HomeMy WebLinkAboutCT 12-05; La Costa Residential; Tentative Map (CT) (5)I
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PRELIMINARY
STORM WATER MANAGEMENT PLAN
FOR
LA COSTA RESIDENTIAL
(CT 12-05, PUD 12-07)
January 30, 2013
Civil Engineering o Hydrology o Hydraulics o Sedimentation
P.O. Box 9496
Rancho Santa Fe, CA 92067
(858) 692-0760
RECEIVED
FEB 0 6 2013
CITY OF CARLSBAD
PLANNING DIVISION
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1.0
1.1
1.2
1.3
1.4
2.0
2.1
2.1.1
2.1.2
3.0
3.1
3.2
4.0
4.1
4.2
4.3
4.4
4.5
-TABLE OF CONTENTS-
Introduction ....................................................................................................................... !
Vicinity Map ..................................................................................................................... !
Project Description ............................................................................................................ 2
Site Map ........................................................................................................................... .3
Constraints and Opportunities .......................................................................................... .3
Water Quality Environment .............................................................................................. 3
Beneficial Uses ................................................................................................................ .3
Inland Surface Waters ....................................................................................................... 4
Groundwater ..................................................................................................................... 4
Pollutants and Conditions of Concern ............................................................................. .4
Pollutants from Project Area ............................................................................................ .4
Pollutants of Concern in Receiving Waters ...................................................................... 5
Permanent Storm Water Best Management Practices ...................................................... 6
Standard Site Design BMPs .............................................................................................. 6
Source Control BMPs ....................................................................................................... ?
Low Irnpact Development Site Design BMPs .................................................................. 9
Treatment Control BMPs .................................................................................................. 9
Hydrornodification .......................................................................................................... 1 0
5.0 Storm Water BMP Maintenance ..................................................................................... !!
6.0 Summary /Conclusions .................................................................................................... 12
7.0 Certification .................................................................................................................... 14
Storm Water Standards Questionnaire, E-34
Site Map
APPENDIX
A. Low Impact Development and Hydromodification Analyses
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1.0 INTRODUCTION
This preliminary Storm Water Management Plan (SWMP) addresses water quality
requirements associated with the La Costa Town Square project, which is a proposed
residential subdivision in the city of Carlsbad. This SWMP accompanies the Preliminary
Review plans by the project's civil engineer, Latitude 33, and follows the criteria outlined in
the City of Carlsbad's January 14, 2011, Standard Urban Storm Water Management Plan
(SUSMP).
According to the City's Storm Water Standards Questionnaire E-34 (attached following this
report text), the development is in the following three priority project categories: Housing
subdivisions of 10 or more dwelling units; Streets, roads, highways, and freeways; and More
than !-acre of disturbance. The SUSMP outlines the SWMP objectives, which are to identity
site opportunities and constraints, identity pollutants and conditions of concern, follow low
impact development design objectives, describe best management practices (BMPs), and
outline maintenance requirements. BMPs will be utilized to the maximum extent practicable
to provide a long-term solution for addressing runoff water quality. BMPs were selected by
Latitude 33 to meet the objectives.
l.l Vicinity Map
PAQFIC
OCEAN
VICINITY MAP
PROJECT SITE
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1.2 Project Description
The La Costa Town Square project is a proposed residential subdivision that will consist of
32 detached single-family residences along with associated driveways, sidewalks,
landscaping, and drainage facilities (see the Site Map following this report text). The
development will be constructed within an undeveloped 9. 9 acre parcel along the north side
of Rancho Santa Fe Road and west ofPaseo Lupino.
Under pre-project conditions, the site is mostly pervious and covered with vegetation or bare
soil. A nearly 5 acre development pad has been mass-graded within the site. As part of the
mass-grading, manufactured 2:1 slopes exist around the perimeter of the pad. The triangular-
shaped pad is higher than the adjacent ground to the northwest and south, and both higher
and lower than the adjacent ground to the east. The pad is primarily gently sloping towards
an existing desiltation basin at its southwest comer. An existing storm drain pipe conveys
storm runoff out of the desiltation basin and away from the site. The off-site storm drain
system continues in a northwesterly direction for over half a mile and ultimately outlets into
a natural canyon that flows into San Marcos Creek just east of the east end of the La Costa
Resort & Spa's South (golf) Course. San Marcos Creek continues westerly through the golf
course where it discharges into Batiquitos Lagoon.
A small area of pre-project runoff from the development pad will flow easterly down the site
entrance and onto Paseo Lupino. An existing curb inlet along the west side of Paseo Lupino
about 70 feet south of the site entrance near Rancho Santa Fe Road captures this runoff.
Under post-project conditions, most of the on-site runoff will continue to be conveyed in a
southwesterly direction across the pad and ultimately enter the existing storm drain system
near the southwest comer of the project area. A small area near the northerly comer of the
project will flow into an existing concrete drainage ditch that conveys runoff in a
southwesterly direction along the northerly toe of slope of the pad. The ditch ultimately
directs its runoff into the existing storm drain system near the southwest comer of the project
area. The on-site proposed condition runoff from these areas will enter one of five
bioretention basins for treatment and hydromodification control prior to leaving the site. In
addition, a proposed detention basin will be constructed just southwest of the pad and
mitigate for 1 00-year flow increases due to the project. Some of the bioretention basins will
also be used for detention during final engineering.
A small portion of Paseo Lupino near the site entrance will contain pervious pavers. The
pervious pavers will act as self-treating areas that require no additional treatment or flow
control. Only direct precipitation on the pervious pavers will infiltrate into the pavers. Lot I
and a portion of Lot 2 are adjacent to and flows towards the pavers. The water quality runoff
from these lots will be conveyed in the adjacent curb and gutter then collected by a trench
drain at the site entrance. The trench drain will convey the runoff north into BMP 3. The
curb, gutter, and trench drain will prevent the water quality runoff from Lots I and 2 from
entering the pervious pavers.
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1.3 Site Map
A Site Map is included following this report text.
1.4 Constraints and Opportunities
As shown on the site map, the development will occur within a previously mass-graded pad
intended for development. The pre-project drainage patterns are being maintained by the
project.
The development will consist of detached single-family residences surrounded by gently
sloping landscape areas and some shared drive aisles. The landscape areas provide
opportunities to treat runoff through contact and bio-filtration by vegetation. For several of
the residences, shared drive aisles will be used to minimize impervious surfaces. Bioretention
basins are proposed at five areas within the development area. The bioretention basins will be
used to meet both treatment and hydromodification requirements. Latitude 33's plans contain
more details on the bioretention basins.
2.0 WATER QUALITY ENVIRONMENT
2.1 Beneficial Uses
The beneficial uses for the hydrologic unit (see Section 3.1) are included in Tables 1 and 2.
These tables were obtained from the Water Quality Control Plan for the San Diego Basin (9)
compiled on August 28,2012. The following contains definitions of the beneficial uses in the
tables:
MUN -Municipal and Domestic Supply: Includes uses of water for community,
military, or individual water supply systems including, but not limited to, drinking
water supply.
AGR -Agricultural Supply (AGR): Includes uses of water for farming,
horticulture, or ranching including, but not limited to, irrigation, stock watering, or
support of vegetation for range grazing.
RECl -Contact Recreation: Includes uses of water for recreational activities
involving body contact with water, where ingestion of water is reasonably possible.
These uses include, but are not limited to, swimming, wading, water-skiing, skin and
SCUBA diving, surfing, white water activities, fishing, or use of natural hot springs.
REC2 -Non-Contact Recreation: Includes the uses of water for recreational
involving proximity to water, but not normally involving body contact with water,
where ingestion of water is reasonably possible. These uses include, but are not
limited to, picnicking, sunbathing, hiking, camping, boating, tide pool and marine life
study, hunting, sightseeing, or aesthetic enjoyment in conjunction with the above
activities.
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2.1.1
WARM -Warm Freshwater Habitat: Includes uses of water that support warm
water ecosystems including, but not limited to, preservation or enhancement of
aquatic habitats, vegetation, fish or wildlife, including invertebrates.
WILD -Wildlife Habitat: Includes uses of water that support terrestrial ecosystems
including, but not limited to, preservation and enhancement of terrestrial habitats,
vegetation, wildlife, (e.g., mammals, birds, reptiles, amphibians, invertebrates), or
wildlife water and food sources.
Inland Surface Waters I Inland surface waters for the San Marcos Hydrologic Area (see Section 3.1) have the
beneficial uses shown in Table I:
I Table 1. Beneficial Uses for Inland Surface Waters
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Hydrologic
Unit -"' ~ Code § Eh u ~ .c ~ u u 0 "" £ ~ 0 "' "' :::; ..= ~ iii ~ < 0 ""' 0.. ~ ~
904.51 + • • • •
+Exempted by the Regional Board from the municipal used designation.
• Existing Beneficial Use
2.1.2 Groundwater
:!l :!l "' c
~ ~ 0 ~ " 0. u ~ Cll
•
Groundwater beneficial uses for the El Saito Hydrologic Subarea are shown in Table 2:
Table 2. Beneficial Uses for Groundwater
Hydrologic
Unit
Code c Eh u .c ~ ~ "" e ~ < ..= ~ 0 0.. ""' 904.51 • • •
• Extstmg Benefic tal Use
3.0 POLLUTANTS AND CONDITIONS OF CONCERN
3.1 Pollutants from Project Area
The project is located within the Batiquitos Hydrologic Subarea (904.51) of the San Marcos
Hydrologic Area (904.50), which is within the Carlsbad Hydrologic Unit (904.00). The total
drainage area of the hydrologic unit is approximately 210 square miles. Runoff from portions
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of the hydrologic subarea ultimately drains to Batiquitos Lagoon, which is west ofthe project
site. All of the project runoff will ultimately enter Batiquitos Lagoon. The project site
represents less than one percent of the overall watershed.
The following table lists pollutants of concern that are anticipated or can potentially exist at
proposed priority development project sites. The pollutants are from the city of Carlsbad's
SUSMP. The project falls within the detached residential development and streets, highways
& freeways priority project categories (highlighted yellow in the table). All of the listed
pollutants are either anticipated or can potentially exist at the developed site.
Table 3. Priority Project Pollutants
Priority Trash Oxygen Heavy Organic Project Sediments Nutrients & Demanding Metals Compounds Catef;!ories
Detached
Residential
Development
Attached
Residential
Development
Commercial
Development
>one acre
Heavy
Industry
Automotive
Repair Shops
Restaurants
Hillside
Development
>5,000 ft2
Parking Lots
Retail
Gasoline
Outlets
Streets,
Highways&
Freeways .. X-AntiCipated
P = Potential
X X
X X
p(i) p(l) X p(2)
X X X
X x<4J(SJ
X X
pOl pOl X
X X
X p(i) X x<4J
(I) A potential pollutant iflandscaping exists on-site
Debris
X
X
X
X
X
X
X
X
X
X
(2) A potential pollutant if the project includes uncovered parking areas
(3) A potential pollutant if land use involves food or animal waste products
(4) Including petroleum hydrocarbons
(5) Including solvents
3.2 Pollutants of Concern in Receiving Waters
Substances
X
p(l)
p(S)
X
X
X
p(l)
X
p(5)
Oil Bacteria
& & Pesticides
Grease Viruses
X X X
p(2) p X
X p(3) p(S)
X
X
X X p(l)
X X
X p(l)
X
X X pOl
The receiving waters for the site include Encinitas Creek (small amount of on-site runoff
tributary to curb inlet in Paseo Lucindo ), San Marcos Creek (on-site runoff from remainder
of site), and Batiquitos Lagoon (entire site). According to the 2008 303( d) list approved by
the State Water Resources Control Board (and by the US EPA in November 2010), Encinitas
Creek is 303(d) listed for phosphorus, selenium, and toxicity. San Marcos Creek is 303(d)
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listed for DOE, phosphorus, sediment toxicity, and selenium. Batiquitos Lagoon, is not
303(d) listed. None of the three water bodies is subject to total maximum daily loads
(TMDLs). Based on this information, the project generates pollutants of concern in the
receiving waters for sediment and nutrients (phosphorus).
4.0 PERMANENT STORM WATER BEST MANAGEMENT PRACTICES
To address water quality for the project, best management practices (BMPs) will be
implemented. The following discusses the Standard Site Design, Source Control, and Low
Impact Development design BMPs for the project.
4.1 Standard Site Design BMPs
The City of Carlsbad's standard objectives are required for all projects. The project will
accomplish these goals through the following standard site design BMPs, which are from the
Carlsbad SUSMP:
Standard Stormwater Requirements
Minimize Impervious Surfaces. The project will include pervious surfaces through
landscaping within the development area. The project will not disturb the majority of the
natural areas beyond the previously mass-graded development pad.
Disconnect Discharges. Roof drains will discharge to adjacent landscape areas, where
feasible. The proposed sidewalks along the private cul-de-sac street within the site are being
designed with a landscaped parkway between the sidewalks and curbs to allow runoff to
drain over adjacent landscape areas.
Conserve Natural Areas. The majority of the areas beyond the perimeter of the mass-graded
pad will not be disturbed by the project.
Stenciling Inlets and Signage. The curb cuts and inlets within the project will be stenciled
with prohibitive language such as "No Dumping-I live downstream" or approved similar.
Landscape Design. A landscape plan will be prepared that uses drought-tolerant species in
accordance with the City's landscape manual. Native trees and shrubs will be preserved
beyond the majority of the mass-graded pad in order to maximize canopy interception and
promote water conservation. The project will only use water as needed to support the
landscaping.
Water Efficient Irrigation. The irrigation systems will be designed to each landscaped areas
water requirements to avoid over irrigation. Rain shutoff devices will be used to prevent
irrigation after rain events.
Protect Slopes And Channels. The grading design does not include large slopes or any
channels. The design will prevent runoff from flowing uncontrolled over the tops of
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manufactured slopes. The proposed slopes will be landscaped. Riprap energy dissipaters will
be used at storm drain outfalls.
Vegetate slopes with native or drought tolerant vegetation. Native and drought tolerant
vegetation will be used to the extent feasible.
Trash Receptacles. Each residence will have personal, covered trash receptacles.
Material Storage Areas. The project does not propose outdoor material storage areas. Any
required material storage shall be kept under cover.
4.2 Source Control BMPs
Source control BMPs will consist of measures to prevent polluted runoff. The following
addresses the source control BMPs from Appendix 1 of the Carlsbad SUSMP:
Table 4. Pollutant Sources and Source Control Checklist
Potential Source Permanent Source Operational Source
of Runoff Pollutants Control BMPs Control BMPs
On-site storm drain Mark all inlets with "No • Maintain and periodically
inlets Dumping - I live downstream" repaint inlet markings
• Provide stormwater pollution
information to owners, lessees,
and operators (Fact sheet SC-
44 from the CASQA
Stormwater Quality Handbook
at www.cabmQhandbooks.com)
• Owner/lessee agreements shall
state "Tenant shall not allow
anyone to discharge anything to
storm drains or to store or
deposit materials so as to create
a potential discharge to storm
drains.
Need for future Buildings shall be designed to Integrated Pest Management (e.g.,
indoor & structural avoid openings that would the EPA's Citizen's Guide to Pest
pest contro I encourage entry of pests. Control and Pesticide Safety)
information shall be provided to
owners, lessees, and operators.
Landscape/Outdoor Final landscape plans will Maintain landscaping using
Pesticide Use accomplish all of the minimum or no pesticides.
following. See applicable operational BMPs
• Preserve existing native trees, in Fact Sheet SC-41, "Building and
Grounds Maintenance," and TC-shrubs, and ground cover to 30, "Vegetated Swale," in the
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Vehicle and
equipment cleaning
Vehicle/Equipment
Repair and
Maintenance
Roofing, gutters, and
trim
Plazas, sidewalks,
and parking lots.
the maximum extent possible. CASQA Stormwater Quality
Handbooks at
• Design landscaping to www.cabmQhandbooks.com
minimize irrigation and Integrated Pest Management (e.g., runoff, to promote surface the EPA's Citizen's Guide to Pest infiltration where Control and Pesticide Safety)
appropriate, and to minimize information shall be provided to
the use of fertilizers and owners, lessees, and operators.
pesticides that can contribute
to stormwater pollution.
• Where landscaped areas can
retain or detain stormwater,
specifY plants that are
tolerant of saturated soil
conditions.
• Consider using pest-resistant
plants, especially adjacent to
hardscape.
• To ensure successful
establishment, select plants
appropriate to site soils,
slopes, climate, sun, wind,
rain, land use, air movement,
ecological consistency, and
plant interactions
The CC&Rs will define car
washing requirements and
restrictions at the site. The
HOA will be responsible for
enforcing the requirements and
restrictions.
The CC&Rs will prohibit
repair and maintenance
activities in areas exposed to
precipitation and storm flows.
The HOA will be responsible
for enforcing this requirement.
The architectural design will
avoid roofing, gutters, and trim
made of copper or other
unprotected metals that may
leach into runoff.
Plazas, sidewalks, and parking lots
shall be swept regularly to prevent
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4.3 Low Impact Development Site Design BMPs
the accumulation of litter and
debris. Debris from pressure
washing shall be collected to
prevent entry into the storm drain
system. Wash water containing
any cleaning agent or degreaser
shall be collected and discharged
to the sanitary sewer and not
discharged to a storm drain.
Low Impact Development (LID) BMPs must be incorporated into the site design to meet the
City of Carlsbad's January 14, 2011 SUSMP requirements. The integrated LID outlines five
strategies:
1. Optimize the site layout by preserving natural drainage features and designing
buildings and circulation to minimize the amount of roofs and paving.
2. Use pervious surfaces such as turf, gravel, or pervious pavement--or use surfaces that
retain rainfall. All drainage from these surfaces is considered to be "self-retained".
3. Disperse runoff from impervious surfaces on to adjacent pervious surfaces (e.g.,
direct a roof downspout to disperse runoff onto a lawn).
4. Drain impervious surfaces to engineered Integrated Management Practices (IMPs),
such as bioretention facilities. IMPs infiltrate runoff to groundwater and/or percolate
runoff through engineered soil and allow it to drain away slowly.
The project design is in compliance with these strategies. The site layout has been designed
to preserve natural areas beyond the mass-graded pad. Shared drive aisles will provide access
to many of the units and the on-site streets are being designed with minimal widths.
Runoff from the roofs will flow towards pervious landscape areas, where possible, and
ultimately enter a bioretention basin. Bioretention basins will also be used to treat the
additional on-site runoff and to meet hydromodification requirements (discussed in next
section). Bioretention basins provide high to medium removal effectiveness for the pollutants
generated by the project, which are listed in Table 3. Preliminary sizing is included in
Appendix A of this report. The final bioretention basins will be sized using County of San
Diego's BMP Sizing Calculator.
4.4 Treatment Control BMPs
Treatment control BMPs were selected to treat the project pollutants of concern identified in
Table 3. Bioretention basins will be used because they have a medium to high pollutant
removal efficiency for the project's pollutants of concern. For treatment control only, a
bioretention basin's surface area must be at least 4 percent of the total area determined from
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the Drainage Management Areas. For the project, the bioretention basins will also provide
hydromodification flow control. The sizing is discussed in the next section.
4.5 Hydromodification
The January 14, 2011 SUSMP requires hydromodification (flow control) for priority
development projects to ensure that post-development peak flows do not exceed pre-
development peak flows. La Costa Town Square is a priority development project and must
meet the hydromodification requirement. This can be accomplished by sizing bioretention
facilities using the criteria in the County of San Diego's SUSMP.
The proposed project will have five bioretention basins spread throughout the site (see the
Drainage Management Areas exhibit in Appendix A). Since this is a Preliminary SWMP,
conceptual sizing for the bioretention basins was performed using the sizing factors from
Table 7-4 of the County of San Diego's HMP (see Appendix A). The required bioretention
basin surface area and storage volumes obtained from Table 7-4 will be similar to the surface
area and storage volumes obtained from the County's BMP Sizing Calculator. The orifice
sizing is not provided by Table 4-8, but this is not needed for conceptual analyses. The BMP
Sizing Calculator (or approved equivalent) will need to be used during final engineering.
Data entry for hydromodification analyses using Table 7-4 is based on the lower flow
threshold, soil group, slope, and rain gage. A lower flow threshold of 0.1 Q2 is used because a
downstream channel screening assessment has not been performed. It is possible that if such
analysis is performed in the future a higher low flow threshold could be used. The site is
within the Oceanside rainfall basin and contains soil group D. The average slope along the
mass-graded pad is in the range of I to 2 percent, which is within the "flat" category. Based
on this data, Table 7-4 indicates that the sizing factors for A (surface area), V1 (surface
volume), and V2 (subsurface volume) are 0.160, 0.1333, and 0.0960, respectively.
The preliminary bioretention sizing analyses are included in Appendix A. The Drainage
Management Areas (DMA) exhibit in Appendix A delineates the drainage areas tributary to
each of the five bioretention basins. Each drainage area is subdivided into its roofs,
driveways, streets, sidewalks, and landscaping. The driveways are based on the assumption
of 400 square feet per lot. A spreadsheet is included in Appendix A summarizing the DMAs
tributary to each bio-retention basin as well as the calculated surface area, surface volume,
and subsurface volume. The results are included in Table 5.
Table 5. Summary of Bioretention Sizing
Bioretention Surface Surface Subsurface
Basin Area, sf Volume, cf Volume, cf
1 2,969 2,473 1,781
2 1,932 1,610 1,159
3 3,212 2,676 1,927
4 1,769 1,474 1,062
5 9,940 8,281 5,964
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Note: Bioretention basins will contain an impervious liner, so were
sized based on flow-through planter sizing factors.
Bioretention basins 1, 2, 3, 4, and 5 shown on the Preliminary Review plans generally meet
the surface area requirements from Table 5 or the area based on the 4 percent minimum
criteria. The bioretention sizing shall be refined during final engineering. The bioretention
sizing based on the above described procedure is included in the spreadsheet in Appendix A.
The County of San Diego's Final HMP states that the ponding layer (V 1) and storage layer
(V2) are converted to volumes "so that the project designer can flexibly configure the
ponding layer and storage layer to meet site constraints" (see excerpt in Appendix A). This
can be done, as needed, during final engineering. For instance, the standard County
bioretention basin design shows a 4-foot layer below the surface. This depth can be increased
above 4 feet to meet the volume requirements in instances where the available surface area is
less than the area, A. However, the surface area must be maintained greater than 4 percent of
the adjusted area in order to satisfy treatment control sizing. The City's draw down
requirement at the time of design must also be met. Ultimately, the bioretention basins shall
meet both treatment control and hydromodification requirements.
The southeast portion of the proposed project will flow towards pervious pavement within
the site entrance from Paseo Lucindo. The DMA exhibit also includes this drainage area. The
pervious pavement is intended to be a self-treating area that requires no additional treatment
or flow control. Only direct precipitation will enter the pervious pavement.
5.0 STORM WATER BMP MAINTENANCE
The developer will be responsible for funding and implementing the operations and
maintenance of the project BMPs. Provisions will be made to transfer operations and
maintenance to the new owner in the event of a change in ownership. The homeowner's
association will ultimately be responsible for ongoing operations and maintenance. The
following describes the specific BMP maintenance.
Bioretention basins
The drainage outlet from the basins shall be inspected monthly and after large storm events.
Debris, sediment, and other obstructions shall be removed immediately from the outlet. The
habitat shall also be inspected annually and replanted as needed to maintain an adequate
cover.
Pervious Pavement
After installation, inspect pavement once a month for 4 to 6 months. After this period
inspection can occur annually, particularly after there has been heavy rain or storms, for this
is the time when the drainage voids can become clogged with organic debris. Sweep and/or
vacuum the permeable surface every 3 months. Street sweepers that have a vacuum and
brushes can be used. High pressure hosing shall be performed after sweeping/vacuuming.
Voids should be kept filled with aggregate.
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Landscaping and Vegetated Swales
Maintenance wiil be performed by landscaping personnel. The vegetation wiil be maintained
and inspected on a monthly basis by landscape maintenance staff and will be replaced or
replanted, as necessary, to maintain a dense, healthy cover. The vegetation wiil also be
inspected after major storm events. Maintenance shall include periodic mowing, weed
control, irrigation, reseeding/replanting of bare areas, and clearing of debris. A design grass
height of 6 inches is recommended. Grass clippings shall not be left in grass swales. The
private drainage system will shall be kept clear of debris and inspect prior to and during the
rainy season to ensure it is free-flowing.
Efficient Irrigation
The landscaping personnel shall inspect and maintain the irrigation system on a regular basis.
This will occur during the routine maintenance activities. All valves, heads, shutoff devices,
lines, etc. shall be kept in a properly functioning condition. Any defective parts shall be
replaced immediately. The irrigation system shall be adjusted to prevent excessive runoff
from landscape areas. The irrigation schedule shall be adjusted based on seasonal needs.
Inlet Stenciling
Any stenciling shall be inspected at the beginning and end of each rainy season and repaired
or replaced, as needed.
Hazardous Wastes
Suspected hazardous wastes will be analyzed to determine disposal options. Hazardous
materials are not expected to be generated on-site; however, if discovered, hazardous
materials will be handled and disposed of according to local, state, and federal regulations. A
solid or liquid waste is considered a hazardous waste if it exceeds the criteria listed in the
California Code of Federal Regulations, Title 22, Article 11 (State of California, 1985).
6.0 SUMMARY/CONCLUSIONS
This final SWMP has been prepared in accordance with the City of Carlsbad's January 14,
2011, Standard Urban Storm Water Management Plan, and has evaluated and addressed
potential pollutants associated with the Muroya project and its effects on water quality. This
SWMP has been based on the final engineering plans. A summary of the facts and findings
associated with the project and the measures addressed by this S WMP are as follows:
• The beneficial uses for the receiving waters have been identified. BMPs will be used
to protect the beneficial uses as outlined by the SUSMP.
• The project will not significantly alter drainage patterns and will meet
hydromodification requirements.
• A Storm Water Pollution Prevention Plan for construction activities has been
prepared to address construction-related water quality objectives.
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• Permanent BMPs will be incorporated into the project design in the form of site
design, source control, and LID treatment control.
• The proposed BMPs address mitigation measures to protect water quality and
beneficial uses to the maximum extent practicable.
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7.0 CERTIFICATION
The selection, sizing, and preliminary design of stormwater treatment and other control
measures in this plan meet the requirements of Regional Water Quality Control Board Order
R9-2007-0001 and subsequent amendments.
January 30, 2013
Date
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«~~ ¥ CITY OF
CARLSBAD
STORM WATER
STANDARDS
QUESTIONNAIRE
E-34
Development Services
Land Development Engineering
1635 Faraday Avenue
760-602-2750
www.carlsbadca.gov
To address post-development pollutants that may be generated from development projects, the City requires that new
development and significant redevelopment priority projects incorporate Permanent Storm Water Best Management
Practices (BMP's) into the project design per the City's Standard Urban Stormwater Management Plan (SUSMP). To
view the SUSMP, refer to the Engineering Standards (Volume 4, Chapter 2) at www.carlsbadca.gov/standards.
Initially this questionnaire must be completed by the applicant in advance of submitting for a development application
(subdivision, discretionary permits and/or construction permits). The results of the questionnaire determine the level of
storm water standards that must be applied to a proposed development or redevelopment project. Depending on the
outcome, your project will either be subject to 'Standard Stormwater Requirements' or be subject to additional criteria
called 'Priority Development Project Requirements'. Many aspects of project site design are dependent upon the
storm water standards applied to a project.
Your responses to the questionnaire represent an initial assessment of the proposed project conditions and impacts.
City staff has responsibility for making the final assessment after submission of the development application. If staff
determines that the questionnaire was incorrectly filled out and is subject to more stringent storm water standards than
initially assessed by you, this will result in the return of the development application as incomplete. In this case, please
make the changes to the questionnaire and resubmit to the City.
If you are unsure about the meaning of a question or need help in determining how to respond to one or more of the
questions, please seek assistance from Land Development Engineering staff.
A separate completed and signed questionnaire must be submitted for each new development application submission.
Only one completed and signed questionnaire is required when multiple development applications for the same project
are submitted concurrently. In addition to this questionnaire, you must also complete, sign and submit a Project Threat
Assessment Form with construction permits for the project.
Please start by completing Section 1 and follow the instructions. When completed, sign the form at the end and submit
this with your application to the city.
Examples: single family homes, multi-family homes,
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manufacturing plants, food processing plants, metal
(bus, truck, etc.).
in any one of Standard Industrial Classification (SIC) codes 50
stands selling prepared foods and drinks for immediate consumption (SIC code , where the
land area for development is greater than 5,000 square feet. Restaurants where land development is less than 5,000
square feet shall meet all SUSMP requirements except for structural treatment BMP and numeric sizing criteria
YES
X
E-34 Page 1 of 3 REV 1114111
NO
X
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6.
7.
8.
9.
«~~ ~ CITY OF
CARLSBAD
STORM WATER
STANDARDS
QUESTIONNAIRE
E-34
Development Services
Land Development Engineering
1635 Faraday Avenue
760-602-2750
www.carlsbadca.gov
Hillside development. Any development that creates more than 5,000 square feet of impervious surface and is
located in an area with known erosive soil conditions, where the development will grade on any natural slope that is X twenty-five percent (25%) or oreater.
Environmentallv Sensitive Area fESAJ'. All development located within or directly adjacene to or discharging
directly3 to an ESA (where discharges from the development or redevelopment will enter receiving waters within the X ESA), which either creates 2,500 square feet or more of impervious surface on a proposed project site or increases
the area of imperviousness of a proposed project site 10% or more of its naturally occurring condition.
Parking lot. Area of 5,000 square feet or more, or with 15 or more parking spaces, and potentially exposed to urban X runoff
Streets. roads. highways. and freeways. Any paved surface that is 5,000 square feet or greater used for the X transportation of automobiles, trucks, motorcycles, and other vehicles
10. Retail Gasoline Outlets. Serving more than 100 vehicles per day and greater than 5,000 square feet X
11. Coastal Development Zone. Any project located within 200 feet of the Pacific Ocean and (1) creates more than X 2500 square feet of impervious surface or (2) increases impervious surface on property by more than 10%.
12. More than 1-acre of disturbance. Project results in the disturbance of 1-acre or more of land and is considered a
Pollutant-generating Development Project4. X
1 Enwonmentally SenSitive Areas Include but are not 11m1ted to all Clean Water Act Sect1on 303(d) 1mpa1red water bod1es, areas des1gnated as Areas of Spec1al
Biological Significance by the State Water Resources Control Board (Water Quality Control Plan for the San Diego Basin (1994} and amendments); water bodies
designated with the RARE beneficial use by the State Water Resources Control Board {Water Quality Control Plan for the San Diego Basin (1994) and amendments);
areas designated as preserves or their equivalent under the Multi Species Conservation Program within the Cities and County of San Diego; and any other equivalent
environmentally sensitive areas which have been identified by the Copermittees.
2 "Directly adjacent" means situated within 200 feet of the Environmentally Sensitive Area.
3 "Discharging directly to' means outflow from a drainage conveyance system that is composed entirely of flows from the subject development or redevelopment site. and
not commingled with flow from adjacent lands.
4 Pollutant-generating Development Projects are those projects that generate pollutants at levels greater than background levels. In general, these include all projects
that contribute to an exceedance to an impaired water body or which create new impervious surfaces greater than 5000 square feet and/or introduce new landscaping
areas that require routine use of fertilizers and pesticides. In most cases linear pathway projects that are for infrequent vehicle use, such as emergency or maintenance
access, or for pedestrian or bicycle use, are not considered Pollutant-generating Development Projects if they are built with pervious surfaces or if they sheet flow to
surrounding pervious surfaces.
INSTRUCTIONS:
Section 1 Results:
If you answered YES to ANY of the questions above, your project is subject to Priority Development Project requirements. Skip Section 2 and
please proceed to Section 3. Check the "meets PRIORITY DEVELOPMENT PROJECT requirements" box in Section 3. Additional storm water
requirements will apply per the SUSMP.
If you answered NO to ALL of the questions above, then please proceed to Section 2 and follow the instructions.
E-34 Page 2 of3 REV 1/14/11
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~ .-~ ',,"! ~ -~ CITY 0 F
CARLSBAD
I you
STORM WATER
STANDARDS
QUESTIONNAIRE
E-34
Development Services
Land Development Engineering
1635 Faraday Avenue
760-602-2750
www.carlsbadca.gov
YES NO
PROJECT requirements. Please check nmeets PROJECT requirementsQ box in Section 3 below. Review
SUSMP to find out if SUSMP requirements apply to your project envelope or the entire project site.
If you answered 1'10, then you ARE NOT a significant redevelopment and your project is subject to STANDARD STORMWATER
REQUIREMENTS. Please check the "does not meet PDP requirements" box in Section 3 below.
SECTION3 QUESTIONNAIRE RESULTS
lXI My project meets PRIORITY DEVELOPMENT PROJECT (POP} requirements and must comply with additional stormwater criteria
per the SUSMP and I understand I must prepare a Storm Water Management Plan for submittal at time of application. I understand
flow control (hydromodification) requirements may apply to my project. Refer to SUSMP for details.
0 My project does not meet POP requirements and must only comply with STANDARD STORMWATER REQUIREMENTS per the
SUSMP. As part of these requirements, I will incorporate low impact development stratecies throuahout mv oroiect.
Applicant Information and Signature Box
Address: North of Rancho Santa Assessor's Parcel Number(s): City Concurrence: YES NO
I ., Fe Road, West of Paseo Lupine 223-050-68, 223-060-31
Applicant Name: Applicant Title:
April Tornillo Forward Planner Date:
Date: Project ID·
December 5, 2012
E-34 Page3of3 REV 1/14/11
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LEGEND:
PROPOSED STORM DRAIN
PROPOSED BIORETENTION BASIN
1, = 1 00'
~
0 100
SITE MAP
LA COSTA TOWN SQUARE
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APPENDIX A
LOW IMPACT DEVELOPMENT
AND HYDROMODIFICATION ANALYSES
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SUMMARY
The SUSMP requires that Drainage Management Areas (DMA) be delineated for various surface
types. DMAs were determined for roofs, landscaping, sidewalks, paving, and a concrete drainage
ditch. These are shown on the DMA Exhibit in this appendix. The attached spreadsheet
summarizes the DMAs to each of the bioretention basin areas. The bioretention basins have been
sized in the spreadsheet using factors in Table 7-4 of the County of San Diego's HMP.
Continuous simulation calculations for flow control orifice sizing and drawdown time
calculations shall be provided during final engineering.
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------------------
LEGEND:
BMP DRAINAGE BASIN BOUNDARIES
ROOFS
STREETS
SIDEWALKS
I I LANDSCAPING
-PERVIOUS PAVING (NOT INCLUDED IN BMP 3)
BIORETENTION BASIN
DRIVEWAYS AT EACH LOT ARE NOT SHOWN,
BUT ASSUMED TO BE 400 SF EACH.
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1, = 1 00'
~
0 100
DRAINAGE MANAGEMENT AREAS
LA COSTA TOWN SQUARE
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I LOW IMPACT DEVELOPMENT AND HYDROMODIFICATION ANALYSIS WORKSHEEl
(see exhibit for DMA delineations)
I Bioretention Runoff Area x Runoff Surface Surface Subsurface
Basin DMA 1 Area, sf Factor Factor, sf Area, sf Volume, cf Volume, cf
BMP1 Roofs 8,740 1.0 8,740
I Driveways 2,000 1.0 2,000
Streets 6,013 1.0 6,013
Sidewalks 0 1.0 0
Landscaping 18,004 0.1 1,800
I Total 34,757 18,553 2,969 2,473 1,781
Bioretention Runoff Area x Runoff Surface
I Basin DMA 2 Area, sf Factor Factor, sf Area, sf
BMP2 Roofs 6,438 1.0 6,438
Driveways 0 1.0 0
Streets 3,906 1.0 3,906
I Sidewalks 103 1.0 103
Landscaping 16,304 0.1 1,630
Total 26,751 12,077 1,932 1,610 1,159
I Bioretention Runoff Area x Runoff Surface
Basin DMAJ Area, sf Factor Factor, sf Area, sf
BMP3 Roofs 10,017 1.0 10,017
I Driveways 2,200 1.0 2,200
Streets 2,514 1.0 2,514
Sidewalks 2,292 1.0 2,292
Landscaping 30,545 0.1 3,055
I Total 47,568 20,078 3,212 2,676 1,927
Bioretention Runoff Area x Runoff Surface
I Basin DMA4 Area, sf Factor Factor, sf Area, sf
BMP4 Roofs 4,836 1.0 4,836
Driveways 1,200 1.0 1,200
Streets 2,912 1.0 2,912
I Sidewalks 0 1.0 0
Landscaping 21,108 0.1 2,111
Total 30,056 11,059 1,769 1,474 1,062
I Pervious Runoff Area x Runoff Surface
Paving DMA5 Area, sf Factor Factor, sf Area, sf
BMP5 Roofs 25,001 1.0 25,001
Driveways 7,400 1.0 7,400 I Streets 20,959 1.0 20,959
Sidewalks 5,297 1.0 5,297
Landscaping 34,686 0.1 3,469
Total
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93,343 62,126 9,940 8,281 5,964
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Section 7 Hydromodification Management Plan
Table 7-4 Srzing Factors for Flow-Through Planters
Lower Flow Soil Group Slope Rain Gauge A v, v, Threshold
0.302 D Moderate Oceanside 0.090 0.0750 0.0540
0.302 D Steep Oceanside 0.070 0.0583 0.0420
0.302 A Flat L Wohlford N/A N/A N/A
0.302 A Moderate L Wohlford N/A N/A N/A
0.302 A Steep L Wohlford N/A N/A N/A
0.302 B Flat L Wohlford N/A N/A N/A
0.302 B Moderate L Wohlford N/A N/A N/A
0.302 B Steep L Wohlford N/A N/A N/A
0.302 c Flat L Wohlford 0.085 0.0708 0.0510
0.302 c Moderate L Wohlford 0.085 0.0708 0.0510
0.302 c Steep L Wohlford 0.060 0.0500 0.0360
0.302 D Flat L Wohlford 0.065 0.0542 0.0390
0.302 D Moderate L Wohlford 0.065 0.0542 0.0390
0.302 D Steep L Wohlford 0.050 0.0417 0.0300
0.102 A Flat Lindbergh N/A N/A N/A
0.102 A Moderate Lindbergh N/A N/A N/A
0.102 A Steep Lindbergh N/A N/A N/A
0.102 B Flat Lindbergh N/A N/A N/A
0.102 B Moderate Lindbergh N/A N/A N/A
0.102 B Steep Lindbergh N/A N/A N/A
0.1Q2 c Flat Lindbergh 0.250 0.2083 0.1500
0.1Q2 c Moderate Lindbergh 0.250 0.2083 0.1500
0.102 c Steep Lindbergh 0.185 0.1542 0.1110
0.102 D Flat Lindbergh 0.200 0.1667 0.1200
0.102 D Moderate Lindbergh 0.200 0.1667 0.1200
0.102 D Steep Lindbergh 0.130 0.1083 0.0780
0.102 A Flat Oceanside N/A N/A N/A
0.1Q2 A Moderate Oceanside N/A N/A N/A
0.102 A Steep Oceanside N/A N/A N/A
0.1Q2 B Flat Oceanside N/A N/A N/A
0.1Q2 B Moderate Oceanside N/A N/A N/A
0.102 B Steep Oceanside N/A N/A N/A
0.102 c Flat Oceanside 0.190 0.1583 0.1140
0.1Q2 c Moderate Oceanside 0.190 0.1583 0.1140
0.102 c Steep Oceanside 0.140 0.1167 0.0840
0.102 D Flat Oceanside 0.160 0.1333 0.0960
0.1Q2 D Moderate Oceanside 0.160 0.1333 0.0960
0.102 D Steep Oceanside 0.105 0.0875 0.0630
0.102 A Flat L Wohlford N/A N/A N/A
7-13
Use of contents on lh1s sheet IS subject to the l~mitations spec1f1ed at the end of this document
S·\Projects\San Diego County\133904-SDCo Hydromod Management Plan'WP\HMP,Q9 Final HMP _Mar2011\104720_FINAL San D1ego HMP _Mar20 11 docx
-- - - - --
33" 5' 14"
33" 4' 52"
Map Scale: 1:4,910 if printed on A size (8.5" x 11") sheel
N ---==:::~~------======Meters A 300 0 50 100 200
~---~===~~-------~=======~Feet 0 250 500 1 ,000 1 ,500
USDA Natural Resources ~ Conservation Service
Web Soil Survey
National Cooperative Soil Survey
- - ---- -
9/20/2012
Page 1 of 3
33" 5' 14"
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