bld20150490-Sherwood Elem-Paving-Parking-E1.pdf
CITY OF EDMONDS
CIVIL PLAN REVIEW COMMENTS
ENGINEERING DIVISION
(425) 771-0220
City Website: www.edmondswa.gov
DATE:
May 19, 2015
TO:
Thaddeus Egging
thaddeus.egging@kpff.com
FROM:
Jeanie McConnell, Engineering Program Manager
jeanie.mcconnell@edmondswa.gov
Jerry Shuster, Stormwater Program Manager
Bertrand Hauss, City Traffic Engineer
RE:
Application #: bld20150490
Project: Sherwood Elementary
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Project Address: 22901 –106Ave W
During review of the above noted application, it was found that the following information,
corrections, or clarifications are needed. Please redline plans or submit three (3) sets of revised
plans/documents with a written response to each of the items below to a permit coordinator.
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Resubmittals can be made at the Development Services Department on the 2floor of City Hall.
Permit Center hours are M, T, Th & F from 8am-4:30pm and on Wednesdays from 8am-noon.
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Please note, starting June 3, the Permit Center will be closed on Wednesdays.
City of Edmonds handouts, standard details and development code can be referenced on the City
website.
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 and traffic control. Please
use the King County Site Improvement Bond Quantity Worksheet and utilize the “write-in”
sections where appropriate.
A bond is required to be placed forall erosion control measures, right-of-way and
stormwater management improvements. 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.
If you intend to post a bond in order to record the subdivisionand ahead of constructing
required improvements, the bond amount will be based on the entire scope of the project.
Inspection fees for this project will be calculated at 3.3% of the 120% City approved
estimate for all improvements.
2.Include a City Engineering Division approval block on all plan sheets. Refer to sample on City
website.
3.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.” Please note, a ROW permit application with contractor’s
signature shall be provided to the city prior to issuance of civil construction plans.
4.Please provide a traffic control plan for work within City right-of-way.
5.Existing improvements throughout plan set are in a very light font/line type, which makes it
difficult to figure out how the proposed improvements fit in with the existing improvements.
Please darken fine/line type throughout plan set.Pleasenote, anew plan set that was printed in
house at KPFF was delivered to theCity. This submittal is readable –thank you. The cover
memo states “Thisset is not signed as it is intended to supplement the official review
documents”.Future submittals will need to be signed as those plans will become the official
permit set. We are not able to provide project approval based off the plan setthat wassubmitted
with the original permit application.
6.Please note, araingarden covenantwill be required for this project. The covenant will need to
be recorded at Snohomish County prior to final construction approval for project (not prior to
building permit issuance).The City has a template covenant andwill forwardthis soon.
Sheet G0.02 –GENERAL NOTES
1.Update General Construction Notes. Refer to sample on City website.
Sheet C0.01 –MASTER SITE PLAN
1.Please include a project description explaining the proposed layout and intended traffic flow.
Arethere parent only or bus only areas?
Sheet C1.02 –TESC DETAILS
1.Pleasemove construction sequence notes from this detail plan sheetto the TESC plansheet.
Sheet C3.01 –GRADING AND DRAINAGE PLAN
1.Revise sheet title to include “utilities”. See comment under Sheet 4.01 regarding fire hydrant
relocation.
2.Remove storm drain line shown as to be removed on demolition plan.
3.The storm drainage crossing downstream of proposed SDCB #6 has incorrect elevations. Please
revise.
4.Verify that existingSDCB #9 connects to theexisting 18”diameter storm drain. It appears to
be a tee connection. Verify that this is an operational connection.
5.Providean impervious surface area chartconsistent with City handout E72.
6.Please note whether the fire hydrant installation is proposed to be done as a wet/hot tap or cut in.
Sheet C3.02–GRADING AND DRAINAGE DETAILS
1.It is unclear the purpose of Detail 2 on this sheet (very poor quality reproduction as well).
Please note, the quality issue was corrected in thesheets that were submitted to the City May 19,
2015.
2.Detail 2 –Inlets to bioretention/raingardens should have 3-4”of “catch”at theinlet pipe to
collect sediment. Please revise.
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Sheet C3.03–GRADING AND DRAINAGE ENLARGEMENTS AND DETAILS
1.Typical Rain Garden Section:
a.There should be 18inches of bioretention soil mix for treatment not 15”plus the mulch
layer.
b.A geotextile should not be placed under bioretention soil (See LID guidance); they tend
to clog. A solution used by Seattle is Seattle mineral aggregate type26 between the
bioretention soil and the gravel.It is a ¾” washed sandy gravel.See pages 9-11 and 9-
14 in https://www.ecobuilding.org/olympia/flyers-forms/903SR51110Revised.pdf
c.Also, geotextile on the bottom of an infiltration trench tends to clog (top and sides OK).
Sheet C4.01–PAVING AND UTILITY PLAN
1.For clarity, please do not show existing features that were noted for removal on the demolition
plan sheet.
2.Please remove the note that states “sidewalk and ADA curb ramp improvement being
coordinated with 2015 ramp upgrades project”. The school district will be responsiblefor
installation of thisrampin conjunction with theproposed project.
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3.The new sidewalk on 106Ave W couldbe constructed of asphalt to match existing conditions.
Theramp will still need to be constructed of concrete.
a.Revise plans as needed.
b.See notes below under Sheet C7.01 regardingcurb ramp details. The new curb ramp on
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106will need to be modified slightlyto meet ADA standards. A modified detail has
been requested for this ramp.
4.Please provide a detail or explanation of what the center island area is in thelowerparking lot.
A pedestrian island is called out and then a 15-foot aisle (appears to be for traffic?) and then a
walkable pedestrian areasouth of that(at grade?).
5.If the15-foot center aisle is intended for traffic, please show turningmovements can be
achievedwith proposed curb radii at each end of theaisle.
6.Dimensiondrive aisle width between the proposed curb island (at the west end of the proposed
bank of parking stalls in thelower lot)andthe curb radius with C12 reference.
7.Note drive aisle width between the existing sidewalk on thesouth side the building andthe
proposedpedestrian island concrete sidewalk.
8.Provide truncated domes where the crosswalk meets the pedestrianpath on thenorth side of the
15-foot center aisle.
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9.At thesouth end of the 228St accessthe vertical curb is shown to taper down to 1”for a
distance of 12-feet. It appears as though this is for access to thefield via a chain-link gate.
Please add note that clarifies the purpose of the curb drop and reference detail 2 on Sheet L1.02.
Is an asphalt approach proposed in thisarea or will thesurface transition from the curb to lawn?
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10.Show installation of a stop sign, to MUTCD standards,at theaccess to 228St SW.
11.The new fire hydrant location is noted on this plan, but the water main is not shown. Please
move fire hydrant related notes to the grading and drainage (and utility) plan.
12.The constructability of paving what shown on this drawing will be difficult. The amount ofsaw
cutting and sealing just to have so many areas of existing remain pavement seems
unwarranted.The site has more than enough room to manage the stormwater from the areas that
are current plan to remain in place. Sealing so many edges is never 100% andthe long-term
viability of this paving plan is not very good. The site will also look a lot better if less of the
existing pavement remains.
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Sheet C4.02–PAVING DETAILS
1.Please revise sheet number reference for detail1to indicate which plan sheet(s)thisdetail
applies to.
2.Detail 8 –Ramp Paving Enlargement:
a.Will curb be constructed along the perimeter of the path?
b.FYI -The curb ramp wings (R6) are not needed in this instance as the transition on the
sides of theramp is to landscaping instead of concrete sidewalk.
Sheet C5.01–STRIPING AND SIGNAGE PLAN
1.For clarity, please do not show existing features that were noted for removal on the demolition
plan sheet.
2.Indicate signage that will be added to thesite to further direct the flow of traffic through the site.
a.Will there be a designated parent pick-up/drop-off area?
b.Will there be a designated bus loop?
c.Will there be any designatedteacher parking?
d.Will there be any loading/unloading stalls?
3.Signage at pedestriancrossings in high travel areas couldbe beneficial. Please consider.
4.Arethereany one-waydrive aisles in thelower parkinglot? If so, striping and signage should
be added as appropriate.
5.Is the outside loop of thelower parking lot intendedfor one lane of traffic or two?
6.It appears as though a stripe is to be painted on thenorth side of the 15-foot access aisle to
provide pedestrian areaboundary. Please clarify on plans.
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7.Pleaseshow the extension of the existingpainted fogline on 106AveWin the area wherethe
driveway will be removed.
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8.Will the driveway access egress for thesite onto106merge into one lane or will there be two
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lanes all the way to 106?If two lanes, one shall be striped as right only and the other as left
only. If turning movements are restricted then signage shall be added prior to entering the
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queue lanes indicating appropriate lanes to use for south bound 106traffic and north bound
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106traffic.
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9.Add “Do Not Enter”signage at the106egress point.
10.Please confirm that the existing curbramp on the east side of thenew crosswalkin theupper
parking lot meets ADA standards. Show replacement of the ramp as needed.
Sheet C6.01–HORIZONTAL CONTROL TABLES
1.Revise curb ramp table to note which plan sheet details are provided on.
Sheet C7.01–CITY OF EDMONDS DETAILS
1.Detail6–City standard detail E2.16 is not theappropriate detail for the curb ramps R2, R3, R5
and R6.City standard detail E2.17 (or WSDOT equivalent) could be used for rampsR2, R3,
and R6. Ramp R5 couldalso be constructed utilizingdetail E2.17, but amodifieddetail is
requested addressing construction of this ramp as a 4-foot minimum width landing area will
need to be provided at thetop of the ramp connecting all three sidewalk/walkway sections
together.
2.Detail 3 –City standard detail E2.13 –replace with detail E2.12 if asphalt walk is proposed
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along 106instead of concrete.
Sheet C7.02–CITY OF EDMONDS DETAILS
1.Detail 3 –Reference sheet C3.01 instead of C4.01.
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SheetL1.01–LANDSCAPE PLAN
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1.Severaldimensions are provided along theeast side of the access drive connecting to 228St
SW.Please clarify what this represents.
2.Sheet L1.02 indicates installation of a chain link with 20-foot widegate, but this plan sheet
indicates an 8-foot wide gate. Please revise.
STORMWATER REPORT
The following comments areprovided from JerryShuster, Stormwater Engineer. These are
the same comments that were provided via email on May 6, 2015. Please contact Jerry
directly at 425-771-0220 or by email at jerry.shuster@edmondswa.govwith any specific
questions you may have regarding these comments.
Drainage Report, dated April 2015
Provide an exhibit that shows the extent of land disturbing activity for the project.Note that
land disturbing activity is defined as: “Any activity that results in a change in the existing
soil cover (both vegetative and non-vegetative) and/or the existing soil topography. Land
disturbing activities include, but are not limited to clearing, grading, filling, and excavation.
Compaction that is associated with stabilization of structures and road construction shall
also be considered a land disturbing activity. Vegetation maintenance practices, including
landscape maintenance and gardening, are not considered land-disturbing
activity.Stormwater facility maintenance is not considered land disturbing activity if
conducted according to established standards and procedures.” Please review the comment
for plan sheet C4.01 prior to producing this exhibit.
Provide a table with the following information for the post-development scenario:
Area in Acres of Sub-Basin
Surface TypeABCDGrand
Totals
New + Replaced
Impervious
PGIS
Non PGIS
Subtotal
Existing Impervious
(Not Disturbed)
PGIS
Non PGIS
Subtotal
Grand Totals
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The Drainage Report from 1995 when existing sub-basin B was constructed has 1.37 acres
(0.85 acres impervious plus 0.52 acres pervious) going to the existing swale and the
detention facility (available in City files). The Drainage Report for this proposed project has
0.99 acres existing going to theswale/detention. Please reconcile.
Infiltration is the preferred method of stormwater management for the City.Sherwood
Elementary is located in the area of the City that has the best soils for infiltration.Since the
infiltration rate is favorable and the School District has the space, the City would prefer
100% infiltration up to the 50 year event.Note that the City plans to construct an infiltration
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gallery in the summer of 2015 on 228St SW near the proposed entrance to the school to
infiltrate runoff from the adjacent neighborhood.
Per volume V, Section 4.1 of the 2005 Ecology Stormwater Management Manual for
WesternWashington, “If runoff from non-pollution generating surfaces reaches a runoff
treatment BMP, flows from those areas must be included in the sizing calculations for the
facility. Once runoff from non-pollution generating areas is mixed with runoff from
pollution-generating areas, it cannot be separated before treatment.” Rain Gardens 1 & 2 are
modeled for treatment only using the PGIS, when the flows to these facilities insides non-
PGIS. Remodel/resize for the combined flows.
The modeling needs a few modifications to represent what is designed.The bioretention cells (rain
gardens) in Appendix G needs the following changes:
The surface areas of the rain garden needs to be subtracted from the tributary area in the
post-development run.
Bioretention soil porosity should be 40 % per the LID Technical guidance manual.
An underdrain is not present.
Bioretention cells treat runoff by passing it vertically though the bioretention soil mix
(BSM) and infiltrating the water; not filling up the pond and overflowing it to the layer
below.The runs show 0% infiltrated.Add the 2.5 ft of gravel below the BSM and the
design infiltration rate of 1 inch per hour.
A circular riser 12 inches in diameter is modeled.The plan shows the riser is a Type 1 CB
with a beehive grate.
The Infiltration basins modeled in Appendix H needs the following changes:
It does not appear that the MGS Flood model is capable of modeling the proposed
bioretention/infiltration/overflow system.Runoff gets to the infiltration layer by two routes
from the bioretention layer 1) infiltration though the bottom and 2) via the overflow
structure.Please verify that the model accounts for this. If this cannot be accurately
modeled in MGS Flood, WWHM2012 or WWHM4 can do this.
The Bioretention soil Saturated Hydraulic Conductivity should be 1.5 in/hr.
Bioretention soil porosity should be 40 % per the LID Technical guidance manual.
An underdrain is not present.
The infiltration trench does not appear to be a “Trench on Embankment Slope.” Choosing
the “Trench Located Beneath Ditch” option may be more representative.
A circular riser 12 inches in diameter is modeled.The plan shows an 8” pipe (orifice) outlet.
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