HomeMy WebLinkAboutCT 07-08; LA COSTA SPA & RESORT VILLAS; STORM WATER MANAGEMENT PLAN; 2007-10-19RECEIVED
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CITY OF CARLSBAD
PLANNING DEPT
Storm Water Management Plan
LA COSTA RESORT - TENTATIVE MAP
PLANNING AREA 3— BUILDING 10
CITY OF CARLSBAD
SAN DIEGO COUNTY, CALIFORNIA
(MAP NO. 15108, CT 07-09
SUP 03-03, 03-06)
October 19, 2007
Prepared for:
W2007 La Costa I, LLC
2100 Costa Del Mar Road
Carlsbad, CA 92009
CONTACT: Chevis Hosea, President
Prepared by:
RBF CONSULTING
5050 Avenida Encinas, Suite 260
_______ Carlsbad, CA 92008
760.476.9 3
CONSULTING
M.
Contact Person: C60283 Tim Thiele, P.E.
CNIL
RBF JN 55-100221
STORM WATER MANAGEMENT PLAN
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I TABLE OF CONTENTS
TABLE OF CONTENTS .................................................................................................. I
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PURPOSE OF SCOPE...............................................................................2
PROJECT INFORMATION.........................................................................2
2.1 Project Description......................................................................................2
2.2 Project Activities .........................................................................................2
I 3 WATER QUALITY CONDITIONS OF CONCERN ......................................4
3.1.1 Potential Pollutants.....................................................................................4
3.1.2 Pollutants of Concern..................................................................................6
3.1.3 Conditions of Concern ................................................................................7 I 4 POST-CONSTRUCTION BEST MANAGEMENT PRACTICE PLAN..........8
4.1 Site Design BMPs.......................................................................................8
I 4.2
4.3
Source Control BMPs .................................................................................9
BMPs for Individual Project Categories.....................................................11
4.4 Treatment Control BMPs...........................................................................12
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4.5
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Construction-Phase BMPs........................................................................15
LOW IMPACT DEVELOPMENT...............................................................16
5.1 Porous Pavement .....................................................................................16
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5.2
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Roof Runoff Disconnect............................................................................16
MAINTENANCE .......................................................................................16
POST-CONSTRUCTION BMP SITE MAP....................................................................17
I TABLE OF FIGURES
Figure2-1 Vicinity Map .................................................................................................3
I Figure 4-1 Kristar Floguard Plus® Inlet Insert ............................................................15
I Table
LIST OF TABLES
3-1 Anticipated and potential pollutants by project type (San Diego County,
2002a) ........................................................................................................4
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Table 3-2
Table 4-1
Summary of 303(d) impairments of downsteam water bodies.....................7
Site design BMPs alternatives.....................................................................8
Table 4-2 Source-control BMP alternatives .................... .... .... . ....... .. ........................... 9
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Table 4-3
Table 4-4
Carlsbad SUSMP Individual Project Categories........................................12
Treatment Control BMP Selection Matrix (San Diego County, 2002a).......13
Table 4-5 Treatment-Control BMP alternatives.........................................................13
I APPENDIX
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A STORM WATER REQUIREMENTS APPICABILITY CHECKLIST
B BMP CALCULATIONS
I C DRAINAGE NARRATIVE
DAPPROVED STORM WATER MANAGEMENT PLAN
La Costa Resort - Tentative Map
Planning Area 3, Building 10 1
Storm Water Management Plan -
STORM WATER MANAGEMENT PLAN
I PURPOSE AND SCOPE
This report is a site-specific storm water management plan that supplements the
approved Master Storm Water Management Plan prepared by Rick Engineering, dated
October 29, 2003. Presented within this document are the water quality measures
required for the development of Planning Area #3 - Building 10 at the La Costa Resort
and Spa, in order to fulfill the requirements of the City of Carlsbad. This report also
describes the implementation and maintenance of water quality Best-Management
Practices that will be installed on the site.
2 PROJECT INFORMATION
2.1 Project Description
The project is located within the City of Carlsbad at the La Costa Resort and Spa (CT-
07-08). The campus is bound by El Camino Real to the west, Arenal Road to the north,
and San Marcos Creek to the south. Planning Area 3 is located at the northeast corner
of the intersection of El Camino Real and Costa Del Mar Road (see Figure 2-1).
The existing site is a vacant dirt lot. The western boundary is sloped at 2:1 from the
existing screen wall; the remainder of the site is graded at approximately 5% toward the
southern property line. There are no existing buildings within the project site. The site is
located approximately 1,000 feet from the San Marcos Creek. The project site contains
side slopes of 2:1 or less. The project is not located within the Coastal Zone. Iti land use
designation is Travel/Recreation Commercial. There are no sanitary landfills, historical,
archaeological or paleontological resources located within a half-mile of the project site.
2.2 Project Activities
I The project will consist of a commercial dwelling building (9,315 sq. ft.) and parking lot
(12,000 sq. ft. Landscaping will be incorporated into the planter islands and at the
perimeter of the building and parking lot. There is one private driveway proposed as part
I of this project. The driveway will provide access to the site from Building 4 and connect
with the site located to the south. Drainage from the project will be directed into a
proposed storm drain system and connected to an existing piping system that will
I ultimately outlet to the San Marcos Creek located at the southerly boundary of the La
Costa Resort campus. Approximately 90% of the site will be re-graded as part of this
project.
I The project is considered a high priority project by the City of Carlsbad (See Appendix
A - "Storm Water Requirements Applicability Checklist"). Therefore, the project will
I incorporate all applicable permanent storm water management requirements. These
include the site design and source control BMPs, BMPs applicable to individual priority
project categories, and treatment control BMP requirements.
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La Costa Resort - Tentative Map
Planning Area 3, Building 10 2
Storm Water Management Plan fWF
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STORM WATER MANAGEMENT PLAN
Figure 2-1
Vicinity Map (Reference Thomas Bros. 11271147)
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SITE
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:- 02 O5Thr Bw M
La Costa Resort - Tentative Map
Planning Area 3, Building 10 3
Storm Water Management Plan Fw.
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STORM WATER MANAGEMENT PLAN
3 WATER QUALITY CONDITIONS OF CONCERN
3.1 Potential Pollutants
The proposed project is not expected to generate significant amounts of pollutants, but
many constituents are generally anticipated for projects in this category (Table 3-1).
Table 3.1 Anticipated and potential pollutants by project type (San Diego County, 2002a).
V" Anticipated Pollutants General Pollutant Categories
P Potential Pollutants
a) U C
-D D
Priority Project Categories ,
U) ci) a) (D
i 2 >
- a
(.1)
E Q) 0
-
C a
E
o C a)
a) U)
.
- J z
0 5) i 0
0 0) X
0
=
0 ° M CL
Detached Residential
Attached Residential if' I if' p)1) p))) p 1
Commercial (>100,000 sf) p) pci
-
p(2) I p)5) I p)) pC5
Auto Repair Shops
Restaurants
Hillside Development (>5,000 sf)
Parking Lots p(i) p(i) j ( pCi) j p)i)
Streets, Highways, and Freeways I P I p(4) I p)S) f'
Retail Gasoline Outlets if' p(4) I I
A potential pollutant if landscaping exists on-site;
A potential pollutant if the project includes uncovered parking areas;
A potential pollutant if land use involved food or animal waste products;
Including petroleum hydrocarbons;
Including solvents.
As indicated in Section 2.2, the project will consist of a commercial dwelling building
totaling 9,315 sq. ft. and 12,000 sq. ft. of parking lot (See Site Map), thus the project falls
into the parking lot priority project category, as indicated in Table 3-1. Potential
pollutants of concern associated with this priority project category include:
La Costa Resort - Tentative Map
Planning Area 3, Building 10
Storm Water Management Plan
+ Sediments (since there will be landscaped areas on site);
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STORM WATER MANAGEMENT PLAN
:. Nutrients (since there will be landscaped areas on site);
:• Metals (associated with vehicle parking);
:• Litter and trash collecting in the drainage systems;
:• Oxygen-demanding substances including biodegradable organic material and
chemicals;
Oils, grease, and other hydrocarbons emanating from paved areas on the site;
Pesticides used to control nuisance growth; and
3.1.1 Sediment
Sediments are 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, lower young aquatic organisms survival rates, smother
bottom dwelling organisms, and suppress aquatic vegetation growth.
3.1.2 Nutrients
Nutrients are inorganic substances, such as nitrogen and phosphorus. They 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.
3.1.3 Metals
Metals are raw material components in non-metal products such as fuels, adhesives,
paints, and other coatings. The primary sources of metal pollution in storm water are
typically commercially available metals and metal products. Metals of concern include
cadmium, chromium, copper, lead, mercury, and zinc. Lead and chromium have been
used as corrosion inhibitors in primer coatings and cooling tower systems. At low
concentrations naturally occurring in soil, metals are not toxic. However, at higher
concentrations, certain metals can be toxic to aquatic life. Humans can be impacted from
contaminated groundwater resources, and bioaccumulation of metals in fish and
shellfish. Environmental concerns, regarding the potential for release of metals to the
environment, have already led to restricted metal usage in certain applications.
3.1.4 Trash and Debris
Trash (such as paper, plastic, polystyrene packing foam, and aluminum materials) and
biodegradable organic matter (such as leaves, grass cuttings, and food waste) are
general waste products on the landscape. The presence of trash and debris 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. Also, in areas where stagnant water exists, 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.
3.1.5 Oxygen-Demanding Substances
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La Costa Resort -Tentative Map
Planning Area 3, Building 10 5
Storm Water Management Plan
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This category includes biodegradable organic material as well as chemicals that react
with dissolved oxygen in water to form other compounds. Proteins, carbohydrates, and
fats are examples of biodegradable organic 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.
3.1.6 Oil and Grease
Oil and grease are characterized as high-molecular weight organic compounds. The
primary sources of oil and grease are petroleum hydrocarbon products, motor products
from leaking vehicles, esters, oils, fats, waxes, and high molecular-weight fatty acids.
Introduction of these pollutants to the water bodies are very possible due to the wide
uses and applications of some of these products in municipal, residential, commercial,
industrial, and construction areas. Elevated oil and grease content can decrease the
aesthetic value of the water body, as well as the water quality.
3.1.7 Pesticides
I Pesticides (including herbicides) are chemical compounds commonly used to control
nuisance growth of organisms. Excessive application of a pesticide may result in runoff
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containing toxic levels of its active component.
3.2 Pollutants of Concern
I The Environmental Protection Agency (EPA) is the primary federal agency responsible
for management of water quality in the United States. The Clean Water Act (CWA) is
the federal law that governs water quality control activities initiated by the EPA and
I others. Section 303 of the CWA requires the adoption of water quality standards for all
surface water in the United States. Under Section 303(d), individual states are required
to develop lists of water bodies that do not meet water quality objectives after required
I levels of treatment by point source dischargers. Total maximum daily loads (TMDLs) for
all pollutants for which these water bodies are listed must be developed in order to bring
them into compliance with water quality objectives.
I The project is located within the San Marcos hydrologic area of the Carlsbad hydrologic
unit. Receiving waters for the project site include the San Marcos Creek, the Batiquitos
Lagoon and ultimately the Pacific Ocean.
I Table 3-2 summarizes the receiving waters and their classification by the RWQCB Region 9.
I Hydrologic Approximate 303(d) Receiving Water Unit Distance
Code From Site Impairment(s)
Pacific Ocean Shoreline— San Marcos HA 904.50 2.5 mi Bacteria Indicators
Batiquitos Lagoon - San Marcos HA 904.51 0.5 mi None
San Marcos Creek - San Marcos HA 904.51 1,000 ft DDE, Phosphorus,
Sediment Toxicity
La Costa Resort - Tentative Map
Planning Area 3, Building 10 6
Storm Water Management Plan fWF
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3.3 Conditions of Concern
I According to the City of Carlsbad SUSMP, a change to a priority project site's hydrologic
regime would be considered a condition of concern if the change would impact
downstream channels and habitat integrity. However, the changes in hydrologic
I characteristics resulting from the development of this site have already been
incorporated into the downstream storm drain system design. Runoff from Planning
Area 3 will discharge into an existing 36-inch storm drain to a diversion structure located
I just downstream of a CDS unit. The diversion structure directs water to the San Marcos
Creek and Batiquitos Lagoon. A separate drainage report (Drainage Study for La Costa
Resort & Spa, prepared by Hunsaker & Associates, dated September 15, 2006) has
I been prepared to support the design of the existing storm drain system. This study
assumed ultimate conditions for the La Costa Resort & Spa campus when determining
pipe sizes and impacts to downstream facilities. Since runoff from the project
I discharges into new and existing drainage facilities that are verified to accommodate
peak runoff flow rates from a 100-year storm event, there are no conditions of concern
associated with the project. The Federal Insurance Rate Map (FIRM) for this area
shows that the project's location is out of the 100-year floodplain.
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La Costa Resort - Tentative Map
Planning Area 3, Building 10 7
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Storm Water Management Plan
I El Open Space Design
El "Green" Parking
El Alternative Payers
El Conservation Easements
El Buffer Zones
El Narrower Residential Streets
El Alternative Turnarounds
0 Urban Forestry
STORM WATER MANAGEMENT PLAN
4 POST-CONSTRUCTION BEST MANAGEMENT
PRACTICE PLAN
The project site incorporates four major types of post-construction best management
practices (BMPs). These types are (1) site design BMPs; (2) source control BMPs; (3)
site design and source control BMPs for individual priority project categories; and (4)
treatment control BMPs. In general, site design BMPs and source control BMPs reduce
the amount of storm water and potential pollutants emanating from a site and focus on
pollution prevention. Treatment-control BMPs target anticipated potential storm water
pollutants. The project will apply these BMPs to the maximum extent practicable.
4.1 Site Design BMPs
Site design BMPs aim to conserve natural areas and minimize impervious cover,
especially impervious areas 'directly connected' to receiving waters, in order to maintain
or reduce increases in peak flow velocities from the project site. The U.S. EPA (2002)
has listed several site design BMPs that can be implemented in development projects.
The project has incorporated site design BMPs to the maximum extent practicable.
Table 4-1 lists site-design BMP alternatives and indicates the practices that have been
applied to the project site.
Table 4-1 Site design BMPs alternatives.
El Eliminating Curbs And Gutters Z Landscape Design
Z Other (Explained Below)
4.1.1 Protect Slopes and Channels
Site runoff will be directed away from the tops of slopes, and all slopes will be vegetated
to provide permanent stabilization.
4.2 Source Control BMPs
Source-control BMPs are activities, practices, and procedures (primarily non-structural)
that are designed to prevent urban runoff pollution. These measures either reduce the
amount of runoff from the site or prevent contact between potential pollutants and storm
water. In addition, source-control BMPs are often the best method to address non-storm
(dry-weather) flows. Table 4-2 lists source-control BMP alternatives and indicates the
practices that will be applied at the project site.
La Costa Resort - Tentative Map
Planning Area 3, Building 10 8
Storm Water Management Plan IBF
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Table 4-2 Source-control BMP alternatives.
I Z Storm Drain Stenciling and Signage El Homeowner Outreach
Z Material and Trash Storage Area Design El Lawn and Gardening Practices
Z Efficient Irrigation Systems 0 Water Conservation
I Z Low-Irrigation Landscape Design El Hazardous Waste Management
El On-Lot Treatment Measures El Trash Management
0 Riprap or Other Flow Energy Dissipation Z Outreach for Commercial Activities
1 0 Other (Explained Below)
4.2.1 Efficient Landscape Design and Irrigation Practices
I Efficient landscape design and irrigation practices can be an effective source-control to
prevent pollution in storm water and dry-weather flows. The completed project will
I implement principles of common-area efficient irrigation, runoff-minimizing landscape
design, and an effective landscape maintenance plan to the maximum extent
practicable.
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4.2.1.1 Common-Area Efficient Irrigation
Automatic irrigation systems should include water sensors, programmable irrigation ' timers, automatic valves to shut-off water in case of rapid pressure drop (indicating
possible water leaks), or other measures to ensure the efficient application of water to
the landscape and prevent unnecessary runoff from irrigation. Drip irrigation and other
low-water irrigation methods should be considered where feasible. Common elements I of efficient irrigation programs include:
I .:. Reset irrigation controllers according to seasonal needs.
:• Do not over-water landscape plants or lawns.
:. Keep irrigation equipment in good working condition.
Promptly repair all water leaks.
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4.2.1.2 Runoff-Minimizing Landscape Design
Landscape designs that group plants with similar water requirements can reduce excess
irrigation runoff and promote surface infiltration. Landscape designs should utilize non-
invasive native plant species and plants with low water requirements when possible.
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4.2.1.3 Landscape Maintenance
The landscape maintenance plan should include a regular sweeping program of
impervious surfaces, litter pick-up, and proper equipment maintenance (preferably off-
site), and proper use of chemicals to help eliminate sources of storm water pollutants.
Common elements of an effective landscape maintenance plan include:
:•
Implementing a regular program of sweeping sidewalks, driveways, and gutters as
part of the landscape maintenance plan. Pick-up litter frequently. Provide
convenient trash receptacles for public use if necessary.
La Costa Resort - Tentative Map
Planning Area 3, Building 10 9
Storm Water Management Plan
STORM WATER MANAGEMENT PLAN
Avoid using water to clean sidewalks, driveways, and other areas.
I • Discourage washing of landscape maintenance equipment on-site. Minimize water
use and do not use soaps or chemicals. Use a commercial wash-rack facility
whenever possible.
I •:• Keep landscape maintenance equipment in good working order. Fix all leaks
promptly, and use drip pans/drip cloths when draining and replacing fluids. Collect
P
all spent fluids and dispose of them properly. Designate equipment maintenance
areas that are away from storm water inlets. Perform major maintenance and repairs
off-site if feasible.
I + Materials with the potential to pollute runoff (soil, pesticides, herbicides, fertilizers,
detergents, petroleum products, and other materials) should be handled, delivered,
applied, and disposed of with care following manufacturer's labeled directions and in
I accordance with all applicable Federal, state, and local regulations. Materials will be
stored under cover or otherwise protected when rain is forecast or during wet
weather.
:. Pesticides and fertilizers, if used, will be applied according to manufacturer's
directions and will not be applied prior to a forecast rain event. Any material
broadcast onto paved surfaces (e.g. parking areas or sidewalks) will be promptly
swept up and properly disposed.
41.2 Material and Trash Storage Area Design
There are no outdoor material storage areas associated with the proposed project. The
trash storage area will be designed to contain stored material to prevent debris from
being distributed into storm water collection areas. For example, dumpsters with lids will
be kept in a separate enclosed area to prevent debris from being scattered by wind or
animals. The trash storage area will be paved with an impervious surface such as
concrete or asphalt concrete. In addition, the trash storage area will be graded to
prevent run-on from adjoining areas.
4.2.3 Pollution Prevention Outreach for Businesses
One source-control best management practice for commercial sites is pollution
prevention outreach. For instance, at the lease signing or as part of the lease, the tenant
can be presented with a brochure to encourage them to develop and implement a
pollution prevention program. The pollution prevention program would emphasize
source reduction, reuse and recycling, and energy recovery. The following offer
suggestions for measures to be included in these areas of pollution prevention. The
pollution prevention outreach should choose the measures most applicable to the project
site for the project site.
4.2.3.1 Source Reduction
Incorporating environmental considerations into the designing of products, buildings,
and manufacturing systems enables them to be more resource efficient.
La Costa Resort - Tentative Map
Planning Area 3, Building 10 10
Storm Water Management Plan WF
STORM WATER MANAGEMENT PLAN
Rethinking daily operations and maintenance activities can help industries eliminate
wasteful management practices that increase costs and cause pollution.
Controlling the amount of water used in cleaning or manufacturing can produce less
wastewater.
I • Re-engineering and redesigning a facility or certain operation can take advantage of
newer, cleaner and more efficient process equipment.
I • Buying the correct amount of raw material will decrease the amount of excess
materials that are discarded (for example, paints that have a specified shelf life).
I 4.2.3.2 Reuse/Recycling
+ Using alternative materials for cleaning, coating, lubrication, and other production
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processes can provide equivalent results while preventing costly hazardous waste
generation, air emissions, and worker health risks.
I + Using "green" products decreases the use of harmful or toxic chemicals (and are
more energy efficient than other products).
I + One company's waste may be another company's raw materials. Finding markets for
waste can reduce solid waste, lessen consumption of virgin resources, increase
income for sellers, and provide an economical resource supply for the buyers.
I 4.2.3.3 Energy Recovery
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• Using energy, water, and other production inputs more efficiently keeps air and water
clean, reduces emissions of greenhouse gases, cuts operating costs, and improves
productivity.
4.2.3 Storm Drain Stenciling and Signage
I All new storm drain grate inlets constructed as part of this project will be signed with the
message "No Dumping - Drains to Oceans" or equivalent message as directed by the
City.
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4.3 BMPs for Individual Project Categories
The City of Carlsbad SUSMP lists ten individual project categories for which BMPs must
be provided. Table 4-3 below lists these individual project categories and indicates that
I the individual category of parking areas is applicable to the proposed project. Inlets
equipped with filter inserts treat any runoff generated and additional treatment is
provided as discussed in Section 4.4. Slopes will be vegetated to provide permanent
stabilization and to prevent erosion.
La Costa Resort -Tentative Map
Planning Area 3, Building 10 11
Storm Water Management Plan PF
STORM WATER MANAGEMENT PLAN
Table 4-3 Carlsbad SUSMP Individual Project Categories
El Private Roads
El Residential Driveways & Guest Parking
D Dock Areas
0 Maintenance Bays
C3 Vehicle Wash Areas
El Outdoor Processing Areas
El Equipment Wash Areas
Z Parking Areas
El Fueling Area
El Hillside Landscaping
4.4 Treatment Control BMPs
Post-construction "treatment control" storm water management BMPs provide treatment
for storm water emanating from the project site. Structural BMPs are an integral element
of post-construction storm water management and may include storage, filtration, and
infiltration practices. BMPs have varying degrees of effectiveness versus different
pollutants of concern. Table 4-4 below summarizes which treatment control BMPs and
removal effectiveness for certain constituents.
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La Costa Resort - Tentative Map
Planning Area 3, Building 10
Storm Water Management Plan
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Table 4-4 Treatment Control BMP Selection Matrix (San Diego County, 2002a).
Treatment Control BMP Categories
O High Removal Efficiency e Medium Removal Efficiency
O Low Removal Efficiency
? Unknown Removal Efficiency £
C
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a
a 2
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-D C o
V)
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Pollutant of Concern a) o a
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LI)
Sediment e 0 0 0 0 0 e
Nutrients e e • e
Heavy Metals 0 • 0 •
Organic Compounds ? ?
Trash & Debris 0 0 0 15
Oxygen Demanding Substances
Bacteria 0 ? 0 e
Oils and Grease 0 0 •
Pesticides ? ? 0
Including trenches and porous pavement.
Such as CDS units.
Original 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).
4.4.1 Treatment Control BMP Selection
The selection, design and siting of structural BMPs for Planning Area 1 depend largely
on the project-wide drainage plan and previously approved Master Storm Water
Management Plan, prepared by Rick Engineering, dated October 29, 2003. BMP
alternatives were evaluated for their relative effectiveness for treating potential pollutants
from the project site; technical feasibility; relative costs and benefits; and applicable
legal, institutional, and other constraints. Table 4-5 below lists treatment-control BMP
alternatives and identifies the BMPs selected for the project site.
Treatment Control BMPs function to mitigate pollutants of concern anticipated from
project activities. Receiving waters downstream of the project site are impaired for
bacterial indicators, DDE, Phosphorus and sediment toxicity, as shown in Table 3-2. The
proposed project activities are not anticipated to produce bacteria, DDE, phosphorus or
sediment toxicity, as shown in Table 3-1, there are no primary pollutants of concern
associated with the project, these are considered secondary pollutants of concern.
Treatment control BMPs for this project were chosen to treat the secondary pollutants of
concern at no less than a "low removal efficiency" as shown in Table 4-4.
La Costa Resort - Tentative Map
Planning Area 3, Building 10 13
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Table 4-5 Treatment-Control BMP alternatives.
El Vegetated Swales and/or Strips El Wet Ponds/Wetlands
El Dry Extended Detention Basins El Infiltration Basins
0 Bio-Retention Areas El Sand or Organic Filters
El Hydrodynamic Separators El Infiltration Trenches
Catch Basin/Inlet Inserts El Other (Explained Below)
Of the treatment control options available for this project, infiltration practices are not
feasible due to the preponderance of hydrologic soil type D throughout the site, which
has poor infiltration properties. Wet ponds and constructed wetlands rely on a perennial
water source, which is generally difficult to sustain in the project's and environment.
While filtration devices, such as sand filters and media filters, typically have medium to
high removal efficiencies for the project's pollutants of concern, they are aesthetically
unsuitable for use in developments such as this project. An underground sand/media
filter might improve aesthetics, but since the proposed project site consists of a generally
flat graded pad, implementing several filters for the small drainage areas is not feasible
due to the lack of required head needed to ensure that water passes through the filter.
4.4.1.1 Drainage Filter Inserts
To provide additional treatment and removal of potential pollutants, drainage inlet inserts
will be installed in all storm drain inlets capturing runoff from the parking lots. Kristar
Floguard Plus® inserts or equivalent will be specified to treat runoff for hydrocarbons and
trash/debris. The Kristar Floguard Plus® inlet insert is shown in Figure 4-1, and is
similar in design and function to other proprietary inlet inserts. Surface runoff enters the
inlet and passes over/through and adsorbent material to remove hydrocarbons, while
sediments and trash/debris are collected in the hanging basket. Recommended
maintenance consists of three inspections per year (once before the wet season and two
during, or more as may be needed) plus replacement of the adsorbent when it is more
than 50% coated with pollutants and removal of excessive sediment/debris. Each inlet
insert costs about $570 and is available locally through Downstream Services (760-746-
2544 or 760-746-2667). The inserts can be installed by Downstream Services for
additional cost or by the project construction contractor. Maintenance costs are
estimated at about $400 per year. (Refer to Appendix B for design calculations).
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I La Costa Resort - Tentative Map
Planning Area 3, Building 10 14
I Storm Water Management Plan
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Fossil Rock' Pouches
Liner
Outlet Pipe
TOP VIEW
I STORM WATER MANAGEMENT PLAN
Figure 4-1 Kristar Floguard Plus® Inlet Insert
/
Grate
Gasket
mat I
Ultimate Bypass
DebosTrup
Support Basket
4.4.1.2 Hydrodynamic Separators
An in-line storm water treatment unit (CDS unit) exists at the downstream end of the
campus-wide storm drain system, as proposed within the approved Master Storm Water
Management Plan, prepared by Rick Engineering, dated October 29, 2003. The storm
water treatment units are mechanical separators that physically reduce sediment, trash,
debris, and oil and grease from the flow and pesticides that attached to sediment. The
unit is considered a hydrodynamic separator system. The hydrodynamic separator
systems rank low to medium in removal efficiency for the project's pollutants of concern.
Refer to the approved Master Drainage Study for La Costa Resort & Spa, prepared by
Hunsaker Associates, dated September 15, 2006, for back-up calculations regarding the
storm water treatment unit.
4.5 Construction-Phase BMPs
Additional best management practices to prevent reduce, and/or treat storm water
pollution will be implemented during the construction phase of the project. Because the
site is considered a Medium Priority Construction Project by the City of Carlsbad, a
Storm Water Pollution Prevention Plan (SWPPP) will be developed for the project site
under separate cover and will be incorporated by reference into this document.
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La Costa Resort - Tentative Map
Planning Area 3, Building 10 15
Storm Water Management Plan
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STORM WATER MANAGEMENT PLAN
5 LOW IMPACT DEVELOPMENT
Low Impact Development (LID) is an alternative method of land development that seeks
to maintain the natural hydrologic character of the site. Per the Draft County of San
Diego Low Impact Development Handbook and in anticipation for the future City of
Carlsbad Municipal Permit LID requirement, LID BMPs have been included as part of
our site design. LID BMPs will collectively minimize directly connected impervious areas
and promote infiltration.
5.1 Porous Pavement
Porous pavement will be used in a portion of the parking lot. The advantages of porous
pavement are that they reduce runoff volume while providing treatment and are
unobtrusive. It is comprised of a permeable surface places over a granular course on
top of a reservoir of large stone. The porous pavement has been designed according to
the recommendations of the 2003 California New Development BMP Handbook, Fact
Sheet SD-20. Porous pavement has high removal efficiencies for all potential pollutants
identified for this site.
5.2 Roof Runoff Disconnect
A portion of the roof drainage will drain into pervious areas prior to entering the closed
drainage system. This disconnect allows an opportunity to reduce rate and increase
infiltration at the project site.
6 MAINTENANCE
To ensure long-term maintenance of project BMPs, the project proponent will enter into
a contract with the City of Carlsbad to obligate the project proponent to maintain, repair
and replace the storm water BMP as necessary into perpetuity. Security will be required
in the form of a Letter of Credit.
The site shall be kept in a neat and orderly fashion with a regularly scheduled landscape
maintenance crew in charge of keeping gutters and inlets free of litter and debris. The
landscape crew will also maintain the landscaping to prevent soil erosion and minimize
sediment transport.
The project consists of a series of catch basins, which will include Kristar Floguard Plus®
inlet inserts. It is recommended that the hydrocarbon absorption booms be replaced
four times per year. Currently the approximate cost to replace each boom is $100.00.
This amounts to a maintenance cost of $400.00 per year, per inlet.
Maintenance records shall be retained for at least 5-years. These records shall be made
available to the City of Carlsbad for inspection upon request.
La Costa Resort - Tentative Map
Planning Area 3, Building 10 16 IBF Storm Water Management Plan
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/ CATCH BASIN W/
ILTER INSERT
T
GENERAL INFORMATION
IOU AND USE MMERC!A
- - HED AND USE MMERCIAL
0 AL PLAN DESIGNATION: TRAVEL /RECRHAION COVY-
501 LAND USE COMMERCIAL
WORM DRAIN FACILITIES SiZES AND LOCATION A-
BINARY AND SUBJECT TO FINAL HYDROLOGY DE
ANCE OF HYDRAULIC CALCULATIONS BY CITY TI
BA
T-1POGRAPHY PREPARED BY VERTICAL MAPPING REPOUR
BENCH MARK
EE I CLN TERL NE MONUMENT ON EL CAM NO REAL ORE ML
OERLY FROM LA COSTA AVENUE
', FROM: NORTH COUNTY VERTICAL CONTROL DATA. PACE (BA
,A -'ON. 113122 ADJUSTED
A NGVD 1929
GAL DESCRIPTION
IN THE CITY OF CARLSBAD, COUNTY OF SAN DIEGO, STATE F
FORMA:
36 OF LA COSTA RESORT, CARLSBAD TRACT 03 01. PER MAP
' RECORDED MARCH 18. 2005
PLANNING AREA 1 BUILDING 9
',UMBLL OF 31. 2
ROSS ACREAGE 0.00 AL
'R'ENI I PRO ' - N P E 7
A- -A F-K JLJA'J ' VA TI
N1, I INLTFPVI -
OWNER/DEVELOPER
"[V HJTJ.A
E.'17 LA VOSTA I.
- JSA 'HAS
- HAD V'H309
REQUIREMENTS
RLN IF A I HE L'L: ED ABA' - A ' -
AND A .. lEFT WILL E VE HAL V F
MANENT pTAB!L LZATILLN
ALA LRE WI BE TAKEN AGENSURE E EFFICIENT
AT N 0[-'HAIFA 10 THE LANDSCAPING AND PRLVFNT ANY
EHARY RLLNOFI I SlIM IRRIGATION OL ,ECTI (N 4 2 1
B RF'L"AM A' ' A: ST'RAfE AP EA
OGEND
ATONED CONTOUR
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-
STATED ORE .
VLLRV - - -
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VC STORM DRAIN
.:AE. LOS OF FLOW
'HAl TO AREA - - -
EL CAMINO REAL
- - POST-CONSTRUCTION BMP SITE MAP
1 LA COSTA RESORT & SPA
PLANNING AREA 3- BUILDING 10
PLANNING • DESIGN • CONSTRUCTION
5050 AVENIDA ENCINAS, STE 260
CARLSBAD, CALIFORNA 92008
CONSULTING 7604769193 -FAX 7604769398 • vw?8Fcon
LE F'LAWWI1/&7AIzA 3- 1314/L1J1W,y Ic
I
'OR SAO AF'LlCABiLIV'CHECKtlST
Project Address Assessors Parcel Number(s): Project # (city use only):
216-610-08
I Complete Sections 1 and 2 of the following checklist to determine your project's permanent and
construction storm water best management practices requirements. This form must be completed
and submitted with your permit application.
I Section 1. Permanent Storm Water BMP Requirements:
If any answers to Part .A are answered "Yes," your project is subject to the "Priority Project
Permanent Storm Water BMP Requirements," and "Standard Permanent Storm Water BMP
I Requirements" in Section Ill, "Permanent Storm Water BMP Selection Procedure" in the Storm
Water Standards manual.
I If all answers to Part A are "No," and gny answers to Part B are "Yes," your project is only subject
to the "Standard Permanent Storm Water BMP Requirements". If every question in Part A and B
is answered "No," your project is exempt from permanent storm water requirements.
Part A! flnfprminp Prinrih, Prnht-f PrmnAn+ Strtrm W2+Ar QRAO
Does the project meet the definition of one or more of the priority project categories?* Yes No
Detached residential development of 10 or more units. F]
Attached residential development of 10 or more units.11 FVI
Commercial development greater than 100,000 square feet. I F-/
Automotive repair shop.
Restaurant.
Steep hillside development greater than 5,000 square feet.
Project discharging to receiving waters within Environmentally Sensitive Areas.
Parking lots greater than or equal to 5,000 ft or with at least 15 parking spaces, and
potentially exposed to urban runoff.
-
Streets, roads, highways, and freeways which would create a new paved surface that is
5,000 square feet or greater
* Refer to the definitions section in the Storm Water Standards for expanded definitions of the
priority project categories.
Limited Exclusion: Trenching and resurfacing work associated with utility projects are not
considered priority projects. Parking lots, buildings and other structures associated with utility
projects are priority projects if one or more of the criteria in Part A is met. If all answers to Part A
are "No", continue to Part B.
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Part B: Determine Standard Permanent Storm Water Reauirements.
Does the project propose: Yes No
New impervious areas, such as rooftops, roads, parking lots, driveways, paths and
sidewalks?
New pervious landscape areas and irrigation systems?
Permanent structures within 100. feet of any natural water body?
El Jj
Trash storage areas? LIJ
Liquid or solid material loading and unloading areas?
Vehicle or equipment fueling, washing, or maintenance areas? F1171 Require a General NPDES Permit for Storm Water Discharges Associated with Industrial
Activities (Except construction)?*
-
[J V 1 Commercial or industrial waste handling or storage, excluding typical office or household
waste? El V
Any grading or ground disturbance during construction?
Any new storm drains, or alteration to existing storm drains?
*To find out if your project is required to obtain an individual General NPDES Permit for Storm Water
Discharges Associated with Industrial Activities, visit the State Water Resources Control Board web site
at, www.swrcb.ca.gov/stormwtr/industrial.html
Section 2. Construction Storm Water BMP Requirements:
I If the answer to question I of Part C is answered "Yes," your project is subject to Section IV, "Construction
Storm Water BMP Performance Standards," and must prepare a Storm Water Pollution Prevention Plan
(SWPPP). If the answer to question 1 is "No," but the answer to any of the remaining questions is "Yes,"
your project is subject to Section IV, "Construction Storm Water BMP Performance Standards," and must
I prepare a Water Pollution Control Plan (WPCP). If every question in Part Cis answered "No," your project
is exempt from any construction storm water BMP requirements. If any of the answers to the questions in
Part C are "Yes," complete the construction site prioritization in Part D, below.
Part C Determine Construction Phase Storm Water Reauirernents.
Would the project meet any of these criteria during construction? Yes No
Is the project subject to California's statewide General NPDES Permit for Storm Water
Discharges Associated With Construction Activities?
Does the project propose grading or soil disturbance? LIII Would storm water or urban runoff have the potential to contact any portion of the
construction area, including washing and staging areas?
- Would the project use any construction materials that could negatively affect water quality
if discharged from the site (such as, paints, solvents, concrete, and stucco)?
F
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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 pose a 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.]
A) High Priority
Projects where the site is 50 acres or more and grading will occur during the rainy season
Projects 1 acre or more.
Projects 1 acre 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.)
Permit 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.
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
walls, single-family homes, small tenant improvements, etc.
Owner/Agent/Engineer Name (Please Print): Title:
- Aec P,ier 6t4i,ve Signature:
1/72W4 Vzlo7
Date:
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Storm Water Standards
4/03/03
APPENDIX B
DRAFT
ENVIRONMENTALLY SENSITIVE AREAS WITHIN THE CITY OF CAR LSBAD
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APPENDIX B
BMP CALCULATIONS
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Design Considerations
. Use with other BMPs
. Fit and Seal Capacity within Inlet
Targeted Constituents
R1 Sediment
E!1 Nutrients
I1 Trash
El Metals
Bacteria
El Oil and Grease
El Organics
Removal Effectiveness
See New Development and
Redevelopment Handbook-Section 5.
Drain Inserts MP-52
Description
Dram inserts are manufactured filters or fabric placed in a drop
inlet to remove sediment and debris. There are a multitude of
inserts of various shapes and configurations, typically falling into
one of three different groups: socks, boxes, and trays. The sock
consists of a fabric, usually constructed of polypropylene. The
fabric may be attached to a frame or the grate of the inlet holds
the sock. Socks are meant for vertical (drop) inlets. Boxes are
constructed of plastic or wire mesh. Typically a polypropylene
"bag" is placed in the wire mesh box. The bag takes the form of
the box. Most box products are one box; that is, the setting area
and filtration through media occur in the same box. Some
products consist of one or more trays or mesh grates. The trays
may hold different types of media. Filtration media vary by
manufacturer. Types include polypropylene, porous polymer,
treated cellulose, and activated carbon.
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California Experience
The number of installations is unknown but likely exceeds a
thousand. Some users have reported that these systems require
considerable maintenance to prevent plugging and bypass.
Advantages
Does not require additional space as inserts as the drain
inlets are already a component of the standard drainage
systems.
Easy access for inspection and maintenance.
As there is no standing water, there is little concern for
mosquito breeding.
A relatively inexpensive retrofit option.
Limitations
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Performance is likely significantly less than treatment systems
that are located at the end of the drainage system such as ponds
and vaults. Usually not suitable for large areas or areas with
trash or leaves than can plug the insert.
Design and Sizing Guidelines
Refer to manufacturer's guidelines. Drain inserts come any
many configurations but can be placed into three general groups:
socks, boxes, and trays. The sock consists of a fabric, usually
constructed of polypropylene. The fabric may be attached to a
frame or the grate of the inlet holds the sock. Socks are meant
for vertical (drop) inlets. Boxes are constructed of plastic or wire
mesh. Typically a polypropylene "bag" is placed in the wire mesh
box. The bag takes the form of the box. Most box products are
I January 2003 California Stormwater BMP Handbook 1 of 3
New Development and Redevelopment
www.cabmphandbooks.com
MP-52 Drain Inserts
one box; that is, the setting area and filtration through media occurs in the same box. One
manufacturer has a double-box. Stormwater enters the first box where setting occurs. The
stormwater flows into the second box where the filter media is located. Some products consist
of one or more trays or mesh grates. The trays can hold different types of media Filtration
media vary with the manufacturer: types include polypropylene, porous polymer, treated
cellulose, and activated carbon.
Construction/Inspection Considerations
Be certain that installation is done in a manner that makes certain that the stormwater enters
the unit and does not leak around the perimeter. Leakage between the frame of the insert and
the frame of the dram inlet can easily occur with vertical (drop) inlets.
Performance
Few products have performance data collected under field conditions.
Siting Criteria
It is recommended that inserts be used only for retrofit situations or as pretreatment where
other treatment BMPs presented in this section area used.
Additional Design Guidelines
Follow guidelines provided by individual manufacturers.
Maintenance
Likely require frequent maintenance, on the order of several times per year.
Cost
The initial cost of individual inserts ranges from less than $100 to about $2,000. The cost of
using multiple units in curb inlet drains varies with the size of the inlet.
The low cost of inserts may tend to favor the use of these systems over other, more effective
treatment BMPs. However, the low cost of each unit may be offset by the number of units
that are required, more, frequent maintenance, and the shorter structural life (and therefore
replacement).
References and Sources of Additional Information
Hrachovec, R., and G. Minton, 2001, Field testing of a sock-type catch basin insert, Planet CPR,
Seattle, Washington
Interagency Catch Basin Insert Committee, Evaluation of Commercially-Available Catch Basin
Inserts for the Treatment of Stormwater Runoff from Developed Sites, 1995
Larry Walker Associates, June 1998, NDMP Inlet/In-Line Control Measure Study Report
Manufacturers literature
Santa Monica (City), Santa Monica Bay Municipal Stormwater/Urban Runoff Project -
Evaluation of Potential Catch basin Retrofits, Woodward Clyde, September 24, 1998
2 of 3 California Stormwater BMP Handbook January 2003
New Development and Redevelopment
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Drain Inserts MP-52
Woodward Clyde, June 11, 1996, Parking Lot Monitoring Report, Santa Clara Valley Nonpoint
I Source Pollution Control Program.
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I January 2003 California Stormwater BMP Handbook 3 of 3
New Development and Redevelopment
www.cabmphandbooks.com
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Flo-Gard+Plus Filtei
installed
LI Model No.
Inlet ID
(in x in)
Grate OD
. (in x in)
Solids Storage
Capacity (Cu ft)
Filtered Flow
(cfs)
Total Bypass
. Cap. (cfs)
FGP-12F .12 x 12 .14 x 14 .0.3 .0.4 2.8
FGP-1530F .15x30 .16x36 2.3 .1.6 6.9
FGP-16F .16 x 16 .18 x 18 .0.8 0.7 4.7
FGP-18F .18x 18 20x20 .0.8 .0.7 4.7
FGP-1822F 20 x 24 .18 x 22 2.1 1.4 5.9
FGP-1824F .16 x 22 20 x 24 .1.6 .1.2 .5.0
FGP-1836F .18 x 36 .18 x 40 2.3 .1.6 .6.9
FGP-2024F 20x 24 22x24 .1.2 .1.0 .5.9
FGP-21F 22 x 22 24 x 24 2.2 .1.5 6.1
FGP-2142F 21 x 42 26 x 42 4.3 2.4 .9.1
FGP-24F 24 x 24 26 x 26 2.2 .1.5 6.1
FGP.2436F 24 x 36 24 x 40 .3.4 2.0 8.0
FGP-2445F 24 x 45 26 x 47 4.4 2.4 .9.3
FGP-2448F 24 x48 26 x48 4.4 2.4 .9.3
FGP28F 28 x 28 .30 x 30 2.2 .1.5 6.3
FGP-30F 30 x 30 .30 x 34 .3.6 2.0 .8.1
FGP-36F 36x 36 .36 x 40 1 4.6 2.4 .9.1
FGP-3648F .36 x 48 40 x!8 . .6.8 3.2 .11.5
FGP.48F 48 x 48 48 x 52 1 .9.5 .3.9 13.2
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NOTES:
.1. Storage capacity reflects 80% of maximum solids
collection prior to impeding filtering bypass.
Filtered flow rate Includes a safety factor of 2.
Flo-Gard+Plus Catch Basin Filter inserts are available
In the standard sizes (see above) or in custom sizes.
Call for details on custom size Inserts.
A. Flo-Gard+Plus filter Inserts should be used In conjunction
with a regular maintenance proam. Refer to
maniacture?s recommended maintenance gtâdellnes.
US PATENT
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FLO-GARDTM +PLUS
CATCH BASIN FILTER INSERT
(Frame Mount)
FLAT GRATED INLET
KriStar Enterprises, Inc., Santa Rosa, CA (800) 579-8819
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Vortex Separator MP-51
Description Design Considerations
I Vortex separators: (alternatively, swirl concentrators) are gravity Service Area
separators, and in principle are essentially wet vaults. The Settling Velocity
I is
difference from wet vaults, however, is that the vortex separator
round, rather than rectangular, and the water moves in a Appropriate Sizing
centrifugal fashion before exiting. By having the water move in a Inlet Pipe Diameter
circular fashion, rather than a straight line as is the case with a
I standard wet vault, it is possible to obtain significant removal of
suspended sediments and attached pollutants with less space.
Vortex separators were originally developed for combined sewer
I overflows (CSOs), where it is used primarily to remove coarse
inorganic solids. Vortex separation has been adapted to
stormwater treatment by several manufacturers.
I California Experience
There are currently about 100 installations in California
I Advantages Targeted Constituents
May provide the desired performance in less space and L1 Sediment A • I therefore less cost.
. I1 Nutrients
May be more cost-effective pre-treatment devices than El Trash
I
traditional wet or dry basins. I1 Metals
Mosquito control may be less of an issue than with traditional Bacteria
El Oil and Grease
I El wet basins.
Organics
Limitations Legend (Removal Effectiveness)
As some of the systems have standing water that remains Low U High
I between storms, there is concern about mosquito breeding. A Medium
It is likely that vortex separators are not as effective as wet
I vaults at removing fine sediments, on the order 50 to 100
microns in diameter and less.
I . The area served is limited by the capacity of the largest
models.
I
. As the products come in standard sizes, the facilities will be
oversized in many cases relative to the design treatment
storm, increasing the cost.
I . The non-steady flows of stormwater decreases the efficiency
of vortex separators from what may be estimated or
- determined from testing under constant flow.
. Do not remove dissolved pollutants.
I January 2003 California Stormwater BMP Handbook 1 of 5
New Development and Redevelopment
www.cabmphandbooks.com
MP-51 Vortex Separator
A loss of dissolved pollutants may occur as accumulated organic matter (e.g., leaves)
decomposes in the units.
Design and Sizing Guidelines
The storniwater enters, typically below the effluent line, tangentially into the basin, thereby
imparting a circular motion in the system. Due to centrifugal forces created by the circular
motion, the suspended particles move to the center of the device where they settle to the bottom.
There are two general types of vortex separation: free vortex and dampened (or impeded)
vortex. Free vortex separation becomes dampened vortex separation by the placement of radial
baffles on the weir-plate that impede the free vortex-flow pattern
It has been stated with respect to CSOs that the practical lower limit of vortex separation is a
particle with a settling velocity of 12 to 16.5 feet per hour (o.io to 0.14 cm/s). As such, the focus
for vortex separation in CSOs has been with settleable solids generally 200 microns and larger,
given the presence of the lighter organic solids. For inorganic sediment, the above settling
velocity range represents a particle diameter of 50 to 100 microns. Head loss is a function of the
size of the target particle. At 200 microns it is normally minor but increases significantly if the
goal is to remove smaller particles.
The commercial separators applied to stormwater treatment vary considerably with respect to
geometry, and the inclusion of radial baffles and internal circular chambers. At one extreme is
the inclusion of a chamber within the round concentrator. Water flows initially around the
perimeter between the inner and outer chambers, and then into the inner chamber, giving rise
to a sudden change in velocity that purportedly enhances removal efficiency. The opposite
extreme is to introduce the water tangentially into a round manhole with no internal parts of
any kind except for an outlet hood. Whether the inclusion of chambers and baffles gives better
performance is unknown. Some contend that free vortex, also identified as swirl concentration,
creates less turbulence thereby increasing removal efficiency. One product is unique in that it
includes a static separator screen.
Sized is based on the peak flow of the design treatment event as specified by local
government.
If an in-line facility, the design peak flow is four times the peak of the design treatment
event.
a If an off-line facility, the design peak flow is equal to the peak of the design treatment event.
Headloss differs with the product and the model but is generally on the order of one foot or
less in most cases.
Construction/Inspection Considerations
No special considerations.
Performance
Manufacturer's differ with respect to performance claims, but a general statement is that the
manufacturer's design and rated capacity (cfs) for each model is based on and believed to
achieve an aggregate reduction of 90% of all particles with a specific gravity of 2.65 (glacial
sand) down to 150 microns, and to capture the floatables, and oil and grease. Laboratory tests of
2 of 5 California Stormwater BMP Handbook January 2003
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Vortex Separator MP-51
two products support this claim. The stated performance expectation therefore implies that a
lesser removalefficiency is obtained with particles less than 150 microns, and the lighter,
organic settleables. Laboratory tests of one of the products found about 60% removal of 50
micron sand at the expected average operating flow rate
Experience with the use of vortex separators for treating combined sewer overflows (CSOs), the
original application of this technology, suggests that the lower practical limit for particle
removal are particles with a settling velocity of 12 feet per hour (Sullivan, 1982), which
represents a particle diameter of ioo to 200 microns, depending on the specific gravity of the
particle. The CSO experience therefore seems consistent with the limited experience with
treating stormwater, summarized above
Traditional treatment technologies such as wet ponds and extended detention basins are
generally believed to be more effective at removing very small particles, down to the range of in
to 20 microns. Hence, it is intuitively expected that vortex separators do not perform as well as
the traditional wet and dry basins, and filters. Whether this matters depends on the particle size
distribution of the sediments in stormwater. If the distribution leans towards small material,
there should be a marked difference between vortex separators and, say, traditional wet vaults.
There are little data to support this conjecture
In comparison to other treatment technologies, such as wet ponds and grass swales, there are
few studies of vortex separators. Only two of manufactured products currently available have
been field tested. Two field studies have been conducted. Both achieved in excess of 8o%
removal of TSS. However, the test was conducted in the Northeast (New York state and Maine)
where it is possible the stormwater contained significant quantities of deicing sand.
Consequently, the influent TSS concentrations and particle size are both likely considerably
higher than is found in California stormwater. These data suggest that if the stormwater
particles are for the most part fine (i.e., less than 50 microns), vortex separators will not be as
efficient as traditional treatment BMPs such as wet ponds and swales, if the latter are sized
according to the recommendations of this handbook.
There are no equations that provide a straightforward determination of efficiency as a function
I of unit configuration and size. Design specifications of commercial separators are derived from
empirical equations that are unique and proprietary to each manufacturer. However, some
general relationships between performance and the geometry of a separator have been
I developed. CSO studies have found that the primary determinants of performance of vortex
separators are the diameters of the inlet pipe and chamber with all other geometry proportional
to these two.
I Sullivan et al. (1982) found that performance is related to the ratios of chamber to inlet
diameters, D2/D1, and height between the inlet and outlet and the inlet diameter, Hi/Di, shown
in Figure 3. The relationships are: as D2/D1 approaches one, the efficiency decreases; and, as I the Hi/Di ratio decreases, the efficiency decreases. These relationships may allow qualitative
comparisons of the alternative designs of manufacturers. Engineers who wish to apply these
concepts should review relevant publications presented in the References.
I Siting Criteria
There are no particularly unique siting criteria. The size of the drainage area that can be served
I by vortex separators is directly related to the capacities of the largest models.
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MP-51 Vortex Separator
Additional Design Guidelines
Vortex separators have two capacities if positioned as in-line facilities, a treatment capacity and
a hydraulic capacity. Failure to recognize the difference between the two may lead to significant
under sizing; ie., too small a model is selected. This observation is relevant to three of the five
products. These three technologies all are designed to experience a unit flow rate of about 24
gallons/square foot of separator footprint at the peak of the design treatment event. This is the
horizontal area of the separator zone within the container, not the total footprint of the unit. At
this unit flow rate, laboratory tests by these manufacturers have established that the
performance willmeet the general claims previously described. However, the units are sized to
handle 100 gallons/square foot at the peak of the hydraulic event. Hence, in selecting a
particular model the design engineer must be certain to match the peak flow of the design event
to the stated treatment capacity, not the hydraulic capacity. The former is one-fourth the latter.
If the unit is positioned as an off-line facility, the model selected is based on the capacity equal
to the peak of the design treatment event.
Maintenance
I Maintenance consists of the removal of accumulated material with an eductor truck. It may be
necessary to remove and dispose the floatables separately due to the presence of petroleum
product.
I Maintenance Requirements
Remove all accumulated sediment; and litter and other floatables, annually, unless experience
I indicates the need for more or less frequent maintenance.
Cost
I Manufacturers provide costs for the units including delivery. Installation costs are generally on
the order of 50 to 100 % of the manufacturer's cost. For most sites the units are cleaned
annually.
Cost Considerations
The different geometry of the several manufactured separators suggests that when comparing
I the costs of these systems to each other, that local conditions (e.g., groundwater levels) may
affect the relative cost-effectiveness.
References and Sources of Additional Information
I Field, R., 1972, The swirl concentrator as a combined sewer overflow regulator facility, EPA/R2-
-oo8, U.S. Environmental Protection Agency, Washington, D.C.
I Field, R., D. Averill, T.P. O'Connor, and P. Steel, 1997, Vortex separation technology, Water
Qual. Res. J. Canada, 32, 1, 185
Manufacturers technical materials
Sullivan, RH., et al., 1982, Design manual— swirl and helical bend pollution control devices,
I EPA-600/8-82/013, U.S. Environmental Protection Agency, Washington, D.C.
Sullivan, RH., M.M. Cohn, J.E. Ure, F.F. Parkinson, and G. Caliana, 1974, Relationship between
diameter and height for the design of a swirl concentrator as a combined sewer overflow I regulator, EPA 670/2-74-039, U.S. Environmental Protection Agency, Washington, D.C.
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Vortex Separator MP-51
Sullivan, R.H., M.M. Cohn, J.E. lJre, F.F. Parkinson, and G. Caliana, i, The swirl
I concentrator as a grit separator device, EPA670/2-74-026, U.S. Environmental Protection
Agency, Washington, D.C.
I Sullivan, RH., M.M. Cohn, J.E. Ure, F.F. Parkinson, and G. Caliana, 1978, Swirl primary
separator device and pilot demonstration, EPA600/2-78-126, U.S. Environmental Protection
Agency, Washington, D.C.
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Targeted Constituents
ll Sediment A
[1 Nutrients
tEl Trash I
Metals A
Bacteria
Oil and Grease A
tEl Organics A
Oxygen Demanding A
Legend (Removal Effectiveness)
• Low • High
A Medium
Vegetated Swale TC-30
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General Description
Vegetated swales are open, shallow rhannels with vegetation
rovering the side slopes anil bottom that collect and slowly
onvey runff flow to dow:stream discharge points. They are
designed to treat runoff through filtering by the vegetation in the
channel, filterbg through a subsoil matrix, arid/or infiltration
into the underlying soils. S wales can be natural or manmade.
They trap particulate pollL:ants (suspended solids and trace
metals), promcte inliltrati: n, and reduce the flow veic city of
stormwater runoff. VegetiJied swales can serve as pan of a
stormwater drainage system and can replace curbs, guters and
storm sewer systems. Therefore, swales are best suited for
residential, inistria1, and commerrial areas with low flow and
smaller populaions.
Inspection/Maintenance Considerations
It is important to consider :hat a thick vegetative cover is needed
for vegetated sivales to function properly. UuaIlv, swales
require little nnre than ncrmal lancscape maintenance activities
such as irrigati 1)11 and mowing to maintain pollutant removal
efficiency. Swales can bee :me a nuisance du to mosquito
reedin in standing water if obstructions develop (e.g., debrli
accumulation, mvasive vegetation) and/or if proper drainage
slopes are not implemented and maintained. The application of
fertilizers and pesticides sould be minimized.
Maintenance Concerns,
Objectives, and Goals
. Channelization
VegetatiorVLandscape
Maintenance
Vector Control
Aesthetics
Hydraulic and Removal Efficacy
AA
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TC-30 Vegetated Swale
[Inspection Activities Suggested
Frequency
Inspect after seeding and after first major storms for any damages. Post construction
Inspect for signs of erosion, damage to vegetation, channelization of flow, debris and Semi-annual
litter, and areas of sediment accumulation. Perform inspections at the beginning and end
of the wet season. Additional inspections after periods of heavy runoff are desirable.
Inspect level spreader for clogging, grass along side slopes for erosion and formation of Annual
rills or gullies, and sand/soil bed for erosion problems.
Suggested
FMaintenance Activities Frequency
Mow grass to maintain a height of 3-4 inches, for safety, aesthetic, or other purposes. As needed
Litter should always be removed priorto mowing. Clippings should be composted. (frequent,
seasonally)
Irrigate swale during dry season (April through October) or when necessary to maintain
the vegetation.
Provide weed control, if necessary to control invasive species.
Remove litter, branches, rocks blockages, and other debris and dispose of properly. Semi-annual
Maintain inlet flow spreader (if applicable).
Repair any damaged areas within a channel identified during inspections. Erosion rills or
gullies should be corrected as needed. Bare areas should be replanted as necessary.
Declog the pea gravel diaphragm, if necessary. Annual (as needed)
Correct erosion problems in the sand/soil bed of dry swales.
Plant an alternative grass species if the original grass cover has not been successfully
established. Reseed and apply mulch to damaged areas.
Remove all accumulated sediment that may obstruct flow through the swale. Sediment As needed
accumulating near culverts and in channels should be removed when it builds up to 3 in. (infrequent)
at any spot, or covers vegetation, or once it has accumulated to 10% of the original design
volume. Replace the grass areas damaged in the process.
Rototill or cultivate the surface of the sand/soil bed of dry swales if the swale does not
draw down within 48 hours.
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Additional. Information
I Recent research (Colwell et al., 2000) indicates that grass height and mowing frequency have
little impact on pollutant removal. Consequently, mowing may only be necessary once or twice a
year for safety or aesthetics or to suppress weeds and woody vegetation.
References
Metropolitan Council, Urban Small Sites Best Management Practices Manual. Available at:
http: ILwww.metrocouncil.oLglenvironment/Watershed/BMP.Lmanual.htm
U.S. Environmental Protection Agency, Post-Construction Stormwater Management in New
Development & Redevelopment BMP Factsheets. Available at:
cfpub.epa.gov/updes/stormwater/menuofbmpslbmp files.cfm
Ventura Countywide Stormwater Quality Management Program, Technical Guidance Manual
for Stormwater Quality Control Measures. July, 2002.
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APPENDIX C
Ii DRAINAGE NARRATIVE
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CONSULTING
August 1, 2007 JN 55-100221.026
Engineering Department
City of Carlsbad
1635 Faraday Avenue
Carlsbad, CA 92008
Subject: Drainage Summary for Planning Area #3— Building 10 Parcel Map at the La
Costa Resort & Spa
To Whom It May Concern:
The proposed development for the Planning Area #3 - Building 10 project located at La Costa
Resort, proposes one building and one parking lot. This area was designated as a surface
parking lot in the current Master Plan, but will be entitled for the proposed building with a Master
Plan Amendment and associated PUD.
This project will not significantly alter drainage patterns as those depicted in the "Drainage Study
for La Costa Resort and Spa" (Hunsaker Associates San Diego, Inc., Sept. 2006), nor adversely
effect runoff quantities since pre and post development "C" factors are the same. Therefore, this
project should not require a drainage report. Should you have any questions or comments
regarding this issue, please call (760) 603-6243.
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Timothy M. Thiele, P.E.
Project Engineer
C60283
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H:\PDATA\55100221\Admin\correspndnc\221 ItO05ViIla5130rainage.doc
PLANNING 10 DESIGN 16 CONSTRUCTION
5050 Avenida Encinas, Suite 260, Carlsbad, CA 92008-4386 U 760476.9193 • Fax 760.476.9198
Offices located throughout California, Arizona & Nevada • www.RBEcom
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APPENDIX D
1 APPROVED STORM WATER MANAGEMENT PLAN
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STORM WATER MANAGEMENT PLAN FOR
LA COSTA RESORT AND SPA - MASTER PLAN AMENDMENT
JOB NO. 14107-L
MAY 29 2003
REVISED: OCTOBER 29, 2003
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STORM WATER MANAGEMENT PLAN
FOR
LA COSTA RESORT AND SPA - MASTER PLAN AMENDMENT (CITY OF CARLSBAD MASTER PLAN.A1VIENDMENT)
JOB NO. 14107-L
MAY 2, 2003
REVISED OCTOBER 29, 2003
RED
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EXP- 3/di/06
CIVIL
CA
Roger L. Ball ROE 27678
Prepared By:
Rick Engineering Company
5620 Friars Road
San Diego, California 92110
(619) 291-0707
a
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TABLE OF CONTENTS
PAGES
VICINITYMAP ............................................................................................................................1
INTRODUCTION......................................................................................................................... 2
PROJECTDESCRIPTION ............................................................................................................ 3
POLLUTANTS AND CONDITIONS OF CONCERN ................................................................ 5
PERMANENT STORM WATER BEST MANAGEMENT PRACTICES ................................. 6
OPERATION AND MAINTENANCE PLAN .................................................................... ............ 8
SUMMARY..................................................................................................................................
APPENDICES
STORM WATER REQUIREMENT APPLICABILITY CHECKLIST
TABLES FROM THE CITY OF CARLSBAD STORM WATER STANDARDS
MANUAL
CALCULATIONS FOR ONSITE WATER QUALITY TREATMENT FLOW
REQUIREMENTS AND WATER QUALITY TREATMENT PRODUCT
INFORMATION
MAP POCKETS
1. WATER QUALITY SITE PLAN EXHIBIT FOR LA COSTA RESORT- AND SPA MASTER PLAN AMENDMENT
May 1, 2003
Revised: November 3, 2003
RC:rh\14107\Study\Water Quality Impact Master Plan (002)
CITY OF OCEANSIDE
CITY OF VISTA.
CITY OF
SAN MARC.O:S
'LT TO SCALE
- PACtEl-C
OCEAN
liON
CITY. OF ENCINITAS 1c
VICINITY MAP
NOT TO SCALE
May 1, 2003
1 Revised: November 3, 2003
RC:rh\14107\Study\water Quality Impact Master Plan (002)
INTRODUCTION
I
This Storm Water Management Plan (SWvtP) describes the permanent Storm Water Best
I Management Practice (BMPs) recommended to be implemented for the La Costa Resort and Spa
Master Plan Amendment project, that satisfy the requirements identified in the following
documents:
State Water Resources Control Board (SWRCB) Order No. 99-08-DWQ, National
I Pollutant Discharge Elimination System (NPDES) General Permit No. CAS 000002 for
Discharges of Storm Water Runoff Associated With Construction Activity.
I • San Diego Region Municipal NPDES Storm Water Permit, Order Number 2001-01
(Municipal Permit).
I .. City of Carlsbad Standard Urban Storm Water Mitigation Plan' (SUSMP), Storm Water
I Standards Manual dated April 2003.
Included in this report are the preliminary storm runoff calculations necessary to size the
I proposed BMPs, the BMP sizing calculations, technical information for the proposed BMPs and
a discussion on the operation and maintenance requirements for the permanent BMPs.
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May 1, 2003 I 2 Revised: November 3, 2003 RC:rh\14107\Study\Water Quality Impact Master Plan (002)
PROJECT DESCRIPTION
This SWMP has been prepared for the La Costa Resort and Spa Master Plan Amendment project.
The project site is located in the City.of Carlsbad, northeast of Batiquitos Lagoon. The site is
bounded by El Camino Real to the west, Arenal Road to the north and San Marcos Creek to the
south (see Site Plan Exhibit in Map Pocket).
The project proposes to add 190 Resort Villa Units with additional parking, both at grade and
subterranean, and pedestrian pathways to the existing Resort facilities.
Conveyance of Site Runoff- Existing Condition
Prior to the recent construction of the new Spa facility, runoff from the areas to the north and east
of the new Ballroom facility (CUP 258(c))was conveyed, via surface flow, southerly down
Estrella De Mar Road, onto and westerly down Costa Del Mar Road, where it was collected into
three curb inlets adjacent to El Camino Real. Storm runoff collected into these inlets is then
routed, southerly, through an existing 36-inch RCP storm drain which discharges into San
Marcos Creek. Runoff from the westerly portion of the project site is conveyed southerly, via
surface flow, through an existing swale to an existing inlet structure located northeast of the
intersection of El Camino Real and Costa Del Mar Road. Runoff collected into this inlet.
structure is routed westerly through an existing 36-inch CMP storm drain, under El Camino Real,
and is discharged on the west side of El Camino Real.
Conveyance of Site Runoff - Developed Condition
Surface runoff from the proposed Resort Villa areas will be conveyed, via surface flow, to a
series of private inlets/catch basins. Runoff from the surface parking areas will also be collected
into a series of private inlets located within the paved areas. Runoff collected into these private
inlets/catch basins, will be conveyed southerly through a private underground storm drain
system, running west of the proposed Ballroom (per CUP 258(c)) to a storm water pollution
control unit to be located, southwest of the new Ballroom facility. Discharge from the storm
water pollution control unit will be conveyed to a storm water diversion structure which will
May 1, 2003
3 Revised: November 3, 2003
RCrh\l4107\Study\ Water Quality Impact Master Plan (002)
serve to discharge storm runoff into the 36-inch RCP public storm drain system (crossing under
El Camino Real), located northeast of the intersection of El Carnino Real and Costa Del Mar
Road' and the existing storm drain system located at the westerly end of Costa Del Mar Road.
May I, 2003 4 Revised: November 3, 2003
RC:rh\14 107\Study\ Water Quality Impact Master Plan (002)
POLLUTANTS AND CONDITIONS OF CONCERN
Per the San Diego Region Municipal Permit and the City of Carlsbad Storm Water Standards, the
La Costa Resort and Spa Master Plan Amendment project falls under the following priority
project category: "Commercial Development greater than, or equal to 100,000 Ft2, and 'Parking
lots greater'than or equal to 5,000 square feet or with at least 15 parking spaces, and potentially
exposed to urban runoff." According to the City of Carlsbad Storm Water Standards Table 1 -
"Standard Development Project and Priority Project Storm Water BIvIP Requirements Matrix"
(Appendix B), this project is required to provide site design BMPs, source control BMPs, BMPs
applicable to individual priority project categories, and treatment control BMPs.
According to Table 2 - Anticipated and Potential Pollutants Generated by Land Use Type
(Appendix B), anticipated pollutants for the specified project categories include: heavy metals,
trash & debris, and oil & grease. The potential pollutants include sediments, nutrients, organic
compounds, oxygen demanding substances, bacteria and viruses, and pesticides.
According to the "San Diego Region Water Quality Control Board (SDRWCB) Plan for the San
Diego Basin (9)", dated September 8, 1994, the.La Costa Resort and Spa Master Plan
Amendment project is within the Batiquitos Hydrologic Sub-Area of the San Marcos Hydrologic
Area of the Carlsbad Hydrologic Unit. The corresponding basin number designation is 904.51.
The San Marcos Hydrologic Area is listed.under section 303(d); list of impaired waters., of the
Clean Water Act, as an impaired water body. The San Marcos Creek is 303(d) listed for colifoim
bacteria.
Conditions of concern for the project are related to any relevant hydrologic and environmental
factors including the property's percent of impervious erosion area and infrastructure drainage
features that are to be protected specific to the project area's watershed.
May 1, 2003 5 Revised: November 3, 2003
RC:rh\l4l07\StudWater Quality Impact Master Plan (002)
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PERMANENT STORM WATER BEST MANAGEMENT PRACTICES
The Municipal Permit and the City Storm Water Standards require the implementation of
applicable site design, source control, project specific, and treatment control BMPs. To meet
these requirements, the project will incorporate a series of non-structural and structural BMPs to
the maximum extent practicable (MEP).
A detailed description of each type of BMP is discussed below:
Site Design BMPs
The following site design BMPs have been applied:
Minimize the impervious footprint by increasing building density while decreasing
building footprint.
Minimize directly connected impervious areas to the maximum extent practicable.
Avoid draining water over tops of slopes in order to minimize erosion.
Source Control BMPs
Source control BMPs are generally non-structural and are intended to reduce the quantity of
pollutants entering the storm drain system.' The following source control BMPs are proposed to
be utilized for the La Costa Resort and Spa Master Plan Amendment project:
Trash storage areas to be paved with an impervious surface, designed to' prevent
offsite transport of trash.
Pest resistant plants will be planted to reduce the need for pesticides.
An efficient irrigation system will be installed within the landscaped areas that
addresses the specific 'water-requirements for-those landscaped areas.
Concrete stamping or stenciling of inlets and catch basins.
Distribution integrated pest management education materials to future site tenants.
- May l,2003 6 , Revised: November 3, 2003 RC:rh\ 14I07\Study Water Quality Impact Master Plan (002)
BMPs Applicable to Individual Priority Project Categories
The City's Storm Water Standards Manual, Table I (Appendix B), requires specific BMPs be
applied, where applicable, if theproj ect includes dock areas, maintenance bays, vehicular wash
areas, outdoor processing areas and/or surface parking areas. The La Costa Resort and Spa
Master Plan Amendment project includes surface parking areas. The following requirement will
be incorporated into the project:
Where landscaping is proposed in surface parking areas, the landscaped areas will be
incorporated into the drainage design.
Treatment Control BMPs
Treatment control BMPs are required to infiltrate, filter, and/or treat runoff from the project
footprint to one of the "numeric sizing treatment standards" listed in the City's Storm Water
Standards Manual, Table 3 (Appendix B). To fulfill this requirement, this project intends to treat
the site runoff by means of Bio-Clean filter inserts placed in the three private inlets.proposed for
the project and the three existing inlets located at the westerly end of Costa Del Mar Road.
These inserts are designed to reduce and contain petroleum hydrocarbons, pesticides, sediment,
debris and trash from the runoff. In addition to the inserts, an in-line storm water treatment unit
will be installed. A CDS Technologies storm water treatment unit will be used on this project.
Storm Water Treatment Units are mechanical separators that physically reduce sediment, trash,
debris, and oil and grease, from the flow and pesticides that attach to sediment. Refer to
Appendix C for the flow and pesticides that attach to sediment. Refer to Appendix C for the
flow based numeric sizing calculations and details of the specified Bio-Clean inserts and CDS
Technologies Storm Water Treatment Unit.
The Bio-Clean inserts are considered drainage inserts. Per the City's Storm Water Standards
Manual, Table 5 (Appendix B), drainage inserts rank low to medium in removal efficiency for
the project's pollutants of concern. The storm water treatment unit is considered a hydrodynamic
separator system. Per Table 4 (Appendix B), hydrodynamic separator systems rank low to
medium in removal efficiency for the project's pollutants of concern.
May I, 2003 7 Revised: November 3, 2003
RC:rh\14l07Study\ Water Quality Impact Master Plan (002)
OPERATION AND MAINTENANCE PLAN
KSL La Costa Resort Corporation, a Delaware corporation, will construct the improvements
proposed for thô La Costa Resort and Spa Master Plan Amendment and shall be required to
maintain all BMPs on the site.
The site shall be kept in a neat and orderly fashion with a regularly scheduled landscape
maintenance crew in charge of keeping gutters. and inlets free of litter and debris. The landscape
crew will also maintain the landscaping to prevent soil erosion and minimize sediment transport.
Inlet stamps shall be inspected and reapplied as needed.
The project consists of three proposed and three existing type 'B' curb inlets, which will include
bio-clean filter inserts. Bio-Clean Environmental Services recommends replacement of the
hydrocarbon absorption boom four times. per year. Currently the approximate cost to replace
each boom is $80.00. This amounts to a maintenance cost of approximately $320.00 per year,
per inlet.
The proposed project will utilize one CDS Technologies Storm Water Treatment Unit.
Currently, the approximate maintenance cost for one CDS Technologies Unit is $4,500.00 per
year which includes $300.00' per hour for labor with a 4-hour minimum and a $300.00 waste
disposal fee per maintenance service for the unit. The maintenance cost assumes that the CDS
Technologies Units are serviced three times a year. These are preliminary costs.
KSL La Costa Resort Corporation shall retain maintenance records of at least 5-years, which
shall be made available to the City of San Diego for inspection upon request. -
May 1, 2003 8 Revised: November 3, 2003
RC:rh\t 4 t07\S tudy\ Water Quality Impact Master Plan (002)
SUMMARY
The La Costa Resort and Spa Master Plan Amendment project will conform to applicable
NTPDES requirements. The City of Carlsbad SUSMP/Storm Water Standards Manual establishes
that a rainfall intensity of 0.2 in./hr. must be treated. Based on this criterion, the completed
project will require approximately 4 cfs of runoff to be treated, infiltrated or filtered. The project
intends to treat this runoff with installation of a Bio-Clean filter insert within each type 'B' curb
inlet, and the construction of an in-line CDS Technologies Storm Water Treatment Unit. The
filter insert is designed to reduce and contain, at a level considered low to medium in removal
efficiency (Carlsbad Storm Water Standards Manual, Table 4), petroleum hydrocarbons,
pesticides, sediment, debris, and trash from the runoff. The storm water treatment units are
designed to physically reduce sediment, trash, debris, and oil and grease from the flow and
pesticides that attach to sediment. The filter insert and storm water treatment units are sized
using flow-based numeric sizing criteria to meet the requirements of the Storm Water Standards
('which covers- both the- Municipal Storm Water Permit and -the City SVSMF' uitem- n.t). The
completed project will also incorporate various concepts of non-structural and structural BMPs
that include property owner education, stenciled inlets, and landscaping.
May I, 2003 9 Revised: November 3, 2003
RC:rh\14107\Study\Water Quality Impact Master Plan (002)
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APPENDIX A
STORM WATER REQUIREMENTS APPLICABILITY CHECKLIST
Storm Water Staridards
4/03/03
APPENDIX A
STORM WATER REQUIREMENTS APPLICABILITY CHECKLIST
Complete Sections 1 and 2 of the following checklist to determine your project's
permanent and construction storm water best management. practices requirements.
This form must be completed and submitted with your permit application.
Section 1. Permanent Storm Water BMP ReqUirements:
If any answers to Part A are answered "Yes," your project is subject to the "Priority
Project Permanent Storm. Water. BMP Requirements," and "Standard Permanent Storm
Water BMP Requirements" in Section III, "Permanent Storm Water BMP Selection
Procedure" in the Storm Water Standards manual.
If all answers to Part A are "No," and any answers to Part B are "Yes," your project is
'only subject to the "Standard Permanent Storm Water BMP Requirements". If-every question' in Part A and B is answered "No," your project is exempt from permanent
storm water requirements.
Part A: Determine Priority Proiect Permanent Storm Water BMP Reauirements.
Does the project meet the definition of one or more of the priority project
Yes categories?* ' No I
Detached residential development of 10, or more units
Attached residential development of 10 or more units CommerOial development greater than 100,000 square feet
Automotive repair shop.
Restaurant . Steep hillside development greater than 5,000 square feet
Project discharging to receiving waters within Environmentally Sensitive Areas
S Parking lots greater than or equal to5,00Q ft or with at least 15 parking spaces, 'and
potentially, exposed to urban runoff
9. Streets, roads; highways, and freeways which would. create-a new paved surface that is
5,.0O.Q,.sq.uare.feet. or, greater . . . * Refer to the definitions section in the Storm Water Standards for expanded definitions of the priority project categories.
Limited Exclusion: Trenching and resurfacing work associated with utility projects are not considered
priority projects. Parking lots, buildings and other structures. associated with utility projects are
priority projects if one or more of the criteria in Part A is met. If all answers to Part A are No",
continue to Part B.
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4/03/03
Part B: Determine Standard Permanent Storm Water Recuirements.
Does the project propose:
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Yes No
New impervious areas, such as rooftops, roads, parking lots, driveways, paths and
sidewalks?
New _pervious _landscape _areas _and _irrigation _systems?
Permanent structures within 100 feet of any natural water body?
Trash storage areas?
.. . Liquid solid
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_or_ _material _loading _and _unloading _areas? _. j Vehicle or equipment fueling, washing, or maintenance areas?
Require a General NPDES Permit for Storm Water Dischares Associated with
Industrial Activities (Except construction)?*
Commercial or industrial waste handling or storage, excluding typical office or
household waste?
9.. Any grading or ground disturbance during construction?
. X 10. Any alteration storm. I
_new _storm _drains, _or _to_existing_ _drains? *10 find out if your project.is required to obtain an individual General NPDES Permit for Storm Water
Discharges Associated with Industrial Activities, visit the State Water Resources Control Board web
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at, www.swrcb.ca.gov/s.tormwtr/industrial.html
Section 2. Construction Storm Water BMP Requirements:
If the answer 10 question 1 of Part C is answered "Yes," your project is subject to Section IV, "Construction Storm Water BMP Performance Standards," and must prepare
a Storm Water Pollution Prevention Plan (SWPPP). If the answer to question 1 is "No,"
but the answer to any of the.remaining questions is "Yes," your project is subject to
Section IV, "Construction Storm Water BMP Performance Standards," and must prepare
a Water Pollution Control Plan (WPCP). If every question in Part C is answered "No,"
your project is exempt from any construction storm water BMP requirements.. If any of
the answers to the questions in Part C are "Yes," complete the construction site
prioritization in Part 0, below.
Part C: Determine ConstrUction Phase Storm Water Reauirements.
Would the project meet any of these criteria during construction? Yes No
Is the project subject to California's statewide General NPDES Permit fo Storm Water
Discharges Associated With ConstructiorrAOtivities?
Does the project propose grading or soil disturbance?
Would storm water or urban runoff have the potential to contact any portion of the
consfruction area, including washing and staging areas?
Would the project use any construction materials that could negatively affect water
quality if discharged from the site (such as, paints, solvents, concrete, and
stucco)?
.
31
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 pose a 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.]
A) High Priority
Projects where the site is 50 acres or more and gradihg 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
I
Projects, active or inactive, adjacent or tributary to sensitive water bodie
D B) Mediuth 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.)
Permit projects in the public right-of-way where grading occurs, such a5
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.
D 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 walls, single-family homes, small tenant
improvements, etc.
32
I:!
[A
APPENDIX B
TABLES FROM THE STORM WATER STANDARDS MANUAL
ve
Storm Water Standards 4/03/03
Table 1. Standard Development Project & Priority Project Storm Water BMP Requirements Matrix.
BMPs Applicable to Individual
PrioryProject Categories(J)
CU
ca
CU cn.ca ff
• >. . o C < ,, Q)
- en C6 U, () — cc CL) CL a E° c
- = •-
Site Source Cn LL. Treatment
Design Control . . . . . Control
BMPs(11 BMPs(2) ° BMPs(4)
• Standard Projects R R 0 0 0 .0 0 0 0 0 0 0
I 1'0 1.
Priority Projects:
Detached Residential
• R R R R R S Development
Attached Residential R R -- Development
Commercial Development R R R R R R S >100000ft2
Automotive Repair Shop • R R R R R R R S
Restaurants R R R R S
Hillside Development R R R R S >5,000ft2
-- - Parking Lots R R R(5) 'S
• Streets, Highways & R R Freeways
• R = Required; sielect one or more applicable and appropriate BMPs from the applicable steps in Section 111.2.A-D, or equivalent as identified in Appendix C.
0 = optionall.or may be required by City staff. As appropriate, applicants are encouraged to incorporate treatment control
"M s
and BMPs applicable to individual priority,project categories into-the project design. City staff may require one or
more of these BMPs, where appropriate.
• S Select one or more applicable and appropriate treatment control BMPs from Appendix C.
Refer to Section 1112.A.
Refer to Section lll.2.B.
Priority project categories must apply specific storm water SMP requirements, Where applicable. Priority projects are subject to the requirements of all priority project categories that apply.
• Refer to Section 111.2.0.
Applies if the paved area totals >5,000 square feet or with >15 parking spaces and is potentially exposed to'urban runoff.
LV
Storm Water Standards
4/03/03
When referred to this Section, by Step 2 of, Section U, complete the analysis required for
your project in the subsections of Section 111.1 below.
1. IDENTIFY POLLUTANTS & CONDITIONS OF CONCERN.
A. Identify Pollutants from the Project Area
Using Table 1, identify the project's anticipated pollutants. Pollutants associated with
any hazardous material sites that have been remediated or are not, threatened by the
proposed project are not considered a pollutant of concern. Projects meeting the
definition of more than one project category shall identify all general pollutant categoris that apply.
Table 2 AnticiratRd and Potential Pollutants Grrated by Land Use Tvr,e
GenerI Pollutant Categories
Project'
•
' Trash Oxygen Bacteria
- Categories Heavy Organic & Demanding Oil & & Sediments Nutrients Metals Compounds Debris Substances Grease Viruses Pesticides Detached
Residential X X S X X X. , X ' X Development
'Attached '
Residential X X
' X P11) (2) (1) , x Development
Commercial
. Development P( PfJ (2) , X P( X P11 ' (5) >100,0001t2 S
Automotive
Repair X X(4)(5)' X ' , X
ReVa'urants X ' X , X X
Hillide
' Development X X ,, X ' X X X >5,000.ft2 '
Parking Lots ' P(t) (1) x , ' , X ' p(1) X (1J
Streets,
Highways & X P1 X X(4) X (5) X Freeways
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.
.,
12
Storm Water Standards
4/03/03
I awe S. Numeric iizing I reatment litandards.
Volume
VolUme-based BMPs- shall be designed to mitigate (infiltrate, filter, or treat) the volume of runoff
produced from a 24-hour 85th percentile storm event, as determined from isopluvial maps
contained in the County of San Diego Hydrology Manual.
OR
'1
Flow
Flow-based BMPs shall be designed to mitigate (infiitrate filter, or treat) the maximum flow rate
of runoff produced from a rainfall intensity of 0.2 inch of rainfall per hour for each hour of a storm
event.
1. Structural Treatment BMP Selection Procedure
Priority projects shall select a single or combination of treatment BMPs from the
categories in Table 4 that maximize pollutant removal for the particular pollutant(s) of
concern. Any pollutants the project is expected to generate that are also causing a
Clean Water Act section 303(d) impairment of the downstream receiving waters of the
project should be given top priority in selecting treatment BMPs.
To select a structural treatment BMP using the StrUctural Treatment Control BMP
Selection Matrix (Table 4), each priority project shall • compare the list of pollutants for which the downstream receiving waters are impaired (if any). According to the 18
303(d) listing, the Agua Hedionda Lagoon is impaired. for sediment and siltation. Buena
71 Vista Lagoon also has impaired beneficial uses (aquatic life) due to high
sedimentation/siltation. Portions of Carlsbad where construction sites have the potential
to discharge into a tributary of a 303(d) or directly into a. 303(d) ate pdyo sites . 1öt FTTèihtáon. These water bodies include the Pacific Ocean, Buena Vista Lagoon, Encinas Creek, Agua Hedionda
Lagoon, and Batiquitos Lagoon.
Priority projects that are not anticipated to generate a pollutant for which the receiving
water is Clean Water Act Section 303(d) impaired shall select a single or combination of
. structural freatment BMPs from Table 4 that are effective for pollutant removal of the identified pollutants of concern determined to be most significant for the project.
Selected BMPs must be effective for the widest range of pollutants of concern anticipated to be generated by a priority project (as.ideñtified in Table 1).
Alternative storm water BMPs not identified in Table 4 may be approved at the
discretion of the City Engineer, provided the alternative BMP is as effective in removal of pollutants of concern as other feasible BMPs listed in Table 4.
20
Storm Water Standards
4/03/03
Table 4. Structural Treatment Control BMP Selection Matrix.
Pollutant of Concern
- Treatment Control BMP Categories
Biofllters Detention]
Basins
Infiltration
L Basins(1)
Wet Ponds or
I Wetlands
Drainage
Inserts Filtration Hydrodynamic
Separator Systems(2) Sediment M H H H L H M Nutrients L M M M L M L Heavy Metals M M M H L H L Organic Compounds U 1. U U U L J M I L Trash & Debris L I H I U f U M I H I M Oxygen Demanding
Substances I L- M M M L M L Bacteria U U _U L M _L OiI& Grease M 'M
_H
_U L- H 'Pesticides U -U
_U
_U _U _L _L
U _L (1) Including trenches and porous pavement
(2) Also known as hydrodynamic devices' and baffle boxes.
Low removal efficiency Medium removal efficiency
H: High removal efficiency
U: Unknown removal efficiency
'Sources: Guidance Speciijing Management Measures for Sources of Nonpoint Pollution in Coastat Waters (1993), National Stomiwater Best Manaoement Practices Database (2001). and Guide for BMP Selection in 'Urban Develooed Areas (2001).
Y. Restrictions on the Use of Infiltration Treatment BMPs
31. Treatment control BMPs that are designed to primarily function as infiltration
devices shall meet the following conditions (these conditions do not apply to treatment BMPs which allow incidental infiltration and are not designed to primarily
function as infiltration devices, such as grassy swales, detention basins, vegetated
buffer strips, constructed wetlands, etc.): (1) .urban runoff from. commercial developments shall undergo pretreatment to remove both physical and chemical
contaminants, such as sedimentation or filtration, prior to infiltration; (2) all dry,
weather flows shall be diverted from infiltration devices except for those non-storm
water discharges authorized pursuant to 40 CFR 122.26(d)(2)(iv)(8)(1): diverted
stream flows, rising ground waters, uncontaminated ground water infiltration [as
defined at 40 CFR 35.2005(20)] to storm water conveyance systems,
uncontaminated pumped ground water, foundation drains, springs, water from
crawl space pumps, footing drains, air conditioning condensation, flow from
riparian habitats and wetlands, waterline flushing, landscape irrigation, discharges
from potable water sources other than water main breaks, irrigation water,
individual residential car washing, and dechlorinated swimming pool discharges;
(3) pollution prevention and source control BMPs shall ,be implemented at a level'
appropriate to protect groundwater quality at sites where infiltration structural
treatment BMPs are 'to be used; (4) the vertical distance from the base of any
infiltration 'structural treatment BMP to the seasonal high groundwater mark shall
be at least 10 feet. Where groundwater does not support beneficial uses, this
vertical distance criterion may be reduced, provided groundwater quality is
maintained; (5) the soil through which infiltration is to occur shall have physical and
21
APPENDIX C
CALCULATIONS FOR ONSITE WATER QUALITY TREATMENT FLOW
REQUIREMENTS AND TREATMENT PRODUCT INFORMATION
I
I
s FLOW BASED NUMERIC SIZING CALCULATIONS
The structural treatment BMIPs for the La Costa Resort and Spa Master Plan Amendment project
I
will be sized using flow based criteria per the City's Storm Water Standards Manual, Table 3.
This criteria states that the "flow based BMPs shall be designed to mitigate (infiltrate, filter or
treat) the maximum flow rate of runoff produced from a rainfall intensity of 0.2 inch of rainfall
I r per hour." Structural BMP sizing calculations are as follows:
Bio-Clean Filters
S
I ' Per the manufacturers specifications (see calculations, this Appendix), one Bio-Clean filter is
capable of treating a runoff flow of 0.35 cfs based on the above described area. Therefore the
I
maximum surface area that can be effectively treated by one Bio-Clean Filter is 5 acres, per the following calculations:
I Q=CIA, therefore A=Q/CW; Q=0.85 cfs, 1=0.2 in/hr, and assuming a con:imèrcial runoff
coefficient, C, of 0.85
A0.85/085 (0.2)=5.0 acres.
Per the attached site BMP/Basin Area Exhibit (see Map Pocket) the two existing inlets located at
node 620 (per the La Costa Resort and Spa Master Plan Drainage Study, dated November 3, 2003) collect runoff from the largest contributing area of 8.3 acres (this area is conservative in
that it includes some landscaped area which will be picked up by the private underground storm
drain system). Per the calculation above, the Bio-Clean inserts to be installed in these two
existing inlets will be able to treat a combined maximum area of 10 acres and will therefore have
sufficient capacity to treat the runoff from this area. The contributing area to each of the
remaining four Type B inlets ('located at nodes 510, 540, 541 and 621 per the attached Site BMP/Basin Area Exhibit) is less than 5 acres. Therefore the Bio-Clean inserts to be installed in
these inlets will' also have sufficient capacity to 'treat the surface runoff within each area.
CDS Technolo ales Storm Water Treatment Unit
Per the La Costa Resort and Spa Master Plan Drainage Study dated November 3, 2003, the total
basin area contributing runoff, to be rated to the proposed CDS Unit (node 544) is approximately twenty-three acres. The storm runoff required to be treated by this unit, per. the City's Storm Water Standards Manual, is calculated as follows:
Q=CIA, where C=0.85, 1=0.2 in/hr, A=23 acres
Q=(0.85) (0.2) (23) = 3.9 1, or approximately 4 c'fs
The CDS Unit, Model No. PMSU40 30 is designed for a maximum flow of 4.5 cfs and is
proposed to be used for this project.
S '
NOTE:
THE INTERNAL COMPONENTS ARE SHOWN
. IN THE RIGHT-HAND CONFIGU RATION -THESE COMPONENTS MAY BE FURNISHED IN THE
MIRROR IMAGE TO THAT SHOWN (LEFT-HAND CONFIGURATION).
PROJECT/ DEVELOPMENT
NAME
CITY -& STATE
DATE
3/24/00
DRAWN
APPROV,
SCALE
1 "=3k
SHEET
1
-
PLAN VIEW
CDS MODEL PMSU40_30.,
4.5 CFS TREATMENT CAP
-*- ELEVATION VIEW
SEE SHEET 2 F
Q STORM
PIPE ,-XX'ø OUTLET PIPE
OPTIONAL 30'0 NH FRAME
I " . •• AND COVER (TYPICAL) ML BAFFLE
LLLL r . . ALTERNATIVE ACCESS
I
LL LLLLLLLL LLLLLLLL'kLLLL;~j AVAILABLE
HATCH SYSTEMS .READILY
LLL
I;
LLL LL 1300 1300 00000103000000
0000 0000000000
coo ...............
0.00.0 01313 13 a
E,
I FIBERGLASS \96 ID CONC
INLET T I
a
NH RISER
I NV CONCRETE
XXØ INLET PIPE
L_ ELEVATION VIEW
SEE SHEET 2
I•.' diS
I
TV DS (C
-
TECHNOLOGIES -
ATENTED
ELEVATION VIEW
CDS MODEL PMSU40_30,
4.5 CFS TREATMENT CAP.
XX'Ø MH COVER & FRAME SEPARATION ALTERNATIVE ACCESS
. SECTION HATCHES AVAILABLE\
Q RISER
GROUT OR USE GRADE •\ SECTIONS
RINGS AS NECESSARY'\
\ FINISHED GRADE
12'' TYP.4
4 .
OUTLET
PIPE
OIL BAFFLE
:.ft II
INLET
PIPE
LV
. PIPE INVERT
EL=XX.XX'
4 S
4. 425"
' 24 SCREEN •
.
.
A.
_______ • •
I ••. 121)P
L~4
280
SUMP
OPENING 3
(TYPICAL)SUMP
I 4
SUMP BOTTOM ___________________ • EL=XX,XX'
DATE
• SCALE
ap PROJECT/ DEVELOPMENT 3/24/00
_
TM
• NAME IDRAWN
• SHEET
.. CITY & STATE
A PPROV
•. .2
TECHNOLOGIES
• PATENTED
.
.
. .
SECTION VIEW
CBS MODEL PMSTJ40_30,
4.5 CFS TREATMENT CAP.
XXø OtJflET PIPE- STORM
\ PIPE I ROTO-HAMMER OR SAW
CUT OPENINGS FOR
PIPE INLET AND OUTLET 1 .
AS NECESSARY
OIL BAFFLE
LL LLLLL
/-LLLLLLLL LL
LLLLLLLLLL
LLL
Ii..'
I ROTATE SEPARATION
. - I SLAB TOOBTAIN
INDICATED OFFSET •. .. .... : . DISTANCES .. :..
.•
FLANGES ON INLET SIDES & BOTTOM 4
ATTACHED TO RISER WM.L USING 6
I ANCHOR .SQITS MINIMUM-(SUPPLIED / 1
I BY COS TECHNOLOGIES)
I
S
.
CENTER OF 960
MH RISER SECTIONS
CENTER OF SCREEN.
280 SUMP OPENING
480 SEPARATION SCREEN.
SEE NOTE NO. 2
ATTACH SCREEN
TO SLAB USING 4
ANCHOR BOLTS,
SUPPLIED BY COS.
ACCESS RISER,
8-O I.D.
XXø INLET PIPE
NOTES:
. I 1. THE INTERNAL COMPONENTS ARE SHOWN IN THE RIGHT-HAND CONFIGURATION -THESE COMPONENTS MAY BE FURNISHED
I
N
T
H
E
MIRROR IMAGE TO THAT SHOWN (LEFT-HAND CONFIGURATI
O
N
)
.
Ii 2. FOR PROPER INSTALLATION, GREEN FLANGE ON
S
C
R
E
E
N
F
A
C
E
S
. UP.
DATE SCALE ... . PROJECT/ DEVELOPMENT 3/24/00 I NAME DRAWN . SHEET
I . . •
CITY & STATE . • •.5. 3.
TECHNOLOGIES
S APPROV PATENTED..
•5. .. • . . 5. 5 • . . •
. .5 5
.
.
•
Tech n o logi s In c®
Phone (3211) 799-0001
Fax (321) 799-1245
-'Grate _._•,c er -- 'IX IX - -
Curb et Basked
k =B offm.
Baffle gay.
1-Blo'CLEANENVIRONMENTAL SERVICES
P.O. Box 869
- - I - £ I iS
Ph: 433'7640
a I I I
I - •I• - - .
I. -- - I - - - 0
I.•:•
BXO ClAN STORAMWATER SYSTEMS
P0 Box 869, Oceanside, CA 92049- I / Pt)Ofle (760) 433-7640 Fax (760) 433-3176
I
-
I ••
an Diego regional standard Curb Intft- Type
1 Manhole
• I Cps
p_L'.•••
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• 1.__=J=
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Catches
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overflow from both-
sides and catcher -
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ithout
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. I Shelf Water Cleaning System Figure22
F3txe I
.
I M&Ede l4
ri
NOTES'
i 1. I S1Bt a*tit j ot Ic Z ShW -.
.. gradeg ,
-• . J . 3. axg
nai / 1?
4 F±kI1 RWELS .4 L_nartan
L 4 .: .' & FOrsdon1e
. 9XAVRk1Mpff3t aAcET
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ge sob twbb8SkBt. qawn rnExiuIedfm tmrtne
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cctioa
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amm and coe
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fo CLkJ Ci1 frJeT F!,kSr
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3. 5 cm c Ft- otV f Y) t~ ts iaS scr t
c~o Yb
I
-v -~ jqJ CAT r -rA.LrL,69 we:ltz IF
IVEIRS
6-23 change of head, whether increasing or decreas
i
n
g
,
a
n
d
w
i
t
h
other conditions.
Among weirs of irregular section there is a lar
g
e
c
l
a
s
s
f
o
r
which, from the nature of their section, the nappe
c
a
n
a
s
s
u
m
e
only one form unless drowned. Such weirs, it
i
s suggested, may, if properly calibrated, equal or exceed the
u
s
e
f
u
l
n
e
s
s
o
f
the thin-edged weir for purposes of stream gaging, beause of their stability of section and because the, thin-
e
d
g
e
d
w
e
i
r
i
s
not free from modification of nappe form for low heads. Broad-crested Weirs. A weir approximately rec
t
a
n
g
u
l
a
r
i
n
cross section is termed a broad-crested weir. Unle
s
s
o
t
h
e
r
w
i
s
e
noed,it will be assumed to have vertical faces, a
p
l
a
n
e
l
e
v
e
l
Fro. 5-6. Broad-crested weir.
crest, and sharp right-angled corners. Figure 54re
p
r
e
s
e
n
t
s
a
broad-crested weir of breadth b. The head H should be measured at least 2.511 upstream from the we
i
r
.
B
e
c
a
u
s
e
o
f
the sharp upstream edge, contraction of the napp
e
o
c
c
u
r
s
.
Surface contraction begins at, a point slightly upstre
a
m
f
r
o
m
the weir.
The discharge over broad-crested weirs is usuall
y
e
x
p
r
e
s
s
e
d
hy the equation
Q = CLIfl
' (5-10) Experiments on broad-crested weirs have been performed by Blackwell, Basin, Woodburn, the U.S. Deep Wa
t
e
r
w
a
y
s
B
o
a
r
d
,
and the f.r.S...Geological $urvey. These experi
m
e
n
t
s
c
o
v
e
r
'
a
wide range of conditiotis a to head, breadth, and h
e
i
g
h
t
o
f
w
e
i
r
.
Considerable, discrepancy exists in the results
o
f
t
h
e
d
i
f
f
e
r
e
n
t
experimenters, especially, for pads below 0.5 ft. F
o
r
h
e
a
d
s
from 0.5 to about 1.5 ft the coefficient becomes more
u
n
i
f
o
r
m
,
and fGr'heads from 1.5 Itt0 that at which the nappe
b
e
c
o
m
e
s
,
detached from the crest, the coefficient asgven by
-the different experiments is nearly constant and equals approximately 2.63.
5-22 HAND3.300K OF
crest is likely to become dulled or ruted, or it ma
y
b
e
d
a
m
a
g
e
d
by floating ice and debris. Under such conditions i
t
m
a
y
b
e
advisable to use a weir with a thicker crest. I
t
i
s
o
f
t
e
n
c
o
n
-
venient to use anexisting weir or overflow dam
f
o
r
m
e
a
s
u
r
i
n
g
discharges. Weirs of various dimensions and s
h
a
p
e
s
a
r
e
u
s
e
d
in hydri.ilic structures. When designing such st
r
u
c
t
u
r
e
s
..,it is important to be able to estimate approximatel
y
t
h
e
d
i
s
c
h
a
r
g
e
s
over these weirs (p.. 2-15).
The amount of water which will pass over a weir, n
o
t
s
h
a
r
p
-
crested, depends to a large extent upon its sectio
n
a
l
f
r
m
a
n
d
the shape of its crest, and it, is necessary to resort t
o
e
x
p
e
r
i
m
e
n
t
to determine the discharge'over any particular s
h
a
p
e
.
I
n
a
s
-
much as the number of shapes of weirs is unlimite
d
,
i
t
i
s
n
o
t
to be expected that experimental data are or eve
r
w
i
l
l
b
e
available for them all. There are available, ho
w
e
v
e
r
,
t
h
e
results of several series of experiments on weirs o
f
d
i
f
f
e
r
e
n
t
cross sections which furnish much valuable i
n
f
o
r
m
a
t
i
o
n
f
o
r
determining discharges over weirs of the same or simi
l
a
r
s
h
a
p
e
s
.
The available experiments are not extensive enou
g
h
f
o
r
.
a
comprehensive study of the effect of velocity of a
p
p
r
o
a
c
h
o
n
weirs not sharp-crested. The coefficients given in th
i
s
c
h
a
p
t
e
r
probably apply more accurately where the velocity
o
f
a
p
p
r
o
a
c
h
is not high. From a consideration of sharp-creste
d
w
e
i
r
s
i
t
appears that discharges, for high velocities of appr
o
a
c
h
,
w
i
l
l
be somewhat greater than is given by formula. (5-
1
0
)
.
Since experimental conditions will seldom be
d
u
p
l
i
c
a
t
e
d
i
n
practice, it is probable that errors may result from
t
h
e
g
e
n
e
r
a
l
use of the coefficients given in this chapter. Extreme accuracy,
however, is not, always necessary in design, wh
e
r
e
u
n
c
e
r
t
a
i
n
t
y
as to the exact quantity of 'water to be provider fo
r
m
a
y
e
x
i
s
t
.
The problem of establishing a fixed relation b
e
t
w
e
e
n
b
e
a
d
and discharge, for weirs not sharp-crested, is co
m
p
l
i
c
a
t
e
d
by the fact that the nappe may assume a variet
y
o
f
f
o
r
m
s
i
n
passing over the weir. Ti'or each modification of nappe form, there is a corresponding change in the relation bet
w
e
e
n
h
e
a
d
and discharge. The effect of this condition.is more noticeable for low heads.-
The nappe may undergo -several of these: modifications in succession as the head is varied. The successi
v
e
f
o
r
m
s
t
h
a
t
appear with an increasing stage may diffe* fr
o
m
t
h
o
s
e
p
e
r
-
taining to similar stages with a. decreasing hed. T
h
e
h
e
a
d
a
t
.
which the changes of nappe form occur varies with
t
h
e
r
a
t
e
o
f
5-40 HANDBOOK OF HYDRAULICS
Table 5-3. Values of C in the Formula Q = C.LHIi for Broad- crested Weirs
WEIRS 5-41 Table 5-5. Values of C in the Formula Q CLIflS for Broad- crested Weirs'with Crests Inclined Slightly Dow
n
w
a
r
d
(d)
Energy head H. Crest
0.5 0,6 0.7
EIi 0.8 0.9 1.0 1.2 1.4 1.5
Level......... ..........
2 522 822 83 852 85285
.2.782.792.80 S1ope0.004 ........... 2.'P5 2.94 2.93 2.92 2.01 2.9 0 87287
Slope 0.026 ........... .5.073.063,05304
3
ô
3
3
0
2
3
0
0
2
9
9
S..
(i')
Slope of Length Head in feet, H creet
ir
weir Ufee 0.1 t 0.2 0.3 0,4 0.50.6 0.7 •• -......-.. -.....--.-
..• 12 to _3_0 2.58 2.87 2.57 2.60 2.84 2.81 2.70 .
'I
...••-
Table 5-4. Values of C i the Formula Q C1H.for Models of Broad-crested Weirs with Rounded tJpstrea
n
C
o
r
n
e
r
Bead in feet
-10
, H
,tna of experimenter
o.4\o.6\o.si.o\1.5\2.12.5\3.14.0\5.0
51 X
0.33 2.62 2.46 2.93 2.91 2.88 2.01 2.04 llnziii .......... .0.33 8.58 2.48 2.70 2.82 3.97 2.80 2.02
Weterwayø... 0.33 2.52 4.57 .... 2.71 3.80 2.83 2.02 2.00 3.08 0.37 3.34 3.50
Waterways ... 0.33 5.10 4.56...........2.83 2.81 2.83 2.82 2.80 2.82 2.82
2
.
8
1
Table 5-6. Values of C in the Formula Q CLHIS for Weirs of Triangular Cross Section with Vertical Upstre
a
m
F
a
c
e
and Sloping Downstream Face
Slope of Height
Heed In feet, H down- of stream In feet. face F. 0.2 0.3 04 0.5 0.6 0.7 0.8 0.9 1.0 2
.
2
1
,
5
Hot, Vert. .
S 1 to 1 2.46 3.88 3.85 3.85 3.85 3.85 3.85 3.85 3,85 3.85 3.85 3.
8
5
2to1 2.46 L483,453.493,493 503 503
5
0
3
.50 3 503 51351
2tal 1.64 .53.473.4735l3 543 573583
5
8
3
5
8
3
5
0
3
5
7
3to1 1.64 ;...2,903,113,223 26333327
3
4
0
3
4
0
3
4
3
3
4
1
.
Slot 2.46 .... 3.08E063,053,053.073.09312333313313 .
1010 1 2,45 .......2.82 '1.83 2.84 2.86 2.89 2.90 2.91
2
,
9
1
2
.
9
2
2
.
9
3
_faL~W104 q"
!I .5
•••-•
..•.S •,1•1r .
-- ,-• i• - -
- a_ - - -
'i 1 11111(21 \ ( 2 I
'1
I., td fl?..Nr,+1