20101115170358469.pdfWA 98020 - (425) 771-0220 FAX(425) 771-0221
Website: ww\v,ci.c&ioiids,wa.us
Plan Check #: BLD20100757 Date, November 15, 2010
Project Name/Addres,s- Clearwater SFR 22806 96"' PI W
Contact Person/Addressffax: Tom Berg tomberg58,@yahoo.com
Reviewer: JoAnne Zulauf Division: EngineeKing
During review of the subject submittal, it was found that the following information, corrections, or
clarifications would need to be addressed. All Handouts and Standard Details referred to in these
comments can be accessed at our website. wwiv.c.Ledmonds.waus by clicking City Government / City
Department / Public Works / Engineering Division -
Please N'ote. Building Handouts (10 not haeltide tqxhilted Erigincering Division 11equirenierats. Refer to
Engineerhig Handouts for all Engineering Requiretneiiits.
Drainage plan will not be reviewed by the Storinwater jEMincer as submitted. See comments under
Stormwater Mit
.0---igaili —01-1.
General:
1. Is a retaining wall planned for this property? If so, please show on plans and note bottom of
wall (bow) and top of wall (tow) elevations at each end and for every two feet of change.
2. Add note to plans- "Replacement is required of any plat improvements that are damaged
during construction."
3. Show dimensions of structure, deck, driveway length and width at road and property line.
4. Note on plan: "See, Gradiing/TESC and Drainage/Utility Plans for more information,"
5Please add site address and tax id number to site plan information. Add the identifying plan
information shown on the site plan to the grading/erosion plan and the drainage utility plan.
6. All civil plans have note "See General Notes". I cannot locate the notes to which you are
referring. Please add a general notes section to the civils. Attached is an example though
may contain more or less requirements than are required for this project as it is only an
example.
DATE FAXED/E-MAILED, 11/15/2010 PAGE 1 OF
Grading/TESC:
1. Please include details of erosion control measures in plans consistant with City of
Edmonds standard details. Also add note to plans "Additional Ecrosion Control Measures
Consistent With City of Edmonds Standards Provided As Needed".
2. Please change grading calcs from yards to cubic yards.
3. Provide bottom of footing (bof) elevation for residence.
4. Please review minimum requirements of erosion control for the classification of the project.
Add all minimum requirements to the civil general notes section.
5. Indicate area of disturbance. Outline on grading/tecs plan and label with square footage of
the area.
6. Add note to plans: "All disturbed areas on and off site shall be compost amended to meet
requirements of BMP T5.13 in the Stormwater Manual, Vol V, Chapter 5.
Stormwater Mitigation:
The information listed above must be presented prior to the City evaluating the stormwater
design for the project. Please review the Stormwater Handout E72 and the Stormwater
Supplement, both available on our website.
2. The project needs to be classified per ECDC 18.30.50. Once classified, the report should
describe how the project plans to comply with applicable minimum requirements (See Handout
E72)
3. Please provide a completed copy of the Worksheet available in Handout E72.
4. Developing Lots 6, 7, and 8 as proposed will result in a total of 34,366 sf of impervious
surface. The stormwater system constructed in 2001 was designed for an impervious surface
total of 30,260 sf meeting the design flow rates of that time. The existing construction of the five
lots (17,181 sf) and the cul de sac road and sidewalks (10,240 sf) equals 27,421 sf of impervious
surface that is mitigation by the City approved system meeting the code requirements of 2001.
The mitigation of runoff for the proposed impervious surface, 6945 sf, may be approached in
several ways,
a) Provide engineered calculations that show the existing system has the capacity to
handle the existing and proposed impervious surface runoff (34,366 sf). (includes all 3
proposed lots)
i) Project would be categorized as a Large Site project. See Chapter 4 of the
Stormwater Supplement for requirements.
ii) System sizing would need to meet current stormwater code flow control
requirements. See Chapter 4 of the Stormwater Supplement to find flow control
requirements for runoff In a direct discharge basin, available on the City of
Edmonds website.
DATE FAXED/E-MAILED 11/15/2010 PAGE 2 OF
iii) Soils infiltration testing by an approved method (see Supplement Chapter
4.5.2) is required for any system design using infiltration.
iiii) Physical verification of the current condition and size of the bio swale
described in the 2001 Stormwater Report for this project is required if intended
for the stormwater mitigation of the proposed construction on lots 6, 7, and 8.
b) Propose an engineered plan adding increasing capacity of the existing system. (same
requirements as 2 a above)
c) Leave existing system untouched and propose a separate system to meet stormwater
requirements for only the proposed additional impervious surface, 6,945 sf.
i) Project would be categorized as a Small Site project Category 2 if the three
lots will use a shared system for mitigation. If the lots are mitigated individually
each would be considered a Small Site Category 1. See Chapter 5 of the
Stormwater Supplement for more information.
5. Appendix C of the Supplement provides the acceptable methods for obtaining a design
infiltration rate for infiltration trenches. In addition to the methods in Appendix C of the
Supplement, the City also accepts the "D10 methodology" described in Volume III, Section 3.36,
number 2 (including Table 3.8) in the 2005 Department of Ecology Stormwater Management
Manual for Western Washington. Once the design infiltration rate is established, the City has
tables for determining the size of the infiltration trench based on the square feet of impervious
area draining to the facility or the sizing can be obtained by the applicant using the modeling
parameters in the Supplement. Attached please find a simplified sizing tool for low impact
development or detention systems. This tool can anly be used for projects that are categorized
as Small Site Category 1 or 2 sites (under 10,000 sf imp surface).
Drainage/Utility Plan:
1. How will the runoff from the driveway be connected to the stormwater system? Show on
plans.
2. Plat map shows stormwater stub at lower southeast property corner. Does that stub exist?
If so , please show on plans for future reference if needed. There is no requirement to
connect there instead of the proposed connection at the west easement.
3. Please note on plans "Required separation of utilities shall be met per City of Edmonds and
industry standards." on Drainage/Utility plan.
4. Label water meter as existing or proposed.
5. Note driveway material on plans.
6. Show existing storm line on plans. Include rim and invert elevations at all catch basins.
DATE FAXED/E-MAILED 11/15/2010 PAGE 3 OF 4
7. All detention etc. systems must be shown on the Drainage Plan. Include all rim and invert
elevations, pipe size material and length, catch basin type, and swale dimensions.
8. Show connection of tightline/roof drains to storm system from house to storm line in
easement. A catch basin must be installed at point of connection. Provide rim and all invert
elevations.
9. Show all utilities on plans (sewer, gas, power, water) from the connection at the property line
or easement to the point of connection to the residence.
10. Show 4-6"side sewer clean out at house.
11. Label all pipe with length, material and size.
Please resubmit 3 copies of the revised plans/documents to a Development Services Coordinator. Please
contact me at 425-771-0220 if you have specific questions regarding these plan corrections.
DATE FAXED/E-MAILED 11/15/2010 PAGE 4 OF 4
StormwaterBest Management Practices Simplified Sizing Tool -City of Edmonds
Table 3, Infiltration BMP sizing factors.
%percent
Sizing factors developed to luuit the post -development 10 -year recurrence interval flaw to 0,25 cubic feet per second (afs) per
acre of impervious surface area.
b Sizing factors developed to limit recurrence interval flow rates to: 2yr=0.07 cislacre; Illy€=0.25 cfs/acre; and 100yr-0.45
cubic feet per second (cfs) per acre of impervious surface area.
° BMP area is calculated as a function of impervious area draining to it: BMP Area (square feet) � Impervious Area (square feet)
x Sizing Factor (9/0)/100.
d Sizing factors are for bioretention facility bottom area. Total footprint area may be calculated based on side slopes (3I3:IV),
panding depth, and freeboard.
Surface pool drawdown time exceeds 24 hours for 0.13 and 0.25 inch per hour infiltration rates.
r SMP length is calculated as a function of impervious area draining to it: BM -P Length (feet) = Impervious Area. (square feet) x
Sizing Factor (°1%)/100.
it M6.04140.000 Sedh Wy brnpcould c
Herrera Environmental Consultants 12 April 29, 2010
Sizing Factor
Native Soil
(% of contributing impervious
Facility
Design
area)
Category 1Category
2
Overflow
Infiltration Rate
BMP
Depth
(inches/hour)
Standard'
Standard b
Sizing Equation
0.13
14.2%
153%
6 inch
0,25
9.7%
9.7%
bonding
depth
0.5
6.8%
6.8%
Bioreten#ion Bottom Area
Bioretenticn
2.0
3.6%
3.9%
(square feet) = impervious
Cell G'd
Area (square feet) x Sizing
0.13
9.6%
9.6%
I2 inch
factor (%)1100
0.25
6.2/
6.2/
Z., j t1
ponding
depth `
0.5
4.2%
4.2%
2.0
2.2%
2.3%
0.25
9,1%
9.1%
1.5 foot
depth
0.5
6.2%
6.2%
Infiltration Trench .Length
Infiltration
2.0
2.3%
2.9%
(feet) = Impervious Area
Trench e
(square feet) x Sizing Factor
0.25
5.4%
5,4%
3 foot
(%)/100
depth
0.5
4.0%4.0°/P
2.0
1.8%
2.0%
0.25
3.7%
3.7%
Gravel less Chamber Length
Gravelles€
0.5
2.7%
2 7°/P
(feet) = Impervious Area
Chamber
(square feet) x Sizing Factor
2.0
1.3%
IA%
(%)1100
4 foot
0.5
6.2%
6.2%
depth
2.0
3.0%
3.1%
Drywell Area (square feet) _
Drywell P
Impervious Area (square feet)
6 foot
0.5
4.7%
4.8%
x Sizing Factor (°/u)/100
depth
2.0
2,4%
2.5%
%percent
Sizing factors developed to luuit the post -development 10 -year recurrence interval flaw to 0,25 cubic feet per second (afs) per
acre of impervious surface area.
b Sizing factors developed to limit recurrence interval flow rates to: 2yr=0.07 cislacre; Illy€=0.25 cfs/acre; and 100yr-0.45
cubic feet per second (cfs) per acre of impervious surface area.
° BMP area is calculated as a function of impervious area draining to it: BMP Area (square feet) � Impervious Area (square feet)
x Sizing Factor (9/0)/100.
d Sizing factors are for bioretention facility bottom area. Total footprint area may be calculated based on side slopes (3I3:IV),
panding depth, and freeboard.
Surface pool drawdown time exceeds 24 hours for 0.13 and 0.25 inch per hour infiltration rates.
r SMP length is calculated as a function of impervious area draining to it: BM -P Length (feet) = Impervious Area. (square feet) x
Sizing Factor (°1%)/100.
it M6.04140.000 Sedh Wy brnpcould c
Herrera Environmental Consultants 12 April 29, 2010
StormwaterSest Management Practices Simplified Sizing Tool—City of Edmonds
Unlike the linear relationships for infiltration facilities, the y-axis intercept of the regression line
is not zero. Because the relationship is linear and the y -intercept is an integer, the slope of the
line ("Factor") and the y -intercept ("Intcger") can be used to calculate the pipe length as a
function of the impervious surface area draining to it:
Pipe Length (feet) = [Factor x Impervious Area (square feet)] + Integer
As an example, for a project subject to the Category 2 site standards, the length of a 30 inch
diameter pipe in feet would be calculated by multiplying the contributing impervious surface
area (in square feet) by 0.0185 and then adding 13.6.
The low flow orifice diameter required to meet standards varies by contributing area as shown in
Tables 5 and 6 for Category 1 and Category 2 sites, respectively. For intermediate areas the
orifice diameter should be rounded down to the next smallest area shown iii the table. For
Category 2 sites this may result in a detention pipe that somewhat over -achieves the 2 -year
standard and under -achieves the 10- and 100 -year flow control standards.
Use of the simplified sizing tool is Iimited to sites with up to 10,000 square feet of impervious
surface area. However, modeling was performed for Category 2 sites up to 0.5 acres, Sizing
results for these larger contributing areas were included in the data set used to develop the sizing
equations, and these equations can be used as rule of thumb sizing for City design review of
submittals for larger sites.
Table 5. .Detention pipe look -up table for Category 1 sites.
Contributing ftnpervious
Pipe Volume a
Length
of Pipe`' (ft) for Given Inside Diameter
Surface Area (sf)
(c f)
Minch
24 -inch 30 -inch 36 -inch
2,000
73
41
22 15
11
2,500
89
49
30 18
12
3,000
109
61
33 23 L
16
3,500
122
38 24
17
41000
142
8I
45 : `: 29
20
41500
IGO
..
95
49 .: 32 ;"
23
5,000
181
56 ::., 35 ;.:
25;;
sf-square feet; ef---cubic feet
a Pipe volume is average required for all pipe diameters, which differ somewhat due to varying orifee size.
u Detention pipe sized to aebieve Category 1 detention standard: 0.25 efs per acre of impervious surface area for the 10 -year
recurrence interval flow.
0,5" orifice
0.625" orifice
0.75" orifice
0.875" orifice
r V&- oil JO -WO elomn�n_tp r edsLh.�f-Id—
April 29, 2Q9U 15 Herrera Environmental Consultants
GENERAL NOTES
1. ALL MATERIALS AND WORK SHOWN ON THESE PLANS SHALL CONFORM TO
THE CITY OF EDMONDS STANDARD PLANS AND DETAILS, THE FOLLOWING
SPECIFICATIONS AND CODES, AND ALL OTHER APPLICABLE LOCAL MUNICIPAL,
STATE, AND FEDERAL CODES, RULES AND REGULATIONS:
- CURRENT INTERNATIONAL BUILDING CODE (IBC)
- 2010 WSDOT/APWA STANDARD SPECIFICATIONS FOR ROAD, BRIDGE AND
MUNICIPAL CONSTRUCTION
- WASHINGTON STATE DEPARTMENT OF ECOLOGY STORMWATER MANAGEMENT
MANUAL FOR THE PUGET SOUND BASIN (CURRENT EDITION)
2. STANDARD PLAN AND TYPE NUMBERS INDICATED ON THESE DRAWINGS
REFER TO CITY OF EDMONDS STANDARD DETAILS, UNLESS NOTED OTHERWISE
3. A COPY OF THESE APPROVED PLANS MUST BE ON THE JOBSITE WHENEVER
CONSTRUCTION IS IN PROGRESS.
4. DEVIATIONS FROM THESE PLANS MUST BE APPROVED BY THE ENGINEER OF
RECORD AND THE LOCAL GOVERNING AUTHORITY.
5. CONTRACTOR SHALL RECORD ALL APPROVED DEVIATIONS FROM THESE
PLANS ON A SET OF "AS -BUILT" DRAWINGS AND SHALL SUMMARIZE ALL AS -
BUILT CONDITIONS ON ONE SET OF REPRODUCIBLE DRAWINGS FOR SUBMITTAL
TO THE OWNER PRIOR PROJECT COMPLETION AND ACCEPTANCE. A SET OF AS -
BUILT DRAWINGS SHALL BE SUBMITTED TO THE CITY OF EDMONDS PRIOR TO
FINAL APPROVAL OF THE BUILDING OCCUPANCY/FINAL PROJECT APPROVAL.
6. ELEVATIONS SHOWN ARE IN FEET. SEE SURVEY FOR BENCHMARK
INFORMATION.
7. THE LOCATIONS OF EXISTING UTILITIES AND SITE FEATURES SHOWN HEREON
HAVE BEEN FURNISHED BY OTHERS BY FIELD SURVEY OR OBTAINED FROM
AVAILABLE RECORDS AND SHOULD THEREFORE BE CONSIDERED APPROXIMATE
ONLY AND NOT NECESSARILY COMPLETE. IT IS THE SOLE RESPONSIBILITY OF
THE CONTRACTOR TO INDEPENDENTLY VERIFY THE ACCURACY OF ALL UTILITY
LOCATIONS SHOWN AND TO FURTHER DISCOVER AND PROTECT ANY OTHER
UTILITIES NOT SHOWN HEREON WHICH MAY BE AFFECTED BY THE
IMPLEMENTATION OF THIS PLAN. CONTRACTOR SHALL VERIFY LOCATION,
DEPTH, SIZE, TYPE AND CONDITION OF EXISTING UTILITY LINES AT CONNECTION
OR CROSSING POINTS BEFORE TRENCHING FOR NEW UTILITIES. ENGINEER
ASSUMES NO RESPONSIBILITY FOR THE COMPLETENESS OR ACCURACY OF THE
EXISTING UTILITIES AND SITE FEATURES PRESENTED ON THESE DRAWINGS.
ENGINEER SHALL BE NOTIFIED IMMEDIATELY OF CONFLICTS THAT ARISE.
8. CONTRACTOR SHALL LOCATE AND PROTECT ALL UTILITIES DURING
CONSTRUCTION AND SHALL CONTACT THE UNDERGROUND UTILITIES LOCATION
SERVICE (1-800-424-5555) AT LEAST 48 HOURS PRIOR TO CONSTRUCTION.
9. CONTRACTOR SHALL VERIFY ALL CONDITIONS AND DIMENSIONS AT THE
PROJECT SITE BEFORE STARTING WORK AND SHALL NOTIFY OWNER'S
REPRESENTATIVE OF ANY DISCREPANCIES.
10. PIPE LENGTHS WHERE SHOWN ARE APPROXIMATE AND MAY CHANGE DUE TO
FIELD CONDITIONS.
11. CONTRACTOR SHALL OBTAIN A COPY OF THE GEOTECHNICAL REPORT
(WHERE APPLICABLE) AND SHALL THOROUGHLY FAMILIARIZE HIMSELF WITH
THE CONTENTS THEREOF. ALL SITE WORK SHALL BE PERFORMED IN STRICT
COMPLIANCE WITH THE RECOMMENDATIONS OF THIS REPORT.
12. STRUCTURAL FILL MATERIAL AND PLACEMENT SHALL CONFORM TO THE
RECOMMENDATIONS OF THE PROJECT GEOTECHNICAL REPORT.
13. MANHOLES, CATCH BASINS, UTILITIES AND PAVEMENT SHALL BEAR ON
MEDIUM DENSE TO VERY DENSE NATIVE SOIL OR COMPACTED STRUCTURAL
FILL. IF SOIL IS DISTURBED, SOFT, LOOSE, WET OR IF ORGANIC MATERIAL IS
PRESENT AT SUBGRADE ELEVATION, REMOVE AND REPLACE WITH COMPACTED
STRUCTURAL FILL PER GEOTECHNICAL REPORT.
14. SEE ARCHITECTURAL DRAWINGS FOR PERIMETER FOUNDATION DRAINS.
FOUNDATION DRAINS SHALL BE INDEPENDENT OF OTHER SITE DRAIN LINES AND
SHALL BE TIGHTLINED TO THE STORM DRAIN SYSTEM WHERE INDICATED ON
THE PLANS.
15, ALL REQUIRED STORMWATER FACILITIES MUST BE CONSTRUCTED AND IN
OPERATION PRIOR TO INSTALLATION OF ANY PAVEMENT UNLESS OTHERWISE
APPROVED BY THE ENGINEER.
18. ALL ROOF DRAINS, PERIMETER FOUNDATION DRAINS, CATCH BASINS AND
OTHER EXTERNAL DRAINS SHALL BE CONNECTED TO THE STORM DRAINAGE
SYSTEM, UNLESS NOTED OTHERWISE.
19. CONTRACTOR SHALL OBTAIN AND PAY FOR ALL PERMITS REQUIRED FOR
INSTALLATION OF ALL SITE IMPROVEMENTS INDICATED ON THESE DRAWINGS.
20. AS A MINIMUM REQUIREMENT, ALL DISTURBED AREAS ON AND OFF SITE
SHALL BE REPLACED WITH COMPOST AMENDED SOIL PER STORMWATER
MANUAL DETAIL T5.13.
21. ALL DISTURBED SOIL AREAS SHALL BE SEEDED OR STABILIZED BY OTHER
ACCEPTABLE METHODS FOR THE PREVENTION OF ON-SITE EROSION AFTER THE
COMPLETION OF CONSTRUCTION. SEE EROSION CONTROL PLANS FOR SPECIFIC
GRADING AND EROSION CONTROL REQUIREMENTS.
22, THE CONTRACTOR SHALL KEEP OFF-SITE STREETS CLEAN AT ALL TIMES BY
SWEEPING. WASHING OF THESE STREETS WILL NOT BE ALLOWED WITHOUT
PRIOR APPROVAL.
23. SLOPE OF FINISHED GRADE SHALL BE CONSTANT BETWEEN FINISHED
CONTOURS OR SPOT ELEVATIONS SHOWN.
Zulauf, JoAnne
From:
Zulauf, JoAnne
Sent:
Monday, November 15, 2010 8:03
PIVI
10:
'tomberg58@yahoo.com'
Subject:
Clearwater Bld20100757
TIO
bid2OtOO757-Clear2O1011t515243383
GENERAL
water-l.doc (...
Please find Engineering comments attached.
6.pdf (153 I(B).-
NOTES.doc (38 KB)
JoAnne ZulaLIf
Engineering Technician
City of Edmonds
(425) 771-0220 x1324
zulauf@cEedrnonds,wa.us