HomeMy WebLinkAboutCT 02-04; La Costa Oaks Sourth Neighborhood 3.14; Storm Water Management Plan; 2002-08-18HUNSAKER
^ASSOCIATES
SAN DIEGO,
PLANNING
ENGINEERING
SURVEYING
IRVINE
LOS ANGELES
RIVERSIDE
SAN DIEGO
N C.
ADDENDUM TO STORM WATER
MANAGEMENT PLAN
for
LA COSTA OAKS SOUTH
NEIGHBORHOODS 3.14
City of Carlsbad, California
Prepared for:
Real Estate Collateral Management Company
c/o Morrow Development
1903 Wright Place, Suite 180
Carlsbad, CA 92008
W.O. 2352-39
August 18, 2003
DAVE HAMMAR
LEX WILLIMAN
ALISA VIALPANDO
10179 Huennekens St.
San Diego, CA 92121
(858) 558-4500 PH
(858) 558-1414 FX
www.HunsakerSD.com
lnfo@HunsakerSD.com
Eric Mosolgo, R.C.E.
Water Resources Department Manager
Hunsaker & Associates San Diego, Inc.
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La Costa Oaks South (Neighborhood 3.14)
Addendum to Storm Water Management Plan
TABLE OF CONTENTS
CHAPTER 1 - Executive Summary
1.1 Introduction
1.2 Summary of Pre-Developed Conditions
1.3 Summary of Proposed Development
1.4 Results and Recommendations
CHAPTER 2 - Storm Water Criteria
2.1 Regional Water Quality Control Board Criteria
2.2 City of Carlsbad SUSMP Criteria
CHAPTER 3 - Identification of Typical Pollutants
3.1 Anticipated Pollutants from Project Site
3.2 Sediment
3.3 Nutrients
3.4 Trash & Debris
3.5 Oxygen-Demanding Substances
3.6 Oil & Grease
CHAPTER 4 - Conditions of Concern
4.1 Receiving Watershed Descriptions
4.2 Pollutants of Concem in Receiving Watersheds
4.3 Peak Flow Attenuation (Regional Detention Facility)
CHAPTER 5 - Volume-Based Best Management Practices (BMPs)
5.1 Design Criteria
5.2 Extended Detention Basins
5.3 Pollutant Removal
5.4 Maintenance Requirements
CHAPTER 6 - Flow-Based BMPs
6.1 Design Criteria
6.2 Vortechs Treatment Units
6.3 Pollutant Removal Efficiency Table
6.4 Maintenance Requirements
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La Costa Oaks South (Neighborhood 3.14)
Addendum to Storm Water Management Plan
CHAPTER 7 - Source Control BMPs
7.1 Landscaping
7.2 Urban Housekeeping
7.3 Automobile Use
CHAPTER 8 - Site BMP Design (Extended Detention Basin)
8.1 BMP Location
8.2 Determination of Treatment Volume
8.3 Water Quality Basin Design
CHAPTER 9 - Site BMP Design (Vortechs Treatment Units)
9.1 BMP Locations
9.2 Determination of Treatment Flows
9.3 Vortechs Treatment Unit Selections
CHAPTER 10 - References
List of Tables and Figures
Chapter 1 - Watershed Map
Chapter 1 - BMP Location Map
Chapter 3 - Pollutant Category Table
Chapter 4 - San Diego Region Hydrologic Divisions
Chapter 4 - Combined 1998 and Draft 2002 Section 303(d) Update
Chapter 4 - Beneficial Uses of Inland Surface Waters
Chapter 4 - Water Quality Objectives
Chapter 5 - Pollutant Removal Efficiency Table (Volume-Based BMPs)
Chapter 6 - Pollutant Removal Efficiency Table (Flow-Based BMPs)
Chapter 8 - Extended Detention Basin Location Map
Chapter 8 - Water Quality Basin Schematic (Profile)
Chapter 8 - Stage-Storage Data
Chapter 8 - Stage-Discharge Data for Water Quality Basin Dewatering
Chapter 8 - 85*^ Percentile Rainfall Isopluvial Map
Chapter 9 - Neighborhood 3.9 West BMP Location Map
Chapter 9 - Neighborhood 3.9 East BMP Location Map
Chapter 9 - Neighborhood 3.12 BMP Location Map
Chapter 9 - Neighborhood 3.15 BMP Location Map
Chapter 9 - Design Runoff Determination Summary Table
Chapter 9 - Vortechs Unit Treatment Capacity Table
Chapter 9 - Vortechs System Data
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La Costa Oaks South (Neighborhood 3.14)
Addendum to Storm Water Management Plan
CHAPTER 1 - EXECUTIVE SUMMARY
This report is an addendum to the "Storm Water Management Plan for La Costa
Oaks South", specifically addressing treatment of 85*^ percentile mnoff from
Neighborhood 3.14. All runoff from Neighborhood 3.14 drain to the regional water
quality basin located at the downstream end of Neighborhood 3.12 (see Watershed
Map on the following page).
Per the "Hydrology Study for La Costa Oaks Neighborhoods 3.14", dated
January 6, 2003, the storm drain systems from Neighborhood 3.14 had the following
total combined drainage parameters upon their discharge to the public storm drain
system.
Neiqhboriiood 3.14
Drainage Area = 40.5 acres
Developed Area = 32.5 acres
Impervious Area = 9 acres
85*^ Percentile Runoff Volume = 0.30 acre-feet
As shown in the ensuing text from the "Storm Water Management Plan for La Costa
Oaks South", the water quality basin at the downstream end of Neighborhood 3.12
has a treatment capacity of 3.0 acre-feet. The combined 85* percentile runoff
volume from Neighborhood 3.14 is equal to 0.36 acre-feet, which is less than the
3.0 acre-feet of treatment storage provided in the water quality basin downstream.
85'^ percentile design runoff calculations are provided in Chapter 8 of this report.
Since the downstream treatment facility is a volume-based BMP, hydrograph
methods were used to determine the corresponding 85*^ percentile mnoff volume
from Neighborhood 3.14
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La Costa Oaks South (Neighborhood 3.14)
Addendum to Storm Water Management Plan
1.1 - Introduction
The La Costa Oaks South development is located east of the existing alignment of
Rancho Santa Fe Road, north of the existing extension of La Costa Avenue, and
south of the Stanley Mahr Reservoir in the City of Carlsbad, California (see
Watershed Map on the following page). Neighborhoods 3.08 through 3.15 comprise
the Oaks South portion of the larger La Costa Oaks development.
Per the City of Carlsbad SUSMP, the La Costa Oaks South project is classified as a
Priority Project and subject to the City's Permanent Storm Water BMP Requirements.
This Storm Water Management Plan (SWMP) has been prepared pursuant to
requirements set forth in the City of Carlsbad's "Standard Urban Storm Water
Mitigation Plan (SUSMP)." All calculations are consistent with criteria set forth by
the Regional Water Quality Control Board's Order No. 2001-01, and the City of
Carlsbad SUSMP.
This SWMP recommends the location and sizing of site Best Management Practices
(BMPs) which include one water quality extended detention basin and four Vortechs
treatment units (see BMP Location Map in this chapter).
Furthermore, this report determines anticipated project pollutants, pollutants of
concern in the receiving watershed, peak flow mitigation, recommended source
control BMPs, and methodology used for the design of flow-based and volume-
based BMPs.
1.2 - Summary of Pre-Developed Conditions
As shown in the watershed map on the following page, the majority of the pre-
developed La Costa Oaks South site drained to the Encinitas Creek watershed. The
remainder of the site (portions of Neighborhoods 3.08 and 3.09) drained to the San
Marcos Creek watershed via an existing inlet to the old Rancho Santa Fe storm
drain system.
The Regional Water Quality Control Board has identified both Encinitas Creek and
San Marcos Creek as part of the Carlsbad Hydrologic Unit, San Marcos Hydrologic
Area, and the Batiquitos Hydrologic Subarea (basin number 4.51).
1.3 - Summarv of Proposed Development
Development of the La Costa Oaks South site will include the constmction of single-
family homes as well as the associated streets, sidewalks, landscaping and utilities.
As part of the development, a regional detention basin was constructed at the
downstream end of the project in Neighborhood 3.12.
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""^eTrWATERSHED^"
< ENCINITAS^^^^g
;jf ^WATERSHfelS^
HYDROLOGY MAP FOR
lA COSTA OAKS SOUTH
CITY OF CARLSBAD. CALIFORNIA
35"
Wl"
SCALE l'>3a0'
/VORTECH i
UNIT
^VORTECH
) ' UNIT m
LEGEND
WATERSHED BOUNDARY
BASIN WATERSHED BOUNDARY
NBGHBCRHOOD BOUNDARY
AREA
WATER QUAUTY DEVICE
HUNSAKER
Si ASSOCIATES
IAN ailf* !•«
BMP LOCATION MAP FOR
LA COSTA OAKS SOUTH
CITY OF CARLSBAD, CALIFORNIA
SHEET
1
OF
1
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La Costa Oaks South (Neighborhood 3.14)
Addendum to Storm Water Management Plan
The "Addendum to Preliminary Hydrology Study for Villages of La Costa - The
Ridge & The Oaks", prepared by Hunsaker & Associates and dated
October 23, 2001, details the design of the regional detention facility.
As shown in the referenced report, the regional detention facility mitigates design
peak flow increases below pre-development levels. In addition to peak flow
attenuation, this basin also serves as a regional water quality basin.
A riser extends from the basin bottom elevation of 285 feet to a top elevation of 293
feet. Storm water treatment occurs in this bottom 8 feet of the basin while peak flow
attenuation is provided in the basin above elevation 293 feet.
Four flow-based BMPs will be located at other site discharge locations. 85*^
percentile runoff will be treated in the proposed Vortechs systems at Paseo
Conifera, Neighborhood 3.09, Avenida Junipero, and La Costa Avenue prior to
discharging into the receiving drainage system.
1.4 - Results and Recommendations
The water quality / regional detention facility is located at the downstream (south)
end of Neighborhood 3.12 (see BMP Location Map on the following page). Runoff
from Neighborhoods 3.08, 3.10, 3.11, 3.12, 3.13, 3.14 and 3.15 drains to this
location. Additionally, runoff from a large offsite area will also drain to the basin area.
The combined watershed area draining the basin was determined to be 401 acres.
Using the 85**^ percentile rainfall of 0.68 inches (see Isopluvial Map at the end of this
chapter) and assuming 20 percent imperviousness in the contributing watershed,
HEC-HMS calculations predicted an 85*^ percentile runoff volume of roughly 3.0
acre-feet.
The basin's stage-storage data shows that the water quality basin area has a peak
storage volume of 3.0 acre-feet at the riser top elevation of 293 feet. The total basin
storage volume for detention (above elevation 293 feet) is 7.6 acre-feet. Since the
basin storage volume in the water quality portion of the basin equals the projected
85* percentile runoff volume, the BMP meets SUSMP criteria.
Each of the proposed Vortechs units is an offline precast treatment unit. The 85"^
percentile design flow rate is forced into the treatment area by a diversion weir built
in the upstream junction. Flows in excess of the design flow rate pass over the weir
and proceed downstream.
Vortechs Model 1000 units, with a treatment flow capacity of 1.6 cfs, are
recommended for the treatment units at Neighborhood 3.09, La Costa Avenue and
Avenida Junipero while a Model 2000 is recommended at Paseo Conifera.
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BASIN WATERSHED BOUNDARY
NEIGHBORHOOD BOUNDARY
AREA
WATER QUALITY DEVICE 9
HUNSAKER
& ASSOCIATES
tAtk •laaa mc
wmttmrntrnttttrnm
BMP LOCATION MAP FOR
LA COSTA OAKS SOUTH
NEIGHBORHOOD 3.14
CITY OF CARLSBAD, CALIFORNIA
SHEET
1
OF
1
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La Costa Oaks South (Neighborhood 3.14)
Addendum to Storm Water Management Plan
CHAPTER 2 - STORM WATER CRITERIA
2.1 - Regional Water Qualitv Control Board Criteria
All runoff conveyed in the proposed storm drain systems will be treated in
compliance with Regional Water Quality Control Board regulations and NPDES
criteria prior to discharging to natural watercourses. California Regional Water
Quality Control Board Order No. 2001-01, dated February 21, 2001, sets waste
discharge requirements for discharges of urban runoff from municipal storm
separate drainage systems draining the watersheds of San Diego County.
Per the RWQCB Order, post-development runoff from a site shall not contain
pollutant loads which cause or contribute to an exceedance of receiving water
quality objectives or which have not been reduced to the maximum extent
practicable. Post-construction Best Management Practices (BMPs), which refer to
specific storm water management techniques that are applied to manage
construction and post-construction site mnoff and minimize erosion, include source
control - aimed at reducing the amount of sediment and other pollutants - and
treatment controls that keep soil and other pollutants onsite once they have been
loosened by storm water erosion.
Post construction pollutants are a result of the urban development of the property
and the effects of automobile use. Runoff from paved surfaces can contain both
sediment (in the form of silt and sand) as well as a variety of pollutants transported
by the sediment. Landscape activities by homeowners are an additional source of
sediment.
All structural BMPs shall be located to infiltrate, filter, or treat the required runoff
volume or flow (based on the 85"^ percentile rainfall) prior to its discharge to any
receiving watercourse supporting beneficial uses.
2.2 - Citv of Carlsbad SUSMP Criteria
Per the City of Carisbad SUSMP, the La Costa Oaks South project is classified as a
Priority Project and subject to the City's Pennanent Storm Water BMP
Requirements. These requirements required the preparation of this Storm Water
Management Plan.
The Storm Water Applicability Checklist, which must be included along with Grading
Plan applications, is included on the following page.
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storm Water Standards
4/03/03
APPENDIX A
STORM WATER REQUIREMENTS APPUCABILITY CHECKLIST
Complete Sections 1 and 2 of the following checklist to detennine your project's
pennanent and constmction stonn water best management practices requirements.
This fonn must be completed and submitted with your permit application.
Section 1. Permanent Storm Water BMP Requirements:
If any answers to Part A are answered Tes," your project is subject to the "Priority
Project Permanent Stonn Water BMP Requirements," and "Standard Pennanent Stonn
Water BMP Requirements" in Section III, "Pennanent Storm Water BMP Selection
Procedure" in the Storm Water Standards manual.
If all answers to Part A are "No," and any answers to Part B are "Yes," your project is
only subject to the "Standard Pennanent Stonn Water BMP Requirements". If every
question in Part A and B is answered "No," your project is exempt ft-om pennanent
stonn water requirements.
Part A: Determine Priority Project Permanent Storm Water BMP Requirements.
Does the project meet the definition of one or more of the priority project
categories?* Yes No
1. Detached residential development of 10 or more units /
2. Attached residential development of 10 or more units
3. Commercial development greater than 100,000 square feet • 4. Automotive repair shop /
5. Restaurant
6. Steep hillside development greater than 5,000 square feet
7. Proiect discharaing to receiving waters within Environmentally Sensitive /Vreas
8. Parking lots greater than or equal to 5,000 ft' or with at least 15 parking spaces, and
potentially exposed to urban runoff /
9. Streets, roads, highways, and freeways which would create a new paved surface that is
5,000 square feet or greater /
* Refer to the definitions section in the Stonn Water Standards for expanded definitions of the priority
proiect categories.
Limited Exclusion: Trenching and resur^cing work associated with utility projects are not considered
priority projects. Paridng lots, buildings and other structures associated with utility projects are
priority projects if one or more of the criteria in Part A is met. If all answers to Part A are "No",
continue to Part B.
30
La Costa Oaks South (Neighborhood 3.14)
Addendum to Storm Water IVianagement Plan
CHAPTER 3 - IDENTIFICATION OF TYPICAL POLLUTANTS
3.1 - Anticipated Pollutants from Project Site
The following table details typical anticipated and potential pollutants generated by
various land use types. The La Costa Oaks South development will consist of
detached single-family residences. Thus, the Detached Residential Development
category has been highlighted to cleariy illustrate which general pollutant categories
are anticipated from the project area.
General Pollutant Categories
Priority
Project
Categories Sediments Nutrients Heavy IVIetais Organic Compounds Trash & Debris Oxygen Demanding Substances Oil & Grease Bacteria & Viruses Pesticides Detached
Residential
Development
X X X X X X X
Attached
Residential
Development
X x X p(i) p(2) P X
Commercial
Development
>100,000 ft^
p(1) p(i) p(2) X p{5) X p(3) p(5)
Automotive
Repair
Shops
x X(4)(5) X X
Restaurants X X X X
Hillside
Development
>5,000 ft^
X x X X X X
Parking Lots p(1) p(1) X X p(1) X p{1)
Streets,
Highways &
Freeways
X p(1) X X(4) X p(5) X
Retail Gas
Outlets X X(4) X X
X = anticipated
P = potential
(1) A potential pollutant if landscaping exists on-site.
(2) A potential pollutant if the project includes uncovered parking areas.
(3) A potential pollutant if land use involves food or animal waste products.
(4) Including petroleum hydrocarbons.
(5) Including solvents.
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La Costa Oaks South (Neighborhood 3.14)
Addendum to Storm Water Management Plan
3.2 - Sediment
Soils or other surface materials eroded and then transported or deposited by the
action of wind, water, ice, or gravity. Sediments can increase turbidity, clog fish gills,
reduce spawning habitat, smother bottom dwelling organisms, and suppress aquatic
vegetative growth.
3.3 - Nutrients
Inorganic substances, such as nitrogen and phosphorous, that commonly exist in the
form of mineral salts that are either dissolved or suspended in water. Primary
sources of nutrients in urtDan runoff are fertilizers and eroded soils. Excessive
discharge of nutrients to water bodies and streams can cause excessive aquatic
algae and plant growth. Such excessive production, referred to as cultural
eutrophication, may lead to excessive decay of organic matter in the water body,
loss of oxygen in the water, release of toxins in sediment, and the eventual death of
aquatic organisms.
3.4 - Trash & Debris
Examples include paper, plastic, leaves, grass cuttings, and food waste, which may
have a significant impact on the recreational value of a water body and aquatic
habitat. Excess organic matter can create a high biochemical oxygen demand in a
stream and thereby lower its water quality. In areas where stagnant water is present,
the presence of excess organic matter can promote septic conditions resulting in the
growth of undesirable organisms and the release of odorous and hazardous
compounds such as hydrogen sulfide.
3.5 - Oxvaen-Demandina Substances
Biodegradable organic material as well as chemicals that react with dissolved
oxygen in water to form other compounds. Compounds such as ammonia and
hydrogen sulfide are examples of oxygen-demanding compounds. The oxygen
demand of a substance can lead to depletion of dissolved oxygen in a water body
and possibly the development of septic conditions.
3.6 - Oil & Grease
Characterized as high high-molecular weight organic compounds. Primary sources
of oil and grease are petroleum hydrocarbon products, motor products from leaking
vehicles, oils, waxes, and high-molecular weight fatty acids. Elevated oil and grease
content can decrease the aesthetic value of the water body, as well as the water
quality.
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IV
La Costa Oaks South (Neighborhood 3.14)
Addendum to Storm Water Management Plan
CHAPTER 4 - CONDITIONS OF CONCERN
4.1 - Receiving Watershied Descriptions
As shown in the watershed map on the following page, the majority of the pre-
developed La Costa Oaks South site drained to the Encinitas Creek watershed. In
developed conditions, runoff from a 401-acre watershed drains through the regional
detention facility near La Costa Avenue (in Neighborhood 3.12) and then discharges
to a tributary of Encinitas Creek.
Runoff from Neighborhood 3.09 discharges to a storm drain system constructed
along with the new alignment of Rancho Santa Fe Road. This runoff, along with
mnoff from Rancho Santa Fe Road confluences with the aforementioned 401-acre
watershed around the location of the La Costa Avenue - Camino De Los Coches
intersection.
At the southeast corner of the Oaks South site, a 5-acre watershed discharges to a
side canyon near Avenida Junipero (in the headwater regions of Encinitas Creek). In
developed conditions, the total drainage area from the site area (including offsite
areas draining through the site) to the Encinitas Creek watershed is roughly 422
acres.
Portions of Neighborhood 3.08 drain to the San Marcos Creek watershed via an
existing inlet to the old Rancho Santa Fe stonn drain system. In developed
conditions, the developed condition drainage area from the site area to the San
Marcos Creek watershed is roughly 24 acres.
The Regional Water Quality Control Board has identified both Encinitas Creek and
San Marcos Creek as part of the Carisbad Hydrologic Unit, San Marcos Hydrologic
Area, and the Batiquitos Hydrologic Subarea (basin number 4.51).
4.2 - Pollutants of Concern in Receiving Watersheds
Neither Encinitas Creek nor San Marcos Creek are listed on the EPA's 303(d) List of
endangered waterways (included in this Chapter). Per the "Water Quality Plan for
the San Diego Basin", the beneficial uses for both waterways include agricultural
supply, contact water recreation, non-contact recreation, warm freshwater habitat,
and wildlife habitat.
Table 3-2 from the "Water Quality Plan for the San Diego Basin" (included at the end
of this Chapter) lists water quality objectives for a variety of potential pollutants
required to sustain the beneficial uses of the San Marcos hydrologic area.
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La Costa Oaks South (Neighborhood 3.14)
Addendum to Storm Water Management Plan
4.3 - Peak Flow Attenuation (Regional Detention Facility)
The "Addendum to Preliminary Hydrology Study for Villages of La Costa - The
Ridge & The Oaks", prepared by Hunsaker & Associates and dated October 23,
2001, details the design of the regional detention facility located near La Costa
Avenue in Neighborhood 3.12.
As shown in the referenced report, the regional detention facility mitigates design
peak flow increases below pre-development levels. In addition to peak flow
attenuation, this basin also serves as a regional water quality basin.
A riser extends from the basin bottom elevation of 285 feet to a top elevation of 293
feet. Storm water treatment occurs in this bottom 8 feet of the basin while peak flow
attenuation is provided in the basin above elevation 293 feet.
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TABLE 1
SAN DIEGO REGION HYDROLOGIC DIVISIONS
1/2/01
BASIN
NUMBER HYDROLOGIC BASIM BASIN
NUMBER HYDROLOGIC BASIN
1.00
1.10
1.11
1.12
1.13
1.14
1.20
1.21
1.22
1.2a
1.24
1.25
1.26
1.27
1.28
1.30
1J1
1.32
1,40
UO
1.51
1.52
1.S3
2.00 2.10
2.11 2.12
2.13 2.20
2.21
2.22
2.23
2.30 2.31
2.32 2J3
2.34
2J5
2.36
2.40
2.41
2.42 2.43
2.44 2.50
2.51
2.52
2.80
2.61 2.62
2.63 2.70
2.71 2.72
2.73
SAN JUAN HYDROLOGIC UNIT
Laguna HA
San Joaquin Hills HSA
Lagtsia Beach HSA
Aliso HSA
Oana Point HSA
Mission Viejo HA
Oso HSA Upper Trabuco HSA
Middle Ttabuco HSA
GobainadGra HSA
Upper San Juan HSA
Middle San Jtan HSA
Lower San Juan HSA
Ortega HSA
SanQementa HA
Prima Deshecha HSA
Segunda Desiiecha HSA
San Mateo Canyon HA
SanOnofre HA San Onoflra Valley HSA
Las Pulgas HSA
Stuart HSA
SANTA MARGARrrA HYDROLOGIC UNH"
Ysidora
Lower Ysidora
Ctieppo
Upper Ysidora
DeLuz
DeLuz Creek Gavitan
Vallecitos
Munrieta
Wlldomar
Murrteta
French
Lower Oomenigani Domenlgonl
Diamond Auld
Bachelor Mountain
Gertnidls
Lower Tucalota
Tucalota
Pauba
Wolf
Wilson
Lancaster Valley
Lewis
iteed Valley
Cave Rocks
Lower Coahuita
Upper Coalttiila
Araa
HA
HSA
HSA
HSA
HA
HSA
HSA
HSA
HA
HSA
HSA
HSA
HSA
HSA
HSA
HA
HSA
HSA
HSA
HSA
HA
HSA
HSA
HA
HSA
HSA
HSA
HA
HSA
HSA
HSA
• 2J*
2.80
2.81
Z.B2
2.83
2.84
2.90
2.91
2.92
2.93
Z94
3.00
3.10
3.11
3.12
3.13
3.14
3.15
3.16
3.20
3.21
3.22
3.23
3J0
3.31
X32
4.00
4.10
4.20
4.21
4.22
4J0
4.31
4.32
4.40 rrsr
1 4.51 HisT-
- 4.53
4.60
4.61
4.62
4.63
5.00
5.10
5.11
5.12
5.20
5.21
5.22
5.23
5.24
Buns. HSA
Aguanga HA
Vail HSA-Devils Hole HSA
Redec HSA
TUIeCreeIc HSA
Oakgrove HA •
LowM'Culp HSA
Pravitt Canyon HSA
Dodge HSA
Chihuahua HSA
SAN LUIS REY HYDROLOGIC UNO" Lower San Luis HA
Mission HSA
BonsaO HSA -'
Moosa HSA.
Valley Center .HSA
woods HSA
RIncon HSA
Monserata .HA'
Pala . H^A
Pauma HSA
La Jolla Amago • HSA
Wttner Valley HA
Warner ..' HSA
Combs HSA
CARLSBAD HYDROLOGIC UNHT
Loma Alta
Buena Vista Creek
BSalto
Vista
Agua Hedionda
LosMonos
Buena
Encinas "SanT I Marcos
Riehlaiid
1\MinOaks
Escondido Creek San EIIJo
Escondido LakeWOhlltord
HA
HA
HSA
HSA
HA
HSA
HSA
HA TW-
HSA HSA
HA
HSA
HSA
HSA
SAN OlEGUrrO HYDROLOGIC UNn* Solana Beach
Rancho Santa Fe
La Jolla
Hodges
Del Dios Green
Felidta
Bear
HA
HSA
HSA
HA
HSA HSA
HSA
HSA
T-1-1
I
I
I
i
I
I
I
Hy*.";^.!"°"ft ^OO^ Section 303(d) Update
Descriptor Waterbody
21 Loma Alta HA
(904.10) Pacific Ocean Shoreline
^ (904^10^ ^ LomaAlta Slough
Segment / Area ^
at Loma Alta Creek Mouth
23 Buena Vista Creek
HA (904.20) Pacific Ocean Shoreline
24 El Salto HSA
(904.21)
25 Los Monos HSA
(904.31)
at Buena Vista Creek
Carlsbad City Beach at Carlsbad
Village Drive
Carlsbad State Beach at Pine
Avenue
I' ' ^0 Los Monos HSA
i (904.31)
27 San Marcos HA
[ (904.50)
Buena Vista Lagoon
Agua Hedionda Lagoon
Agua Hedionda Creek lower portion
Pacific Ocean Shoreline at Moonlight State Beach
^» Escondido Creek _
HA (904.60) Pacific Ocean Shoreline I I »-> <^out.QUI
29 San Elijo HSA
(904.61)
I
.V, San Dieguito HU
I (905.00)
Del Dios HSA
(905.21)
Del Dios HSA
(905.21)
at San Eiiio Lagoon
at Solana Beach
San Elijo Lagoon
I
, 33 Felicita HSA
(905.23)
Felicita HSA
(905.23)
135 Highland HSA
(905.31)
|36 Sutheriand HSA
(905.53)
Pa^i- ou .. at San Dieguito Lagoon MoutT
Pacific Ocean Shoreline I orrey Pines State Beach at Del
Mar (Anderson Canyon)
Green Valley Creek
Hodges Reservoir Entire Reservoir
Felicita Creek
Kit Carson Creek
Cloverdale Creek
Sutheriand Reservoir Entire Reservoir
I
I
lastupdatwl7/22/20Q3
SAVTOS\303dlhftSD Stair Report.20Oa20(a draft 303d M
hMp:/W.swrcb.ca.gov/h«qcb9*rog,am.003dli«frabl,4-C^^^
Pollutant /
Stressor
Bacterial
Indicators^
Bacterial
Indicators^
Eutrophic
-Bacterial
Indicators^
Extent of Year
Impairment ° LIsfaH
1 mile
8 acres
0.65 miles
Bacterial
Indicators^ 350 acres
Sedimentation /
Siltation seres
Nutrients
Bacterial
Indicators^
150 acres
5 acres
Sedimentation /
Siltation
°!azinon lower 2 miles
Total Dissolved
Solids
Bacterial
Indicators^
_ iacteria
Indicators^
Bacterial
Indicators^
0.4 miles
0.8 miles
150 acres
Eutrophic 330 acres
Sulfate
Color
Nitrogen
Phosphorus
Total Dissolved
Solids
Total Dissolved
Solids
Total Dissolved
Solids
Phosphorus
1 mile
Entire
Reservoir
Total Dissolved
Solids
1 mile
1 mile
Color Entire
Reservoir
1998
1998
"iggT
1998
1998
1998
1998
^2002"
lower 8 miles 2002
Sedimentation /
Siltation 150 acres
-Bacterial 0-8 miles
Indicators^
1998
"Tiir
1998
1998
2002
2002
lower 2 miles 2002
2002
looF
2002
Table 2-2. BENEFICIAL USES OF INLAND SURFACE WATERS
BENEFICIAL USE
Inland Surface Waters "^'^ Hydrologic M A 1 P G F P R R B W C W R S
Unit Basin U G N R W R O E E 1 A O 1 A P
Number N R D O R S W C C O R L L R W
C H 1 2 L M D D E N
San Diego County Coastal Streams -'Continued
Buena Vista Lagoon 4.21 See Coastal Waters-Table 2-3
Buena Vista Creek 4.22 + • • • •
Buena Vista Creek 4.21 + • • • • • •
Agua Hedionda 4.31 See Coastal Waters- Table 2-3
Agua Hedionda Creek 4.32 • • • • • • •
Buena Creek 4.32 • • • • • • •
Agua Hedionda Creek 4.31 • • • -. • • • •
Letterbox canyon 4.31 • • • • • • •
Canyon de las Encinas 4.40 + 0 • • •
San Marcos Creek Watershed
Batiquitos Lagoon 4.51 See Coastal Waters- Table 2-3
San Marcos Creek 4.52 + • • • • • •
unnamed Intermittent streams 4.53 + • • • •
San Marcos Creek Watershed
^jSan Marcos Creek 4.51 + • • • • •
y/^jEncinitas Creek 4.51 r
+ • -• • • -•
• Existing Beneficial Use
O Potential Beneficial Use
+ Excepted From MUN (See Text)
1 Watertjodies are listed multiple times if they cross hydrologic area or sub area boundaries.
Beneficial use designations apply to all tributaries to tiie indicated waterbody. if not listed separately.
Table 2-2
BENEFICIAL USES 2-27 Septembers, 19S4
J
m
Table 3-2. WATER QUALITY OBJECTIVES
Concentrations not to be exceeded more ttian 10% of Uie time during any one one year period.
Consfa'tiuent (mg/L or as noted)
Inland Surface Waters Hydrologic
Unit Basin
Number TDS CI SO, %Na 1 N&P Fe Mn MBAS B ODOR Turb
NTU
Color
Units F
SAN LUIS REY HYDROLOGIC UNIT 903.00
Lower San Luis HA 3.10 500 250 250 60 a 0.3 0.05 0.5 0.75 none 20 20 1.0
Monserat HA 3.20 500 250 250 60 a 0.3 0.05 0.5 0.75 none 20 20 1.0 1
Warner Valley HA 3.30 500 250 250 60 a 0.3 0.05 0.5 0.75 none 20 20 1.0 1
CARLSBAD HYDROLOGIC UNIT^ 904.00
Loma Alta HA 4.10 none 20 20 1.0 II
Buena Vista Creek HA 4.20 500 250 250 60 a 0.3 0.05 0.5 0.75 none 20 20 1.0
Agua Hedionda HA 4.30 500 250 250 60 - a 0.3 0.05 0.5 0.75 none 20 20 1.0
Encinas HA 4.40 none 20 20 1.0 1 ^an Marcos HA> 4.50 500 250 250 60 a 0.3 0.05 0.5 0.75 none 20 20 1.0J
Escondido Creek HA 4.60 500 250 250 60 a 0.3 0.05 0.5 0.75 none 20 20 1.0 1
SAN DIEGUITO HYDROLOGIC UNIT 905.00
Solana Beach HA 5.10 500 250 250 60 a 0.3 0.05 0.5 0.75 none 20 20 1.0
Hodges HA 5.20 500 250 250 60 a 0.3 0.05 0.5 0.75 none 20 20 1.0 1
San Pasqual HA 5.30 500 250 250 60 a 0.3 0.05 0.5 0.75 none 20 20 1.0 1
Santa Maria Valley HA 5.40 500 250 250 60 a 0.3 0.05 0.5 0.75 none 20 20 1.0 II
Santa Ysabel HA 5.50 500 250 250-60 . a 0.3 0.05 0.5 0.75 none 20 20 1.0 II
PENASQUITOS HYDROLOGIC UNIT 906.00
Miramar Reservoir HA 6.10 500 250 250 60 a :p.3 0.05 0.5 0.75 none 20 20 1.0 1
Poway HA 6.20 500 250 250 60 a 0.3 0.05 0.5 0.75 none 20 20 1.0 1
HSA - Hydrologic Sub Area (Lower case letters Indicate endnotes foUowing the table.)
Table 3-2
WATER QUALITY OBJECTIVES Page 3-23 Septembers, 199^
V
La Costa Oaks South (Neighborhood 3.14)
Addendum to Storm Water Management Plan
CHAPTER 5 - VOLUME-BASED BMPS
5.1 - Design Criteria
Volume-based BMPs shall be designed to mitigate the volume of runoff produced
from a 24-hour 85* percentile storni event, as determined from the local historical
rainfall record. The 85^ percentile rainfall for the La Costa Oaks site is 0.68 inches
(see figure in Chapter 7).
Such facilities are usually designed to store the first flush runoff event below the
principle spillway elevation (riser, weir, etc.) while providing a means for low flow
dewatering. Outlet structures will be designed to convey runoff from the 100-year
frequency storm to the basin.
5.2 - Extended Detention Basin
The La Costa Oaks South site contains one volume-based BMP - the bottom portion
of the regional detention facility that operates as an extended duration storm water
quality basin. This basin will collect the first flush runoff volume and retain it in the
basin for a period of 24-48 hours.
85* percentile runoff volume, contained below the overflow elevation of the basin
riser, will be slowly discharged from the treatment control basin via low flow orifices
in the basin riser. After passing through the riser, an outlet pipe will dewater the
basin and discharge runoff to the natural drainage course downstream.
Runoff in excess of the first flush runoff volume will bypass the basin via a large
diameter riser opening (top elevation = 293 feet).
5.3 - Pollutant Removal
As shown in the table (from the City of Carisbad SUSMP) on the following page,
extended detention basins provide the following treatment efficiencies:
Sediment- High removal efficiency
Nutrients - Medium removal efficiency
Heavy Metals - Medium removal efficiency
Trash & Debris - High removal efficiency
Oxygen-Demanding Substances - Medium removal efficiency
Oil & Grease - Medium removal efficiency
5.4 - l\/laintenance Requirements
Proper maintenance is required to insure optimum performance of the basins.
General BMP inspections should check for structural integrity of the riser, debris and
litter removai to prevent blockage of outiet orifices, etc. Fencing should be provided
at the top of the basins to serve as protection to the public from the safety hazards
inherent with standing water in the basin.
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W.O. 2352-39 8/20/03 10:50 AM
storm Water Standards
4/03/03
Table 4. Structural Treatment Control BIWP Selection Matrbc.
Pollutant of Concem Treatment Control BMP Categories
Biofiiters Detention
Basins
infiltration
Basinsli)
Wet Ponds or
Wetlands
Drainage
inserts
Filtration Hydrodynamic
Seoarator SvsfemsP) Sediment M H H H L H M Nutrients L M 1^ M L M L
Heavy Metals M M H L H L
Organic Compounds U U U U . L M L Trash & Debris L H U U M H M Oxygen Demanding
Substances L M M M L M L
Bacteria U U H U L • M L Oil & Grease M 1^ U U L H L
Pesticides U U U U L U L
(2) Also known as iiydrodynamic devices and baffle boxes.
L: Low removal efficiency
M: Medium removai efiidency
H: High removal effidency
U: Unknown removal effidency
Sources: Guidance Specifying Management Measures for Sources ofNonpoint Polluthn in Coastal Waters (1993) National
Stormwater Best Management Practices Database (2001). and Guide for BMP Selection In Urban [)eveioped Areas {2QQ]).
La Costa Oaks South (Neighborliood 3.14)
Addendum to Storm Water Management Plan
Maintenance of the extended detention basin will be the responsibility of the
Homeowners Association until the time at which the City of Carisbad assumes
maintenance responsibilities. For proper maintenance to be performed, the storm
water treatment facility must be accessible to both maintenance personnel and their
equipment and materials.
Factors that affect the operational performance of a volume-based extended
detention ponds include mowing, control of pond vegetation, removal of
accumulated bottom sediments, removal of debris from all inflow and outflow
stmctures, unclogging of orifice perforations, etc. Periodic inspections should be
perfomied following each significant storm. These basins should be inspected at
least twice a year to evaluate facility operation.
Periodic inspections of both Water Quality Basins should be perfomied at regular
intervals throughout the year. Additional inspections will be required after major
rainfall events (defined per this Maintenance Plan as 24-hour rainfall events in
excess of 1 inch).
During the periodic and post-major event rainfall inspections, the inspector must
identify any repairs and maintenance activities deemed necessary, including the
removal of trash, debris, and sediment from the upper chamber of the basin area.
All riser orifices should be unclogged during the periodic and post-rainfall
inspections.
A Registered Civil Engineer will conduct an annual inspection of each basin. This
inspection will include a thorough inspection of the basin area, outlet structure and
internal gabion structure. The engineer will identify any required repairs as well as
corrective maintenance activity required to maintain the hydraulic performance of the
basins. Annual maintenance activities will include the removal of the heavy
vegetation that will inevitably grow in the basin. Roughly Vi half of the vegetation
should be removed from the basin at each annual maintenance session, including all
woody or aquatic vegetation and other obstructions to flow. Ail sediment, trash, and
debris should be removed from the upper and lower chambers of the basin at the
annual maintenance session.
Sediment removed during periodic, post-major rainfall event, and annual
maintenance can be placed in a sanitary landfill or used for composting activities. If
no basin maintenance takes places for a period of longer than 1 year, then trapped
pollutants may be deemed hazardous and special requirements may apply to
disposal activities. In such a case, removals would require testing prior to disposal in
a sanitary landfill.
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W.O. 2352-39 8/20/03 10:50 AM
VI
La Costa Oaks South (Neighborhood 3.14)
Addendum to Storm Water Management Plan
CHAPTER 6 - FLOW-BASED BMPS
6.1 - Design Criteria
Flow-based BMPs shall be designed to mitigate the maximum flowrate of runoff
produced from a rainfall intensity of 0.2 inch per hour. Such basins utilize either
mechanical devices (such as vaults that produce vort:ex effects) or non-mechanical
devices (based on weir hydraulics and specially designed filters) to promote settling
and removal of pollutants from the njnoff.
Per the request of the City of Carisbad, 85* percentile flow calculations were
performed using the Rational Method. The basic Rational Method mnoff procedure
is as follows:
Design flow (Q) = C * 1* A
Runoff Coefficient I - In accordance with the County of San Diego standards, the
weighted runoff coefficient for all the areas draining to the treatment unit was
determined using the areas analyzed in the final engineering hydrology report:. The
runoff coefficient is based on the following characteristics of the watershed:
- Land Use - Single Family Residential in Developed Areas
- Soil Type - Hydrologic soil group D was assumed for all areas. Group D
soils have very slow infiltration rates when thoroughly wetted. Consisting
chiefly of clay soils with a high swelling potential, soils with a high
permanent water table, soils with clay pan or clay layer at or near the
suri'ace, and shallow soils over nearly impervious materials. Group D soils
have a very slow rate of water transmission.
Rainfall Intensity (I) - Regional Water Quality Control Board regulations and NPDES
criteria have established that flow-based BMPs shall be designed to mitigate a
rainfall intensity of 0.2 inch per hour.
Watershed Area (A) - Corresponds to total area draining to treatment unit.
6.2 - Vortechs Treatment Units
The Vortiechs Storm Water Treatment System is designed to efficiently remove grit,
contaminated sediments, metals, hydrocarbons and floating contaminants from
surface runoff. Combining swiri-concentrator and flow-control technologies to
eliminate turbulence within the system, the Vortechs System ensures the effective
capture of sediment and oils and prevents resuspension of trapped pollutants for
flows up to 25 cfs.
EM:smm h:\sw quallty\2352\39\3.14.doc
W.O. 2352-39 8/20/03 10:50 AM
La Costa Oaks South (Neighborhood 3.14)
Addendum to Storm Water Management Plan
Other features of the Vortechs Systems include the following:
Large capacity system provides an 80 percent net annual Total
Suspended Solids (TSS) removai rate
- Unit is installed below grade
Low pump-out volume and one-point access reduce maintenance costs
- Design prevents oils and other floatables from escaping the system during
cleanout
- Enhanced removal efficiencies of nutrients and heavy metals with offiine
configuration
The tangential inlet to the system creates a swiriing motion that directs settleable
solids into a pile towards the center of the grit chamber. Sediment is caught in the
swiriing flow path and settles back onto the pile after the storm event is over.
Floatable entrapment is achieved by sizing the low flow control to create a rise in the
water level of the vault that is sufficient to just submerge the inlet pipe with the 85*^
percentile flow.
6.3 - Pollutant Removai Efficiency Table
Pollutant of Concern BMP Categories
Hydrodynamic
Separation
Devices'^'
Vorlechs'^
Stormwater
Treatment System
Sediment M-H H
Nutrients L-M L-M
Heavy Metals L-M L-M
Organic Compounds L-M L-M
Trash & Debris M-H H
Oxygen Demanding Substances L L
Bacteria L L
Oil & Grease L-H H
Pesticides L L
(1) The County will periodically assess the performance characteristics of these BMPs to
update this table.
(2) Proprietary Structural BMPs. Not all serve the same function.
L (Low): Low removal efficiency (roughly 0-25%)
M (Medium): Medium removal efficiency (roughly 25-75%)
H (High): High removal efficiency (roughly 75-100%)
U: Unknown removal efficiency, applicant must provide evidence supporting use
Sources: Guidance Specifying Management Measures for Sources ofNonpoint Pollution in
Coastal Waters (1993), National Stormwater Best Management Practices Database (2001),
and Guide for BMP Selection in Urban Developed Areas (2001).
EM:smm h:\sw quality\2352\39\3.14.cloc
W.O. 2352-39 8/20/03 10:50 AM
La Costa Oaks South (Neighborhood 3.14)
Addendum to Storm Water Management Plan
6.4 - l\/laintenance Requirements
Flow-based stomn water treatment devices should be inspected periodically to
assure their condition to treat anticipated runoff. Maintenance of the proposed
Vortechnics units includes inspection and maintenance 1 to 4 times per year.
Maintenance of the Vortechs units involves the use of a "vactor tmck", which clears
the grit chamber of the treatment unit by vacuuming all the grit, oil and grease, and
water from the sump. Typically a 3-man crew is required to perform the
maintenance of the treatment unit. Property maintained Vortechs Systems will only
require evacuation of the grit chamber portion of the system. In some cases, it may
be necessary to pump out all chambers. In the event of cleaning other chambers, it
is imperative that the grit chamber be drained first.
Proper inspection includes a visual observation to ascertain whether the unit is
functioning property and measuring the amount of deposition in the unit. Floatables
should be removed and sumps cleaned when the sump storage exceeds 85 percent
of capacity specifically, or when the sediment depth has accumulated within 6 inches
of the dry-weather water level. The rate at which the system collects pollutants will
depend more heavily on site activities than the size of the unit.
EM:smm h:\sw quality\2352\39\3.14.doc
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Vii
La Costa Oaks South (Neighborhood 3.14)
Addendum to Storm Water Management Plan
CHAPTER 7 - SOURCE CONTROL BMPS
7.1 - Landscaping
Manufactured slopes shall be landscaped with suitable ground cover or installed with
an erosion control system. Homeowners should be educated as to the proper routine
maintenance to landscaped areas including trimming, pmning, weeding, mowing,
replacement or substitution of vegetation in ornamental and required landscapes.
Per the RWQCB Order, the following landscaping activities are deemed unlawful
and are thus prohibited:
- Discharges of sediment
- Discharges of pet waste
Discharges of vegetative clippings
Discharges of other landscaping or constmction-related wastes.
7.2 - Urban Houselceepinq
Fertilizer applied by homeowners, in addition to organic matter such as leaves and
lawn clippings, all result in nutrients in storm water runoff. Consumer use of
excessive herbicide or pesticide contributes toxic chemicals to runoff. Homeowners
should be educated as to the proper application of fertilizers and herbicides to lawns
and gardens.
The average household contains a wide variety of toxins such as oil/grease,
antifreeze, paint, household cleaners and solvents. Homeowners should be
educated as to the proper use, storage, and disposal of these potential storni water
runoff contaminants.
Per the RWQCB Order, the following housekeeping activities are deemed unlawful
and are thus prohibited:
Discharges of wash water from the cleaning or hosing of impervious surfaces
including parking lots, streets, sidewalks, driveways, patios, plazas, and
outdoor eating and drinking areas (landscape irrigation and lawn watering, as
well as non-commercial washing of vehicles in residential zones, is exempt
from this restriction)
- Discharges of pool or fountain water containing chloride, biocides, or other
chemicals
- Discharges or runoff" from material storage areas containing chemicals,
fuels, grease, oil, or other hazardous materials
- Discharges of food-related wastes (grease, food processing, trash bin
wash water, etc.).
EM:smm h:\sw quality\2352\39\3.14.doc
W.O. 2352-39 8/20/03 10:50 AM
La Costa Oaks South (Neighborhood 3.14)
Addendum to Storm Water Management Plan
7.3 - Automobile Use
Urban pollutants resulting from automobile use include oil, grease, antifreeze,
hydraulic fluids, copper from brakes, and various fuels. Homeowners should be
educated as to the proper use, storage, and disposal of these potential stonn water
contaminants.
Per the RWQCB Order, the following automobile use activities are deemed unlawful
and are thus prohibited:
- Discharges of wash water from the hosing or cleaning of gas stations,
auto repair garages, or other types of automotive service facilities.
- Discharges resulting from the cleaning, repair, or maintenance of any type
of equipment, machinery, or facility including motor vehicles, cement-
related equipment, port-a-potty servicing, etc.
- Discharges of wash water from mobile operations such as mobile
automobile washing, steam cleaning, power washing, and carpet cleaning.
The Homeowners Association should make all homeowners aware of the
aforementioned RWQCB regulations through a homeowners' education program. A
monitoring program should also be implemented to insure compliance.
EM:smm h:\sw quality\2352\39\3.14.doc
W.O. 2352-39 8/20/03 10:50 AM
Vill
La Costa Oaks South (Neighborhood 3.14)
Addendum to Storm Water Management Plan
CHAPTER 8 - SITE BMP DESIGN
EXTENDED DETENTION BASIN
8.1 - BMP Location
The water quality / regional detention facility is located at the downstream (south)
end of Neighborhood 3.12 (see BMP Location Map on the following page). Runoff
from Neighboriioods 3.08, 3.10, 3.11, 3.12, 3.13, 3.14 and 3.15 drains to this
location. Additionally, runoff from a large offsite area will also drain to the basin area.
The combined watershed area draining the basin was determined to be 401 acres.
8.2 - Determination of Treatment Volume
Per the "Addendum to Preliminary Hydrology Study for Villages of La Costa - The
Ridge and The Oaks (dated October 23, 2001)," HEC-HMS output shows the
drainage area to the regional detention / water quality basin is 401 acres. The
corresponding time of concentration (from a previous Rational Method analysis
contained within the "Preliminary Hydrology Study for Villages of La Costa - The
Ridge and The Oaks" is 22.3 minutes.
Using the 85*^ percentile rainfall of 0.68 inches (see Isopluvial Map at the end of this
chapter) and assuming 20 percent imperviousness in the contributing watershed,
HEC-HMS calculations predicted an 85**^ percentile runoff volume of roughly 3.0
acre-feet.
8.3 - Water Quality Basin Design
The water quality / detention basin exhibit included in this chapter shows that the
riser makes this basin double as a detention and water quality basin. The riser will
extend from the basin bottom elevation of 285 feet to a top elevation of 293 feet.
Detention basin stage-storage calculations (included in this chapter) show that no
storage effects were considered below the riser top elevation of 293 feet. In other
words, peak flow attenuation was attained in the basin storage area above the Water
Quality Basin (above elevation 293 feet)
The stage-storage data shows that the water quality basin area has a peak storage
volume of 2.97 acre-feet at the riser top elevation of 293 feet. The total basin storage
volume for detention (above elevation 293 feet) is 7.65 acre-feet.
Stage-discharge data for the riser dewatering (included in this chapter) shows that
the peak outflow from the water quality basin area is 9 cfs at elevation 293 feet. At
lower elevations in the Water Quality Basin, the corresponding outflow is less (for
instance, the discharge rate at elevation 288 feet is 2.4 cfs).
EM:smrn h:\sw quality\2352\39\3.14.doc
W.O. 2352-39 8/20/03 10:50 AM
ATTRIBUTING AREA = 401 AC
WATER QUALITY
& DETENTION
BASIN
5^
LEGEND
WATERSHED BOUNDARY
BASIN WATERSHED BOUNDARY
NEIGHBORHOOD BOUNDARY
SCALE l'=40'
BMP LOCATION MAP FOB
WATER QUALITY
BASIN
CARLSBAO, CAUFORMA
SHEET I
1
HUNSAKER & ASSOCIATES
SAN DIEGO, INC.
PROJECT: L.C, OAjiS
DES.BY: THVL/
CHECKED BY:
DATE: ^/o/
VILLAGES OF LA COSTA
STAGE- STORAGE DATA
DETENTION BASIN AT NODE 106
without a water quality component
285.0 0.00 0.00 0.00
286.0 0.23 0.12 0.12
287.0 0.35 0.29 0.41
288.0 0.38 0.36 0.77
289.0 0.40 0.39 1.16
290.0 0.43 0.42 1.58
291.0 0.45 0.44 2.02
292.0 0.48 0.47 2.48
293.0 0.50 0.49 2.97
294.0 0.53 0.51 3.49
295.0 0.55 0.54 4.03
296.0 0.69 0.62 4.65
297.0 0.82 0.75 5.40
298.0 0.94 0.88 6.28
299.0 1.02 0.98 726
300.0 1.10 1.06 8.32
301.0 1.16 1.13 9.44
302.0 1.21 1.18 10.63
with a water quality component
liili
285.0 0.00 0.00 0.00
286.0 0.23 0.12 0.12
287.0 0J5 0.29 0.41
288.0 0.38 0.36 0.77
289.0 0.40 0.39 1.16'
290.0 0.43 0.42 1.58
291.0 0.45 0.44 2.02
292.0 0.48 0.47 2.48
293.0 0.50 0.49 2.97 for stormwater quality
293.0 0.50 0.00 0.00
293.5 0.51 0.25 0.25.
294.0 0.53 0.51 0.51
295.0 0.55 0.54 1.05
296.0 0.69 0.62 1.67
297.0 0.82 0.75 2.42
298.0 0.94 0.88 3.30
299.0 1.02 0.98 4.28
300.0 1.10 1.06 5.34
301.0 1.16 1.13 6.47
302.0 1.21 1.18 7.65 for detention
I
a**
Ji-iSaB;.-!.
VILLAGES OF LA COSTA - THE OAKS
HYDRAULIC ANALYSIS OF RISER SLOTS AT NODE 106
Orifice Equation (for h > M):
tO.S Q= Ca(2gh)''"' (Equation 4-10. Kings Handbook)
Q = Ca(64.32h)'"'; C « 0.6 from Table 4-4. Kings Handbook
Q = 4.812 a(h)°where a s area of orifice opening, h = head (ft) above centeriine of opening.
Weir Fonnula (for h < M):
Q= CLH*-'' (Equation 5-10. Kings Handboolc)
C= 3.2 from Rg. 5-3
V
7.07 sq. ft.. L s 9.42 ft. @ elevation 293.0 ft. (top of riser). 285.0 ft. (floor of basin)
For Riser where:
d = 36 in., a =
and slots where:
L = 0.5 in., Ms: 6.0 in.. at 18.80 in. on center,
Then area = 0.021 sq.ft., and # of slots per row = 6.0
h t
H
i
•
ELEV.
(feet)
ROW1 ROW 2 ROWS ROW 4 ROWS ROW 6 ROW 7 TOTAL ELEV.
(feet) H(ft) Q(cfs) H(ft) Q(cfs) H(ft) Q (cfs) H(ft) Q(cfs) H(ft) Q(cfs) H(ft) Q(cfs) H(ft) Q(cfs) Q (cfs)
0.0
0.6
266.00 1.00 0.60 0.00 0.0 — — —— —-—— —— — — 0.6
266.50 1.50 0.67 0.50 0.57 —_ — — — — — — — — 1.2
287.00 2.00 0.80 1.00 0.60 0.00 0.0 1.4
287.50 2.50 0.90 1.50 0.67 0.50 0.57 — — — — — • — — — 2.1
288.00 3.00 1.00 2.00 0.80 1.00 0.60 0.00 0.0 — — -—-— — 2.4
288.50 3.50 1.09 2.50 0.90 1.50 0.67 0.50 0.57 3.2
289.00 4.00 1.17 3.00 1.00 2.00 0.80 1,00 0.60 0.00 0.0 —' — — — 3.6
289.50 4.50 1.24 3.50 1.09 2.50 0.90 1.50 0.67 0.50 0.57 — — — — 4.5
290.00 5.00 1.31 4.00 1.17. 3.00 1.00 2,00 0.80 1.00 0.60 0.00 0.0 — — 4.9
290.50 5.50 1.38 4.50 1.24 3.50 1.09 2.50 0.90 1.50 0.67 0.50 0.57 — — 5.9
291,00 6.00 1.45 5.00 1.31 4.00 1.17 3.00 1.00 2.00 0.80 1.00 0.60 0.00 0.0 6.3
291.50 6.50 1.51 5.50 1.38 4.50 1.24 3.50 1.09 2.50 0.90 1.50 0.67 0.50 0.57 7.4
292.00 7.00 1.57 6.00 1.45 5.00 1.31 4.00 1.17 3.00 1.00 2.00 0.80 1.00 0.60 7.9
292.50 7.50 1.62 6.50 1.51 5.50 1.38 4.50 1.24 3.50 1.09 2.50 0.90 1.50 0.67 8.4
293.00 8.00 1.68 7.00 1.57 6.00 1.45 5.00 1.31 4.00 1.17 3.00 1.00 2.00 0.80 g.o
slot 8/14/2001
ENCINITAS
La Costa Oaks South 3.14 - Storm Water Quality Facility Sizing
RUNOFF HYDROGRAPH (SBUH METHOD - 6-Hour Storm Event)
Given: Area = 29.3 acres
Pt 0.68 inches (Total rainfall for an 85tti percentile - 24 hour storm event)
dt 10.0 min.
Tc = 10.0 min. (Developed site conditions)
% IMP = 25%
PERVIOUS Parcel IMPERVIOUS Parcel
Area = 22.0 acres Area = 7.3 acres
CN 68 CN = 98 (assuming dry antecedent moisture condition)
S 4.71 S 0.20
0.2S = 0.94 0.2S = 0.04
Compute: Developed Conditions Runoff hydrograph
Column (3) = Rainfall Distribution for San Diego County
Column (4) = Col. (3) x Pt = 85th percentile - 6 Hour Hyetograph at this location.
Column (5) = Accumulated Sum of Col. (4)
Column (6) = [If P <= 0.2S] = 0; use PERVIOUS Area"S" value. [If P > 0.2S] = (Col.(5) - 0.2S)^/(Col.(5) + 0.8S); use PERVIOUS AreaS" value.
Column (7) = Col.(6) of present time step - Col.(6) of previous time step
Column (8) = Same method as for Col.(6), except use the IMPERVIOUS Area "S" value.
Column (9) = Col.(8) of the present time step - Col.(8) of the previous time step.
Column (10) = ((PERVIOUS area / Total area) x Col.(7)) + ((IMPERVIOUS area / Total area) x Col.(9))
Column (11) = (60.5 x Col.(IO) x Total Area) /10 (dt = 10 minutes); Routing Constant, w = dt / (2Tc + dt) =0.3333
Column (12) = Col.(12) of previous time step + (w x (Col.(11) of previous time step + Col.(11) of present time step - (2 x Col.(12) of previous time step)])
(1)
Time
Increment
"T"
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
(2)
Time
mm.
—W
20
30
40
50
60
70
80
90
100
110
120
130
140
150
160
170
(3)
Rainfall
distri-
bution
% of Pt
0.0166
0.0166
0.0166
0.0200
0.0200
0.0200
0.0226
0.0226
0.0226
0.0334
0.0334
0.0334
0.0778
0.0778
0.0778
0.0334
0.0334
(4)
Inae-
mental
Rainfall
in.
0.0113
0.0113
0.0113
0.0136
0.0136
0.0136
0.0154
0.0154
0.0154
0.0227
0.0227
0.0227
0.0529
0.0529
0.0529
0.0227
0.0227
(5)
Accumu-
lated
Rainfall
in.
—jmw
0.0226
0.0339
0.0475
0.0611
0.0747
0.0900
0.1054
0.1208
0.1435
0.1662
0.1889
0.2418
0.2947
0.3476
0.3703
0.3930
Pervious
(6)
Accumu-
lated
Runoff
in.
—ujsm—
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
o.oooa
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
Area
(7)
Incre-
mental
Runoff
in.
Impervious Area
(8)
Accumu-
lated
Runoff
in.
0.0000
0.0000
0.0000
0.0002
0.0018
0.0048
0.0096
0.0155
0.0225
0.0344
0.0477
0.0623
0.0997
0.1407
0.1842
0.2034
0.2230
(9)
Incre-
mental
Runoff
in.
0.0000
0.0000
0.0000
0.0002
0.0016
0.0030
0.0047
0.0060
0.0070
0.0119
0.0134
0.0146
0.0374
0.0410
0.0435
0.0192
0.0195
(10)
Total
Runoff
in.
0.0000
0.0000
0.0000
0.0001
0.0004
0.0007
0.0012
0.0015
0.0017
0.0030
0.0033
0.0036
0.0094
0.0103
0.0109
0.0048
0.0049
(11)
Instant
hydro-
graph
cfs
—UW
0.00
0.00
0.01
0.07
0.13
0.21
0.26
0.31
0.52
0.59
0.64
1.66
1.82
1.92
0.85
0.86
(12)
design
hydro-
graph
cfs
WW
0.00
0.00
0.00
0.03
0.08
0.14
0.20
0.26
0.36
0.49
0.58
0.96
1.48
1.74
1.51
1.07
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
<«peak
3-14-RWQB-SBUH-CDS-VORTECH xls 1 of 2
La Costa Oaks South 3.14 - Storm Water Quality Facility Sizing
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12)
Time Time Rainfall Incre-Accumu-Accumu-Incre-Accumu-Incre-Total Instant design
Increment distri-mental lated lated mental lated mental Runoff hydro-hydro-
bution Rainfall Rainfall Runoff Runoff Runoff Runoff graph graph
min. %0fPt In. in. in. In. in. in. In. cfs cfs
18 180 0.0334 0.0227 0.4157 0.0000 0.0000 0.2427 0.0198 0.0043 0.66 0.04
19 190 0.0316 0.0215 0.4372 0.0000 0.0000 0.2617 0.0189 0.0047 0.84 0.88
20 200 0.0316 0.0215 0.4587 0.0000 0.0000 0.2808 0.0191 0.0048 0.85 0.86
21 210 0.0316 0.0215 0.4802 0.0000 0.0000 0.3000 0.0193 0.0048 0.85 0.85
22 220 0.0234 0.0159 0.4961 0.0000 0.0000 0.3144 0.0143 0.0036 0.64 0.78
23 230 0.0234 0.0159 0.5120 0.0000 0.0000 0.3288 0.0144 0.0036 0.64 0.68
24 240 0.0233 0.0158 0.5278 0.0000 0.0000 0.3432 0.0144 0.0036 0.64 0.65
25 250 0.0213 0.0145 0.5423 0.0000 0.0000 0.3565 0.0132 0.0033 0.59 0.63
26 260 0.0213 0.0145 0.5568 0.0000 0.0000 0.3698 0.0133 0.0033 0.59 0.60
27 270 0.0213 0.0145 0.5713 0.0000 0.0000 0.3831 0.0133 0.0033 0.59 0.59
28 280 0.0175 0.0119 0.5832 0.0000 0.0000 0.3941 0.0110 0.0027 0.49 0.56
29 290 0.0175 0.0119 0.5951 0.0000 0.0000 0.4051 0.0110 0.0028 0.49 0.51
30 300 0.0175 0.0119 0.6070 0.0000 0.0000 0.4162 0.0111 0.0028 0.49 0.50
31 310 0.0183 0.0124 0.6194 0.0000 0.0000 0.4278 0.0116 0.0029 0.51 0.50
32 320 0.0183 0.0124 0.6319 0.0000 0.0000 0.4394 0.0116 0.0029 0.51 0.51
33 330 0.0183 0.0124 0.6443 0.0000 0.0000 0.4510 0.0116 0.0029 0.52 0.51
34 340 0.0175 0.0119 0.6562 0.0000 0.0000 0.4622 0.0112 0.0028 0.49 0.51
35 350 0.0175 0.0119 0.6681 0.0000 0.0000 0.4733 0.0112 0.0028 0.49 0.50
36 360 0.0175 0.0119 0.6800 0.0000 0.0000 0.4845 0.0112 0.0028 0.50 0.50
37 370 0.0000 0.0000 0.6800 0.0000 0.0000 0.4845 0.0000 0.0000 0.00 0.33
38 380 0.0000 0.0000 0.6800 0.0000 0.0000 0.4845 0.0000 0.0000 0.00 0.11
39 390 0.0000 0.0000 0.6800 0.0000 0.0000 0.4845 0.0000 0.0000 0.00 0.04
40 400 0.0000 0.0000 0.6800 0.0000 0.0000 0.4845 0.0000 0.0000 0.00 0.01
41 410 0.0000 0.0000 0.6800 0.0000 0.0000 0.4845 0.0000 0.0000 0.00 0.00
42 420 0.0000 0.0000 0.6800 0.0000 0.0000 0.4845 0.0000 0.0000 0.00 0.00
43 430 0.0000 0.0000 0.6800 0.0000 0.0000 0.4845 0.0000 0.0000 0.00 0.00
44 440 0.0000 0.0000 0.6800 0.0000 0.0000 0.4845 0.0000 0.0000 0.00 0.00
45 450 0.0000 0.0000 0.6800 0.0000 0.0000 0.4845 0.0000 0.0000 0.00 0.00
46 460 0.0000 0.0000 0.6800 0.0000 0.0000 0.4845 0.0000 0.0000 0.00 0.00
47 470 0.0000 0.0000 0.6800 0.0000 0.0000 0.4845 0.0000 0.0000 0.00 0.00
48 480 0.0000 0.0000 0.6800 0.0000 0.0000 0.4845 0.0000 0.0000 0.00 0.00
Time: 8.0 hours
(Found by summing this column and multiplying by 600. 600 is the conversion
required to convert SUM(Q) in cfs to total volume in cubic feet as follows:
V = SUM(Q)xdt
(cu.ft.) = (cu.ft/s) x (10 min.) x (60 s/min.)
Total Volume of Runoff =
Peak Hour Rainfall Intensity =
Total Flowrate of Runoff =
12870 cu.ft.'
0.30 ac-ft
0.227 In/hr
1.74 cfs
3-14-RWQB-SBUH-CDS-VORTECH xls 2 of 2
IX
La Costa Oaks South (Neighborhood 3.14)
Addendum to Storm Water Management Plan
CHAPTER 9 - SITE BMP DESIGN
VORTECHS TREATMENT UNITS
9.1 - BMP Locations
The site design includes four Vortechs treatment units (shown on BMP Location
Maps located on the following pages.
- Portions of Neighborhood 3.08 drain to the San Marcos Creek watershed
via an existing inlet to the old Rancho Santa Fe storm drain system. Prior
to discharge to the existing storm drain system, 85*^ percentile runoff will
be treated in an offline Vortechs Model 2000 (near Paseo Conifera). In
developed conditions, the developed condition drainage area from the site
area to the San Marcos Creek watershed is roughly 24 acres.
Runoff from Neighborhood 3.09 discharges to a storm drain system
constructed along with the new alignment of Rancho Santa Fe Road. Prior
to discharge to the Rancho Santa Fe storm drain system, 85*^^ percentile
flow will be treated in an offline Vortechs Model 1000. In developed
conditions, the contributing drainage area to this treatment unit is roughly
14 acres.
- At the southeast corner of the Oaks South site, a 5-acre watershed
discharges to a side canyon near Avenida Junipero. Prior to discharge to
the natural canyon, 85"^ percentile flow will be treated in an offline
Vortechs Model 1000.
Runoff from street areas not reaching the Water Quality Basin will be
treated in an offline Vortechs Model in La Costa Avenue. The developed
area from La Costa Oaks South to this treatment unit is 2 acres.
9.2 - Determination of Design Treatment Flows
The 85*^ percentile design flow rates have been calculated using the Rational
Method. Required data for the Rational Method treatment flow determination include
the following:
Runoff Coefficient I
Rainfall Intensity (I) = 0.20 inches per hour
Drainage area to treatment unit (A)
Runoff coefficients were derived based upon a weighted average of each area
tributary to the treatment unit and the associated runoff coefficient.
EM:smm h:\sw quallty\2352\39\3.14.doc
W.O. 2352-39 8/20/03 10:50 AM
LEGEND
! WATERSHED BOUNDARY ^ —
'BASIN WATERSHED BOUNDARY
I NEIGHBORHOOD BOUNDARY
AREA U-o-^ ^1
BMP LOCATION M*P FOR
NEIGHBORHOOD 3.09
VORTECHS UNIT
CAflt.SBAD. CALIFORNIA
rCJUALITY-
^BASIN;
LEGEND
WATERSHED BOUNDARY
BASIN WATERSHED BOUNDARY
. ( NEIGHBORHOOD BOUNDARY
AREA
BMP LOCATION MAP FOR SHEET
LA COSTA AVENUE 1
VORTECHS UNIT
La Costa Oaks South (Neighbortiood 3.14)
Addendum to Storm Water Management Plan
The following table summarizes the parameters used for determination of design
flows to each of the Vortechs treatment units.
DESIGN RUNOFF DETERMINATION SUMMARY TABLE
Treatment
Unit
Runoff
Coefficient
(C)
Rainfall
Intensity
(in/hr)
Drainage
Area
(acres)
85"' Pot.
Design Flow
(cfs)
Neigh. 3.08 0.49 0.2 23.9 2.3
Neigh. 3.09 0.49 0.2 13.7 1.3
Avenida Junip 0.49 0.2 5.4 0.5
La Costa Ave 0.85 0.2 2.1* 0.4
Developed area from La Costa Oaks South
9.3 - Vortechs Treatment Unit Selection
Each of the proposed Vortechs units is an offline precast treatment unit. The 85'^
percentile design flow rate is forced into the treatment area by a diversion weir built
in the upstream junction. Flows in excess of the design flow rate pass over the weir
and proceed downstream.
The following table shows the treatment capacities of each of the (4) proposed
Vortechs units.
VORTECHS UNIT TREATMENT CAPACITY TABLE
Treatment
Unit
85"^ Pet.
Design Flow
(cfs)
Recommended
Vortechs
Model
Treatment Capacity
(cfs)
Neigh. 3.08 2.3 2000 2.8
Neigh. 3.09 1.3 1000 1.6
Avenida Junip 0.5 1000 1.6
La Costa Ave 0.4 1000 1.6
EM:smm h:\sw quallty\2352\39\3.14.doc
W.O. 2352-39 8/20/03 10:50 AM
^GiiiChaiabeT ,^„^
t-+,Hjne swirling motion created by the'
- |-^,tangential inlet directs settleable i^-^
solids toward the center of this iJ""
111 i I iJ^'--r'i?!'-y'"'-i:::':':
..w..-..a..,»j.-»^l,v,.,T,.wl-.fc.t.-.3.:;a^^-a;
1) Initial Wet Weather Phase
During a twonnonth storm event the water level begins to
rise above the top of the inlet pipe. This influent control
feature reduces turbulence and avoids resuspension
of pollutants.
2) Transition Phase
As the inflow rate increases above the controlled outflow
rate, the tank fills and the floating contaminant layer acct>
mulated from past storms rises. Swirling action increases
at this stage, while sediment pile remains stable.
3) Full Capacity Phase
When the high-fiow cutlet approaches full discharge, stnmi
drains are flowing at peak capacity The Vbrtechs System is
designed to match your design storm flow and provide treat-
ment throughout the range of storm events without bypass-
ing. To accommodate very high flow rates, Vortechnics can
assist designers with configuring a peak-flow bypass.
4) Storm Subsidence Phase/Cleaning
Treated runoff is decanted at a controlled rate, restoring the
water level to a low dryweather volume and revealing a conical
pile of sediment The low water level facilitates inspection and
cleaning, and significantly reduces maintenance costs. The
system's central baffle prevents transfer of floatables to the
outlet during cleaning or during the next storm.
I
Stormwater Treatment System
PerfbralBd Covers
INV.
ffto 9'
Typical
"7 Seel
3toA!
Plan View
To begin the design of your
Vortechs System, refer to the
sizing chart below and com-
plete a Specifier's Worksheet to
provide details about your site
and design flows. Then simply
fox or mail the worksheet to
Vortechnics with your site plan,
and we'll produce detailed
Vbrtechs System scale draw-
ings free of charge.
Bevation View
•Vortechs;"".;:
• ,: .,Model
'f Gric Chamber • •
' Diameter/Area..';
:\ , ;:v: ft/ft?::/V s'-
.; -. '^ Peak : ; ^ • .• Design •
;..: Flow* •:.
• Sediment, '-
. Storage^
..• yds^.. :
Approx; .
Size? - Vi''-. LxW'--H
• ft ^iJ;
t^:4/13 •
l^i 5/20 • 4.5 ,
6.0 •::^iifl •
• '8.5. />•...
• :, ::";^n.a -^^^^ ^^^^^
-
' '-7.0^
; • A),Fcr lrv!in8 Vbrtechs Systems withcLt a bypass, sizing critBp'a ia baaed an pravicirg ore scjuara fcnt uf jrt '
•//..' .chamber sijrfaca.arBa.for- ;Bach, •too gpr^^ paaK design, sttrtp flew rBiB (B.g.^:10^Bar storml. . For mora . •
• ; dBtaila.ahaiit\tonachnic3 sizing cnto^
V iB) Siadirnani; storage yo^ . . / •
';'i;:V.,Q' CoOstruction details, may vary daparding on the specifiaapplicaaon. Any altaratioiis to fe siiing clnart spacifr-<v
i:i cations will appear an;\fartachnic3 dimensicnai and shop drawings.: fleasa call: Vbrtachnics.for tha weight of spa-
cifiC:.Vbrt8ch^'3ystarna\irneaded;v:.^ .v;;u;?'t^ViiS.\v^?^'S^f ^;'.':;'' ''.:..'li'V''vi[y^i:j''^"-y: <•
;-^#Sp«;ial:N6t8':. m stqraga: .capac'itit When it is naadad to meat .a spacilic raquireniant'for^^^ can ba -
i,iiA^Bd tn maatithB storage requirament with tha salecterfiTiodBtVortBchnicsltschnicat statf.will opOmiza system '
^^'•^Mmatry to meM containrnart re^
^h'li^rtc SpedficaCim-(^ VortBclmici.at(3l07) ays^BeSSJ^^if^iSii-SrV}:!^^ -'
f
Vortechs System Inlet/Outlet Configurations
Vortechs Systems con be configured to accommo-
date various inlet and outlet pipe orientations.
The inlet pipe can enter the end or side of the
tank at right angles - outlet pipes can exit the end
or the side of system at most angles.
End Inlet
)
1 Side Inlet
Pretreatment Q^^^„
SECTION 02721
STORMWATER TREATMENT SYSTEM
PART 1 .on nFMFRAi
1.01 DESCRIPTION
A. Work included:
The Contractor, and/or a rnanufacturer selected by the Contractor and approved
by the Engineer, shall fumish ail labor, materials, equipment and incidentals
required and install all precast concrete stomiwater treatment systems and
appurtenances in accordance with the Drawings and these specifications.
B. Related work described elsewhere:
1. Unit Masonry
2. Miscellaneous Metals
3. Waterproofing
1-02 QUALITY cnNTRQL INRPFnTinNl
A. The quality of materials, the process of manufacture, and the finished sections
shall be subject to inspection by the Engineer. Such inspection may be made at
me place of manufacture, or on the work site after delivery, or at both places and
the sections shall be subject to rejection at any time if material conditions fail'to
meet any of the specification requirements, even though sample sections may
have been accepted as satisfactory at the place of manufacture. Sections
rejected after delivery to the site shall be marked for identification and shall be
removed from the site at once. All sections which have been damaged beyond
repair during delivery will be rejected and. if already installed, shall be repaired to
the Engineer's acceptance level, if pemiitted. or removed and replaced, entirely
at tiie Contractor's expense.
All sections shall be inspected for general appearance, dimensions, soundness
etc. The surface shall be dense, close textured and free of blisters cracks
roughness and exposure of reinforcement
Imperfections may be repaired, subject to the acceptance of the Engineer after
demonstration by ttie manufacturer tiiat strong and permanent repairs result
Repairs shall be carefully inspected before final acceptance. Cement mortar
used for repairs shall have a minimum compressive strengtii of 4 000 psi at ttie
end of 7 days and 5.000 psi at the end of 28 days when tested in 3 inch diameter
by 6 inch long cylinders stored in ttie standard manner. Epoxy mortar may be
utilized for repairs.
B.
1.03 SUBMITTALS
A. Shop Drawings
The Centimeter shall be provided with dimensional drawings and. when specified,
utilize these drawings as tiie basis for preparation of shop drawings showing
details for constiuction, reinforcing, joints and any cast-in-place appurtenances.
Shop drawings shall be annotated to indicate all materials to be used and all
applicable standards for materials, required tests of materials and design
assumptions for stiuctural analysis. Design calculations and shop drawings shall
be certified by a Professional Engineer retained by tiie system manufacturer or
contimctor and licensed in the state where tiie system is to be installed. Shop
drawings shall be prepared at a scale of not less tiian 1/4" per foot Six (6) hard
copies of said shop drawings shall be submitted to ttie Engineer for review and
approval.
B. Affidavit on patent Infringement
The Contimctor shall submit to tiie Engineer, prior to installation of the stormwater
treatinent system, an affidavit regarding patent infringement rights stating ttiat
any suit or claim against ttie Owner due to alleged Infringement rights shall be
defended by the Contimctor who will bear all ttie costs, expenses and attomey's
fees incun-ed ttiereof.
PART 2.00 PRODUCTS
2.01 MATERIALS AND DESIGN
A. Concrete for precast stomiwater ti-eatment systems shall confomn to ASTM
C 857 and C 858 and meet the following additional requirements:
1. The wall thickness shall not be less tiian 6 inches or as shown on the
dimensional drawings. In all cases the wall thickness shall be no less tiian
the minimum thickness necessary to sustain HS20-44 loading requirements
as determined by a Licensed Professional Engineer.
2. Sections shall have tongue and groove or ship-lap joints with a butyl mastic
sealant confomning to ASTM C 990.
3. Cement shall be Type III Portland cement conforming to ASTM C 150.
4. Pipe openings shall be sized to accept pipes of tiie specified size(s) and
material(s), and shall be sealed by the Contiractor with a hydraulic cement
confomning to ASTM C 595M
5. Internal metal components shall be aluminum alloy 5052-H32 In accordance
witii ASTM B 209.
6. Brick or masonry used to build tiie manhole frame to grade shall confonn to
ASTM C 32 or ASTM C 139 and tiie Masonry Section of these Specifications.
\\MDI\SYS\DATA\V0RTECHN\EMA1L\STDETAIL\VCRTSPEC.D0C SECTION 02721 Page 2
7. Casting for manhole frames and covers shall be in accordance witii The
Miscellaneous Metals Section of these Specifications.
8. All sections shall be cured by an approved metiiod. Sections shall not be
shipped until the concrete has attained a compressive strengtii of 4,000 psi or
util 5 days after fabrication and/or repair, whichever is the longer.
A butimen sealant in confonnance with ASTM C 990 shall be utilized in
affixing the aluminum swiri chamber to tiie concrete vault
2.02 PERFORMANCF
Each stormwater treatinent system shall adhere to tiie following perfonnance specifications
at the spedfied design flows, as listed below:
able 2.02
Vortechs
Model
Swirl
Chamber
Diameter
(ft)
Design
Treatment
Capacity
(cfs)
Sediment
Storage
(yd^)
1000 3.67 2.3 1.00
2000 4 2.8 1.25
3000 5 4.5 1.75
4000 6 6.0 2.50
5000 7 8.5 3.25
7000 8 11.0 4.00
9000 9 14.0 4.75
11000 10 17.5 5.50
16000 12 25.0 7.00
Each stonnwater ti-eatment system shall include a circular aluminum "swiri chamber" (or "grit
chamber") with a tangential inlet to induce a swiriing flow pattern that will accumulate and
store settieable solids in a manner and a location that will prevent re-suspension of previously
captured particulates. Each swiri chamber diameter shall not be less tiian ttie diameter listed
in Table 2.02 (neglecting chamber wall ttiickness).
Each stonnwater ti^atinent system shall be of a hydraulic design tiiat includes flow conti-ols
designed and certified by a professional engineer using accepted principles of fluid mechanics
that raise the water surface Inside the tank to a pre-determined level in order to prevent ttie
re-entrainment of trapped floating contaminants.
Each stormwater tireatinent system shall be capable of removing 80% of tiie net annual Total
Suspended Solids (TSS). individual stormwater treatinent systems shall have the Design
Treatment Capacity listed in Table 2.02, and shall not resuspend trapped sediments or re-
enti-ain floating contaminants at flow rates up to and induding the specified Design Treatment
Capacity.
Individual stonnwater ti-eatment systems shall have usable sediment storage capacity of not
less than ttie con-esponding volume listed in Table 2.02. The systems shall be designed such
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that ttie pump-out volume is less than Va of ttie total system volume. The systems shall be
designed to not allow surcharge of ttie upsti-eam piping network during dry weather conditions.
A water-lock feature shall be incorporated into tiie design of the stormwater treatment system
to prevent the intinoduction of trapped oil and floatable contaminants to Oie downstream piping
during routine maintenance and to ensure that no oil escapes the system during tiie ensuing
rain event Direct access shall be provided to the sediment and floatable contaminant storage
chambers to fadiitate maintenance. There shall be no appurtenances or restrictions within
tiiese chambers.
The stonnwater ti-eatinent system manufacturer shall fumish documentation which supports
all product perfonnance daims and features, storage capaciti'es and maintenance
requirements.
Stormwater ti-eatinent systems shall be completely housed within one rectangular stiucture.
2.03 MANUFACTllRFP
Each stonnwater ti-eattnent system shall be of a type that has been installed and used
successfully for a minimum of 5 years. The manufacturer of said system shall have
been regulariy engaged In tiie engineering design and production of systems for the
physical ti-eatinent of stomiwater runoff.
Each stormwater ti-eatment system shall be a Vortechs™ System as manufactured by
Vortechnics, inc.. 41 Evergreen Drive, Portiand, Maine 04103, phone: 207-878-3662 ^
fax: 207-878-8507; and as protected under U.S. Patent #5,759,415.
PART3.QQ EXFCIITinM
3.01 INSTALLATION
A. Each Stormwater Treatinent System shall be constiucted according to ttie sizes
shown on the Drawings and as specified herein. Install at elevations and
locations shown on tiie Drawings or as otherwise directed by tiie Engineer.
B. Place tiie precast base unit on a granular subbase of minimum tiiickness of six
inches after compaction or of greater tiiickness and compaction if specified
elsewhere. The granular subbase shall be checked for level prior to setting and
tiie precast base section of the tiap shall be checked for level at all four comers
after it is set If tiie slope fi-om any comer to any ottier comer exceeds 0.5% the
base section shall be removed and ttie granular subbase material re-leveled.
C. Prior to setting subsequent sections place butimen sealant in conformance with ASTM
C990-91 along the constiuction joint in tiie section that is already in place.
D. After setting tiie base and wall or riser sections install tiie circular swiri chamber
wall by bolting ttie swiri chamber to tiie side walls at ttie three (3) tangent points
and at the 3-inch wide inlet tab using HILTI brand concrete anchors or equivalent
1/2-inch diameter by 2-3/4" minimum length at heights of approximately three
inches (3") off ttie floor and at ttie mid-height of tiie completed ti-ap (at locations
of pre-drilled holes in aluminum components). Seal the bottom edge of the swiri
\\MDI\SYS\DATA\V0RTECHN\EMA1L\STDETA1L\V0RTSPEC.D0C SECTION 02721 Page 4
chamber to the ti-ap floor with tiie supplied aluminum angle flange. Adhere VA
thick by 1" wide neoprene sponge material to the flange with half of it's width on
the horizontal leg of tiie flange and half of if s widtii on the vertical leg. The
aluminum angle flange shall be affixed to tiie floor with a minimum 3/8" diameter
by 2-3/4" drop in wedge anchor at tiie location of the predrilled holes. Affix the
swiri chamber to ttie flange with hex head V* x 1-1/2" zinc coated self- tapping
screws at ttie location of the predrilled holes. Seal ttie vault sidewalls to the
outside of ttie swiri chamber from ttie floor to ttie same height as ttie inlet pipe
invert using butyl mastic or approved equal.
E. Prior to setting ttie precast roof section, butimen sealant equal to ASTM C990 shall be
placed along tiie top of tiie baffle wall, using more than one layer of mastic if
necessary, to a tiiickness at least one inch (1") greater ttian tiie nominal gap between
the top of the baffie and the roof section.
The nominal gap shall be detemiined eitiier by fleld measurement or the shop
drawings. After placement of ttie roof section has compressed ttie butyl mastic sealant
in the gap, finish sealing ttie gap witti an approved non-shrink grout on both sides of
tiie gap using the butyl mastic as a backing material to which to apply the grout Also
apply non-shrink grout to tiie joints at the side edges of the baffle wall.
F. After setting ttie precast roof section of the stonnwater treatment system, set
precast concrete manhole riser sections, to the height required to bring the cast
iron manhole covers to grade, so tiiat the sedions are vertical and in bue
alignment witii a 1/4 inch maximum tolerance allowed. Backfill in a careful
manner, bringing the fill up in 6" lifts on all sides. If leaks appear, dean tiie inside
joints and caulk with lead wool to the satisfadion of the Engineer. Precast
sedions shall be set In a manner that will result in a watertight joint In all
instances, installation of Stonnwater Treatinent Systems shall confonn to ASTM
specification C891 "Standard Pradice For Installation of Underground Precast
Utility Stiudures".
G. Plug holes in the concrete sections made for handling or other purposes with a
nonshrink grout or by using grout in combination with concrete plugs.
H. Where holes must be cut in tiie precast sections to accommodate pipes, do all
cutting before setting the sedions in place to prevent any subsequent jarring
which may loosen tiie mortar joints. The Contrador shall make all pipe
connections.
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VORTECHS™ STORMWATER TREATMENT SYSTEM
DESIGN AND OPERATION
Basic Operation
fmm^cfl!^^^ f^^^®"" i ^^^"^ °" °^ '•®"'°^'"9 sediment and floating pollutants
from stomiwater runoff. When the system is operating at its peak design capadr the
m^irnum serv ce rate wiil be appro)dmately 100 gallons-per-minute per square foot ^f grrt
charnber area (gpm/sf). The Vortechs System has been tested for flows up to and including
rangT rate and has been shown to produce positive removal efficiendes throughout this
Tbtel^?M!ntnw^H'?'?-J^" ^'?:!^^ ^ of 80% removal of
Thl /f^r o®^ ^^^^ ^P'^"y encountered in runoff from urtjan environments
The Vortechs System will also effectively capture and contain floatables in stomiwater mnoff. '
SntiTtJp^iiS'^l''''®?®^ a swiriing motion that directs settleable solids into a pile towards the
t?rnL L^r f^"""®'- 5®^""ent IS caught in ttie swiriing flow patti and settles back onto
r^ntr!f I ^ f^'o^tabtes entrapment is achieved by sizing ttie low flow
"pe in me 2^^^^^^ " '''' ^° ^*"^* '"'^^
The Vortechs System is designed to create a badcwater condition within the system in order to
JSiTh^n®^®T« a"^°unt of backwater varies and is detemiined by the
conSs "°°'^'"^* °^ ^y^*®"" incorporates all site
Design Process
Duriiig tiie Vortechs System design process consideration Is given to botti the physical
consti-aints of ttie site and the site-specific flows. Each system is designed differently based on
ttlfex^dTd Ss"^' ^""^ spedfically designed to accommodate
The site engineer provides ttie Vortedis System rim and invert elevations, pipe sizes, design
Tiow rate and design stomn recunrence interval Another consideration is whether ttie system is
in an on-line or off-line (i.e. bypassed) configuration. If regulatory autiiorities allow ti-eatinent of
w conveyance capadty of the piping system, it may be possible to
provide a Vortechs System in an off-line configuration which will result in a cost savings witiiout
a significant reduction in pollutant removal efficiency.
Sizing the Sysfam
Each system is custom designed based on the design conditions provided. The weir orifice
sump depth, and height of tank will vary depending on ttie site conditions and performance
requiremente. The rim and invert elevations will impad the overall height of ttie unit ttie sump
aeptti. and the placement of the weir and orifice. Also affecting the placement of the weir and
VORTECHS™ STORMWATER TREATMENT SYSTEM
orifice is tiie pipe size, the orientation of ttie internal walls, and the potential for tailwater. The
flow rates detemiine the size of ttie weir, orifice, and tiie baffle opening.
Sj^: The size of the system depends on whether or not the system is on-line or off-line. An
on-line system will be chosen such ttiat tiie design flow rate Is equal to or less ttien ttie
Vortechs rated design flow. For an off-line system, the 2-month flow rate is determined and ttie
model number is chosen based on tiie grit chamber area such tiiat 24 gpm/sf of flow is realized
tiirough the chamber.
SurnB: Typically a three-foot sump depth is provided In Vortechs Systems. This depth Is most
conimon since it provides ample sediment storage and keeps the excavation depth to a
minimum. However, because each Vortechs System is custom designed, the individual sump
deptiis may vary to balance maintenance costs with capital costs.
prffire: The function of tiie orifice is to raise the water level in tiie Vortechs System. This
increases tiie area of ttie flow in the pipe, which decreases ttie velodty of tiie water flowing into
the system. A reduction in turtDuience is realized at the inlet; ttiis aids in keeping the trapped
sediment and floatables contained. In addition, ttie rise in water level causes ttie floatables to
rise above the inlet and away from the baffle opening, thus preventing tiie floatables from
becoming re-entrained and pulled under the baffle wall. The orifice is designed to pass a flow
approximately equal to tiiat of a 2-month stonn event
Wei£: Any event greater than ttie 2-montti event causes ttie water level in ttie Vortechs System
to rise to ttie upper flow control, submerging ttie inlet The upper flow conti'ol is nonnaily a fl
Cippoletti weir. A Cippoletti weir is a ti-apezoidal weir witti 4 to 1 sloping sides. Like ttie orifice, ^
ttie weir also causes tiie water level in tiie system to rise, which promotes sediment and
fioatable removal. As the water rises, ttie volume of water in the system increases, ttius
stabilizing the detention time and allowing sediment to settle out. The swiri is maintained by
allowing continuous flow through ttie system via the weir and orifice. The weir is sized to pass
the design fiow rate minus the orifice flow at full head.
Baffle: The baffle opening is designed to maintain a velodty such tiiat re-enti-ainment of
floatables and re-suspension of sediment is minimized. The baffle opening is at least 6 inches
to ensure against dogging. The largest opening of 15 inches is chosen to maximize ttie
distance between ttie floatable layer and ttie baffle opening. This keeps ttie floatables ti-apped
and maintains ttie oil storage volume. In most applications, tiie flow under ttie baffle wall is
approximately 1.0 foot per second.
bypass: For systems in an off-line configuration, a weir crest length and elevation is calculated
for ttie diversion stiudure tiiat will be installed upstream of the specified Vortechs System. The
goal is to achieve a water surface elevation during tiie 100-year storm tiiat is at ttie same
elevation as the top of tiie Vortechs Cippoletti weir. The area of fiow over the bypass weir is
calculated based on the 100-year flow. From this area, ttie height of flow Is solved for a given
weir length. Since ttie area of flow remains constant the height of flow over tiie weir varies with
ttie bypass weir length. See Technical Bulletin 3A for more information.
VORTECHS STORMWATER TREATMENT SYSTEM
FlnwCnntroir^HnthtinnT Vortechs Model 5000
System
The Vortechs System W.Q.S. 1 is a Model 5000 with a 7.0-foot diameter grit chamber. In
this application, the runoff rate for a rainfall event with a retum frequency of 10 years is 6 13
cubic feet per second (cfs). The system design flow is 2751 gpm (6.13 cfs). The surface
area of the grit chamber is 38.5 square feet, ttierefore the peak operating rate is 2751
divided by 38.5 or 72 gpm/sf.
The low flow control is a ti-apezoidal orifice (Qoria»). Since the inlet is a 24-inch diameter
pipe, ttie orifice must raise the water level 24 inches, or 2.0 feet, in a 2-montti storni to
submerge the inlet pipe. Acconding to Vortechnics Technical Bulletin #3, ttie 2-montii stonn
flow rate is approximately equal to the 10-year flow rate divided by 7. The orifice calculation
based on tiie full design flow is as follows:
Q2-mona>s.Qioymu-+7 = 6.13 7 = 0.88 cfs
Qortflf s C(A)(2g/J)°» = 0.56(0.14)(2.0 x 32.2 x 2.0) = 0.89 ds 4
Where C = Orifice conti^dion coeffident = 0.56 (based on Vortechnics laboratory testing)
A = Orifice flow area, ft' (calculated by Vortechnics technical staff)
h = Design head, ft (equal to the inlet pipe diameter)
A Cippoletti weir configuration is utilized as the high flow conti-ol (Qw*-) which is
conservatively designed for the system design flow (Qdaign) of 6.13 cfs. The weir
calculations are as follows:
Qwrtir =6.13 cfs
Qmir =C{L){H)'^ = 3.37(0.50)(2.42)'-* =6.34 cfs 4
Where C = Cippdetti Weir coeffident = 3.37 (based on Vortechnics laboratory testing)
Available head, ft (height of weir)
^ = Design weir crest lengtti, ft (calculated by Vortechnics technical staff)
VORTECHS™ STORMWATER TREATMENT sygrEM
MAINTENANCE
inspection
rorSm^ili!!" ."^^ *° maintenance and it is easily performed. Vortedinics
recommends ongoing quarteriy Inspedions of ttie accumulated sediment Note thaffe i^t
unusual for sediment accumulation to be relatively light in tiie first year Sln Jsed^^^^
.n new stomi drainage systems may be diverted to c^tdi basin sumps ?oIlCtent d^^^^^^^^
S^^AM ^^"^ *° ^"^ ^"^^^'^y ^"^P«^°n« wlirhelp inlrft^at^^^^^^^ deaned out at ttie appropriate time, inspedions should be perfomied more oten In th! wttlr
^^^Z'^"'^'''.:^''' "'"''"9 '^^d *° ^P'd SuTationf o?i?eq^^^^^^^^
so fs PZ^'''- "*° '^'P ''''''' A simple fclTdo^
The Vortechs System only needs to be deaned when inspection reveals ttiat It is neariv full-
Sir mi detemiination can be made by taking 2 measurements witti a stadia rod o
ton of t^lfoH-"^ devrce: one measurement is the distance from ttie manhole openS^^ to the
lurfaL If ^'^^ ^1?^^ ^'^^"^^ '"^"hote opening to ttie water
K I?: L*^® difference between ttie two measurements is less ttian six Indies ttie svstem
should be deaned out Note: to avoid underestimating ttie volume oTs^mJnt 1^ S^^c^^^^^^
partdes at ttie top of ttie pite typically offer less resistance to ttie end of ttie ^d than I'araer
partides toward ttie bottom of ttie pile. ^
m«v°nnf ? ^here ttie risk of large peboteum spills is small, liquid contaminants
dean^S o?^^"'"'^i^^? '^''^^ '^^"^®"*- "°^^^«^' °" °^ S^s^'ine ^P"' should be -mnln K ''""^^^'^^^'y- O" that accumulates on a more routine basis should be removed when an appredable layer has been captured.
Cleaning
?nn!«nlf ^y^*®"" ^ "^^"""^ ^""^generally ttie most effedive and convenient mettiod. Cleanout should not occur wittiin 6 hours of a rain event to allow ttie entire
^c^tion'S r ^^'^T" 2°^- maintained Vortedis Systems will only require
nl!«r. ? *u °' ^ystom. in whldi case only ttie manhole cover
rh!mhi« ^ T?'" L"'®*^® °P®"®'' *° '^'"o^® water and contaminants. However, all
-ri«mshS.^- i!^ *° ®"^"'® '"*®9^^ °f ^« system. In installations where a
nHi!I?,f u ^°''^s P^o*" to removing ttie grit, absorbent pads or
^® placed in the oil chamber to remove floating contaminants. Once ttiis is done,
sediment may ttien be easily removed witti ttie clamshell.
VORTECHS™ STORMWATER TREATMENT SYSTEM
r" ^^^^ - f.!-
X
La Costa Oaks South (Neighborhood 3.14)
Addendum to Storm Water Management Plan
CHAPTER 10 - REFERENCES
"Standard Urban Stonn Water Mitigation Plan - Storm Water Standards" City of
Carisbad, April 2003.
"Standards for Design and Construction of Public Works Improvements in the City of
Carlsbad", City of Carisbad, California; April 1993.
"Master Drainage and Storm Water Quality Management Plan", City of Carisbad,
California; March 1994.
"Addendum to Preliminary Hydrology Study for Villages of La Costa - 77je Ridge and
The Oaks", Hunsaker & Associates San Diego, Inc.; Revised October 23, 2001.
"Hydrology Manual", County of San Diego Department of Public Works - Flood
Control Division; Updated April 1993.
"San Diego County Hydrology Manual- DRAFT', County of San Diego Department
of Public Works - Flood Control Section; September 2001.
"Order No. 2001-01, NPDES No. CAS0108758- Waste Discharge Requirements for
Discharges of Urban Runoff from the Municipal Separate Storm Sewer Systems
(MS4s) Draining the Watersheds of the County of San Diego, the Incorporated Cities
of San Diego County, and San Diego Unified Port District", California Regional
Water Quality Control Board - San Diego Region; February 21, 2001.
"Water Quality Plan for the San Diego Basin", California Regional Water Quality
Control Board - San Diego Region, Septembers, 1994.
"Vortechnics Storm Water Treatment System Manual", Vortechnics- Revised
May 2000.
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