HomeMy WebLinkAboutBLD2004-00832 Stormwater Management PlanI
DRAINAGE, EROSION, AND SEDIMENT CONTROL PLAN
for
PARCEL 937800116
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Lee & Carolyn Ramey
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NORTHWESTERN TERRITORIES, INC. 717 S. Peabody St. Port 3 2 3 Q I52-849'1
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DRAINAGE, EROSION,AND SEDIMENT CONTROL PLAN
Prepared for Lee & Carolyn Ramey
April 2005
For the Property Described as
Parcel Number 937800116
Located in
Section 12, Township 30 North, Range 2 West,
Jefferson County
APPROVED
STORMWATER PLAN
APR 182005
JEFFERSON COUNTY
Prepared by DEPT.OF C,MMUNITY ► vE c ENT;► ,�of
SIGNATURE: rtAA-4111
NORTHWESTERN TERRITORIES, INC.
717 S. Peabody Street
Port Angeles, Washington 98362
Phone 360-452-8491 Fax 360-452-8498
Web Site www.nti4u.com
E-mail info@nti4u.com
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NORTHWESTERN TERRITORIES, INC.
Engineers - Land Surveyors - Geologists
,e Construction Inspection - Materials Testing
N/ I 717 SOUTH PEABODY,PORT ANGELES,WASHINGTON 98362,(360)452-8491
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Drainage,Erosion, and Sediment Control Plan
for
Parcel Number 937800116
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Drainage, Erosion, and Sediment Control Plan
for
Parcel Number 937800116
ABSTRACT
This plan was prepared to comply with the requirements of the Stormwater Man-
agement Manual For The Puget Sound Basin, published by the Washington State
Department of Ecology (DOE Manual), as required by Jefferson County. It contains
the Erosion and Sediment Control Plan in its entirety and estimates both the pre-
development and post-development offsite runoff from the project site, based on
standard 2 year, 24 hour and 25 year, 24 hour design storms. It calculates the neces-
sary parameters for the design of a stormwater outfall to salt water. It provides ad-
ditional information and guidance as necessary to comply with the DOE Manual and
to provide a reasonable level of protection against degradation of the quality of re-
ceiving waters during the construction of and as a result of the eventual full devel-
opment of this project.
Erosion control measures are also recommended.
v
Drainage, Erosion, and Sediment Control Plan
for
Parcel Number 937800116
CONTENTS
I. SCOPE 1
II. PROJECT DATA 2
A. Project Description 2
B. Existing Site Conditions 3
1. Topography 3
2. Vegetation 4
3. Drainage 5
C. Adjacent Areas 6
III. DESIGN CRITERIA 6
A. Soils 6
B. Rainfall 7
C. Hydrologic Model 8
D. Time of Concentration 9
1. Predevelopment Condition 9
2. Predevelopment Time of Concentration 10
3. Post-development Condition 10
4. Post-development Time of Concentration 11
IV. RUNOFF 11
A. Data and Calculations 12
B. Construction Details 12
C. Mitigation 12
V. EROSION AND SEDIMENT CONTROL PLAN 12
A. Site Specific Construction Phase BMPs 13
B. Stabilization and Sediment Trapping (Erosion and Sediment
Control Requirement Number 1) 14
vi
1. Stabilization of Exposed Soils 14
2. Sediment Trapping 16
C. Delineate Clearing and Easement Limits (Erosion and
Sediment Control Requirement Number 2) 18
D. Protection of Adjacent Properties (Erosion and Sediment
Control Requirement Number 3) 19
E. Timing and Stabilization of Sediment Trapping Measures
(Erosion and Sediment Control Requirement Number 4) 19
1. Timing of Installation of BMPs 19
2. Stabilization of slopes of structural BMPs 19
F. Cut and Fill Slopes (Erosion and Sediment Control
Requirement Number 5) 20
G. Controlling Off-Site Erosion (Erosion and Sediment Control
Requirement Number 6) 20
H. Stabilization of Temporary Channels and Outlets (Erosion
and Sediment Control Requirement Number 7) 20
I. Underground Utility Construction (Erosion and Sediment
Control Requirement Number 9) 21
J. Construction Access Routes (Erosion and Sediment Control
Requirement Number 10) 21
K. Removal of Temporary BMPs (Erosion and Sediment
Control Requirement Number 11) 22
L. Dewatering Construction Sites (Erosion and Sediment
Control Requirement Number 12) 22
M. Control of Pollutants Other than Sediment (Erosion and
Sediment Control Requirement Number 13) 23
1. Control of Toxic Substances 23
2. Petroleum Spills 23
N. Maintenance (Erosion and Sediment Control Requirement
Number 14) 24
O. Financial Liability 25
vii
Drainage,Erosion, and Sediment Control Plan
for
Parcel Number 937800116
I. SCOPE
This plan was prepared to provide a reasonable level of protection against damage
being caused to properties within or without the project as a result of increased
stormwater runoff resulting from the eventual full development of the project as re-
quired by Jefferson County.
The project consists of the development of a single family home on a half acre parcel.
Approximately 0.15 acres is seaward of the bluff. Photo 1 shows the location of the
Guthrie Parcel(highlighted in red)in the neighborhood.
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Photo 1
This plan calculates the rate of stormwater runoff from the site in its assumed pre-
development state of forest cover. It then calculates the rate of runoff based on a
post-developed state. It recommends the construction of a tightline pipe to convey
stormwater runoff to the foot of the bluff for dispersed discharge immediately above
the line of ordinary high water. The plan also addresses both short- and long-term
water quality impacts of the project and recommends appropriate mitigative meas-
ures.
II. PROJECT DATA
Photo 2 shows the home site for the project in the background with part of an ad-
joining parcel in the right foreground. The home will be constructed near the center
of the photo.
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Photo 2
A. Project Description
This project site presently consists of 0.32 acres of"uplands" and 0.15 acres on
steep slopes over the bluff to seaward of the building site. The project envisions
the construction of a single family home with a footprint of 2,000 square feet.
Drainage effects of landscaping will be little changed from the existing grass.
There will be a 500 square foot circular driveway. The arrangement of the im-
provements will be as shown on the site map included at the beginning of this
2
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report and as depicted on the catalog of site improvements included with the cal-
culations in appendices.
B. Existing Site Conditions
The following summary of site conditions represents existing conditions. These
are the conditions that exist before the beginning of construction. For purposes of
calculating pre-development runoff rates, the pre-developed condition was as-
sumed to be forested.
1. Topography
The parcel generally slopes to the top of the bluff to the northwest as shown
on the Neighborhood Map included at the beginning of this report. The bluff
falls sharply to saltwater. A geotechnical report for this site was prepared by
this office in July of 2002 and contains a detailed description of the bluff.
Photo 3 shows the bluff.
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Photo 4 shows the bluff from the bottom. The geotechnical report discussed
the various features shown on the bluff.
2. Vegetation
The uplands part of the site is covered with a vigorous stand of dense grass as
shown in Photo 5 below and in Photo 2 on page 2.
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Photo 5
Photo 4 shows the vegetation on the bluff. The beach below is bare.
4
3. Drainage
The entire neighborhood slopes and drains to the west. The road side ditch on
the northwest side of Victoria Loop intercepts all runoff from the road and
conveys it past the project site as shown in Photo 6.
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Photo 6
The parcel accepts minor amounts of runoff from the parcel to the immediate
northeast and a similar amount flows off the site to the parcel to the south-
west. These are sheet flows through dense grass. It is assumed that these
minor flows balance each other and they are disregarded for the remainder of
the report.
Flows from the site presently go over the bluff in sheet flow before entering
salt water across the beach.
This drainage plan was designed to return flows to their natural flow regimes
(volume, route, and velocity) before they leave the site. The one exception is
that sheet flows over the bluff will be reduced and a tightline conveyance will
be installed.
5
C. Adjacent Areas
The site is surrounded by residential lands on three sides and by marine waters
on the fourth. Photo 1 shows the neighboring parcels, the bluff, and the beach.
III. DESIGN CRITERIA
The following criteria are specific to this project and will not apply to other proper-
ties, even those that may be nearby.
A. Soils
The site may be found on map number 41 of the Soil Survey of Jefferson County
Area, published by the U. S. Soil Conservation Service. A portion of Map 41 is
reproduced here as Figure 1, with the project location marked. Map number 41
predicts that the soils on this site are type CmC.
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Figure 1
6
The Soil Survey of Jefferson County Area describes type CmC as being Clallam
gravelly sandy loam. A description of this soil series can be found on page 16 of
the Soil Survey. These soils are assigned to hydrologic group C.
Photo 3 and Photo 4 show the soil profiles where they are exposed in the bluff.
B. Rainfall
The total amount of precipitation falling over a 24 hour period during a storm
having a mean recurrence interval of 2 years, will be 1.2 inches. This informa-
tion was taken from a 2 year, 24 hour Isopluvial Map published by the U.S. Soil
Conservation Service, a portion of which is reproduced here as Figure 2.
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1014,
30N VA"
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alL
28N MENE
FEEL
27.N
26N
1 OW 9W 8W 7W 6W 5W 4W 3WW 2W ?W
Figure 2
The project location is marked on the map. The isopluvial lines represent total
precipitation in 24 hours, in tenths of inches. 2 year rainfall data is used in the
calculation of the time of concentration for the site.
The total amount of precipitation falling over a 24 hour period during a storm
having a mean recurrence interval of 25 years, will be 2.2 inches. This informa-
tion was taken from a 25 year, 24 hour Isopluvial Map published by the U.S Soil
7
Conservation Service, a portion of which is reproduced here as Figure 3. The
project location is marked on the map.
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Figure 3
The rainfall distribution is assumed to be a Type IA distribution per standard
practice in the area.
C. Hydrologic Model
This plan uses a hydrograph based method of calculating runoff which is de-
scribed in Urban Hydrology for Small Watersheds, Technical Release No. 55, and
the Western Washington Supplement to Technical Release No. 55, both pub-
lished by the U. S. Soil Conservation Service. This same type of method is given
in the King County Surface Water Design Manual, published by the King County
Public Works Department, and the Stormwater Management Manual for the
Puget Sound Basin (The Technical Manual) published by the Washington State
Department of Ecology.
This method yields runoff volumes that are significantly different from those de-
termined using the rational method. While the rational method is excellent for
conservatively sizing channels and conduits for small watersheds, it does not
adequately consider the time element of runoff that is necessary in calculating
runoff hydrographs.
8
This plan uses the suggested runoff curve numbers given in Table 2-2a of Tech-
nical Release No. 55.
D. Time of Concentration
The length of time that it takes a drop of rainfall to travel from the uppermost
point of a basin to the point of discharge from the basin, or to the point where
flows are to be calculated, is referred to as the time of concentration (Tc). This is
the sum of the time it takes for runoff to flow across the various types of flow
channels as it crosses the basin.
The following calculations are per Section III-1.4.2, pages III-1-13 through III-1-
16, of the Washington State Department of Ecology's STORMWATER MAN-
AGEMENT MANUAL FOR THE PUGET SOUND BASIN, THE TECHNICAL
MANUAL, (DOE).
1. Predevelopment Condition
The time of concentration is first determined for the existing condition of the
basin.
a. Unconcentrated Flow
Immediately after falling to the ground, rainwater initially travels as un-
concentrated sheet flow for a period of time (Tt) calculated by:
0.80
0.42 (NsL)
Tt= = 46.04 min
0.527 0.4
(P2) (S0)
Where:
Ns = 0.800 = Sheet flow Manning's n (DOE Table III-1.4)
P2 = 1.2 = 2 yr, 24 hr rainfall (in)
SO = 0.0400 = Slope of flow path(ft/ft)
L= 100 = Length(L) of flow path(ft)
9
b. Shallow Concentrated Flow
As sheet flows run together and become concentrated, they travel as
shallow concentrated flow for a period of time (Tt) calculated by:
L
Tt= = 1.39 min
60 Ks SQRT(S0)
Where: Ks = 3 =Velocity factor(Ks) (per DOE Table III-1.4)
SO = 0.0400 = Slope of flow path(ft/ft)
L = 50 = Length (L) of flow path (ft)
At this point flows run over the bluff as sheet flow.
2. Predevelopment Time of Concentration
As noted above, the time of concentration (Tc) is the sum of the time it takes
for runoff to flow across the various types of flow channels as it crosses the
basin. For the predevelopment condition:
Tc= the sum of the various Tt's = 47.43 min
This is rounded to 47 minutes for use in further calculations.
3. Post-development Condition
The time of concentration is next determined for the proposed, post-developed
condition of the basin.
a. Unconcentrated Flow
Immediately after falling to the ground, rainwater initially travels as un-
concentrated sheet flow for a period of time (Tt) calculated by:
10
0.80
0.42 (NsL)
Tt= = 26.45 min
0.527 0.4
(P2) (SO)
Where: Ns = 0.400 = Sheet flow Manning's n(per DOE Tb1 III-1.4)
Ps = 1.2 = 2 yr, 24 hr rainfall (in)
SO = 0.0400= Slope of flow path(ft/ft)
L = 100 = Length(L) of flow path(ft)
b. Shallow Concentrated Flow
As sheet flows run together and become concentrated, they travel as
shallow concentrated flow for a period of time (Tt)calculated by:
L
Tt= = 0.46 min
60 Ks SQRT(S0)
Where: Ks = 9 =Velocity factor(Ks) (per DOE Table III-1.4)
SO = 0.0400 = Slope of flow path (ft/ft)
L= 50 = Length (L) of flow path (ft)
This is the point where flows enter the conveyance system.
4. Post-development Time of Concentration
As noted above, the time of concentration (Tc) is the sum of the time it takes
for runoff to flow across the various types of flow channels as it crosses the
basin. For the post-development condition:
Tc= the sum of the various Tt's = 26.91 min
This is rounded to 27 min for use in further calculations.
IV. RUNOFF
As noted above, pre-development runoff is calculated based on the "pre-contact" con-
dition of the site per Jefferson County requirements and not as it presently exists.
11
Post-development runoff is calculated based on the proposed conditions noted above
and shown on the calculations included in the appendices.
A. Data and Calculations
Appendix I contains runoff calculations for the entire site. These are used to de-
termine the runoff from the parcel in the undeveloped and developed condition.
They are used for the design of the conveyance system. Subsections of Appendix I
are as follows:
1. Summary of various coefficients and operational values for the site.
2. Catalog of pre- and post-development land uses.
3. Raw rainfall data for the design storms falling on the site.
4. Pre-development runoff calculations for the design storms.
5. Post-development runoff calculations for the design storms.
B. Construction Details
Appendix II contains detail drawings and specifications for the conveyance sys-
tem.
C. Mitigation
To mitigate the effects of the construction of this project, it is recommended that
all runoff from the site be routed to a conveyance system, constructed per the
construction details included at the end of this report.
V. EROSION AND SEDIMENT CONTROL PLAN
This portion of the plan was prepared with the goal of preventing damage to adjoin-
ing or downstream properties due to erosion and sediment deposition and preventing
the degradation of the quality of the receiving waters during the construction phase
of this project.
12
To ensure that the provisions of this Erosion and Sediment Control Plan are fol-
lowed during construction, the complete text of this Erosion and Sediment Control
Plan should be included in the construction plans for this project. Where formal con-
struction plans will not be prepared for all or portions of the work, a copy of this
document should be made available to the contractor and appropriate subcontrac-
tors. Subcontractors that will not be receiving copies should be made aware of the
plan's existence and advised of where copies can be obtained.
Water quality controls, commonly referred to as Best Management Practices, or
BMPs, are necessary to prevent three distinct types of impacts. The first consists of
damage done as the result of soils being taken up by running water. This type of
damage typically consists of rilling, rutting and loss of topsoil. The next type of
damage is the degradation of water quality that occurs as the water transports the
smaller soil particles. The last type of damage occurs when the running water re-
duces its velocity and drops the suspended soils.
The Erosion and Sediment Control features (BMPs) of this plan were designed to
address all three types of damage with the emphasis on preventing the initial soil
uptake. Successful prevention of soil uptake will also prevent damage caused by
degradation of water quality and by soil deposition. While the measures described
below for preventing soil uptake should theoretically prevent any removal of soil,
common sense advises that additional measures will be necessary and indeed, the
DOE Manual requires additional measures. These additional measures will allow
deposition of transported soils under controlled conditions before flows leave the
project site or enter the receiving waters.
The specific types of BMPs and their locations are described immediately below.
Specific details of the BMPs are described elsewhere below.
A. Site Specific Construction Phase BMPs
The following BMPs shall be implemented in addition to any that may later be
necessary due to changing or unforeseen site conditions:
1. Silt fencing shall be installed beyond the limits of construction on the
lower side of the project (west and south sides) and maintained in
place until the soils disturbed by construction have been successfully
revegetated.
2. A stormwater conveyance system shall be constructed per the plans at
the back of this report.
3. Runoff from the site shall be routed to the conveyance system.
4. Other appropriate BMPs such as limitations on access routes, minimi-
zation of soil disturbing activities, etc. as described below shall be im-
plemented only if necessary to accomplish the objectives of this plan.
13
It is expected that minor adjustments, especially the installation of additional
BMPs where an unexpected need arises, may be necessary during the construc-
tion phase of this project. For this reason, discussions of various BMPs that are
not specifically required are included below. These BMPs should be considered
as being held in ready reserve against the possibility that they will be needed.
The following subsections discuss the various BMPs that may be incorporated in
this plan. Reasons for their use, limitations and benefits associated with specific
BMPs, and additional information are provided.
B. Stabilization and Sediment Trapping (Erosion and Sediment Control
Requirement Number 1)
These requirements are to be considered general in nature and provide a frame-
work for deciding when and where various BMPs should be utilized. They are in-
tended to provide guidance in quickly selecting BMPs for use in unexpected
situations. They apply to both soils that are not yet at final grade and to those
that are at final grade, including soil stockpiles.
1. Stabilization of Exposed Soils
The stabilization of exposed soils is the single most important element of this
plan. If exposed soils are protected such that soil particles are not picked up
by running water, erosion will not occur. Protection of exposed soil consists of
four main areas of effort.
a. Minimize Disturbance of Vegetation
Existing vegetation on the site comprises the best overall protection
against erosion. To protect this resource and to keep the risk of erosion at
a minimum, clearing and grading activities outside of the areas necessary
to construct the improvements shall be kept to an absolute minimum.
Patches of existing vegetation that are within the clearing/grading limits,
but may be left intact without hindering the project, shall be left alone
whenever possible.
Care shall be taken that existing vegetation is left intact wherever possi-
ble around the perimeter of the project and particularly along the lower
side of the project. Vegetation in drainage corridors and immediately be-
low soil disturbing activities is the most valuable and as such is to be pro-
vided with the most protection.
b. Minimize the Length of Time the Soil is Unprotected
Where grading is necessary for construction activities, the grading should
be delayed as long as reasonably possible to minimize the length of time
that the soil is exposed to the elements.
Where exposure of bare soil is necessary to accomplish certain portions of
the work, such portions of the work should be completed promptly in or-
14
der to reduce the chance of an erosive rainfall event catching the soil un-
protected.
c. Ensure Prompt Revegetation of Disturbed Areas
Every effort shall be made to ensure a healthy stand of protective vegeta-
tion is established as soon as possible. Reseeding of areas which are to be
planted with grass shall be accomplished within 14 days if grading opera-
tions are completed within a planting season. If grading operations are
completed outside of a planting season, reseeding shall occur within 7
days following the beginning of the next planting season. If substantial
portions of the project are ready for reseeding at the beginning of or dur-
ing a planting season, such portions may be promptly reseeded without
waiting for completion of work on other portions of the project.
Planting seasons are considered to be between March 1 and May 15 and
between August 15 and October 1 where irrigation is impractical. Where
irrigation is practical, the planting season is considered to be between
March 1 and October 1.
The following seed mix has been tested and found to be adequate for use
for erosion control and for slope stabilization in Western Washington:
Seed Type Percent by Weight
Chewing Fescue 40
Colonial Bentgrass,
Var. Astoria 10
Perennial Rye 40
White Clover 10
100
Other mixes, selected with regard for the soils, uses of the site, method of
application, and expected weather may be used if desired. The recommen-
dations of the seed supplier should be sought and strongly considered in
selecting a mix.
If the season or construction scheduling will not allow prompt revegeta-
tion of an area where construction activities have been completed, the
area should be covered with plastic sheeting, straw, mulch or other cov-
ering chosen to match the situation and with due regard for the length of
time that the area is expected to remain uncovered.
d. Protective Coverings
Protective coverings are highly recommended for application to exposed
soils that are not being actively worked for an extended period of time.
15
An extended period of time is considered to be 14 days between October 1
and April 30 or 45 days between May 1 and September 30.
Protective coverings include plastic sheeting, straw, mulch, commercial
sod and other coverings. The particular type of protective covering used
should be chosen based on the steepness of the slope of the area to be cov-
ered, the size or the area to be covered, the time of year, the length of time
the covering will remain, proximity to wetlands or other sensitive areas,
the amount of existing vegetation between the exposed soil and the down-
hill project boundary, cost, and the visual impact of the covering.
The best covering is existing vegetation, which should be disturbed as lit-
tle as possible. Commercial sod is the next best covering but its use is of-
ten precluded by cost. Clear plastic sheeting is suitable for steep slopes
but is difficult to apply and maintain in moderate to high winds. Black
plastic sheeting is not appropriate during growing seasons except for
short periods of time. Loose straw, either straight from bales or shredded,
makes an adequate ground covering on gentle to moderately steep slopes
(no steeper than 2 horizontal to 1 vertical) if it is wet to the point of limp-
ness. Straw is generally effective where the distance from the top to the
toe of the slope is no more than 100 feet.
Early application of gravel bases, pavements, and special landscaping
items such as washed rock over plastic sheeting is considered to be a suit-
able protective covering where otherwise required.
2. Sediment Trapping
Stormwater runoff from areas of exposed soil shall not be permitted to leave
the project site without first having passed through an appropriate sediment
trapping system or device. The type of sediment trap should be chosen based
on the potential for erosion from exposed soils, the expected velocity and
depth of flows, the proximity to downstream sensitive areas, and the length of
time that the upstream soils will remain exposed to the elements.
a. Sheet Flow Through Grassy or Heavily Vegetated Areas
Runoff from exposed slopes that are less than 150 feet from top to bottom
(measured along the slope) can be adequately treated by routing flows
through bands of dense grass of other heavy vegetation. The vegetated
band should be a minimum of one fifth as wide as the width of the ex-
posed slope, but no narrower than 10 feet. For example, a band of ex-
posed soil 75 feet wide should have a minimum of 15 feet of dense grass
for sediment trapping.
The vegetated band width above is for a slope no steeper than 10 percent.
Where the slope of the vegetated area is between 10 and 20 percent, add
16
50 percent to the minimum width. Where the slope is greater than 20
percent, the minimum width should be doubled.
For this type of sediment trapping system to be effective, flows must cross
the vegetated area in sheet flows. If flows are expected to arrive at the
vegetated band in concentrated flows, creation of a small artificial delta
may be necessary to force a sheet flow.
b. Grassy Swales
Grassy swales can be used to treat runoff from larger areas than can
sheet flows across bands of vegetation. While grassy swales are typically
thought of as permanent features, they can often be utilized during the
construction phase. Typically there is no time before the main construc-
tion effort to reshape landforms to provide the necessary slopes, widths,
etc., and then wait while the swale revegetates. Either an area must be
found that is already vegetated and that meets the minimum require-
ments for a grassy swale or commercial sod must be placed along the
sides and bottoms of the swale immediately after the swale is constructed.
The following standard requirements for grassy swales were taken from
the Draft Stormwater Guidelines published by the Washington State De-
partment of Fisheries in 1990 and are recommended for use here due to
their simplicity. More specific design criteria are more appropriate for use
on large or complex sites.
i. Soils
Gravelly and coarse sandy soils should be avoided in order to maxi-
mize water contact with vegetation and the soil surface.
ii. Design Criteria
The grassy swale should be designed based on a two-year, 24-hour
peak flow and the following:
(A) Velocity
Velocities should be less than 1.50 feet per second.
(B) Depth of Flow
The flow depth should be less than 4 inches.
(C) Slope
The longitudinal slope should average two to four percent. Rock or
log check dams or terraces should be installed as necessary to
achieve slopes of less than four percent.
17
iii. Dimensions
Grassy swales should be located to obtain maximum length. If less
than 200 feet long, the width should be increased by an amount pro-
portional to the reduction below 200 feet in order to obtain the same
area of vegetation contact.
iv. Side Slopes
Side slopes should be no steeper than three horizontal to one vertical.
c. Interceptor Swales
Interceptor swales are shallow trenches constructed with a single pass of
a large dozer equipped with one to three ripper teeth. The preferred con-
figuration of ripper teeth for construction of interceptor swales is two
teeth positioned on the outside of the ripper assembly. This type of swale
construction will tear through existing sod without removing it. Leaving
the sod in place will protect against erosion of the swale bottom on steeper
slopes.
Swales thus constructed are intended to intercept sheet flows and infil-
trate them into the soil. When flows are greater than can be infiltrated,
the swales will provide a path for runoff of excess flows. Such excess
flows will run along the swale until they are either infiltrated or they en-
ter interceptor ditches.
Interceptor swales are especially effective adjacent to property lines
which run more or less straight up and down a slope and where only sheet
flows are to be intercepted. In order to be effective, the surface of the
ground must not be regraded during the life of the swale. Grading or
blading of the surface of these swales will defeat their purpose.
Construction of interceptor swales causes only minimal disruption of the
ground contours. For this reason the swales need not be removed or oth-
erwise treated at the end of their usefulness.
d. Other Sediment Trapping Devices and Systems
Many other effective sediment trapping systems and devices are listed in
Table II-2.1 of the 1992 DOE Manual. Complete details and descriptions
of them are included elsewhere in the DOE Manual. They should be used
where appropriate and as described in the Manual.
C. Delineate Clearing and Easement Limits (Erosion and Sediment Control
Requirement Number 2)
Appropriate clearing limits, property lines, easement lines, and similar bounda-
ries shall be determined prior to starting construction. Clearing, grubbing,
grading and similar operations shall not begin until the appropriate limits are
staked in the field. Once these stakes are set, care shall be taken that the stakes
are not disturbed.
18
D. Protection of Adjacent Properties (Erosion and Sediment Control Re-
quirement Number 3)
As required by the DOE Manual, no flows from exposed or disturbed soils are to
leave the project site without first having been treated with some type of sedi-
ment trapping/filtering system or device. The proposed arrangement of these
devices and systems is described above. The individual items are discussed in
more detail in the section on Sediment Trapping above.
The protective measures shown on the site plan are designed to prevent sedi-
ment deposition on adjacent properties. To the extent that the various items are
constructed as designed and other work on the site progresses as envisioned,
sediment should not be deposited on neighboring properties.
Last minute changes in other items of work on this project, responses to previ-
ously unknown site conditions, or unexpected weather may require that revisions
to the sediment trapping provisions of this plan be made rapidly. To this end,
the previous section on Sediment Trapping contains design criteria, comments,
information about BMPs, and similar information that is intended to be used in
rapidly responding to changing needs and changing site conditions. As soon as a
previously unexpected threat to adjacent properties becomes apparent, sufficient
measures shall be taken to either eliminate the source of the threat or to provide
an adequate level of defense against the threat. The measures taken shall pro-
vide a level of defense against sediment deposition on adjacent properties at least
as secure as those provided by the remainder of this plan.
E. Timing and Stabilization of Sediment Trapping Measures (Erosion and
Sediment Control Requirement Number 4)
It is essential that the various sediment trapping systems and devices be con-
structed prior to exposing the upslope soils to the elements. Both the timing of
construction of the measures and the stabilization of the slopes of the structural
BMPs are mandatory parts of this plan.
1. Timing of Installation of BMPs
In keeping with the goal of providing positive sediment trapping or removal
for all runoff from exposed soils before the runoff leaves the project site, no
soil shall be exposed, or grading operations performed, until all of the re-
quired BMPs in the drainage path below the area to be exposed have been
completed. Clearing, grubbing, and grading operations necessary for the con-
struction of the BMPs are excepted from this requirement.
2. Stabilization of slopes of structural BMPs
It is critical that the slopes of ditches, berms, ponds, and similar structural
items be stabilized. These slopes will not only shed as much silt as any other
exposed slope, but their erosion could cause the failure of the structural BMP.
This could easily result in the failure of the BMP to perform its task of forcing
sediment deposition to occur in a controlled location. This would leave open
19
the potential for erosive transport of soil from a much larger area than that
originally exposed on the slope of the BMP.
F. Cut and Fill Slopes (Erosion and Sediment Control Requirement
Number 5)
Newly created slopes shall be covered or otherwise protected as provided for
elsewhere in this plan.
The faces of newly created fill slopes shall be well compacted. Since it is often
impossible for typical compaction equipment to adequately compact the outer one
to three feet of a fill, it will be necessary for compaction equipment to be operated
up and down the face of the slope after the fill is completed. Operating tracked
equipment in this manner will provide a certain amount of slope roughness
which is desirable in slowing the velocity of running water and in retaining seed
and fertilizer.
After cut or fill slopes are covered, they should be monitored to ensure that the
covering is functioning as intended and that rills are not forming under or
through the covering.
G. Controlling Off-Site Erosion (Erosion and Sediment Control Require-
ment Number 6)
The BMPs specified by this plan are intended to prevent damage to downstream
and/or adjoining properties. To the extent that construction of this project is per-
formed as intended and all elements of this plan are implemented, there should
be no off-site erosion. It is possible that extensive covering of slopes and similar
practices could increase the volume of peak floods, especially if a storm event
greater than a two year event were to occur before the site were completely
revegetated and the stormwater infiltration/detention systems completed.
The possibility of this occurring increases significantly if construction is delayed
and exposed slopes must be covered through a winter rainy season instead of
having been successfully revegetated. While this is not expected to occur, it is
possible that the vagaries of the construction trade will cause this to happen. If
this does occur, downstream drainage channels shall be inspected before the end
of the Fall planting season and an inventory made of areas where increased
flows would reasonably be expected to cause erosion. Such areas shall then be
protected in a manner consistent with the goals and guidelines included within
this plan. Those BMPs noted above as being held in "ready reserve" on this proj-
ect may be brought up to active status by their use in such off-site situations.
H. Stabilization of Temporary Channels and Outlets (Erosion and Sediment
Control Requirement Number 7)
Channels, slopes, embankments, trenches, and similar areas of disturbed soil
which are required for the implementation of this erosion control plan shall be
subject to the same erosion control requirements as other portions of the project.
In addition to the general protective requirements, specific armoring methods
are included in the appropriate details.
20
I. Underground Utility Construction (Erosion and Sediment Control Re-
quirement Number 9)
Underground utility construction shall proceed subject to the following criteria.
A major source of potentially contaminated flows is from pumping or other-
wise dewatering trenches. For this reason, flows discharged from pumping or
other method of trench dewatering shall be closely monitored and, except
where there is no visible turbidity, treated as described below in the Section
titled"Dewatering Construction Sites."
Where feasible, no more than 500 feet of trench shall be opened at one time.
Where consistent with safety and space considerations, stockpiles of exca-
vated soils shall be placed on the uphill side of the trench. Any such stock-
piles shall be protected from erosion as provided for in this plan.
Trenches shall be backfilled and revegetated as soon as reasonably possible
following placement of utilities. Wherever trenches run more or less straight
up and down a slope, either the backfill shall be mounded over the trench or
waterbars or similar BMPs shall be utilized as necessary to prevent the back-
filled trench from becoming a water course. Simply covering the exposed soil
may not prevent the trench from conveying waters.
Where the upstream end of a pipe is subject to inundation, it shall be tempo-
rarily capped or plugged at the end of each day's work to prevent soil from
being washed into the pipe.
The underground utility locate service, 1-800-424-5555, shall be called a
minimum of 48 hours (2 working days) prior to beginning any excavation and
arrangements made to have all buried utilities marked.
J. Construction Access Routes (Erosion and Sediment Control Require-
ment Number 10)
It is expected that minor amounts of soil will be tracked onto paved roads, espe-
cially when unexpected circumstances such as rains and delays occur. To pre-
vent this from becoming a nuisance or source of sedimentation, the roads shall be
cleaned thoroughly at the end of each day if there is evidence of any significant
accumulation of soil. Sediment shall be removed from roads by shoveling or
sweeping and be transported to a controlled sediment disposal area. Washing of
the street shall be allowed only after sediment is removed in this manner. Wher-
ever construction, delivery, and similar vehicles enter paved roads from this
project, the following provisions shall be followed to minimize the transport of
soil onto the paved road.
During periods of dry weather (where the soil is too dry to adhere to the tires of
construction vehicles) construction vehicles may access paved streets directly
from the project site with monitoring and occasional sweeping of the paved street
as necessary to prevent accumulations of soil.
21
During periods of wet weather(where soil readily adheres to the tires of vehicles)
the vehicles may access graveled roads directly from the project site as neces-
sary, but shall not access paved roads without first having been routed over ar-
eas where existing grass or other vegetation remains or routed down a minimum
of 150 feet of graveled road. Access routes over grass or other vegetation shall be
changed occasionally to ensure that wheel ruts are not allowed to develop and
that the vegetation is not unduly worn down.
K. Removal of Temporary BMPs (Erosion and Sediment Control Require-
ment Number 11)
Temporary Erosion Control Facilities shall be promptly (within 60 days) re-
moved, once their presence is no longer required. During their removal, any en-
trapped sediment shall be disposed of in suitable locations on the project site
where they will not be subject to erosion. Disturbed areas left after the removal
of sediments shall be promptly stabilized.
As an alternate to the removal of entrapped sediments, they may be stabilized in
place by the application of suitable BMPs such as sodding, mulching, seeding,
etc.
In no case shall sediments be left in a channel or where they would be washed
into receiving waters by the next storm. The role of the Erosion Control Facili-
ties is to prevent sediments from entering waters, not to merely delay it until af-
ter construction is completed.
L. Dewatering Construction Sites (Erosion and Sediment Control Require-
ment Number 12)
Discharges from pumps used in dewatering trenches or other portions of a con-
struction site shall be dispersed by one of the following methods:
Directing flows onto existing heavily vegetated areas. If this is done, the
flows shall be directed against objects such as old tires or stumps, capable of
disrupting concentrated flows.
Directing flows onto a pad constructed of clean, pit run gravel or washed
drain rock or pea gravel. The pad shall be a minimum of 15 feet square and
flows shall be directed into a circle of 6 - 8 inch diameter stones to assist in
dispersing flows into sheet flows.
Directing flows directly into a grassy swale or other sediment trapping BMP,
constructed per this plan.
In no case shall flows discharged from a pump be allowed to remain as a concen-
trated flow. Every effort shall be made to break the flows into sheet flows.
22
In all cases, flows from dewatering shall be routed through a sediment trapping
BMP before being released off of the site.
M. Control of Pollutants Other than Sediment (Erosion and Sediment Con-
trol Requirement Number 13)
All potential pollutants other than sediments that may occur on the site during
the construction process shall be handled and disposed of in a manner that does
not cause contamination of stormwater.
1. Control of Toxic Substances
No toxic or noxious substances shall be used, stored or disposed of on or off
the project site in conjunction with the project except in full compliance with
all applicable federal, state and local laws and regulations and the recom-
mendations of the supplier of the substance. The product label or instruc-
tions for use and the Material Safety Data Sheets (MSDS) for such products
shall be kept on the site until the product has been used up or removed from
the site and properly disposed of.
While not commonly thought of as a hazardous material, common fertilizer
can be very damaging if allowed to enter receiving waters. Fertilizers shall
only be used in accordance with the recommendations of the supplier and any
concentrations such as dribbles or leaks shall be cleaned up.
In the event of a spill or other unusual event involving toxic or hazardous
materials, work in the vicinity shall be immediately stopped and the follow-
ing agencies notified:
Washington State Department of Ecology, (206) 459-6000 during normal
business hours or(206) 753-2353 after hours.
If the incident presents a threat to life, health, or property, the Fire and Po-
lice Departments shall be notified by dialing 911.
2. Petroleum Spills
The following requirements are included to ensure compliance with Part 40 of
CFR 112 in cases where SPCC Plans are required. They shall be followed on
all projects.
Storage of fuel for construction vehicles and fueling of construction vehicles
shall be performed in accordance with the following requirements:
a. Driver Training
All employees assigned to operate fuel trucks will be properly trained in
appropriate regulations and safety procedures. Training shall include
23
proper inspection and use of tanks, hatches, valves, pumps, hoses and fuel
delivery equipment.
b. Fueling of Vehicles
Fuel nozzles shall be locked when not attended and hoses shall be re-
wound or otherwise properly stored when not in use. Unattended fueling
which relies on the proper operation of automatic shutoff nozzles shall not
be permitted.
c. Parking of Fuel Tankers
Parking areas for fuel trucks shall be selected such that spills will not
leave the area. Fuel trucks shall not be parked closer than 25 feet to a
conveyance BMP such as a grassy swale or interceptor swale. When fuel
trucks must be taken to other portions of the project to fuel equipment,
they must be continuously attended or returned to the staging/storage
area. Fuel trucks shall be locked with the wheels chocked when unat-
tended and not in use.
d. Containment of Spills
Spills shall be immediately diked and every effort made to stop spillage.
Each fuel truck shall carry a long handled shovel for use in containing
spills. In the event of a spill, the U. S. Environmental Protection Agency,
Seattle, Washington (206) 442-1263, shall be notified as soon as possible.
If the magnitude of the spill is such that it presents an immediate threat
to life, health, or property, it shall be promptly reported by dialing 911.
N. Maintenance (Erosion and Sediment Control Requirement Number 14)
This section constitutes the Operation and Maintenance Manual for the erosion
and sediment control BMPs used during the construction phase of this project.
Most of the various BMPs required to maintain water quality during the con-
struction phase of this project are of a temporary nature. They are neither in-
tended nor expected to remain in service for months at a time. The typical BMP
often has a life expectancy of only 6 - 12 weeks unless time and effort are ex-
pended to bring it back to its original condition.
Foul weather, rough use, overloading and similar conditions will reduce the life
of these items. It is critical that all of the erosion and sediment control BMPs be
maintained in their intended condition until they have served their purpose and
are ready to be removed.
The project foreman shall inspect the various parts of the system at least once
daily during rainy weather. In addition, the foreman shall perform additional
inspections during or immediately after significant rainfall. Any damaged or
non-functioning components of the system shall be repaired before noon of the
next day.
24
In addition to verifying that the various BMPs are functioning as intended, the
foreman shall check for formation of rills, deposits of silt and similar indications
that the system is not functioning properly. If it is found that the system is not
performing its role in preventing erosion and sedimentation, additional BMPs
shall be provided as necessary.
Specific maintenance instructions for the various erosion and sediment control
BMPs are contained in the DOE Manual.
O. Financial Liability
Construction, operation, maintenance, replacement, and final removal of the ero-
sion and sedimentation control BMPs is an integral part of the construction of
this project. When referenced as such by the construction contract or similar
documents, this plan forms a part of the construction plans for this project. In
such cases the erosion and sedimentation control work is covered under applica-
ble financial instruments such as the contractor's and developer's bonds to the
same extent as all other items of work shown in the construction plans.
25
APPENDIX I
Subsection 1
Summary of various coefficients and operational values for the site.
PROJECT: Ramey Drainage
BASIN DATA
Predevelopment
Undetained Detained Total
Area: 0.3200 (Ac) + 0.0000 (Ac) = 0.3200 (Ac)
Cn: 76.0 100.0
Tc: 47 (min) 47 (min)
Postdevelopment Basin Data
Undetained Detained Total
Area: 0.2626 (Ac) + 0.0574 (Ac) = 0.3200 (Ac)
Cn: 85.3 98.0
Tc: 27 (min) 27 (min)
RAINFALL
Peak
24 hr rainfall depth Basin Rainfall
(Qr)
2 yr storm: 1.20 (in) 0.1255 (cfs)
25 yr storm: 2.20 (in) 0.2300 (cfs)
100 yr storm: 2.70 (in) 0.2823 (cfs)
PREDEVELOPMENT RUNOFF
Peak
Pre-Devt Runoff
(Qpre)
2 yr storm: 0.0025 (cfs)
25 yr storm: 0.0119 (cfs)
100 yr storm: 0.0242 (cfs)
POSTDEVELOPMENT RUNOFF
Peak Runoff From Peak Runoff From
Undeveloped Port'n Developed Port'n
(Undetained) (Detained)
(Qposl) (Qpos2)
2 yr storm: 0.0067 (cfs) 0.0113 (cfs)
25 yr storm: 0.0404 (cfs) 0.0224 (cfs)
100 yr storm: 0.0616 (cfs) 0.0278 (cfs)
Peak
Runoff From
Entire Basin
(Qpos)
2 yr storm: 0.0174 (cfs)
25 yr storm: 0.0627 (cfs)
100 yr storm: 0.0895 (cfs)
APPENDIX I
Subsection 2
Catalog of pre- and post-development land uses.
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a m 0 0,0 a a H-I rom N 0,0 a a 0
0 m 0 •0 a) 0 m O '0 a)
v '0 £q >,oca. 0 i 0 a) '0 0 >.o q 1.1 v
'0 m 0 0 m m 0 -N L '0
w U m a .q3S m H. -0 -01 ..1 a m 4 a 3 a 0) o
a 13 N 00 N m -14 0 m 3 CL 0 0 m 3-.4 5 6 3 0
0. a 2D. agx a a 010. POx 04
APPENDIX I
Subsection 3
Raw rainfall data for the design storms falling on the site.
PROJECT: Ramey Drainage
25 yr storm (B)
Total Basin Area = 13939 sq ft = 0.3200 Ac
Storm Duration = 24 hr
Peak Rainfall Intensity = 0.230 cfs
Total Rainfall Volume = 2556 cu ft
Total, 24 hr rainfall = 2.20 in
Rainfall Data
Standard SCS Type lA
24 hr hyetograph (adj 'd) Total Cumulative
from King Co Drn Manual Basin Precip Precip
Rainfall Depth Depth
Time % Cumulative Time P Pr Prc
(min) Precip o Precip (hrs) (cfs) (in) (in)
0 0.00 0.00 0.00 0.0000 0.0000 0.0000
10 0.40 0.40 0.17 0.0170 0.0088 0.0088
20 0.40 0.80 0.33 0.0170 0.0088 0.0176
30 0.40 1.20 0.50 0.0170 0.0088 0.0264
40 0.40 1.60 0.67 0.0170 0.0088 0.0352
50 0.40 2.00 0.83 0.0170 0.0088 0.0440
60 0.40 2.40 1.00 0.0170 0.0088 0.0528
70 0.40 2.80 1.17 0.0170 0.0088 0.0616
80 0.40 3.20 1.33 0.0170 0.0088 0.0704
90 0.40 3 .60 1.50 0.0170 0.0088 0.0792
100 0.40 4.00 1.67 0.0170 0.0088 0.0880
110 0.50 4.50 1.83 0.0213 0.0110 0.0990
120 0.50 5.00 2.00 0.0213 0.0110 0.1100
130 0.50 5.50 2.17 0.0213 0.0110 0.1210
140 0.50 6.00 2.33 0.0213 0.0110 0.1320
150 0.50 6.50 2.50 0.0213 0.0110 0.1430
160 0.50 7.00 2.67 0.0213 0.0110 0.1540
170 0.60 7.60 2.83 0.0256 0.0132 0.1672
180 0.60 8.20 3 .00 0.0256 0.0132 0.1804
190 0.60 8.80 3 .17 0.0256 0.0132 0.1936
200 0.60 9.40 3 .33 0.0256 0.0132 0.2068
210 0.60 10.00 3 .50 0.0256 0.0132 0.2200
220 0.60 10.60 3 .67 0.0256 0.0132 0.2332
230 0.70 11.30 3.83 0.0298 0.0154 0.2486
240 0.70 12.00 4.00 0.0298 0.0154 0.2640
250 0.70 12.70 4.17 0.0298 0.0154 0.2794
260 0.70 13.40 4.33 0.0298 0.0154 0.2948
270 0.70 14.10 4.50 0.0298 0.0154 0.3102
280 0.70 14.80 4.67 0.0298 0.0154 0.3256
290 0.82 15.62 4.83 0.0349 0.0180 0.3436
300 0.82 16.44 5.00 0.0349 0.0180 0.3617
310 0.82 17.26 5.17 0.0349 0.0180 0.3797
320 0.82 18.08 5.33 0.0349 0.0180 0.3978
330 0.82 18.90 5.50 0.0349 0.0180 0.4158
340 0.82 19.72 5.67 0.0349 0.0180 0.4338
350 0.95 20.67 5.83 0.0405 0.0209 0.4547
360 0.95 21.62 6.00 0.0405 0.0209 0.4756
370 0.95 22.57 6.17 0.0405 0.0209 0.4965
380 0.95 23 .52 6.33 0.0405 0.0209 0.5174
PROJECT: Ramey Drainage
25 yr storm (B)
Total Basin Area = 13939 sq ft = 0.3200 Ac
Storm Duration = 24 hr
Peak Rainfall Intensity = 0.230 cfs
Total Rainfall Volume = 2556 cu ft
Total, 24 hr rainfall = 2.20 in
Rainfall Data
Standard SCS Type lA
24 hr hyetograph (adj 'd) Total Cumulative
from King Co Drn Manual Basin Precip Precip
Rainfall Depth Depth
Time % Cumulative Time P Pr Prc
(min) Precip % Precip (hrs) (cfs) (in) (in)
390 0.95 24.47 6.50 0.0405 0.0209 0.5383
400 0.95 25.42 6.67 0.0405 0.0209 0.5592
410 1.33 26.75 6.83 0.0566 0.0293 0.5885
420 1.33 28.08 7.00 0.0566 0.0293 0.6178
430 1.33 29.41 7.17 0.0566 0.0293 0.6470
440 1.80 31.21 7.33 0.0767 0.0396 0.6866
450 1.80 33 .01 7.50 0.0767 0.0396 0.7262
460 3.40 36.41 7.67 0.1448 0.0748 0.8010
470 5.40 41.81 7.83 0.2300 0.1188 0.9198
480 2.70 44.51 8.00 0.1150 0.0594 0.9792
490 1.80 46.31 8.17 0.0767 0.0396 1.0188
500 1.34 47.65 8.33 0.0571 0.0295 1.0483
510 1.34 48.99 8.50 0.0571 0.0295 1.0778
520 1.34 50.33 8.67 0.0571 0.0295 1.1073
530 0.88 51.21 8.83 0.0375 0.0194 1.1266
540 0.88 52.09 9.00 0.0375 0.0194 1.1460
550 0.88 52.97 9.17 0.0375 0.0194 1.1653
560 0.88 53.85 9.33 0.0375 0.0194 1.1847
570 0.88 54.73 9.50 0.0375 0.0194 1.2041
580 0.88 55.61 9.67 0.0375 0.0194 1.2234
590 0.88 56.49 9.83 0.0375 0.0194 1.2428
600 0.88 57.37 10.00 0.0375 0.0194 1.2621
610 0.88 58.25 10.17 0.0375 0.0194 1.2815
620 0.88 59.13 10.33 0.0375 0.0194 1.3009
630 0.88 60.01 10.50 0.0375 0.0194 1.3202
640 0.88 60.89 10.67 0.0375 0.0194 1.3396
650 0.72 61.61 10.83 0.0307 0.0158 1.3554
660 0.72 62.33 11.00 0.0307 0.0158 1.3713
670 0.72 63.05 11.17 0.0307 0.0158 1.3871
680 0.72 63.77 11.33 0.0307 0.0158 1.4029
690 0.72 64.49 11.50 0.0307 0.0158 1.4188
700 0.72 65.21 11.67 0.0307 0.0158 1.4346
710 0.72 65.93 11.83 0.0307 0.0158 1.4505
720 0.72 66.65 12 .00 0.0307 0.0158 1.4663
730 0.72 67.37 12.17 0.0307 0.0158 1.4821
740 0.72 68.09 12.33 0.0307 0.0158 1.4980
750 0.72 68.81 12.50 0.0307 0.0158 1.5138
760 0.72 69.53 12.67 0.0307 0.0158 1.5297
770 0.57 70.10 12.83 0.0243 0.0125 1.5422
PROJECT: Ramey Drainage
25 yr storm (B)
Total Basin Area = 13939 sq ft = 0.3200 Ac
Storm Duration = 24 hr
Peak Rainfall Intensity = 0.230 cfs
Total Rainfall Volume = 2556 cu ft
Total, 24 hr rainfall = 2.20 in
Rainfall Data
Standard SCS Type lA
24 hr hyetograph (adj 'd) Total Cumulative
from King Co Drn Manual Basin Precip Precip
Rainfall Depth Depth
Time % Cumulative Time P Pr Prc
(min) Precip o Precip (hrs) (cfs) (in) (in)
780 0.57 70.67 13.00 0.0243 0.0125 1.5547
790 0.57 71.24 13.17 0.0243 0.0125 1.5673
800 0.57 71.81 13 .33 0.0243 0.0125 1.5798
810 0.57 72.38 13.50 0.0243 0.0125 1.5924
820 0.57 72.95 13.67 0.0243 0.0125 1.6049
830 0.57 73.52 13.83 0.0243 0.0125 1.6174
840 0.57 74.09 14.00 0.0243 0.0125 1.6300
850 0.57 74.66 14.17 0.0243 0.0125 1.6425
860 0.57 75.23 14.33 0.0243 0.0125 1.6551
870 0.57 75.80 14.50 0.0243 0.0125 1.6676
880 0.57 76.37 14.67 0.0243 0.0125 1.6801
890 0.50 76.87 14.83 0.0213 0.0110 1.6911
900 0.50 77.37 15.00 0.0213 0.0110 1.7021
910 0.50 77.87 15.17 0.0213 0.0110 1.7131
920 0.50 78.37 15.33 0.0213 0.0110 1.7241
930 0.50 78.87 15.50 0.0213 0.0110 1.7351
940 0.50 79.37 15.67 0.0213 0.0110 1.7461
950 0.50 79.87 15.83 0.0213 0.0110 1.7571
960 0.50 80.37 16.00 0.0213 0.0110 1.7681
970 0.50 80.87 16.17 0.0213 0.0110 1.7791
980 0.50 81.37 16.33 0.0213 0.0110 1.7901
990 0.50 81.87 16.50 0.0213 0.0110 1.8011
1000 0.50 82.37 16.67 0.0213 0.0110 1.8121
1010 0.43 82.80 16.83 0.0183 0.0095 1.8216
1020 0.40 83.20 17.00 0.0170 0.0088 1.8304
1030 0.40 83 .60 17.17 0.0170 0.0088 1.8392
1040 0.40 84.00 17.33 0.0170 0.0088 1.8480
1050 0.40 84.40 17.50 0.0170 0.0088 1.8568
1060 0.40 84.80 17.67 0.0170 0.0088 1.8656
1070 0.40 85.20 17.83 0.0170 0.0088 1.8744
1080 0.40 85.60 18.00 0.0170 0.0088 1.8832
1090 0.40 86.00 18.17 0.0170 0.0088 1.8920
1100 0.40 86.40 18.33 0.0170 0.0088 1.9008
1110 0.40 86.80 18.50 0.0170 0.0088 1.9096
1120 0.40 87.20 18.67 0.0170 0.0088 1.9184
1130 0.40 87.60 18.83 0.0170 0.0088 1.9272
1140 0.40 88.00 19.00 0.0170 0.0088 1.9360
1150 0.40 88.40 19.17 0.0170 0.0088 1.9448
1160 0.40 88.80 19.33 0.0170 0.0088 1.9536
PROJECT: Ramey Drainage
25 yr storm (B)
Total Basin Area = 13939 sq ft = 0.3200 Ac
Storm Duration = 24 hr
Peak Rainfall Intensity = 0.230 cfs
Total Rainfall Volume = 2556 cu ft
Total, 24 hr rainfall = 2.20 in
Rainfall Data
Standard SCS Type lA
24 hr hyetograph (adj 'd) Total Cumulative
from King Co Drn Manual Basin Precip Precip
Rainfall Depth Depth
Time % Cumulative Time P Pr Prc
(min) Precip % Precip (hrs) (cfs) (in) (in)
1170 0.40 89.20 19.50 0.0170 0.0088 1.9624
1180 0.40 89.60 19.67 0.0170 0.0088 1.9712
1190 0.40 90.00 19.83 0.0170 0.0088 1.9800
1200 0.40 90.40 20.00 0.0170 0.0088 1.9888
1210 0.40 90.80 20.17 0.0170 0.0088 1.9976
1220 0.40 91.20 20.33 0.0170 0.0088 2.0064
1230 0.40 91.60 20.50 0.0170 0.0088 2 .0152
1240 0.40 92.00 20.67 0.0170 0.0088 2.0240
1250 0.40 92.40 20.83 0.0170 0.0088 2.0328
1260 0.40 92.80 21.00 0.0170 0.0088 2.0416
1270 0.40 93 .20 21.17 0.0170 0.0088 2.0504
1280 0.40 93.60 21.33 0.0170 0.0088 2.0592
1290 0.40 94.00 21.50 0.0170 0.0088 2.0680
1300 0.40 94.40 21.67 0.0170 0.0088 2.0768
1310 0.40 94.80 21.83 0.0170 0.0088 2 .0856
1320 0.40 95.20 22.00 0.0170 0.0088 2.0944
1330 0.40 95.60 22.17 0.0170 0.0088 2.1032
1340 0.40 96.00 22.33 0.0170 0.0088 2 .1120
1350 0.40 96.40 22.50 0.0170 0.0088 2.1208
1360 0.40 96.80 22.67 0.0170 0.0088 2 .1296
1370 0.40 97.20 22.83 0.0170 0.0088 2.1384
1380 0.40 97.60 23.00 0.0170 0.0088 2.1472
1390 0.40 98.00 23.17 0.0170 0.0088 2 .1560
1400 0.40 98.40 23.33 0.0170 0.0088 2.1648
1410 0.40 98.80 23.50 0.0170 0.0088 2.1736
1420 0.40 99.20 23 .67 0.0170 0.0088 2 .1824
1430 0.40 99.60 23.83 0.0170 0.0088 2.1912
1440 0.40 100.00 24.00 0.0170 0.0088 2.2000
1450 0.00 100.00 24.17 0.0000 0.0000 2 .2000
1460 0.00 100.00 24 .33 0.0000 0.0000 2.2000
1470 0.00 100.00 24.50 0.0000 0.0000 2.2000
1480 0.00 100.00 24.67 0.0000 0.0000 2 .2000
1490 0.00 100.00 24.83 0.0000 0.0000 2 .2000
1500 0.00 100.00 25.00 0.0000 0.0000 2 .2000
100.00 2.2000
APPENDIX I
Subsection 4
Pre-development runoff calculations for the design storms.
PROJECT: Ramey Drainage
Generation of Predevelopment Runoff Hydrograph - Santa Barbara Urban Hydrograph Method
25 yr storm (A) Qpeak = 0.0119 cfs
Vtotal = 597 cu ft
Pervious Portion of Basin Impervious Portion of Basin
Pervious Area = 13939.2 sq ft Impervious Area = 0 sq ft
= 0.3200 Ac = 0.0000 Ac
Runoff Curve Number, Cu = 76 Runoff Curve Number, Cn = 100
Time of Concentrat'n, Tc = 47 min Time of Concentrat'n, Tc = 47 min
Pot'l Max Nat'l Det'n, S = 3.1579 in Pot'l Max Nat'l Det'n, S = 0.0000 in
Routing Coefficient, w = 0.0962 Routing Coefficient, w = 0.0962
Cumulative Cumulative
Cumulative Instan- Instan- Cumulative Instan- Instan-
Excess Excess taneous taneous Routed Excess Excess taneous taneous Routed Total
Precip Precip Runoff Runoff Runoff Precip Precip Runoff Runoff Runoff Runoff
Time R Rc Qi Vc Qr R Rc Qi Vc Qr
4
(hrs) (in) (in) (cfs) (cu ft) (cfs) (in) (in) (cfs) (cu ft) (cfs) (cfs)
[0.00] 0.0000 0.0000 0.0000 0 0.0000 0.0000 0.0000 0.0000 0 0.0000 0.0000
[0.17] 0.0000 0.0000 0.0000 0 0.0000 0.0088 0.0088 0.0000 0 0.0000 0.0000
[0.33] 0.0000 0.0000 0.0000 0 0.0000 0.0088 0.0176 0.0000 0 0.0000 0.0000
[0.50] 0.0000 0.0000 0.0000 0 0.0000 0.0088 0.0264 0.0000 0 0.0000 0.0000
[0.67] 0.0000 0.0000 0.0000 0 0.0000 0.0088 0.0352 0.0000 0 0.0000 0.0000
[0.83] 0.0000 0.0000 0.0000 0 0.0000 0.0088 0.0440 0.0000 0 0.0000 0.0000
[1.00) 0.0000 0.0000 0.0000 0 0.0000 0.0088 0.0528 0.0000 0 0.0000 0.0000
[1.17] 0.0000 0.0000 0.0000 0 0.0000 0.0088 0.0616 0.0000 0 0.0000 0.0000
[1.33] 0.0000 0.0000 0.0000 0 0.0000 0.0088 0.0704 0.0000 0 0.0000 0.0000
[1.50] 0.0000 0.0000 0.0000 0 0.0000 0.0088 0.0792 0.0000 0 0.0000 0.0000
[1.67] 0.0000 0.0000 0.0000 0 0.0000 0.0088 0.0880 0.0000 0 0.0000 0.0000
[1.83] 0.0000 0.0000 0.0000 0 0.0000 0.0110 0.0990 0.0000 0 0.0000 0.0000
[2.00] 0.0000 0.0000 0.0000 0 0.0000 0.0110 0.1100 0.0000 0 0.0000 0.0000
[2.17] 0.0000 0.0000 0.0000 0 0.0000 0.0110 0.1210 0.0000 0 0.0000 0.0000
[2.33] 0.0000 0.0000 0.0000 0 0.0000 0.0110 0.1320 0.0000 0 0.0000 0.0000
[2.50] 0.0000 0.0000 0.0000 0 0.0000 0.0110 0.1430 0.0000 0 0.0000 0.0000
[2.67] 0.0000 0.0000 0.0000 0 0.0000 0.0110 0.1540 0.0000 0 0.0000 0.0000
[2.83] 0.0000 0.0000 0.0000 0 0.0000 0.0132 0.1672 0.0000 0 0.0000 0.0000
[3.00] 0.0000 0.0000 0.0000 0 0.0000 0.0132 0.1804 0.0000 0 0.0000 0.0000
[3.17] 0.0000 0.0000 0.0000 0 0.0000 0.0132 0.1936 0.0000 0 0.0000 0.0000
[3.33] 0.0000 0.0000 0.0000 0 0.0000 0.0132 0.2068 0.0000 0 0.0000 0.0000
[3.50] 0.0000 0.0000 0.0000 0 0.0000 0.0132 0.2200 0.0000 0 0.0000 0.0000
[3.67] 0.0000 0.0000 0.0000 0 0.0000 0.0132 0.2332 0.0000 0 0.0000 0.0000
[3.83] 0.0000 0.0000 0.0000 0 0.0000 0.0154 0.2486 0.0000 0 0.0000 0.0000
[4.00] 0.0000 0.0000 0.0000 0 0.0000 0.0154 0.2640 0.0000 0 0.0000 0.0000
[4.17] 0.0000 0.0000 0.0000 0 0.0000 0.0154 0.2794 0.0000 0 0.0000 0.0000
[4.33] 0.0000 0.0000 0.0000 0 0.0000 0.0154 0.2948 0.0000 0 0.0000 0.0000
[4.50] 0.0000 0.0000 0.0000 0 0.0000 0.0154 0.3102 0.0000 0 0.0000 0.0000
[4.67] 0.0000 0.0000 0.0000 0 0.0000 0.0154 0.3256 0.0000 0 0.0000 0.0000
[4.83] 0.0000 0.0000 0.0000 0 0.0000 0.0180 0.3436 0.0000 0 0.0000 0.0000
[5.00] 0.0000 0.0000 0.0000 0 0.0000 0.0180 0.3617 0.0000 0 0.0000 0.0000
[5.17] 0.0000 0.0000 0.0000 0 0.0000 0.0180 0.3797 0.0000 0 0.0000 0.0000
[5.33] 0.0000 0.0000 0.0000 0 0.0000 0.0180 0.3978 0.0000 0 0.0000 0.0000
[5.50] 0.0000 0.0000 0.0000 0 0.0000 0.0180 0.4158 0.0000 0 0.0000 0.0000
[5.67] 0.0000 0.0000 0.0000 0 0.0000 0.0180 0.4338 0.0000 0 0.0000 0.0000
[5.83] 0.0000 0.0000 0.0000 0 0.0000 0.0209 0.4547 0.0000 0 0.0000 0.0000
[6.00] 0.0000 0.0000 0.0000 0 0.0000 0.0209 0.4756 0.0000 0 0.0000 0.0000
[6.17] 0.0000 0.0000 0.0000 0 0.0000 0.0209 0.4965 0.0000 0 0.0000 0.0000
[6.33] 0.0000 0.0000 0.0000 0 0.0000 0.0209 0.5174 0.0000 0 0.0000 0.0000
[6.50] 0.0000 0.0000 0.0000 0 0.0000 0.0209 0.5383 0.0000 0 0.0000 0.0000
[6.67] 0.0000 0.0000 0.0000 0 0.0000 0.0209 0.5592 0.0000 0 0.0000 0.0000
[6.83] 0.0000 0.0000 0.0000 0 0.0000 0.0293 0.5885 0.0000 0 0.0000 0.0000
[7.00] 0.0000 0.0000 0.0000 0 0.0000 0.0293 0.6178 0.0000 0 0.0000 0.0000
[7.17] 0.0001 0.0001 0.0001 0 0.0000 0.0293 0.6470 0.0000 0 0.0000 0.0000
[7.33] 0.0009 0.0009 0.0017 1 0.0002 0.0396 0.6866 0.0000 0 0.0000 0.0002
[7.50] 0.0018 0.0028 0.0035 3 0.0006 0.0396 0.7262 0.0000 0 0.0000 0.0006
[7.67] 0.0059 0.0086 0.0114 10 0.0020 0.0748 0.8010 0.0000 0 0.0000 0.0020
[7.83] 0.0155 0.0241 0.0300 28 0.0056 0.1188 0.9198 0.0000 0 0.0000 0.0056
[8.00) 0.0104 0.0345 0.0201 40 0.0093 0.0594 0.9792 0.0000 0 0.0000 0.0093
[8.17] 0.0078 0.0423 0.0151 49 0.0109 0.0396 1.0188 0.0000 0 0.0000 0.0109
[8.33] 0.0063 0.0486 0.0122 56 0.0114 0.0295 1.0483 0.0000 0 0.0000 0.0114
[8.50) 0.0067 0.0552 0.0129 64 0.0116 0.0295 1.0778 0.0000 0 0.0000 0.0116
[8.67] 0.0070 0.0623 0.0136 72 0.0119 0.0295 1.1073 0.0000 0 0.0000 0.0119
[8.83] 0.0048 0.0671 0.0093 78 0.0119 0.0194 1.1266 0.0000 0 0.0000 0.0119
[9.00] 0.0050 0.0721 0.0096 84 0.0114 0.0194 1.1460 0.0000 0 0.0000 0.0114
[9.17] 0.0051 0.0772 0.0099 90 0.0111 0.0194 1.1653 0.0000 0 0.0000 0.0111
[9.33) 0.0053 0.0824 0.0102 96 0.0109 0.0194 1.1847 0.0000 0 0.0000 0.0109
PROJECT: Ramey Drainage
Generation of Predevelopment Runoff Hydrograph - Santa Barbara Urban Hydrograph Method •
25 yr storm (A) Qpeak = 0.0119 cfs
Vtotal = 597 cu ft
Pervious Portion of Basin Impervious Portion of Basin
Pervious Area = 13939.2 sq ft Impervious Area = 0 sq ft
= 0.3200 Ac 0.0000 Ac
Runoff Curve Number, Cn = 76 Runoff Curve Number, Cn = 100
Time of Concentrat'n, Tc = 47 min Time of Concentrat'n, Tc = 47 min
Pot'l Max Nat'l Det'n, S = 3.1579 in Pot'l Max Nat'l Det'n, S - 0.0000 in
Routing Coefficient, w = 0.0962 Routing Coefficient, w = 0.0962
Cumulative Cumulative
Cumulative Instan- Instan- Cumulative Instan- Instan-
Excess Excess taneous taneous Routed Excess Excess taneous taneous Routed Total
Precip Precip Runoff Runoff Runoff Precip Precip Runoff Runoff Runoff Runoff
Time R Rc Qi Vc Qr R Rc Qi Vc Qr Q
(hrs) (in) (in) (cfs) (cu ft) (cfs) (in) (in) (cfs) (cu ft) (cfs) (cfs)
(9.50) 0.0054 0.0879 0.0105 102 0.0108 0.0194 1.2041 0.0000 0 0.0000 0.0108
[9.67] 0.0056 0.0934 0.0108 109 0.0107 0.0194 1.2234 0.0000 0 0.0000 0.0107
(9.83] 0.0057 0.0991 0.0110 115 0.0108 0.0194 1.2428 0.0000 0 0.0000 0.0108
(10.00] 0.0058 0.1050 0.0113 122 0.0109 0.0194 1.2621 0.0000 0 0.0000 0.0109
(10.17] 0.0060 0.1109 0.0116 129 0.0110 0.0194 1.2815 0.0000 0 0.0000 0.0110
[10.33] 0.0061 0.1170 0.0118 136 0.0111 0.0194 1.3009 0.0000 0 0.0000 0.0111
[10.50] 0.0062 0.1233 0.0121 143 0.0113 0.0194 1.3202 0.0000 0 0.0000 0.0113
[10.67] 0.0064 0.1297 0.0123 151 0.0115 0.0194 1.3396 0.0000 0 0.0000 0.0115
(10.83] 0.0053 0.1350 0.0103 157 0.0114 0.0158 1.3554 0.0000 0 0.0000 0.0114
[11.00] 0.0054 0.1404 0.0105 163 0.0112 0.0158 1.3713 0.0000 0 0.0000 0.0112
[11.17] 0.0055 0.1459 0.0106 169 0.0111 0.0158 1.3871 0.0000 0 0.0000 0.0111
(11.33] 0.0056 0.1514 0.0108 176 0.0110 0.0158 1.4029 0.0000 0 0.0000 0.0110
[11.50] 0.0056 0.1571 0.0109 182 0.0110 0.0158 1.4188 0.0000 0 0.0000 0.0110
[11.67] 0.0057 0.1628 0.0111 189 0.0110 0.0158 1.4346 0.0000 0 0.0000 0.0110
(11.83] 0.0058 0.1686 0.0113 196 0.0110 0.0158 1.4505 0.0000 0 0.0000 0.0110
[12.00] 0.0059 0.1745 0.0114 203 0.0111 0.0158 1.4663 0.0000 0 0.0000 0.0111
[12.17] 0.0060 0.1805 0.0116 210 0.0112 0.0158 1.4821 0.0000 0 0.0000 0.0112
[12.33] 0.0060 0.1865 0.0117 217 0.0113 0.0158 1.4980 0.0000 0 0.0000 0.0113
[12.50] 0.0061 0.1927 0.0119 224 0.0114 0.0158 1.5138 0.0000 0 0.0000 0.0114
[12.67] 0.0062 0.1989 0.0120 231 0.0115 0.0158 1.5297 0.0000 0 0.0000 0.0115
[12.83] 0.0050 0.2038 0.0096 237 0.0113 0.0125 1.5422 0.0000 0 0.0000 0.0113
[13.00] 0.0050 0.2088 0.0097 243 0.0110 0.0125 1.5547 0.0000 0 0.0000 0.0110
[13.17] 0.0051 0.2139 0.0098 248 0.0108 0.0125 1.5673 0.0000 0 0.0000 0.0108
[13.33] 0.0051. 0.2190 0.0099 254 0.0106 0.0125 1.5798 0.0000 0 0.0000 0.0106
[13.50] 0.0051 0.2241 0.0100 260 0.0105 0.0125 1.5924 0.0000 0 0.0000 0.0105
[13.67] 0.0052 0.2293 0.0100 266 0.0104 0.0125 1.6049 0.0000 0 0.0000 0.0104
[13.83] 0.0052 0.2346 0.0101 272 0.0103 0.0125 1.6174 0.0000 0 0.0000 0.0103
[14.00] 0.0053 0.2398 0.0102 279 0.0103 0.0125 1.6300 0.0000 0 0.0000 0.0103
[14.17] 0.0053 0.2452 0.0103 285 0.0103 0.0125 1.6425 0.0000 0 0.0000 0.0103
[14.33] 0.0054 0.2505 0.0104 291 0.0103 0.0125 1.6551 0.0000 0 0.0000 0.0103
[14.50] 0.0054 0.2559 0.0105 297 0.0103 0.0125 1.6676 0.0000 0 0.0000 0.0103
[14.67] 0.0055 0.2614 0.0106 304 0.0104 0.0125 1.6801 0.0000 0 0.0000 0.0104
(14.83] 0.0048 0.2662 0.0093 309 0.0103 0.0110 1.6911 0.0000 0 0.0000 0.0103
[15.00] 0.0048 0.2710 0.0094 315 0.0101 0.0110 1.7021 0.0000 0 0.0000 0.0101
[15.17] 0.0049 0.2759 0.0094 321 0.0100 0.0110 1.7131 0.0000 0 0.0000 0.0100
[15.33] 0.0049 0.2808 0.0095 326 0.0099 0.0110 1.7241 0.0000 0 0.0000 0.0099
[15.50] 0.0049 0.2858 0.0096 332 0.0098 0.0110 1.7351 0.0000 0 0.0000 0.0098
[15.67] 0.0050 0.2908 0.0096 338 0.0098 0.0110 1.7461 0.0000 0 0.0000 0.0098
(15.83] 0.0050 0.2958 0.0097 344 0.0097 0.0110 1.7571 0.0000 0 0.0000 0.0097
[16.00] 0.0050 0.3008 0.0098 349 0.0097 0.0110 1.7681 0.0000 0 0.0000 0.0097
(16.17] 0.0051 0.3059 0.0098 355 0.0098 0.0110 1.7791 0.0000 0 0.0000 0.0098
(16.33] 0.0051 0.3110 0.0099 361 0.0098 0.0110 1.7901 0.0000 0 0.0000 0.0098
[16.50] 0.0051 0.3161 0.0099 367 0.0098 0.0110 1.8011 0.0000 0 0.0000 0.0098
[16.67] 0.0052 0.3212 0.0100 373 0.0098 0.0110 1.8121 0.0000 0 0.0000 0.0098
[16.83] 0.0045 0.3257 0.0086 378 0.0097 0.0095 1.8216 0.0000 0 0.0000 0.0097
(17.00] 0.0042 0.3299 0.0081 383 0.0095 0.0088 1.8304 0.0000 0 0.0000 0.0095
[17.17] 0.0042 0.3341 0.0081 388 0.0092 0.0088 1.8392 0.0000 0 0.0000 0.0092
[17.33] 0.0042 0.3383 0.0081 393 0.0090 0.0088 1.8480 0.0000 0 0.0000 0.0090
[17.50] 0.0042 0.3425 0.0082 398 0.0088 0.0088 1.8568 0.0000 0 0.0000 0.0088
(17.67] 0.0042 0.3467 0.0082 403 0.0087 0.0088 1.8656 0.0000 0 0.0000 0.0087
[17.83] 0.0043 0.3510 0.0082 408 0.0086 0.0088 1.8744 0.0000 0 0.0000 0.0086
[18.00] 0.0043 0.3553 0.0083 413 0.0085 0.0088 1.8832 0.0000 0 0.0000 0.0085
[18.17] 0.0043 0.3596 0.0083 418 0.0085 0.0088 1.8920 0.0000 0 0.0000 0.0085
[18.33] 0.0043 0.3639 0.0084 423 0.0085 0.0088 1.9008 0.0000 0 0.0000 0.0085
[18.50] 0.0043 0.3682 0.0084 428 0.0084 0.0088 1.9096 0.0000 0 0.0000 0.0084
[18.67] 0.0043 0.3726 0.0084 433 0.0084 0.0088 1.9184 0.0000 0 0.0000 0.0084
[18.83] 0.0044 0.3769 0.0085 438 0.0084 0.0088 1.9272 0.0000 0 0.0000 0.0084
PROJECT: Ramey Drainage
Generation of Predevelopment Runoff Hydrograph - Santa Barbara Urban Hydrograph Method
25 yr storm (A) Qpeak = 0.0119 cfs
Vtotal = 597 cu ft
Pervious Portion of Basin Impervious Portion of Basin
Pervious Area = 13939.2 sq ft Impervious Area = 0 sq ft
= 0.3200 Ac = 0.0000 Ac
Runoff Curve Number, Cn = 76 Runoff Curve Number, Cn = 100
Time of Concentrat'n, Tc = 47 min Time of Concentrat'n, Tc = 47 min
Pot'l Max Nat'l Det'n, S = 3.1579 in Pot'l Max Nat'l Det'n, S = 0.0000 in
Routing Coefficient, w = 0.0962 Routing Coefficient, w = 0.0962
Cumulative Cumulative
Cumulative Instan- Instan- Cumulative Instan- Instan-
Excess Excess taneous taneous Routed Excess Excess taneous taneous Routed Total
Precip Precip Runoff Runoff Runoff Precip Precip Runoff Runoff Runoff Runoff
Time R Rc Qi Vc Qr R Rc Qi Vc Qr Q
(hrs) (in) (in) (cfs) (cu ft) (cfs) (in) (in) (cfs) (cu ft) (cfs) (cfs)
[19.00] 0.0044 0.3813 0.0085 443 0.0084 0.0088 1.9360 0.0000 0 0.0000 0.0084
[19.17] 0.0044 0.3857 0.0085 448 0.0085 0.0088 1.9448 0.0000 0 0.0000 0.0085
[19.33] 0.0044 0.3901 0.0086 453 0.0085 0.0088 1.9536 0.0000 0 0.0000 0.0085
[19.50] 0.0044 0.3946 0.0086 458 0.0085 0.0088 1.9624 0.0000 0 0.0000 0.0085
[19.67] 0.0045 0.3990 0.0086 463 0.0085 0.0088 1.9712 0.0000 0 0.0000 0.0085
[19.83] 0.0045 0.4035 0.0087 469 0.0085 0.0088 1.9800 0.0000 0 0.0000 0.0085
[20.00] 0.0045 0.4080 0.0087 474 0.0086 0.0088 1.9888 0.0000 0 0.0000 0.0086
[20.17] 0.0045 0.4125 0.0087 479 0.0086 0.0088 1.9976 0.0000 0 0.0000 0.0086
[20.33] 0.0045 0.4170 0.0088 484 0.0086 0.0088 2.0064 0.0000 0 0.0000 0.0086
[20.50] 0.0045 0.4215 0.0088 490 0.0086 0.0088 2.0152 0.0000 0 0.0000 0.0086
[20.67] 0.0046 0.4261 0.0088 495 0.0087 0.0088 2.0240 0.0000 0 0.0000 0.0087
[20.83] 0.0046 0.4307 0.0088 500 0.0087 0.0088 2.0328 0.0000 0 0.0000 0.0087
[21.00] 0.0046 0.4352 0.0089 506 0.0087 0.0088 2.0416 0.0000 0 0.0000 0.0087
[21.17] 0.0046 0.4398 0.0089 511 0.0088 0.0088 2.0504 0.0000 0 0.0000 0.0088
[21.33] 0.0046 0.4445 0.0089 516 0.0088 0.0088 2.0592 0.0000 0 0.0000 0.0088
[21.50] 0.0046 0.4491 0.0090 522 0.0088 0.0088 2.0680 0.0000 0 0.0000 0.0088
[21.67] 0.0047 0.4538 0.0090 527 0.0089 0.0088 2.0768 0.0000 0 0.0000 0.0089
[21.83] 0.0047 0.4584 0.0090 532 0.0089 0.0088 2.0856 0.0000 0 0.0000 0.0089
[22.00] 0.0047 0.4631 0.0091 538 0.0089 0.0088 2.0944 0.0000 0 0.0000 0.0089
[22.17] 0.0047 0.4678 0.0091 543 0.0090 0.0088 2.1032 0.0000 0 0.0000 0.0090
[22.33] 0.0047 0.4725 0.0091 549 0.0090 0.0088 2.1120 0.0000 0 0.0000 0.0090
[22.50] 0.0047 0.4772 0.0092 554 0.0090 0.0088 2.1208 0.0000 0 0.0000 0.0090
[22.67] 0.0047 0.4820 0.0092 560 0.0090 0.0088 2.1296 0.0000 0 0.0000 0.0090
[22.83] 0.0048 0.4867 0.0092 565 0.0091 0.0088 2.1384 0.0000 0 0.0000 0.0091
[23.00] 0.0048 0.4915 0.0092 571 0.0091 0.0088 2.1472 0.0000 0 0.0000 0.0091
[23.17] 0.0048 0.4963 0.0093 577 0.0091 0.0088 2.1560 0.0000 0 0.0000 0.0091
[23.33] 0.0048 0.5011 0.0093 582 0.0092 0.0088 2.1648 0.0000 0 0.0000 0.0092
[23.50) 0.0048 0.5059 0.0093 588 0.0092 0.0088 2.1736 0.0000 0 0.0000 0.0092
[23.67] 0.0048 0.5108 0.0094 593 0.0092 0.0088 2.1824 0.0000 0 0.0000 0.0092
[23.83] 0.0048 0.5156 0.0094 599 0.0093 0.0088 2.1912 0.0000 0 0.0000 0.0093
[24.00] 0.0049 0.5205 0.0094 605 0.0093 0.0088 2.2000 0.0000 0 0.0000 0.0093
[24.17] 0.0000 0.5205 0.0000 605 0.0084 0.0000 2.2000 0.0000 0 0.0000 0.0084
[24.33] 0.0000 0.5205 0.0000 605 0.0068 0.0000 2.2000 0.0000 0 0.0000 0.0068
[24.50] 0.0000 0.5205 0.0000 605 0.0055 0.0000 2.2000 0.0000 0 0.0000 0.0055
[24.67] 0.0000 0.5205 0.0000 605 0.0044 0.0000 2.2000 0.0000 0 0.0000 0.0044
[24.83] 0.0000 0.5205 0.0000 605 0.0036 0.0000 2.2000 0.0000 0 0.0000 0.0036
[25.00] 0.0000 0.5205 0.0000 605 0.0029 0.0000 2.2000 0.0000 0 0.0000 0.0029
0.5205 1.0076 2.2000 0.0000
6-
APPENDIX I
Subsection 5
Post-development runoff calculations for the design storms.
PROJECT, Ramey Drainage
Generation of Postdevelopment Runoff Hydrograph - Santa Barbara Urban Hydrograph Method
25 yr storm (A) Qpeak = 0.0627 cfs
Vtotal = 1326 cu- ft
Pervious Portion of Basin Impervious Portion of Basin
Pervious Area = 11438.86 sq ft Impervious Area = 2500.344 sq ft
= 0.2626 Ac = 0.0574 Ac
Runoff Curve Number, Cn = 85.3 Runoff Curve Number, Cn = 98.0
Time of Concentrat'n, Tc = 27 min Time of Concentrat'n, Tc = 27 min
Pot'1 Max Nat'l Det'n, S = 1.7233 in Pot'1 Max Nat'l Det'n, S = 0.2041 in
Routing Coefficient, w = 0.1563 Routing Coefficient, w = 0.1563
Cumulative Cumulative
Cumulative Instan- Instan- Cumulative Instan- Instan-
Excess Excess taneous taneous Routed Excess Excess taneous taneous Routed Total
Precip Precip Runoff Runoff Runoff Precip Precip Runoff Runoff Runoff Runoff
Time R Rc Qi Vc Qr R Rc Qi Vc Qr Q
(hrs) (in) (in) (cfs) (cu ft) (cfs) (in) (in) (cfs) (Cu ft) (cfs) (cfs)
[0.00] 0.0000 0.0000 0.0000 0 0.0000 0.0000 0.0000 0.0000 0 0.0000 0.0000
[0.17) 0.0000 0.0000 0.0000 0 0.0000 0.0000 0.0000 0.0000 0 0.0000 0.0000
[0.33] 0.0000 0.0000 0.0000 0 0.0000 0.0000 0.0000 0.0000 0 0.0000 0.0000
(0.50] 0.0000 0.0000 0.0000 0 0.0000 0.0000 0.0000 0.0000 0 0.0000 0.0000
[0.67] 0.0000 0.0000 0.0000 0 0.0000 0.0000 0.0000 0.0000 0 0.0000 0.0000
[0.83] 0.0000 0.0000 0.0000 0 0.0000 0.0000 0.0000 0.0000 0 0.0000 0.0000
[1.00] 0.0000 0.0000 0.0000 0 0.0000 0.0006 0.0007 0.0002 0 0.0000 0.0000
[1.17] 0.0000 0.0000 0.0000 0 0.0000 0.0013 0.0019 0.0004 0 0.0001 0.0001
[1.33] 0.0000 0.0000 0.0000 0 0.0000 0.0018 0.0037 0.0006 1 0.0003 0.0003
[1.50] 0.0000 0.0000 0.0000 0 0.0000 0.0023 0.0061 0.0008 1 0.0004 0.0004
[1.67] 0.0000 0.0000 0.0000 0 0.0000 0.0028 0.0089 0.0010 2 0.0006 0.0006
[1.83] 0.0000 0.0000 0.0000 0 0.0000 0.0040 0.0129 0.0014 3 0.0008 0.0008
[2.00] 0.0000 0.0000 0.0000 0 0.0000 0.0046 0.0175 0.0016 4 0.0010 0.0010
[2.17] 0.0000 0.0000 0.0000 0 0.0000 0.0051 0.0226 0.0018 5 0.0012 0.0012
[2.33] 0.0000 0.0000 0.0000 0 0.0000 0.0055 0.0282 0.0019 6 0.0014 0.0014
[2.50) 0.0000 0.0000 0.0000 0 0.0000 0.0059 0.0341 0.0021 7 0.0016 0.0016
[2.67] 0.0000 0.0000 0.0000 0 0.0000 0.0063 0.0404 0.0022 8 0.0018 0.0018
[2.83] 0.0000 0.0000 0.0000 0 0.0000 0.0080 0.0483 0.0028 10 0.0020 0.0020
[3.00] 0.0000 0.0000 0.0000 0 0.0000 0.0084 0.0567 0.0029 12 0.0022 0.0022
[3.17] 0.0000 0.0000 0.0000 0 0.0000 0.0087 0.0654 0.0030 14 0.0025 0.0025
(3.33] 0.0000 0.0000 0.0000 0 0.0000 0.0090 0.0744 0.0031 16 0.0027 0.0027
[3.50] 0.0000 0.0000 0.0000 0 0.0000 0.0093 0.0838 0.0032 17 0.0028 0.0028
[3.67] 0.0000 0.0000 0.0000 0 0.0000 0.0096 0.0934 0.0033 19 0.0030 0.0030
(3.83] 0.0000 0.0000 0.0000 0 0.0000 0.0115 0.1048 0.0040 22 0.0032 0.0032
(4.00] 0.0000 0.0000 0.0000 0 0.0000 0.0118 0.1166 0.0041 24 0.0034 0.0034
[4.17] 0.0000 0.0000 0.0000 0 0.0000 0.0120 0.1286 0.0042 27 0.0037 0.0037
(4.33] 0.0000 0.0000 0.0000 0 0.0000 0.0122 0.1408 0.0042 29 0.0038 0.0038
[4.50) 0.0000 0.0000 0.0000 0 0.0000 0.0124 0.1533 0.0043 32 0.0040 0.0040
(4.67] 0.0000 0.0000 0.0000 0 0.0000 0.0126 0.1659 0.0044 35 0.0041 0.0041
(4.83] 0.0000 0.0000 0.0000 0 0.0000 0.0150 0.1809 0.0052 38 0.0043 0.0043
[5.00] 0.0002 0.0002 0.0003 0 0.0000 0.0152 0.1961 0.0053 41 0.0046 0.0046
[5.17] 0.0005 0.0007 0.0008 1 0.0002 0.0154 0.2115 0.0053 44 0.0048 0.0050
[5.33] 0.0009 0.0016 0.0014 2 0.0005 0.0156 0.2271 0.0054 47 0.0050 0.0055
[5.50] 0.0012 0.0028 0.0020 3 0.0009 0.0157 0.2428 0.0055 51 0.0051 0.0060
[5.67] 0.0016 0.0044 0.0025 4 0.0013 0.0159 0.2587 0.0055 54 0.0052 0.0065
[5.83] 0.0022 0.0066 0.0035 6 0.0018 0.0185 0.2772 0.0064 58 0.0055 0.0073
[6.00] 0.0026 0.0093 0.0042 9 0.0025 0.0187 0.2959 0.0065 62 0.0058 0.0082
[6.17] 0.0030 0.0123 0.0048 12 0.0031 0.0188 0.3148 0.0065 66 0.0060 0.0091
(6.33] 0.0034 0.0157 0.0055 15 0.0037 0.0190 0.3337 0.0066 70 0.0062 0.0099
[6.50] 0.0038 0.0196 0.0061 19 0.0044 0.0191 0.3528 0.0066 74 0.0063 0.0107
(6.67] 0.0042 0.0238 0.0067 23 0.0050 0.0192 0.3720 0.0067 78 0.0064 0.0114
(6.83] 0.0065 0.0302 0.0103 29 0.0061 0.0270 0.3990 0.0094 83 0.0069 0.0130
[7.00] 0.0071 0.0374 0.0113 36 0.0076 0.0272 0.4262 0.0094 89 0.0077 0.0153
[7.17] 0.0078 0.0451 0.0123 43 0.0089 0.0273 0.4535 0.0095 94 0.0083 0.0171
[7.33] 0.0115 0.0566 0.0183 54 0.0109 0.0372 0.4907 0.0129 102 0.0092 0.0201
(7.50] 0.0125 0.0692 0.0199 66 0.0135 0.0374 0.5281 0.0130 110 0.0104 0.0238
[7.67] 0.0264 0.0955 0.0419 91 0.0189 0.0712 0.5993 0.0247 125 0.0130 0.0319
[7.83] 0.0484 0.1439 0.0769 137 0.0316 0.1141 0.7134 0.0396 149 0.0190 0.0506
[8.00] 0.0268 0.1708 0.0427 163 0.0404 0.0574 0.7708 0.0199 161 0.0224 0.0627
[8.17] 0.0188 0.1896 0.0299 181 0.0391 0.0384 0.8092 0.0133 169 0.0206 0.0597
[8.33] 0.0144 0.2040 0.0229 194 0.0351 0.0286 0.8378 0.0099 175 0.0178 0.0529
[8.50] 0.0148 0.2188 0.0235 209 0.0314 0.0287 0.8664 0.0100 181 0.0153 0.0467
[8.67] 0.0151 0.2339 0.0241 223 0.0290 0.0287 0.8951 0.0100 187 0.0137 0.0427
(8.83] 0.0101 0.2441 0.0161 233 0.0262 0.0189 0.9140 0.0066 190 0.0120 0.0382
[9.00] 0.0103 0.2543 0.0163 242 0.0231 0.0189 0.9329 0.0066 194 0.0103 0.0334
[9.17] 0.0104 0.2647 0.0165 252 0.0210 0.0189 0.9518 0.0066 198 0.0091 0.0301
(9.33] 0.0105 0.2753 0.0168 262 0.0196 0.0189 0.9707 0.0066 202 0.0083 0.0280
PROJECT: Ramey Drainage
•
Generation of Postdevelopment Runoff Hydrograph - Santa Barbara Urban Hydrograph Method
25 yr storm (A) Qpeak = 0.0627 cfs
Vtotal = 1326 cu ft
Pervious Portion of Basin Impervious Portion of Basin
Pervious Area = 11438.86 sq ft Impervious Area = 2500.344 sq ft
= 0.2626 Ac 0.0574 Ac
Runoff Curve Number, Cn = 85.3 Runoff Curve Number, Cn = 98.0
Time of Concentrat'n, Tc = 27 min Time of Concentrat'n, Tc = 27 min
Pot'1 Max Nat'l Det'n, S = 1.7233 in Pot'1 Max Nat'l Det'n, S = 0.2041 in
Routing Coefficient, w = 0.1563 Routing Coefficient, w - 0.1563
Cumulative Cumulative
Cumulative Instan- Instan- Cumulative Instan- Instan-
Excess Excess taneous taneous Routed Excess Excess taneous taneous Routed Total
Precip Precip Runoff Runoff Runoff Precip Precip Runoff Runoff Runoff Runoff
Time R Rc Qi Vc Qr R Rc Qi Vc Qr Q
(hrs) (in) (in) (cfs) (cu ft) (cfs) (in) (in) (cfs) (cu ft) (cfs) (cfs)
[9.50] 0.0107 0.2860 0.0170 273 0.0188 0.0189 0.9896 0.0066 206 0.0078 0.0265
[9.67] 0.0108 0.2968 0.0172 283 0.0182 0.0189 1.0086 0.0066 210 0.0074 0.0256
[9.83] 0.0109 0.3077 0.0174 293 0.0179 0.0189 1.0275 0.0066 214 0.0071 0.0251
[10.00] 0.0111 0.3188 0.0176 304 0.0178 0.0190 1.0465 0.0066 218 0.0070 0.0248
[10.17] 0.0112 0.3299 0.0178 314 0.0177 0.0190 1.0654 0.0066 222 0.0068 0.0246
[10.33] 0.0113 0.3412 0.0179 325 0.0178 0.0190 1.0844 0.0066 226 0.0068 0.0245
(10.50) 0.0114 0.3526 0.0181 336 0.0179 0.0190 1.1034 0.0066 230 0.0067 0.0246
[10.67] 0.0115 0.3642 0.0183 347 0.0180 0.0190 1.1224 0.0066 234 0.0067 0.0246
[10.83] 0.0095 0.3737 0.0151 356 0.0176 0.0156 1.1379 0.0054 237 0.0065 0.0240
[11.00] 0.0096 0.3832 0.0152 365 0.0168 0.0156 1.1535 0.0054 240 0.0061 0.0230
[11.17) 0.0097 0.3929 0.0153 375 0.0163 0.0156 1.1691 0.0054 244 0.0059 0.0222
[11.33] 0.0097 0.4026 0.0155 384 0.0160 0.0156 1.1846 0.0054 247 0.0057 0.0218
[11.50] 0.0098 0.4124 0.0156 393 0.0159 0.0156 1.2002 0.0054 250 0.0056 0.0215
[11.67] 0.0099 0.4223 0.0157 403 0.0158 0.0156 1.2158 0.0054 253 0.0056 0.0214
[11.83] 0.0099 0.4322 0.0158 412 0.0158 0.0156 1.2314 0.0054 257 0.0055 0.0213
[12.00] 0.0100 0.4422 0.0159 422 0.0158 0.0156 1.2470 0.0054 260 0.0055 0.0213
[12.17] 0.0101 0.4523 0.0160 431 0.0158 0.0156 1.2626 0.0054 263 0.0055 0.0213
[12.33] 0.0101 0.4624 0.0161 441 0.0159 0.0156 1.2782 0.0054 266 0.0054 0.0213
[12.50] 0.0102 0.4726 0.0162 450 0.0160 0.0156 1.2938 0.0054 270 0.0054 0.0214
[12.67] 0.0102 0.4828 0.0163 460 0.0161 0.0156 1.3094 0.0054 273 0.0054 0.0215
[12.83] 0.0082 0.4910 0.0130 468 0.0156 0.0124 1.3217 0.0043 275 0.0053 0.0209
[13.00] 0.0082 0.4992 0.0130 476 0.0148 0.0124 1.3341 0.0043 278 0.0050 0.0197
[13.17) 0.0082 0.5074 0.0131 484 0.0142 0.0124 1.3464 0.0043 281 0.0047 0.0190
[13.33] 0.0083 0.5157 0.0131 492 0.0139 0.0124 1.3588 0.0043 283 0.0046 0.0185
[13.50] 0.0083 0.5240 0.0132 499 0.0137 0.0124 1.3712 0.0043 286 0.0045 0.0182
[13.67] 0.0083 0.5323 0.0132 507 0.0135 0.0124 1.3836 0.0043 288 0.0044 0.0180
[13.83] 0.0084 0.5407 0.0133 515 0.0134 0.0124 1.3959 0.0043 291 0.0044 0.0178
[14.00] 0.0084 0.5491 0.0134 523 0.0134 0.0124 1.4083 0.0043 293 0.0044 0.0178
[14.17] 0.0084 0.5575 0.0134 531 0.0134 0.0124 1.4207 0.0043 296 0.0043 0.0177
[14.33] 0.0085 0.5660 0.0135 540 0.0134 0.0124 1.4331 0.0043 299 0.0043 0.0177
[14.50] 0.0085 0.5745 0.0135 548 0.0134 0.0124 1.4455 0.0043 301 0.0043 0.0178
[14.67] 0.0085 0.5831 0.0136 556 0.0135 0.0124 1.4578 0.0043 304 0.0043 0.0178
[14.83] 0.0075 0.5906 0.0119 563 0.0133 0.0109 1.4687 0.0038 306 0.0042 0.0175
[15.00] 0.0075 0.5981 0.0120 570 0.0128 0.0109 1.4796 0.0038 308 0.0041 0.0169
(15.17] 0.0076 0.6057 0.0120 577 0.0126 0.0109 1.4904 0.0038 311 0.0040 0.0166
[15.33] 0.0076 0.6133 0.0121 585 0.0124 0.0109 1.5013 0.0038 313 0.0039 0.0163
[15.50] 0.0076 0.6209 0.0121 592 0.0123 0.0109 1.5122 0.0038 315 0.0039 0.0162
[15.67] 0.0076 0.6286 0.0121 599 0.0123 0.0109 1.5231 0.0038 317 0.0038 0.0161
[15.83] 0.0077 0.6362 0.0122 606 0.0122 0.0109 1.5339 0.0038 320 0.0038 0.0160
[16.00] 0.0077 0.6439 0.0122 614 0.0122 0.0109 1.5448 0.0038 322 0.0038 0.0160
[16.17] 0.0077 0.6516 0.0123 621 0.0122 0.0109 1.5557 0.0038 324 0.0038 0.0160
[16.33] 0.0077 0.6594 0.0123 629 0.0122 0.0109 1.5666 0.0038 326 0.0038 0.0160
[16.50] 0.0078 0.6671 0.0123 636 0.0123 0.0109 1.5774 0.0038 329 0.0038 0.0160
[16.67] 0.0078 0.6749 0.0124 643 0.0123 0.0109 1.5883 0.0038 331 0.0038 0.0161
[16.83] 0.0067 0.6816 0.0107 650 0.0120 0.0094 1.5977 0.0033 333 0.0037 0.0157
[17.00] 0.0063 0.6879 0.0099 656 0.0115 0.0087 1.6064 0.0030 335 0.0035 0.0150
[17.17] 0.0063 0.6941 0.0100 662 0.0110 0.0087 1.6151 0.0030 337 0.0034 0.0144
[17.33] 0.0063 0.7004 0.0100 668 0.0107 0.0087 1.6238 0.0030 338 0.0033 0.0139
[17.50] 0.0063 0.7067 0.0100 674 0.0105 0.0087 1.6325 0.0030 340 0.0032 0.0137
[17.67] 0.0063 0.7130 0.0100 680 0.0103 0.0087 1.6412 0.0030 342 0.0031 0.0135
[17.83] 0.0063 0.7193 0.0100 686 0.0102 0.0087 1.6499 0.0030 344 0.0031 0.0133
[18.00] 0.0063 0.7257 0.0101 692 0.0102 0.0087 1.6587 0.0030 346 0.0031 0.0133
[18.17] 0.0064 0.7320 0.0101 698 0.0101 0.0087 1.6674 0.0030 347 0.0031 0.0132
[18.33) 0.0064 0.7384 0.0101 704 0.0101 0.0087 1.6761 0.0030 349 0.0031 0.0132
[18.50] 0.0064 0.7448 0.0101 710 0.0101 0.0087 1.6848 0.0030 351 0.0030 0.0132
[18.67] 0.0064 0.7512 0.0102 716 0.0101 0.0087 1.6935 0.0030 353 0.0030 0.0132
[18.83) 0.0064 0.7576 0.0102 722 0.0101 0.0087 1.7022 0.0030 355 0.0030 0.0132
PROJECT: Ramey Drainage
Generation of Postdevelopment Runoff Hydrograph - Santa Barbara Urban Hydrograph Method
25 yr storm (A) Qpeak = 0.0627 cfs
Vtotal = 1326 cu ft
Pervious Portion of Basin Impervious Portion of Basin
Pervious Area = 11438.86 sq ft Impervious Area = 2500.344 sq ft
= 0.2626 Ac 0.0574 Ac
Runoff Curve Number, Cn = 85.3 Runoff Curve Number, Cn = 98.0
Time of Concentrat'n, Tc = 27 min Time of Concentrat'n, Tc = 27 min
Pot'l Max Nat'l Det'n, S = 1.7233 in Pot'l Max Nat'l Det'n, S = 0.2041 in
Routing Coefficient, w = 0.1563 Routing Coefficient, w = 0.1563
Cumulative Cumulative
Cumulative Instan- Instan- Cumulative Instan- Instan-
Excess Excess taneous taneous Routed Excess Excess taneous taneous Routed Total
Precip Precip Runoff Runoff Runoff Precip Precip Runoff Runoff Runoff Runoff
Time R Rc Qi Vc Qr R Rc Qi Vc Qr Q
(hrs) (in) (in) (cfs) (cu ft) (cfs) (in) (in) (cfs) (cu ft) (cfs) (cfs)
[19.00] 0.0064 0.7640 0.0102 728 0.0102 0.0087 1.7109 0.0030 356 0.0030 0.0132
[19.17] 0.0064 0.7704 0.0102 734 0.0102 0.0087 1.7197 0.0030 358 0.0030 0.0132
[19.33] 0.0064 0.7769 0.0102 741 0.0102 0.0087 1.7284 0.0030 360 0.0030 0.0132
[19.50] 0.0065 0.7833 0.0103 747 0.0102 0.0087 1.7371 0.0030 362 0.0030 0.0132
[19.67] 0.0065 0.7898 0.0103 753 0.0102 0.0087 1.7458 0.0030 364 0.0030 0.0132
[19.83] 0.0065 0.7962 0.0103 759 0.0102 0.0087 1.7545 0.0030 366 0.0030 0.0133
[20.00] 0.0065 0.8027 0.0103 765 0.0103 0.0087 1.7633 0.0030 367 0.0030 0.0133
[20.17] 0.0065 0.8092 0.0103 771 0.0103 0.0087 1.7720 0.0030 369 0.0030 0.0133
[20.33] 0.0065 0.8157 0.0103 778 0.0103 0.0087 1.7807 0.0030 371 0.0030 0.0133
[20.50] 0.0065 0.8223 0.0104 784 0.0103 0.0087 1.7894 0.0030 373 0.0030 0.0133
[20.67] 0.0065 0.8288 0.0104 790 0.0103 0.0087 1.7981 0.0030 375 0.0030 0.0134
[20.83] 0.0065 0.8354 0.0104 796 0.0104 0.0087 1.8069 0.0030 376 0.0030 0.0134
[21.00] 0.0066 0.8419 0.0104 803 0.0104 0.0087 1.8156 0.0030 378 0.0030 0.0134
[21.17] 0.0066 0.8485 0.0104 809 0.0104 0.0087 1.8243 0.0030 380 0.0030 0.0134
[21.33] 0.0066 0.8551 0.0105 815 0.0104 0.0087 1.8330 0.0030 382 0.0030 0.0134
[21.50] 0.0066 0.8617 0.0105 821 0.0104 0.0087 1.8418 0.0030 384 0.0030 0.0135
[21.67] 0.0066 0.8683 0.0105 828 0.0104 0.0087 1.8505 0.0030 386 0.0030 0.0135
[21.83] 0.0066 0.8749 0.0105 834 0.0105 0.0087 1.8592 0.0030 387 0.0030 0.0135
[22.00] 0.0066 0.8815 0.0105 840 0.0105 0.0087 1.8679 0.0030 389 0.0030 0.0135
[22.17] 0.0066 0.8882 0.0105 847 0.0105 0.0087 1.8767 0.0030 391 0.0030 0.0135
[22.33] 0.0066 0.8948 0.0106 853 0.0105 0.0087 1.8854 0.0030 393 0.0030 0.0135
[22.50] 0.0067 0.9015 0.0106 859 0.0105 0.0087 1.8941 0.0030 395 0.0030 0.0136
[22.67] 0.0067 0.9081 0.0106 866 0.0106 0.0087 1.9029 0.0030 396 0.0030 0.0136
[22.83] 0.0067 0.9148 0.0106 872 0.0106 0.0087 1.9116 0.0030 398 0.0030 0.0136
[23.00] 0.0067 0.9215 0.0106 878 0.0106 0.0087 1.9203 0.0030 400 0.0030 0.0136
[23.17] 0.0067 0.9282 0.0106 885 0.0106 0.0087 1.9291 0.0030 402 0.0030 0.0136
[23.33] 0.0067 0.9349 0.0107 891 0.0106 0.0087 1.9378 0.0030 404 0.0030 0.0137
[23.50] 0.0067 0.9417 0.0107 898 0.0106 0.0087 1.9465 0.0030 406 0.0030 0.0137
[23.67] 0.0067 0.9484 0.0107 904 0.0107 0.0087 1.9553 0.0030 407 0.0030 0.0137
[23.83] 0.0067 0.9551 0.0107 910 0.0107 0.0087 1.9640 0.0030 409 0.0030 0.0137
[24.00] 0.0068 0.9619 0.0107 917 0.0107 0.0087 1.9727 0.0030 411 0.0030 0.0137
[24.17] 0.0000 0.9619 0.0000 917 0.0090 0.0000 1.9727 0.0000 411 0.0026 0.0116
[24.33] 0.0000 0.9619 0.0000 917 0.0062 0.0000 1.9727 0.0000 411 0.0018 0.0080
[24.50] 0.0000 0.9619 0.0000 917 0.0043 0.0000 1.9727 0.0000 411 0.0012 0.0055
[24.67] 0.0000 0.9619 0.0000 917 0.0029 0.0000 1.9727 0.0000 411 0.0008 0.0038
[24.83] 0.0000 0.9619 0.0000 917 0.0020 0.0000 1.9727 0.0000 411 0.0006 0.0026
[25.00] 0.0000 0.9619 0.0000 917 0.0014 0.0000 1.9727 0.0000 411 0.0004 0.0018
0.9619 1.5282 max = 0.0404 1.9727 0.6851 max = 0.0224 0.0627
1
t
Appendix II
Conveyance System Specifications and Detail Drawings
Drainage, Erosion, and Sediment Control Plan
for
Parcel Number 937800116
Detention System Specifications and Detail Drawings
General Notes
Construct a shallow interception ditch across the southwestern edge of the parcel,
beginning 20 feet northwest of the roadside ditch at Victoria Loop and connecting to
the interception ditch (described immediately below) across the top of the bluff. The
ditch shall be a minimum of 6 inches deep and may be gently sloped and grassed
(mowable) or rock lined.
Construct a second shallow interception ditch across the northwestern edge of the
building site, parallel to and a minimum of 30 feet back from the bluff. This ditch
shall also be a minimum of 6 inches deep and gently sloped and grassed (mowable)
or rock lined.
Roof drains shall be tightlined to one or both of the interception ditches. Discharge
points where roof drains enter the ditches shall be armored with quarry spalls or
splash blocks or other suitable devices for protection from erosion.
Great care shall be taken that the collection system (roof drains and interception
ditches) cannot allow concentrated discharges to flow over the bluff.
/
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;
,.,-
...7
. :
) .
, .
/{:,.if,,
. .
I: 1..V,
.!;
.. <
• : ,
. s.,
. ...
„7,-..------------------i .-71 •
. -t---
.- •
3" SCH 40 PVC PIPE .
• :
lkl..e----TO TOP OF BLUFF • I
INLET .....1_ \ ..e.c.,...../— -N i ;-4 0 - I. c•\
‘4'''.../A
PI 1 1 71'
/
-. j /
•
.";
zni
I .
I r ,.
CONSTRUCT INTERCEPTION DITCHES
• I:
ACROSS SOUTHWESTERN AND
NORTHWESTERN SIDES OF PROPERTY •
:AS SHOWN
:.
. ... .,
,....;.)
i#".' i T___H ____ __ ,11.. J_____, , ,.,,,...j.),*) ari• ,,..„_. ;/
_ - i ... • ., _
: --. - --
. . _.
• .
1.1.
1 ,,...
i i ..".. ,
t I ;
1(7. ' -'
1 4-1 V`• ; - . i . ..
! 1
\.....`,
S, ..---, .---,t-- ...I
i '.1
1
_
Z.
.... ;
1 6: , r.,----.,
. . .-____,•
S.
: -,..,
1 • i 'i(.:t
i
--4 :
‘1.\• ...
i. .
L_L)-c;t":'
. . .
, .
INTERCEPTOR DITCH
BOTTOM OF
DITCH
- _ . SLOPE DITCH BOTTOM
TO MATCH RIM OF
CATCH BASIN
GARDEN" TYPE CATCH
3' SCH 40 PVC PIPE BASIN WITH MINIMUM
GRATE SIZE OF 12 x 12
PIPE INLET DETAIL
NO SCALE
NORTHWESTERN TERRITORIES, INC.
,$_ Engineers — Land Surveyors — Geologists
1 Construction Inspection — Materials Testing
Nil 717 SOUTH PEABODY,PORT ANGELES,WASHINGTON 98362,(360)452-8491
SIMILAR AUGER
TYPE SOIL ANCHOR, SET BACK
A MINIMUM OF 10 FEET FROM
EDGE OF BLUFF.
1/2 IN DH GAL
VANIZED WIREMOBILE HOME OR
•
ROPE OR CABLE; THREADED
THROUGH PIPE AS SHOWN
AND ATTACHED TO ANCHORS 2' (MIN)
WITH 2 OR MORE WIRE CUPS
OR A SPLICED OR PRESSED
EYE. )� � __
TEE OR WYE FITTING II
1 \ \
/I HOT BEND PIPE OR USE
f LONG SWEEPS 70 MACH
SLOPE OF GROUND
3 INCH DIA, SCH 40 PVC
PIPE WITH SOLVENT WELD
(GLUED) FITTINGS. HDPE
PIPE WAH WELDED JOIN15
AND FITTINGS MAY BE USED `'%
CORRUGATED THIN WALL //
PE PIPE IS NOT SUITABLE. BREAKS AND IRREGULARRjES IN
THE FACE OF THE BLUFF ARE
I
NOT SHOWN. PIPE JONV13 LONG
SWEEP$ OR HOT BENDS MAY
I
BE USED TO M ICH THE PIPE TO
THE FACE OF THE DUFF. PROWDE
ADOFF MORE
ANCHOR(S) ATBENDS
MOBILE HOME OR SIMILAR AUGER
I/IR
TYPE SOIL ANCHOR, SET IN FACE CAP ON 130770M OF PIPE M REST
OF BLUFF THREE FEET ABOVE AGAINST EYE OF ANCHOR DRILL HOLE
LEVEL OF BEACH / IN CAP FOR CABLE CAP MMY BE SLOTTED
TO ALLOW INSTALLATION AFTER PLACEMENT
OF CABLE. DRILL 25 EACH I INCH
DIAMETER HOLES EVENLY SPACED IN
11• LOWER THREE FEET OF PIPE TO PROVIDE
• ENERGY DISSIPATION.
PLACE 12 NCH DIAME7ER STONES UNDER
��--� FOR (ADDITIONAL ENERGY DISSIPATION.
STONES TO EXTEND A MINIMUM OF 2 FEET
IN ALL DIRECTIONS.
,I07 NORTHWESTERN TERRITORIES, INC.
1111 4 .77_
N Engineers — Land Surveyors — Geologists
Construction Inspection — Materials Testing
N/T!I 717 SOUTH PEABODY,PORT ANGELES,WASHINGTON 98362,(360)452-8491