HomeMy WebLinkAbout947400034 Stormwater Mgmt
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STORMWA TER POLLUTION PREVENTION PLAN
stotmwat
Requ\re
For
Aqua Culture Systems, Inc.
Sequim, Washington
Prepared for:
Aqua Culture Systems, Inc.
P.O. Box 417
Sequim, WA 98382
Prepared by:
Zenovic & Associates, Inc.
301 East 6th Street, Suite 1
Port Angeles, W A 98362
(360) 417-0501
Fax: (360) 417-0514
Job Number 06210
September 2006
APPROVED
STORMW A TER PLAN
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Proiect Overview
Aqua Culture Systems, Inc. is planning to construct three single-family residences on 3 parcels
totaling 1.53 acres located at 240,242, and 244 Holland Drive, Port Townsend, WA. Typical
residential construction activities will take place, including grading operations, excavation, and
concrete work. The development will necessitate the construction of two infiltration ponds and three
infiltration trenches (one per residence), as well as several onsite ditches and biofiltration swales for
routing stormwater runoff. Construction will result in approximately 0.34 acre of impervious area, or
22% of the 1.53 acre site.
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Due to ih\J.sropij;ofithe site (10-15% overall slope), extensive grading operations will take place to
create' the building pad and driveway for each of the three residences. Approximately 500 cu. yd.
(0.31 acre-ft) of soil will be moved, but no soil will be brought in or removed for cut-and-fill operations.
The only areas that will not be involved in the grading operations are the preserved treed and native
vegetation areas. No groundwater issues are anticipated, and there are no significant geographic
features or environmentally sensitive areas on the site. The only notable geographic feature near the
site is a potential erosion control hazard area to the northwest; no problems are anticipated related to
this, as the area not adjacent to the site and all of the disturbed areas of the site will slope to the
southeast. The soils onsite are primarily outwash-type soils, with a thin layer of sandy loam topsoil
(up to 12") over fine sand and gravelly fine sand.
The predeveloped site is treed and relatively undisturbed. The stormwater from the majority of the
site drains to the souij1east and enters the roadside ditch along Holland Drive, which empties into the
ditch alo~~ig,hw~v 101, and eventually into Discovery Bay. The natural slope on less than one-
sixth of thenqrthwest portion of the site drains stormwater to the adjacent properties to the northwest.
Very little water drains onto the site from adjacent properties. Slopes average 10-15%. The
developed site will contain three homes totaling 0.15 acre of roof area, one shared gravel driveway
totaling 0.11 acre, three individual gravel driveways totaling 0.07 acre, two retaining walls totaling
0.01 acre, lawn, landscaping, and native vegetation totaling 0.92 acre, preserved'treed areas totaling
0.24 acre, and infiltration ponds totaling 0.03 acre. Both native vegetation and treed areas are
considered as lawn for the purposed of hydrological calculations. Three building pads will be graded
at a maximum of 2% slopes, and a shared septic drainfield and reserve area will be installed near the
southeast comer of the site. The stormwater from the disturbed areas will drain to the southeast,
where it will be treated by biofiltration swales and infiltrated by infiltration ponds. The preserved treed '
areas will be located in the northwestern portion of the site, and will continue to drain to the
northwest.
The Stormwater Site Plan and Construction Stormwater Site Plan are attached. The Stormwater Site
Plan is to be considered a part of this report.
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SWPPP, Aqua Culture Systems, Inc., Holland Drive
Page 2 of 11
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emlim,narv ~Qndi~i9Jl' SUQ)mary
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The site is bordered to the northwest, southwest, and northeast by undeveloped residential parcels
and to the southeast by Holland Drive. The predeveloped site is treed and relatively undisturbed.
The majority of the site slopes to the southeast; less than one-sixth of the northwestern portion of the
site slopes to the northwest. The overall slope of the site is 10-15%. The site drops from an
elevation of approximately 216 feet near the southwesterly border to 160 feet at the northeasterly
comer.
The runoff from the site currently enters roadside ditches along both Holland Drive and Honeymoon
Lane (located beyond the properties to the northwest), both of which empty into the ditch alongside
Highway 101, and eventually into Discovery Bay.
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Residential land use typically increases the amount of TSS, nutrients, and pesticideslherbicides in
stormwater runoff. Treatment for these pollutants will be accomplished by several biofiltration swales
to prevent any detrimental affects to Discovery Bay, the ultimate receiving water. The biofiltration
swales were sized to treat a minimum of 91 % of the runoff volume (as estimated by the methods
outlined in the Stormwater Management Manual for Western Washington (D.O.E., August 2001 )).
They were further sized to transport the flow rate generated by the 100-year storm.
SWPPP, Aqua Culture Systems, Inc., Holland Drive
Page 3 of 11
Stormwater detention will also be required to prevent coastline erosion of Discovery Bay and undue
erosion of roadside ditching. Infiltration ponds were designed and will be installed to attenuate the
flow rates of stormwater leaving the site. All stormwater from pollution-generating surfaces will be
treated by the aforementioned biofiltration swales before it enters the infiltration ponds. To reduce the
required size of the infiltration ponds, infiltration trenches will be installed for the runoff from the roofs
of the three proposed residences.
Groundwater contamination is not a concern in this area; hardpan soils effectively protect
groundwater. The groundwater depth in this area is greater than 100 feet, as shown. by groundwater
well logs from the area. Additionally, all stormwater runoff from pollution-generating surfaces will be
treated by biofiltration swales prior to infiltration.
There are no violations of water quality standards in Discovery Bay, the ultimate outfall for this
project. There is one area of Discovery Bay that is listed as "Waters of Concern" in Washington
State's Water Quality Assessment 303(d) list. That area is near the center of Discovery Bay, and the
parameter of concern is dissolved oxygen. levels of dissolved oxygen can increase with excessive
levels of nutrients. This project will not impact the dissolved oxygen concern in Discovery Bay
because all contaminated runoff will be treated by biofiltration swales prior to infiltration.
Risks of spills or discharges of priority pollutants are minimal. Residential sites pose little risk of
priority pollutant release, and the biofiltration swales will prevent contaminated runoff from leaving the
site.
Analvsis and Desion
Using the runoff treatment selection process set forth in the Stormwater Management Manual for
Western Washington (D.O.E., August 2001), it was determined that only basic treatment is required
for this site. Biofiltration swales were chosen to achieve this treatment for their ability to remove the
target pollutants (TSS, nutrients, and pesticides/herbicides) and their ease of maintenance for the
future homeowners. The biofiltration swales were designed and sized according to the methods set
forth in the manual to treat a minimum of 91 % of the runoff volume, and to transport the flow rate
produced by the 100-year storm.
It was further determined that flow control measures are required according to the Stormwater
Management Manual for Western Washington (D.O.E., August 2001). To meet these requirements,
On-site Stormwater Management BMPs and Roof Downspout Controls will be employed.
Additionally, flow control facilities in the form of infiltration ponds will be installed. These facilities
were sized using the Western Washington Hydrology Model (v2.5f created by AQUA TERRA
Consultants) to infiltrate the 100-year storm.
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Reside.ntia.1 developments do not require oil control facilities or treatmen~ for J;$OlQval..of. phOj'w:'.e~~H
Infiltration IS not a feasible form of treatment on this site because the sollt-areextrem ,
infiltrate too quickly to effect treatment of stormwater runoff. The only pollutant of concern for the
receiving waters is nutrients. For these reasons, only basic treatment is required, and the biofiltration
swales were designed to this end. As outlined in the Stormwater Management Manual for Western
Washington (D.O.E., August 2001), the swales were sized to treat a minimum of 91 % of the runoff
volume and to transport the flow rate produced by the 1 OO-year storm. A trapezoidal cross-section
was chosen with 3: 1 side slopes. The bottom width will be 1 foot and the overall depth will be 1 foot
with a 4" design depth. The top width of the swale will be 7 feet. Lengths vary among the four
swales, but none is less than 100 feet of total travel length. Swale slopes may be more than 10% in
places, so rip-rap ,check dams were designed for sections of swale that exceed 2.5% slopes. The
check dams are to be placed such that the toe of the uphill dam is at the same elevation as the top of
the downhill dam. Below 4" of swale depth, the biofiltration swales will be seeded with mix #1 as
prescribed in the Stormwater Management Manual for Western Washington (D.O.E., August 2001),
volume 5, chapter 9, table 9.4: 75-80% tall or meadow fescue, 10-15% seaside/colonial bentgrass,
and 5-10% redtop. Above 4" of swale depth, a straw mulch or sod will be installed (this is above the
design depth for treatment flow). For further details, refer to the Stormwater Site Plan.
Basic Runoff Treatment Facilities
Detailed calculations for the biofiltration swales are attached for reference.
Flow Control BMPs
As directed by the Stormwater Management Manual for Western Washington (D.O.E., August 2001),
the On-site Stormwater Management BMPs were examined and selected, and Roof Downspout
Controls were designed. The On-site Stormwater Management BMPs that will be employed on this
site are: '
· BMP T5.13, Post-Construction Soil Quality and Depth
The purpose of this BMP is to preserve the stormwater treatment and flow attenuation
functions of the naturally occurring soils. The BMP calls for soil retention (retaining the duff
layer and native topsoil) and soil quality (minimally maintaining the infiltration rate and moisture
capacity of soils, and topsoil layers with a minimum 10% dry weight organic matter, 6.0-8.0 pH
[or matching original soils], and minimum 8" depth). Development of this site will retain all
native soils onsite; the grading required is balanced, requiring only the movement of onsite
soils. This will lead to equal infiltration rates and moisture capacities as compared to the
predeveloped condition. Additionally, good quality topsoil will be provided for all disturbed
areas where the native topsoil does not meet the aforementioned criteria.
. BMP T5.21, Better Site Design
This BMP aims to use the natural topography and features of the site in development
whenever possible rather than altering them. The guidelines call for defining the development
envelope and protected areas, minimizing directly connected impervious areas, maximizing
permeability, building narrower streets, maximizing choices for mobility, and using drainage as
a design element. On this site, undisturbed areas will be clearly marked by work area barriers
prior to construction to ensure their protection. The only impervious areas on the site are the
roof areas and gravel driveways; the driveways have been arranged to minimize the directly-
connected effect. Permeability has been maximized as much as is feasible by designing onlya
SWPPP, Aqua Culture Systems, Inc., Holland Drive
Page 5 of 11
gravel driveways (permeable pavement is not feasible in this development due to cost and
maintenance requirements). There are no streets being installed, but the shared driveway is
limited to 15 feet wide, rather than the typical 1 8-20 feet. Drainage was considered from the
earliest stages of site layout, allowing for the use of natural topography in collecting and
routing stormwater runoff. Mobility choices do not apply in this particular development, as it
consists of only three residences. '
The Roof Downspout Control employed in this development is Downspout Infiltration Trenches. The
trenches were sized according to the Stormwater Management Manual for Western Washington
(D.O.E., August 2001), volume 3, chapter 3. The dimensions were adjusted from those dictated in
the manual to better fit the space limitations of the site. The runoff from the 1,792 square foot roof '
area on lot 33 will be infiltrated by a 3 foot wide, 3 foot deep, 60 foot long infiltration trench. A 4 foot
wide, 3 foot deep, 66 foot long infiltration trench will be installed on lot 34 to infiltrate the runoff from
2,635 square feet of roof area. Lot 35 will employ a 3 foot wide, 3 foot deep, 72 foot long infiltration
trench to control the runoff from the 2,154 square foot roof area on that lot. For further details on the
infiltration trenches, refer to the Stormwater Site Plan.
Detailed calculations for the infiltration trenches are attached for reference.
Flow Control Facilities
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Infiltration ponds were designed only for flow control function by following the guidelines in volume 3,
chapter 2 of the Stormwater Management Manual for Western Washington (D.O.E., August 2001).
Because the soils are not suitable for infiltration as a method of stormwater treatment, upstream
biofiltration swales will perform this function prior to emptying into the infiltration ponds. The Western
Washington Hydrology Model (v2.5f created by AQUATERRA Consultants) was used to evaluate the
hydrology of the predeveloped and developed sites, and to size the infiltration ponds. Two infiltration
ponds were designed, one placed near the upper portion of the site (pond #1), and another placed
near the roadway (pond #2). Pond #1 is 13 feet long and 3 feet deep, with a 2 foot tall overflow riser
(2 feet of working storage volume). Pond #2 is 52 feet long and 2.5 feet deep, with a 1.5 foot tall
overflow riser (1.5 feet of working storage volume). Both ponds are to be seeded with the following
seed mix: 40% dwarf tall fescue, 30% dwarf perennial rye "Barclay", 25% red fescue, and 5%
colonial bentgrass. For further details on the infiltration ponds, refer to the Stormwater Site Plan.
The hydrology of the developed site is almost identical to that of the predeveloped site. Detailed
calculations related to predeveloped and developed site hydrology and to the infiltration pondS are
attached for reference.
SWPPP, Aqua Culture Systems, Inc., Holland dnve~-
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Minimum ReQuirements
Because this project is classified as a "Large Project" according to the Stormwater Management
Manual for Western Washington (D.O.E., August 2001), all ten of the manual's minimum
requirements must be met.
. Minimum Requirement #1: Preparation of Stormwater Site Plans
This report, along with the Stormwater Site Plan, the Construction Stormwater Pollution
Prevention Plan, and the Construction Stormwater Site Plan were prepared to meet this
requirement.
. Minimum Requirement #2: Construction Stormwater Pollution Prevention Plan
A Construction Stormwater Pollution Prevention Plan has been prepared and is included as
Attachment A.
. Minimum Requirement #3: Source Control of Pollution
Because this project consists of three residential parcels, there are no applicable source
control BMPs.
. Minimum Requirement #4: Preservation of Natural Drainage Systems and Outfalls
The natural drainage systems and outfalls were previously disturbed and are unknown.
However, the existing drainage systems and outfalls were preserved to the maximum extent
practicable. The areas that previously drained to the northwest continue to do so, and the
areas that previously drained to the southeast were also preserved.
. Minimum Requirement #5: On-site Stormwater Management
On-site Stormwater Management BMPs, including Roof Downspout Control BMPs, are
employed in this project as discussed in the Analysis and Design section of this report.
. Minimum Requirement #6: Runoff Treatment
Basic treatment is required for this project. Biofiltration swales have been designed to meet
this minimum requirement as described in the Analysis and Design section of this report.
. Minimum Requirement #7: Flow Control
Flow control is achieved by the two infiltration ponds designed using Western Washington
Hydrology Model (v2.5f created by AQUA TERRA Consultants). These ponds were described
previously in the Analysis and Design section of this report.
. Minimum Requirement #8: Wetlands Protection
The project does not contain wetlands, nor does it discharge into any wetlands, either directly
or indirectly; this minimum requirement is not applicable.
. Minimum Requirement #9: Basin/Watershed Planning
There is no applicable basin or watershed plan.
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SWPPP, Aqua Culture Systems, Inc., Holland Drive
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· Minimum Requirement #10: Operation and Maintenance
An Operations and Maintenance Manual has been prepared and is included as Attachment B.
SDecial Reports and Studies
No special reports or studies have been prepared for this site. However, prior to installation of
infiltration trenches or infiltration ponds, additional soils testing is required. The results of these tests
must be provided to the design engineer a minimum of two weeks prior to planned facility installation
for review and verification of facility design. For further details regarding soils testing report contents,
refer to the Stormwater Site Plan.
Other Permits
The septic permit has already been approved by Jefferson County authorities. The location of the
septic facilities has a direct impact on the location of infiltration pond #2; the septic On-site
Wastewater Plans have been reviewed by the design engineer, and according to these plans there is
sufficient space for pond #2 to be located as designed.
Construction Stormwater Pollution Prevention Plan
A Construction Stormwater Pollution Prevention Plan has been prepared and is included as
Attachment A.
Maintenance and ODerations Manual
An Operations and Maintenance Manual has been prepared and is included at Attachment B.
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Relevant Calculations
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DETERMINATION OF FACILITIES REQUIREMENTS
Aquaculture Systems, Inc. - 240, 242, and 244 Holland Drive
Effective Pollutlon-Generating
1m rvlous Surfaces
7664.77
0.1760
Pollution-Generating
Pervious Surfaces
11119.71
0.2553
Effective Converted
1m rvlous Surfaces Pervious Surfaces
14654.80 25900.90
0.33E)4 0.5946
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Aquaculture Systems, Inc. - 240, 242, and 244 Holland Drive
Owq = 0.0166 cfs
Y = 0.~3 ft
R = 0.3333 hydraulic radius
b= "ft
A = sq. ft.
t = 44.0000 min.
s = 0.1000 slope
n = 0.2400 manning's n
z = 3.0000 side slopes
T="ft
V = ftls
b= -0.8677 ft =
Use b = 1.0000 ft
T= 3.0000 ft
A= 0.6667 sq. ft.
V= 0.0249 ftls
L= 65.69 ft
-10.41 in
0100 = 0.2270 cfs
napprox = 0.065 manning's n
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VR = 0.8200 Iffs
R = 0.273333 ft
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0.7872 .... 0.8701
VR fits within this range.
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Arequired = 0.0913 sq. ft.
This is << than A as designed above.
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A = sq. ft.
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INFILTRATION TRENCH CALCULATIONS
Aquaculture Systems, Inc. - 240, 242, and 244 Holland Drive
Required:
sq. ft. of roof area
Lt. of infiltration trench per
75
1000
INFIL TRAnON TRENCH SIZING
Standard Standard Req'd
Depth Width Length
ft ft ft
2 2 134
2 2 100
2 2 1~
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WESTERN WASHINGTON HYDROLOGY MODBL V2
PROJECT REPORT
Project Name: Aquaculture Systems, Inc.
Site Address: 240, 242, and 244 Holland Drive
City Port Townsend
Report Date 8/21/2006
Gage Port Angelis
,Data Start 1948
Data End 1993
(adjusted) Precip Scale: 0.80
PREDEVELOPED LAND OSE
Basin
Flows To
GroundWater:
Land Use
OUTWASH FOREST:
Basin 1
Extender 1
No
Acres
-
0.069327
Basin
Flows To
GroundWater:
Land Use
OUTWASH FOREST:
Basin 2
Extender 1
No
Acres
0.17514
Basin
Flows To
,GroundWater:
Land Use
OUTWASH FOREST:
Basin 4
Extender 2
No
Acres
-
0.467097
Basin
Flows To
GroundWater:
Land Use
OUTWASH FOREST:
Basin 5
Extender 2
No
Acres
-
0.790331
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Basin 3
Point of Compliance
No
Basin
Flows To
GroundWater:
Land Use
OUTWASH FOREST:
~
0.032978
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WWHM2 Report, Aquaculture Systems, Holland Drive - Page 1 of 9
DEVELOPED LAND USE
Basin
Flows To
GroundWater:
Land Use
OUTWASH GRASS:
IMPERVIOUS:
Flow
Soil Type
Outwash
Till
Saturated
Basin 4
Pond 4
No
Acres
0.340527
0.066032
Credits:
Infiltrate Disperse Porous Pavement
100 0 0
o
o
o
o
Basin
Flows To
GroundWater:
Land Use
OUTWASH GRASS:
IMPERVIOUS:
Basin 1
Extender 1
No
Acres
0.064828
0.0045
Basin
Flows To
GroundWater:
Land Use
OUTWASH GRASS:
IMPERVIOUS:
Basin 2
Extender 1
No
Acres
0.170641
0.0045
Basin
Flows To
GroundWater:
Land Use
OUTWASH GRASS:
IMPERVIOUS:
Flow
Soil Type
Outwash
Till
Saturated
Basin 5
Pond 5
No
Aores
0.558394
0.141122
Credi ts :
Infiltrate Disperse Porous Pavement
100 0 0
o
o
o
o
Basin
Flows To
GroundWater:
Land Use
OUTWASH GRASS:
IMPERVIOUS:
Basin 3
Point of Compliance
No
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0.003866
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WWHM2 Report, Aquaculture Systems, Holland Drive - Page 2 of 9
RCBRES (POND) INFORMATION
Pond Name: Pond 4
Pond Type: Trapezoidal Pond
Pond Flows to : Basin 5
Pond Rain / Evap is not activated.
Dimensions
Depth: 3ft.
Bottom Length: 13ft.
Bottom Width: O.Olft.
Side slope 1: 2 To 1
Side slope 2: 2 To 1
Side slope 3: 2 To 1
Side slope 4: 2 To 1
Volume at Riser Head: 0.003 acre-ft.
Discharge Structure
Riser Height: 2 ft.
Riser Diameter: 12 in.
Pond Hydraulic Table
, 8taqe(ft) Area(acr) Vo]:ulIl8(acr-ft) Dschrcr(cfs) Infilt(cfs)
0.000 0.000 0.000 0.000 0.000
0.100 0.000 0.000 0.000 0.001
0.200 0.000 0.000 0.000 0.003
0.300 0.000 0.000 0.000 0.004
0.400 0.001 0.000 0.000 0.006
0.500 0.001 0.000 0.000 0.008
0.600 0.001 0.000 0.000 0.010
0.700 0.001 0.000 0.000 0.011
0.800 0.001 0.000 0.000 0.013
0.900 0.001 0.001 0.000 0.016
1.000 0.002 0.001 0.000 0.018
1.100 0.002 0.001 0.000 0.020
1.200 0.002 0.001 0.000 0.022
1.300 0.002 0.001 0.000 0.025
1.400 0.002 0.002 0.000 0.027
1.500 0.003 0.002 0.000 0.030
1.600 0.003 0.002 0.000 0.032
1.700 0.003 0.002 0.000 0.035
1.800 .0.003 0.003 0.000 0.038
1.900 0.004 0.003 0.000 0.041
2.000 0.004 0.003 0.000 0.044
2.100 0.004 0.004 0.308 0.047
2.200 0.004 0.004 0.871 0.050
2.300 0.005 0.005 1.600 0.053
2.400 0.005 0.005 2.464 0.056
2.500 0.005 0.006 3.443 0.060
2.600 0.006 0.006 4.526 0.063
2.700 0.006 0.007 5.704 0.067
2.800 0.006 0.007 6.969 0.070
2.900 0.007 0.008 8.315 0.074
3.000 0.007 0.009 9.739 0.078
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WWHM2 Report, Aquaculture Systems, Holland Drive - Page 3 of 9
Pond Name: Pond 5
Pond Type: Trapezoidal Pond
Pond Flows to : Point of Compliance
Pond Rain / Evap is not aotivated.
Dimensions
Depth: 2 . 5 it .
Bottom Length: 52ft.
Bottom Width: O.Olft.
Side slope 1: 2 To 1
Side slope 2: 2 To 1
Side slope 3: 2 To 1
Side slope 4: 2 To 1
Volume at Riser Head: 0.006 acre-ft.
Discharge Struoture
Riser Height: 1.5 ft.
Riser Diameter: 12 in.
Pond Hydraulio Table
Staqe(ft) Area(acr) Volume(acr-ft) Dschrq(~s) I:nfilt(cfs)
0.000 0.000 0.000 0.000 0.000
0.100 0.000 0.000 0.000 0.006
0.200 0.001 0.000 0.000 0.011
0.300 0.001 0.000 0.000 0.017
0.400 0.002 0.000 0.000 0.022
0.500 0.002 0.001 0.000 0.028
0.600 0.003 0.001 0.000 0.034
0.700 0.004 0.001 0.000 0.040
0.800 0.004 0.002 0.000 0.046
0.900 0.005 0.002 0.000 0.052
1.000 0.005 0.003 0.000 0.058
1.100 0.006 0.003 0.000 0.064
1.200 0.006 0.004 0.000 0.071
1.300 0.007 0.004 0.000 0.077
1.400 0.007 0.005 0.000 0.084
1.500 0.008 0.006 0.000 0.090
1.600 0.009 0.007 0.308 0.097
1.700 0.009 0.008 0.871 0.104
1.800 0.010 0.008 1.600 0.110
1.900 0.010 0.009 2.464 0.117
2.000 0.011 0.011 3.443 0.124
2.100 0.012 0.012 4.526 0.131
2.200 0.012 0.013 5.704 0.139
2.300 0.013 0.014 6.969 0.146
2.400 0.014 0.015 8.315 0.153
2.500 0.014 0.017 9.739 0.161
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WWHM2 Report, Aquaculture Systems, Holland Drive - Page 4 of 9
ANALYSIS RESULTS
Flow Frequency Return
Return Period
2 year
5 year
10 year
25 year
50 year
100 year
Periods for
Flow (cfs)
0.00023
0.000292
0.000319
0.000343
0.000356
0.000365
Predeveloped
Flow Frequency Return
Return Period
2 year
5 year
10 year
25 year
50 year
100 year
Periods for Developed Unmitigated
Flow (cfs)
0.07412
0.093739
0.105981
0.120803
0.131463
0.141852
Flow Frequency Return
Return Period
2 year
5 year
10 year
25 year
50 year
100 year
Periods for Developed Mitigated
Flow (cfs)
0.014294
0.018062
0.020412
0.023255
0.0253
0.027292
Yearly
Year
1949
1950
1951
1952
1953
1954
1955
'1956
1957
1958
,1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
,1970
1971
1972
1973
1974
1975
1976
1977
1978
,1979
Peaks for Predeveloped and Developed-Mitigated
Predeveloped
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
Developed
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
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WWHM2 Report, Aquaculture Systems, Holland Drive - PaQe 5 of 9
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
Ranked Yearly Peaks for Predeveloped and Developed-Mitigated
Rank Predeveloped Developed
1 0.0003 0.0001
2 0.0003 0.0001
3 0.0003 0.0001
4 0.0003 0.0001
5 0.0003 0.0001
6 0.0003 0.0001
'7 0.0003 0.0001
8 0.0003 0.0001
9 0.0003 0.0001
10 0.0003 0.0001
11 0.0003 0.0001
12 0.0003 0.0001
13 0.0003 0.0001
14 0.0003 0.0001
15 0.0003 0.0001
16 0.0003 0.0001
17 0.0003 0.0001
18 0.0003 0.0001
19 0.0003 0.0001
20 0.0003 0.0000
21 0.0003 0.0000
22 0.0003 0.0000
23 0.0002 0.0000
24 0.0002 0.0000
25 0.0002 0.0000
26 0.0002 0.0000
27 0.0002 0.0000
28 0.0002 0.0000
29 0.0002 0.0000
30 0.0002 0.0000
31 0.0002 0.0000
32 0.0002 0.0000
33 0.0002 0.0000
34 0.0002 0.0000
35 0.0002 0.0000
36 0.0002 0.0000
37 0.0002 0.0000
38 0.0002 0.0000
39 0.0001 0.0000
40 0.0001 0.0000
41 0.0001 0.0000
42 0.0001 0.0000
43 0.0001 0.0000
44 0.0001 0.0000
.
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WWHM2 Report, Aquaculture Systems, Holland Drive - Page 6 of 9
1/2 2 year to 50 year
Flow (CFS) Predev Final Percentage Pass/Fail
0.0001 286 0 .0 Pass
0.0001 278 0 .0 Pass
0.0001 267 0 .0 Pass
0.0001 260 0 .0 Pass
'0.0001 254 0 .0 Pass
0.0001 250 0 .0 Pass
0.0001 244 0 .0 Pass
0.0001 239 0 .0 Pass
0.0001 235 0 .0 Pass
0.0001 232 0 .0 Pass
0.0001 225 0 .0 Pass
0.0001 221 0 .0 Pass
0.0001 217 0 .0 Pass
0.0001 213 0 .0 Pass
0.0001 209 0 .0 Pass
0.0002 205 0 .0 Pass
0.0002 202 0 .0 Pass
0.0002 197 0 .0 Pass
0.0002 192 0 .0 Pass
0.0002 188 0 .0 Pass
0.0002 182 0 .0 Pass
0.0002 173 0 .0 Pass
0.0002 170 0 .0 Pass
0.0002 169 0 .0 Pass
,0.0002 159 0 .0 Pass
0.0002 157 0 .0 Pass
0.0002 150 0 .0 Pass
0.0002 148 0 .0 Pass
0.0002 148 0 .0 Pass
0.0002 146 0 .0 Pass
0.0002 141 0 .0 Pass
0.0002 137 0 .0 Pass
0.0002 136 0 .0 Pass
0.0002 129 0 .0 Pass
0.0002 125 0 .0 Pass
0.0002 121 0 .0 Pass
0.0002 116 0 .0 Pass
0.0002 113 0 .0 Pass
0.0002 110 0 .0 Pass
0.0002 106 0 .0 Pass
0.0002 103 0 .0 Pass
0.0002 99 0 .0 Pass
0.0002 88 0 .0 Pass
0.0002 86 0 .0 Pass
0.0002 80 0 .0 Pass
0.0002 80 0 .0 Pass
.0.0002 75 0 .0 Pass
0.0002 72 0 .0 Pass
0.0002 69 0 .0 Pass ,-----
0.0002 67 0 .0 Pass !r':\ r:~ n Wi ~..,. -'" .
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0.0002 63 0 .0 Pass ./ J l.=> I
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0.0002 59 0 .0 Pass I. --1.
H
0.0002 56 0 .0 Pass I SEP 20 2006:J
0.0002 52 0 .0 Pass I ' ,..../
0.0002 49 0 .0 Pass -,c"r2"NT
0.0002 47 0 . 0 Pass
0.0003 45 0 . 0 Pass L...
0.0003 44 0 .0 Pass -~--
0.0003 38 0 .0 Pass
0.0003 36 0 .0 Pass
WWHM2 Report, Aquaculture Systems, Holland Drive - Page 7 of 9
0.0003 34 0 .0 Pass
0.0003 32 0 .0 Pass
0.0003 31 0 .0 Pass
0.0003 29 0 .0 Pass
0.0003 26 0 .0 Pass
0.0003 22 0 .0 Pass
0.0003 21 0 .0 Pass
'0.0003 20 0 .0 Pass
0.0003 18 0 .0 Pass
0.0003 13 0 .0 Pass
0.0003 11 0 .0 Pass
0.0003 9 0 .0 Pass
0.0003 9 0 .0 Pass
0.0003 9 0 .0 Pass
0.0003 8 0 .0 Pass
0.0003 8 0 .0 Pass
0.0003 5 0 .0 Pass
0.0003 4 0 .0 Pass
0.0003 3 0 .0 Pass
0.0003 3 0 .0 Pass
0.0003 2 0 .0 Pass
0.0003 0 0 .0 Pass
0.0003 0 0 .0 Pass
0.0003 0 0 .0 Pass
0.0003 0 0 .0 Pass
0.0003 0 0 .0 Pass
0.0003 0 0 .0 Pass
0.0003 0 0 .0 Pass
0.0003 0 0 .0 Pass
0.0003 0 0 .0 Pass
0.0003 0 0 .0 Pass
0.0003 0 0 .0 Pass
0.0003 0 0 .0 Pass
0.0003 0 0 .0 Pass
0.0003 0 0 .0 Pass
0.0003 0 0 .0 Pass
0.0003 0 0 .0 Pass
0.0004 0 0 .0 Pass
0.0004 0 0 .0 Pass
0.0004 0 0 .0 Pass
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On-line facility volume: 0 acre-feet I
On-line facility target flow: 0 cfs.
Adjusted for 15 min: 0 cfs. L- uf.VELOPMENT
Off-line facility target flow: 0 cfs. -, .~."'-~-----'-
Adjusted for 15 min: 0 cfs.
Program and accompanying documentation as provided 'as-is' without warranty of any kind. The entire risk regarding the
performance and results of this program is assumed by the user. AQUA TERRA Consultants and the Washington State
Department of Ecology disclaims all warranties, either expressed or implied, including but not limited to implied
warranties of program and accompanying documentation. In no event shall AQUA TERRA Consultants and/or the Washington
State Department of Ecology be liable for any damages whatsoever (including without limitation to damages for loss of
business profits, loss of business information, business interruption, and the like) arising out of the user of, or
inability to use this program even if AQUA TERRA Consultants or the Washington State Department of Ecology has been
advised of the possibility of such damages.
WWHM2 Report, Aquaculture Systems, Holland Drive - Page 8 of 9
Yearly Peaks for Predeveloped
Yearly Peaks for Developed w/ Ponds
..
.....
x Developed willi FacHity
Durations
Yearly Peaks for Developed w/o Ponds
Flow Frequencies
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Attachment A
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SWPPP, Aqua Culture Systems, Inc., Holland Drive
Page 10 of 11
CONSTRUCTION
STORMWATER POLLUTION PREVENTION PLAN
For
Aqua Culture Systems, Inc.
Sequim, Washington
Prepared for:
Aqua Culture Systems, I
P.O. Box 417
Sequim, W A 98382
Prepared by:
Zenovic & Associates, Inc.
301 East 6th Street, Suite 1
Port Angeles, WA 98362
(360) 417-0501
Fax: (360)417-0514
~.;'
Job Number 06210
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September 2006
APPROVED
STORMW A TER PLAN
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Proiect Overview
Aqua Culture Systems, Inc. is planning to construct three single-family residences on 3 parcels
totaling 1.53 acres located at 240, 242, and 244 Holland Drive, Port Townsend, WA. Typical
residential construction activities will take place, including grading operations, excavation, and
concrete work. The development will necessitate the construction of two infiltration ponds and three
infiltration trenches (one per residence), as well as several onsite ditches and biofiltration swales for
routing stormwater runoff. Construction will result in approximately 0.34 acre of impervious area, or
22% of the 1.53 acre site.
Due to the slope ofthe site (10-15% overall slope), extensive grading operations will take place to
create the building pad and driveway for each of the three residences. Approximately 500 cu. ft.
(0.31 acre-ft) of soil will be moved, but no soil will be brought in or removed for cut-and-fill operations.
The only areas that will not be involved in the grading operations are the preserved treed and native
vegetation areas. No groundwater issues are anticipated, and there are no significant geographic
features or environmentally sensitive areas on the site. The only notable geographic feature near the
site is a potential erosion control hazard area to the northwest; no problems are anticipated related to
this, as the area is not adjacent to the site and all of the disturbed areas of the site will slope to the
southeast. The soils onsite are primarily outwash-type soils, with a thin layer of sandy loam (up to
12") over fine sand and gravelly fine sand.
The predeveloped site is treed and relatively undisturbed. The stormwater from the majority of the
site drains to the southeast and enters the roadside ditch along Holland Drive, which empties into the
ditch alongside Highway 101, and eventually into Discovery Bay. The natural slope on less than one-
sixth of the northwest portion of the site drains stormwater to the adjacent properties to the northwest.
Very little water drains onto the site from adjacent properties. Slopes average 10-15%. The
developed site will contain three homes totaling 0.15 acres of roof area, one shared gravel driveway
totaling 0.11 acre, three individual gravel driveways totaling 0.07 acre, two retaining walls totaling
0.01 acre, lawn, landscaping, and native vegetation totaling 0.92 acre, preserved treed areas totaling
0.24 acre, and infiltration ponds totaling 0.03 acre. Both native vegetation and treed areas are
considered as lawn for the purposed of hydrological calculations. Three building pads will be graded
at a maximum of 2% slopes, and a shared septic drainfield and reserve area will be installed near the
southeast comer of the site. The stormwater from the disturbed areas will drain to the southeast,
where it will be treated by biofiltration swales and infiltrated by infiltration ponds. The preserved treed
areas will be located in the northwestem portion of the site, and will continue to drain to the
northwest.
The Construction Stormwater Site Plan is attached and is a part of this report.
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CSWPPP, Aqua Culture Systems, Inc., Holland Drive
Page 2 of7
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The site is bordered to the northwest, southwest, and northeast by undeveloped residential parcels
and to the southeast by Holland Drive. The predeveloped site is treed and relatively undisturbed.
The majority of the site slopes to the southeast; less than one-sixth of the northwestern portion of the
site slopes to the northwest. The overall slope of the site is 10-15%. The site drops from an
elevation of approximately 216 feet near the southwesterly border to 160 feet at the northeasterly
comer.
The runoff from the site currently enters roadside ditches along both Holland Drive and Honeymoon
Lane (located beyond the properties to the northwest), both of which empty into the ditch alongside
Highway 101, and eventually into Discovery Bay.
Ad~'~'l\t~rei~
The site is bordered to the northwest, southwest, and northeast by undeveloped residential parcels
and to the southeast by Holland Drive. The site is within % mile of Highway 101.
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Page 3 of 7 L._
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Critical Areas
There are no critical areas on this site, including streams, wetlands, or other natural waterways. The
site has little hazard of erosion. The only geographic feature near the site is a potential erosion
control hazard area to the northwest; no problems are anticipated with this area, as it is not adjacent
to the site and all of the disturbed areas of the site will slope to the southeast.
Soils
The only soils testing that has been performed onsite was the testing that accompanied the septic
system design. These tests showed that the soils onsite are primarily outwash-type soils, with a thin
layer of sandy loam topsoil (up to 12") over fine sand and gravelly fine sand (logs go up to 66"). This
supports what is shown in the soil survey for Jefferson County. The survey shows Clallam gravelly
sandy loam and Hoypus gravelly loamy sand in this area. The groundwater depth in this area is
greater than 100 feet, as shown by groundwater well logs from the area.
Additional soils testing is required before installation of the infiltration facilities described in the
Stormwater Pollution Prevention Plan.
Potential Erosion Problem Areas
Because the site is grossly stable, there are few erosion-related concems. The main erosion-related
problem will be with the sandy nature of exposed soils, particularly in areas that are re-graded. Silt
fence will be installed downhill of these disturbed areas to prevent sediment from leaving the site, and
straw wattle will be installed in all construction-phase ditching to retain sediment as well. Another
concern will be keeping the infiltration ponds free of sediment during construction; the ponds will be
protected with silt fence.
Construction Stormwater Pollution Prevention Plan Elements
The Stormwater Management Manual for Western Washington (D.O.E., August 2001) requires that
twelve elements be addressed by all Construction Stormwater Pollution Prevention Plans:
. Element 1: Mark Clearing Umits
The clearing limits will be clearly marked by work area barriers. Two areas of existing trees
will be preserved near the northwest border of the site, along with several areas of native
vegetation (BMP C101). The southeastern site boundary, near Holland Drive, will be
effectively delineated by siltation fencing.
. Element 2: Establish Construction Entrance
The only route available for vehicles to enter and leave the site is near the center of the
eastern border of the site at Holland Drive. A stabilized construction entrance will be installed
here (BMP C105). rLV,--IJ:J W "'1r-
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Page 4 of 7 L._
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. Element 3: Control Flow Rates 1.1 UCl SEP 20 2006 \ JlJ
For stormwater runoff flow rate attenuation during construction, the infi tratiQn.po~c;ts ..~
prescribe~ by the Stormwater.Pollution Preven!ion Plan wi~1 be installed ~:~'~inr:s~L~t~~;i~ ~y PENT
construction process, along With four construction-phase ditches as shW
Stormwater Pollution Prevention Plan. The ditches are all located where either ditching or
biofiltration swales will be located in the developed condition. In this way, the same amount of
stormwater runoff flow rate attenuation will be achieved during construction as is required for
the developed site.
· Element 4: Install Sediment Controls
Siltation fencing will be installed along the southeast border of the site, downhill of the areas to
be disturbed, as well as around the infiltration ponds for their protection (BMP C233). Straw
wattle will also be installed in the construction-phase ditching for further protection of the
infiltration ponds (BMP C235).
· Element 5: Stabilize Soils
From October 1 st through April 30th, exposed soils that remain unworked for more than 2 days
must either be seeded (BMP C120), mulched (BMP C121), netted/blanketed (BMP C122),
covered with plastic sheeting (BMP C123), and/or sodded (BMP C124), as is appropriate.
From May 1st through September 30th, exposed soils that remain unworked for more than 7
days must be similarly protected.
. Element 6: Protect Slopes
All construction-phase ditching will be either seeded or lined with sod to create grass-lined
channels which will aid in preventing channel erosion (BMP C201). The straw wattle will also
serve to slow water in downhill ditching. If the straw wattle proves to be insufficient, rip-rap
check dams will be installed as prescribed in the permanent Stormwater Pollution Prevention
Plan. Additionally, all exposed soils on slopes will be protected with permanent seeding as
soon as the final grade is established (BMP C120).
· Element 7: Protect Drain Inlets
No storm drain inlets are present onsite or downstream of the site. This element is not
applicable.
. Element 8: Stabilize Channels and Outlets
All construction-phase ditching will be either seeded or lined with sod to create grass-lined
channels which will aid in preventing channel erosion (BMP C201). If the grass-lining erodes,
the channels will be protected with either blankets or rip-rap (BMP C202). The straw wattle will
also serve to slow water in downhill ditching. If the straw wattle proves to be insufficient, rip-
rap check dams will be installed as prescribed in the permanent Stormwater Pollution
Prevention Plan. The only pipe outlets that will be present onsite are the outlets from the two
infiltration pond overflow risers. Both of these outlets will be protected from erosion by quarry
spall pads (BMP C209).
· Element 9: Control Pollutants
The only potential pollutants that will be present onsite are the oil and fuel in the heavy
equipment, and the materials related to the concrete work needed for the home construction.
No maintenance or equipment fueling will be performed onsite to minimize the potential for fuel
or oil spills. If one should occur, the spill will be cleaned immediately with appropriate
CSWPPP, Aqua Culture Systems, Inc., Holland Drive
Page 5 of 7
absorbing materials and all contaminated soils will be removed and disposed of. To minimize
the risk of pH contamination by concrete materials, the following guidelines will be followed
(BMP C151):
o Concrete truck chutes, pumps, and internals shall be washed out only into formed areas
awaiting installation of concrete or asphalt.
o Unused concrete remaining in the truck and pump shall be returned to the originating
batch plant for recycling.
o Hand tools including, but not limited to, screeds, shovels, rakes, f1oats,and trowels shall
be washed off only into the formed areas awaiting installation of concrete or asphalt.
o Equipment that cannot be easily moved, such as concrete pavers, shall only be washed
in areas that do not directly drain to natural or constructed stormwater conveyances.
o When no formed areas are available, washwater and leftover product shall be contained
in a lined container. Contained concrete shall be disposed of in a manner that does not
violate groundwater or surface water quality standards.
o Containers shall be checked for holes in the liner daily during concrete pours and
repaired the same day.
. Element 10: Control De-watering
No de-watering is anticipated for this project. Should dewatering be required, all waters will be
discharged into a sediment trap.
. Element 11: Maintain BMPs
All stormwater and sediment control devices, including but not limited to, work area barrier,
drainage ditching, siltation fencin~, straw wattle, and infiltration ponds shall be inspected daily
from October 1 st through April 30 ,weekly from May 1 st through September 30th, and following
all major storm events. Any required repairs will be performed immediately.
. Element 12: Manage the Project
Aqua Culture Systems, Inc. will manage the project and assure that all activities abide by the
permanent Stormwater Pollution Prevention Plan and the Construction Stormwater Pollution
Prevention Plan. They will ensure that all seasonal work limitations are abided by, including
both those enumerated in this plan and those required by the local and county governments.
Aqua Culture Systems, Inc. will further coordinate between utilities and other contractors to
ensure that there is as little land disturbance and exposed soil as is necessary, and will be
responsible for the inspections and maintenance required by the Construction Stormwater
Pollution Prevention Plan. They will also be responsible for updating the Construction
Stormwater Pollution Prevention Plan throughout the construction process, as required.
Calculations
Calculations associated with predeveloped and developed site hydrology, and to the infiltration ponds
are attached for reference. The calculations associated with the biofiltration swale sizing were
referred to in sizing the construction-phase ditching and are attached also. All of these materials are
also a part of the permanent Stormwater Pollution Prevention Plan.
CSWPPP, Aqua Culture Systems, Inc., Holland Drive
Page 6 of 7 L-
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CSWPPP, Aqua Culture Systems, Inc., Holland Drive "i~
Page 7 of 7 L~_.._.::_ UiO",.;",' ut:VELOPMENT
WESTERN WASHJ:NGTON HYDROLOGY MODaL V2
PROJECT REPORT
Project Name: Aquaculture Systems, Inc.
Site Address: 240, 242, and 244 Holland Drive
City Port Townsend
Report Date 8/21/2006
Gage Port Angelis
Data Start 1948
Data End 1993
(adjusted) Precip Scale: 0.80
PRBDEVELOPBD LAND OSE
Basin
Flows To
GroundWater:
Land Use
OUTWASH FOREST:
Basin 1
Extender 1
No
Acres
0.069327
Basin
Flows To
GroundWater:
Land Ose
OUTWASH FOREST:
Basin 2
Extender 1
No
Acres
0.17514
Basin
Flows To
GroundWater:
Land Ose
OUTWASH FOREST:
Basin 4
Extender 2
No
Acres
0.467097
Basin
Flows To
GroundWater:
Land Ose
OUTWASH FOREST:
Basin 5
Extender 2
No
Acres
0.790331
Basin
Flows To
GroundWater:
Land Ose
OUTWASH FOREST:
Basin 3
Point of Compliance
No
~.'" n f\.fJ >
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i: \: SEP 2 0 2006
Acres
0.032'978
\
i
,--3
L.. ,.'
L_: -- ..,
.,
,-;:,~V~t.Dc~..~E ~,-,.
WWHM2 Report, Aquaculture Systems, Holland Drive - Page 1 of 9
DZVBLOPED LAND USB
Basin
Flows To
GroundWater :
Land Use
OUTWASH GRASS:
IMPERVIOUS:
Basin 4
Pond 4
No
Acres
0.340527
0.066032
Flow Credits:
Soil Type Infiltrate Disperse Porous Pav_ent
OUtwash 100 0 0
Till 0 0
Saturated 0 0
Basin
Flows To
GroundWater:
Land Ose
OUTWASH GRASS:
IMPERVIOUS:
Basin 1
Extender 1
No
Acres
0.064828
0.0045
Basin
Flows To
GroundWater:
Land Ose
OUTWASH GRASS:
IMPERVIOUS:
Basin 2
Extender 1
No
Acres
0.170641
0.0045
Basin
Flows To
GroundWater:
Land Ose
OUTWASH GRASS:
IMPERVIOUS:
Flow
Soil Type
OUtwash
Till
Saturated
Basin 5
Pond 5
No
Acres
0.558394
0.141122
Credits:
Infiltrate Disperse Porous Pavement
100 0 0
o
o
o
o
Basin
Flows To
GroundWater:
Land Ose
OUTWASH GRASS:
IMPERVIOUS:
Basin 3
Point of Compliance
No
rR)~~..~.~
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1
I
2006 ~~ 1
'~U"(\'\'ENT
_,C 'fLL rr... I I
WWHM2 Report, Aquaculture Systems, Holland Drive - Page 2 9f 9
Acres
0.029112
0.003866
SEP 2 0
L._
RCBlU!:S (POND) INI'ORMATZON
Pond Naae: Pond 4
Pond ~: Trapezoidal Pond
Pond Flows to : Basin 5
Pond Rain / Evap is not activated.
Diaensions
Depth: 3ft.
Bottom Length: 13ft.
Bottom Width: O.Olft.
Side slope 1: 2 To 1
Side slope 2: 2 To 1
Side slope 3: 2 To 1
Side slope 4: 2 To 1
Volume at Riser Head: 0.003 acre-ft.
Discharge Structure
Riser Height: 2 ft.
Riser Diaaeter: 12 in.
Pond Hydraulic Table
staQe (~t) Area (aor) Volume (aor-ft) Dschrcr (cfs) J:nf:i.l t (cfs)
0.000 0.000 0.000 0.000 0.000
0.100 0.000 0.000 0.000 0.001
0.200 0.000 0.000 0.000 0.003
0.300 0.000 0.000 0.000 0.004
0.400 0.001 0.000 0.000 0.006
0.500 0.001 0.000 0.000 0.008
0.600 0.001 0.000 0.000 0.010
0.700 0.001 0.000 0.000 0.011
0.800 0.001 0.000 0.000 0.013
0.900 0.001 0.001 0.000 0.016
1.000 0.002 0.001 0.000 0.018
1.100 0.002 0.001 0.000 0.020
1.200 0.002 0.001 0.000 0.022
1.300 0.002 0.001 0.000 0.025
1.400 0.002 0.002 0.000 0.027
1.500 0.003 0.002 0.000 0.030
1.600 0.003 0.002 0.000 0.032
1.700 0.003 0.002 0.000 0.035
1.800 ,0.003 0.003 0.000 0.038
1.900 0.004 0.003 0.000 0.041
2.000 0.004 0.003 0.000 0.044
2.100 0.004 0.004 0.308 0.047
2.200 0.004 0.004 0.871 0.050
2.300 0.005 0.005 1.600 0.053
2.400 0.005 0.005 2.464 0.056
2.500 0.005 0.006 3.443 0.060
2.600 0.006 0.006 4.526 0.063
2.700 0.006 0.007 5.704 0.067
2.800 0.006 0.007 6.969 0.070
2.900 0.007 0.008 8.315 0.074
3.000 0.007 0.009 9.739 0.078
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WWHM2 Report, Aquaculture Systems, Holland Drive - Page. 3 of 9
Pond Name: Pond 5
Pond Type: Trapezoidal Pond
Pond Fl.ows to : Point of Compliance
Pond Rain / Evap is not activated.
Dimensions
Depth: 2.5ft.
Botto. Length: 52ft.
Botto. Width: O.Olft.
Side sl.ope 1: 2 To 1
Side sl.ope 2: 2 To 1
Side sl.ope 3: 2 To 1
Side sl.ope 4: 2 To 1
Vol.uae at Riser Head: 0.006 acre-ft.
Discharge Structure
Riser Height: 1.5 ft.
Riser Diameter: 12 in.
Pond Hydraul.ic Tabl.e
staGe (~t) Area (.or) Volume (aor-~t) Dscbrq (ofs) %nfilt (ofs)
0.000 0.000 0.000 0.000 0.000
0.100 0.000 0.000 0.000 0.006
0.200 0.001 0.000 0.000 0.011
0.300 0.001 0.000 0.000 0.017
0.400 0.002 0.000 0.000 0.022
0.500 0.002 0.001 0.000 0.028
0.600 0.003 0.001 0.000 0.034
0.700 0.004 0.001 0.000 0.040
0.800 0.004 0.002 0.000 0.046
0.900 0.005 0.002 0.000 0.052
1.000 0.005 0.003 0.000 0.058
1.100 0.006 0.003 0.000 0.064
1.200 0.006 0.004 0.000 0.071
1.300 0.007 0.004 0.000 0.077
1.400 0.007 0.005 0.000 0.084
1.500 0.008 0.006 0.000 0.090
1.600 0.009 0.007 0.308 0.097
1.700 0.009 0.008 0.871 0.104
1.800 0.010 0.008 1.600 0.110
1.900 0.010 0.009 2.464 0.117
2.000 0.011 0.011 3.443 0.124
2.100 0.012 0.012 4.526 0.131
2.200 0.012 0.013 5.704 0.139
2.300 0.013 0.014 6.969 0.146
2.400 0.014 0.015 8.315 0.153
2.500 0.014 0.017 9.739 0.161
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WWHM2 Report, Aquaculture Systems, Holland Drive - Page 4 of 9
ANALys:rs RESULTS
F~ow Frequency Return Periods for Predeve~oped
Return Period
2 year
5year
10 year
25 year
50 year
100 year
F~ow(cfs)
0.00023
0.000292
0.000319
0.000343
0.000356
0.000365
F~ow Frequency Return Periods for Deve~oped Unmitigated
Return Period F~ow(cfs)
2 year 0.07412
5 year 0.093739
10 year 0.105981
. 25 year 0.120803
50 year 0.131463
100 year 0.141852
F~ow Frequency Return Periods for Deve~oped Mitigated
Return Period
2year
5 year
10 year
25 year
50 year
100 year
F~ow(cfs)
0.014294
0.018062
0.020412
0.023255
0.0253
0.027292
Year~y Peaks
Year
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
for PredeveJ.oped and Deve~oped-Mitigated
Predeve~oped
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
Deve~oped
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
ff] ,__F r
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SEP 2 0 2006 : '
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UtVfLODMENT
WWHM2.Report, Aquaculture Systems, Holland Drive - Page 5 of 9
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.,000
0.000
Ranked Yearly Peaks for Predeveloped and Developed-Mitigated
Rank
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
Predeveloped
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0002
0.0002
0.0002
0.0002
0.0002
0.0002
0.0002
0.0002
0.0002
0.0002
0.0002
0.0002
0.0002
0.0002
0.0002
. 0.0002
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
Developed
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
re n ~n ~,~ \
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WWHM2 Report, Aquaculture Systems, Holland Drive - Page 6 of 9
1/2 2 year to 50 year
Flow (CFS) Predev Final Percentage Pass/Fail
0.0001 286 0 .0 Pass
0.0001 278 0 .0 Pass
0.0001 267 0 .0 Pass
0.0001 260 0 .0 Pass
0.0001 254 0 .0 Pass
0.0001 250 0 .0 Pass
0.0001 244 0 .0 Pass
0.0001 239 0 .0 Pass
0.0001 235 0 .0 Pass
0.0001 232 0 .0 Pass
0.0001 225 0 .0 Pass
0.0001 221 0 .0 Pass
0.0001 217 0 .0 Pass
0.0001 213 0 .0 Pass
0.0001 209 0 .0 Pass
0.0002 205 0 .0 Pass
0.0002 202 0 .0 Pass
0.0002 197 0 .0 Pass
0.0002 192 0 .0 Pass
0.0002 188 0 .0 Pass
0.0002 182 0 .0 Pass
0.0002 173 0 .0 Pass
0.0002 170 0 .0 Pass
0.0002 169 0 .0 Pass
0.0002 159 0 .0 Pass
0.0002 157 0 .0 Pass
0.0002 150 0 .0 Pass
0.0002 148 0 .0 Pass
0.0002 148 0 .0 P~ss
0.0002 146 0 .0 Pass
0.0002 141 0 .0 Pass
0.0002 137 0 .0 Pass
0.0002 136 0 .0 Pass
0.0002 129 0 .0 Pass
0.0002 125 0 .0 Pass
0.0002 121 0 .0 Pass
0.0002 116 0 .0 Pass
0.0002 113 0 .0 Pass
0.0002 110 0 .0 Pass
0.0002 106 0 .0 Pass
0.0002 103 0 .0 Pass
0.0002 99 0 .0 Pass
0.0002 88 0 .0 Pass
0.0002 86 0 .0 Pass
0.0002 80 0 .0 Pass
0.0002 80 0 .0 Pass
0.0002 75 0 .0 Pass
0.0002 72 0 .0 Pass
0.0002 69 0 .0 Pass
0.0002 67 0 .0 Pass
0.0002 63 0 .0 Pass ~:" ff' n WI .' r-"\ .
r'~ r---'::' \
0.0002 59 0 .0 Pass 1.1.::!1 j \
0.0002 56 0 .0 Pass 1
0.0002 52 0 .0 Pass i: !
0.0002 49 0 .0 Pass SEP 20 2006 I .....)
0.0002 47 0 .0 Pass ~.
0.0003 45 0 .0 Pass
0.0003 44 0 .0 Pass L_ ' !),'VfLOPMENT I
0.0003 38 0 .0 Pass .....-._..~--~.~.__.
0.0003 36 0 .0 Pass
WWHM2 Report, Aquaculture Systems, Holland Drive - Page 7 of 9
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0003
0.0004
0.0004
0.0004
34
32
31
29
26
22
21
20
18
13
11
9
9
9
8
8
5
4
3
3
2
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
.0
.0
.0
.0
.0
.0
.0
.0
.0
.0
.0
.0
.0
.0
.0
.0
.0
.0
.0
.0
.0
.0
.0
.0
.0
.0
.0
.0
.0
.0
.0
.0
.0
.0
.0
.0
.0
.0
.0
.0
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
\\f~r<~pW2: ::l~
.~
Wat.er Quality BMP Flow and Volume
On-line facility volume: 0 acre-feet
On-line facility target flow: 0 cfs.
Adjusted for 15 ain: 0 cfs.
Off-line facility target flow: 0 cfs.
Adjusted for 15 min: 0 cfs.
"v
JEVELOPMENT
I
~..~.,.
--'-- --""_.~~._-_.--~---"
Program and accompanying documentation as provided 'as-is' without warranty of any kind. The entire risk regarding the
performance and results of this program is assumed by the user. AQUA TERRA Consultants and the Washington State
Department of Ecology disclaims all warranties, either expressed or implied, including but not l~ted to implied
warranties of program and accompanying documentation. In no event shall AQUA TERRA Consultants and/or the Washington
State Department of Ecology be liable for any damages whatsoever (including without limitation to damages for loss of
business profits, loss of business information, business interruption, and the like) arising out of the user of, or
inability to use this program even if AQUA TERRA Consultants or the Washington State Department of Ecology has been
advised of the possibility of such damages.
WWHM2 Report, Aquaculture System~, Holland Drive - Page 8 of 9
Yearly Peaks for Predeveloped
Yearly Pealts for Developed wI Ponds
....
x Developed UIIiIh Facility
..
Our.tioas
Yearly Peaks for Developed wlo Ponds
Flow ~tmcies
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WWHM2 Report, Aquaculture Systems, Holland Drive - Page 9 of 9
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~ II: 0.0913 sq. ft.
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A II: ' sq. ft.
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the y,,*, == 1 foot.
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Aw-t_ = 4.??oo sq. ft.
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OPERATIONS AND MAINTENANCE MANUAL
for
STORIYIWATER FACILITIES
For,
Aqua Culture Systems, In .
Sequim, Washington
Prepared for.
Aqua Culture Systems, Inc.
P.O. Box 417
Sequim, W A 98382
Prepared by:
Zenovic & Associates, Inc.
301 East 6th Street, Suite 1
Port Angeles, W A 98362
(360) 417-0501
Fax: (360) 417-0514
Job Number 06210
September 2006
APPROVED
STORMW A TER PLAN
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.tVf:l.DPIc1ENT
~ --- ----
Responsible Parties Contact Information
Aqua Culture Systems, Inc., Developer
Name: Steve Fager
Cell Phone: (360) 460-6437
Office Phone: (360) 582-9461
NOTE: Aqua Culture Systems, Inc. is responsible for operations and maintenance during
construction and until each lot is sold. AFTER THE SALE OF EACH LOT, THE NEW OWNER
ASSUMES RESPONSIBILITY FOR PROPER MAINTENANCE OF DRAINAGE FACIL TIES. Aqua
Culture Systems, Inc. is responsible for furnishing this information to the new lot owner.
Maintenance and Repair Log
Record any required maintenance or repair on the attached log.
Stormwater Site Plan
A copy of the Stormwater Site Plan is included for informational purposes. It is to be considered a
part of this manual.
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O&M Manual, Aqua Culture Systems, Inc., Holland Drive
Page 2 of 5
,
Wet Season Weekly Inspections Checklist:
1. Inspect any and all drainage ditches located on your lot. Remove excess accumulated silt as
necessary. Repair any erosion damage to ditches with sod or soil stabilization fabric as
appropriate.
2. Inspect any and all biofiltration swales located on your lot. Remove accumulations of silt and
sediment as necessary. DO NOT use equipment such as a backhoe or dragline to accomplish
this - it will damage the biofiltration swale. Repair any damage to the grasses with seed or
sod as appropriate - refer to the Stormwater Site Plan for proper seed/sod specifications.
3. Inspect the infiltration pond if one is located on your lot. Remove excess accumulated silt as
necessary. Repair any damage to the grasses with seed or sod as appropriate - refer to the
Stormwater Site Plan for proper seed/sod specifications.
4. Inspect the grass length of any and all biofiltration swales located on your lot. If grasses are 5-
tall or higher, mow to no less than 4" tall. Collect clippings and dispose of appropriately.
Wet Season Monthly Inspections Checklist:
1. Inspect the tightline systems for your downspouts. Clean out as necessary.
2. Inspect outlet structures of the infiltration pond if one is located on your lot. Cleanout as
necessary.
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O&M Manual, Aqua Culture Systems, Inc., tiolland Drive
Page 3 of .5
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Dry Season Bi-weekly Inspections Checklist:
1. Inspect any and all drainage ditches located on your lot. Remove excess accumulated silt as
necessary. Repair any erosion damage to ditches with sod or soil stabilization fabric as
appropriate.
2. Inspect any and all biofiltration swales located on your lot. Remove accumulations of silt and
sediment as necessary. DO NOT use equipment such as a backhoe or dragline to accomplish
this - it will damage the biofiltration swale. Repair any damage to the grasses with seed or
sod as appropriate - refer to the Stormwater Site Plan for proper seed/sod specifications.
3. Inspect the infiltration pond if one is located on your lot. Remove excess accumulated silt as
necessary. Repair any damage to the grasses with seed or sod as appropriate - refer to the
Stormwater Site Plan for proper seed/sod specifications.
4. Inspect the grass length of any and all biofiltration swales located on your lot. If grasses are S-
tall or higher, mow to no less than 2" tall. Collect clippings and dispose of appropriately.
Dry Season Bi-monthly Inspections Checklist:
1. Inspect the tightline systems for your downspouts. Clean out as necessary.
2. Inspect outlet structures of the infiltration pond if one is located on your lot. Cleanout as
necessary.
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O&M Manual, Aqua Culture Systems, Inc., Holland Drive
Page 4 of 5
M~NJ.5.tjA~G&..LOG- KE~PCl-EAN ~t1QIQcO~
PORT ANGELES HARDWOOD, LLC
Date Item/Facility Description Performed by Comments
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O&M Manual, Aqua Culture Systems, Inc., Holland Drive
Page 5 of 5