HomeMy WebLinkAboutPUD 02-11A; LA COSTA GREENS; STORM WATER MANAGEMENT PLAN; 2004-08-27City of Carlsbad, California
Prepared for:
Real Estate Collateral Management Company
do Morrow Development
1903 Wright Place, Suite 180
Carlsbad, CA 92008
W.O. 2352-96
March 12, 2004
Amended August 27, 2004
Hunsaker & Associates
San Diego, Inc. oFESS,
No. 48670
* Exp. 06/30/06 *
Tice President
PUW O -11LA--
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LI' HUNSAKER
&ASSOC[ATES
- '- S A N D I E C 0, I N C.
PLANNING
ENGINEERING
SURVEYING
STORM WATER
IRVINE
LOS ANGELES MANAGEMENT PLAN
RIVERSIDE for SAN DIEGO LA COSTA GREENS
RECREATION CENTER
DAVE HAMMAR
LEX WILLIMAN
ALISA VIALPANDO
DAN SMITH
RAY MARTIN
10179 Huennekens St.
San Diego CA 92121
(858) 558-4500 PH
(858) 558-1414 FX
www.HunsakerSD.com
Info@HunsakerSD.com
La Costa Greens - Recreation Center
Storm Water Management Plan
TABLE OF CONTENTS
CHAPTER 1 - Executive Summary
1.1 Introduction
1.2 Summary of Proposed Development
1.3 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 Concern in Receiving Watersheds
4.3 Peak Flow Attenuation (Regional Detention Facility)
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 Schedule of Maintenance Activities
5.6 Annual Operations and Maintenance Costs
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La Costa Greens - Recreation Center
Storm Water Management Plan
CHAPTER 6— Source Control BMPs
6.1 Landscaping
6.2 Urban Housekeeping
6.3 Automobile Use
6.4 Site Design
I CHAPTER 7— Site BMP Design (Vortechs Treatment Units)
7.1 BMP Location
7.2 Determination of Treatment Flow
7.3 Vortechs Treatment Unit Selection
I CHAPTER 8— Fiscal Resources
8.1 Fiscal Mechanism Selection
8.2 Agreements (Mechanisms to Assure Maintenance)
CHAPTER 9 - References
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List of Tables and Figures
Chapter 1 -Watershed Map
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Chapter 1 - BMP Location Map
Chapter 2 - Storm Water Applicability Checklist
Chapter 3 - Pollutant Category Table
Chapter 4 - San Diego Region Hydrologic Divisions
I Chapter 4 - Combined 1998 and Draft 2002 Section 303(d) Update
Chapter 4 - Beneficial Uses of Inland Surface Waters
Chapter 4 - Water Quality Objectives I Chapter 5 - Pollutant Removal Efficiency Table (Flow-Based BMPs)
Chapter 7 - 85th Percentile Rainfall Isopluvial Map
Chapter 7 - Neighborhood 1.10 BMP Location Map I Chapter 7 - Design Runoff Determination Summary Table
Chapter 7 - Vortechs Unit Treatment Capacity Table
Chapter 7 - Vortechs System Data
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La Costa Greens - Recreation Center
I Storm Water Management Plan
Chapter 1 - EXECUTIVE SUMMARY
I
1.1 - Introduction
I The La Costa Greens Recreation Center project site is located at the intersection of
Lapis Road and Amber Lane, north of Alga Road, south of the proposed extension
I of Poinsettia Lane, west of Alicante Road, within Neighborhood 1.12 of the La Costa
Greens Development. Neighborhood 1.12 is one of seven subdivisions within the La
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Costa Greens Phase I development. See the Vicinity Map below.
Per the City of Carlsbad SUSMP, the La Costa Greens Recreation Center project is
classified as a Priority Project and subject to the City's Permanent Storm Water BMP
Requirements.
I 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
I the Regional Water Quality Control Board's Order No. 2001-01, and the City of
Carlsbad SUSMP.
I This SWMP recommends the location and sizing of site Best Management Practices
(BMPs) which include one Vortechs treatment unit (see BMP Location Map in this
chapter).
I Furthermore, this report determines anticipated project pollutants, pollutants of
concern in the receiving watershed, peak flow mitigation, recommended source
I control BMPs, and methodology used for the design of flow-based and volume-
based BMPs.
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LA COSTA GREENS VICINITY MAP
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La Costa Greens - Recreation Center
Storm Water Management Plan
1.2— Summary of Proposed Development
The proposed La Costa Greens Recreation Center will consist of amenities such
as a communal swimming pool, an assembly hall, footpaths and a water
monument with associated waterfall. The site drains via an area drain system to
the south west of the site, draining to the existing storm drain located in Lapis
Road.
Runoff from the Recreation Center (located in the northern segment of
Neighborhood 1.12) will drain to a proposed storm drain outlet located at the
southwest corner of Neighborhood 1.10 (at the Tanzanite Drive cul-de-sac). This
runoff discharges from the storm drain to the unnamed tributary of San Marcos
Creek, which flows in a southerly direction along the west side of Neighborhood'
1.10. Runoff from Neighborhood 1.09, Neighborhood 1. 10, and the adjacent
residential development east of La Costa Greens Phase I will also drain to this
storm drain outlet location.
The offsite developed areas, which will drain to the storm drain outlet located in
Neighborhood 1.10 and 1.14 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 acres of area; and one at the northeast corner of Neighborhood
1.12 consisting of 79 acres of area.
Neighborhood 1.12 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 36 residences. The proposed project site
consists of 36 residential lots and 5 open space lots, for a total area of 23.50 acres
(12.19 acres and 11.32 acres respectively). Approximately 48% will remain
undeveloped.
1.3— Results and Recommendations
Storm water from the proposed Recreation Center (and also the northern segment of
Neighborhood 1.12) will be treated via a treatment unit located at the southwest
corner of Neighborhood 1.10 (at the TanzaniteDrive cul-de-sac). Prior to discharge
into the storm drain system in Alga Road, all storm water will pass though a
proposed diversion structure that will divert the entire 85th percentile flow into the
proposed storm water treatment unit. Flows in excess of the treatment flow will
bypass the treatment unit. The analysis performed in this report indicates that a
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LEGEND LA COSTA GREENS
WATERSHED TRIBUTARY POST-CONSTRUCTION
TO TREATMENT UNIT BMP LOCATION EXHIBIT
WATERSHED TRIBUTARY
TOTRATMENTUNIT
r '
FLOW-BASED BMP FOR
NEIGHBORHOOD 1.08
AND ALICANTE ROAD
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L 077 2 - -
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1.10, AND PORTION OF 1.112
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'p. . ..' 'T.
FLO-BASED BMP FOR 0 o 0 0 o
NEIGj-IBORHOOD 1.11
If 'S
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FLOW-BASED BMP FOR
NEIGHBORHOOD 1.13, 1.14,
PORTION OF 112,
AND ALICANTE ROAD I'M kagggm
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La Costa Greens - Recreation Center
I Storm Water Management Plan
Vortechs Model PC16x24 will be required to meet the water quality treatment
I requirements for the northern portion of Neighborhood 1.12. The proposed Vortechs
Model PC16x24 will be located offline from the main storm drain system and is
proposed to be located in the vicinity of the Tanzanite Drive cul-de-sac.
I In addition to the primary treatment facilitated by the proposed Vortechs Model
PC16x24, storm water treatment in excess of the Regional Water Quality Control
I Board requirements will be provided downstream of the storm drain ouffall. After
discharge storm water from the northern portion of Neighborhood 1.12 will drain
through an existing vegetated constructed channel en route to the Alga Road
I culverts. This vegetated channel will provide additional treatment for 85th percentile
I Since primary and additional treatment will be provided, a volume-based BMP will
not be required. Maintenance of Vortechs units, which will be the responsibility of the
Master Homeowners Association, is addressed in Chapter 8 of this report.
I The report replaces any post-construction BMP text included in the Preliminary
SWPPP prepared along with the Master Tentative Map. SWPPP reports are typically
I required for storm water pollution prevention during interim construction activities.
Desiltation basins previously designed for this project were intended only to collect
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sediment during the construction phase of the project and were not intended to be
permanent facilities. This report specifies post-construction condition BMP treatment
controls.
Anticipated pollutants of concern are included in Chapter 3 of this report. Tables
included in Chapter 7 show that the proposed Vortechs system adequately treats the
anticipated pollutants of concern to a degree previously determined acceptable by
I the Regional Water Quality Control Board. Treatment BMPs recommended for the
project site are based on 85th percentile design flow calculations and are not based
quantitative pollutant loading analysis. Previous attempts to apply quantitative
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methods for estimating pollutant loading and removal efficiencies, such as in the
1993 Municipal Handbook, are no longer considered accurate for southern
California.
Chapter 6 presents a listing of recommended non-structural source control BMPs,
I which include landscaping, urban housekeeping, etc.
85th percentile calculations included in this report were generated using the Rational
I Method. This method calculates the resultant 85th percentile flow rate based upon a
peak rainfall intensity of 0.2 inches per hour. This is consistent with criteria set forth
in the "Model Standard Urban Storm Water Management Plan for San Diego
I County, Port of San Diego, and Cities in San-Diego County,"
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flow (by reducing the flow velocities in the channel and in turn settling out pollutants).
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La Costa Greens - Recreation Center
Storm Water Management Plan
Chapter 2— STORM WATER CRITERIA
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2.1 - Regional Water Quality Control Board Criteria
I 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.
I .. 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
I 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 I treatment controls that keep soil and other pollutants onsite once they have been
loosened by storm water erosion.
I 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
I 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.
I All structural BMPs shall be located to infiltrate, filter, or treat the required runoff
volume or flow (based on the 85th percentile rainfall) prior to its discharge to any
I receiving watercourse supporting beneficial uses.
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2.2 - City of Carlsbad SUSMP Criteria
Per the City of Carlsbad SUSMP, the La Costa Greens project is classified as a
Priority Project and subject to the City's Permanent Storm Water BMP
I 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
4/03103
Part B: Determine Standard Permanent Storm Wtnr Rnniirmni'
Does the project propose:
No- New impervious areas, such as rooftops, roads, parking lots, driveways, paths and sidewalks?
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New pervious landscape areas and irrigation systems?
Permanent structures within 100 feet of any natural water body?
Trash storage areas?
S. Liquid or solid material loading and unloading areas? V Vehicle or equipment fueling, washing, or maintenance areas?
Require a General NPDES Permit for Storm Water Discharges Associated with Industrial Activities (Except construction)?*
Commercial or Industrial waste handling or storage, excluding typical office or household waste? -
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Any grading or ground disturbance during construction?
Any new storm drains, or alteration to existing storm drains?
l_ *10 find out if your project is required to obtain an Individual General NPDES Per
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Discharges Associated with Industrial Activities, visit the State Water Resource
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at, www.swrcb.ca.gov/stormwtrllndustrial.htnd
Section 2. Construction Storm Water BMP Requirements:
If the answer to question I of Part C is answered 'Yes," your project is subject to Section IV, "Construction Storm Water BMP Performance Standard
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but the answer to any of the remaining questions is "Yes," your pr
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Section IV, "Construction Storm Water BMP Performance Standard
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a Water Pollution Control Plan (WPCP). If every question in Part C
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"NO" your project is exempt from any construction storm water BMP require
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the answers to the questions in Part C are "Yes,1 complete the construction site prioritization in Part D, below.
Pr+ ( eh-!vr1k1n Phs tnrm Witr Rpniiirpmnf
Would the project meet any of these criteria during construction?
Yes No Is the project subject to California's statewide General NPDES Permit fo
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Discharges Associated With Construction Activities?
- Does the project propose grading or soil disturbance?
- Would storm water or urban runoff have the potential to contact any portion of
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construction area, Including washing and staging areas?
- - Would the project use any construction materials that could negatively aff
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quality if discharged from the site (such as, paints, solvents, concrete, an
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stucco)?
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Storm Water Standards
4/03/03
Part D: Determine Construction Site Priority
In accordance with the Municipal Permit, each construction site with construction storm water BMP requirements must be designated with a priority: high, medium or low.
This prioritization must be completed with this form, noted on the plans, and included in the SWPPP or WPCP. Indicate the project's priority in one of the check boxes using the criteria below, and existing and surrounding conditions of the project, the type of
activities necessary to complete the construction and any other extenuating
circumstances that may posea threat to water quality. The City reserves the right to
adjust the priority of the projects both before and during construction. [Note:
The construction priority does NOT change construction BMP requirements that apply
to projects; all construction BMP requirements must be identified on a case-by-case
basis. The construction priority does affect the frequency of inspections that will be
conducted by City staff. See Section IV.1 for more details on construction BMP
requirements.]
r A) High Priority
Projects where the site is 50 acres or more and grading will occur during the
rainy season
Projects 5 acres or more. 3) Projects 5 acres or more within or directly
adjacent to or discharging directly to a coastal lagoon or other receiving water
within an environmentally sensitive area
Projects, active or inactive, adjacent or tributary to sensitive water bodies
B) Medium Priority
Capital Improvement Projects where grading occurs, however a Storm Water
Pollution Prevention Plan (SWPPP) is not required under the State General
Construction Permit (i.e., water and sewer replacement projects, intersection
and street re-alignments, widening, comfort stations, etc.)
Pen-nit projects in the public right-of-way where grading occurs, such as
installation of. sidewalk, substantial retaining walls, curb and gutter for an
entire street frontage, etc. , however SWPPPs are not required.
Permit projects on private property where grading permits are required,
however, Notice Of Intents (NOls) and SWPPPs are not required.
(3 C) Low Priority
Capital Projects where minimal to no grading occurs, such as signal light and
loop installations, street light installations, etc.
Permit projects in the public right-of-way where minimal to no grading occurs,
such as pedestrian ramps, driveway additions, small retaining walls, etc.
Permit projects on private property where grading permits are not required,
such as small retaining wails, single-family homes, small tenant
improvements, etc.
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La Costa Greens - Recreation Center
Storm Water Management Plan
Chapter 3—IDENTIFICATION OF TYPICAL POLLUTANTS
3.1 - Anticinated Pollutants from Project Site
The following table details typical anticipated and potential pollutants generated by
various land use types. The La Costa Greens Neighborhood 1.12 development and
the proposed Recreation Center will consist of detached single-family residences.
Thus, the Detached Residential Development category has been highlighted to
clearly illustrate which general pollutant categories are anticipated from the project
area.
General Pollutant Categories
Priority U) U)
to
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Project C >, U) Categories . E ° . E 2 °
Q co Z cijQ) X '-0 00 W i-0o )<Ci = 0 M > 0.
Detached
Residential X X X X X X X
Development
Attached
Residential X X x p(2) x
Development
Commercial
Development p( p( p(2) x p(5) x p(3) p(5)
>100,000 ft2
Automotive
Repair X X' X X
Shops
Restaurants X X X X
Hillside
Development X X X X X X
>5,000 ft2
Parking Lots p( p( x x p( x
Streets,
Highways & x p( x x x p(5) x
Freeways
Retail Gas x x x Outlets
X = anticipated
P = potential
A potential pollutant if landscaping exists on-site.
A potential pollutant if the project includes uncovered parking areas.
A potential pollutant if land use involves food or animal waste products.
Including petroleum hydrocarbons.
Including solvents.
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La Costa Greens - Recreation Center
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
I 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 I and possibly the development of septic conditions.
i 3.6 - Oil & Grease
Characterized as high high-molecular weight organic compounds. Primary sources
I 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
I quality. .. .- .-
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La Costa Greens - Recreation Center
Storm Water Management Plan
Chapter 4— CONDITIONS OF CONCERN
I 4.1 - Receiving Watershed Descriptions
I As shown in the watershed map on the following page, the pie-developed and
developed condition Recreation Center (and associated Neighborhood 1.12) site
drains to the Carlsbad watershed. In developed conditions, runoff from project site
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drains through the proposed storm drain systems and discharges into an unnamed
tributary of San Marcos Creek, and ultimately into the San Marcos Creek.
The Regional Water Quality Control Board has identified the San Marcos Creek as
part of the Carlsbad Hydrologic Unit (basin number 904.51).
I 4.2 - Pollutants of Concern in Receiving Watersheds
I The project location and watersheds have been compared to the current published
303(d) List of Water Quality Limited Segment, the nearest impaired water body is the
Pacific Ocean shoreline at Moonlight State Beach (basin number 904.50), impaired
I by bacterial indicators The Moonlight State Beach is roughly four (4) miles from the
project site.
I Table 3-2 from the "Water Quality Plan for the San Diego Basin" (also 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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Table 2-2. BENEFICIAL USES OF INLAND SURFACE WATERS
1,2
Inland Surface Waters Hydrologic Unit
BENEFICIAL USE M
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N
A
G
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0
P
R
0
C
G
W
R
F
R
S
H
P
0
W
R
E
C
1
R
E
C
2
B
I
0
L
A
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WC
MD
0
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0
R
A
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S
P
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N
San Diego County Coastal Streams - cdnt1hued
Buena Vista Lagoon 4.21 See Coastal Waters- Table 2-3
Buena Vista Creek 4.22 0 0 1 Buena Vista Creek 4.21 + ° *. I Agua Hedionda 4.31 See Coastal Waters- Table 2-3 Agua Hedionda Creek 4.32 * .
!Buena Creek 432 .
Agua Hedlondar Creek 431 . - . - - Letterbox canyon 4:31 •
Canyon do Isis Enclnas + 0 0 - - - San Marcos Creek Watershed
Bafiquitos Lagoon 4.51 See Coastal Waters- Table 2-3
San Marcos Creek 4.52 0 S 0 0
unnamed Intermittent streams 453 + I ....!.
San Marcos Creek Watershed
San Marcos Creek 4.51 + °
Enclnlas Creek 45j + • . •
Existing Beneficial Use 1 Waterbodies are listed multiple times if they cross hydrologic area or sub area boundaries.
0 Potential Beneficial Use 2 Beneficial use designations apply to all tributaries to the Indicated waterbody, If not listed separately.
+ Excepted From MUN (See Text)
Table 2-2
March 12, 1997 BENEFICIAL USES 2-27
26 Los Monos HSA
Agua Hedionda (904.31) Lagoon
Bacterial
Indicators 6.8 acres 1998
Sedimentation /
Siltation 27 Los Monos HSA
Agua Hedionda 'Total Dissolved (904.31) Creek lower portion
Solids lower 7 miles 2002
28 San Marcos HA Pacific Ocean at Moonlight State Beach BacterialE
0.4 miles 1998 (904.50) Shoreline Indicators
29 Escondido Creek Pacific Ocean at San Elijo Lagoon BacterialE
0.44 miles 1998 HA (904.60) Shoreline Indicators
30 San Elijo HSA San Elo Bacterial
IndicatorsE 150 acres 1998 (904.61) Lagoon
Eutrophic 330 acres
Sedimentation I 150 acres Siltation F Dieguito HU Pacific Ocean at San Dieguito Lagoon Mouth Bacterial 0.86 miles 1998 (905.00) Shoreline Indicator SE
32 Del Dios HSA
(905.21 and Green Valley
Sulfate I mile 2002 905.22) Creek
33 Del Dios HSA Hodges Ere Reservoir Color Entire 2002
Nitrogen (905.21) Reservoir Reservoir
.. Phosphorus (1104 acres)
Total Dissolved
Solids
34 Felicita HSA
Total Dissolved lower 0.92 (905.23) Felicita Creek
Solids miles 2002
35 Felicita HSA
(905.23) Kit Carson should in 905.21 HSA 2002
Total Dissolved
I mile Creek Solids
36 Highland HSA Phosphorus 1.2 miles 2002 (905.32) Cloverdale
Total Dissolved Creek
Solids
37 Sutherland HSA Sutherland Entire Reservoir Color Entire 2002 (905.53) Reservoir Reservoir 38 Miramar Reservoir Los
Sedimentation I HA (906.10) Penasquitos Entire Lagoon
Siltation 1998 469 acres Lagoon
39 Miramar Reservoir Pacific Ocean Torrey Pines State Beach at Del Bacterial 0.4 miles 2002 HA (906.10) Shoreline Mar (Anderson Canyon) Indicators E 40 Scripps HA La Jolla Shores Beach at El Paseo
(906.30) Pacific Ocean Grande Bacterial 3.9 miles 1998
Shoreline La Jolla Shores Beach at Caminito IndicatorsE
Del Oro
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. La Jolla Shores Beach at
Vallecitos
La Jolla Shores Beach at Ave de la,
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. Playa
last updated 9/23/2003
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Storm Water Management Plan
Chapter 5— FLOW-BASED BMPs
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5.1 - Design Criteria
U 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
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and removal of pollutants from the runoff.
Per the request of the City of Carlsbad, 85th percentile flow calculations were
performed using the Rational Method. The basic Rational Method runoff procedure
is as follows:
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Design flow (Q)=C*l*A
Runoff Coefficient C - In accordance with the County of San Diego standards, the
weighted runoff coefficient for all the areas draining to the treatment unit was
I 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
I 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
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.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, I contaminated sediments, metals, hydrocarbons and floating contaminants from
-• surface runoff. Combining swirl-concentrator and flow-control technologies to
eliminate turbulence within the systemtheVoJjechs System ensures the effective I capture of sediment and oils and prevents resuspension of trapped pollutants for
flows up to 25 cfs.
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Pollutant of Concern BMP Categories
Hydrodynamic VortechsTM
Separation Stormwater
Devices 2 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
The City will periodically assess the performance characteristics of these BMPs to update
this table.
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 efficiehc, appFicnt must provide evidence supporting use
Sources: Guidance Specifying Management Measures for Sources of Nonpoint Pollution in
Coastal Waters (1993), National Stormwater Best Management Practices Database (2001),
and Guide for BMP Selection in Urban Developed Areas (2001).
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Other features of the Vortechs Systems include the following:
Large capacity system provides an 80 percent net annual Total Suspended
Solids (TSS) removal rate
I Unit is installed below grade
Low pump-out volume and one-point access reduce maintenance costs
I Design prevents oils and other floatables from escaping the system during
cleanout
Enhanced removal efficiencies of nutrients and heavy metals with offline
I configuration
The tangential inlet to the system creates a swirling motion that directs settleable
solids into a pile towards the center of the 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 85th
percentile flow.
5.3 - Pollutant Removal Efficiency Table
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La Costa Greens - Recreation Center
Storm Water Management Plan
5.4 -Maintenance Requirements
Flow-based storm 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 I to 4 times per year.
Maintenance of the Vortechs units involves the use of a "vactor truck", 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. 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 size of the unit.
5.5 Schedule of Maintenance Activities
Vortechs Units:
Target Maintenance Date - March 15th
Maintenance Activity - Annual inspection and cleanout. Clear grit chamber of each
unit with vactor truck. Perform visual inspection. Remove floatables.
5.6 - Annual Operations and Maintenance Costs
Vortechs Units:
The following outlines approximate Annual Maintenance costs for the proposed
Vortechs units. Costs assume a 3 man crew:
Maintenance for Model PC 16x24
Periodic Inspection, Maintenance and Monitoring = $800
Annual Cleanout Cost = $3,000
Subtotal = $3,800 - -•
Contingency = $380
Total = $4,180
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Storm Water Management Plan
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,
I antifreeze, paint, household cleaners and solvents. Homeowners should be
educated as to the proper use, storage, and disposal of these potential storm water
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runoff contaminants.
Per the RWQCB Order, the following housekeeping activities are deemed unlawful
and are thus prohibited:
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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
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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)
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- Discharges of food-related wastes (grease, food processing, trash bin wash
I water, etc.).
6.3 - Automobile Use
I Urban pollutants resulting from automobile use include oil, grease, antifreeze,
hydraulic fluids, copper from brakes, and various fuels. Homeowners should be
I educated as to the proper use, storage, and disposal of these potential storm water
contaminants.
I 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 I repair garages, or other types of automotive service facilities.
- Discharges resulting from the cleaning, repair, or maintenance of any type of
I 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 I -
washing, steam cleaning, power washing, and carpet cleaning.
I 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.
I 6.4 -Site Design BMPs
l The proposed project site consists of a single 3 acre lot. Approximately 75% of the
project site, 2.25 acres, will not be developed and will be preserved as open space.
This will minimize the pollutant loads generated and potentially discharged from the
I site. Furthermore, while the project does not depend on this open space to provide
treatment of potential pollutants, there will be a natural benefit derived from its
existence, both as a natural buffer between the site and water bodies and as a
I cleansing mechanism.
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La Costa Greens - Recreation Center
Storm Water Management Plan
Chapter 7— SITE BMP DESIGN
VORTECHS TREATMENT UNITS
7.1 - BMP Locations
The improvement design for the project site incorporates the construction a single
stormwater treatment device. Runoff from the Recreation Center and the northern
portion of Neighborhood 1.12 will be treated by a Vortechs Model PC16x24 storm
water quality unit. The storm water quality treatment unit, treating runoff from the
project site, has been sized to treat 85th percentile design flow from Neighborhood
1.09, 1.10, a portion of Neighborhood 1.12 and offsite areas to the east, all which
drain through Neighborhood 1.10.
7.2 - Determination of Design Treatment Flows
The 85th percentile flow rate for the northern portion of Neighborhood 1.12 (inclusive
of the Recreation Center) has been calculated using the Rational Method. Required
data for the Rational Method Treatment flow determination is as follows:
- Drainage Area (A) = 196.05 acres (Neighborhoods 1.09, 1.10, northern
portion of 1.12, and offsite areas)
Rainfall Intensity (I) = 0.20 inches per hour
Runoff Coefficient (C) = 0.53
The site's overall runoff coefficient was derived based upon a weighted average of
each area tributary to the treatment unit and the associated runoff coefficient. Using
this method, the site's runoff coefficient was estimated to be 0.53. Bases on this
data the treatment flow for the storm water treatment unit was determined to be
20.78 cfs.
7.3 - Vortechs Treatment Unit Selection
Per the "Vortechnics Engineered Stormwater Products" manual, dated November,
2001 (excerpts attached), the Vortechs Model PC16x24 has a design flow rate of
40.0 cfs. This unit (details attached), as proposed on the improvement plans, is
configured as 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 of
the 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
I upstream of the weir. These losses wiD. 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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Storm Water Management Plan
The Vortechs Model PC16x24, with a peak treatment flow design capacity of 40.0
cfs, was selected because of the results of the Flow Calculation spreadsheet,
provided by Vortechnics and included in the Attachments section of this report, show
that during the 100-yr storm the diversion weir would divert 39.5 cfs through the
treatment unit. Therefore the unit has been sized to handle the flow of 39.5 cfs.
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j I
VILLAGES OF LA COSTA
NEIGHBORHOOD 1.09, 1.10 AND PORTION OF 1.12 (NORTH)
TREATMENT FLOW DETERMINATION:
Q=C*IA
TREATMENT AREA 196.05 ACRES
RAINFALL INTENSITY 020 IN/HR /
WEIGHTED CURVE NUMBER 0.53 i
Q = 20.78 CFS
10:45 AM8/1 8/2003 Sheetl RM-TREATMENT FLOW.xls
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Vortechnics
FLOW CALCULATIONS
La Costa Greens Village Neighborhood
Carlsbad, CA
PC16X24
System 1.10
Vortechs Orifice
Cd = 0.56
A (ft2) = 9.00
Crest Elevation (ft) = 99.50
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
(It) (It) (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
050 100.00 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(Y1QO p475 SOC 2!475
- 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
j.102 uO 4 52 C 00 31 5 82
First highlighted row indicates treatment of the 85th percentile flow (first flush) before bypass flow occurs. Second ro
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 liChecked b):
Vortechs System
104.5
104.0
103.5
103.0
iP 102.5
102.0
16 101.5
101.0
100.5
100.0
99.5
99.0
Stage Discharge Curve
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\4404A0SPC16X24.xls AP 10/10/2003
VortechsTM Storm water Treatment Systems
VQRTECHS SYSTEM ESTIMATED NET ANNUAL TSS REMOVAL EFFICIENCY
Vortechnics La Costa Greens Village Neighborhood
Carlsbad, CA
PC 16X24
System 1.10
1 (193.5 acres) x (0.53) x (449 gpm/cfs) Design Ratio = 2289 (201.1so =
Bypass occurs at an elevation of 101 (at approximately 55 gpm/sf)
Rainfall Intensity Operating Rate ¼ Total Rainfall Rmvl. Effcy4 Rel. Effcy
gpmlsf Volume (¼) (%)
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%
¼ rain falling at >0.7"/hr or bypassing treatment = 2.9%
Assumed removal efficiency for bypassed flows = 0.0%
Removal Efficiency Adjustmene = 7.6%
Net Annual TSS Removal Efficiency = 82%
1 - Design Ratio = (Total Drainage Area) x (Runoff Coefficient) 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.
2- Operating Rate (gpm/sf) = intensity (/hr) x Design Ratio.
3 - Based 10 Years of Hourly Precipitation Data From NCDC Station 7740, San Diego 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.
Calculated by: WSG 10/1012003
--=lChecked by:
f:\data\vortechn\projects\4404ADSPC1 6X24.xls AP 10/10/2003
1,—a.
SWIRL CHAMBER
VAULT WALL
CONTACT POINT
SEE NOTE 3
16'—O
<ALUMINUM SWIRL CHAMBER
SEE NOTE 2
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3' SQ. OPENINGS IN 7r TOP SLAB FOR HATCHES
(TYP. OF 3)
A
11O !G1
-Hr----- —
24' DIA. OPENING IN TOP SLAB FOR
MANHOLE FRAME & COVER (TYP OF 3)
=
F- I
STEEL REINFORCED
POLYPROPYLENE
MANHOLE STEPS if 00
4 ,.
. -
8 FLOATABLES BAFFLE A
SECTION t7
(SWIRL CHAMBER NOT SHOWN)
34 0 HOLE FOR
24 0 RCP OUTLET PIPE
t 5'—O ABOVE FLOOR
OULET PIPE INV. ELEV. 78.79'
RIM ELEV. 95_81 — 96.72' MATCH FINISHED GRADE
TOP OF SLAB ELEV. 86.29' 4\
2'—lO'
tHy. 78.79'd
EL. 73.48.
6 FLOW
—CONTROL
BAFFLE B
-
'-3-
U
MANHOLE 340 HOLE FOR STEPS
24'0 RCP INLET PIPE
5'—O ABOVE FLOOR
INLET PIPE INV. ELEV 78.79' 1/ _ BUTYL RUBBER SEALANT BETWEEN BASE SECTION AND ALUMINUM CHAMBER,
TYPICAL—LONG WALLS ONLY
180' ALUMINUM ANGLE SEALING FLANGE PLAN VIEW
INSTALLED WITh NEOPRENE GASKET AT
BASE AND CONCRETE FLOOR
RISER, GRADE RINGS OR
BLOCK AS REQUIRED
TO MATCH RIM ELEVATION
TO FINISHED GRADE
(TYP. ALL HATCHES/MANHOLES)
5'iQ
INLET/OUTLET
1,—a. 24'-0' 1'—O"
CONUCTIONNOSAND SPECIFiCATIONS
CONCRETE VAULT SHALL BE CONSTRUCTED IN CONFORMANCE WITH
SPECIFICATIONS SECTIONS; 3100 — CONCRETE FORMWORK. 03200 — CONCRETE REINFORCEMENT. 03300 — CAST—IN—PLACE CONCRETE AND 3370 — CONCRETE CURING.
VORTECHS SYSTEM COMPONENTS SHALL BE SUPPLIED BY VORTECHNICS AND
INSTALLED BY THE CONTRACTOR IN CONFORMANCE WiTh SPECIFICATIONS
SECTION 03105 — VORTECHS STORMWATER TREATMENT SYSTEM ASSEMBLY.
THE ALUMINUM SWIRL CHAMBER SHALL BE AFFIXED TO THE SIDE AND END
WALLS OF THE VAULT USING DROP—IN OR WEDGE ANCHORS INSTALLED AT THE
LOCATIONS OF THE PREDRILLED HOLES IN THE SWIRL CHAMBER (12 TOTAL).
THE ALUMINUM WEIR AND ORIFICE PLATES SHALL BE MOUNTED ON THE
FLOW CONTROL WALL USING DROP—IN OR WEDGE ANCHORS INSTALLED AT THE
LOCATIONS OF THE PREDRIILED HOLES IN THE PLATES (8 TOTAL). A BEAD
OF POLYURETHANE CAULK SHALL BE APPLIED TO THE BACK SIDE OF EACH PLATE IMMEDIATELY PRIOR TO BOLTING IT TO THE FLOW CONTROL WALL.
CONCRETE USED IN THE MANUFACTURE OF THE CAST—IN—PLACE PORTIONS
OF THE VORTECHS STORMWATER TREATMENT SYSTEMS SHALL CONFORM TO
PAR1E 2 OF SPECIFICATION SECTION 03300 — CAST—IN—PLACE CONCRETE.
G. WATERSTOPS SHALL BE UTILIZED AT ALL CONSTRUCTION JOINTS.
IF PRECAST ROOF SLABS ARE UTILIZED THEN ALL ROOF SLAB JOINTS SHALL BE COVERED WITH A BUTYL RUBBER JOINT WRAP PLACED IN
CONFORMANCE WITH THE MANUFACTURER'S SPECIFICATIONS.
CONCRETE WALLS SHALL NOT BE BACKF1LLED UNTIL CONCRETE STRENGTH
HAS REACHED 3000 PSI.
(3) .3' SQ. HATCHES SHALL BE SYRACUSE CASTING COMPANY HATCH MODEL
#01-7110, OR APPROVED EQUAL
(3) 24 DIA. i 4 H. MANHOLE FRAMES AND PERFORATED COVERS SHALL BE
CAMPBELL CASTING #1009A, OR APPROVED EQUAL CAST WITH THE VORTECHNICS LOGO.
HATCHES AND MANHOLE FRAMES AND COVERS SHALL BE PROVIDED BY
VORTECHNICS
This CADS file Is for the PUTPOOC of specifying stcimwotsr treatment equipment to be furnished by Vcrt,chnic,, Inc. and may only be lronof,n,d to other documents exactly an provided by Vartechaloc. Tlflo block information, excluding the Vcrt.chnlcs logo and the Verlechi Siorrowater Treatment Syot.m designation and potent number, may be deleted it necessary. Revisions to any part of this C0D file without prior coordination with Voriochnics shall be considered unauthorized U34 of proprietary Information.
DATE: 12115/03 (REVS) OWG No. 1Of 6
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Plan View Grit Che
The awning motion created by the tangential inlet directs settleable • 11 L_ solids toward the center of this 1 . . chamber. Sediment Is caught in.... .1 (l the swirling flow path and settles • back onto the after the pile storm event is over. . - • .•
• r.crr 09 Chambex/. Fl,,ccntri Oil Chbe& Bc1e WaIl • Baffla Waft.. C&flb The canter baffle tra floatables in 1
:- .. \ • . :1.: .: • •,• .the oil chamber,even during clean:-
Highly resistant to flow.stirg '°
ut
'.:.•' Flow CoxtrlC1icubd
I weir dnd orificis Ac W* controls •
• .,. - .1) Raise ieveand volume in ,the. system as flow rate Increases, arcd " .. ••
•.. 21 gradually drain the tem:ai.c Eavatiot \liew: Dry-Weather.
... ...flow rate subsides.
.. : :i_ .....:. •... ........::.:::
1) Iiit1cl Wet Wecrffier Phase During a two-month storm event the water 1vel 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 ccrd'clied outflow rate, the tank flits and the floating contaminant layer accu mulated from past storms rises. Swirling action increases at this stage, while sediment pile remains stabl
e
.
3) Full Cpcdt7 Phase
When the high-flow cutlet approaches hill discharges srm drains era flowing at peak cepaci The Vcrtechs Sjstam is
desioned to match 'icur de.sicn stnrrm firiw r1r '-
4) Storm SuEsiderice Phase/C1eaig
Treated runoff is decanted at a controlled rate, restoring the water level to a low dry-weather volume and revealing a cOfltCZl
1J1Lt \d Stormwater Treatment Stem
1 4 -_---D Plus 6T'jpicI Ij
( 1/4 h 1•.
tr
—.—
Plan View E1evacn View
Egg
ATE,
Its
long
Isms
Al lcaa tn4a artach Saan,a wlthta bijiaaa.. &zIr catàrla
aead an p cltnana aquaz' tcc.t c charharauafaca area fcc each ¶Q gpm orpaelç daain arm llcw rata (e.g.. 1Oaer storm). Foa mare o dacale abatma achrmca siabac crttana rder.to Vbrtinmcd Teclwmcat uilln 3. af Sediment "g? nit, &a foot sump.
4.; . Conecan dataU aavarjdépandg on-thij spacRo appkadion. Any aIraØra to the ;fah dmrt apecill cariane will appaeran Y dtiaicanl and shop drawings. Peer call Vcrcrmlca for the wem at spa-. a&2 Varcacirn s'stema 11needa4.
- Special Nqp. i1fl starge cpac.wiient !needd eaa apac c+squlrnien far spiN ncalI,ffien, can sized to meet the storage ra menld? the selected nacdet. Varaachnics taqinicaI staff will OprTt 55t5fl . gacT7aQy taj,eae containment req*ement3 'itliin a camcdy elaed Vrirchs System.
. • .• . • . • •t •.. ••.•.. . .• •
tech - .ii..••.•-..:_. . . .• . .
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.
f or mail the worksheet to
Vortechnics with your site plan,
and we'll produce detailed
Vortechs System scale draw-
ings free of charge.
Vortechs System Inlet/Outlet Coithgurations . Vortechs Systems can be configured to accorm-
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.
=)H=
End Inlet r Side Inlet
TO
polish
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La Costa Greens - Recreation Center
Storm Water Management Plan
Chapter 8 — FISCAL RESOURCES
8.1 Fiscal Mechanism Selection
The table below illustrates the maintenance mechanism selection criteria
and its associated fiscal funding source. The shaded portion of the table
highlights the mechanism associated with the La Costa Greens
Recreation Center.
>>>>>>>>>>>>>> Increased risk, complexity, cost or other maintenance factors>>>>>>>>>>>>>>>>>
(Private Responsibility) (Public Responsibility)
First Category Second Category Third Category Fourth Category
Importance of Minimal
concern;
Need to make sure
private owners
Warrants Flood
Control Dist. (FCD)
Broader public
responsibility for Maintenance
inherent in maintain and assuming maintenance and
BMP or provide City ability to responsibility, with funding (beyond
property step in & perforni funding related to project)
stewardship maintenance project
Typical BMPs Biofilter (Grass
swale, grass
[First cat. plus.]
Minor wetland swale,
[Second cat. plus:]
Wetland swale or
[Third cat. plus:]
Retrofit public
strip, vegetated Small detention bioretention; storm drain
buffer); basin, Single storm Detention basin inserts, etc.
drain insert I Oil- (extended/dry); Wet Master plan
Infiltration water separator . ponds & wetlands; facility
basin/trench Catch basin insert & Multiple storm drain that serves area
screen inserts; Filtration larger than project
Systems
Mechanisms 1. Stormwater Ordinance requirement 1. Dedication to FCD. 1. Dedication to
[section 67 319(a)&(h)] with code 2. Formation of FCD or
enforcement benefit area County.
2. Nuisance abatement with costs 3. FCD maintenance FCD / County
charged back to property owner documentation maintenance
Condition in ongoing permit such as documentation
a Major Use Permit (if project has
M UP)
Notice to new purchasers
[67.819(e)]
E. Subdivision public report"white
papers' to include notice of
maintenance responsibility
6. Recorded
easement
agreement
wlcovenant
binding on
successors
Funding None Security (Cash Start-up interim: Varies: gas tax for
Source(s) necessary Ideposit, Letter of
Credit, or other
Developer fee
covering 24 months
BMP in road
ROW, Transnet
acceptable to City) of costs for CIP projects,
for interim-period, Permanent: Special funding or
Agreement for FCD Assessment General funding
security to contain per FCD Act Sec for others.
provisions for 105-17.5
release or refund, if
not used.
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La Costa Greens - Recreation Center
Storm Water Management Plan
8.2 Agreements (Mechanisms to Assure Maintenance) I There is a single Vortechs Model PC16x24 treatment unit that treats
Neighborhoods 1.09, 1.10 and the northern portion of Neighborhood 1.12 of
I the proposed La Costa Greens development. Storm water quality units fall
within maintenance category two based on the City's Guidelines for the Storm
Maintenance Plan.
I
Water
Funding for all water quality treatment devices is provided by the Master
Home Owners Association of the La Costa Greens development. The Home
I Owners Association will be responsible to perform the maintenance activities
and to ensure adequate funding. The maintenance agreement(s) will be
found with the Home Owners Association's secretary. Security to fund
I
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"backup" maintenance which would be performed by the City in the event that
the HOA's maintenance is inadequate is required.
I The City of Carlsbad Watershed Protection, Storm Water Management, and
Discharge Control Ordinance require ongoing maintenance of BMPs to
I
ensure the proper function and operation of theses BMPs. Costs for this
maintenance will be the responsibility of the Home Owners Association at the
time of inception and by the contractor during construction of the
development. The Vortechs treatment unit will require maintenance activities I as outlined in Section 5 of this report. The approximate total annual cost for
maintenance will be $4,180 for the Vortechs. Maintenance costs shall be
I prorated by the La Costa Greens Master HOA amongst the Neighborhoods.
Additionally, a BMP Maintenance Agreement with Easement and Covenant
will be entered into with the City which will function in three ways. This I agreement will commit the land to being used only for purposes of the BMP;
The agreement will include an agreement by the landowner to maintain the
facilities in accordance with the SMP (which would be passed on to future I purchasers or successors of the landowner as a covenant); This agreement
will include an easement giving the City the right to enter onto the land and
I any adjacent land needed for access to maintain the BMPs.
The Developer must provide the City with Security to back up the
maintenance agreement which would remain in place for an interim period of I five years. The amount of the security shall equal the estimated cost of two
years of maintenance activities. The security can be a Cash Deposit, Letter of
I Credit or other form acceptable to the City.
For further information, refer to the "Storm Water Management Plan for La
Costa Greens Neighborhood I .12",. Hwnsaker & Associates San Diego, Inc.; I August 17th 2003.
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La Costa Greens - Recreation Center
Storm Water Management Plan
Chapter 9 — 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
Carlsbad", City of Carlsbad, California; April 1993.
"Master Drainage and Storm Water Quality Management Plan", City of Carlsbad,
California; March 1994.
"Hydrology Study for La Costa Greens -Phase I Neighborhood 1.10", Hunsaker &
Associates San Diego, Inc.; December 23, 2001.
"Hydrology Study for La Costa Greens - Phase I Neighborhood 1.12", Hunsaker &
Associates San Diego, Inc.; December 23, 2001.
"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.
I "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
I of San Diego County, and San Diego Unified Port District", California Regional
Water Quality Control Board - San Diego Region; February 21, 2001.
I "Water Quality Plan for the San Diego Basin", California Regional Water Quality
Control Board - San Diego Region, September 8, 1994.
I "Vortechnics Storm Water Treatment System Manual", Vortechnics; Revised May
2000.
I "Preliminary Storm Water Management Plan for La Costa Greens Neighborhood
1.12", Hunsaker & Associates San Diego, Inc.; August 17, 2003.
"Preliminary Storm Water Management Plan for La Costa Greens Neighborhood
1.10", Hunsaker & Associates San Diego, Inc.; August 18, 2003.
"Master Hydrology Study and Revised Hydrablk Study for La Costa Greens - Phase
I Neighborhoods 1.08 - 1.14", Hunsaker & Associates San Diego, Inc.; August 4,
u
2003.
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