Cambell Garage.9.20.16.Resubmittal-Drainage Plan.pdfW. .-
Date Prepared: September 15th 2016
Site Address: 209 Castpers ST
Edmonds WA, 98020
Parcel Number: 27032400215300
Prepared By:
Joe Bissell CESCLE
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Reviewed By: Donna L. Breske, P.E.
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Donna L Breske PE, LLC
6621 Foster Slough Road
Snohomish, WA 98290
Phone:(425)334-9980
Email: donnabreske@comcast.net
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CITY COPY
Bioretention sizing
Report for Kurt &
W. .-
Date Prepared: September 15th 2016
Site Address: 209 Castpers ST
Edmonds WA, 98020
Parcel Number: 27032400215300
Prepared By:
Joe Bissell CESCLE
RE,
'N", VFIJ) 1r, 1 'q`
I" i
Reviewed By: Donna L. Breske, P.E.
C -A
Donna L Breske PE, LLC
6621 Foster Slough Road
Snohomish, WA 98290
Phone:(425)334-9980
Email: donnabreske@comcast.net
Campbell
September 15, 2016
This report is prepared to provide design information for BMP LID's (Bioretention and
Transition Zone Flow Dispersion). The site consists of 40,791.00 square feet (0.94acres). The site
address is 209 Caspers ST, Edmonds, WA 98020. There is an existing house on site that will
remain. A new shop and driving surface is to be added to the site. The result of all new
impervious is 6,758 of new regulated impervious area to be routed to LID BMP's on site.
The existing on site driveway in the south east corner of the site has been used as
temporary construction access for construction activities on site thus far, and is proposed to be
used for the installation of the Bioretention. The said driveway will be removed once it's need
for temporary construction access has come to an end. Existing power, sewer,
and gas are shown on site plan. Per site visit on 9-7-2016 CESCL Joseph Bissell confirms no
indication of critical areas on site. A survey was provided by Insight Engineering Company which
included the Campbell boundary, location of existing house, and existing topograpy.
The site has dark and light brown sandy loam. Soil test holes and information was
provided by Conrad C, Elledge. Results of the soil logs can be found in Appendix B. Post
construction soil in the disturbed areas, not covered by impervious surface, are to be installed
in accordance to BMP T5.13. Topsoil and duff are to be stockpiled separate from other material.
TESC and SWPP elements have previously designed for the site
and are included in the drawing set dated 11-5-2016 .
Stormwater Management BMP's selected for this project
1. BMP T5.13 Post -Construction Soil Quality and Depth. Topsoil is to be stockpiled separately
and spread on site in accordance with BMP T5.13.
2. BMP T5.1413 Bioretention for On-site Stormwater Management
Purpose and definition
Bioretention systems are vegetated stormwater management systems consisting of an
excavated area partially filled with a bioretention soil mix and replanted using plants from a
specific list.
3. BMP T5.12 transition zone, Sheet Flow Dispersion using transition zones are proposed for
runoff from the driveway. The applicable 10 -foot flow paths for flow exiting from the transition
zone are included in the design. Utilization of the Sheet Flow Dispersion using transition zones,
as explained above, ensures a flow length that will allow infiltration into the native ground,
coupled together with a hydraulic residence flow path to also allow time for evaporation. Since
the design threshold parameters are met, the performance standard is expected.
Sizing of the bio -retention facility is based upon city of Edmonds handout E72 A. A Design
infiltration rate of 0.5 in/hr was chosen, and a 12" ponding depth. From table 5 in the E72 A
handout, it is required that 4.2% of bio -retention bottom area is provided.
Total impervious area routed to the bioretention is 4,025 SF (0.042 X 4,015 = 169 sf). Accordingly,
for this Category 2 site, 169 sf of bioretention bottom area is proposed. See appendix A for sizing
paramaters from the E72 A handout.
VICINITY MAP
N. T. S.
PREPARED BY: VICINITY MAP KURT & CARI C"BELL
DONNA L BRESKE PE, LLC
P.O. BOX 1523
SNOHOMISH, WA 98291
PHONE: (425) 334-9980 ADDRESS: 209 GASPERS STREET, EDMONDS, WA
DonnoBreske®comcost.net ISSUE DATE: 9-9-2016 FIGURE: 1 of 1
AREA TO BE ROUTED TO TRANSITION
--.._ _. ..... _ . nucw cuna
PAVED
1,104s
PAVED i
2,733 5
PROPOSED ARE TO BE ROUTED TO BIORE7ENTION 4,025. 00 SF
PROPOSED ARE TO BE ROUTED TO T AN TION 7ONF FLOWPATHS 2.733.00 SF
TOTAL IMPERVIOUS ROUTING AREA = - 6,758.00 SF
PREPARED BY.-
DONNA L BRESKE PE, LLC
6621 FOSTER SLOUGH RD.
SNOHOMISH, WA 98290
PHONE. (425) 334-9980
DONNABRE SKE COMCAST NET
IMPERVIOUS AREA ROUTING EXIBIT
TAX NO. 27032400215300 SITE ADDRESS: 209 CASPERS STREET, EDMONDS, WA
OWNER: KURT & CARI CAMBELL
ISSUE DATE. 9-2-2016
PA 710
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BIORETENTION SIZING SUPPORTING
DOCUMENTS
Table 2. LID BMPs and Configurations for Simplified Sizing Method.
The permeable pavement BMP described here is
designed to manage only the water that falls upon it,
and is not intended to take stormwater run-on from
other areas. A typical pavement design is shown in
Figure A-1. For more specific design considerations,
see the City Engineering Division's Permeable
Pavement Policy.
Rain Gardens (Bioretention)
Bioretention facilities (also known as rain gardens) are
shallow depressions with a designed soil mix and
plants adapted to the local climate and soil moisture
conditions. The healthy soil structure and vegetation
promote infiltration, water storage, and slow release of
stormwater flows to more closely mimic natural
conditions. The simplified sizing approach applies
only to bioretention facilities that do not have an
underdrain to intercept infiltrated runoff, or an
impermeable liner impeding infiltration to underlying
soil. Sizing factors are provided for two design
variations: a 6 -inch and 12 -inch ponding depth. A
typical bioretention design is shown in Figure A-2.
Infiltration Trench
The infiltration trench BMP is based on guidance for
downspout infiltration trench designs, presented in the
Ecology Manual (Ecology 2005). A typical trench
design is shown in Figure A-3. This BMP consists of
an aggregate -filled trench where collected stormwater
is temporarily stored and then infiltrated into the
underlying soil. Sizing factors are provided for two
design variations: a 1.5 -foot and 3 -foot aggregate
depth in the trench. For both trench depths, the trench
is 24 inches wide.
Gravelless Chamber
The gravelless chamber BMP is based on guidance
presented in the Kitsap County Stormwater
Management Design Manual (Kitsap County 1997). A
typical chamber design is shown in Figure A-4. This
BMP consists of a buried chamber, typically made of
durable plastic or other prefabricated material, within
which collected stormwater is temporarily stored and
then infiltrated into underlying soil. Gravelless
chambers create an underground cavity that can
provide a greater void volume than infiltration
trenches, and often require a smaller footprint because
they can store more runoff than a trench filled with
drain rock in a comparable space. Per Kitsap County
requirements, the chamber must have a minimum void
volume of 2.6 cubic feet per linear foot, and a
minimum infiltrative surface of 2.8 square feet per
linear foot. These same requirements are suitable for
applications in Edmonds.
Drywell
The drywell BMP is based on guidance for downspout
infiltration drywell design, presented in the Ecology
Manual (Ecology 2005). A typical drywell design is
shown in Figure A-5. This BMP consists of an
aggregate -filled hole where collected stormwater is
temporarily stored and then infiltrated into the
underlying soil. Dtywells are similar to infiltration
trenches but are typically deeper and require less site
area. Sizing factors are provided for two drywell
design variations: a 4 -foot and a 6 -foot aggregate
depth.
BMP Design Requirements
To use the simplified sizing method, the BMP design
requirements listed in Table 3 must be met. Additional
requirements that you must account for in your design
(including infiltration rate testing methods, infiltration
rate correction factors, setbacks, and vertical
separation from the bottom of the facility to the
underlying water table) are presented in the
Stormwater Supplement and the Ecology Manual
(Ecology 2005).
Revised 12/21/2015 E72B — BMV Sizing Handout page 3 of 17
Design Infiltration Rate
BMP Design Configuration
BMP Sizing Method (inches per hour)
LID Runoff Reduction Methods
Permeable Pavement 1 0 to 5% Subgrade Slope
Flow Control Credit > 0.13
I I" P.�0"i,i"
.. a
Rain Gardens (Bioretention) 6- and 12 -inch Ponding Depth Sizing Factor 0.25
]nfi tration Trench
�
1.5 anPod 3-foot�—Depth
Sizing Factor
0.25 —2.0
Gravelless Chamber
Sizina Factor
0.25-2.0
L.Drywell
4 and 6 -foot Depth
Sizing Factor
0.5-2.0
The permeable pavement BMP described here is
designed to manage only the water that falls upon it,
and is not intended to take stormwater run-on from
other areas. A typical pavement design is shown in
Figure A-1. For more specific design considerations,
see the City Engineering Division's Permeable
Pavement Policy.
Rain Gardens (Bioretention)
Bioretention facilities (also known as rain gardens) are
shallow depressions with a designed soil mix and
plants adapted to the local climate and soil moisture
conditions. The healthy soil structure and vegetation
promote infiltration, water storage, and slow release of
stormwater flows to more closely mimic natural
conditions. The simplified sizing approach applies
only to bioretention facilities that do not have an
underdrain to intercept infiltrated runoff, or an
impermeable liner impeding infiltration to underlying
soil. Sizing factors are provided for two design
variations: a 6 -inch and 12 -inch ponding depth. A
typical bioretention design is shown in Figure A-2.
Infiltration Trench
The infiltration trench BMP is based on guidance for
downspout infiltration trench designs, presented in the
Ecology Manual (Ecology 2005). A typical trench
design is shown in Figure A-3. This BMP consists of
an aggregate -filled trench where collected stormwater
is temporarily stored and then infiltrated into the
underlying soil. Sizing factors are provided for two
design variations: a 1.5 -foot and 3 -foot aggregate
depth in the trench. For both trench depths, the trench
is 24 inches wide.
Gravelless Chamber
The gravelless chamber BMP is based on guidance
presented in the Kitsap County Stormwater
Management Design Manual (Kitsap County 1997). A
typical chamber design is shown in Figure A-4. This
BMP consists of a buried chamber, typically made of
durable plastic or other prefabricated material, within
which collected stormwater is temporarily stored and
then infiltrated into underlying soil. Gravelless
chambers create an underground cavity that can
provide a greater void volume than infiltration
trenches, and often require a smaller footprint because
they can store more runoff than a trench filled with
drain rock in a comparable space. Per Kitsap County
requirements, the chamber must have a minimum void
volume of 2.6 cubic feet per linear foot, and a
minimum infiltrative surface of 2.8 square feet per
linear foot. These same requirements are suitable for
applications in Edmonds.
Drywell
The drywell BMP is based on guidance for downspout
infiltration drywell design, presented in the Ecology
Manual (Ecology 2005). A typical drywell design is
shown in Figure A-5. This BMP consists of an
aggregate -filled hole where collected stormwater is
temporarily stored and then infiltrated into the
underlying soil. Dtywells are similar to infiltration
trenches but are typically deeper and require less site
area. Sizing factors are provided for two drywell
design variations: a 4 -foot and a 6 -foot aggregate
depth.
BMP Design Requirements
To use the simplified sizing method, the BMP design
requirements listed in Table 3 must be met. Additional
requirements that you must account for in your design
(including infiltration rate testing methods, infiltration
rate correction factors, setbacks, and vertical
separation from the bottom of the facility to the
underlying water table) are presented in the
Stormwater Supplement and the Ecology Manual
(Ecology 2005).
Revised 12/21/2015 E72B — BMV Sizing Handout page 3 of 17
Table 5. Bioretention and Infiltration BMP Sizing Factors.
Sizing factors developed to limit the post -development 10 -year recurrence interval flow to 0,25 cubic feet per second (cfs) per acre of impervious surface
area,
s Sizing factors developed to limit recurrence interval flow rates to: 2yr-0, 07 cfs/acre; 10yr=0,25 cfs/acre; and 100yr=0.45 cfs per acre of impervious
surface area.
BMP area is ealctutalcd as a function of nnpervious area draining to it: BMP Area (square feet) = Impervious Area (square feet) x Sizing. l °actor (%)/100.
d Sizing factors arc for Woreteattion facility bottwin area. Total footprint area may be calculated based on side slopes (3H:1 V), ponding depth, and freeboard.
e BMP length is calculated as a function of impervious area draining to it: BMP Length (feet) = Impervious Area (square feet) x Sizing Factor
(%)/100.
Revised 12/21/2015 E72B - BMP Sizing Handout page 10 of 17
Native Soil
Sizing Factor
(% of contributing
BMP
Facility Overflow Depth
Design
Infiltration Rate
impervious area
Sizing Equation
I
(inches/hour)
Category 1 Category
Sites a 2 Sites n
0.25
9.7%
9.7%
0.5
6.8%
6.8%
6 inch ponding depth
lA
5.0%
5.2%
1.5
4.1%
4.4%
Bioretention
Cell �,a
2.0
3.6%
6.2%
3.9%
°
Bioretention Bottom Area (square
feet) = Impervious Area (square
feet) x Sizing Factor (%o)/100
0.5
4.2%
4.2%
12 inch ponding depth
"""°°°...... '; """"'"
3.1%
1.5
2.5%..
2.6%
2.0
2.2°/u
2.3%
0.25
9.1%
9.1%
0.5
6.2%
6.2%
1.5 foot depth of aggregate
1.0
3.8%
4.0%
Infiltration
french e
2.0
0.25
2.3%
5.4"/0
2.9%
5.4%
Infiltration Trench Length (feet) _
Impervious Area (square feet) x
Sizing Factor (/0)/100
0.5
4.0%
4.0%
3 foot depth of aggregate
1.0
2.6%
2.6%
1.5
2.1%
2.1%
2.0
1.8%
2.0%
0.25
3.7%
3.7%
travelless
Chamber a
NA
0.5
2.7%
2.7%
Gravelless Chamber Length (feet)
=impervious Area (square feet) x
Sizing Factor (0/o)/100
1.0
1.5
1.9%
1.5%
°
1.9 /o
1.6%
2.0
1.3%
1.4%
0.5
6.2%
6.2%
4 foot depth
-' 1.5
3.5%3.6%
o
Drywell Area (square feet) _
Drywell c
Impervious Area (square feet) x
Sizing Factor (%o)/100
2.0
3,0%
3.1%
0.5
4.7%
4.8%
1.0 ITITITITITIT-
3.4%
3.5%
6 foot depth
1.5
2.8%
2.9%
Sizing factors developed to limit the post -development 10 -year recurrence interval flow to 0,25 cubic feet per second (cfs) per acre of impervious surface
area,
s Sizing factors developed to limit recurrence interval flow rates to: 2yr-0, 07 cfs/acre; 10yr=0,25 cfs/acre; and 100yr=0.45 cfs per acre of impervious
surface area.
BMP area is ealctutalcd as a function of nnpervious area draining to it: BMP Area (square feet) = Impervious Area (square feet) x Sizing. l °actor (%)/100.
d Sizing factors arc for Woreteattion facility bottwin area. Total footprint area may be calculated based on side slopes (3H:1 V), ponding depth, and freeboard.
e BMP length is calculated as a function of impervious area draining to it: BMP Length (feet) = Impervious Area (square feet) x Sizing Factor
(%)/100.
Revised 12/21/2015 E72B - BMP Sizing Handout page 10 of 17
rll!�� iij I1
DRAINFIELD DESIGNS
P. O. Box 164
Lk. Stevens. WA 98258-0164
(425) 246-0734
Rob Michel
c/o
Regent Construction, Inc
7305 Soundview Dr.
Edmonds, WA 98026
16 June 2016
Re: Soils Evaluation at: 209 Caspers Edmonds, WA
Dear Fred,
This report is to provide the results of a soils review we conducted on 15 June 2016 for the
purpose of determining, the suitability of' the site for on-site infiltration facilities for the
treatment and disposal of surface waters to be generated by the proposed residence. This
review is based on the site visit, subsurface soils exploration and field reconnaissance of the
site.
Soils are deep draining loamy sands and rocky gravelly loamy coarse sands to depths of 53
inches.
It is my opinion that the property will support on-site infiltration facilities which would meet
regulation for the proposed improvements. Please see the attached copy of field notes for soil
log locations and soil data.
Thank you,
Conrad C. Elledge
Conrad C. Elledge
Washington State Certified Designer #5100169
Snohomish County Installer #12200
King County Installer #M-123
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MAITENANCE
No. 21— Bioretention
Facilities
Component ...�.•�sw
Defect�, .. .• , ,.. � . m ....-.. ,,, n ..m �.�, ,,. � ..
Condition When Maintenance is
� _ .. u,.�_...w, ... � ... .. u.., ,�,,.��,......
Maintenance Action and Expected
Needed
Results
Inlet
Energy Visible soil, missing rock, or other
Replace or rebuild energy dissipaters to
dissipaters are evidence of damage
design specifications
damaged
-
Inlet is blocked Flow into bioretention bed is impeded
Remove blockage to restore flow
Bioretention bed /
._�...
I
Sediment Sediment depth exceeds inch
.. -_
Remoovv e sediment to restore permeability
plants
accumulation
-
�-
Trash or debris Trash or debris are accumulated on b ed
Remove trash and debris
accumulation
Excessive Drawdown time > 48 hours _
Remove and replace mulch or
drawdown time
bioretention soil mix to restore
__ _� W ��
permeability, and/or clean underdrain
��w.w....w_...........�w.�...-
Uneven pond Water does not pond evenly on bed
p
Remove, replace,
ace, or reposition mulch to
...............................m,,,..,.—.m,..,..
restore even ponding
__.,
_._......
BioretentionBloretention plants are missing,
Replace plants with healthy bioretention
plants diseased, or dead
plants selected per the planting plan
........... _..
Weeds or Weeds or invasive plants growing in
Remove weeds and invasive plants,
invasive plants bioretention facility
II replace with Bioretention plants or cover
. ................................�..._�.........................
------�
.................Mulch
affected areas with mulch, as appropriate
..........m... ___w..................
Mulch is is missing
Replace mulch to maintain 2-3 inch depth
........ ..__...--�_.--......Bed
inadequate
.��...
in mulched areas of bioretention system
compaction Red••�
is compacted due to foot or
Loosen compacted bed material, or
vehicle traffic or other reason
replace as needed, to restore permeability
Sidewalk. check
Visible damage S' ........-���. —_�������........-... .,_......,..
g idewalIs, check dams, or weirs have
.__ ...---- – _ .---.,.
Repair to bring into conformance with
dams, weirs
or erosion visible erosion or other structural
facility design
damage
Flow over check Flow is blocked so that design ponding
Clear blockage to restore design ponding
dams or weirs is depth is exceeded
depth
blocked
.
Flow aroundw.. Flow is going around check dams or.........Repair
check dams, weirs, and sidewallsmmmmm
check dams or weirs so that design ponding depth is
to restore design ponding depth
weirs not attained
Grade board or Uneven flow over c � �
heck dams or weirs
--- _ � �
Repair check dams and weirs to restore
weir top not so that design ponding depth is not
design ponding depth
level attained
Overflov,,....w�
Energy Visible soil, missing rock, or other
............ ...............
Replace or rebuild energy dissipaters to
dissipaters are evidence of damage
design specifications
�66..._.__. .
damaged
�-–�w�......
.. � m _ ------
��.................................
Overflow is Flow is blocked so that standing pool
Clear overflow structure to restore design
blocked depth is above design depth
ponding depth
Underdrain system
...
as designee d
Underdrain is Flow does not passdesigned
_ system
Clean or repair underdrain system to
blocked or through underdrain system
restore design flow capacity
damaged
January 2016 Snohomish County Drainage Manual Volume V - Runoff Treatment BMPs 47