HomeMy WebLinkAboutCT 08-02; LA COSTA CANYON HOMES; STORMWATER MANAGEMENT PLAN; 2008-11-10I
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Prepared by:
STORMWATER MANAGEMENT PLAN
LA COSTA CANYON HOMES
LOTS 408-409
La Costa, Carlsbad
SAN DIEGO COUNTY, CALIFORNIA
CTOS"'02
Owner:
LEGACY DEVELOPMENT, LLC.
STEVE GRADY
7938 Ivanhoe Ave., Suite B
La Jolla, CA 92037
(619) 491-9200
Engineer:
MASSON & ASSOCIATES, INC.
200 East Washington Avenue, Suite 200,
Escondido, CA 92025
(760) 741-3570
Mr9VU~ ~J?o~
Monika Kosowska
Under supervision of:
Scott L. Lee
RCE 70889
Date Prepared:
Date Revised:
P.N.0040
November 20,2007
September 17, 2008
November 10,2008 RECEIVED
'. '1"" MAY),·l2CG9'
CITY OF CARLSBAD
PLANNING DEPT
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TABLE OF CONTENTS
VICINITY MAP ................................................................................................................. ii
INTRODUCTION ............................................................................................................. 1
1. PROJECT DESCRIPTION ............................................................................ · ............. 1
.1.1 Topography and Land Use ................................................................................. 1
1.2 Hydrologic Unit Contribution ................................................................................ 1
2. WATER QUALITY ENVIRONMENT ........................................................................... 1
2.1 Beneficial Uses ........................................................................................ : .......... 1
2.1.1 Inland Surface Waters ................................................................. : ........... 2
2.1.2 Groundwater ............................................................................................ 3
2.2 303(d) Status ...................................................................................................... 3
3. CHARACTERIZATION OF PROJECT RUNOFF ........................................................ 3
3.1 Existing and Post-Construction Drainage ........................................................... 3
3.2 Post-Construction Expected Discharges ........................................................... .4
3.3 Soil Characteristics .............................................................................................. 4 .
4. MITIGATION MEASURES TO PROTECT WATER QUALITY ................................... 5
4.1 Construction BMPs ............................................................................................. 5
4.2 Post-construction BMPs ..................................................................................... 5
4.2.1 Site Design BMPs .................................................................................... 5
4.2.2 Source Control BMPs .............................................................................. 6
4.2.3 BMPs Applicable to Individual Priority Project Categories ....................... 6
4.2.4 Low Impact Development (L.I.D.) ............................................................ 7
4.2.5 Treatment Control BMPs ........................................... ~ ... , ......................... 7
5. TREATMENT CONTROL BMP SELECTION DISSCUSSION ................................... 9
6. OPERATION AND MAINTENANCE PROGRAM ..................................................... 12
7. FISCAL RESOURCES .............................................................................................. 12
8. SUMMARY AND CONCLUSIONS .......................................................................... 12
APPENDIX A .
Storm Water Requirements Applicability Checklist
APPENDIX B
Table A -Anticipated and Potential Pollutants Generated by Land Use Type.
Table B -Storm Water BMP Requirements Matrix .
Attachment TC-30 -Vegetated Swale
Rainfall Isopluvial Maps
APPENDIXC
Bio-swale Calculations
Exhibit A -Water Quality Exhibit
APPENDIXD
Pre-development Hydrology Calculations
Exhibit 'B' Pre-development Hydrology Map
APPENDIX E
Post-development Hydrology Calculations
Exhibit 'c' Post-development Hydrology Map
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INTRODUCTION
The Stormwater Management Plan (SWMP) is required by the City' of Carlsbad.
The purpose of this SWMP is to address the water quality impacts from the proposed
improvements on the La Costa project in Carlsbad, CA. Best Management Practices'
(BMPs) will be utilized to provide a long-term solution to water quality. This SWMP is also
intended to ensure the effectiveness of the BMPs through proper maintenance that is '
based on long-term fiscal planning. The SWMP is subject to revisions as needed bY the .
engineer.
1.0 PROJECT DESCRIPTION
The proposed project is located on La Costa Avenue, Carlsbad, California. The'
project consists of 8 condominium units and underground parking, lot. The site . is .
accessible from La Costa Avenue. The entire site is approximately 0.9 Ac.
Most of the site (basin 2.01, 2.03) drains currently towards the curb and gutter in
La Costa Avenue. North portion of the property (basin 1.01) drains northerly to an
existing brow ditch, located on the existing slope that drains on the easterly direction
into the natural open space.
1.1 Topography and Land Use
The property is currently rough graded with existing slope draining north towards
existing brow ditch. Currently there are no existing strl:lctures on the property.' The
majority of the site drains southerly towards La Costa Avenue to the existing curb and
gutter. .
1.2 Hydrologic Unit Contribution
The project is within the Batiquitos Hydrblogic Subarea (4.51) of the Carlsb'ad
Hydrologic Unit (4.00) as described by the Water Quality Control Plan for the San Diego
Basin ("Basin Plan"), adopted by the California Regional Water Quality Control Board,
San Diego Region, dated September 8, 1994 and amended May 5, 1998. The receiving
water of this project site is San Marcos Creek.
2.0 WATER QUALITY ENVIRONMENT
2.1 Beneficial Uses
The beneficial uses for the hydrologic unit are included in Tables 2.1 and 2.2.
These tables have been extracted from the Water Quality Control Plan for the San
Diego Basin.
Municipal and Domestic Supply (MUN) -Includes uses of water for community, military,
or individual water supply systems including, but not limited to, drinking water supply.'
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Agricultural Supply (AGR) -Includes uses of water for farming, horticulture, or ranching
including, but not limited to, irrigation, stock watering, or support of vegetation for range
grazing.
Contact Water Recreation (REC-1) -Includes uses of water for recreational activities
involving body contact with water, where ingestion of water is reasonably possible. These
uses include, but are not limited to, swimming, wading, water-skiing, skin and SCUBA
diving, surfing, white water activities, fishing, or use of natural hot springs.
Non-contact Water Recreation (REC-2) -Includes the uses of water for recreational
activities involving proximity to water, but not normally involving body contact with water,
where ingestion of water is reasonably possible .. These uses include, but are not limited
to, picnicking, sunbathing, hiking, beachcombing, camping, boating, tidepool and marine
life study, hunting, sightseeing, or aesthetic enjoyment in conjunction with the above
activities.
Warm Freshwater Habitat (WARM) -Includes uses of water that support Warm water-
ecosystems including, but not limited to, preservation or enhancement of aquatic habitats,
vegetation, fish or wildlife, including invertebrates.
Wildlife Habitat (WilD) -Includes uses of water that support terrestrial ecosystems
including, but not limited to, preservation and enhancement of terrestrial habitats,
vegetation, wildlife (e.g., mammals, birds, reptiles, amphibians, invertebrates), or wildlif~
water and food sources.
Preservation of Biological Habitats of Special Significance (BIOl) -Designated areas or
habitats such as established refuges, parks, sanctuaries, ecological reserves, or Areas of
Special Biological Significance (ASBS), where the preservation or enhancement of
natural resources requires special protection.
Estuarine Habitat (EST) -Esturarine ecosystems inciuding,l;>ut not limited 'to,
preservation or enhancement of esturarine habitats, vegetation, fish, shellfish, or wildlife
(e.g. esturarine mammals, shorebirds).
Cold Freshwater Habitat (COLD) -Cold water ecosystem including, but not limited' to,
preservation or enhancement of aquatic habitats, vegetation, fish or wildlife, incl.uding
invertebrates.
Industrial Service Supply (lND) -Industrial activities that do not depend primarily on water
quality including, but not limited to mining, cooling water supply, hydraulic conveyance,
gravel washing, fire protection, or oil well re-pressurization.
2.1.1 Inland Surface Waters I . Inland surface waters have the following beneficial·uses as shown in Table 2.1.
Table 2.1 Beneficial Uses for Inland Surface Waters
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Hydrologic
Unit Number
.,.-N E :!2 -0 c: .... C,.) C,.) .... (5 ttl ..... (5 :::l ~ CD CD ~ CI) -0 :2: 0:: 0:: S as UJ () c:
904.51 x x x x x x x x x x
2.1.2· Ground Waters
Ground waters have the following beneficial uses as shown in Table 2.2.
Table 2.2 Beneficial Uses for Ground Waters
Hydrologic
Unit Number
c: .... :::l 0> -0
:2: « oS
904.51 x x x
2.2 303(d) Status
According to. the Califarnia 2006 303d list published by the San Diego Regional
Water Quality Control Board, the nearest impaired water body is the Pacific Ocean
outfall from .
San Marcos, Hydrolagic Area 904.51.
3.0 . CHARACTERIZATION OF PROJECT RUNOFF
3.1 Existing and Post-Construction Drainage
In the existing candition the property is rough graded. Most af the site (basins
2.01, 2.03, total af 0.69 ac) currently drains .towards the curb and gutter in La C()sta .
Avenue. North partian af the property (basin 1.01, 0.18 ac) .drains northerly to an·'.
existing braw ditch, lacated at the battam of the existing slope, that drains in the easterly
direction and cantinues on the neighboring property. Small partian of the property (basin
,1.02, 0.07 ac), lacated narth af the existing brow ditch, drains in the northerly ·direction
into. the natural apen space. '.
In the past-canstruction condition reduced undisturbed slope area .in the north
part of the site (basin 1.01, 0.15ac) will continue draining towards the existing brow·
ditch. Basin 1.02 located north from the existing brow ditch will keep draining in the
northerly direction, unchanged from the pre-development condition. The rest of theon-.
site runoff will be collected using the storm drain inlets, storm drain system and bio-
swale and will be discharged into an existing curb and gutter in La Costa Avenue.
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For more detailed hydrologic calculations see Appendix 1 at the end 'of this
report. For Pre-development Hydrology Map see Exhibit 'B'; for post-development
Hydrology Map see Exhibit 'C'. Both exhibits are located at the end of this report.
A summary of the post-construction water quality flows is included in Table 3.1, , "
Table 3.1 Post-Construction Water Quality Flows
Outfall Tributary Area Q100 QWQ
(acres) (cfs) (cfs)
1.01 0.15 0.30 0.011
1.02 0.07 0.18 0.005
2.01 0.04 0.20 0.006
2.02 0.03 0.15 0.004
2.03 0.03 0.15 0.004
2.04 0.03 0.15 0.004
2.05 0.05 0.25 0.007
2.06 0.05 0.25 0.007
2.07 0.08 0.41 0.011
2.08 0.08 0.40 0.011
2.09 0.08 0.39 0.011
2.10 0.03 0.15 0.004
2.11 0.26 0.32 0.036
Table 3.2 Pre-construction Flows
Outfall Tributary Area Q100
(acresl (cfs)
1.01 0.18 0.36
1.02 0.07 0.17
2.01 0.24 0.56
2.03 0.44 0.90
3.2 Pollutants of Concern.
The following pollutants are anticipated on the projects of this type (Detached
Residential Development): '
Primary pollutants:
• Bacteria indicators;
Secondary pollutants:
• Sediments;
• Nutrients;
• Oil and grease from paved areas -from the roads;
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• Trash and debris deposited in gutters;
• Pesticides from landscaping and home use;
• Oxygen demanding substances;
See Table A: Anticipated and Potential Pollutants Generated by land Use Type.
3.3' Soil Characteristics
The project area consists of soil group C (See S.D. CQunty Hydrologic Soil
Classifications APP. IX-C2). All slopes will include slope protection for construction and
post-construction conditions. During construction Erosion' Control Mats will be used on
slopes. Post-construction landscaping will be done to protect slopes.
4.0, MITIGATION MEASURES TO PROTECT WATER QUALITY
To address water quality for the project, BMPs will be implemented during
construction and post-construction. Placements of the BMPs are as noted on Exhibit, '
'A'.
4.1 Construction BMPs
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A detailed description of the construction BMPs will be shown on the Grading
Plans and Improvement Plans. Typical BMPs include the following:" ,
• Silt Fence
• Fiber Rolls
• Sandbag Barrier
• Material Delivery and Storage
• Stockpile Management
• Solid Waste Management
• Stabilized Construction Entrance/Exit
, • Vehicle and Equipment Maintenance
• Desilting Basin
• Gravel Bag Berm
• Spill Prevention and Control
• Water Conservation Practices
• Erosion Control Mats and Spray-on Applications
4.2 Post-Construction BMPs
Pollutants of concern as noted in Section 3 will be addressed through three types
of BMPs. These types of BMPs are site design, source control and treatment control.
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4.2.1 Site Design BMPs
The project is designed to minimize the introduction of pollutants, their impact·
generated from site run-off to the storm water conveyance system and the pqtential for
. erosion.
Maintain Pre-Development Rainfall Runoff Characteristics.
1) Minimize impervious footprint.
private streets and driveways will be constructed to minimum required widths;
minimize the use of impervious. surfaces, such as decorative concrete in the
landscape areas; .
locations of buildings minimize the driveways lengths;
2) Conserve natural areas.
-development is concentrated along La Costa Avenue, there. are' no
environmentally sensitive areas on site;
-overall existing drainage patterns throughout the project and natural drainage
basins will be maintained;
3) Minimize directly connected impervious areas.
all rooftops will drain to landscaping prior to leave lot area;
impervious sidewalks, patios, hardscape runoffs will discharge to limdscape prior
to discharging onto City streets;
4) M~ximize canopy interception and water conservation .
. -the project site is currently rough graded and there are no existing' trees or
shrubs on the property;
project landscaping will incorporate native or drought tolerant vegetation whe're
practicable;
Protect Slopes and Channels.
5) Pad grading will divert runoff away from tops of slopes.
6) Slopes will be permanently stabilized with landscaping that will incorporate .native.or
drought tolerant vegetation; -
7) There are no permanent channel crossings on ~he site; '.
8) Rip rap -energy dissipaters will be installed in grass swales where flow velocities
exceed 5.0 ftls to minimize erosion;
4.2.2 Source Control BMPs . .
Design Outdoor Material Storage Areas to Reduce Pollution Introduction. . _
9) City will provide covered trash bins that will be kept in the covered trash enclosure;
Design Trash Storage Areas to Reduce Pollution Introduction.
10) Trash enclosure will be covered to minimize direct precipitation;
Use Efficient Irrigation Systems & Landscape Design.. .
11) Rain shutoff devices will be used to prevent irrigation during and after preci'pitation,
flow reducers and shut-off valves triggered by a pressure drop will be useGl to control
water loss in the event of a broken sprinkler head. . -. .
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12) Irrigation systems will be designed to fit each area's specific needs.
13) Irrigation system for landscaped areas will be monitored to reduce over irrigation.
Provide Storm Water conveyance System Stenciling and Signage.
14) Concrete stamping of storm drain inlets and catch basins with prohibitive language
-N/A;
15) Signs and prohibitive language at the public access points along cha'nnels and
creeks and building entrances -N/A. '
4.2.3 BMPs -Applicable to Individual Priority Project Categories.
Per City of Carlsbad Storm Water Requirements the following requirements shall be
incorporated into the Detached Residential Development category project: Privat~
Roads, Residential Driveway and Guest Parking, Hillside Landscaping.
Private Roads:
16) There are no private roads on the site;
Residential Driveway and Guest Parking:
17) Driveways are designed to drain into landscaping and bio-swale prior to discharging
to the storm water conveyance system.
Hillside Landscaping:
30) Slopes will be stabilized with landscaping which will incorporate native or drought
, tolerant vegetation. ' '
4.2.4 Low Impact Development (L.I.D.) .
This Project has been designed to Incorporate some of the benefits of Low Impact
Development (LID). Integrated Management Practices (IMP's) have been incorporated
into the project design as follows: ' '
• Streets/driveways designed to minimum width;
• Minimized building footprint;
• Individual lots Impervious surfaces designed to drair~ to pervious surface's prior'
to discharge; ,
• Designate an onsite location for treating building roofs & impervious surfaces.
• Education/training of homeowners to occur through printed materials including; ,
o Maintenance of filtration devices;
o Good house keeping practices i.e. pet waste, trash and debris;
o Use of fertilizers;
o Use of pesticides.
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4.2.5 Treatment Control BMPs
Treatment control BMPs will minimize a development's detrimental effect on '
water quality. Roof runoff will discharge into landscaped areas. Grass-lined swaleswili
be utilized to treat runoff from paved areas. '
The following treatment control BMPs will be implemented to address water
quality.
4.2.5.1 Bio-Filters
Bio-filtration swales are vegetated channels that receive directed flow and
convey storm water. Bio-filtration strips, also known as vegetated buffer strips, are
, vegetated sections of land over which storm water flows as overland sheet flow.
Pollutants are removed by filtration through the grass, sedimentation, adsorption
t6 soil particles, and infiltration through the soil. Swales and strips are mainly effective
at removing debris and solid particles, although some dissolved constituents are
removed by adsorption onto the soil.
4.2.5.1.1 Appropriate Applications and Site Constraints:
Swales and strips should be considered wherever site conditions and climate
.allow vegetation to be established and where flow velocities are not high enough to ..
,cause scour. Even where strips cannot be sited to accept di'rected sheet f1'ow, .
vegetated areas provide treatment of rainfall and reduce the overallimperviou$ sUrface.
Factors Affecting Preliminary Design:
Swales have two design goals: 1) maximize treatment, 2) prov'ide adequate
hydraulic function for flood routing, adequate drainage and scour prevention. Treatment
is maximized by designing the flow of water through the swale tO'be as shallow 'and long
as site constraints allow. No minimum dimensions are rE;lquired for treatment purposes"
as this could exclude swales from consideration at some sites.
To maximize treatment efficiency, strips should be designed to be as long' (fri the
direction of flow) and as flat as the site will allow. No minimum lengths or. maximum
slopes are required for treatment purposes. The area to be used for the strip should be
free of gullies or rills that can concentrate overland flow and cause ~rosion.
Vegetation mixes appropriate for various climates and locations should be"
approved by landscape staff. Some species suggested for bio:fiIter plantings, in
southern California are listed below. .
Seashore bent grass
California brome
Tufted hair grass
Blue wild rye
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Creeping wild rye
Perennial rye
Pygmy":leaf lupine
Foothill meddlers
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Red fescue
Tall (fowl) manna grass
Meadow barley
Purple needle grass
Tomcat clover
Regreen hybrid wheat grass
All of these species are capable of performing the design functions of the swales ...
Table 4.1 summarizes preliminary design factors for bio-filtration.
Table 4.1: Summary Of Bio-filtration Design Factors (Strips and Swales)
Description Applications/Siting Preliminary Design Factors
Swales are vegetated channels • Site conditions • Swales sized as a
that receive and convey storm and climate conveyance system (per
water. allow vegetation County flood routing and
Strips are vegetated buffer strips to be scour procedures) ..
over which storm water flows as established • Swales sized as a'
sheet flow. • Flow velocities conveYCince system (per
Treatment Mechanisms: not high enough County flood routing and
• Filtration through the to cause scour scour procedures)
grass • Swale water depth as ,
• Sedimentation shaliow as the site'will
• Adsorption to soil permit
particles • Strips sized as long (in • Infiltration direction' of flow) ·and flat as
Pollutants removed: the site allows
• Debris and solid • Strips should be free of
particles 'gullies or rills • Some dissolved No minimum dimensions or ' constituents •
slope restrictions for
treatment purposes
• Vegetation mix appropriate
for climates and location .
4.2.5.1.2 Construction Costs
Annual maintenance of the bio-filtration swale is estimated to cost approximately
$1,500. .'
5.0 TREATMENT CONTROL BMP SELECTION DISCUSSION
5.1 Extended Detention Basins
Extended detention basins are designed to provide temporary storage ·for runoff ,
from multiple design events.
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Advantages:
• Due to the simplicity of design, extended detention basins are· relatively easy and
inexpensive to construct and operate. . ,.
• Widespread application with sufficient capture volume can provide significant control
of channel erosion and enlargement caused by changes to flow, frequency,
relationships resulting from the increase of imper:vious cover in the watershed ..
Limitations:
• Require relatively large land area;
• Generally not prescribed for drainage areas smaller than 10 acres.
Conclusion:
Due to the site constraints and limited filtration areas available extended
detention basins are not a feasible option for the project site.
5.2 Bio swales
Bio swales (filter strips) are densely vegetated, uniformly graded areas that tread
sheet flow from adjacent impeNious surfaces. Filter strips function by slowing runoff
velocities, trapping particulate pollutants (suspended solids'and trace metals). and
providing infiltration.
Swales can be natural or manmade. Vegetated swales can seNe as part of ,a.
,stormwater drainage system and can replace curbs, gutters and stormwater syste,ms.
Advantages:
• If pr.operly designed, vegetated and manmade swales can SeNe as an aesthetic,
potentially inexpensive urban development or roadway drainage conveyance
measure with significant collateral water quality benefits;
• Bio swales are best suited to treating runoff from roads, roof downspouts and small .
parking lots;
• Relatively simply to install;
• Relatively low-maintenance;
Limitations:
• May not be appropriate for industrial sites or locations where spills may occur; ,
• Grassed swales cannot treat a very large drainage area. Large areas may be '
divided and treated using multiple swales;
, • A thick vegetative cover is needed for these practices to function properly;
• They are impractical in areas with steep topography;
• They are not effective and may even erode when flow velocities are high, if the grass
cover is not properly maintained.. ' '
• ,In some places, their use is restricted by law: many local municipalities· require curb'
and gutter systems in residential areas.
Conclus'ion:
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Vegetated swales are suited to this type of development and provide adequate
treatment.
5.3 Infiltration basins.
An infiltration basin is a shallow impoundment that is 'designed to infiltrate .
stormwater. Infiltration basins use the natural filtering ability of the soil tq remove
pollutants in stormwater runoff.
Limitations:
• Infiltration basins require a minimum soil infiltration rate 'of 0.5 inches/hbur, not
appropriate at sites with Hydrologic Soil Types C and D;
• Not suitable on fill sites or steep slopes;
• Upstream drainage area must be completely stabilized before construction;'
• Difficult to restore functioning of infiltration basins once clogged.
Conclusion:
Infiltration basins are not a feasible option for the project site.
5.4 Wet Ponds
Wet ponds are constructed basins that have a permanent pool of water
throughout the year (or at least throughout the wet season) and differ from' constructed
wetlands primarily in having a greater average depth. .' .
Advantages: . .'. " .
• If properly designed, constructed and maintained, wet basins can provide substantial'
aesthetic/recreational value and wildlife and wetland habitat;
• Due to the presence of the permanent wet pool, pro'perly designed and. maintained
wet basins can provide significant water quality improvements across a relatively
broad spectrum of constituents including dissolved nutrients. .
Limitations:
• Generally not prescribed for drainage areas smaller than 10 acres;
• Requires relatively large storage areas;
• Improperly designed or maintained ponds may result in stratification and anoxic
conditions than can promote the release of nutrients and metals.,
Conclusion:
Due to the landscape of the property and proximity to residences; wet ponds ~re
not a feasible option for the project site.
5.5 Drainage Inserts
Drainage inserts are manufactured filters or fabric placed in a drop inlet to ,
remove sediment and debris. There are a multitude of inserts of variolJs shapes and
configurations, typically falling to one of three different groups: socks, boxes and trays.
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Advantages:
• Does not require additional space as inserts as the drain inserts, are already a
component of the standard drainage systems .
• ' Easy access for inspection and maintenance.
• As there is no standing water, there is little concern for mosquito breeding.
Limitations:
• Performance is likely significantly less than treatment systems that are located at the
end of the drainage system such as ponds and vaults.
• Usually not suited for large areas or areas with trash or leaves that can plug the'
insert. ' '
Conclusion:
Drainage inserts are not a feasible option for this project site.
5.6 Hydrodynamic Separator Systems
, Hydrodynamic separators are flow-through structures with a settling, or
separation unit to remove sediments and other pollutants that are widely used in storm
water treatment. No outside power source is required, because the energy of the,
flowing water allows the sediments to efficiently separate: Depending ,on the type of
unit, this separation may be by means of swirl action or indirect filtration: Variations of
this unit have been designed to meet specific needs. Hydrodynamic separators are
most effective where the materials to be removed from runoff are heavy particulates,
which can be settled -or floatables -which can be captured, rather than solids with poor
settleability or dissolved pollutants. In addition to the standard units, some vendors,
offer supplemental features to reduce the velocity of the flow entering the system. This
increases the efficiency of the unit by allowing more sediment to settle.
Advantages:
• May provide the desired performance in less space and therefore 'less cost~
• May be more cost-effective pre-treatment devices than traditional wet or dry basins;
• Mosquito control may be less of an issue than with traditional wet basins.
Limitations:
• The area served is limited by the capacity of the largest models. , ,
• As the products come in standard sizes, the facilities will be oversized in many
cases relative to the design treatment storm, increasing cost. '
• The non-steady flows of stormwater decreases the efficiency of vortex separators,
from what may be estimated or determined from testing under constant flow. '
Conclusion:
Hydrodynamic separators are not suited to this type of developme'nt and are. not
used on this project site. '
'Stormwater Management Plan
P.N.0040
12 09717108
Masson & Associates, .Inc.
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" 6.0 OPERATION AND MAINTENANCE PROGRAM
The parking areas shall be kept free of trash and debris. The trash storage areas" ,
shall be maintained in an orderly condition. A landscaping and maintenance company
will be hired to keep all BMP's in working order. A management program will be
implemented to educate tenants about storm water management. No automobile
washing or repairing will be allowed on-site.
7.0 FISCAL RESOURCES
7.1 Mechanisms to Assure Maintenance
The project proponent shall enter an agreement with the City to maintain, repair
and replace permanent BMP's as necessary.
8~0 SUMMARY/CONCLUSIONS
This" SWMP has been prepared in accordance with the City of" Carlsbad
standards. This SWMP has evaluated and addressed the potential pollutants "associated"
with this project and their effects on water quality. A summary of the facts and"findings
associated with this project and the measures addressed by this SWMP is as "follows: "
• The beneficial uses for the receiving waters have been identified. None -of
these beneficial uses will be impaired or diminish due to the construction and
operation of this project.
• The storm drain system on site has been sized to adequately handle the flow
generated from this site.
• Post-development peak runoff flow rates and velocities from the project site
will increase insignificantly and won't affect downstream structures.
• The swales proposed as part of the project will provide mitigation of the'
increased peak flows, reducing the velocities, and providing opportunities far
infiltration and trapping particulates.
• A combination of site design, source control and treatment control BMPs are
used to maximize the treatment.
• The proposed construction and post-construction BMPs provide mitigation
measures to protect water quality, water quality objectives, and beneficial
uses to the maximum extent practicable.
13 09117108 Storm water Management Plan
P.N.0040 MCJsson & Associates, inc: "
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CERTIFICATION SHEET
This Storm Water Management Plan has been prepared under the qirection of
the following registered Civil Engineer. The Registered Civil Engineer attests to the
technical information contained herein and the engineering data upon, which
recommendations, conclusions, and decisions are based.
Scott L. Lee RCE# 70889
Stbrmw~ter Management Plan
P.N.0040
14
Date'
09117108
Masson 8. Associates, Inc.
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. . -. . -. . . .
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APPENDIX A
I INSTRUCTIONS:
This questionnaire must be completed by the applicant in advance of submitting for a developme~t applicatio~.
(subdivision and land use planning approvals and construction permits). The results of the questionnaire determine
the level of storm water pollution prevention standards applied to a proposed development or redevelopment
project. Many aspects of project site design are dependent upon the storm water pollution protections.tandards
applied to a project. .
Applicant responses to the questionnaire represent an initial assessment of the proposed 'project conditions and
impacts. City staff has responsibility for making the final assessment after ~ubmission oJ the development
application. A staff· determination that the development application is subject to more stringent storm water
standards, than initially assessed by the applicant, will result in the return of the development application as
incomplete. .' .
. If applicants"'are unsure about the meaning of a question or need help in determining how to respond to one or
more of the questions, they are advised to seek assistance from Engineering Department Development. Services
staff.
A separate completed and signed questionnaire must be submitted for each new development application
submission. Only one completed and signed questionnaire is required when multiple development applications for
the same project are submitted concurrently. In addition to this questionnaire, applicants for construc~ion permits'
must alsoc:omplete, sign and submit a Construction Activity Storm Water Standards Questionnaire ..
To address pollutants that may be generated from new development, the City requires that new developme.nt and
significant redevelopment priority projects incorporate Permanent storm Water Best Mi:lnagement ·Practice~
(BMPs) into the project design, which are described in Chapter 2 of the. City's Storm Water Standards Manual This
questionnaire should be used to categorize new development and Significant redevelopment project~ as priority or
non-priority, to determine what level of storm water standards are required or if the project is exempt.
I 1. Is your project a significant redevelopment? I.
Definition:
Significant redevelopment is defined as the creation; addition or replacement of at least 5,000 square feet of .
impervious surface on an already existing developed site. .' , '.'
Significant redevelopment includes, but is not limited to: the expansion of a building, footpdnt;' addition to or
replacement of a structure; structural development including an increase in gross floor area and/ot exterior
construction remodeling; replacement of an impervious surface that is not part of a routine maintenance activity; .
and land disturbing activities related with structural or impervious surfaces. Replacement. of impervious surfaces
includes any activity that is not part of a routine maintenance activity where impervious material(sj' are removed;
exposing underlying soil during construction. '
Note: If the Significant Redevelopment results in an increase of less than fifty percent of the impervious surfaces of
a previously existing development, and the existing development was not subject to SUSMP requirements, the·
numeric sizing criteria discussed in Table 3 of 2.3.3.4 applies only to the addition, and· not to' the entire
development.
2. If your project IS considered significant redevelopment, then please skip Section 1 and proceed with Section 2 '
3. If your project IS NOT considered significant redevelopment, then please proceed to Section 1.
21 SWMP Rev 614/08
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,~IS_E_CT~IO_N_1 ______________________ ~ ______________ ~~ ____ ~~1
NEW DEVELOPMENT
PRIORITY PROJECT TYPE YES NO' Does you' project meet one or more of the following criteria:
1. Home subdivision of 100 units or more. V Includes SFD, MFD, Condominium and Apartments
2. Residential development of 10 units or more. >< Includes SFD, MFD, Condominium and Apartments
3. Commercial and industrial develoQment greater than 100,000 square feet including Qarking areas ..
Any development on private land that is not for heavy industrial or residential uses. Example: Hospitals, X Hotels, Recreational Facilities, Shopping Malls, etc.
4. Heavy Industrial/ Industrv greater than 1 acre (NEED SIC CODES FOR PERMIT BUSINESS TYPES) '<' SIC codes 5013; 5014,5541,7532-7534, and 7536-7539
5. Automotive reQair shoQ. .y SIC codes 5013, 5014, 5541, 7532-7534, and 7536-7539
6. A New Restaurant where the land area of develoflment is 5,000 square feet or more including parking, .
areas. .)(
SIC code 5812
7. Hillside develoflment
(1) greater than 5,000 square feet of impervious surface area and (2) development will grade o'n any ><'. natural. slope that is 25% orgreater
8. Environmentally Sensitive Area (ESA). .
Impervious surface of 2,500 square feet or more located within, "directly adjacent"2 to (within 200 feet), ).(:"
or "discharging directly to,,3 receivinQ water within the ESA 1 ,
9. Parking lot.
Area of 5,000 square feet or more, or with 15 or more parking spaces, and potentially exposed to urban '>(
-runoff , . " " 10. Retail Gasoline Outlets -serving more than 100 vehicles Q.er day
Serving more than 100 vehicles per day and greater than 5,000 square feet x:
11. Streets, roads, driveways, highways, and freeways. x: Project would create a new paved surface that is 5,000 square feet or greater.
12 .. Coastal Develoflmenf Zone. ..
X. Within 200 feet of the Pacific Ocean and (1) creates more than 2500 square feet of impermeable "
surface or (2) increases impermeable surface on property by more than 10%. ,
1 Environmentally Sensitive Areas include but are not limited to all Clean Water Act Section 303(d) impaired water bodies;
areas deSignated as Areas of Special Biological Significance by the State Water Resources Control Board (Water Quality'
Control Plan for the San Diego Basin (1994) and amendments); water bodies deSignated with the RARE ben.eficial use by .
the State Water Resources Control Board (Water Quality Control Plan for the San 'Diego Basin (1994') and amendments);·
areas deSignated as preserves or their equivalent under the Multi Species Conservation Program within the Cities t;lnd Count
of San Diego; and any other equivalent environmentally sensitive areas which have been identified by the 'Copermittees.
2 "Directly adjacent" means situated within 200 feet of the environmentally sensitive area ..
3 "Discharging directly to" means outflow from a drainage conveyance system -that is, composed entirely of flows Jrom the
subject development or redevelopment site, and not commingled with flow from adjacent lands.
Section 1 Results:
If you answered YES to ANY of the questions above you have a PRIORITY project and PRIORITY project requir.ements DO
apply. A Storm Water Management Plan, prepared in accordance with City Storm Water Standards, must be submitted ~t
time of application. Please check the "MEETS PRIORITY REQUIREMENTS" box in Section 3. '
• If you answered NO to ALL of the questions above, then you are a NON-PRIORITY project and STANDARD requirements
apply. Please check the "DOES NOT MEET PRIORITY Requirements" box'in Section 3. '
SWMP Rev 6/4/08 '
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~IS_E_C_TI_O_N_2 ______________________________________ ~~~I·
SIGNIF.ICANT REDEVELOPMENT: YES NO
1. Is the project redeveloping an existing priority project type? (Priority projects Y-are defined in Section 1)
If you answered YES, please proceed to question 2.
If you answered NO, then you ARE NOT a significant redevelopment and you ARE' NOT subject. to
PRIORITY project requirements, only STANDARD requirements. Please check the "DOES NOT MEET
PRIORITY Requirements" box in Section 3 below.
2. Is the project solely limited to one of the following:
a. TrenchinQ and resurfacinQ associated with utility work?
b, Resurfacing and reconfiQurinQ existinQ surface parkinQ lots?
c. New sidewalk construction, pedestrian ramps, or bike lane on public
and/or private existing roads?
d. , Replacement of existing damaged pavement?
If you answered NO to ALL of the questions, then proceed to Question 3.
If you answered YES to ONE OR MORE of the questions then you ARE NOT a significant redevelopment.
and you ARE NOT subject to PRIORITY project requirements, only STANDARD requirements. Please
check
the "DOES NOT MEET PRIORITY Requirements" box in Section 3 below.
3. Will the development create, replace, or add at least 5,000 square feet of
impervious'surfaces on an existing development or, be located Within 200
feet of the Pacific Ocean and (1 )create more than 2500 square feet of
impermeable surface or (2) increases impermeable surface on property by ,
more than 10%?
If you answered YES, you ARE a significant redevelopment, and you ARE subject to PRIORITY project
requirements. Please check the "MEETS PRIORITY REQUIREMENTS" box in Section 3 below. '
If you answered NO, you ARE NOT a significant redevelopment, and you ARE NOT subject to ' ,
PRIORITY project requirements, only STANDARD requirements. Please check the "DOES NOT MEET
PRIORITY Requirements" box in Section 3 below.
~ls_E_c_T'_ON __ 3 ______________________________________ ~~1
Questionnaire Results:
o MY PROJECT MEETS PRIORITY REQUIREMENTS, MUST COMPLY, WITH PRIORITY
PROJECT STANDARDS AND MUST PREPARE A STORM WATER MANAGEMENT PLAN FOR
SUBMITTAL AT TIME OF APPLICATION. "
MY PROJECT DOES NOT MEET PRIORITY REQUIREMENTS AND MUSt ONLY COMPLY
WITH STANDARD STORM WATER REQUIREMENTS.
Applicant lnfonnation and Signature Box This Boxfor CilY Use'Oi1Q'
,
Address: Assessors Parcel Number(s): City Concu'rrence:, 1 .'YES 'I NO'
1 'I
Applicant Name: Applicant Title: By: '
Dale:
Applicant Signature: Date: Project ID:
SWMP Rev 6!4i08
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TableA Anticipated and, Potential Pollutants Generated by Land Use Type,
! I Ge~eraJ Pollutimf Cat::..oories 'I~i -pr-o-~-c--i----~I~~~~~~~-~l~~~--------~I-T-re-sh--~: -o~-.-gQ-~n--~I~----'~!-B-ac-re-ri-a-·~I:--~~'~, I
Categories I I Heavy Organic &. Demanding I Oil & I & I 'j'
I Sedim~nts Nub'ienis Metals Compounds Debri~ Substances I GreaSe I. Viruses pestiCides'
Detached
Residential
!?evelopment
V /\
Residential X
Attached II
Development _
x,
OJmmercial I'
Developmen( P(l} 'I, P(l) P(2) 1,x
>1DO,OOO ft2 I
I ~11
P(5) x
~R_es_tau_~_nts~I ____ ~ ____ ~1 ~~~ ___ I~x __ ~I_x ____ ~I_x __ ~I_x __ -+I _____ )
Hillside I J ,I
Development X X X I X X 1 X,' , : jl >5,000 ft2 ' ,
Parking Lots 1 P(1) 1 P(l)
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X," P(5) X I
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Streets,
1 Highways & X
Freeways
X
X :: anticipated
P :: potential
(1) A potential polluiani ij landscaping exisis on-site. -
(2) A pOiennal pollutant if the project includes uncovered parking areas.
(3.) A potential pollutant i~ land Use involves lood or animal waste products.
(4) Including petroleum hydrocarbons.
(5) Including solvents,
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l"ableB. Storm Water BMP Requirements Matrix:.
. Projects:
Detachea Residential
Development
f'l-ttached Residential
Developl]1ent
Site
Design
BMPsi1)
R
R
CommerCial Development R
'1>100,000 IF
V'-utomotive Repair Shop
Restaurants
HiIlsiCie. Development
>51000 ft2 .
Pat~ing Lots
Streets, Highways & .
Freeways R
Source
Control
BMPs(2)
R
R
R
R
R·
R·
R
R
BMP.s ApplicabJe to lndivid!1af
Priority Project Categories(3)
R R
R
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R
'" roo c>. .<
t:r.> .. £: ':0; :::> U.
r-I --
R(S) I
0:> t: Q.. .
ttl c.:> '" -0 t:.
3
~
Ji? 5: Treatment
Control
.~ BMPs(4)
s
. R = Required; select·one Dr more applicable and appropriate BMPs from the applicable steps.in Sectie>n 1I1.2.A-D. o = OptionaV or may be required by City staff. As appropriate, applicants are encouraged to ·incOrporate trsatme'rit control·
BIvl~s and BMPs applicable to individual priority project ~ategorjes into the project design. City staff may require orie Dr
, more of .these .BMPs, where appropriate. . .
. 1 S = Select one or more applicable and apf!ropriate treatment control BMPs from Section 1Il.2.
/
. (1) Refer to Section 1l1.2.A.. .
. (2) Refer to ?oecrion 1I1.2.B. . . . ", .
(3) Priority project categories must apply specific storm waier BlvlP requirements, where applicable. Priority projects'are
subject-to the requirements of all j:>ribrity project categories ±hat apply.
(4) Refer to Section 1I1.2.D: "
(5) Applies if the paved area btals >5,000 SQUare iset or with> 15 parkinQ spaces jmd is potentialln~xpbsed, to .urban runoff.
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Vegetated Swale
, D"escril'th:m
Vegeta:ted sw.aLes are ope1l; shaJ10w chBn:o.els \'I'm veg.staticm
covering the side slopes and bottom that collect and slowly
oon:veyron.aif flaw to doWll..-~ea.m discharge pam. They are,
designed tD treairun:off through fi1tering by the vegetatinnin the.
channell :filterin.gtbrougb a subsoil mat:r::b; and/qr irrE1lttation
i:t:dn the un.derly.ing sai1.s. Swales can be ~ or mznmacie,
They trap pa:t'l:iv9Jlate paTh:rtmtB (su..~endoo solids and trace
metals) 1"'l1"'fYmote infi1tratlan. andreduce the flow ve1oc...+tv of 'r"'~~ ~ .. , ~water rrmofE Vegetated ~;;cles can serve as part of a
stormwa:ter drainage system and. can replace curbs, gu:tters and.
stann sewer systems.
Cat'tifQrnia Experience
Ca11rans CQIl81:ruct~ and manitare.d six ~getated S4mes in
. soutb.em Czlifor.oia.-These. sw-cles were generally affective:in
redndng the volame and mass of poll:utaIrts inrnnaff. Even in
the areas where the aJ:ll1Ual rainfaR was only about 10 inches /"JT' ,.. J ." .... ~
the vegetation did l1JO;trequire additi-anal irrigation.. One. f&.."i:or
that s.trong1y affecteD., perlar:manre was the presence ¢ large ,
:omn.'bers of gophers at most: ofllie sites. ' The gaphers created
earthen mo.1:JI1!:k, desiroyed ve~an, mdgenerallyrednced ~ ,
effectiveness of ttre controls far 'ISS reduction.
Advantages
• If properly clesign.~ vegetated, and operated, ~~ales c;a:n
serve as an aesthe"J:i.s poteU1iaTIy ~ensive urbsn
development or roadway drainage oomey-mce measure with
significant: coJ1s:ter:al water quali:ty benefits.
Ja.'Ue\iY 2003 Callfomia Stomn!.falEr BMP Handbook ,
New Development EIild Redevelopmet,t
www.c~mphanc:books.com.
, .' "
~ '~ . , , 'TC~30 , -'
, ..
Pesign C~nsiderations ,
• T ribulary i'-.JefJ
III Slope
• W81ei Avan~bilit'j'
~ :!S>~~ .. f: I Ire" I*,*~
Ta rg:e.ted C6in:stitu:ents . o Boo rrent j. o IIJIJtriems If. '
~ TraSh , •
g 'Meals .....
&'::1 EJat'..Aerie " ".,
0"' Oil mdGrsaB$' a. o Ot~ranics' •
Le.-gerid {Re~1 fEife~tJttenas:sj ,
• Ltrw • Klfjh
j. M~di!Jm
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Vegetated',Swale
II Roadside ditches should be regarded as significant potential swale /buffer strip sites and '
should he utilized for tbis purpose whenever possible. '
Lim itati 0 ns
• Can be clifficolt to avoid channelization.
, •. May not be appropriate for industrial sites or locations where spills may occur '
J( Grassed swales cannot treat a very large drainage area. Large areas may be dhided and
treated using multiple swales,
• Atbick vegetative cover is needed for these practices to function properly.
• They are impractical in areas Vl-ith steep topography.
• They are not effective and may even erode when flow velocities are high, if t1;le grass cover is
not properly maintained.
J( In some places) their use is restricted by law: many local mmricipalities require Curb arid
, gutter systems in residential areas.
• Sviales are mores susceptible to failure if not properly maintained than other treatment
BMPs. '
Design and Sizing Guidelines ,,'.
.' Flow rate based design determmed by local requirements or sized s6 that 85%' of thearmual.
runoff volume is discharged at less than the design rainfall intensity. '
, • Swale should be designed so that the water level does not exceed 2. /srds the height of the
grass or 4 inches) which ever is less) atthe design treatment rate.
• Longitudinal slopes ,should not exceed 2.5%
• Trapezoidal channels are normally recommended but other configurations, 'such as, ,
parabolic, can also provide substantial water quality improvement and may be easi'er. to mow
than designs 'with sharp breaks in slope.
'. Swales constructed in cut are preferred, or in:fill areas that are far enoUgh froin afl, adj acent '
slope to mjnjmjze the potential for gopher damage. Do not use side slopes constructed of
:B:R which are prone to structural damage by gophers and other burrowing ani;rnals. :
• A diverse selection of low growing) plants that thrive under the specific site~ climatic, and
watering conditions should be specified. Vegetation whose grmving season corresponds to
the wet season are preferred. Drought tolerant vegetation should be considered especially
for swales that are not part of a regularly irrigated landscaped area
• 'The 'width of the swale should be determined using Manning's EquB.:t;ion using a value of
0.25 for Manning's n. ' ,
20f13 California Stormwater BMP Handbook
New Development and Redevelopment
www.cabmphandbooks.com
Jarluary 2003· '
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Vegetated Swale T.C-30
Constructian.jI1tSpecncm Con.siileruno1tS
• Include cfuections in the specifications for Use of appropriate fertilizer and sojI aIn:endJrren~
based on soil properties determined through testing and compared to ihe needs of the
vegetation requirements.
• InstaTI. swales at the time of the year when there is a rea~onable chance of successful .,'
establishmentwthoutirrigation; howe'ver, it is recognized thatrainfaTI.in a:gi.venyear m~y'
not be sufficient and temporary irrigation may be used. '
.• If sod tiles must be used, ihey should be placed so that there are no gaps between the tiles;
stagger the ends of the tiles to prevent the formation of channels along the S'vY'ale or 'strip,
• Use a roller on the sad to ensure that no air pockets form between the sod and the soil.
• Where seeds are used, erosion controls will be necessary to protect seeds for at.leaSt '715 d8.jrS
after the first rainfaTI. of the season. ' .
Performance
The literature suggests that vegetated swales represent a practical and poterrliaTI.yeffective .
technique for controlling urban runoff quality. While limited quantitative performaD.ce data ' '
exists for vegetated swales, it is ko.ovm that check dams, slight slopes, permeable soil$) dense
grass cqver) increased contact time) and smaTI. storm events aTI. contribute to successful pollutap,t ,
removal by the swale system.. Factors decreasing the effectiveness of swales mcllide compacted
soils) short runoff contact time, large storm events, frozen ground, shortgrass heights, steep'
slopes, and high runoff velocities and discharge rates. ' ,
Conventional vegetated swale designs have achieved mixed results in removIDg particulate"
pollutants. A study performed by ihe Nation-wide Urban Runoff Program (NURP) monitored
three grass swales m the IN asbington, D. C., area and found no significant improvement iii urban
runoff quality for the pollutants analyzed. However, the weak performance of tb.¢Se swales was,
attributed to the high flO"i~ velocities in the swales, soil compaction, steep slopes, and short grass,·
height.
Another proj eet in Durham, NC, monitored the perrorma:r;lCe of a carefully designed, artifici81 ,
swale that received runoff from a commercial parking lot. The project tracked 11 storms and
concluded that particulate concentrations of heavy metals (Cu, Pb, Zn, and Cd) were teducedl:jy
approximately 50 percent However, the swale proved largely ineffective for remCJiTill.gsoluble
nutrients. ' '
The effectiveness of vegetated swales can be enhanced by adding che~ da:m.S' at approxi.tnately
17 meter (50 foot) increments along iheir length (See Figure 1). These dams maximize the
retention time within the swale, decrease flow velocities, and promote particulate settling. .
F:i.naTI.y, the incorporation of vegetated filter strips parallel to the top of the channel banks.can .
help to treat sheet flows entering the SVlTale. "
Only 9 studies have been conducted on all gra~sed charmels designed for water ,quality (T~ble 1).
The data suggest relatively high removal rates for some pollutants, but negative rem9vaLs-for'
some bacteria, and fair performance for phosphorus. ' "
January 2003 Callfomia stormwater BI,IlP Handbook· ,
New Development and Redeve'!lopment
www.cabmphandbooks.com
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TC-30 Vegetated" 'Sw'ale
Table 1 Grassed swaie pollutant removal efficiency data
I Removal Effici encies (% Removal)
Study TSS TP TN NOs I Metals Bacteria Type
. Caltrans 2002 77 8 67 I 66 83-90 -33 dry swales
Goldberg 1993 67·8 4-5 -31.4 I 42-62 -100 grassed channe}"
Seattle Metro and Washington
!Department of Ecology 1992 60 45 --25 2-16 -2.5 grassed channel
Seattle Metro and Washington
tDepartment of Ecology, 1992 133 29 --25 46-73 -25 grassed channel, ,-
Wang at ai, 1981 80 -- -70-80 -dry swale . ,
Dorman et al., 1989 I 98 18 -45 37-81 -' dryswale
Harper, 1988 8'7 ' 83 84 I 80 88-90 -dryswale, ,
KeTcher et al., 1983 99 99 99 99 99 -Idryswale
!Harper,1988. 81 I 17 40 52 37-69 -twet swale
~oon, 1995 67 39 -9 -35 to 6 -M'et swale
'" , . . ,
VVhile it is difficult to distinguish between different deSigns based on the small amount of,
available data, grassed channels generally have poorer removal rates than wet and dry swales"
although some swales appear to ex.'"POrt soluble phosphorus (Harper? 1988; Koon., 1995). It is not
clear why swales ex.-port bacteria. One explanation 1S that bacteria thrive in the warm swale
soil.s.
Srting Criteria
The suitability of a swale at a site will. depend on land use, size of the area serviced, soil., type,
slope, imperviousness of the contributing watershed, and dimensions and slope of f\1.e swale ,
system (Schueler et aL, 1992). In general, swales can be used to serve areas of less than 10 acres)
with slopes no greater than 5 %. Use of natural topographic lows is encouraged and p.atural :
drainage courses should be regarded as significant local resources to be kept in use.0' oUng et al.)"
1996). " ' ,
Selection. Criteria O,,rCTCOG1 1.993)
• Comparable performance to wet basins
• Limited to treating a few acres
• Availability of water d"l11ing dry periods to maintain vegetation
• Sufficient available land area . , ,
R~search in the A:ustin area indicates that vegetated co:p,trols are Effective at :r;eino"ving pollutants '
even when, dormant Therefore, irrigation is not requ.iied to maintain groVlrtb. during dry
periods) but may be necessary only to prevent the vegetation from dying.
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Vegetated Swale Te,-3D'
The topography of the site should permit the design of a channel with appropnai:e slope and '
cross-sectional area Site topography may also dictate a need for additional structural controls.
Recommendations for longitudinal slopes range between 2 and 6 percent Flatter slopes can be'
used, if sufficient to provide adequate conveyance. Steep slopes increase flow velocity) decrease "
detention time) and may require energy dissipating a:nd grade check Steep'slopes also can be
managed using a series of check dams to terrace the swale andreduce the slope to witb.:in ' .
acceptable limits. The use of check dams with swales also promotes infiltration. '
Additional Design Guidelines
Most of the design guidelines adopted for swale design specify a minimum hydraulic residence
time of 9 minutes. This criterion is based on the resuln; of a single study conducted:in Seattle)
Washington (Seattle Metro and Washington Departm.ent of Ecology) 1992) andis n8twe1l
supported. imalysis of the data collected in that study indicates that pollutant removal at a .
residence time of 5 minutes was not significantly dif£eren~ although there is more variability:i:ri.
that data. Therefore} additional research in the design criteria for swales is needed. Substantial
pollutant removal bas also been observed for vegetated controls designed solely for conveyance '
(Barrett et al, 1998); consequently) some fle"tibilityin the design is warranted.,' ,
Many design guidelines recommend that grass be frequently mowed to mamtaiJ;l dense coverage
near the ground surface. Recent research (Colwell et al.) 2000) his shovill mO'wing frequency or
, grass height bas little or no effect on pollutant removal.
Su.mmary of Design ReCOnmte:rt.da.tifHis
1) The swale should have a length tliat provides a m:fhi.mum hydraulic residence time of
at least 10 minutes, The maximum bottom 'Width should not exceed 10 feet unless a
dividing berm is provided. The depth of flow should not exceed 2/srds the height of
the grass at the peak of the water quality design storm :i.:Q,tensity. 'The channel slope
should not exceed 2.5%.
2) A design grass height of 6 inches is recommended.
3)
5)
6)
January.2003
'.
Regardless of the recommended detention time) the swale should' be not less th.an
100 feet:in length. .
, "
The 'width of the swale should be determined using Mannirig's E.quatioll; atthe peak
of the design storm, using ~ Manning's n of 0.25. . ,.'
The swale can be sized as both a treatinentfacility for the design storm and as a
conveyance system to pass the peak hydraulic flows of the 100-year stOrIn. if it is
located "on-line." The side slopes should be no steeper than 3:1 (HV).'
Roadside ditches should be regard.ed as significant potential sw,alejbuffer strip sites
and should be utilized for this pmpose whenever possible. If flow is to be introduced
furough curb cuts) place pavement slightly above the elevation of the vegetated areas.
Curb cuts should be at least 12 inches 'Wide to preyent clogging, .
Swales m.ust be vegetated in order to provi de adequate treatment of runoff. It is
importantto maximize water contact with vegetation and the soil surface. For
general purposes, select fine) close-growing) water-r.esistant grasses. If possible,
divert runoff (other than necessary irrigation) during the p~riod of vegetation .
Califomia stormwater BMP Handbook
New Development and Redevelopment
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TC-30 Vegetated Swale
establishment Where runoff diversion is not possible) cover graded and seeded
areas with suitable erosion control materials. .
Maintenance
The useful life of a vegetated swale system is directly proportional to its maintenance frequency.
If properly designed andregolarly maintained, vegetated svvales can last indefinitely. The
maintenance obj ectives for vege~ted swale systems include keeping up the hydraulic and
removal efficiency of the channel andmainta:in:ing a dense, healthy grass cover.
Maintenance activities should include periodic mOVlrllg (with grass, never cut shorter than the
designfl.aw depth) weed con1!0~ watering during drought conditions) reseeding of bare areaS,
and clearing of debris and blockages. Cuttings should be removed from the channel.and
disposedin a local composting facility. Accumulated sediment shouid also be removed
manually to avoid concentrated flows in the swale. The application of fertilizers and pesticides
should be mjJijmal.
Another aspect of a good maintenance plan is repairing damaged areas i't'itbin a channel. For'
example, if the channel develops ruts or holes, it should be repaired utilizing a suitable soil that
is properly tamped and seeded. The grass cover should be thick; if it is not, reseed as necessary .
.Any standing water removed during the maintenance operation must be disposed to a sa:¢tary ,
sewer at an approved discharge location. Residuals (e.g., silt, grass cuttings) must be disposed
in accordance with local or State requirements. M:aintenance of grassed swales mostly involves .
maintenance of the grass or wetland plant ·cover. Typical maintenanc.e activities are .
sumtnarized belovy-:
• Inspect swales at least twice annually for erpsio~ damage to vegetation, and sediment and' ,
debris accumulation preferably at the end of the wet season to schedule summer
maintenance and before maj or fall runoff to be sure the swale is Teadyfor ·winter. However,
additional inspection after periods of heavy runoff is desirable. The. swale should be chec.:tced
for debris and litter, and areas of sediment accumulation. . '
Il Grass height and mOVlmg frequency may not have a large impact ·on pollutant removal. ,
Consequently: mowing may only be necessary once or twice a year for safety or ae$thei;ics or
to suppress weeds and woody vegetation.
• Trash tends to accumulate in S\lVale areas, particolarly along highways: The need for litter
removal is determined through periodic inspection, but litter should always be rem.oved .
prior to mowing.
• Sediment accumulating near culverts and in channels should be removed when it builds up
to 75 mm (3 in.) at any spot, or covers vegetation.· ,
• RegUlarly inspect s\lfales for pools of standing water. Swales can become a nuisance due to
mosquito breeding in standing water if obstructions develop (e.g. debris accumulation,
invasive vegetation) and/or if proper' drainage slopes are not implemented and maintained.
6of13 Callfornia Stormwater BMP Handbook
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Vegetated Swale TC-30
Cost
-Construction. Cost
little datais available to estimate the difference in. cost between various S\4'ale designs. One
study (S'WRPC, 1991) estimated the construction cost of grassed cha:onels at approximately
$0.25 per ft2. This price does not :include design costs or cont:ingencies. Brown and Schueler -
(1997) estimate these costs at approXimately 32 percent of cOILStruction costs for most . _ .
. stormwater management practices. For swales, however, these costs would-probably be ..
significantly higher s:in.ce the construc.tion costs are so low compared ·with other practices. A
more realistic estimate would be a total cost of approximately$o.so per fI:2, which compares
favDrably"with other stormwater management practices.
January 2003 Califomia Stormwater BMP Handbook
New Development and Redevelopment
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TC-30
Table 2 Swale Cost Estimate (SEWRPC, 1991)
.
Unit CPI,l.t
C'or.rJ)lo;rn·enl UI1H IiExtent I. ow Moderate . iHUgh fi~ow
'~lgbiliz:8lion I Swell.l 1 $'107 fl214 $>141 *107
Dgmobl fizatlcn .Ught
511" Prnpllmllm
Gigaringb. ...... , ......... fwm 0.5 $2,200 $3,800 $5;1\00 $1,100
Grubblng": ............. Aure 0.25 $3,8.00 $5,200 $6.eoo *1160 G~neral
8lc3valior-rt .... _ ....... YllD 372 ltil.10 !li3.70 lIili.3G !);781
19val and Till" ........ Ydll 1,210 !lO.20 $0.35 l!tJ.SS $242
51\Qs Dswlopml.lnt
881v9 gild TppsDii
Ydl 1,210 $CJ.lIO $'1.60 $i\f.\4 Sggr;j, and Mulch' .. $1.00
Sod~ ...................... Ydl 1,210 $1.20 t.l,<I(J .$;3.Em $1;452
9Hbtol.!ll .-------.li6,1·Ja
Gonllngllnchls 5,\11819 1 2!i"ilo 25% 25% $1,2711 .
Tolal --------$8,396
Source!: t8EWRPG, 11191)
Not~: MQbIllil!ltionfd~m!Jblii2:allon rQI~r.st!J IhQorgsnlmll€l!18nd plannln9,lnvoll!lltJ-in ~tllbllshlng iii vll9ateUvQ swalll.
• 8111'al9 has a 'bottom width of 1.0 foot, 9 top width of 10 feel with 1:3 side slopras, flIhd B '1 ,OOG-foot length,
., Areil cleared ::t ,top width + 10 JeefJ x ~wrale lengtll.· . .
"ArQa grubbed::: (Iopwldlh JiC s'M:lle length),
dVolumQ gl!lagv~ted = (O,Il7.:x. top wldthx BWQle depth) K Si'iB.le length {porgtJollc aross·r,eollon),
'" Are31111ed ::: {topwldlh .1-Sf!u!is,le deplh21 x s'waJe length {p3rabollc c.roslil-secllon).·
3,top width}
, Area seeded. ::; mes. cleored x 0,06.
U Area !lOdded :::; greR cle~red )( 0.5.
. 8 of i3 . California stormwater BMP Handbook
. New Development and, Redevelopment
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Vegetated Swale
TplaJ Co!!.\t
MiQ.ttiarate Hfgh ..
$274 *"'11
-
*1,900 $2,700
$1,300 fl;'I,IJ!iO
$1,378 $1,972
M24 *806
$1,~1 0 JI;'I,9JG
!t2,SlO4 1!i4!J!i6.
$Q,3E1!l $1:3,1360
i1!2,3"7 $3/4'15
$11,756 $17 ,076.
january 2003 .•
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Vegetated Swale TC-30
Table 3 Estimated Maintenance Costs (SEWRPC. 1991)
" ..... ---, -' ..
~J!II.a~!! S~ite
-, (DIll'p,th an~ "f,~'P ~dl,,!,)l .
CO-m:poneifll Un~t Cpst 1.15: fa,c,t D~plh. Onn,.. 3;·Foo\ Depth, j;·Fool Comm~~i
F'llQt 8QUQro Wr.dtal. 90ttQm WJdth, 2H::ppt
'to·Poot 'f 0iP 'WUdUj· TOil M'!ldUl
" ~ H' " LBvin Mowing ltO.B!; I 1,000 fill mov.ing lf1J.14 f lin \!!a r ropl .to.21 {lingar fuel: LBwn rniilin\gnanoo erll8={lJ:Jp
width·~ 10 Iwl)JI Jgnglh. Mow
s II! ht limos p;l r ¥Bar
GQnQral Lawn Oam Ij;Q.OO 1'1,000 fl" ygar lW:18 t IInll!ilrr~ol .t;O.2B IlInlllllrfoot LBwn m@lnhmancg an:1!8 '" (lop
. widlJ:i + 1Q flle\) xJgnglh
SwalQ OQbris: a.nd Ull9r .10.10 {Ungar foot 1~llIr lIP.i0IlinoorfQc\ ,t,O.10 ilinQEJrfpot -
RgmO\!al . -
Grass RgsggdJng'lfillh $0:30/yd' If£J.o1ll1noor !'go\ .flO.O'1 fllnsarfoot Ama mvogeialgd 1lq1J1lI1e: 1%
Mulch Bnd Ferlll12llr of lawn mllli1t~n3nOg BIWiI pgr
.. ymlr
,Program Admlnls\mtion and $0,1 GlllnBarfootlygar, 9weli~ In~psclion plus $.25 f inspsctlen
lID.iS f IInQilrfbot ,Fa.iS IlIntl:!lrfoot JnBPQct four ilmQI!l per yoor
'1[.0181 .. $0.60 1 f,lm~l!lr fool • $ OJ'!l! Jingn,rfool. -.. -~ .............. __ .
.r.:-••••
, ~.:!:.I\. .... '\j';.'
January 2003 CaliFornia storniwaler BfVPHandbook 9 of 13
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~ " TC~30 Vegetated.~wale
Maintena:nce Cost
Caltrans (2002.) estimated the expected annual maintenance cost for a swale 'with. a tribui:a{Y: ,
area of approximately 2 ha at approximately $2,700. Since almost.all maintenance consists of
mowing, the cost is fundamentally a function of the mowing frequency. Unit costs developed by .
SEWRPC are shown in Table 3. In many cases vegetated channels would be used to convey
runoff and would require periodic moV!7ffig as well, so there may be littl~ additional cost for the '
water quality component Since essentiaTIy all the activities are related to vegetation· ,"
management, no special training is required for maintenance personnel.
'References and Sources of Additional Information
Barrett, MicbP..::l E" Walsh, Patrick M:., Malin.a, Joseph F., Jr.) Charbenem; RanPall J, 1998,'
"Periormant!e of vegetative controls for treating highway runoff," ASCEJownal oj ,
Envi:ronm.entalEngineering, Vol. 124, No. ll, pp, 1121-ll28.
BrDi"fD, W., and T. Scbneler.1997. TheEconomics ojStormwater BA{Psin the Mi.d-Atlantic
Region.. Prepared for the Chesapeake Research Consortium, Edgewater, M:D, by the Center for
"Watershed Protection, Ellicott City, :MD.
Center for Watershed Protecti.on (CWP).1996. Design ojStonnwate:r Filtering Systems.'
Prepared for the Chesapeake Research Consorti~ Solomons, MD, and USEP A Regiqn V,
,Chicago, 11, byth~ Center for Watershed Protee:tion, Ellicott City, l\ID. "
Col'well, ShantiR., Homer, RichardR., and Boofu, Derek B.; 2000. Cnaracteri.za,tion 0./ '
Performance Predi·ctors andEva1:uation ojl'J.oWf.ng Practices in Biofiltration Swales., Report.
to Ki.:og County Land And Water Resources Division and others by Center for Urb'an Water
,Resources Management, Departnlent of Civil and Environm.ental Enginee:rini University· of
Washington, Seattle, WA
Dorman, M.E., J. Hartigan, R.F. Steg) and T. Quasebarfu, 1989. Retention, Detention and
Overland Flow jor PoUW:ant Removal From Highway Stormwater Runoff. 'Vol. 1. FHWA/RD
89/202. Federal Highway Administration, Washington, DC. '
Goldberg. 1993. Dayton Avenue Swale Biofiltration Study. Seattle Engineering Department,
-Seattle, W A
Harper) H. 1988. Effects ojStormwater Management Systems on GrOim.dwaterQuality.
Prepared for Florida Department of Emtironmental Regulation, Tallahassee, F1, by .
Environmental Research and Design, Inc., Orlando, FL.
, ,
. Kercher, W.C., J.e. Landon, andR. Massarelli.1983. Grassy swales-prove cost-effectiv.efor.
water pollution control. Public Works, 16: 53-55.
. Koon, J 1995. Evaluation of IIy'Tater Quality Ponds and Swciles in the IssaIWahjEast Lake
Sammamis h Basins. King C01mty Surface Water Management, Seattle, W A, and W as~gton .
Deparbnent of Ecology, Olympia, WA
Metzger, M. E., D. F. Messer, C. L. Beitia, C. M. Myers, and V. 1. Kramer. 2002~ The Dark Side'
Of Stormwater Runoff Management Disease Vectors Associated INith Structural BMPs. " . ',"
Stormwater 3(2): 24-39.0akland, P.H. 1983 . .An evaluation of stormwater pollutantrerp.ov81
10 of 13 California Stormwater BMP Handbook
New Develo-;Jment and Redevelopment.
www.ccbmphand!:;looks.com
. J9nuary 2003'
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Vegetated Swale TC-30"·
through grassed SV\Tale treatment lnProceerii.ngs ojthelntf;.rnationaJ. Sympoiiwn ofUrba:n.
Hydrology; Hydraulics a:n.d Sedimen.t Contro~ Lexington; RT pp. 173-182.. .
Occoquan Watershed Monitoring Laboratory. 1983. Final Report· Metropolitan .Washington
Urba:n. Runoff Project. Preparedfor the Metropolitan Washington C0uncil of Governments,'
Wasbington, DC, by the Occoquan Watershed Monitoring Laboratory, Manassas, VA.
Pitt, R., andJ. McLean. 1986. Toronto Area. WatershedAfanagementStrategy Study.: Humber·
River. Pilot Vvatershed Project. On'!::ru.-.i.o IYfinistry of Environmen~ Toronto, ON.' .
Schueler, T. 1997. Comparative Pollutant Removal Capability of Urban BMPs: A reanalysis. ':
Watershed Protection Teclmiques 2(2):379-383.
, Seattle Metro and 'Washington Deparb.nent of ECGlogy. 1992. Biofiltration Swale'Perjormailce.'
Recommendations a:n.dDesign. Considerations. Publication No. 657. Water POJ],uti.9n Control
Departm.en~ Seattle, WA .
Southeastern Wisconsin Regional PJanning Commission (SWRPC). +991. Costs o/Urban .
Nonpoint Source 'Water Pollution Control Measvres. Technical report no. 31. Southeastern
Wisconsin Regional Pla.rm.ing Commission, Waukesha, WI.
U.S. EPA, 19}99, Stormwater Fact Sheet Vegetated Swales, Report # 832-F-99-006 '
htt;p:/ll¥"i4"V1T.epa.goy lovnn/mtb/vegswale:Ddf. Office of Water, Washington DC. .
I '
Wang) T., b. SpyridBkis) B. Mar, and R. Horner. 1981. Transport~ Deposition and Control 0/
Heavy l\.!etalsin Highway Runoff. FHWA-'NA-RD-39-1b. University of Washington, ,
Department of Civ.il Engine.ering, Seattle, WA .
Wasbillgton State Department of Transportation, 1995, Highway RunoffManua~ W~hington:
State Department of Transportation, Olympia, Wasbington. '
Welborn., C,} andJ. VeeDhuis. 1987. Effects o/RunoffControls on the Quantity and Quality of
Urba:n. Runoffin Two Locations in Austin, 'IX. USGS Water Resources Investigations Report, .
No. 87-4004. u.s. Geological Survey, Reston, VA
Yousef, Y., M. Wanielista, H. Harper) D. Pearce, andR. Tolb,ert 1985. BestMctnagement
PraCtices: Removalo/Highway Conta.T(Linants By Roadside Swales. University of Cen:tral
Florida and Florida Department of Transportati.on, Orlando, FL. . ,
Yu, S., S. Bames, and V. Gerde. 1993. Testing ojBestManagement Practicesjor Controlling'·
Highway Runoff. FHWAJVA-93-RJ,6. Vrrg:i.nia Transportation Research CounciJ,
Charlottesville, VA .
Infarmaticm. Resom-ees
Maryland Department of the Environment (MDE). 2000. Mary la:n.d Stormwater Design. .' .
Ma:n.ual. ww·w.mde.state.md us/environment/wma/stormwatermanuat Accessed May 22, .
2001.
Reeves, E. 1994. Performance and Condition of Biofilters in the P aci.fic N orthwest,WqtershecJ.
Protection Techniques 1(3):117-119.
January 2003 Califomia stormwater BMP Handbook
New Developrnent and Redel' elopment
www.cabmphandbooks.com
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TC-30 Veg-etatedSWell e . .
Seattle Metro and Vvashington Department of ECblogy. 1992.. Biofiltration Swa,tePerjorma:n.ce.
Recommendations and Design Considerations. Publication No. 657. Seattle Metro and .
Washington Department of Ecology, Olylnpi~ WA'
USEP A1993. Guida:n.ce Sperijying Ma:n.agement 1v.feasW"es for Sources ojNonpoint Pollution in
Coastal Waters. EPA-840-B-92-002. U.S. Environmental ProtectiOl,lAgency, Office of Water. -
Washington, DC. . -.
IN atershed Management Institute (W1\11). 1997. Operation, .L~aintenance, a:n.d Ma:n.agement of
Stormwater Management Systew.s. Preparedfor U.S. Environmental Protection Agency, Office
afWater. waShington, DC, by the Watershed Management Iri~tute, IngleSide, 1ID ..
12 of 13 California Stormwater siv'lp Handbook -
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Vegetated ,Swaie
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t~llcm:
!. " I.$nglb (If <'."itlJG.~~.mI =f"'t =It""" <tmm fl'll ~n ~iw,:;m:i\mnhi(;')T ,Ilfo:~lt; llnjlllimai!ll1lGi lt~lolt. tl~ :: !l:Jtlj:!1IJ: oi dll..,® dam; (11) s.: "~ltt91J>(;0it.._<m.~ ,
YI =l~l"'~o!J.>It.~(i;~rIi~
'!.'ill = I!lx;itlil:!Jit \~jat1r <:If ~](!(;'jj Grun:ftli. ~"Ii:sIto.Mfre.~w ~ e1lUl~ Ifiln~il;;;t:lCl1i ~rlt.(!;lif.9
January 2003 Califomia Stormwater BMP Handbook
New Development ,and Redevelopment
www.cabmphandbooks.com. ,',
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'TC-30
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County of San Diego'
, Hydrology Manual,
Rainfall Isopluvials
100 Year Rainfall Eyent - 6 Hours
!sopluvial (inches)
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wrtt\.e'n pannlssion 01 SANDAG .
This prodUd may COntain information which has been reprcduc::ed' with
pennission granted by Thomas Brothers Maps.
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PROJECT No. :_--,,0,,-0-=---.4:.-0_' ..,-'-_____ -'-' __
DESCRIPTION:.?A-COSTA-c.fr':HYOiV H.OMt...:'5
CALCULATED BY :_.:.::..0!:...:.K-,-. __ ~DATE: -fltZ/OJ>
CHECKED BY : ________ DATE :-'-~~ __
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til PROJECT No. :_--={)'--'O'--'._4-_0 ___ ----,~-----
DESCRIPTION: ?A-rP5T It C fllilYOIV t..,/ &.)1 1:5
CALCULA TED BY : _.:.;..;M,-,-~-,--_-,-_DA TE: 1ft l/o?
CHECKED BY : ________ DATE :.,.... _-'----'-"--
MASSON & ASSOCIATES, INC. SHEET: 2... OF ________ _
PLANNING T ENGINEERING T SURVEYING SCALE: ___________________ ----
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MASSON & ASSOCIATES, INC.
PLANNING T ENGINEERING T SURVEYING
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0040 PROJECT No. :._~_-=-_-'--_______ ".--~
DESCRIPTION : ....::?:.....:....:.I1-_-=U!:)=~TfJ!..:...!...--=:.C..:.!tfL::./~V7.1.:::(?N.~.~.~H:...,.::.;:tl:::.,...'M~C5:::...:::.
CALCULA TED BY : --=.'~-=4.c.::...K~_---,-_DA TE: il/i./o J>
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SHEET: 3. . OF_~ ______ _
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I' : 1 200 E. WASHINGTON AVE." SUITE 200 .. ESCONDIDO .. CA 92025 .. TEL (760) 741-3570 .., FAX (760) 741 ~1186 ~: www.rT.l?sSOh....:oSsoc.com .'
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Friction Method
Solve For
Roughness Coefficient
Channel Slope
Left Side Slope
Right Side Slope
Bottom Width
Discharge
Normal Depth
Flow Area
Wetted Perimeter
Hydraulic Radius
Top Width
Critical Depth
Critical Slope
Velocity
Velocity Head
Specific Energy
Froude Number
Flow Type
Downstream Depth
Length
Number Of Steps
Upstream Depth
Profile Description
Profile Headloss
Downstream Velocity
Upstream Velocity
Normal Depth
Critical Depth
Channel Slope
911212008 2:05:22 PM
Worksheet for Bioswa/e A
Manning Formula
Normal Depth
Subcritical
0.250
0.01200 ftlft
3.00 ftlft (H:V)
3.00 ftlft (H:V)
1.00 ft
0.06 ft3/s
0.21 ft
0.33 ft2
2.30 ft
0.14 ft
2.24 ft
0.05 ft
2.68379 ftlft
0.18 ftls
0.00 ft
0.21 ft
0.08
0.00 ft
0.00 ft
o
0.00 ft
0.00 ft
Infinity ftls
Infinity ftls
0.21 ft
0.05 ft
0.01200 ftlft
Bentley Systems, Inc. Haestad Methods Solution Center . Bentley FlowMaster 108.11.00.03]·
27 Siemons Company Drive Suite 200 W Watertown, CT 06795 USA +1-20~-755-1666 . Page 1 .of· . 2
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I Critical Slope 2.68379 ftlft
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Bentley Systems, Inc. Haestad Metliods Solution Center Bentley FlowMaster [08.1.1.00;93]
I 9/1212008 2:05:22 PM 27 Siemons Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 . Page . 2 of 2
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Friction Method
Solve For
Roughness Coefficient
Channel Slope
Normal Depth
Left Side Slope
Right Side Slope
Bottom Width
Discharge
Cross Section for Bioswa/e A
Manning Formula
Normal Depth
0.250
0.01200
0.21
3.00
3.00
1.00
0.06
tuft
ft
tuft (H:V)
tuft (H:V)
ft
W/s
~~~ . ::::::::::::~::::: :::~~T
I 100ft I
Bentley Systems, Inc. Haestad Methods Solution Center BentlE1Y FiowMaster' [0.8.11.0.0.03]
9/12/20.08 2:05:35 PM 27 Siemons Company Drive Suite 200 W watertown, CT 06795 USA +1·203·755·1666 Page, l' of.' 1
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PRE-DEVELOPMENT HYDROLOGY CALCULATIONS
Storm water Management Plan
P.N.0040
15 09111108
Masson & Associates, Inc ..
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San Diego County Rational Hydrology Program
CIVILCADD/CIVILDESIGN Engineering Software,(c)1991-2005 Version 7.5
Rational method hydrology program based on
San Diego County Flood Control Division 2003 hydrology manual
Rational Hydrology Study Date: 09/17/08
********* Hydrology Study Control Information **********
LA COSTA
CARLSBAD,CA
HYDROLOGY ANALYSIS
100-YEAR FREQUENCY EVENT
PRE-DEVELOPMENT CONDITION
LOTS 408-409
Program License Serial Number 4065
Rational hydrology study storm event year is 100.0
English (in-Ib) input data Units used
Map data precipitation entered:
6 hour, precipitation(inches) = 2.800
24 hour precipitation(inche~) = 5.100
P6/P24 = 54.9%
San Diego hydrology manual 'C' values used
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 1.011 to Point/Station 1.012
**** INITIAL AREA EVALUATION ****
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 1.000
Decimal fraction soil group D = 0.000
[LOW DENSITY RESIDENTIAL
(1.0 DU/A or Less )
Impervious value, Ai = 0.100
Sub-Area C Value = 0.360
Initial subarea total flow distance = 50.000(Ft.)
Highest elevation = 134.000(Ft.)
Lowest elevation = 1 06.000(Ft.)
Elevation difference = 28.000(Ft.) Slope = 56.000 %
Top of Initial Area Slope adjusted by User to 30.000 %
INITIAL AREA TIME OF CONCENTRATION CALCULATIONS:
The maximum overland flow distance is 100.00 (Ft)
for the top area slope value of 30.00 %, in a development type of
1.0 DU/A or Less
In Accordance With Figure 3-3
Initial Area Time of Concentration = 4.29 minutes
TC = [1.8*(1.1-C)*distance(Ft.)A.5)/(% slopeA(1/~)]
TC = [1.8*(1.1-0.3600)*( 100.000A.5)/( 30.000A(1/3)]= 4.29
Calculated TC of 4.287 minutes is less than 5 minutes,
resetting TC to 5.0 minutes for rainfall intensity calculations
Rainfall intensity (I) = 7.377(ln/Hr) for a 100.0 year storm
Effective runoff coefficient used for area (Q=KCIA) is C = 0.360
Subarea runoff = 0.019(CFS)
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Total initial stream area = 0.007(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++~+++++++++++
Process from Point/Station 1.012 to Point/Station 1.012
**** CONFLUENCE OF MINOR STREAMS ****
Along Main Stream number: 1 in normal stream number 1
Stream flow area = 0.007(Ac.)
Runoff from this stream = 0.019(CFS)
Time of concentration = 4.29 min.
Rainfall intensity = 7.377(ln/Hr)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 1.012 to Point/Station 1.012
**** USER DEFINED FLOW INFORMATION AT A POINT ****
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 1.000
Decimal fraction soil group D = 0.000
[LOW DENSITY RESIDENTIAL
(1.0 DU/A or Less )
Impervious value, Ai = 0.100
Sub-Area C Value = 0.360
Rainfall intensity (I) = 7.062(ln/Hr) for a 100.0 year storm
User specified values are as follows:
TC = 5.35 min. Rain intensity = 7.06(1n/Hr)
Total area = 0.220(Ac.) Total runoff = 0.559(CFS)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 1.012 to Point/Station 1.012
**** CONFLUENCE OF MINOR STREAMS ****
Along Main Stream number: 1 in normal stream number 2
Stream flow area = 0.220(Ac.)
Runoff from this stream = 0.559(CFS)
Time of concentration = 5.35 min.
Rainfall intensity = 7.062(1n/Hr)
Summary of stream data:
Stream Flow rate TC Rainfall Intensity
No. (CFS) (min) (ln/Hr)
0.019 4.29 7.377
2 0.559 5.35 7.062
Qmax(1) =
1.000 * 1.000 * 0.019) +
1.000 * 0.801 * 0.559) + = 0.466
Qmax(2) =
0.957 * 1.000 * 0.019) +
1.000 * 1.000 * 0.559) + = 0.577
Total of 2 streams to confluence:
Flow rates before confluence point:
0.019 0.559
Maximum flow rates at confluence using above data:
0.466 0.577
Area of streams before confluence:
0.007 0.220
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Results of confluence:
Total flow rate = 0.577(CFS)
Time of concentration = 5.350 min.
Effective stream area after confluence = O.227(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++7+++++++++++++++++++
Process from PointlStation 1.012 to PointlStation 1 :013
**** IRREGULAR CHANNEL FLOW TRAVEL TIME ****
Estimated mean flow rate at midpoint of channel = O.797(CFS)·
Depth of flow = 0.264(Ft), Average velocity = 4.848(Ftls)
******* Irregular Channel Data ***********
Information entered for subchannel number 1 :
Point number 'X' coordinate 'Y' coordinate
1 0.00 0.75
2 0.22 0.22
3 0.75 0.00
4 1.28 0.22
5 1.50 0.75
Manning's 'N' friction factor = 0.016
Sub-Channel flow = 0.797(CFS)
flow top width = 1.097(Ft.)
I velocity= 4.848(Ftls)
area = O.164(Sq.Ft)
Froude number = 2.207
Upstream point elevation = 106.000(Ft.)
Downstream point elevation = 97.500(Ft.)
Flow length = 210.000(Ft.)
Travel time = 0.72 min.
Time of concentration = 6.07 min.
Depth of flow = 0.264(Ft.)
Average velocity = 4.848(Ftls)
Total irregular channel flow = 0.797(CFS)
Irregular channel normal depth above invert elev. = 0.264(Ft)
Average velocity of channel(s) = 4.848(Ftls)
Adding area flow to channel
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
. Decimal fraction soil group C = 1 .000
Decimal fraction soil group D = 0.000
[LOW DENSITY RESIDENTIAL
(1.0 Du/A or Less )
Impervious value, Ai = 0.100
Sub-Area C Value = 0.360
Rainfall intensity = 6.509(ln/Hr) for a 100.0 year storm-
Effective runoff coefficient used for total area
(Q=KCIA) is C = 0.360 CA = 0.144
Subarea runoff = 0.360{CFS) for 0.173(Ac.)
Total runoff = 0.937(CFS) Total area = 0.400(Ac.)
Depth of flow = 0.281 (Ft.), Average velocity = 5.113(Ftls)
End of computations, total study area = 0.400 (Ac.)
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San Diego County Rational Hydrology Program
CIVILCADD/CIVILDESIGN Engineering Software,(c)1991-2005 Version 7.5
Rational method hydrology program based on
San Diego County Flood Control Division 2003 hydrology manual
Rational Hydrology Study Date: 09/17108
********* Hydrology Study Control Information **********
LA COSTA
CARLSBAD,CA
HYDROLOGY ANALYSIS
100-YEAR FREQUENCY EVENT
PRE-DEVELOPMENT CONDITION
LOTS 408-409
Program License Serial Number 4065
Rational hydrology study storm event year is 100.0
English (in-Ib) input data Units used
Map data precipitation entered:
6 hour, precipitation(inches) = 2.800
24 hour precipitation(inches) = 5.100
P6/P24 = 54.9%
San Diego hydrology manual'C' values used
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 1.011 to Point/Station 2.011
**** INITIAL AREA EVALUATION ****
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 1.000
Decimal fraction soil group D = 0.000
[LOW DENSITY RESIDENTIAL
(1.0 DUiA or Less )
Impervious value, Ai = 0.100
Sub-Area C Value = 0.360 '
Initial subarea total flow distance = 38.000(Ft.)
Highest elevation = 134.000(Ft.)
Lowest elevation = 126 .400(Ft.)
Elevation difference = 7.600(Ft.) Slope = 20;000 %
INITIAL AREA TIME OF CONCENTRATION CALCULATIONS:
The maximum overland flow distance is 100.00 (Ft)
for the top area slope value of 20.00 %, in a development type of
1.0 DUiA or Less
In Accordance With Figure 3-3
Initial Area Time of Concentration = 4.91 minutes
TC = [1.8*( 1.1-C)*distance(Ft.)A .5)/(% slopeA(1/3)l
TC = [1.8*(1.1-0.3600)*( 100.000A.5)/( 20.000A(1/3)]= 4.91
Calculated TC of 4.907 minutes is less than' 5 minutes, .
resetting TC to 5.0 minutes for rainfall intensity calculations
Rainfall intensity (I) = 7.377(ln/Hr) for a 100.0 year storm
Effective runoff coefficient used for area (Q=KCIA) is C = 0.360
Subarea runoff = 0.053(CFS) ,
Total initial stream area = 0.020(Ac.)
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++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ .
Process from Point/Station 2.011 to Point/Station 2.012
**** IRREGULAR CHANNEL FLOW TRAVEL TIME ****
Estimated mean flow rate at midpoint of channel = 0.345(CFS)
Depth of flow = 0.094(Ft.), Average velocity = 0.972(Ft/s)
******* Irregular Channel Data ****.*******
Information entered for subchannel number 1 :
Point number 'X' coordinate 'V' coordinate
1 0.00 0.50
2 20.00 0.00
3 40.00 0.50
Manning's 'N' friction factor = 0.045
Sub-Channel flow = 0.345(CFS)
flow top width = 7.540(Ft.)
, velocity= 0.972(Ft/s)
area = 0.355(Sq.Ft)
Froude number = 0.789
. Upstream point elevation = 126.400(Ft.)
Downstream point elevation = 120.700(Ft.)
Flow length = 112.000(Ft.)
Travel time = 1.92 min.
Time of concentration = 6.83 min.
Depth of flow = 0.094(Ft.)
Average velocity = 0.972(Ft/s)
Total irregular channel flow = 0.345(CFS)
Irregular channel normal depth above invert elev. = 0.094(Ft.)
Average velocity of channel(s) = 0.972(Ft/s)
Adding area flow to channel
User specified 'C' value of 0.390 given for subarea
Rainfall intensity = 6.034(ln/Hr) for a 100.0 year storm
Effective runoff coefficient used for total area
(Q=KCIA) is C = 0.390 CA = 0.094
Subarea runoff = 0.512(CFS) for 0.220(Ac.)
Total runoff = 0.565(CFS) Total area = 0.240(Ac.)
Depth of flow = 0.113(Ft.), Average velocity = 1.099(Ft/s)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 2.012 to Point/Station 2.012
**** CONFLUENCE OF MINOR STREAMS ****
Along Main Stream number: 1 in normal stream number 1
Stream flow area = 0.240(Ac.)
Runoff from this stream = 0.565(CFS)
Time of concentration = 6.83 min.
Rainfall intensity = 6.034(ln/Hr)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 2.011 to Point/Station . 2.011
**** USER DEFINED FLOW INFORMATION AT A POINT ****
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 1.000
Decimal fraction soil group D = 0.000
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[LOW DENSITY RESIDENTIAL
(1.0 DU/A or Less )
Impervious value, Ai = 0.100
Sub-Area C Value = 0.360
Rainfall intensity (I) = 5.963(1n/Hr) for a 100.0 year storm
User specified values are as follows:
TC = 6.95 min. Rain intensity = 5.96(ln/Hr)
Total area = 0.910(Ac.) Total runoff = 2.537(CFS)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 2.011 to Point/Station 2.012
**** IRREGULAR CHANNEL FLOW TRAVEL TIME ****
Depth of flow = 0.246(Ft), Average velocity = 4.902(Ft/s)
******* Irregular Channel Data ***********
Information entered for subchannel number 1 :
Point number 'X' coordinate 'Y' coordinate
1 0.00 0.90
2 30.00 0.14
3 31.65 0.00
4 31.75 0.50
Manning's 'N' friction factor = Q.016
Sub-Channel flow = 2.537(CFS)
flow top width = 5.879(Ft.)
, velocity= 4.902(Ft/s)
area = 0.518(Sq.Ft)
Froude number = 2.911
Upstream point elevation = 124.500(Ft.)
Downstream point elevation = 120. 700(Ft.)
Flow length = 51.000(Ft.)
Travel time = 0.17 min.
Time of concentration = 7.13 min.
Depth of flow = 0 .246(Ft.)
Average velocity = 4.902(Ft/s)
Total irregular channel flow = 2.537(CFS)
Irregular channel normal depth above invert elev. = 0.246(Ft.)
Average velocity of channel(s) = 4.902(Ft/s)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 2.011 to Point/Station 2.012 .
**** CONFLUENCE OF MINOR STREAMS ****
Along Main Stream number: 1 in normal stream number 2
Stream flow area = 0.910(Ac.)
Runoff from this stream = 2.537(CFS)
Time of concentration = 7.13 min.
Rainfall intensity = 5.869(ln/Hr)
Summary of stream data:
Stream Flow rate TC
No. (CFS) (min)
.1 0.565 6.83
2 2.537 7.13
Qmax(1) =
1.000 * 1.000 *
Rainfall Intensity
(In/Hr)
6.034
5.869
0.565) +
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1.000 * 0.958 *
Qmax(2) =
0.973 * 1.000 *
1.000 * 1.000 *
2.537) + =
0.565) +
2.537) + =
Total of 2 streams to confluence:
Flow rates before confluence point:
0.565 2.537
2.995
3.086
Maximum flow rates at confluence using above data:
2.995 3.086
Area of streams before confluence:
0.240 0.910
Results of confluence:
Total flow rate = 3.086(CFS)
Time of concentration = 7.127 min.
Effective stream area after confluence = 1.150(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 2.012 to Point/Station 2.033
**** IRREGULAR CHANNEL FLOW TRAVEL TIME ****.
Depth of flow = 0.257(Ft.), Average velocity = 5.250(Ft/s)
******* Irregular Channel Data ***********
Information entered for subchannel number 1 :
Point number 'X' coordinate 'V' coordinate
1 0.00 0.90
2 30.00 0.14
3 31.65 0.00
4 31.75 0.50
Manning's 'N' friction factor = 0.016
Sub-Channel flow = 3.086(CFS)
flow top width = 6.336(Ft.)
, velocity= 5.250(Ft/s)
area = 0.588(Sq.Ft)
Froude number = 3.037
Upstream point elevation = 120.700(Ft.)
Downstream point elevation = 109.000(Ft.)
Flow length = 147.000(Ft.)
Travel time = 0.47 min.
Time of concentration = 7.59 min.
Depth of flow = 0.257(Ft.)
Average velocity = 5.250(Ft/s)
Total irregular channel flow = 3.086(CFS)
Irregular channel normal depth above invert elev. = 6.257(Ft.)
Average velocity of channel(s) = 5.250(Ft/s)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++t+
Process from Point/Station 2.012 to Point/Station 2.033
**** CONFLUENCE OF MINOR STREAMS ****
Along Main Stream number: 1 in normal stream number 1
Stream flow area = 1. 150(Ac.)
Runoff from this stream = 3.086(CFS)
Time of concentration = 7.59 min.
Rainfall intensity = 5.634(ln/Hr)'
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++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 2.031 to Point/Station 2.032
**** INITIAL AREA EVALUATION ****
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 1.000
Decimal fraction soil group D = 0.000
[LOW DENSITY RESIDENTIAL
(1.0 DUiA or Less )
Impervious value, Ai = 0.100
Sub-Area C Value = 0.360
Initial subarea total flow distance = 28.000(Ft.)
Highest elevation = 118.400(Ft.)
Lowest elevation = 117. 700(Ft.)
Elevation difference = 0.700(Ft.) Slope = 2.500 %
INITIAL AREA TIME OF CONCENTRATION CALCULATIONS:
The maximum overland flow distance is 100.00 (Ft)
for the top area slope value of 2.50 %, in a development type of
1.0 DU/A or Less
In Accordance With Figure 3-3
Initial Area Time of Concentration = 9.81 minutes
TC = [1.8*(1.1-C)*distance(Ft.)A.5)/(% slopeA(1/3)]
TC = [1.8*(1.1-0.3600)*( 100.000A.5)/( 2.500A(1/3)]= 9.81
Rainfall intensity (I) = 4.775(ln/Hr) for a 100.0 year storm
Effective runoff coefficient used for area (Q=KCIA) is C = 0.360
Subarea runoff = 0.052(CFS)
Total initial stream area = 0.030(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 2.032 to Point/Station 2.033
**** IRREGULAR CHANNEL FLOW TRAVEL TIME ****-
Estimated mean flow rate at midpoint of channel = 0.464(CFS)
Depth of flow = 0.092(Ft.), Average velocity = 1.366(Ft/s).
******* Irregular Channel Data ***********
Information entered for subchannel number 1 :
Point number 'X' coordinate 'Y' coordinate
1 0.00 0.50
2 20.00 0.00
3 40.00 0.50
Manning's 'N' friction factor = 0.045
Sub-Channel flow = 0.464(CFS)
flow top width = 7.375(Ft.)
, velocity= 1.366(Ft/s)
area = 0.340(Sq.Ft)
Froude number = 1.121
Upstream pOint elevation = 117. 700(Ft.)
Downstream point elevation = 109.000(Ft.)
_ Flow length = 84.000(Ft.)
Travel time = 1.02 min.
Time of concentration = 10.84 min.
Depth of flow = 0.092(Ft.)
Average velocity = 1.366(Ft/s)
Total irregular channel flow = 0.464(CFS)
Irregular channel normal depth above invert elev. = 0.092(Ft.)
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Average velocity of channel(s) = 1.366(Ftls)
Adding area flow to channel
User specified 'C' value of 0.450 given for subarea
Rainfall intensity = 4.479(ln/Hr) for a 100.0 year storm
Effective runoff coefficient used for total area
(Q=KCIA) is C = 0.450 CA = 0.212
Subarea runoff = 0.896(CFS) for 0.440(Ac.)
Total runoff = 0.947(CFS) Total area = 0.470(Ac.)
Depth of flow = 0.120(Ft.), Average velocity = 1.632(Ftls)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from PointlStation 2.032 to PointlStation 2.033
**** CONFLUENCE OF MINOR STREAMS ****
Along Main Stream number: 1 in normal stream number 2
Stream flow area = 0.470(Ac.)
Runoff from this stream = 0.947(CFS)
Time of concentration = 10.84 min.
Rainfall intensity = 4.4 79(ln/Hr)
Summary of stream data:
Stream Flow rate TC Rainfall Intensity
No. (CFS) (min) (ln/Hr)
3.086 7.59 5.634
2 0.947 10.84 4.479
Qmax(1) =
1.000 * 1.000 * 3.086) +
1.000 * 0.701 * 0.947) + = 3.750
Qmax(2) =
0.795 * 1.000 * 3.086) +
1.000 * 1.000 * 0.947) + = 3.401
Total of 2 streams to confluence:
Flow rates before confluence point:
3.086 0.947
Maximum flow rates at confluence using above data:
3.750 3.401 '
Area of streams before confluence:
1.150 0.470
Results of confluence:
Total flow rate = 3.750(CFS)
Time of concentration = 7.594 min.
Effective stream area after confluence =
End of computations, total study area =
1.620(Ac.)
1.620 (Ac.)
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POST-DEVELOPMENT HYDROLOGY CALCULATIONS
Stormwater Management Plan
, P.N.0040
16 , .", .0911'1108 '
Masson & Associates, Inc;,
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San Diego County Rational Hydrology Program ,
CIVILCADD/CIVILDESIGN Engineering Software,(c)1991-2005 Version 7.5
Rational method hydrology program based oil
San Diego County Flood Control Division 2003 hydrology manual
Rational Hydrology Study Date: 09/17/08
********* Hydrology Study Control Information **********
LA COSTA
CARLSBAD,CA
HYDROLOGY ANALYSIS
100-YEAR FREQUENCY EVENT
POST-DEVELOPMENT CONDITION
LOTS 408-409
Program License Serial Number 4065
Rational hydrology study storm event year is 100.0
English (in-Ib) input data Units used
Map data precipitation entered:
6 hour, precipitation(inches) = 2.800
24 hour precipitation(inches) = 5.100
P6/P24 = 54.9%
San Diego hydrology manual 'C' values used
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 1.011 to Point/Station 1.012
**** INITIAL AREA EVALUATION ****
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 1.000
Decimal fraction soil group D = 0.000
[LOW DENSITY RESIDENTIAL
(1.0 DU/A or Less )
Impervious value, Ai = 0.100
Sub-Area C Value = 0.360
Initial subarea total flow distance = 31.000(Ft.)
Highest elevation = 125.500(Ft.)
Lowest elevation = 106.000(Ft.)
Elevation difference = 19.500(Ft.) Slope = 62.903 %
Top of Initial Area Slope adjusted by User to 30.000 %
INITIAL AREA TIME OF CONCENTRATION CALCULATIONS:
The maximum overland flow distance is 100.00 (Ft)
for the top area slope value of 30.00 %, in a development type of
1.0 DUIA or Less .
In Accordance With Figure 3-3 .
Initial Area Time of Concentration = 4.29 minutes
TC = [1.8*(1.1-C)*distance(Ft.)".5)/(% slope"(1/3)]
TC = [1.8*(1.1-0.3600)*( 100.000".5)/( 30.000"(113)]= 4.29
Calculated TC of 4.287 minutes is less than 5 minutes,
resetting TC to 5.0 minutes for rainfall intensity calculations
,Rainfall intensity (I) = 7.377(ln/Hr) for a 100.0 year storm
Effective runoff coefficient used for area (Q=KCIA) is C = 0.360
Subarea runoff = 0.013(CFS)
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Total initial stream area = 0.005(Ac.)
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++f++ .
Process from Point/Station 1.011 to Point/Station 1.012
**** CONFLUENCE OF MINOR STREAMS ****
Along Main Stream number: 1 in normal stream number 1
Stream flow area = 0.005(Ac.)
Runoff from this stream = 0.013(CFS)
Time of concentration = 4.29 min.
Rainfall intensity = 7.377(ln/Hr)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 1.012 to Point/Station 1.012
**** USER DEFINED FLOW INFORMATION AT A POINT ****
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 1.000
Decimal fraction soil group D = 0.000
[LOW DENSITY RESIDENTIAL
(1.0 DU/A or Less )
Impervious value, Ai = 0.100
Sub-Area C Value = 0.360
Rainfall intensity (I) = 6.987(ln/Hr) for a 100.0 year storm
. User specified values are as follows:
TC = 5.44 min. Rain intensity = 6.99(1n/Hr)
Total area = 0.160(Ac.) Total runoff = 0.402(CFS)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 0'
Process from Point/Station 1.012 to Point/Station 1.012
**** CONFLUENCE OF MINOR STREAMS ****
Along Main Stream number: 1 in normal stream number 2
Stream flow area = 0.160(Ac.)
Runoff from this stream = 0.402(CFS).
Time of concentration = 5.44 min.
Rainfall intensity = 6.987(ln/Hr)
Summary of stream data:
Stream Flow rate TC Rainfall Intensity
No. (CFS) (min) (In/Hr)
1 0.013 4.29 7.377
2 0.402 5.44 6.987
Qmax(1) =
1.000 * 1.000 * 0.013)+
1.000 * 0.788 * 0.402) + = 0.330
Qmax(2) =
0.947 * 1.000 * 0.013) +
1.000 * 1.000 * 0.402) + = 0.415
Total of 2 streams to confluence:
Flow rates before confluence point:
0.013 0.402
Maximum flow rates at confluence using above data:
0.330 0.415
Area of streams before confluence:
0.005 0.160
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Results of confluence:
Total flow rate = 0.415(CFS)
Time of concentration = 5.440 min.
Effective stream area after confluence = 0 .165(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from PointiStation 1 .012 to PointiStation 1.013
**** IRREGULAR CHANNEL FLOW TRAVE~ TIME **** .
Estimated mean flow rate at midpoint of channel = 0.597(CFS)
Depth of flow = 0.235(Ft.), Average velocity = 4.485(Ftls)
******* Irregular Channel Data ***********
Information entered for subchannel number 1 :
Point number 'X' coordinate 'Y' coordinate
1 0.00 0.75
2 0.22 0.22
3 0.75 0.00
4 1.28 0.22
5 1.50 0.75
Manning's 'N' friction factor = 0.016
Sub-Channel flow = 0.597(CFS)
flow top width = 1.073(Ft.)
, velocity= 4.485(Ftls)
area = 0.133(Sq.Ft)
Froude number = 2.244
Upstream point elevation = 106.000(Ft.)
Downstream point elevation = 97 .000(Ft.)
Flow length = 210.000(Ft.)
Travel time = 0.78 min.
Time of concentration = 6.22 min.
Depth of flow = 0.235(Ft.)
Average velocity = 4.485(Ftls)
Total irregular channel flow = 0.597(CFS)
Irregular channel normal depth above invert elev. = O.235(Ft.)
Average velocity of channel(s) = 4.485(Ftls)
Adding area flow to channel
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Decimal fraction s'oil group C = 1.000
Decimal fraction soil group D = 0.000
[LOW DENSITY RESIDENTIAL
(1.0 DU/A or Less )
Impervious value, Ai = 0.100
Sub-Area C Value = 0.360
Rainfall intensity = 6.408(ln/Hr) for a 100.0 year storm
Effective runoff coefficient used for total area
(Q=KCIA) is C = 0.360 CA = 0.112
Subarea runoff = 0.301 (CFS) for 0.145(Ac.)
Total runoff = 0.715(CFS) Total area = 0.310(Ac.)
Depth of flow = 0.251 (Ft.), Average velocity =. 4.767(Ftls)
End of computations, total study area = 0.310 (Ac.)
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San Diego County Rational Hydrology Program
CIVILCADD/CIVILDESIGN Engineering Software,(c)1991-2005 Version 7.5
Rational method hydrology program based on
San Diego County Flood Control Division 2003 hydrology manual
Rational Hydrology Study Date: '09/17/08
********* Hydrology Study Control Information **********
LA COSTA
CARLSBAD, CA
HYDROLOGY ANALYSIS
100-YEAR FREQUENCY EVENT
POST-DEVELOPMENT CONDITION
LOTS 408-409
Program License Serial Number 4065
Rational hydrology study storm event year is 100.0
English (in-Ib) input data Units used
Map data precipitation entered:
6 hour, precipitation (inches) = 2.800
24 hour precipitation(inches) = 5.100
P6/P24 = 54.9%
San Diego hydrology manual 'C' values used
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 2.011 to Point/Station 2.012
**** INITIAL AREA EVALUATION ****
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 1.000
Decimal fraction soil group 0 = 0.000
[HIGH DENSITY RESIDENTIAL
(24.0 DU/A or Less )
Impervious value, Ai = 0.650
Sub-Area C Value = 0.690
Initial subarea total flow distance = 11.000(Ft.)
Highest elevation = 126.000(Ft.)
Lowest elevation = 125.500(Ft.)
Elevation difference = 0.500(Ft.) Slope = 4.545 %
INITIAL AREA TIME OF CONCENTRATION CALCULATIONS:
The maximum overland flow distance is 95.00 (Ft)
for the top area slope value of 4.54 %, in a development type of
24.0 DUiA or Less
In Accordance With Figure 3-3
Initial Area Time of Concentration = 4.34 minutes
TC = [1.8*( 1.1-C)*distance(Ft.)" .5)/(% slope"(1/3)]
TC = [1.8*(1.1-0.6900)*( 95.000".5)/( 4.545"(1/3)]= 4'.34
Calculated TC of 4.343 minutes is less than 5 minutes,
resetting TC to 5.0 minutes for rainfall intensity calculations
Rainfall intensity (I) = 7.377(ln/Hr) for a 100.0 year storm
Effective runoff coefficient used for area (Q=KCIA)'is C = 0.690
Subarea runoff = 0.204(CFS) .
Total initial stream area = 0.040(Ac.)
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++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 2.012 to Point/Station 2.021
**** PIPEFLOW TRAVEL TIME (User specified size) ****
Upstream point/station elevation = 124.500(Ft.)
Downstream pOint/station elevation = 123.300(Ft.)
Pipe length = 117.00(Ft.) Manning's N = 0.013
No. of pipes = 1 Required pipe flow = 0.204(CFS)
Given pipe size = 6.00(ln.)
Calculated individual pipe flow = 0.204(CFS)
Normal flow depth in pipe = 2.4B(ln.)
Flow top width inside pipe = 5.91 (In.)
Critical Depth = 2.71(ln.)
Pipe flow velocity = 2.65(Ft/s)
Travel time through pipe = 0.74 min.
Time of concentration (TC) = 5.0B min.
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 2.012 to Point/Station 2.021
**** CONFLUENCE OF MINOR STREAMS ****
Along Main Stream number: 1 in normal stream number 1
Stream flow area = 0.040(Ac.)
Runoff from this stream = 0.204(CFS)
Time of concentration = 5.0B min.
Rainfall intensity = 7.304(ln/Hr)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 2.022 to Point/Station 2.021
**** INITIAL AREA EVALUATION ****
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 1.000
Decimal fraction soil group D = 0.000
[HIGH DENSITY RESIDENTIAL
(24.0 DU/A or Less )
Impervious value, Ai = 0.650
Sub-Area C Value = 0.690
Initial subarea total flow distance = 30.000(Ft.)
Highest elevation = 126.000(Ft.)
Lowest elevation = 125.500(Ft.)
Elevation difference = 0.500(Ft.) Slope = 1.667 %
INITIAL AREA TIME OF CONCENTRATION CALCULATIONS:
The maximum overland flow distance is 75.00 (Ft)
for the top area slope value of 1.67 %, in a development type of
24.0 DU/A or Less
In Accordance With Figure 3-3
Initial Area Time of Concentration = 5.39 minutes
'TC = [1.B*(1.1-C)*distance(Ft.)".5)/(% slope"(1/3)]
TC = [1.B*(1.1-0.6900)*( 75.000".5)/( 1.667"(1/3)]= 5.39
Rainfall intensity (I) = 7.02B(ln/Hr) for a 100.0 year storm
Effective runoff coefficient used for area (Q=KCIA) is C = 0.690
Subarea runoff = 0.145(CFS) ,
Total initial stream area = 0.030(Ac.)
+++++++++++++++++++++++++++++++++++++++++++++++++++++'+++++++++++.++++:1"+
Process from Point/Station 2.022 to Point/Station 2.021 .
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**** CONFLUENCE OF MINOR STREAMS ****
Along Main Stream number: 1 in normal stream number 2
Stream flow area = 0.030(Ac.)
Runoff from this stream = 0.145(CFS)
Time of concentration = 5.39 min.
Rainfall intensity = 7.028(ln/Hr)
Summary of stream data:
Stream Flow rate TC Rainfall Intensity
No. (CFS) (min) (In/Hr)
1 0.204 5.08 7.304
2 0.145 5.39 7.028
Qmax(1) =
1.000 * 1.000 * 0.204) +
1.000 * 0.942 * 0.145) + = 0.341
Qmax(2) =
0.962 * 1.000 * 0.204) +
1.000 * 1.000 * 0.145) + = 0.341
Total of 2 streams to confluence:
Flow rates before confluence point:
0.204 0.145
Maximum flow rates at confluence using above data:
0.341 0.341
Area of streams before confluence:
0.040 0.030
Results of confluence:
Total flow rate = 0.341 (CFS)
Time of concentration = 5.390 min.
Effective stream area after confluence = 0.070(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
" Process from Point/Station 2.021 to Point/Station 2.031
**** PIPEFLOW TRAVEL TIME (User specified size) ****
Upstream point/station elevation = 123.300(Ft.)
Downstream point/station elevation = 122.220(Ft.)
Pipe length = 81.00(Ft.) Manning's N = 0.013
No. of pipes =: 1 Required pipe flow = 0.341(CFS)
Given pipe size = 6.00(ln.)
Calculated individual pipe flow = 0.341 (CFS)
Normal flow depth in pipe = 3.09(ln.)
Flow top width inside pipe = 6.00(ln.)
Critical Depth = 3.56(ln.)
Pipe flow velocity = 3.34(Ft/s)
Travel time through pipe = 0040 min.
Time of concentration (TC) =5.79 min.
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++t++++++++++
Process from Point/Station 2.021 to Point/Station "2.031;
**** CONFLUENCE OF MINOR STREAMS *-1<**
Along Main Stream number: 1 in normal stream number 1
Stream flow area = 0.070(Ac.)
Runoff from this stream = 0.341 (CFS)
Time of concentration = 5.79 min.
Rainfall intensity = 6.708(ln/Hr)
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++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 1.011 to Point/Station 2.031
**** INITIAL AREA EVALUATION ****
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 1.000
Decimal fraction soil group D = 0.000
[HIGH DENSITY RESIDENTIAL
(24.0 DU/A or Less )
Impervious value, Ai = 0.650
Sub-Area C Value = 0.690 .
Initial subarea total flow distance = 17.000(Ft.)
Highest elevation = 125.500(Ft.)
Lowest elevation = 124.1 OO(Ft.)
Elevation difference = 1.400(Ft.) Slope = 8.235 %
Top of Initial Area Slope adjusted by User to 7.143 %
INITIAL AREA TIME OF CONCENTRATION CALCULATIONS:
The maximum overland flow distance is 95.00 (Ft)
for the top area slope value of 7.14 %, in a development type of
24.0 DU/A or Less
In Accordance With Figure 3-3
Initial Area Time of Concentration = 3.74 minutes
TC = [1.8*( 1.1-C)*distance(Ft.)" .5)/(% slope"(1/3)]
TC = [1.8*(1.1-0.6900)*( 95.000".5)/( 7.143"(1/3)]= 3.74
Calculated TC of 3.735 minutes is less than 5 minutes,
resetting TC to 5.0 minutes for rainfall intensity calculations
Rainfall intensity (I) = 7.377(ln/Hr) for a 100.0 year storm
Effective runoff coefficient used for area (Q=KCIA) is C = 0.690
Subarea runoff = 0.153(CFS)
Total initial stream area = 0.030(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
Process from Point/Station 1.011 to Poiht/Station 2.031
**** CONFLUENCE OF MINOR STREAMS **":*
Along Main Stream number: 1 in normal stream number 2
Stream flow area = 0.030(Ac.)
Runoff from this stream = 0.153(CFS)
Time of concentration = 3.74 min.
Rainfall intensity = 7.377(ln/Hr)
Summary of stream data:
Stream Flow rate TC Rainfall Intensity
No. (CFS) (min) (ln/Hr)
1 0.341 5.79 6.708
2 0.153 3.74 7.377
Qmax(1) =
1.000 * 1.000 * 0.341)+
0.909 * 1.000 * 0.153)+= 0.480
Qmax(2) =
1.000 * 0.645 * 0.341) +
1.000 * 1.000 * 0.153) + = 0.373
Total of 2 streams to confluence:
Flow rates before confluence point:
0.341 0.153
'.: "
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Maximum flow rates at confluence using above data:
. 0.480 0.373
Area of streams before confluence:
0.070 0.030
Results of confluence:
Total flow rate = 0.480(CFS)
Time of concentration = 5.794 min.
Effective stream area after confluence = 0.1 OO(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 2.031 to Point/Station 2.032
**** PIPEFLOW TRAVEL TIME (User specified size) ****
Upstream point/station elevation = 122.220(Ft.)
Downstream point/station elevation = 121.560(Ft.)
Pipe length = 16.00(Ft.) Manning's N = 0.013
No. of pipes = 1 Required pipe flow = 0.480(CFS)
Given pipe size = 6.00(ln.)
Calculated individual pipe flow = 0.480(CFS)
Normal flow depth in pipe = 2.72(ln.)
Flow top width inside pipe = 5.97(ln.)
Critical Depth = 4.24(1n.)
Pipe flow velocity = 5.56(Ft/s)
Travel time through pipe = 0.05 min.
Time of concentration (TC) = 5.84 min.
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 2.031 to Point/Station 2.032
**** CONFLUENCE OF MINOR STREAMS ****
Along Main Stream number: 1 in normal stream number 1
Stream flow area = 0.100(Ac.)
Runoff from this stream = 0.480(CFS)
Time of concentration = 5.84 min.
Rainfall intensity = 6.673(1n/Hr)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 2.041 to Point/Station 2.042
**** INITIAL AREA EVALUATION ****
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 1.000
Decimal fraction soil group D = 0.000
[HIGH DENSITY RESIDENTIAL
(24.0 DU/A or Less )
Impervious value, Ai = 0.650
Sub-Area C Value = 0.690
Initial subarea total flow distance = 66.000(Ft.)
Highest elevation = 158.500(Ft.)
Lowest elevation = 157.200(Ft.) .
Elevation difference = 1.300(Ft.) Slope = 1.970 %
INITIAL AREA TIME OF CONCENTRATION CALCULATIONS:
The maximum overland flow distance is 75.00 (Ft)
for the top area slope value of 1.97 %, in a development type of..
24.0 DU/A or Less
In Accordance With Figure 3-3
Initial Area Time of Concentration = 5.10 minutes
TC = [1.8*(1.1-C)*distance(Ft.)'\5)/(% slope"(1/3)]
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TC = [1.8*(1.1-0.6900)*( 75.0001\.5)/( 1.9:7.01\(1/3)]= 5.10·
Rainfall intensity (I) = 7.285(ln/Hr) for a 100.0 year storm
Effective runoff coefficient used for area (Q=KCIA) is C = 0.690
Subarea runoff = 0.151 (CFS)
Total initial stream area = 0.030(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 2.042 to Point/Station 2.032
**** IRREGULAR CHANNEL FLOW TRAVEL TIME ****
Depth of flow = 0.351 (Ft.). Average velocity = 0.403(Ft/s)
******* Irregular Channel Data ***********
Information entered for subchannel number 1 :
Point number 'X' coordinate 'Y' coordinate
1 0.00 0.66
2 2.00 0.00
3 4.00 0.66
Manning's 'N' friction factor = 0.250
Sub-Channel flow = 0.151 (CFS)
flow top width = 2.130(Ft.)
, velocity= 0.403(Ft/s)
area = 0.374(Sq.Ft)
Froude number = 0.169
Upstream point elevation = 124.300(Ft.)
Downstream point elevation = 123.500(Ft.)
Flow length = 16.000(Ft.)
Travel time = 0.66 min.
Time of concentration = 5.76 min.
Depth of flow = 0.351 (Ft.)
. Average velocity = 0.403(Ft/s)
Total irregular channel flow = 0.151 (CFS)
Irregular channel normal depth above invert elev. = 0.351 (Ft.)
Average velocity of channel(s) = 0.403(Ft/s)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 2.042 to Point/Station 2.032
**** CONFLUENCE OF MINOR STREAMS ****
Along Main Stream number: 1 in normal stream number 2
Stream flow area = 0.030(Ac.)
Runoff from this stream = 0.151 (CFS)
Time of concentration = 5.76 min.
Rainfall intensity = 6.734(ln/Hr)
Summary of stream data:
Stream Flow rate TC
No. (CFS) (min)
Rainfa" Intensity
(ln/Hr)
1 0.480 5.84
2 0.151 5.76
Qmax(1) =
1.000 * 1.000 *
0.991 * 1.000 *
Qmax(2) =
1.000 * 0.986 *
1.000* 1.000*
6.673
6.734
0.480) +
0.151)+=
0.480) +
0.151)+=
0.630
0.624
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Total of 2 streams to confluence:
Flow rates before confluence point:
0.480 0.151
Maximum flow rates at confluence using above data:
0.630 0.624
Area of streams before confluence:
0.100 0.030
Results of confluence:
Total flow rate = 0.630(CFS)
Time of concentration = 5.842 min.
Effective stream area after confluence = 0.130(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 2.032 to Point/Station 2.053 >
**** PIPEFLOW TRAVEL TIME (User specified size) ****
Upstream point/station elevation = 121.560(Ft.)
Downstream pOint/station elevation = 120.330(Ft.)
Pipe length = 30.00(Ft.) Manning's N = 0.013
No. of pipes = 1 Required pipe flow = 0.630(CFS) _
,Given pipe size = 6.00(ln.)
Calculated individual pipe flow = 0.630(CFS)
Normal flow depth in pipe = 3.19(ln.)
Flow top width inside pipe = 5.99{1n.)
Critical Depth = 4.83(ln.)
Pipe flow velocity = 5.93(Ft/s)
Travel time through pipe = 0.08 min.
Time of concentration (TC) = 5.93 min.
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 2.032 to Point/Station 2.053
**** CONFLUENCE OF MINOR STREAMS ****
Along Main Stream number: 1 in normal stream number 1
Stream flow area = 0.130(Ac.)
Runoff from this stream = 0.630(CFS)
Time of concentration = 5.93 min.
Rainfall intensity = 6.611 (In/Hr)
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*++++++++++
Process from Point/Station 2.051 to Point/Station 5.052
**** INITIAL AREA EVALUATION ****
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 1.000
Decimal fraction soil group D = 0.000
[HIGH DENSITY RESIDENTIAL
(24.0 DU/A or Less )
Impervious value, Ai = 0.650
Sub-Area C Value = 0.690
Initial subarea total flow distance = 63.000(Ft.)
Highest elevation = 158.500(Ft.)
Lowest elevation = 157.200(Ft.)
Elevation difference = 1.300(Ft.) Slope = 2.063 %
INITIAL AREA TIME OF CONCENTRATION CALCULATIONS:
The maximum overland flow distance is 75.00 (Ft)
for the top area slope value of 2.06 %, in a development type of
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24.0 DU/A or Less
In Accordance With Figure 3-3
Initial Area Time of Concentration = 5.02 minutes
TC = [1.8*(1.1-C)*distance(Ft.)".5)/(% slope"(1/3)]
TC = [1.S*(1.1-0.6900)*( 75.000".5)/( 2.063"(1/3)]= 5.02
Rainfall intensity (I) = 7.35S(ln/Hr) for a 100.0 year storm
Effective runoff coefficient used for area (Q=KCIA) is C = 0.690
Subarea runoff = 0.254(CFS)
Total initial stream area = 0.050(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ '
Process from Point/Station 2.052 to Point/Station 2.053
**** IRREGULAR CHANNEL FLOW TRAVEL TIME ****
Depth of flow = 00402(Ft.), Average velocity = 0.517(Ft/s)
******* Irregular Channel Data ***********
Information entered for subchannel number 1 :
Point number 'X' coordinate 'Y' coordinate
1 0.00 0.66
2 2.00 0.00
3 4.00 0.66
Manning's 'N' friction factor = 0.250
Sub-Channel flow = 0.254(CFS)
flow top width = 20439(Ft.)
, velocity= 0.517(Ft/s)
area::: 00491 (Sq.Ft)
Froude number = 0.203
Upstream point elevation = 122 .600(Ft.)
Downstream point elevation = 121.500(Ft.)
Flow length = 16.000(Ft.)
Travel time = 0.52 min.
Time of concentration = 5.54 min.
Depth of flow = 0.402(Ft.)
Average velocity = 0.517(Ft/s)
Total irregular channel flow = 0.254(CFS)
Irregular channel normal depth above invert elev. = 00402(Ft.)
Average velocity of channel(s) = 0.517(Ft/s)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 5.052 to Point/Station 2.053
**** CONFLUENCE OF MINOR STREAMS ****
Along Main Stream number: 1 in normal stream number 2
Stream flow area = 0.050(Ac.)
Runoff from this stream = 0.254(CFS)
Time of concentration = 5.54 min.
Rainfall intensity = 6.90S(ln/Hr)
Summary of stream data:
Stream Flow rate TC
No. (CFS) (min)
1 0.630 5.93
2 0.254 5.54
Qmax(1) =
1.000 * 1.000 *
Rainfall Intensity
(In/Hr)
6.611
6.90S
0.630) +
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0.957 *
Qmax(2) =
1.000 *
1.000 *
1.000 *
0.934 *
1.000 *
0.254) + =
0.630) +
0.254) + =
Total of 2 streams to confluence:
Flow rates before confluence point:
0.630 0.254
0.873
0.842
Maximum flow rates at confluence using above data:
0.873 0.842
Area of streams before confluence:
0.130 0.050
Results of confluence:
Total flow rate = 0.873(CFS)
Time of concentration = 5.926 min.
. Effective stream area after confluence = 0 .180(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 2.053 to Point/Station 2.063
**** PIPEFLOW TRAVEL TIME (User specified size) ****
Upstream point/station elevation = 120.330(Ft.)
Downstream point/station elevation = 119.100(Ft.)
Pipe length = 30.00(Ft.) Manning's N = 0.013
No. of pipes = 1 Required pipe flow = 0.873(CFS)
Given pipe size = 6.00(ln.)
Calculated individual pipe flow = 0.873(CFS)
Normal flow depth in pipe = 3.94(ln.)
Flow top width inside pipe = 5.70(ln.)
Critical Depth = 5.48(ln.)
Pipe flow velocity = 6.38(Ft/s)
Travel time through pipe = 0.08 min.
Time of concentration (TC) = 6.00 min.
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 2.053 to Point/Station 2.063
**** CONFLUENCE OF MINOR STREAMS ****
Along Main Stream number: 1 in normal stream number 1
Stream flow area = 0.180(Ac.)
Runoff from this stream = 0.873(CFS)
Time of concentration = 6.00 min.
Rainfall intensity = 6.555(ln/Hr)
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++~++++++
Process from Point/Station 2.061 to Point/Station 2.062
**** INITIAL AREA EVALUATION ****
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 1.000
Decimal fraction soil group D = 0.000
[HIGH DENSITY RESIDENTIAL
(24.0 DU/A or Less )
Impervious value, Ai = 0.650
Sub-Area C Value = 0.690
Initial subarea total flow distance = 65.000(Ft.)
Highest elevation = 158.500(Ft.)
Lowest elevation = 157.200(Ft.)
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Elevation difference = 1.300(Ft.) Slope = 2.000 %
INITIAL AREA TIME OF CONCENTRATION CALCULATIONS:
The maximum overland flow distance is 75.00 (Ft)
for the top area slope value of 2.00 %, in a development type of
24.0 DU/A or Less
In Accordance With Figure 3-3
Initial Area Time of Concentration = 5.07 minutes
. TC = [1.8*(1.1-C)*distance(Ft.)A.5)/(% slopeA(1/3)]
TC = [1.8*(1.1-0.6900)*( 75.000A.5)/( 2.000A(1/3)]= 5.07
Rainfall intenSity (I) = 7.309(ln/Hr) for a 100.0 year storm
Effective runoff coefficient used for area (Q=KCIA) is C = 0.690
Subarea runoff = 0.252(CFS)
Total initial stream area = 0.050(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++~+
Process from Point/Station 2.062 to Point/Station 2.063
**** IRREGULAR CHANNEL FLOW TRAVEL TIME ****
Depth of flow = 0.441 (Ft.), Average velocity = 0.428(Ft/s)
******* Irregular Channel Data ***********
Information entered for subchannel number 1 :
Point number 'X' coordinate 'Y' coordinate
1 0.00 0.66
2 2.00 0.00
3 4.00 0.66
Manning's 'N' friction factor = 0.250
Sub-Channel flow = 0.252(CFS)
flow top width = 2.673(Ft.)
, velocity= 0.428(Ft/s)
area = 0.589(Sq.Ft)
Froude number = 0.161
Upstream point elevation = 122.100(Ft.)
Downstream point elevation = 120.600(Ft.)
Flow length = 36.000(Ft.)
Travel time = 1.40 min.
Time of concentration = 6.48 min.
Depth of flow = 0.441(Ft.)
Average velocity = 0.428(Ft/s)
Total irregular channel flow = '0.252(CFS)
Irregular channel normal depth above invert elev. = 0.441 (Ft.)
Average velocity of channel(s) = 0.428(Ft/s)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 2.062 to Point/Station 2.063
**** CONFLUENCE OF MINOR STREAMS ****
Along Main Stream number: 1 in normal stream number 2
Stream flow area = 0.050(Ac.)
Runoff from this stream = 0.252(CFS)
Time of concentration = 6.48 min.
Rainfall intenSity = 6.244(ln/Hr)
Summary of stream data:
Stream Flow rate TC
No. (CFS) (min)
Rainfall Intensity
(In/Hr)
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1 0.873 6.00 6.555
2 0.252 6.48 6.244
Qmax(1) =
1.000 * 1.000 * 0.873) +
1.000 * 0.927 * 0.252) += 1.106
Qmax(2) =
0.953 * 1.000 * 0.873) +
1.000 * 1.000 * 0.252) + = 1.083
Total of 2 streams to confluence:
Flow rates before confluence point:
0.873 0.252
Maximum flow rates at confluence using above data:
1.106 1.083
Area of streams before confluence:
0.180 0.050
Results of confluence:
Total flow rate = 1.106(CFS)
Time of concentration = 6.005 min.
Effective stream area after confluence = 0.230(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 2.063 to Point/Station 2.073
**** PIPEFLOW TRAVEL TIME (User specified size) ****
Upstream point/station elevation = 119.100(Ft.)
Downstream point/station elevation = 117 .870(Ft.)
Pipe length = 30.00(Ft.) Manning's N = 0.013
No. of pipes = 1 Required pipe flow = 1.106(CFS)
Given pipe size = 6.00(ln.)
Calculated individual pipe flow = 1.106(CFS)
Normal flow depth in pipe = 4.78(1n.)
Flow top width inside pipe = 4.83(1n.)
Critical depth could not be calculated.
Pipe flow velocity = 6.59(Ft/s)
Travel time through pipe = 0.08 min.
Time of concentration (TC) = 6.08 min.
++++++++++++++++++++++++++++++++++++++++++++++++++.++++++++++++++++++++
Process from Point/Station 2.063 to Point/Station 2.073
**** CONFLUENCE OF MINOR STREAMS ****
Along Main Stream number: 1 in normal stream number 1
Stream flow area = 0.230(Ac.)
Runoff from this stream = 1.106(CFS)
Time of concentration = 6.08 min.
Rainfall intensity = 6.503(ln/Hr)
++++++++++++++++++++++++++++++++++++++++++++++++++++-:1-++++++++++++,+++++
Process from Point/Station 2.071 to Point/Station 2.072
**** INITIAL AREA EVALUATION ****
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 1.000
Decimal fraction soil group D = 0.000
[HIGH DENSITY RESIDENTIAL
(24.0 DU/A or Less )
Impervious value, Ai = 0.650
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Sub-Area C Value = 0.690
Initial subarea total flow distance = 53.000(Ft.)
Highest elevation = 15B.500(Ft.)
Lowest elevation = 157 .200(Ft.)
Elevation difference = 1.300(Ft.) Slope = 2.453 %
INITIAL AREA TIME OF CONCENTRATION CALCULATIONS:
The maximum overland flow distance is 75.00 (Ft)
for the top area slope value of 2.45 %, in a development type of
24.0 DU/A or Less
In Accordance With Figure 3-3
Initial Area Time of Concentration = 4.74 minutes
TC = [1.B*(1.1-C)*distance(Ft.)".5)/(% slopel\(1/3)] .
TC = [1.B*(1.1-0.6900)*( 75.0001\.5)/( 2.4531\(1/3)]= 4.74
Calculated TC of 4.739 minutes is less than 5 minutes,
resetting TC to 5.0 minutes for rainfall intensity calculations
Rainfall intensity (I) = 7.377(ln/Hr) for a 100.0 year storm
Effective runoff coefficient used for area (Q=KCIA) is C = 0.690
Subarea runoff = 0.407(CFS)
Total initial stream area = O.OBO(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++~~+++~++++++++
Process from PoinUStation 2.072 to PoinUStation 2.073
**** IRREGULAR CHANNEL FLOW TRAVEL TIME ****
Depth of flow = 0.529(Ft.), Average velocity = O.4BO(FUs)
******* Irregular Channel Data ***********
Information entered for subchannel number 1 :
Point number 'X' coordinate 'Y' coordinate
1 0.00 0.66
2 2.00 0.00
3 4.00 0.66
Manning's 'N' friction factor = 0.250
Sub-Channel flow = 0.407(CFS)
flow top width = 3.206(Ft.)
, velocity= O.4BO(FUs)
area = 0.B4B(Sq.Ft)
Froude number = 0.165
Upstream point elevation = 119.BOO(Ft.)
Downstream point elevation = 119.100(Ft.)
Flow length = 17 .000(Ft.)
Travel time = 0.59 min.
Time of concentration = 5.33 min.
Depth of flow = 0.529(Ft.)
Average velocity = O.4BO(FUs)
Total irregular channel flow = 0.407(CFS)
Irregular channel normal depth above invert elev. = 0.S29(Ft.)
Average velocity of channel(s) = ·0.480(FUs)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
: Process from PoinUStation 2.072 to PoinUStation 2.013
**** CONFLUENCE OF MINOR STREAMS ****
Along Main Stream number: 1 in normal stream number 2
Stream flow area = O.OBO(Ac.)
Runoff from this stream = 0.407(CFS)
Time of concentration = 5.33 min.
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Rainfall intensity = 7.0BO(ln/Hr)
Summary of stream data:
Stream Flow rate TC Rainfall Intensity
No. (CFS) (min) (ln/Hr)
1 1.106 6.0B 6.503
2 00407 5.33 7.0BO
Qmax(1) =
1.000 * 1.000 * 1.106) +
0.91B * 1.000 * 00407) + = 1 ABO
Qmax(2) =
1.000 * 0.B76 * 1.106) +
1.000 * 1.000 * 00407) + = 1.377
Total of 2 streams to confluence:
Flow rates before confluence point:
1.106 00407
Maximum flow rates at confluence using above data:
1 ABO 1.377
Area of streams before confluence:
0.230 O.OBO
Results of confluence:
Total flow rate = 1ABO(CFS)
Time of concentration = 6.0B1 min.
Effective stream area after confluence = 0.310(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ ,.
· Process from Point/Station 2.073 to Point/Station 2.091
**** PIPEFLOW TRAVEL TIME (User specified size) ****
Upstream point/station elevation = 117 .B70(Ft.)
Downstream point/station elevation = 114:700(Ft.)
Pipe length = 4B.00(Ft.) Manning's N = 0.013
No. of pipes = 1 Required pipe flow = 1ABO(CFS)
Given pipe size = 6.00(ln.)
NOTE: Normal flow is pressure flow in user selected pipe size.
The approximate hydraulic grade line above the pipe invert is
1A95(Ft.) at the headworks or inlet of the pipe(s)
Pipe friction loss = 3.341 (Ft.)
Minor friction loss = 1.324(Ft.) K-factor == 1.50
Critical depth could not be calculated.
Pipe flow velocity = 7.54(Ft/s)
Travel time through pipe = 0.11 min.
Time of concentration (TC) = 6.19 min.
· ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ ..
Process from Point/Station 2.073 to Point/Station 2.091
**** CONFLUENCE OF MINOR STREAMS ****
Along Main Stream number: 1 in normal stream number 1
Stream flow area = 0.310(Ac.)
· Runoff from this stream = 1ABO(CFS)
Time of concentration = 6.19 min.
Rainfall intensity = 6A30(ln/Hr)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 2.0B1 to Point/Station 2.0B2
**** INITIAL AREA EVALUATION ****
1
1
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1
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1
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1
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1
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Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 1.000
Decimal fraction soil group D = 0.000
[HIGH DENSITY RESIDENTIAL
(24.0 DU/A or Less )
Impervious value, Ai = 0.650
Sub-Area C Value = 0.690
Initial subarea total flow distance = 50.000(Ft.)
Highest elevation = 158.500(Ft.)
Lowest elevation = 157 .200(Ft.)
Elevation difference = 1.300(Ft.) Slope = 2.600 %
INITIAL AREA TIME OF CONCENTRATION CALCULATIONS:
The maximum overland flow distance is 90.00 (Ft)
. for the top area slope value of 2.60 %, in a development type of
24.0 DU/A or Less
In Accordance With Figure 3-3
Initial Area Time of Concentration = 5.09 minutes
TC = [1.8*( 1.1-C)*distance(Ft.)A.5)/(% slopel\( 1 /3)]
TC = [1.8*(1.1-0.6900)*( 90.0001\.5)/( 2.6001\(1/3)]= 5.09
Rainfall intensity (I) = 7.291 (In/Hr) for a 100.0 year storm
Effective runoff coefficient used for area (Q=KCIA) is C = 0.690
Subarea runoff = 0.402(CFS)
Total initial stream area = 0.080(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 2.082 to Point/Station 2.091
**** IRREGULAR CHANNEL FLOW TRAVEL TIME ****
Depth of flow = 0.480(Ft.), Average velocity = 0.577(Ft/s)
******* Irregular Channel Data ***********
Information entered for subchannel number 1 :
Point number 'X' coordinate 'Y' coordinate
1 0.00 0.66
2 2.00 0.00
3 4.00 0.66
Manning's 'N' friction factor = 0.250
Sub-Channel flow = 0.402(CFS)
flow top width = 2.908(Ft.)
, velocity= 0.577(Ft/s)
area = 0.698(Sq.Ft)
Froude number = 0.207
Upstream point elevation = 118.300(Ft.)
Downstream point elevation = 116.000(Ft.)
Flow length = 34.000(Ft.)
Travel time = 0.98 min.
Time of concentration = 6.07 min.
Depth of flow = 0.480(Ft.)
Average velocity = 0.577(Ft/s)
Total irregular channel flow = 0.402(CFS)
Irregular channel normal depth above invert elev. = 0.480(Ft.)
Average velocity of channel(s) = 0.577(Ft/s)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 2.082 to Point/Station 2.091
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I
I
I
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I
**** CONFLUENCE OF MINOR STREAMS ****
Along Main Stream number: 1 in normal stream number 2
Stream flow area = 0.080(Ac.)
Runoff from this stream = 0.402(CFS)
Time of concentration = 6.07 min.
Rainfall intensity = 6.507(ln/Hr)
Summary of stream data:
. Stream Flow rate TC Rainfall Intensity
No. (CFS) (min) (In/Hr)
1 1.480 6.19 6.430
2 0.402 6.07 6.507
Qmax(1) =
1.000 * 1.000 * 1.480) +
0.988 * 1.000 * 0.402) + = 1.878
Qmax(2) =
1.000 * 0.982 * 1.480) +
1.000 * 1.000 * 0.402) + = 1.856
Total of 2 streams to confluence:
Flow rates before confluence point:
1.480 0.402
Maximum flow rates at confluence using above data:
1.878 1.856
Area of streams before confluence:
0.310 0.080
Results of confluence:
Total flow rate = 1.878(CFS)
Time of concentration = 6.187 min.
Effective stream area after confluence = 0.390(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 2.091 to Point/Station 2.092
**** IRREGULAR CHANNEL FLOW TRAVEL TIME ****
Estimated mean flow rate at midpoint of channel = 1.926(CFS)
Depth offlow = 0.944(Ft.), Average velocity = 0.532(Ft/s)
******* Irregular Channel Data ***********
Information entered for subchannel number 1 :
Point number 'X' coordinate 'Y' coordinate
1 0.00 1.00
2 3.00 0.00
3 4.00 0.00
4 7.00 1.00
Manning's 'N' friction factor = 0.250
Sub-Channel flow = 1.926(CFS}
flow top width = 6.665(Ft.)
, velocity= 0.532(Ft/s)
area = 3.619(Sq.Ft)
Froude number = 0.127
Upstream pOint elevation = 116.000(Ft.)
Downstream point elevation = 114.000(Ft.)
Flow length = 104.000(Ft.)
Travel time = 3.26 min.
1
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Time of concentration = 9.44 min.
Depth of flow = 0.944(Ft.)
Average velocity = 0.532(Ft/s)
Total irregular channel flow = 1.926(CFS)
Irregular channel normal depth above invert elev. = 0.944(Ft.)
Average velocity of channel(s) = 0.532(Ft/s)
Adding area flow to channel
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 1.000
Decimal fraction soil group D = 0.000
[HIGH DENSITY RESIDENTIAL
(24.0 DU/A or Less )
Impervious value, Ai = 0.650
Sub-Area C Value = 0.690
The area added to the existing stream causes a
a lower flow rate of Q = 1.588(CFS}
therefore the upstream flow rate of Q = 1.878(CFS} is being used
Rainfall intensity = 4.896(ln/Hr) for a 100.0 year storm
Effective runoff coefficient used for total area
(Q=KCIA) is C = 0.690 CA = 0.324
Subarea runoff = O.OOO(CFS) for 0.080(Ac.)
Total runoff = 1.878(CFS) Total area = 0.470(Ac.)
Depth of flow = 0.934(Ft.}, Average velocity = 0.529(Ft/s).
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 2.092 to Point/Station 2.093
**** PIPEFLOW TRAVEL TIME (User specified size) ****
Upstream point/station elevation = 113.000(Ft.)
Downstream point/station elevation = 112.000(Ft.)
Pipe length = 23.00(Ft.} Manning's N = 0.013
No. of pipes = 1 Required pipe flow = 1.878(CFS)
Given pipe size = 8.00(ln.)
Calculated individual pipe flow = 1.878(CFS)
Normal flow depth in pipe = 5.14(1n.}
Flow top width inside pipe = 7.67(ln.)
Critical Depth = 7.41 (I n.)
Pipe flow velocity = 7.91 (Ft/s)
Travel time through pipe = 0.05 min.
Time of concentration (TC) = 9.49 min.
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 2.093 to Point/Station 2.112
**** IRREGULAR CHANNEL FLOW TRAVEL TIME ****
Depth of flow = 0.075(Ft.), Average velocity = 8.349(Ft/s)
******* Irregular Channel Data *********** -
Information entered for subchannel number 1 :
Point number 'X' coordinate 'Y' coordinate
1 0.00 0.25
2 0.00 0.00
3 3.00 0.00
4 3.00 0.25
Manning's 'N' friction factor = 0.016
Sub-Channel flow = 1.878(CFS}
flow top width = 3.000(Ft.}
-.".
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1
I
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, velocity= 8.349(Ft/s)
area = 0.225(Sq.Ft)
Froude number = 5.373
Upstream point elevation = 112.000(Ft.)
Downstream point elevation = 109.000(Ft.)
Flow length = 11.000(Ft.)
Travel time = 0.02 min.
Time of concentration = 9.51 min.
Depth of flow = 0.075(Ft.)
Average velocity = 8.349(Ft/s)
Total irregular channel flow = 1.878(CFS)
Irregular channel normal depth above invert elev. = 0.075(Ft.)
Average velocity of channel(s) = 8.349(Ft/s)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 2.093 to Point/Station 2.112
**** CONFLUENCE OF MINOR STREAMS ****
Along Main Stream number: 1 in normal stream number 1
Stream flow area = 0.470(Ac.)
Runoff from this stream = 1.878(CFS)
Time of concentration = 9.51 min.
Rainfall intensity = 4.872(ln/Hr)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++~+++++++*+++++.
Process from Point/Station 2.111 to Point/Station 2.111
**** USER DEFINED FLOW INFORMATION AT A POINT ****
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 1.000
Decimal fraction soil group D = 0.000
[HIGH DENSITY RESIDENTIAL
(24.0 DU/A or Less )
Impervious value, Ai = 0.650
Sub-Area C Value = 0.690
Rainfall intensity (I) = 4.200(ln/Hr) for a 100.0 year storm
User specified values are as follows:
TC = 11.97 min. Rain intensity = 4.20(ln/Hr)
Total area = 0.988(Ac.) Total runoff = 3.179(CFS)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 2.111 to Point/Station 2.112
**** IRREGULAR CHANNEL FLOW TRAVEL TIME ****
Estimated mean flow rate at midpoint of channel = 3.369(CFS)
Depth of flow = 0.296(Ft.), Average velocity = 5.169(Ft/s)
******* Irregular Channel Data ***********
Information entered for subchannel number 1 :
Point number 'X' coordinate 'Y' coordinate
1 0.00 0.90
2 31.00 0.14
3 31.65 0.00
4 31.75 0.50
Manning's 'N' friction factor = 0.016
Sub-Channel flow = 3.369(CFS)
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I
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flow top width = 7.072(Ft.)
I velocity= 5.169(Ft/s)
area = 0.652(Sq.Ft)
Froude number = 3.000
Upstream point elevation = 125.000(Ft.)
Downstream point elevation = 109. 000(Ft.)
Flow length = 205.000(Ft.)
Travel time = 0.66 min.
Time of concentration = 12.63 min.
Depth of flow = 0 .296(Ft.)
Average velocity = 5.169(Ftls)
Total irregular channel flow = 3.369(CFS)
Irregular channel normal depth above invert elev. = 0.296(Ft.)
Average velocity of channel(s) = 5.169(Ft/s)
Adding area flow to channel
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 1.000
Decimal fraction soil group D = 0.000
[HIGH DENSITY RESIDENTIAL
(24.0 DU/A or Less )
Impervious value, Ai = 0.650
Sub-Area C Value = 0.690
Rainfall intensity = 4.057(1n/Hr) for a 100.0 year storm
Effective runoff coefficient used for total area
(Q=KCIA) is C = 0.690 CA = 0.861
Subarea runoff = 0.315(CFS) for 0.260(Ac.)
Total runoff = 3.494(CFS) Total area = 1.248(Ac.)
Depth of flow = 0.299(Ft.), Average velocity = 5.214(Ftls}
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++'+++
Process from PointiStation 2.111 to Point/Station 2.112
**** CONFLUENCE OF MINOR STREAMS ****
Along Main Stream number: 1 in normal stream number 2
Stream flow area = 1.248(Ac.)
Runoff from this stream = 3.494(CFS)
Time of concentration = 12.63 min.
Rainfall intensity = 4.057(ln/Hr)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Process from Point/Station 2.101 to PointiStation 2.112
**** INITIAL AREA EVALUATION ****
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 1.000
Decimal fraction soil group D = 0.000
[HIGH DENSITY RESIDENTIAL
(24.0 DU/A or Less )
Impervious value, Ai = 0.650
Sub-Area C Value = 0.690
Initial subarea total flow distance = 66.000(Ft.)
Highest elevation = 126.000(Ft.)
Lowest elevation = 109.000(Ft.)
Elevation difference = 17.000(Ft.) Slope = 25.758 %
INITIAL AREA TIME OF CONCENTRATION CALCULATIONS:
The maximum overland flow distance is 100.00 (Ft)
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for the top area slope value of 25.76 %, in a development type of
24.0 DU/A or Less
In Accordance With Figure 3-3
Initial Area Time of Concentration = 2.50 minutes
TC = [1.8*(1.1-C)*distance(Ft.)".5)/(% slope"(113)]
TC = [1.8*(1.1-0.6900)*( 100.000".5)/( 25.758"(1/3)]= 2.50
Calculated TC of 2.499 minutes is less than 5 minutes,
resetting TC to 5.0 minutes for rainfall intensity calculations
Rainfall intensity (I) = 7.377(1n/Hr) for a 100.0 year storm
Effective runoff coefficient used for area (Q=KCIA) is C = 0.690
Subarea runoff = 0.153(CFS) .
Total initial stream area = 0.030(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ .
Process from Point/Station 2.101 to Point/Station 2.112
**** CONFLUENCE OF MINOR STREAMS ****
Along Main Stream number: 1 in normal stream number 3
Stream flow area = 0.030(Ac.)
Runoff from this stream = 0.153(CFS)
Time of concentration = 2.50 min.
Rainfall intensity = 7.377(ln/Hr)
Summary of stream data:
Stream Flow rate TC Rainfall Intensity
No. (CFS) (min) (In/Hr)
1 1.878 9.51 4.872
2 3.494 12.63 4.057
3 0.153 2.50 7.377
Qmax(1) =
1.000 * 1.000 * 1.878) +
1.000 * 0.753 * 3.494) +
0.660 * 1.000 * 0.153) + = 4.610
Qmax(2) =
0.833 * 1.000 * 1.878) +
1.000 * 1.000 * 3.494) +
0.550 * 1.000 * 0.153) + = 5.142
Qmax(3) =
1.000 * 0.263 * 1.878) +
1.000 * 0.198 * 3.494) +
1.000 * 1.000 .. * 0.153) + = 1.337
Total of 3 streams to confluence:
Flow rates before confluence point:
1.878 3.494 0.153
Maximum flow rates at confluence using above data:
4.610 5.142 1.337
Area of streams before confluence:
0.470 1.248 0.030
Results of confluence:
Total flow rate = 5.142(CFS)
Time of concentration = 12.634 min.
Effective stream area after confluence =
End of computations, total study area =
1.748(Ac.)
1.748 (Ac.)
; .. ,' . ,~ '. '-
.~-----------.--
EXIST. OFFSllE FLOWS
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LEGEND
• • • • • • • • • • • • •• BASIN BOUNDARY
('?2:r0l11-::::J+-~._--BASIN DESIGNATION I--lO~.l1;::·1 O:;;';.~iI-~+-... :.~-:--=--=--=--=--=~:~t~~ALlTY
RUNOFF (CFS)
_---~---~-----DIRECTION OF FLOW
----------------PROPOSED SWALE
~C~Pj#~3~@~t:::===CONCENTRA TION POINT 19. 0.14 CFS WATER QUALITY RUNOFF
I I
r>2S2<)(J
IMPERVIOUS AREA
AREA TREAlED BY THE BIO-SWALE
PL I
1!!.. c----; PROPOSED ..-----1-PLANTING PER
LANDSCAPE PLANS
NATIVE
MAlERIAL
3:1 MAX
SLOPE
BIO-SWALE ' A' DETAIL
NTS
N
10 5 0 10 20 30
~i ~~~~~I~~I
SCALE IN FEET
GRAPHIC SCALE
DATE: May 06. 09 10:31am by.dmasson
FILE: I: \DWG\00\0040\Repor!s \SWMP\0040-SWMP-40B-409.dwg
"A"
MAS SON & ASS 0 C I ATE S, INC .
PLANNING ~ ENGINEERING ~ SURVEYING
200 E. WASHINGTON AVE.'" SUITE 200.,. ESCONDIDO.,. CA 92025-1816
TEL (760) 741-3570'" FAX (760) 741-1786.,. www.masson-Ossoc.com
WATER MANAGEMENT PLAN -LOT 408,409
LA COSTA CANYON HOMES
CT 08-02 I PUD 08-02 I HOP 08-02
DA'IB
1-
,
\
>
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10
j
LEGEND
~2y5J 0.09 0:37
Ig: ~~.1 CFS I
•••••••••••
--------
----;). - - -----?> - ----
'P
N
BASIN NUMBER
BASIN AREA (AC.)
CONCENTRA 1l0N POINT
100-YEAR FLOW
BASIN BOUNDARY
PROPERTY LINE
FLOW LINE
5~0~~~10_~_210~~~31°
SCALE IN FEET
GRAPHIC SCALE
DATE: May 06, 09 10: 330m by: dmasson
FILE: I: \DWG\OO\0040\Reporls \Hydrology\0040-Posl-Dev-408-409.dwg [ii, MAS SON & ASS 0 C I ATE S, INC.
PLANNING,. ENGINEERING" SURVEYING
j' 200 E. WASHINGTON AVE.'" SUITE 200'1' ESCONDIDO ... CA 92025-1816
r TEL (760) 741-3570'1' FAX (760) 741-1786 T www.mosson-assoc.com
PN 0040 DAre 09-V-Q8
\
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LEGEND
[2·f5 J 0.09 om
Ig: ~~.1 CFS I
•••••••••••
--------
-----'» - - ------'» - ----
BASIN NUMBER
BASIN AREA (AC.)
CONCENTRATION POINT
100-YEAR FLOW
BASIN BOUNDARY
PROPERTY LINE
FLOW LINE
10 5 0 10 20 30 ~I ~~~S~CA~LE~I~N ;;F;;EE;;T ;;I~~~I
GRAPHIC SCALE
DATE: May 06, 09 10:34am by.dmasson .
FILE: I: \DWG\00\0040\Reports\Hydrology\0040-Pre-Dev-40B-409.dwg [i] MAS SON & ASS 0 C I ATE S, INC.
PLANNING T ENGINEERING T SURVEYING
200 E. WASHINGTON AVE.' SUITE 200. ESCONDIDO. CA 92025-1816
TEL (760) 741-3570 ... FAX (760) 741-1786.,. www.mosson-assoc.com
-RISn-"B" ~PR~E-DEVELOPMENT HYDROLOGY MAP -LOT 408, 409
LA COSTA CANYON HOMES
CT 08-02 I PUD 08-02 I HOP 08-02
PNOO4O