be included in
the next stages of the process and not needed on this sheet.
Conditions have been removed.
3. Please add General Notes to the plans, an example is available on the City website.
General Notes have been revised.
4. Please add to notes that drainage for Tract A, and the access easement across Lots 1 and 4
will be installed with the subdivision.
Refer to Note #41 under general notes.
5. Add address of short plat to the plan sheet in the box above Utilities.
Done.
6. As noted in the Engineering Conditions of Approval matrix:
PO Box 1478 • Everett, WA 98206 • Phone: (425) 303-9363
Fax: (425) 303-9362 • Email:info@insightengineering.net
a. (2a) Please show how entrance meets geometrics for 25 mph speed posting. Provide a
detail of the area. Include mailboxes, address signs and any other appurtances found
or proposed at Caspers.
All existing appurtances have been shown on the revised plan. These include the
sidewalk and mailboxes. We are using the existing driveway to access the project and
existing conditions will not be affected. We have also removed the proposed sidewalk
from our plans.
b. (2b) Paved portion of access road shall be 20 ft in width, an 18 ft width is shown on
the plans. There is a possibility that the paved area could be reduced once past the
driveway of 307 though that would depend on the fire departments requirements.
Revised the plans to show 20 ft stamped concrete.
c. (2d) Show sidewalk ramps on both sides of the access. Add note "Driveway ramps
shall meet ADA requirements."
Since there is no sidewalk -proposed, this comment does not apply.
d. (3c) Show driveway entrance on each lot.
See revised plans.
e. (5a) Show all easements and label. Please show all the easements on this sheet
including utility easements.
All easements are shown and labelled.
7. Please revise signature box to state "City Engineering Division" instead of "Public Works"
See revised plans.
SHEET C-1.1— EXISTING CONDITIONS PLAN
8. Please add "Tree Removal" to the title of this sheet.
Done.
9. Please revise the limits of clearing and tree removal to only include the areas that will be
disturbed with the short plat improvement construction.
Refer to Sheet C2.0 for revised limits of clearing.
PO Box 1478 • Everett, WA 98206 • Phone: (425) 303-9363
Fax: (425) 303-9362 • Email:info@insightengineering.net
......... ._
10. Please add a tree protection standard detail to Sheet C2.1 and add a reference to it in the
Notes on sheet C 1.1. Revise other Tree Protection Notes as necessary.
Refer to Note #7 on Sheet C1.I
11. Add signature approval box.
Done.
SHEET C-2.0 — GRADING AND TESC PLAN
12. Please revise the limits of clearing to only include the areas that will be disturbed with the
short plat improvement construction. Relocate tesc pond as necessary to reduce disturbance.
See revised plan.
13. Please add note to plans: Orange barrier fence and/or orange silt fence shall be added around
each proposed rain garden to prevent compaction. Add call outs to plans.
See revised plan and Note #2.
14. Add Grading Cut and Fill quantities to this sheet
Grading quantities are shown.
15. Silt fence is shown in front of 307 Caspers driveway. Please revise.
Silt fence has been removed there.
16. If possible, please consider using less invasive tesc measures where effective.
See revised plans.
17. Show saw cut area in asphalt needed to install water lines to main.
Done.
SHEET C3.0 — ROAD DRAINAGE AND UTILITY PLAN
Storm:
18. Impervious Areas chart: Please revise impervious surface to add Tract A separately and
assign the impervious surface of access road over Lots 1 and 4 to those lots respectively..
Tract A is shown separately. Lots I and 4 impervious area include access road impervious.
PO Box 1478 • Everett, WA 98206 • Phone: (425) 303-9363
Fax: (425) 303-9362 • Email:info@insightengineering.net
19. Separately, add a Short Plat Impervious chart that notes only the impervious surface to be
constructed with the short plat and identifies the mitigation point for the runoff.
Please refer to the Table on sheet C3.0 showing the impervious areas and mitigation
measures.
20. Show driveway approach to each lot to be constructed with the short plat improvements.
See revised plans.
21. Please add a proposed a house outline and driveway on each lot. Call out impervious surface
for each and show the rain garden sized to meet the proposed impervious.
See revised plans.
22. The lot rain gardens will not be part of the approved construction for this permit. Please
change line type, maybe just show the outer circle without the callout so it is clear they are
not part of the short plat construction. The outfall connections will need to be installed with
the short plat improvements so please show those in the heavier line with the invert at the
rain garden and at the connection to the main outfall pipe.
Refer to Note# 3.
23. It is unclear how the runoff from the access road crossing Lots 1 and 4 will be captured and
mitigated. Final grade on sheet C2.0 shows that section is sloped to the east. CB#1 is not
directed to mitigation and therefore should have a solid lid called out so it does not collect
any runoff. Please revise plan to show the mitigation point etc.
Access road area will be graded to drain directly to the rain gardens on Lots I and 4. CB41
has been revised with solid lid.
24. Add a drainage easement across Lot 3. Show all easements on sheet C1.0, it's just easier to
read on that sheet.
Drainage easement has been added and shown on Sheet Cl.
Sewer:
25. City sewer main is difficult to see on plans. Please add callout or label to identify it clearly.
See revised plan.
26. ***1 am waiting on the sewer division to hear how they would like you to connect to main. I
will forward info as soon as I receive it.
Comment noted. This proposed side sewer was approved and looked by them in the
preliminary.
PO Box 1478 • Everett, WA 98206 • Phone: (425) 303-9363
Fax: (425) 303-9362 • Email:info@insightengineering.net
27. Provide invert elevation at connection to sewer main to confirm 2% slope.
Done,
Water:
28. Water meters shall be located within the City right-of-way at back of sidewalk. It is unclear
without the sidewalk called out if they are behind it or not. Please revise.
See revised plans
29. Call out water stubs at each property. Please provide 10 ft separation between the water and
sewer stub outs.
Done„
30. For fire sprinkling, the fire division requires 1 %2" water lines in most cases. Please revise
plans or discuss with the Fire Marshall reviewing this project.
1-112 inch poly is proposed.
31. Add note to plans "Contractor shall be responsible for restoration of trenches required for
installation of water lines."
See note 91,.
Road:
32. Revise road width to meet engineering requirements as noted in comment #6b.
Done
33. FYI: Sidewalk along access drive is not a City requirement.
Sidewalk has been removed and the access road section has been changed to stamped
concrete.
34. Driveway entrance to meet current ADA requirements at frontage. Add note.
See Note#2
35. Provide top of wall and bottom of wall elevations at each end of the proposed wall.
Done.
SHEET C3.1— RAINGARDEN PLAN AND DETAILS
PO Box 1478 • Everett, WA 98206 • Phone: (425) 303-9363
Fax: (425) 303-9362 • Email:info@insightengineering.net
_"_11""'_"'_'_'__'_'_ _ _ ..... .... _.d_. _.._ ,.,
36. Storm report states on pg. 3 that a separation is necessary between the bottom layer of the
rain garden and the groundwater level at 3ft below grade. The current design does not allow
for any separation between the bottom and the groundwater level.
The required minimum separation from the bottom of the rain gardens and the high-water
elevation is 1 ft. Please refer to the revised geotechnical recommendation letter that states
that the high-water elevation is 4 ft below the existing grade. With the total depth of the rain
gardens are 3 -ft, therefore the ]-ft minimum separation from the bottom of the rain garden
and the high-water elevation will be met.
37. Rain garden #5 shows roof drains connection. Revise to show road drainage connection.
The road drainage connection is shown.
38. Revise drainage structure sizing to meet Large Site requirements.
The rain gardens have been sized by using WWHM 2012 (Western Washington Hydrology
Model) to meet the Large Site requirements. Please refer to the revised hydraulic
calculations and the sheet C3.1 for more details.
39. Please note amount of impervious surface each rain garden in designed to mitigate.
Please refer to the Table on sheet C3.0 showing the impervious areas and mitigation
measures.
40. Please revise notes on this sheet as needed for sequence and applicability.
The notes have been revised.
SHEET C4.0 and C4.1— NO'T'ES AND DETAILS
41. Revise sheet to contain all standard details that are relevant to this plan set and remove those
that are not. Please review the City standard details on the City website and add all that
apply. If hydrant detail is there to reference the storz adapter, please add note to that effect or
maybe just remove it and add a note to Sheet C3.0 to avoid any confusion.
Done.
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