HomeMy WebLinkAboutCT 02-22; VILLAGES OF LA COSTA GREENS NBHD 1.09; STORM WATER MGMT PLAN; 2004-06-17STORM WATER
MANAGEMENT PLAN
for
LA COSTA GREENS
NEIGHBORHOOD 1.09
City of Carlsbad, California
Prepared for:
Western Pacific Housing
5790 Fleet Street
Carlsbad, CA 92008
w.o. 1751-123
r
June 17, 2004
Eric Mosolgo, R.C.E
Water Resources Department Manager
Hunsaker & Associates San Diego, Inc.
pile JP9
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La Costa Greens Neighborhood 1.09
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
1.5 Conclusion
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
3.7 Bacteria & Viruses
3.8 Pesticides
CHAPTER 4 - Conditions of Concern
4.1 Receiving Watershed Descriptions
4.2 Pollutants of Concern in Receiving Watersheds
CHAPTER 5 - Flow-Based BMPs
5.1 Design Criteria
5.2 Vortechs Treatment Units
5.3 Pollutant Removal Efficiency Table
5.4 Maintenance Requirements
5.5 Scheduie of Maintenance Activities
5.6 Annual Operations & Maintenance Costs
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La Costa Greens Neighborhood 1.09
Storm Water Management Plan
CHAPTER 6 - Source Control BMPs
6.1 Landscaping
6.2 Urban Housekeeping
6.3 Automobile Use
6.4 Site Design BMPs
CHAPTER 7 - Site BMP Design (Vortechs Treatment Units)
7.1 BMP Locations
7.2 Determination of Treatment Flows
7.3 Vortechs Treatment Unit Selections
CHAPTER 8 - References
List of Tables and Figures
Chapter 1 - Watershed 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 6 - Pollutant Removal Efficiency Table (Flow-Based BMPs)
Chapter 7 - 85'^^ Percentile Rainfall Isopluvial Map
Chapter 7 - Neighborhood 1.09 BMP Location Map
Chapter 7 - Design Runoff Determination Summary Table
Chapter 7 - Vortechs Unit Treatment Capacity Table
Chapter 7 - Vortechs System Data
Attachments
BMP Location Map
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La Costa Greens Neighborhood 1.09
Storm Water Management Plan
CHAPTER 1 - EXECUTIVE SUMMARY
1.1 - Introduction
Phase 1 ofthe La Costa Greens project site is located north of Alga Road, south of
the proposed extension of Poinsettia Lane, and east ofthe La Costa Golf Course.
Neighborhood 1.09 is located roughly in the center of the development, east of
Alicante Road, north of Neighborhood 1.12 and south of Neighborhood 1.08.
Neighborhood 1.09 is one of seven subdivisions within the La Costa Greens Phase
development. An exhibit showing the location of each treatment unit and the
breakdown ofthe areas tributary to each treatment unit is included on the following
page.
All runoff from Neighborhood 1.09 will eventually drain to a proposed storm drain
outlet located at the southwest corner of Neighborhood 1.10 (at the Street KK cul-
de-sac). In addition to the flow contributed by Neighborhood 1.09, Neighborhood
1.10, the northern portion of Neighborhood 1.12, and offsite area from adjacent
residential developed areas east of La Costa Greens Phase 1 (totaling 98 acres) will
also drain to this storm drain outlet location. Runoff ultimately drains to an unnamed
tributary of San Marcos Creek. Flow from this tributary eventually discharges into
San Marcos Creek towards the Batiquitos Lagoon.
Per the City of Carlsbad SUSMP, the La Costa Greens Neighborhoods 1.09 project
is classified as a Priority Project and subject to the City's Permanent Storm Water
BMP Requirements.
CITY OF
SAN MARCOS
THE GREENS 1.9
\ \^
VICINITY MAP
NTS
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LEGEND
WATERSHED TRIBUTARY
TO TREATMENT UNIT
TREATMENT UNIT 0
OFFSITE RUN-ON LOCATION H
LA COSTA GREENS
POST-CONSTRUCTION
BMP LOCATION EXHIBIT
FLOW-BASED BMP FOR
NEIGHBORHOOD 1.08, OFFSITE DEVELOPMEl
AND AUCANTE ROAD
FLOW-BASED BMP FOR
NEIGHBORHOOD 1.09,
1.10, A PORTION OF 1.12,
AND OFFSITE DEVELOPMENT
FLOW-BASED BMP FOR
NElGHBORHOOD1.il
FLOW-BASED BMP FOR
NEIGHBORHOOD 1.13,1.14,
PORTION OF 1.12,
ALICANTE ROAD, AND
OFFSrrE DEVELOPMENT
Ri\0327\!.Hyd\Slte Location Mop 8.5xU.dw9C 1275]Jun-12-2003>l4i39
La Costa Greens Neighborhood 1.09
Storm Water Management Plan
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 setforth 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 a single Vortechs treatment unit (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 forthe design of flow-based and volume-
based BMPs.
1.2 - Summarv of Pre-Developed Conditions
Phase 1 ofthe La Costa Greens project site is located north of Alga Road, south of
the proposed extension of Poinsettia Lane, and east of the La Costa Golf Course.
Neighborhood 1.09 is located roughly in the center of the development, east of
Alicante Road, north of Neighborhood 1.12 and south of Neighborhood 1.08.
Runoff from the site in natural conditions drains to the San Marcos Creek. The
Regional Water Quality Control Board has identified 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
The La Costa Greens Neighborhood 1.09 project will include construction of two (2)
proposed roads, grading of the proposed site to make it suitable for construction of
single-family residential dwellings, construction of underground utilities typically
associated with residential developments, and the construction of 64 residences.
The proposed project site consists of 75 residential lots and 2 open space lots, for a
total area of 21.04 acres (14.83 acres and 6.21 acres respectively). Approximately
30% will remain undeveloped.
The offsite developed areas, which will drain to the storm drain outlet located in
Neighborhood 1.10 have been quantified in two hydrology studies; "Hydrology &
Hydraulic Study - La Costa Greens Phase 1", prepared by O'Day Consultants
May 25, 2002, and "Tentative Map Drainage Study for La Costa Greens - Phasel
Neighborhoods 1.08 through 1.14," prepared by Hunsaker & Associates San Diego,
Inc. April 17, 2003. The O'Day report identified a total of 98 acres of offsite
developed area that contribute flow to the La Costa development in the vicinity of the
1.09 and 1.12 Neighborhood. The Hunsaker & Associates report identified two run
on locations: one at the southeast corner of Neighborhood 1.09 consisting of 19
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La Costa Greens Neighborhood 1.09
Storm Water Management Plan
acres of area; and one at the northeast corner of Neighborhood 1.12 consisting of 79
acres of area. The offsite run on at the southeast corner of Neighborhood 1.09 will
be collected and piped through Neighborhood 1.09 and 1.10 to the outlet. The
Quadrangle Map Watershed Exhibit for La Costa Greens illustrates the extent of
offsite areas draining to the La Costa Greens Phase I proposed development and
has been included in the Attachment section of this report.
Development of the site will not cause any diversion to or from the existing
watershed to the storm drain system. . The proposed treatment unit will located
offline from the main storm drain system and proposed to be located in the vicinity of
the Street KK cul-de-sac (see Ultimate Condition Site Map included in the pocket of
the this report).
85* percentile runoff will be treated in a storm water BMP prior to discharge to the
existing storm drain and detention basin. Flows in excess ofthe treatment flow will
bypass the treatment unit.
A runoff coefficient of 0.63 was assumed for the proposed single-family residential
development, based on City of Carlsbad criteria.
1.4 - Results and Recommendations
Using the 85"^ percentile rainfall of 0.67 inches (see Isopluvial Map in chapter 7) and
assuming approximately 50 percent imperviousness in the contributing watershed
Table 1 below summarizes rational method 85*'' percentile calculations for the
proposed water quality treatment unit for the La Costa Greens Neighborhoods 1.09,
1.10 & 1.12 developments.
Table 1 - Developed Conditions BS*"^ Percentile Calculations
Area
Drainage
Area
(acres)
85*^
Percentile
Rainfall
(inches)
Rainfall
Intensity
(inches/hour)
Runoff
Coefficient
Percent
impervious
(%)
BMP
Treatment
Area
291.5 0.67 0.2 0.53* 50
Rational Method calculations predicted an 85"^ percentile runoff flow of roughly
30.9cfs for the area discharging to the storm drain. 85"^ percentile flows will be
treated in the proposed Vortechs unit priorto discharging to the Alicante Road storm
drain.
The proposed Vortechs unit is an offline precast treatment unit. The SS''^ percentile
design flow rate is forced into the treatment area by a diversion weir built in the
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La Costa Greens Neighborhood 1.09
Storm Water Management Plan
upstream junction. Flows in excess of the design flow rate pass over the weir and
proceed downstream.
A single Vortechs Model PCI6x24 will be required to meet the water quality
treatment requirements for Neighborhood 1.09. The proposed Vortechs Model
PCI6x24 will be located offline from the main storm drain system and is to be
located in the vicinity of the Street KK cul-de-sac.
1.5 - Conclusion
The combination of proposed construction and permanent BMP's will reduce, to the
maximum extent practicable, the expected project pollutants and will not adversely
impact the beneficial uses of the receiving waters.
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CARLSBAD
WATERSHED MAP FOR
LA COSTA GREENS
NEIGHBORHOOD 1.09
crrv OF CARLSBAD. CALIFORNIA
La Costa Greens Neighborhood 1.09
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 runoff 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 ofthe urban development ofthe 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 Carlsbad SUSMP, the La Costa Greens Neighborhood 1.09 project is
classified as a Priority Project and subject to the City's Permanent 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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1?^
-'^PENDKA
storm Watar standards
Does the project nrap«A; -__i_£H2ems^
Yea No
k www.avn;h io^3to,iMiMnri,riwjZr'^™ teourcea Control Boart web site
Sectton 2. Constmction Storm Water BMP Requirements-
a Storm Water PoS pr?v™n&^bn^ll^^^ "^"^ P^P^^^
a Water Pollution Sl SrWP^^^^ Standards,' and must prepare
prioritization in PaTo below. construction site
PglCLjDgtermlne Construction Phase Storm W^t^r p.^-..».,Tn-nt-
Would the project meet any of these criteria during construction? Yes No
praject subject to California's statewlda General NPOF'S Parr,,.» .., ,
Dj§charges Assodated Wrth Cs..^.^L^^^j}^^^^ P^""'* Storm Water
Does the project propose grading or soil disturfaanca?
cnn^';;ZT' H'^f ^aye the potential to contact any portion of the constnjction arga. including washing and staoing ama^9 ' ^ ;— ' —..r^ •.>.>.. M BUM amviint^ areas c
.•- project usa any constraction materials that could neaativeiv affpH- ./.«+or
31
^n'^^'' i'^"""^ Construction Sits Priori*,
!yi?°=?S1??i* *e Munidpal Pem* each ecn.,tn,Hi.„
Th?e r>Xl 'l V'fMuirements must be desianatpH «/Hh V"^'"-' 7'"' -^••"SuuCucn otorm
bai^'^' ^" """Aucfion BMP requiremeS M^^T'"™'* fat apply J*? <»nstnictian pnority does aSrf thn TS, on a case-by-case
requirements.] ' ^re details on construction BMP-
A) High Priority
Ka^n" ^ ™- S-^dlng « occur during the
. within an environmenteiy sS arts wate'r
P-^lects. active or inactive, acgacentcrtribttery to sensilive water bodies
• B) Medium Priority
" PoI"fon7Sc^'p«w^'p1=TrnS"^ "^^^ ' storni Water
Constnjction PeS 0 e s Jfr JTr*^ ^"^^ '^^"^^l
-<^*ee.re-alignmiS;«r„^,„tclSSSritc^
' ''^m^T.lZ^l'^^^^r'^. 9-^''na such as
ent.e.*.t,?o?S^r^%^errsTpS ^
«sreo?,SNgrsr^,s^
• • C; Low Priority
' ic«rsri;^it^jr^^^^^
ruc'!I"i''l3!*,""""S ['9f'*-<=fl«ay where minimal to no grading occurs such as pedestnan ramps. driveway^addiCons. small retaining Ls, etc ^
sue? af'"™,,?" ^I"?? ^"'^^^ grading pemiits are not required'
• m n^v^enrJ o ™' ^'"^'^'^"^ ^"'^^ ^nan
32
La Costa Greens Neighborhood 1.09
Storm Water Management Plan
CHAPTER 3 - IDENTIFICATION OF TYPICAL POLLUTANTS
3.1 - Anticipated Pollutants from Proiect Site
The following table details typical anticipated and potential pollutants generated by
various land use types. The La Costa Greens Neighborhoods 1.09 development will
consist of detached single-family residence. Thus, the Detached Residential
Development categories have been highlighted to clearly illustrate which general
pollutant categories are anticipated from the project area.
General Pollutant Categories
Priority
Project
Categories Sediments Nutrients Heavy IVIetals Organic Compounds Trash & Debris Oxygen Demanding Substances Oil & Grease Bacteria & Viruses Pesticides E^mmmm - \.« .
ISi'lSiffil wm IP
i^J&rmi 1^
..•(••*S5«.,sr m Attached
Residentiai
Development
X X X p(i) p(2) p X
Commercial
Development
>100,000 ft^
pd) pd) 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 pd) pd) X X pd) X p(1)
streets,
Highways &
Freeways
X pd) 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 Greens Neighborhood 1.09
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 urban 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 - Oxygen-Demanding 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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La Costa Greens Neighborhood 1.09
Storm Water Management Plan
3.7 - Bacteria & Viruses
Bacteria and viruses are ubiquitous microorganisms that thrive under certain
environmental conditions. Their proliferation is typically caused by the transport of
animal or human fecal wastes from the watershed. Water, containing excessive
bacteria and viruses can alter the aquatic habitat and create a harmful environment
for humans and aquatic life. Also, the decomposition of excess organic waste
causes increased growth of undesirable organisms in the water.
3.8 - Pesticides
Pesticides (including herbicides) are chemical compounds commonly used to control
nuisance growth or prevalence of organisms. Excessive application of a pesticide
may result in runoff containing toxic levels of its active component.
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La Costa Greens Neighborhood 1.09
Storm Water Management Plan
CHAPTER 4 - CONDITIONS OF CONCERN
4.1 - Receiving Watershed Descriptions
As shown in the watershed map on the following page, the pre-developed La Costa
Greens Neighborhoods 1.09 site drains to an unnamed tributary of San Marcos
Creek which eventually discharges to the Batiquitos Lagoon within the San Marcos
Creek watershed.
Development ofthe site will not cause any diversion to or from the existing
watershed to the storm drain system.
The Regional Water Quality Control Board has identified San Marcos Creek as part
ofthe Carlsbad Hydrologic Unit, San Marcos Creek Watershed, and the Batiquitos
Hydrologic Subarea (basin number 4.51).
4.2 - Pollutants of Concern in Receiving Watersheds
San Marcos Creek is not 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 forthe Batiquitos Lagoon and San Marcos Creek includes
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 ofthe San Marcos hydrologic area.
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WATEHSHED MAP FOR
LA COSTA GREENS
NEIGHBORHOOD 1.09
cmr OF CARLSBAD, CALIFORNIA
26 Los Monos HSA
(904.31) Agua Hedionda
Lagoon
Bacterial
Indicators^ 6.8 acres 1998
Sedimentation /
Siltation
27 Los Monos HSA
(904.31) Agua Hedionda
Creek lower portion Total Dissolved
Solids lower 7 miles 2002
28 San Marcos HA
(904.50)
Pacific Ocean
Shoreline at Moonlight State Beach Bacterial
Indicators^ 0.4 miles 1998
29 Escondido Creek
HA (904.60)
Pacific Ocean
Shoreline at San Elijo Lagoon Bacterial
Indicators^ 0.44 miles 1998
30 San Elijo HSA
(904.61)
San Elijo
Lagoon
Bacterial
Indicators^ 150 acres 1998
Eutrophic 330 acres
Sedimentation /
Siltation 150 acres
31 San Dieguito HU
(905.00)
Pacific Ocean
Shoreline at San Dieguito Lagoon Mouth Bacterial
Indicators^ 0.86 miles 1998
32 Del Dios HSA
(905.21 and
905.22)
Green Valley
Creek Sulfate 1 mile 2002
33 Del Dios HSA Hodges Entire Reservoir Color Entire 2002
(905.21) Reservoir Entire Reservoir Nitrogen
Phosphorus
Total Dissolved
Solids
Reservoir
(1104 acres)
34 Felicita HSA
(905.23) Felicita Creek Total Dissolved
Solids
lower 0.92
miles 2002
35 Felicita HSA
(905.23) Kit Carson
Creek should in 905.21 HSA Total Dissolved
Solids 1 mile 2002
36 Highland HSA
(905.32) Cloverdale
Creek
Phosphoms
Total Dissolved
Solids
1.2 miles 2002
37 Sutherland HSA
(905.53)
Sutherland
Reservoir Entire Reservoir Color Entire
Reservoir 2002
38 Miramar Reservoir
HA (906.10)
Los
Penasquitos
Lagoon
Entire Lagoon Sedimentation /
Siltation 469 acres 1998
39 Miramar Reservoir
HA (906.10)
Pacific Ocean
Shoreline
Torrey Pines State Beach at Del
Mar (Anderson Canyon)
Bacterial
Indicators^ 0.4 miles 2002
40 Scripps HA
(906.30) Pacific Ocean
La Jolla Shores Beach at El Paseo
Grande Bacterial 3.9 miles 1998 40 Scripps HA
(906.30)
Shoreline La Jolla Shores Beach at Caminito
Del Oro
• Indicators^
La Jolla Shores Beach at
Vallecitos
La Jolla Shores Beach at Ave de la
Playa
last updated 9/23/2003
S:\WQS\303dllst\SD Staff Report-2002\FINAL VERSIONS\Listed Waterbodies-2002j{ls\Table 4 (Sep03 page 3 of 6
Table 2-2. BENEFICIAL USES OF INLAND SURFACE WATERS
1,2
Inland Surface Waters . Hydrologic Unit
Basin Number
BENEFICIAL USE
1,2
Inland Surface Waters . Hydrologic Unit
Basin Number
M
U
N
A
G
R
1
N
D
P
R
0
C
G
W
R
F
R
S
H
P
0
W
R
E
C
1
R
E
C
2
B
1
0
L
W
A
R
M
0
0
L
D
W
1
L
D
R
A
R
E
S
P
W
N
San Diego County Coastal Streams - continued
Buena Visla Lagoon 4.21 See Coastal Waters- Table 2-3
Buena Vlsta Creek 4.22 + • • • • • i •
Buena Vista Creek • 4.21 + • • • • • • •
Agua Hedionda 4.31 See Coastal Waters- Table 2-3
Agua Hedionda Greek 4.32 • • • • • • •
Buena Creek 4.32 • • • • • • •
Agua Hedionda Creek 4.31 • • • • • • •
Letterbox canyon 4.31 • • • • • • •
Canyon de las Encinas 4.40 + o • • •
San IViarcos Creel? Watershed
Batiquitos Lagoon 4.51 See Coastal Waters- Table 2-3
San Marcos Creek 4.52 + • • • • •
unnamed Intermittent streams 4.53 + • • • • •
San IViarcos Creek Watershed
San IViarcos Creek 4.51 + • • • • •
Encinitas Creek 4.51 + • • • • •
• Existing Beneficial Use
0 Potential Beneficial Use
+ Excepted From MUN (See Text)
1 Waterbodies are listed multiple times if they cross hydrologic area or sub area boundaries.
Benefidal use designations apply to all tributaries to the indicated waterbody, if not listed separately.
Tablo 2-2
BENEFICIAL USES 2-27
March 12, 1997
Table 2-3. BENEFICIAL USES OF COASTAL WATERS
BENEFICIAL USE
Coastal Waters Hydrologic
Unit Basin
1
N
N
A
R
E
R
E
C
.0
B
1
E
S
W
I
R
A
M
A
A
Q
M
1
S
P
W
A
S
H
Number D V C C M 0 T L R R U G W R E Number 1 2 M L D E A R N M L
L
Pacific Ocean • • • • • • • • • • • • •
Dana Point Harbor • • • • • • • • •
Del Mar Boat Basin • • • • • • • • • •
Mission Bay • • • • • • • • • • •
Oceanside Harbor • • • • • • • • • • •
San Diego Bay ' • • • • • • • • • • • •
Coastal Lagoons
Tijuana River Estuary ii.ii • • • • • • • • • • •
Mouth of San Diego River 7.11 • • • • • • • • • •
Los Penasquitos Lagoon ^ 6.10 • • • • • • • • • •
San Dieguito Lagoon 5.11 • • • • • • • • •
Batiquitos. Lagoon 4,51 • • • • • • • • •
San Elijo Lagoon . 5.61 • • • • • • • • •
Aqua Hedionda Lagoon 4.31 • • • • • • • • • • •
^ Includes the tidal prisms of the Otay and Sweetwater Rivers.
2 Fishing from shore or boat permitted, but other water contact recreational (REC-1) uses are prohibited.
9 Existing Beneficial Use
Tabla 2-3 '
BENEFICIAL USES ' 2-47
March 12, 1997
Table 3-3. WATER QUALITY OBJECTIVES
Concentrations not to be exceeded more than 10% of the time during any one year period.
Ground Water Hydrologic
Basin Unit
Number
Constituent (mg/L or as noted)
TDS CI SO4 %Na NO3 Fe Mn MBAS ODOR Turb
NTU
Color
Units
Buena Vista Creek HA 4.20
El Salto HSA a 4.21 3500 800 500 60 45 0.3 0.05 0.5 2.0 none 15 1.0
Vlsta HSA a 4.22 1000 b 400 b 500 b 60 10 b 0.3 b 0.05 b 0.5 0.75 b 15 1.0
Agua Hedionda HA 4.30 1200 500 500 60 10 0.3 0.05 0.5 0.75
Los Monos HSA aj 4.31 3500 800 500 60 45 0.3 0.05 0.5 2.a none
15
15
1.0
1.0
Encinas HA 4.40 3500 b 800 b 500 b 60 45 b 0.3 b 0.05 b 0.5 2.0 b none 15
San Marcos HA 4.50 1000 400 500 60 10 0.3 0.05 0.5 0.75 none 15
1.0
1.0
Batiquitos HSA aek 4.51 3500 800 500 60 45 0.3 0.05 0.5 2.0 none 15
Escondido Creek HA a 4.60 750 300 300 60 10 0.3 0.05 0.5 0.75 none 15
1.0
1.0
San Elijo HSA a 4.61 2800 700 600 60 45 0.3 0.05 0.5 1.0 15 1.0
Escondido HSA 4.62 1000 300 400 60 10 0.3 0.05. 0.5 0.75 15 1.0
SAN DIEGUITO HYDROLOGIC UNIT 905.00
Solana Beach HA a
Hodges HA
5,10
5.20
1500 b
1000 b
500 b
400 b
500 b
500 b
60
60
46 b
10 b
0.85 b
0.3 b
0.15 b
0.05 b
0.5
0.5
0.75 b
0.75 b
15
15
1.0
1.0
San Pasqual HA 5.30 1000 b 400 b 500 b 60 10 b 0.3 b 0.05 b 0.5 0.75 b none 15
Santa Maria Valley HA 5.40 1000 400 500 60 10 0.3 0.05 0.5 0.75 none 15
1.0
1.0
Santa Ysabel HA 5.50 500 250 250 60 0.3 0.05 0.5 0.75 none 15 1.0
PENASQUITOS HYDROLOGIC UNIT 906.00
Miramar Reservoir HA af 6.10 1200 500 500 60 10 0.3 0.05 0.5 0.75 none 15 1.0
Poway HA 6.20 750 q 300 300 60 10 0.3 0.05 0.5 0.75 none 15 1.0
Scripps HA 6.30
Miramar HA g 6.40 750 300 300 60 10 0,3 0.05 0.5 0.75 none 15
Tecolote HA 6.50
1.0
HA - Hydrologic Area
HSA - Hydrologic Sub Area (Lower casa letters Indicate endnotes following the table,)
Table 3-3
WATER QUALITY OBJECTIVES Paga 3-29 October 13, 1994
La Costa Greens Neighborhood 1.09
Storm Water Management Plan
Chapter 5 - FLOW-BASED BMPs
5.1 - 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 vortex effects) or non-mechanical
devices (based on weir hydraulics and specially designed filters) to promote settling
and removal of pollutants from the runoff.
Per the request of the City of Carlsbad, 85'*^ percentile flow calculations were
performed using the Rational Method. The basic Rational Method runoff procedure
is as follows:
Design flow (Q) = C * I * A
Runoff Coefficient (C) - In accordance with the City of Carlsbad 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 ofthe 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
surface, 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.
5.2 - Vortechs Treatment Units
The Vortechs Storm Water Treatment System is designed to efficiently remove grit,
contaminated sediments, metals, hydrocarbons and floating contaminants from
surface runoff. Combining swirl-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.
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La Costa Greens Neighborhood 1.09
Storm Water Management Plan
Other features ofthe Vortechs Systems include the following:
Large capacity system provides an 80 percent net annual Total
Suspended Solids (TSS) removal 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 offline
configuration
The tangential inlet to the system creates a swirling motion that directs settleable
solids into a pile towards the center ofthe grit chamber. Sediment is caught in the
swirling 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.
5.3 - Pollutant Removal Efficiencv Table
Pollutant of Concern BMP Categories
Hydrodynamic
Separation
Devices'^^
Vortechs
Stormwater- ,
Treatment System .
Sediment M-H • --.-"^ H. .r;f •
Nutrients L-M L-M
Heavy Metals L-M -•-/^.-CL-M*c-.. - .
Organic Compounds L-M -.-^.BL-M- - - --f-
Trash & Debris M-H . ••.:1-:H--V.- - "
Oxygen Demanding Substances L
Bacteria L ' L - ->
Oil & Grease L-H H
Pesticides L L
(1) The County will periodically assess the performance characteristics ofthese BMPs to
update this table.
(2) Proprietary Structural BMPs. Not ali 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 of Nonpoint Pollution in
Coastai Waters (1993), National Stormwater Best Management Practices Database (2001),
and Guide for BMP Selection in Urban Developed Areas (2001).
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La Costa Greens Neighborhood 1.09
Storm Water Management Plan
5.4 - Maintenance Reguirements
Flow-based storm water treatment devices should be inspected periodically to
assure their condition to treat anticipated runoff. Maintenance ofthe proposed
Vortechnics units includes inspection and maintenance 1 to 4 times per year.
Maintenance of the Vortechs units involves the use of a "vactor truck", which clears
the grit chamber ofthe 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 ofthe treatment unit. Properly 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 properly 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 ofthe unit.
5.5 - Schedule of Maintenance Activities
Target Maintenance Date - March 15'*^
Maintenance Activity - Annual inspection and cleanout. Clear grit chamber of each
unit with vactor truck. Perform visual inspection. Remove floatables.
5.6 - Annual Operations & Maintenance Costs
The following costs are intended only to provide a magnitude ofthe costs involved in
maintaining BMPs. Funding shall be provided by the Master Home Owners
Association for La Costa Greens, of which neighborhood 1.09 is a member of.
Approximate annual maintenance costs for each ofthe proposed Vortechs units are
outlined below. Costs assume a 3 man crew:
Maintenance for Model PCI 6x24:
Periodic Inspection, Maintenance and Monitoring = $800
Annual Cleanout Cost = $3,000
Subtotal = $3,800
Contingency = $380
Total = $4,180
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La Costa Greens Neighborhood 1.09
.storm Water Management Pian
CHAPTER 6 - SOURCE CONTROL BMPS
6.1 - 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, pruning, 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 construction-related wastes.
6.2 - Urban Housekeeping
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 ofthese potential storm 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.).
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La Costa Greens Neighborhood 1.09
Storm Water Management Plan
6.3 - 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 ofthese potential storm 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.
6.4 - Site Design BMPs
Prionty projects, such as the La Costa Greens Neighborhood 1.09 development,
shall be designed to minimize, to the maximum extent practicable the introduction of
pollutants and conditions of concern that may result in significant impact, generated
from site runoff to the storm water conveyance system. Site design components can
significantly reduce the impact of a project on the environment. The following design
techniques have been proposed to accomplish this goal.
- Implementing on-lot hydrologically functional landscape design and
management practices; Additional detail regarding landscaping design is
discussed in section 6.1.
- Minimizing project's impervious footprint. Methods of accomplishing this goal
include constructing streets, sidewalks, and parking lots to the minimum
widths necessary without compromising public safety. Another method for
minimizing impervious area includes incorporating landscaped areas in the
drainage system to encourage infiltration and reduce the amount of directly
connected impervious areas.
- Minimizing directly connected Impervious Areas. Where landscaping is
proposed, drain rooftops into adjacent landscaping prior to discharging to the
storm water conveyance system.
Approximately 30% ofthe Neighborhood 1.09 proposed project site will remain
undeveloped.
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La Costa Greens Neighborhood 1.09
Storm Water Management Plan
CHAPTER 7 - SITE BMP DESIGN
VORTECHS TREATMENT UNITS
7.1 - BMP Locations
The site design includes a single Vortechs treatment unit (shown on BMP Location
Map located on the following page). The proposed Vortechs Model PCI6x24 will be
located offline from the main storm drain system and is to be located in the vicinity of
the Street KK cul-de-sac.
7.2 - Determination of Design Treatment Flows
The 85"^ percentile design flow rate has been calculated using the Rational Method.
Required data forthe Rational Method treatment flow determination include the
following:
- Runoff Coefficient (C) = 0.53
- Rainfall Intensity (I) = 0.20 inches per hour
- Drainage area to treatment unit (A) = 291.5 Ac.
Runoff coefficients were derived based upon a weighted average of each area
tributary to the treatment unit and the associated runoff coefficient.
The following table summarizes the parameters used for determination of design
flows to each ofthe Vortechs treatment units.
DESIGN RUNOFF DETERMINATION SUMMARY TABLE
Treatment Unit
Runoff
Coefficient
(C)
85^"
Percentile
Rainfall
(inches/hour)
Drainage
Area
(acres)
85'^ Pet.
Design Flow
(cfs)
PC 16x24 0.53 0.2 291.5 30.9
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La Costa Greens Neighborhood 1.09
Storm Water Management Plan
7.3 - Vortechs Treatment Unit Selection
Per the special design prepared by Scott Gorneau of Vortechnics, (excerpts
attached dated August 15, 2003) the Vortechs Model PCI6x24 has been designed
to treat a flow rate of 52.82 cfs. This unit (details attached), as proposed on the
improvement plans, is an offline precast treatment unit, meaning that the design flow
rate is forced into the treatment area through a diversion structure, while flows in
excess ofthe design flow rate pass over an inline weir and proceed downstream.
The weir in the diversion structure will create a restriction, which will raise the HGL
upstream of the weir. These losses will be analyzed in the Hydrology study to
ensure that the potential for flooding occurrences during high return rainfall events is
minimized to an acceptable level.
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VILLAGES OF LA COSTA
NEIGHBORHODD 1.09, 1.10 AND PORTION OF 1.12 (NORTH)
TDCAT^/I^MT Cl n\A; r^CTCOR/lIM A-TI^M.
Q=C*I*A
TREATMENT AREA 291.50 ACRES
RAINFALL INTENSITY 0.20 IN/HR
WEIGHTED CURVE NUMBER 0.53
Q = 30.90 CFS
4:16 PM6/9/2003 Sheetl RM-TREATMENT FLOW.xIs
Plan View
GritChamber Oil Chamber/. FlowCantrol Baffle Wall: . • Chamber
• ••••:• Elevation View: Dry-Weather
Grit Chamber
The swirling motion created by the
tangential inlet directs settleable
solids toward the center of this
chamber. Sediment is caught in
the swirling flow path arid settles •'
back onto the pile after the storm
•event: is oven - • ..
Oil Chamber & Baffle Wall •
The center baffle traps floatables in
•the oil chamber, even during clean^
.out. Highly resistaritto flpw.surges.
Flow Control Chamber ^
.•The weir and orifica flow control'sf^'•"•
" -1] Raise level and volume in the.'r-''
^sterh as flow rate increases;' arici*:
SJ gradually drain the.'system as'^
flow rate subsides.' .' , '•
1) Initial Wet Weather Phase
During a two-month storm event tha water level begins to
• rise above the top of the inlet pipe. This influent control
feature reduces turbulence and avoids resuspension
of pollutants.
3) Full Capacity Phase
When the high-flow outlet approaches fuil discharge, stonn
drains are flawing st peak capacitj/t The Vorta±is Systsm is
designed to match your design storm flow and provide treat-
2) Transition Phase
As the inflow rate increases above tha controlled outflow
rate, the tank fills and the floating contaminant layer accu-
mulated from past storms rises. Swirling action increases
at this stage, while sediment pile remains stable.
—I—'•^—
4) Storm Subsidence Phase/Cleaning
Treated runoff is decanted at a contralled rate, restoring the
water level to a low dryweatiier vdume and revealing a cnnicai
pile of sediment The low water levei iaciiitates inspection and
^ ~r the WortecM' Stormwater Treatment System
Perfcrated Covers
iiw.i
J L
=1 /
8' ta 9' ^ -/
Typ'cal
ffta 4'
. 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
fax or man the worksheet to
Vortechnics with your site plan,
and we'll produce detailed
Vortechs System scale draw-
ings free of charge.
Bevation View
Engineering NdCES ' .
S^h^^S^,™» S^'"K * ^ "^^^ °" prmiiding one square foot of grie-'
chancer surferaaraafDP each TOO gpm of peal, design storm flow rate (e.g.. lO-yeap storm). For more ••• • .
.dataHs aboue Vbrtediraca ^•ngcritsria refer .to Vbrtailinica Tachnical Bulleth 3;. • • • • • •: ' • •
,B) Sadiment storagayoluiiys assiTOBs.a.3 fboesump.. . " ' . , I " '
y2,S^!^Mf,^J^v^T^''t^^^ ^P*""" aPpScatfon. An^'alterations to iha'sildng chart specifi-'
:;^^^^'^^^S^^Tr^':T:^'^ ahop drawinga. Pbaaa-call Vortachnica for tha Vsht of spe..
rapaci6y.>han itknaadid to.;maU-a spedRc'faquirim'ent fc'r spiil containment.'can be': ^^Thn ™1""-«"^"?-™'JTtha selected modeL Vortachnica tachnical staff will optimia System' • ^ gec»Tie07to.ma8t containment raquiramenta withm
l.MetnbSpsa'ffcaton'Oiart • . •
Vortechs System Inlet/Outlet Configurations
Vortechs Systems con be configured to accommo-
date various inlet and outlet pipe orientatLons.
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 \ Side Inlet
t Offline I
Ta
Palish
\ Pppfppat:rnpnt: Ta
Vortechs ™ Stormwater Treatment Systems
Vortechnics
FLOW CALCULATIONS
La Costa Greens Village Neighborhood
Carlsbad, CA
PCI6X24
System 1.10
Vortechs Orifice
Cd 0.56
9.00
Crest Elevation (ft) = 99.50
A (ft')
Vortechs Weir
Cd = 0
Weir Crest Length (ft) = 0
Crest Elevation (ft) = 104.00
Bypass Weir
Cd = 3.3
Weir Crest Length (ft) = 11
Crest Elevation (ft) = 101
Head Elevation Orifice Flow Weir Flow Bypass Flow Total Flow
(ft) (ft) (cfs) (cfs) (cfs) (cfs)
0.00 99.50 0.00 0.00 0.00 0.00
0.25 99.75 1.69 0.00 0.00 1.69
0.50 100.00 4.77 0.00 0.00 4.77
0.75 100.25 8.76 0.00 0.00 8.76
1.00 100.50 13.48 0.00 0.00 13.48
1.25 100.75 18.84 0.00 0.00 18.84
1 50 101 00 24.76 0 00 0 00 24.76
1.75 101.25 31.21 0.00 4.54 35.74
2.00 101.50 38.13 0.00 12.83 50.96
2.25 101.75 45.21 0.00 23.58 68.78
2 50 102.00 49.52 0 00 36 30 85.82
First highlighted row indicates treatment of the 85th percentile flow (first flush) before bypass flow occurs. Second row
indicates the elevation at which the 24 inch inlet pipe is submerged and thereby acting as the flow control into the unit,
Flows greater than the 24 inch pipe capacity will most likely be bypassed.
ICalculated by: WSG 10/10/2003 jjChecked by:
104 5 -
104 0 -
103 5 -
103 0 -
102 5 -
102 0
101 5 -
101 0 -
100 5
100 0 -
99 5 -
99 0 •
Vortechs™ System
Stage Discharge Curve
Pi/m"** r*rr
0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0
Discharge (cfs)
f:\data\vortechn\projects\4404ADSPC16X24.xls AP 10/10/2003
Vortechs™ Stormwater Treatment Systems
VQRTECHS SYSTEM ESTIMATED NET ANNUAL TSS REMOVAL EFFICIENCY
Vortechnics La Costa Greens Village Neighborhood
Carlsbad, CA
PCI 6X24
System 1.10
Design Ratio^ =
(193.5 acres) x (0.53) x (449 qpm/cfs)
(201.1 sf) = 228.9
Bypass occurs at an elevation of 101' (at approximately 55 gpm/sf)
Rainfall Intensity Ooeratinq Rate^ % Total Rainfall Rmvl. Effcv" Rel. Effcy
•7hr gpm/sf Volume^ (%) (%)
0.02 4.6 10.4% 98.0% 10.2%
0.04 9.2 10.1% 98.0% 9.9%
0.06 13.7 9.7% 98.0% 9.6%
0.08 18.3 8.1% 98.0% 8.0%
0.10 22.9 8.2% 98.0% 8.0%
0.12 27.5 8.6% 98.0% 8.4%
0.14 32.0 4.6% 98.0% 4.5%
0.16 36.6 4.9% 97.5% 4.7%
0.18 41.2 5.2% 96.0% 5.0%
0.20 45.8 3.6% 94.0% 3.4%
0.25 56.9 9.0% 89.0% 8.0%
0.30 64.6 5.3% 83.0% 4.4%
0.35 70.3 2.8% 78.5% 2.2%
0.40 76.1 2.7% 73.5% 2.0%
0.45 81.1 2.0% 69.0% 1.4%
0.50 85.5 0.0% 65.0% 0.0%
0.60 97.1 0.4% 52.0% 0.2%
0.70 103.4 1.6% 0.0% 0.0%
89.8%
% rain falling at >0.7'7hr or bypassing treatment =
Assumed removal efficiency for bypassed flows =
Removal Efficiency Adjustment =
Net Annual TSS Removal Efficiency =
2.9%
0.0%
7.6%
82%
1 - Design Ratio = (Total Drainage Area) x (Runoff Coefflcient) x (cfs to gpm conversion) / Grit Chamber Area
- The Total Drainage Area and Runoff Coefficient is specified by the site engineer.
- The conversion factor from cfs to gpm is 449.
• Operating Rate (gpm/sf) = intensity (7hr) x Design Ratio.
3 - Based 10 Years of Hourly Precipitation Data From NCDC Station 7740, San Dlego WSO Airport, San Diego County, CA
4 - Based on Vortechnics laboratory verified removal of 250 micron particles (see Technical Bulletin #1).
5- Reduction due to use of 60-minute data for a site that has a time of concentration less than 30-minutes.
ICalculated by: WSG 10/10/2003 "llChecked byT
f:\data\vortechn\projects\4404ADSPC16X24.xls AP 10/10/2003
La Costa Greens Neighborhood 1.09
Storm Water IVIanagement Plan
CHAPTER 8 - REFERENCES
"Standard Urban Storm Water Mitigation Plan - Storm Water Standards", City of
Carlsbad, April 2003.
"Standards for Design and Construction of Public Works Improvements in the City of
Carisbad", City of Carlsbad, California; April 1993.
"Master Drainage and Storm Water Quality Management Plan", City of Carlsbad,
California; March 1994.
"Tentative Map Drainage Study for La Costa Greens - Phasel Neighborhoods 1.08
through 1.14," Hunsaker & Associates San Diego, Inc. April 17, 2003.
"Hydrology & Hydraulic Study- La Costa Greens Phase 1", O'Day Consultants; May
25, 2002
"Hydrology Manual", County of San Diego Department of Public Works - Flood
Control Division; Updated April 1993.
"San Diego County Hydrology Manual", County of San Diego Department of Public
Works - Flood Control Section; June 2003.
"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 ofthe 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.
'Wafer Quality Pian for the San Diego Basin", California Regional Water Quality
Control Board - San Diego Region, September 8, 1994.
"Vortechnics Storm Water Treatment System Manual", Vortechnics; Revised May
2000.
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0 2000 4000 6000
SCALE l'=2000'
HUNSAKER
&. ASSOCLVTES
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QUADRANGLE MAP WATERSHED
EXHIBIT FOR
LA COSTA GREENS
CARLSBAD. CALIFORNIA
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