HomeMy WebLinkAboutCT 04-03; La Costa Ridge 2.3 and 2.4; Storm Water Management Plan; 2005-03-22STORM WATER
MANAGEMENT PLAN
for
LA COSTA RIDGE
NEIGHBORHOODS 2.3 & 2.4
City of Carlsbad, California
Prepared for:
Real Estate Collateral Management Company
c/o Morrow Development
1903 Wright Place, Suite 180
Carlsbad, CA 92008
W.O. 2352-92
March 22, 2005
' /rm*7S?s
.R.C.E. "/Eric Mosolgo,
Water Resources Department Manager
Hunsaker & Associates San Diego, Inc.
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Att: City Engineer
Re: Storm Water Management Comments
Dear Sir,
The following comments have been reviewed and addressed
accordingly in the following manner.
d) Establish specific procedures for handling spills and routine clean up.
Special considerations and effort shall be applied to resident education on
the proper procedures for handling clean up and disposal of pollutants.
The La Costa Ridge development is a single family residential project. There
will be no communal trash storage areas as found in multi family
developments, nor will there be commercial or industrial usage of the lots
(such usage is not zoned, or permitted). "Chapter 7 - Source Control BMPs"
outlines the requirements of residents of the La Costa Ridge development
and also the responsibility of the Master Homeowners Association to inform
these residents of activities which are unlawful - including storage and
handling of household chemicals and illegal discharge to storm drains etc.
Thus a spill is an unlikely scenario.
As such Chapter 7 - Source Control BMPs addresses this requirement.
e) Ensure long-term maintenance of all post construct BMPs in perpetuity.
"Chapter 5 - Flow-Based BMPs" includes sections 5.6 Schedule of
Maintenance Activities and also 5.7 Annual Operations & Maintenance Costs.
Within these sections, annual maintenance requirements and also
maintenance costs (and responsibility for these costs) have been included.
"Chapter 9 - Fiscal Resources" has been included within the updated
SWMP's to include the funding mechanism for the BMP units also.
f) Identify how post development runoff rates and velocities from the site will
not exceed the pre-developed runoff rates and velocities to the maximum
extent practicable.
These velocities and flows have been calculated in the "Mass Grading
Hydrology Study for La Costa Greens Neighborhoods 2.1 through 2.5", dated
January, 2004 by Hunsaker & Associates San Diego, Inc. This report has
been referenced within the SWMP.
La Costa Ridge - Neighborhoods 2.3 & 2.4
Storm Water Management Plan
TABLE OF CONTENTS
CHAPTER 1 - Executive Summary
1.1 Introduction
1.2 Summary of Pre-Developed Conditions
1.3 Summary of Proposed Development
1.4 Results and Recommendations
1.5 Conclusion
CHAPTER 2 - Storm Water Criteria
2.1 Regional Water Quality Control Board Criteria
2.2 City of Carlsbad SUSMP Criteria
CHAPTER 3 - Identification of Typical Pollutants
3.1 Anticipated Pollutants from Project Site
3.2 Sediment
3.3 Nutrients
3.4 Trash & Debris
3.5 Oxygen-Demanding Substances
3.6 Oil & Grease
3.7 Bacteria and Viruses
3.8 Pesticides
CHAPTER 4 - Conditions of Concern
4.1 Receiving Watershed Descriptions
4.2 Pollutants of Concern in Receiving Watersheds
CHAPTER 5 - Flow-Based BMPs
5.1 Design Criteria
5.2 Vortechs Treatment Units
5.3 Pollutant Removal Efficiency
5.4 Maintenance Requirements
5.5 Operations and Maintenance Plan
5.6 Schedule of Maintenance Activities
5.7 Annual Operations & Maintenance Costs
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La Costa Ridge - Neighborhoods 2.3 & 2.4
Storm Water Management Plan
CHAPTER 6 - Volume-Based BMPs
6.1 Design Criteria
6.2 Extended Detention Basins
6.3 Pollutant Removal
6.4 Maintenance Requirements
CHAPTER 7 - Source Control BMPs
7.1 Landscaping
7.2 Urban Housekeeping
7.3 Automobile Use
7.4 Site Design
CHAPTER 8 - Treatment Control BMP Design (Vortechs Treatment Unit)
8.1 BMP Location
8.2 Determination of Treatment Flow
8.3 Vortechs Treatment Unit Selections
CHAPTER 9 - Fiscal Resources
9.1 Fiscal Mechanism Selection
9.2 Agreements (Mechanisms to Assure Maintenance)
CHAPTER 10 - References
BMP LOCATION EXHIBIT (pocket)
List of Tables and Figures
Chapter 1 - Watershed Map
Chapter 2 - Storm Water Requirements Applicability Checklist
Chapter 3 - Pollutant Category Table
Chapter 4 - Combined 1998 and Draft 2002 Section 303(d) Update
Chapter 4 - Beneficial Uses of Inland Surface Waters
Chapter 4 - Water Quality Objectives
Chapter 5 - Pollutant Removal Efficiency Table (Flow-Based BMPs)
Chapter 8 - 85th Percentile Rainfall Isopluvial Map
Chapter 8 - Design Runoff Determination Spreadsheets
Chapter 8 - Vortechs System Data
Chapter 9 - Maintenance Mechanism Selection Table
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I
La Costa Ridge - Neighborhoods 2.3 & 2.4
Storm Water Management Plan
CHAPTER 1 - EXECUTIVE SUMMARY
1.1 -Introduction
The La Costa Ridge Neighborhoods 2.3 & 2.4 project site is located south of the
intersection of Alga Road and El Fuerte Street, south of La Costa Ridge
Neighborhoods 2.2 and 2.1 within the City of Carlsbad, California (see vicinity map
below).
Per the City of Carlsbad SUSMP, the La Costa Ridge Neighborhoods 2.3 & 2.4
project is classified as a Priority Project and subject to the City's Permanent Storm
Water BMP Requirements.
This Storm Water Management Plan (SWMP) has been prepared pursuant to
requirements set forth in the City of Carlsbad's "Standard Urban Storm Water
Mitigation Plan (SUSMP)." All calculations are consistent with criteria set forth by
the Regional Water Quality Control Board's Order No. 2001-01, and the City of
Carlsbad SUSMP.
This SWMP recommends the location and sizing of a single flow-based and single
volume-based Best Management Practice (BMP), which will treat 85th percentile
runoff prior to discharging from the development site (see BMP Location Map in this
chapter).
Furthermore, this report determines anticipated project pollutants, pollutants of
concern in the receiving watershed, recommended source control BMPs, and
methodology used for the design of flow-based and volume-based BMPs.
LA COSTA RIDGE NEIGHBORHOODS 2.3 & 2.4 VICINITY MAP
PASEO ABRAZO
COFHNT1A STREET
MASTER TENTATIVE
WAP BOUNDARY
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La Costa Ridge - Neighborhoods 2.3 & 2.4
Storm Water Management Plan
1.2 - Summary of Pre-Developed Conditions
Located in the Batiquitos watershed, the 44-acre site consists of primarily
undisturbed terrain covered with natural vegetation with portions being mass-graded,
as shown on Drawing No. 397-3A. The project site is drained by San Marcos Creek,
which flows westerly just south of the site.
The existing condition hydrologic analysis of the La Costa Ridge Neighborhoods 2.3
and 2.4 development was completed and discussed in the "Mass Grading Hydrology
Study for Villages of La Costa Neighborhoods 2.1 through 2.5" prepared by
Hunsaker & Associates San Diego, Inc. and dated January 20, 2004.
The Regional Water Quality Control Board has identified San Marcos Creek as part
of the Carlsbad Hydrologic Unit, San Marcos Hydrologic Area, and the Batiquitos
Hydrologic Subarea (basin number 904.51).
1.3 - Summary of Proposed Development
Development of the La Costa Ridge Neighborhoods 2.3 & 2.4 sites will include the
construction of single-family homes as well as the associated streets, sidewalks,
landscaping and utilities. As part of the development, a dual purpose detention and
storm water quality treatment basin will be constructed to meet water quality
objectives set for the project.
A volume-based BMP will be located in the vicinity of the site discharge location
within Neighborhoods 2.4. The 85th percentile runoff will be treated in the proposed
dual purpose detention and storm water quality treatment basin prior to discharging
into the receiving drainage system.
Runoff from Neighborhood 2.3 will be treated via a flow-based treatment unit. A
small portion of the adjacent La Costa Ridge Neighborhood 2.2 is also treated via
this BMP unit.
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i i i i t i i i Et t 1 hi I i
WATERSHED MAP FOB
LA COSTA RIDGE
CITY OF CARLSBAD. CALIFORNIA
La Costa Ridge - Neighborhoods 2.3 & 2.4
Storm Water Management Plan
1.4 - Results and Recommendations
Table 1 below summarizes rational method 85th percentile calculations for the
proposed water quality treatment unit for the La Costa Ridge Neighborhood 2.3
development.
Table 1 - Developed Conditions 85th Percentile Calculations
Treatment Unit
Location
Corinthia Street
(Neighborhood 2.3)
Drainage
Area
(acres)
42.6
Rainfall
Intensity
(inches/hour)
0.2
Runoff
Coefficient
0.54*
85th
Percentile
Flow (cfs)
4.56
*=weighted C coefficient - See Chapter 8
Rational Method calculations predicted an 85th percentile runoff flow of
approximately 4.56 cfs for the proposed residential development.
A single Vortechs Model 7000 treatment unit (or an approved, equivalent flow
based treatment unit) with a treatment flow capacity of 11 cfs is recommended.
The proposed Vortechnics treatment unit (or an approved, equivalent flow based
treatment unit) will be an offline pre-cast treatment unit. The 85th percentile design
flow rate is forced into the treatment area by a diversion weir built in the upstream
junction. Flows in excess of the design flow rate pass over the weir and proceed
downstream.
The detention/water quality basin located in Neighborhood 2.4 has been sized to
accommodate both the role of storm water quality and that of a detention basin, with
the first 3 feet of storage capacity allocated solely to the treatment of storm water.
For calculations and further description of the storm water quality basin in
Neighborhood 2.4, refer to the "Mass Grading Hydrology Study for Villages of La
Costa Neighborhoods 2.1 through 2.5", Hunsaker & Associates San Diego, Inc.,
January, 2004.
1.5-Conclusion
The combination of proposed construction and permanent BMP's will reduce, to the
maximum extent practicable, the expected project pollutants and will not adversely
impact the beneficial uses of the receiving waters.
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NEIGHBORHOOD 2.4
WATER QUALITY
TREATMENT BASIN . , ,- / .-'/<' y.
LEGEND
PREPARED BY:
WATERSHED BOUNDARY
WATER QUALITY UNIT LA COSTA RIDGE
NEIGHBORHOODS 2.3 AND 2.4
CITY OF CARLSBAD, CALIFORNIA
II
La Costa Ridge - Neighborhoods 2.3 & 2.4
Storm Water Management Plan
CHAPTER 2 - STORM WATER CRITERIA
2.1 - Regional Water Quality Control Board Criteria
All runoff conveyed in the proposed storm drain systems will be treated in
compliance with Regional Water Quality Control Board regulations and NPDES
criteria prior to discharging to natural watercourses. California Regional Water
Quality Control Board Order No. 2001-01, dated February 21, 2001, sets waste
discharge requirements for discharges of urban runoff from municipal storm
separate drainage systems draining the watersheds of San Diego County.
Per the RWQCB Order, post-development runoff from a site shall not contain
pollutant loads which cause or contribute to an exceedance of receiving water
quality objectives or which have not been reduced to the maximum extent
practicable. Post-construction Best Management Practices (BMPs), which refer to
specific storm water management techniques that are applied to manage
construction and post-construction site runoff and minimize erosion, include source
control - aimed at reducing the amount of sediment and other pollutants - and
treatment controls that keep soil and other pollutants onsite once they have been
loosened by storm water erosion.
Post construction pollutants are a result of the urban development of the property
and the effects of automobile use. Runoff from paved surfaces can contain both
sediment (in the form of silt and sand) as well as a variety of pollutants transported
by the sediment. Landscape activities by homeowners are an additional source of
sediment.
All structural BMPs shall be located to infiltrate, filter, or treat the required runoff
volume or flow (based on the 85th percentile rainfall) prior to its discharge to any
receiving watercourse supporting beneficial uses.
2.2 - City of Carlsbad SUSMP Criteria
Per the City of Carlsbad SUSMP, the La Costa Ridge Neighborhoods 2.3 & 2.4
project is classified as a Priority Project and subject to the City's Permanent Storm
Water BMP Requirements. These requirements required the preparation of this
Storm Water Management Plan.
The Storm Water Applicability Checklist, which must be included along with Grading
Plan applications, is included on the following page.
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Storm Water Standards
4/03/03
VI; RESOURCES^ REFERENCES:
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 Project Permanent Storm Water BMP Requirements.
Does the project meet the definition of one or more of the priority project
categories?* .
1 . Detached residential development of 1 0 or more units
2. Attached residential development of 1 0 or more units
3. Commercial development greater than 1 00,000 square feet
4. Automotive repair shop
5. Restaurant
6. Steep hillside development greater than 5,000 square feet
7. Project discharging to receiving waters within Environmentally Sensitive Areas
8. Parking lots greater than or equal to 5,000 ft* or with at least 15 parking spaces, and
potentially exposed to urban runoff
9. Streets, roads, highways, and freeways which would create a new paved surface that is
5,000 square feet or greater
Yes
f
J
y
No
%/
^x/
v/
S
J
*/
* Refer to the definitions section in the Storm Water Standards tor 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 ail answers to Part A are "No",
continue to Part B.
30
Storm Water Standards
4/03/03
Part B: Determine Standard Permanent Storm Water Requirements.
Does the project propose:
1 . New impervious areas, such as rooftops, roads, parking lots, driveways, paths and
sidewalks?
2. New pervious landscape areas and irrigation systems?
3. Permanent structures within 1 00 feet of any natural water body?
4. Trash storage areas?
5. Liquid or solid material loading and unloading areas?
6. Vehicle or equipment fueling, washing, or maintenance areas?
7. Require a General NPDES Permit for Storm Water Discharges Associated with
Industrial Activities (Except construction)?*
8. Commercial or industrial waste handling or storage, excluding typical office or
household waste?
9. Any grading or ground disturbance during construction?
1 0. Any new storm drains, or alteration to existing storm drains?
Yes
v/
\/
y
s
No
S
S
••"
S
y
*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:
If the answer to 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 D, below.
Part C: Determine Construction Phase Storm Water Requirements.
Would the project meet any of these criteria during construction?
1 . is the project subject to California's statewide General NPDES Permit for Storm Water
Discharges Associated With Construction Activities?
2. Does the project propose grading or soil disturbance?
3. Would storm water or urban runoff have the potential to contact any portion of the
construction area, including washing and staging areas?
4. 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)?
Yes
V/
v/s
y
No
-
31
Storm Water Standards
4/03/03
PartD: 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
1) Projects where the site is 50 acres or more and grading will occur during the
rainy season
2) Projects 5 acres or more. 3) Projects 5 acres or more within or directly
adjacent to or discharging directly to a coastal lagoon or other receiving water
within an environmentally sensitive area
Projects, active or inactive, adjacent or tributary to sensitive water bodies
Q B) Medium Priority
1) 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.)
2) 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.
3) Permit projects on private property where grading permits are required,
however, Notice Of Intents (NOIs) and SWPPPs are not required.
Q C; Low Priority
1) Capital Projects where minimal to no grading occurs, such as signal light and
loop installations, street light installations, etc.
2) Permit projects in the public right-of-way where minimal to no grading occurs,
such as pedestrian ramps, driveway additions, small retaining walls, etc.
3) Permit projects on private property where grading permits are not required,
such . as small retaining walls,, single-family homes, small tenant
improvements, etc.
32
Ill
La Costa Ridge - Neighborhoods 2.3 & 2.4
Storm Water Management Plan
CHAPTER 3 - IDENTIFICATION OF TYPICAL POLLUTANTS
3.1 - Anticipated Pollutants from Project Site
The following table details typical anticipated and potential pollutants generated by
various land use types. The La Costa Ridge Neighborhoods 2.3 & 2.4 development
will consist of detached single-family residences. Thus, the Detached Residential
Development category has been highlighted to clearly illustrate which general
pollutant categories are anticipated from the project area.
Priority
Project
Categories
f >, Detached-,-j-» ' -if'las^l
Oeveloprrittit
Attached
Residential
Development
Commercial
Development
>1 00,000 ft2
Automotive
Repair
Shops
Restaurants
Hillside
Development
>5,000 ft2
Parking Lots
Streets,
Highways &
Freeways
Retail Gas
Outlets
General Pollutant Categories
J2cO
•50!
CO
feSji
X
pd)
X
pO)
X
"c0)
3
Z
"•"""AS?
Wd
X
p(1)
X
po,
pd)
>, w> reIB **
X 5
X
X
X
X
to•O
.alC Q.IB pCD £t? 0O 0
ia9«^vV
p(2)
X(4)(5)
X(4)
X(4)
o«
"w S2 IB1- Q
^' 'S
^r
X
X
X
X
X
X
X
X
o> %f 0).= u(-"DC
» S ™o> 2 w>. E .QX 0) 3
O Q (O
p(i)
p(5)
X
X
p(1)
p(5)Grease00
J^O
t^^ffi^l^Fft''
p(2)
X
X
X
X
X
X
X
oet
^2 to
U 3n .hm >
^Rf
p
p(3)
X
100)•o
'5
4^100)
Q.
*$«?$?'
X
p(5)
X
pd)
X = anticipated
P = potential
(1) A potential pollutant if landscaping exists on-site.
(2) A potential pollutant if the project includes uncovered parking areas.
(3) A potential pollutant if land use involves food or animal waste products.
(4) Including petroleum hydrocarbons.
(5) Including solvents.
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La Costa Ridge - Neighborhoods 2.3 & 2.4
Storm Water Management Plan
3.2 - Sediment
Soils or other surface materials eroded and then transported or deposited by the
action of wind, water, ice, or gravity. Sediments can increase turbidity, clog fish gills,
reduce spawning habitat, smother bottom dwelling organisms, and suppress aquatic
vegetative growth.
3.3 - Nutrients
Inorganic substances, such as nitrogen and phosphorous, that commonly exist in the
form of mineral salts that are either dissolved or suspended in water. Primary
sources of nutrients in urban runoff are fertilizers and eroded soils. Excessive
discharge of nutrients to water bodies and streams can cause excessive aquatic
algae and plant growth. Such excessive production, referred to as cultural
eutrophication, may lead to excessive decay of organic matter in the water body,
loss of oxygen in the water, release of toxins in sediment, and the eventual death of
aquatic organisms.
3.4 - Trash & Debris
Examples include paper, plastic, leaves, grass cuttings, and food waste, which may
have a significant impact on the recreational value of a water body and aquatic
habitat. Excess organic matter can create a high biochemical oxygen demand in a
stream and thereby lower its water quality. In areas where stagnant water is
present, the presence of excess organic matter can promote septic conditions
resulting in the growth of undesirable organisms and the release of odorous and
hazardous compounds such as hydrogen sulfide.
3.5 - Oxygen-Demanding Substances
Biodegradable organic material as well as chemicals that react with dissolved
oxygen in water to form other compounds. Compounds such as ammonia and
hydrogen sulfide are examples of oxygen-demanding compounds. The oxygen
demand of a substance can lead to depletion of dissolved oxygen in a water body
and possibly the development of septic conditions.
3.6 - Oil & Grease
Characterized as high high-molecular weight organic compounds. Primary sources
of oil and grease are petroleum hydrocarbon products, motor products from leaking
vehicles, oils, waxes, and high-molecular weight fatty acids. Elevated oil and grease
content can decrease the aesthetic value of the water body, as well as the water
quality.
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La Costa Ridge - Neighborhoods 2.3 & 2.4
Storm Water Management Plan
3.7 - Bacteria and Viruses
Bacteria and viruses are ubiquitous micro-organisms that thrive under certain
environmental conditions. Their proliferation is typically caused by the transport of
animals or human fecal wastes from the watershed. Water, containing excessive
bacteria and viruses can alter the aquatic habitat and create a harmful environment
for humans and aquatic life. Also, the decomposition of excess organic waste
causes increased growth of undesirable organisms in the water.
3.8 - Pesticides
Pesticides (including herbicides) are chemical compounds commonly used to control
nuisance growth or prevalence of organisms. Excessive application of a pesticide
may result in runoff containing toxic levels of its active component.
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IV
La Costa Ridge - Neighborhoods 2.3 & 2.4
Storm Water Management Plan
CHAPTER 4 - CONDITIONS OF CONCERN
4.1 - Receiving Watershed Descriptions
As shown in the watershed map on the following page, the pre-developed and post-
developed La Costa Ridge site drains to the San Marcos Creek watershed.
The Regional Water Quality Control Board has identified San Marcos Creek as part
of the Carlsbad Hydrologic Unit, San Marcos Hydrologic Area, and the Batiquitos
Hydrologic Subarea (basin number 904.51).
4.2 - Pollutants of Concern in Receiving Watersheds
San Marcos Creek is not listed on the EPA's 303(d) List of endangered waterways
(included in this Chapter). Per the "Water Quality Plan for the San Diego Basin", the
beneficial uses for San Marcos Creek include agricultural supply,.contact water
recreation, non-contact recreation, warm freshwater habitat, and wildlife habitat. In
addition, San Marcos Creek is exempted as being designated as a Municipal water
supply.
Table 3-3 from the "Water Quality Plan for the San Diego Basin" (included at the end
of this Chapter) lists water quality objectives for a variety of potential pollutants
required to sustain the beneficial uses of the San Marcos hydrologic area.
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i j i i 11 t I II i i i i i I i i i i *
26 Los Monos HSA
(904.31)
27 Los Monos HSA
(904.31)
28 San Marcos HA
(904.50)
29 Escondido Creek
HA (904.60)
30 San Elijo HSA
(904.61)
31 San Dieguito HU
(905.00)
32 Del Dios HSA
(905.21 and
905.22)
33 Del Dios HSA
(905.21)
34 Felicita HSA
(905.23)
35 Felicita HSA
(905.23)
36 Highland HSA
(905.32)
37 Sutherland HSA
(905.53)
38 Miramar Reservoir
HA (906. 10)
39 Miramar Reservoir
HA (906.10)
40 Scripps HA
(906.30)
Agua Hedionda
Lagoon
Agua Hedionda
Creek
Pacific Ocean
Shoreline
Pacific Ocean
Shoreline
San Elijo
Lagoon
Pacific Ocean
Shoreline
Green Valley
Creek
Hodges
Reservoir
Felicita Creek
Kit Carson
Creek
Cloverdale
Creek
Sutherland
Reservoir
Los
Penasquitos
Lagoon
Pacific Ocean
Shoreline
Pacific Ocean
Shoreline
lower portion
at Moonlight State Beach
at San Elijo Lagoon
at San Dieguito Lagoon Mouth
Entire Reservoir
should in 905.21 HSA
Entire Reservoir
Entire Lagoon
Torrey Pines State Beach at Del
Mar (Anderson Canyon)
La Jolla Shores Beach at El Paseo
Grande
La Jolla Shores Beach at Caminito
Del Oro
La Jolla Shores Beach at
Vallecitos
La Jolla Shores Beach at Ave de la
Playa
Bacterial
lndicatorsE
Sedimentation /
Siltation
Total Dissolved
Solids
Bacterial
lndicatorsE
Bacterial
lndicatorsE
Bacterial
lndicatorsE
Eutrophic
Sedimentation /
Siltation
Bacterial
lndicatorsE
Sulfate
Color
Nitrogen
Phosphorus
Total Dissolved
Solids
Total Dissolved
Solids
Total Dissolved
Solids
Phosphorus
Total Dissolved
Solids
Color
Sedimentation /
Siltation
Bacterial
Indicators6
Bacterial
lndicatorsE
6.8 acres
lower 7 miles
0.4 miles
0.44 miles
150 acres
330 acres
150 acres
0.86 miles
1 mile
Entire
Reservoir
(11 04 acres)
lower 0.92
miles
1 mile
1 .2 miles
Entire
Reservoir
469 acres
0.4 miles
3.9 miles
1998
2002
1998
1998
1998
1998
2002
2002
2002
2002
2002
2002
1998
2002
1998
last updated 9/23/2003
S:\WQS\303dlist\SD Staff Report-2002\FINAL VERSIONSMJsted Waterbodies-2002.xls\Table 4 (SepOS page 3 of 6
Table 2-2. BENEFICIAL USES OF INLAND SURFACE WATERS
1,2
Inland Surface Waters Hydrologic Unit
Basin Number
BENEFICIAL USE
M
U
N
A
G
R
I
N
D
P
R
0
C
G
W
R
F
R
S
H
P
O
W
R
E
C
1
R
E
C
2
B
I
0
L
W
A
R
M
C
0
L
D
W
I
L
D
R
A
R
E
S
P
W
N
San Diego County Coastal Streams - continued
Buena Vista Lagoon
Buena Vista Creek
Buena Vista Creek
Agua Hedlonda
Agua Hedionda Creek
Buena Creek
Agua Hedionda Creek
Letterbox canyon
Canyon de las Encinas
4.21
4.22
4.21
4.31
4.32
4.32
4.31
4.31
4.40
See Coastal Waters- Table 2-3
+
+
•
•
•
•
•
•
•
•
•
•
•
••
See Coastal Waters- Table 2-3
•
•
•
•
+
•
•
•
•
•
•
•
•'
•
•
•
•
O
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
San Marcos Creek Watershed
Batiquitos Lagoon
San Marcos Creek
unnamed intermittent streams
4.51
4.52
4.53
See Coastal Waters- Table 2-3
+
+
•
•
•
•
•
•
•
•
•
•
San Marcos Creek Watershed
San Marcos Creek
Encinitas Creek
4.51
4.51
+
+
•
•
•
•
•
•
•
•
•
•
• Existing Beneficial Use
0 Potential Beneficial Use
+ Excepted From MUN (See Text)
Waterbodies are listed multiple times if they cross hydrologic area or sub area boundaries.
I
' Beneficial use designations apply to all tributaries to the indicated waterbody, if not listed separately.
Table 2-2
BENEFICIAL USES
March 12, 1997
2-27
Table 2-3. BENEFICIAL USES OF COASTAL WATERS
Coastal Waters
Pacific Ocean
Dana Point Harbor
Del Mar Boat Basin
Mission Bay
Oceanside Harbor
San Diego Bay 1
Hydrologic
Unit Basin
Number
BENEFICIAL USE
I
N
D
•
N
A
V
R
E
C
1
•
R
E
C
2
•
C
0
M
M
•
B
I
0
L
E
S
T
•
W
I
L
D
•
•
•
•
R
A
R
E
•
•
•
•
M
A
R
•
•
•
•
A
Q
U
A
M
1
G
R
•
•
•
•
•
S
P
W
N
•
•
• '
•
•
W
A
R
M
S
H
E
L
L
•
•
•
•
•
•
Coastal Lagoons
Tijuana River Estuary
Mouth of San Diego River
2Los Penasquitos Lagoon
San Dieguito Lagoon
Batiquitos Lagoon
San Elijo Lagoon
Aqua Hedionda Lagoon
11. 11
7.11
6.10
5.11
4.51
5.61
4.31 •
•
•
•
•
•
•
•
•
•
•
•
•
•
•
••••
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
1 Includes the tidal prisms of the Otay and Sweetwater Rivers.
2 Fishing from shore or boat permitted, but other water contact recreational (REC-1} uses are prohibited.
• Existing Beneficial Use
March 12, 1997
Table 2-3
BENEFICIAL USES 2-47
Table 3-2. WATER QUALITY OBJECTIVES
Concentrations not to be exceeded more than 10% of the time during any one one year period.
Inland Surface Waters Hydrologic
Unit Basin
Number
Constitiuent (mg/L or as noted)
TDS Cl so4 %Na N&P Fe Mn MBAS B ODOR Turb
NTU
Color
Units f
SAN LUIS REY HYDROLOGIC UNIT 903.00
Lower San Luis HA
Monserat HA
Warner Valley HA
3.10
3.20
3.30
500
500
500
250
250
250
250
250
250
60
60
60
a
a
a
0.3
0.3
0.3
0.05
0.05
0.05
0.5
0.5
0.5
0.75
0.75
0.75
none
none
none
20
20
20
20
20
20
1.0
1.0
1.0
CARLSBAD HYDROLOGIC UNIT 904.00
Loma Alta HA
Buena Vista Creek HA
Agua Hedionda HA
Encinas HA
San Marcos HA
Escondido Creek HA
4.10
4.20
4.30
4.40
4.50
4.60
-
500
500
-
500
500
-
250
250
-
250
250
-
250
250
-
250
250
-
60
60
-
60
60
-
a
a
-
a
a
-
0.3
0.3
-
0.3
0.3
-
0.05
0.05
-
0.05
0.05
-
0.5
0.5
-
0.5
0.5
-
0.75
0.75
-
0.75
0.75
none
none
none
none
none
none
20
20
20
20
20
20
20
20
20
20
20
20
1.0
1.0
1.0
1.0
1.0
1.0
SAN DIEGUITO HYDROLOGIC UNIT 905.00
Solana Beach HA
Hodges HA
San Pasqual HA
Santa Maria Valley HA
Santa Ysabel HA
5.10
5.20
5.30
5.40
5.50
500
500
500
500
500
250
250
250
250
250
250
250
250
250
250
60
60
60
60
60
a
a
a
a
a
0.3
0.3
0.3
0.3
0.3
0.05
0.05
0.05
0.05
0.05
0.5
0.5
0.5
0.5
0.5
0.75
0.75
0.75
0.75
0.75
none
none
none
none
none
20
20
20
20
20
20
20
20
20
20
1.0
1.0
1.0
1.0
1.0
PENASQUITOS HYDROLOGIC UNIT 906.00
Miramar Reservoir HA
Poway HA
6.10
6.20
500
500
250
250
250
250
60
60
a
a
0.3
0.3
0.05
0.05
0.5
0.5
0.75
0.75
none
none
20
20
20
20
1.0
1.0
HA - Hydrologic Area
HSA - Hydrologic Sub Area (Lower case letters indicate endnotes following the table.)
Table 3-2
WATER QUALITY OBJECTIVES Page 3-23 September 8, 1994
V
La Costa Ridge - Neighborhoods 2.3 & 2.4
Storm Water Management Plan
CHAPTER 5 - FLOW-BASED BMPS
5.1 - Design Criteria
Flow-based BMPs shall be designed to mitigate the maximum flowrate of runoff
produced from a rainfall intensity of 0.2 inch per hour. Such BMPs utilize either
mechanical devices (such as vaults that produce vortex effects) or non-mechanical
devices (based on weir hydraulics and specially designed filters) to promote settling
and removal of pollutants from the runoff.
Per the request of the City of Carlsbad, 85th percentile flow calculations were
performed using the Rational Method. The basic Rational Method runoff procedure
is as follows:
Design flow (Q) = C * I * A
Runoff Coefficient I - In accordance with the County of San Diego standards, the
weighted runoff coefficient for all the areas draining to the treatment unit was
determined using the areas analyzed in the final engineering hydrology report. The
runoff coefficient is based on the following characteristics of the watershed:
Land Use - Single Family Residential in Developed Areas
Soil Type - Hydrologic soil group D was assumed for all areas. Group
D soils have very slow infiltration rates when thoroughly wetted.
Consisting chiefly of clay soils with a high swelling potential, soils with a
high permanent water table, soils with clay pan or clay layer at or near
the surface, and shallow soils over nearly impervious materials, Group
D soils have a very slow rate of water transmission.
Rainfall Intensity (I) - Regional Water Quality Control Board regulations and NPDES
criteria have established that flow-based BMPs shall be designed to mitigate a
rainfall intensity of 0.2 inch per hour.
Watershed Area (A) - Corresponds to total area draining to treatment unit.
5.2 - Vortechs Treatment Units
The Vortechs Storm Water Treatment System is designed to efficiently remove grit,
contaminated sediments, metals, hydrocarbons and floating contaminants from
surface runoff. Combining swirl-concentrator and flow-control technologies to
eliminate turbulence within the system, the Vortechs System ensures the effective
capture of sediment and oils and prevents resuspension of trapped pollutants for
flows up to 25 cfs.
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La Costa Ridge - Neighborhoods 2.3 & 2.4
Storm Water Management Plan
Other features of the Vortechs Systems include the following:
Large capacity system provides an 80 percent net annual Total
Suspended Solids (TSS) removal rate.
Unit is installed below grade.
Low pump-out volume and one-point access reduce maintenance costs.
Design prevents oils and other floatables from escaping the system
during cleanout.
Enhanced removal efficiencies of nutrients and heavy metals with offline
configuration.
The tangential inlet to the system creates a swirling motion that directs settleable
solids into a pile towards the center of the grit chamber. Sediment is caught in the
swirling flow path and settles back onto the pile after the storm event is over.
Floatable entrapment is achieved by sizing the low flow control to create a rise in the
water level of the vault that is sufficient to just submerge the inlet pipe with the 85th
percentile flow.
5.3 - Pollutant Removal Efficiency Table
Pollutant of Concern
Sediment
Nutrients
Heavy Metals
Organic Compounds
Trash & Debris
Oxygen Demanding Substances
Bacteria
Oil & Grease
Pesticides
BMP Categories
Hydrodynamic
Separation
Devices'2'
M-H
L-M
L-M
L-M
M-H
L
L
L-H
L
' '' -
• ;M^4it%Hfc
• ">'•
•
(1) The County will periodically assess the performance characteristics of these BMPs to
update this table.
(2) Proprietary Structural BMPs. Not all serve the same function.
L (Low): Low removal efficiency (roughly 0-25%)
M (Medium): Medium removal efficiency (roughly 25-75%)
H (High): High removal efficiency (roughly 75-100%)
U: Unknown removal efficiency, applicant must provide evidence supporting use
Sources: Guidance Specifying Management Measures for Sources of Nonpoint Pollution in
Coastal Waters (1 993), National Stormwater Best Management Practices Database (2001 ),
and Guide for BMP Selection in Urban Developed Areas (2001).
DE:DE h:\sw qualityl2352\92 ridge 2.3 & 2.4\swmp-tm-05.doc
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La Costa Ridge - Neighborhoods 2.3 & 2.4
Storm Water Management Plan
5.4 - Maintenance Requirements
Flow-based storm water treatment devices should be inspected periodically to
assure their condition to treat anticipated runoff. Maintenance of the proposed
Vortechnics units includes inspection and maintenance 1 to 4 times per year.
Maintenance of the Vortechs units involves the use of a "vactor truck", which clears
the grit chamber of the treatment unit by vacuuming all the grit, oil and grease, and
water from the sump. Typically a 3-man crew is required to perform the
maintenance of the treatment unit. Properly maintained Vortechs Systems will only
require evacuation of the grit chamber portion of the system. In some cases, it may
be necessary to pump out all chambers. In the event of cleaning other chambers, it
is imperative that the grit chamber be drained first.
Proper inspection includes a visual observation to ascertain whether the unit is
functioning properly and measuring the amount of deposition in the unit. Floatables
should be removed and sumps cleaned when the sump storage exceeds 85 percent
of capacity specifically, or when the sediment depth has accumulated within 6 inches
of the dry-weather water level. The rate at which the system collects pollutants will
depend more heavily on site activities than the size of the unit.
Maintenance of the site BMPs will be the responsibility of the Homeowners
Association. A maintenance plan will be developed and will include the following
information:
Specification of routine and non-routine maintenance activities to be
performed
A schedule for maintenance activities
Name, qualifications, and contact information for the parties responsible for
maintaining the BMPs
For proper maintenance to be performed, the storm water treatment facility must be
accessible to both maintenance personnel and their equipment and materials.
5.5 - Operations and Maintenance Plan
The operational and maintenance needs of a Vortechs unit include:
Inspection of structural integrity and screen for damage.
Animal and vector control.
Periodic sediment removal to optimize performance.
Scheduled trash, debris and sediment removal to prevent obstruction.
The facility will be inspected regularly and inspection visits will be completely
documented:
DE:DE h:\sw quallty\2352\92 ridge 2.3 & 2 4\swtnp-tm-05.doc
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La Costa Ridge - Neighborhoods 2.3 & 2.4
Storm Water Management Plan
Preventive maintenance activities for a flow-based treatment unit are:
Trash and Debris Removal - trash and debris accumulation will be monitored
during both the dry and wet season and after every large storm event (rainfall
events in excess of 1 inch). Trash and debris will be removed from the
Vortechs unit annually (at the end of the wet season). Trash and debris will
also be removed when material accumulates to 85% of the unit's sump
capacity, or when the floating debris is 12 inches deep (whichever occurs
first).
Sediment Removal - sediment accumulation will be monitored during both the
wet and dry season, and after every large storm (1.0 inch). Sediment will be
removed from the Vortechs unit annually (at the end of the wet season).
Sediment will also be removed when material accumulates to 85% of the
unit's sump capacity, or when the floating debris is 12 inches deep (whichever
occurs first). Disposal of sediment will comply with applicable local, county,
state or federal requirements.
Corrective maintenance is required on an emergency or non-routine basis to
correct problems and to restore the intended operation and safe function of a
Vortechs unit. Corrective maintenance activities include:
Removal of Debris and Sediment
Structural Repairs - Once deemed necessary, repairs to structural
components of a Vortechs unit will be completed within 30 working days.
Qualified individuals (i.e., the manufacturer representatives) will conduct
repairs where structural damage has occurred.
5.6 - Schedule of Maintenance Activities
Target Maintenance Frequency-At a minimum, treatment unit should be cleaned
annually.
Maintenance Activity - Annual inspection and cleanout
Clear grit chamber unit with vactor truck.
Perform visual inspection
Remove floatables
DE:DE h:\sw qual|ty\2352\82 ridge 2.3 & 2.4\swmp-tm-05.doc
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La Costa Ridge - Neighborhoods 2.3 & 2.4
Storm Water Management Plan
5.7 - Annual Operations & Maintenance Costs
The following costs are intended only to provide a magnitude of the costs involved in
maintaining BMPs. Funding shall be provided by the Master Home Owners
Association for the La Costa Ridge.
Approximate annual maintenance costs for the proposed Vortechs unit are outlined
below. Costs assume a 3 man crew:
Maintenance for Vortechs Model 7000:
Periodic Inspection, Maintenance and Monitoring = $800
Annual Cleanout Cost = $1,750
Subtotal = $2,550
Contingency = $255
Total = $2,805
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VI
La Costa Ridge - Neighborhoods 2.3 & 2.4
Storm Water Management Plan
Chapter 6 - VOLUME-BASED BMPs
6.1 - Design Criteria
Volume-based BMPs shall be designed to mitigate the volume of runoff produced
from a 24-hour 85th percentile storm event, as determined from the local historical
rainfall record.
Such facilities are usually designed to store the first flush runoff event below the
principle spillway elevation (riser, weir, etc.) while providing a means for low flow
dewatering. Outlet structures will be designed to convey runoff from the 100-year
frequency storm to the basin.
Treatment should occur prior to discharge to any receiving water body supporting
beneficial uses. Shared BMPs shall be operational prior to the use of any dependent
development or phase of development.
For calculations and further description of the dual purpose detention and storm
water quality basin in Neighborhood 2.4, refer to the "Mass Grading Hydrology Study
for Villages of La Costa Neighborhoods 2.1 through 2.5", Hunsaker & Associates
San Diego, Inc., January, 2004
6.2 - Dual Purpose Detention and Water Quality Basin
The La Costa Ridge site contain a single dual purpose detention and water quality
basin - the bottom portion of the regional detention facility that operates as an
extended duration storm water quality basin. This basin will collect dry weather
runoff volume from offsite areas draining to the wetlands restoration channel.
Site runoff from Neighborhood 2.4 will be detained in the Neighborhood 2.4 basin
and will slowly dewater via the slots in the side of the 18-inch riser. After passing
through their respective risers, the runoff will flow via the 18-inch RCP to the natural
drainage course downstream.
6.3 - Pollutant Removal
As shown in the table (from the City of Carlsbad SUSMP) on the following page,
dual purpose detention and water quality basins provide the following treatment
efficiencies:
Sediment - High removal efficiency
Nutrients - Medium removal efficiency
Heavy Metals - Medium removal efficiency
Trash & Debris - High removal efficiency
Oxygen-Demanding Substances - Medium removal efficiency
Oil & Grease - Medium removal efficiency
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. *1 ;• • i > t i- I i-- i }-• I i - I i- t I ft *
Storm Water Standards
4/03/03
Table 4. Structural Treatment Control BMP Selection Matrix.
Pollutant of Concern
•
Sediment
Nutrients
Heavy Metals
Organic Compounds
Trash & Debris
Oxygen Demanding
Substances
Bacteria
Oil & Grease
Pesticides
Treatment Control BMP Categories
Blofilters
M
L
M
U
L
L
U
M
U
Detention
Basins
H
M .
M
U
H
M
U
M
U
Infiltration
Basins'1)
H
M
M
U
U
M
H
U
U
Wet Ponds or
Wetlands
H
M
H
U .
U
M
U
U
U
Drainage
Inserts
L
L
L
L
M
L
L •
L
L
Filtration
H
M
H
M
H
. M
M
H
U
Hydrodynamic
Separator Systems®
M
L
L
L
M
L
L
L
L
(1 ) Including trenches and porous pavement
(2) Also known as hydrodynamic devices and baffle boxes.
L: Low removal efficiency
M: Medium removal efficiency ^.
H: High removal efficiency
U: Unknown removal efficiency
Sources: Guidance Specifying Management Measures for Sources ofNonpoInt Pollution In Coastal Waters (1993), National
Stormwater Best Management Practices Database (2001), and Guide for BMP Selection In Urban Developed Areas (2001).
La Costa Ridge - Neighborhoods 2.3 & 2.4
Storm Water Management Plan
6.4 - Maintenance Requirements
Proper maintenance is required to insure optimum performance of the basin.
General BMP inspections should check for structural integrity of the riser, debris and
litter removal to prevent blockage of outlet orifices, etc. Fencing should be provided
at the top of the basin to serve as protection to the public from the safety hazards
inherent with standing water in the basin.
Maintenance and funding of the dual purpose detention and water quality basin will
be the responsibility of the Homeowners Association for La Costa Ridge. For proper
maintenance to be performed, the storm water treatment facility must be accessible
to both maintenance personnel and their equipment and materials.
Factors that affect the operational performance of a volume-based dual purpose
detention and water quality basin ponds include mowing, control of pond vegetation,
removal of accumulated bottom sediments, removal of debris from all inflow and
outflow structures, unclogging of orifice perforations, etc. Periodic inspections should
be performed following each significant storm. These basins should be inspected at
least twice a year to evaluate facility operation.
Periodic inspections of both dual purpose detention water quality basins should be
performed at regular intervals throughout the year. Additional inspections will be
required after major rainfall events (defined per this Maintenance Plan as 24-hour
rainfall events in excess of 1 inch).
During the periodic and post-major event rainfall inspections, the inspector must
identify any repairs and maintenance activities deemed necessary, including the
removal of trash, debris, and sediment from the upper chamber of the basin area.
All riser orifices should be unclogged during the periodic and post-rainfall
inspections.
A Registered Civil Engineer will conduct an annual inspection of each basin. This
inspection will include a thorough inspection of the basin area, outlet structure and
internal gabion structure. The engineer will identify any required repairs as well as
corrective maintenance activity required to maintain the hydraulic performance of the
basins. All sediment, trash, and debris should be removed from the upper and lower
chambers of the basin at the annual maintenance session.
Sediment removed during periodic, post-major rainfall event, and annual
maintenance can be placed in a sanitary landfill or used for composting activities. If
no basin maintenance takes places for a period of longer than 1 year, then trapped
pollutants may be deemed hazardous and special requirements may apply to
disposal activities. In such a case, removals would require testing prior to disposal in
a sanitary landfill.
DE:DE h:\swquallty\2352\92ridoe2-3i24\swmp-tm-05.doc
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VII
La Costa Ridge - Neighborhoods 2.3 & 2.4
Storm Water Management Plan
CHAPTER 7 - SOURCE CONTROL BMPS
7.1 - Landscaping
Manufactured slopes shall be landscaped with suitable ground cover or installed with
an erosion control system. Homeowners will be educated as to the proper routine
maintenance to landscaped areas including trimming, pruning, weeding, mowing,
replacement or substitution of vegetation in ornamental and required landscapes.
Per the RWQCB Order, the following landscaping activities are deemed unlawful
and are thus prohibited:
Discharges of sediment
Discharges of pet waste
Discharges of vegetative clippings
Discharges of other landscaping or construction-related wastes.
7.2 - Urban Housekeeping
Fertilizer applied by homeowners, in addition to organic matter such as leaves and
lawn clippings, all result in nutrients in storm water runoff. Consumer use of
excessive herbicide or pesticide contributes toxic chemicals to runoff. Homeowners
will be educated as to the proper application of fertilizers and herbicides to lawns
and gardens.
The average household contains a wide variety of toxins such as oil/grease,
antifreeze, paint, household cleaners and solvents. Homeowners will be educated
as to the proper use, storage, and disposal of these potential storm water runoff
contaminants.
Per the RWQCB Order, the following housekeeping activities are deemed unlawful
and are thus prohibited:
Discharges of wash water from the cleaning or hosing of impervious
surfaces including parking lots, streets, sidewalks, driveways, patios,
plazas, and outdoor eating and drinking areas (landscape irrigation and
lawn watering, as well as non-commercial washing of vehicles in
residential zones, is exempt from this restriction.).
Discharges of pool or fountain water containing chloride, biocides, or
other chemicals.
Discharges or runoff from material storage areas containing chemicals,
fuels, grease, oil, or other hazardous materials.
Discharges of food-related wastes (grease, food processing, trash bin
wash water, etc.).
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La Costa Ridge - Neighborhoods 2.3 & 2.4
Storm Water Management Plan
7.3 - Automobile Use
Urban pollutants resulting from automobile use include oil, grease, antifreeze,
hydraulic fluids, copper from brakes, and various fuels. Homeowners will be
educated as to the proper use, storage, and disposal of these potential storm water
contaminants.
Per the RWQCB Order, the following automobile use activities are deemed unlawful
and are thus prohibited:
Discharges of wash water from the hosing or cleaning of gas stations,
auto repair garages, or other types of automotive service facilities.
Discharges resulting from the cleaning, repair, or maintenance of any
type of equipment, machinery, or facility including motor vehicles,
cement-related equipment, port-a-potty servicing, etc.
Discharges of wash water from mobile operations such as mobile
automobile washing, steam cleaning, power washing, and carpet
cleaning.
The Homeowners Association will make all homeowners aware of the
aforementioned RWQCB regulations through a homeowners' education program.
7.4-Site Design BMPs
Priority projects, such as the La Costa Ridge Neighborhood 2.3 & 2.4 project, shall
be designed to minimize, to the maximum extent practicable the introduction of
pollutants and conditions of concern that may result in significant impact, generated
from site runoff to the storm water conveyance system. Site design components can
significantly reduce the impact of a project on the environment. The following design
techniques have been proposed to accomplish this goal.
- Implementing on-lot hydrologically functional landscape design and
management practices; Additional detail regarding landscaping design is
discussed in section 7.2.
- Minimizing project's impervious footprint. Methods of accomplishing this goal
include constructing streets, sidewalks, and parking lots to the minimum
widths necessary without compromising public safety. Another method for
minimizing impervious area includes incorporating landscaped areas in the
drainage system to encourage infiltration and reduce the amount of directly
connected impervious areas.
DE:DE h:\swqualityi2352\92nOoe23824\swmp-tm-05.cJoc
w.o. 2352-92 3/23/2005 1:33 PM
VIII
La Costa Ridge - Neighborhoods 2.3 & 2.4
Storm Water Management Plan
CHAPTER 8 - TREATMENT CONTROL BMP DESIGN
VORTECHS TREATMENT UNIT
8.1 - BMP Location
The proposed site design for the La Costa Ridge Neighborhood 2.3 & 2.4 project
includes a single Vortechs treatment unit (shown on the BMP Location Map located
at the end of this report). The Vortechs unit is located at the discharge location of
the storm drain within Corinthia Street, near the intersection of Corinithia Street and
El Fuerte Street in Neighborhood 2.3.
8.2 - Determination of Design Treatment Flow
The 85th percentile design flow rate has been calculated using the Rational Method.
Required data for the Rational Method treatment flow determination include the
following:
- Runoff Coefficient (C)
- Rainfall Intensity (I) = 0.20 inches per hour
Drainage area to treatment unit (A)
A Runoff coefficient was derived based upon a weighted average of each area
tributary to the treatment unit and the associated runoff coefficient.
The following table summarizes the parameters used for determination of design
flows the proposed flow-based treatment unit.
DESIGN RUNOFF DETERMINATION SUMMARY TABLE
Treatment Unit
Corinthia Street -
Neighborhood 2.3
Runoff
Coefficient
(C)
0.54*
85tn
Percentile
Rainfall
(inches/hour)
0.2
Drainage
Area
(acres)
42.6
85th Pet.
Design Flow
(cfs)
4.56
*= weighted C coefficient
8.3 - Vortechs Treatment Unit Selection
;thThe proposed Vortechs unit is an offline precast treatment unit. The 85 percentile
design flow rate will be forced into the treatment area by a diversion weir built in the
upstream junction. Flows in excess of the design flow rate pass over the weir and
proceed downstream. The calculations determining the peak flows being forced into
the treatment during a 100-year storm event will govern the sizing requirements
necessary to adequately treat the entire flow passing through the unit during this
significant rainfall event.
DE:DE h:\swquality\2352\92ndoe23J2.4\swinp-lm-05.doc
w.o. 2352-92 3/23/2005 1:33 PM
La Costa Ridge - Neighborhoods 2.3 & 2.4
Storm Water Management Plan
The following table shows the treatment capacity of the proposed Vortechs, or
approved equivalent unit.
VORTECHS UNIT TREATMENT CAPACITY TABLE
Treatment Unit
Corinthia Street -
Neighborhood 2.3
85tn Pet.
Design Flow
(cfs)
4.56
Recommended
Vortechs
Model
7000
Treatment Capacity
(cfs)
11.0
As it is evident above, the treatment capacity of the Vortechs Model 7000 is greater
than the treatment flow provided from the 85th percentile flow (see attached Vortech
unit sizing data). As such, a Vortechs Model 7000 has been selected to treat storm
water runoff from the proposed La Costa Ridge Neighborhoods 2.3 & 2.4
development.
OE:DE h:\swquallty\235M2rtdoe 2.3 i2.4\swmp.tm-05.doc
w.o. 2352-92 3/23/2005 1:34 PM
85TH PERCENTILE PEAK FLOW AND VOLUME DETERMINATION
Modified Rational Method - Effective for Watersheds < 1.0 mi2
Hunsaker & Associates - San Diego
Note: Only Enter Values in Boxes - Spreadsheet Will Calculate Remaining Values
Project Name La Costa Ridge Neighborhood 2.3 & 2.4 |
Work Order
Jurisdiction
2352-92 |
City of Carlsbad ]
BMP Location [BMP #1 Corinthia Street
85th Percentile Rainfall••
(from County Isopluvial Map)
Developed Drainage Area =
Natural Drainage Area =
| 0.68 [inches
Dev. Area Runoff Coefficient =
Nat. Area Runoff Coefficient =
Runoff Coefficient =
acres
acres
Total Drainage Area to BMP = 42.6 acres
Time of Concentration = | 9.8 | minutes
(from Drainage Study)
RATIONAL METHOD RESULTS
Q = CIA where
V = CPA where
Q = 85th Percentile Peak Flow (cfs)
C = Runoff Coefficient
I = Rainfall Intensity (0.2 inch/hour per RWQCB mandate)
A = Drainage Area (acres)
Q = 85th Percentile Runoff Volume (acre-feet)
C = Runoff Coefficient
P = 85th Percentile Rainfall (inches)
A = Drainage Area (acres
Using the Total Drainage Area:
C= 0.54
I = 0.2 inch/hour
P = 0.68 inches
A = 42.6 acres
Q =
V =
Using Developed Area Only:
4.56 cfs
1.29 acre-feet
c =
p =
A =
Q =
V =
0.55
0.2 inch/hour
0.68 inches
39.5 acres
4.35 cfs
1.23 acre-feet
Vortechs ™ Stormwater Treatment Systems
FLOW CALCULATIONS
\brtechnics® La Costa Rid9e 2-1 ~2-5
^gT Carlsbad, CA
^§? Model 7000
^ System BMP #1 @ Sta 1 3+65.02
Vortechs Orifice Vortechs Weir
Cd = 0.56 Cd = 3.33
A (ft2) = 1 .33 Weir Crest Length (ft) = 0
Crest Elevation (ft) = 534.1 8 Crest Elevation (ft) = 538.1 0
Bypass Weir
Cd = 3.3
Weir Crest Length (ft) = 6.4
Crest Elevation (ft) = 536.1
Head
(ft)
0.00
0.25
0.50
0.75
1.00
1.25
1.50
1.75
2.00
2.25
2.50
2.75
3.00
3.25
3.50
4.27
Elevation
(ft)
534.18
534.43
534.68
534.93
535.18
535.43
535.68
535.93
536.18
536.43
536.68
536.93
537.18
537.43
537.68
538.45
Orifice Flow
(cfs)
0.00
0.67
1.88
3.46
4.71
5.57
6.32
6.98
7.59
8.15
8.68
9.18
9.65
10.10
10.53
11.75
Weir Flow
(cfs)
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
Bypass Flow
(cfs)
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.51
4.06
9.40
16.06
23.80
32.50
42.06
76.25
Total Flow
(cfs)
0.00
0.67
1.88
3.46
4.71
5.57
6.32
6.98
8.10
12.21
18.08
25.23
33.45
42.60
52.59
88.00
Calculated by: WSG 10/7/2004 [(Checked by:
50)
Vortechs™ System
Stage Discharge Curve
10.0 20.0 30.0 40.0 50.0 60.0
Discharge (cfs)
70.0 80.0 90.0 100.0
6680ADSBMP #1 @ Sta 13+65.02.xls 3/23/2005
WATER QUALITY
TREATMENT BASIN
LEGEND
WATERSHED BOUNDARY
WATER QUALITY UNIT
PREPARED BY:
HUNSAKER
& ASSOCIATESIAN o tic a me
KVOUNG In Dhfo, b Km
MtvcvMc mto«si»«w-«(i
BMP LOCATION MAP FOR:
LA COSTA RIDGE
NEIGHBORHOODS 2.3 AND 2.4
CITY OF CARLSBAD, CALIFORNIA
SHEET
1
OF
1
2085JMar—22-2005i
La Costa Ridge
th percentlle - 0.68 Inches
— "i • iir 111 i -1 • IM iffl mi i i*mammmo r m w aT: e r
Treatment System
The Vortechs Storm water Treatment System, a major advancement
in oil and grit separator technology, efficiently removes grit, contami-
nated sediments, metals, hydrocarbons and floating contaminants
from surface runoff.
The Vortechs System's innovative design combines
swirl-concentrator and flow-control technologies to
optimize treatment efficiency. These features
ensure effective capture of sediment and oils, and
prevent resuspension of trapped pollutants - even
at flow rates of up to 25 cfs.
• Large system capacity provides an 80% net
annual TSS removal rate
• Installs below grade, minimizing land use
• Custom-built of precast concrete near the job site
• Low pump-out volume and one-point access
reduce maintenance costs
• Unique design prevents oils and other float-
ables from escaping the system during cleanout
Vortechs Systems may be
used in a wide range of
water-quality improvement
applications, including:
Wetlands/Waterfront
Protection
Retail
Development
Industrial Sites
Municipal Improvements
Commercial Development
Transportation Facilities
Existing Site Retrofits
"We have worked with
Vortechnics on at least a
dozen stormwater
management plans for
some of our largest
corporate clients. Their
efficient turnaround on
our requests for technical
support and CADD
drawings has expedited
the permitting process
for our clients. We turn
to Vortechnics when
we need innovative
stormwater solutions."
- Lawrence Marsiglio, RE.
Senior Civil Engineer,
Barakos-Landino, Inc.
Stormwater Treatment System
Perforated Covers
Plan View Elevation View
To begin the design of your
Vortechs System, refer to the
sizing chart below and com-
plete a Specifier's Worksheet to
provide details about your site
and design flows. Then simply
fax or mail the worksheet to
Vortechnics with your site plan,
and we'll produce detailed
Vortechs System scale draw-
ings free of charge.
— tlOOO *
j " 2000 -
' rt 3000
' 4000
. "'- 5000
; 7000
-,9000''
,; ,11000
V"'" 16000 ' '
3/7
4/13
5/20
6/28
7/38
8/50
9/64
10/79
12/113
1.6
2.8
4.5
6.0
8.5
11.0
14.0
17.5
25.0
.75
1.25
1.75
2.5
3.25
4.0
4.75
5.5
7.0
•9*3.;:;iB
10x4 -|
11x5, ,|
12x6' , 1
13 x^. ; 1
14x8 r|
15x9 -|
16x10 "1t ^H1 18x12 ='•
Engineering Notes
A] Far in-line Vortechs Systems without a bypass, sizing criteria is based on providing one square foot of grit
chamber surface area for each 100 gpm of peak design storm flow rate (e.g.. IQyear storm). For more
details about Vortechnics sizing criteria refer to Vortechnics Technical Bulletin 3.
B] Sediment storage volume assumes a 3 foot sump.
C] Construction details may very depending on the specific application. Any alterations to the sizing chart specifi-
cations will appear on Vortechnics dimensional and shop drawings. Please call Vortechnics for the weight of spe-
cific Vortechs systems if needed.
Special Note: Oil storage capacity, when it is needed to meet a specific requirement for spill containment, can be
sized to meet the storage requirement with the selected model. Vortechnics technical staff will optimize system
geometry to meet containment requirements within a correctly sized Vortechs System.
Metric Specification Chart available by celling Vortechnics at 12O7J B78-3662.
Vortechs System Inlet/Outlet Configurations
Vortechs Systems can be configured to accommo-
date various inlet and outlet pipe orientations.
The inlet pipe can enter the end or side of the
tank at right angles - outlet pipes can exit the end
or the side of system at most angles.
End Inlet Side Inlet
To
Polish
/
t
' )—
Pretreatment ^liL,
peratBon
Plan View
Grit Chamber Dil Chamber/ Flow Controlbnt Lhamber chamber
Elevation View: Dry-Weather
Grit Chamber
The swirling motion created by the
tangential inlet directs settleable
solids toward the center of this ^ -
chamber. Sediment is caught in.x>
the swirling flow path and settles
back onto the pile after the storm
event is over. T " ' c.-..'„"„ ^. .
Oil Chamber & Baffle Wall
The center baffle traps floatables in
the oil chamber, even during clean-
out. Highly resistant to flow surges.
Flow Control Chamber "..
The weir and orifice flow controls:
1) Raise level and volume in the
system as flow rate increases; and
2] gradually drain the system as
flow rate subsides.
1) Initial Wet Weather Phase
During a two-month storm event the water level begins to
rise above the top of the inlet pipe. This influent control
feature reduces turbulence and avoids resuspension
of pollutants.
3) Full Capacity Phase
When the high-flow outlet approaches full discharge, storm
drains are flowing at peak capacity. The Vortechs System is
designed to match your design storm flow and provide treat-
ment throughout the range of storm events without bypass-
ing. To accommodate very high flow rates, Vortechnics can
assist designers with configuring a peak-flow bypass.
2) Transition Phase
As the inflow rate increases above the controlled outflow
rate, the tank fills and the floating contaminant layer accu-
mulated from past storms rises. Swirling action increases
at this stage, while sediment pile remains stable.
4) Storm Subsidence Phase/Cleaning
Treated runoff is decanted at a controlled rate, restoring the
water level to a low dry-weather volume and revealing a conical
pile of sediment. The low water level facilitates inspection and
cleaning, and significantly reduces maintenance costs. The
system's central baffle prevents transfer of floatables to the
outlet during cleaning or during the next storm.
SECTION 02721
STORMWATER TREATMENT SYSTEM
PART 1.00 GENERAL
1.01 DESCRIPTION
A. Work included:
The Contractor, and/or a manufacturer selected by the Contractor and approved
by the Engineer, shall furnish all labor, materials, equipment and incidentals
required and install all precast concrete stormwater treatment systems and
appurtenances in accordance with the Drawings and these specifications.
B. Related work described elsewhere:
1. Unit Masonry
2. Miscellaneous Metals
3. Waterproofing
1.02 QUALITY CONTROL INSPECTION
A. The quality of materials, the process of manufacture, and the finished sections
shall be subject to inspection by the Engineer. Such inspection may be made at
the place of manufacture, or on the work site after delivery, or at both places, and
the sections shall be subject to rejection at any time if material conditions fail to
meet any of the specification requirements, even though sample sections may
have been accepted as satisfactory at the place of manufacture. Sections
rejected after delivery to the site shall be marked for identification and shall be
removed from the site at once. All sections which have been damaged beyond
repair during delivery will be rejected and, if already installed, shall be repaired to
the Engineer's acceptance level, if permitted, or removed and replaced, entirely
at the Contractor's expense.
B. All sections shall be inspected for general appearance, dimensions, soundness,
etc. The surface shall be dense, close textured and free of blisters, cracks,
roughness and exposure of reinforcement.
C. Imperfections may be repaired, subject to the acceptance of the Engineer, after
demonstration by the manufacturer that strong and permanent repairs result.
Repairs shall be carefully inspected before final acceptance. Cement mortar
used for repairs shall have a minimum compressive strength of 4,000 psi at the
end of 7 days and 5,000 psi at the end of 28 days when tested in 3 inch diameter
by 6 inch long cylinders stored in the standard manner. Epoxy mortar may be
utilized for repairs.
1.03 SUBMITTALS
A. Shop Drawings
The Contractor shall be provided with dimensional drawings and, when specified,
utilize these drawings as the basis for preparation of shop drawings showing
details for construction, reinforcing, joints and any cast-in-place appurtenances.
Shop drawings shall be annotated to indicate all materials to be used and all
applicable standards for materials, required tests of materials and design
assumptions for structural analysis. Design calculations and shop drawings shall
be certified by a Professional Engineer retained by the system manufacturer or
contractor and licensed in the state where the system is to be installed. Shop
drawings shall be prepared at a scale of not less than 1/4" per foot. Six (6) hard
copies of said shop drawings shall be submitted to the Engineer for review and
approval.
B. Affidavit on patent infringement
The Contractor shall submit to the Engineer, prior to installation of the stormwater
treatment system, an affidavit regarding patent infringement rights stating that
any suit or claim against the Owner due to alleged infringement rights shall be
defended by the Contractor who will bear all the costs, expenses and attorney's
fees incurred thereof.
PART 2.00 PRODUCTS
2.01 MATERIALS AND DESIGN
A. Concrete for precast stormwater treatment systems shall conform to ASTM
C 857 and C 858 and meet the following additional requirements:
1. The wall thickness shall not be less than 6 inches or as shown on the
dimensional drawings. In all cases the wall thickness shall be no less than
the minimum thickness necessary to sustain HS20-44 loading requirements
as determined by a Licensed Professional Engineer.
2. Sections shall have tongue and groove or ship-lap joints with a butyl mastic
sealant conforming to ASTM C 990.
3. Cement shall be Type III Portland cement conforming to ASTM C 150.
4. Pipe openings shall be sized to accept pipes of the specified size(s) and
material(s), and shall be sealed by the Contractor with a hydraulic cement
conforming to ASTM C 595M
5. Internal metal components shall be aluminum alloy 5052-H32 in accordance
with ASTM B 209.
6. Brick or masonry used to build the manhole frame to grade shall conform to
ASTM C 32 or ASTM C 139 and the Masonry Section of these Specifications.
\\MDI\SYS\DATA\VORTECHN\EMAIL\STDETAIL\VORTSPEC.DOC SECTION 02721 Page 2
7. Casting for manhole frames and covers shall be in accordance with The
Miscellaneous Metals Section of these Specifications.
8. All sections shall be cured by an approved method. Sections shall not be
shipped until the concrete has attained a compressive strength of 4,000 psi or
util 5 days after fabrication and/or repair, whichever is the longer.
9. A butimen sealant in conformance with ASTM C 990 shall be utilized in
affixing the aluminum swirl chamber to the concrete vault.
2.02 PERFORMANCE
Each stormwater treatment system shall adhere to the following performance specifications
at the specified design flows, as listed below:
Table 2.02
Vortechs
Model
1000
2000
3000
4000
5000
7000
9000
11000
16000
Swirl
Chamber
Diameter
(ft)
3.67
4
5
6
7
8
9
10
12
Design
Treatment
Capacity
(cfs)
2.3
2.8
4.5
6.0
8.5
11.0
14.0
17.5
25.0
Sediment
Storage
(yd3)
1.00
1.25
1.75
2.50
3.25
4.00
4.75
5.50
7.00
Each stormwater treatment system shall include a circular aluminum "swirl chamber" (or "grit
chamber") with a tangential inlet to-induce a swirling-flow pattern that will accumulate and
store settleable solids in a manner and a location that will prevent re-suspension of previously
captured particulates. Each swirl chamber diameter shall not be less than the diameter listed
in Table 2.02 (neglecting chamber wall thickness).
Each stormwater treatment system shall be of a hydraulic design that includes flow controls
designed and certified by a professional engineer using accepted principles of fluid mechanics
that raise the water surface inside the tank to a pre-determined level in order to prevent the
re-entrainment of trapped floating contaminants.
Each stormwater treatment system shall be capable of removing 80% of the net annual Total
Suspended Solids (TSS). Individual stormwater treatment systems shall have the Design
Treatment Capacity listed in Table 2.02, and shall not resuspend trapped sediments or re-
entrain floating contaminants at flow rates up to and including the specified Design Treatment
Capacity.
Individual stormwater treatment systems shall have usable sediment storage capacity of not
less than the corresponding volume listed in Table 2.02. The systems shall be designed such
\\MDI\SYS\DATA\VORTECHN\EMAIL\STDETAIL\VORTSPEC.DOC SECTION 02721 PageS
„ that the pump-out volume is less than 1/z of the total system volume. The systems shall be
designed to not allow surcharge of the upstream piping network during dry weather conditions.m
A water-lock feature shall be incorporated into the design of the stormwater treatment system
to prevent the introduction of trapped oil and floatable contaminants to the downstream piping
* during routine maintenance and to ensure that no oil escapes the system during the ensuing
rain event. Direct access shall be provided to the sediment and floatable contaminant storage
"* chambers to facilitate maintenance. There shall be no appurtenances or restrictions within
« these chambers.
» The stormwater treatment system manufacturer shall furnish documentation which supports
ai all product performance claims and features, storage capacities and maintenance
requirements.
•m
M Stormwater treatment systems shall be completely housed within one rectangular structure.
2.03 MANUFACTURER
*Each stormwater treatment system shall be of a type that has been installed and used
successfully for a minimum of 5 years. The manufacturer of said system shall have
* been regularly engaged in the engineering design and production of systems for the
physical treatment of stormwater runoff.
•*»
TM<• Each stormwater treatment system shall be a Vortechs System as manufactured by
Vortechnics, Inc., 41 Evergreen Drive, Portland, Maine 04103, phone: 207-878-3662,
fax: 207-878-8507; and as protected under U.S. Patent # 5,759,415.
m
PART 3.00 EXECUTION
3.01 INSTALLATION
— • A. Each Stormwater Treatment System shall be constructed according to the sizesm shown on the Drawings and as specified herein. Install at elevations and
locations shown on the Drawings or as otherwise directed by the Engineer.
*""* B. Place the precast base unit on a granular subbase of minimum thickness of six
inches after compaction or of greater thickness and compaction if specified
elsewhere. The granular subbase shall be checked for level prior to setting and
m the precast base section of the trap shall be checked for level at all four corners
after it is set. .If the slope from any corner to any other comer exceeds 0.5% the
base section shall be removed and the granular subbase material re-leveled.
-*
C. Prior to setting subsequent sections place butimen sealant in conformance with ASTM
"*" C990-91 along the construction joint in the section that is already in place.
•m
D. After setting the base and wall or riser sections install the circular swirl chamber
•» wall by bolting the swirl chamber to the side walls at the three (3) tangent points
and at the 3-inch wide inlet tab using HILTI brand concrete anchors or equivalent
1/2-inch diameter by 2-3/4" minimum length at heights of approximately three
„ inches (3") off the floor and at the mid-height of the completed trap (at locations
of pre-drilled holes in aluminum components). Seal the bottom edge of the swirlj»
\\MDI\SYS\DATA\VORTECHN\EMAIL\STDETAILWORTSPEC.DOC SECTION 02721 Page 4
chamber to the trap floor with the supplied aluminum angle flange. Adhere %"
thick by 1" wide neoprene sponge material to the flange with half of it's width on
the horizontal leg of the flange and half of it's width on the vertical leg. The
aluminum angle flange shall be affixed to the floor with a minimum 3/8" diameter
by 2-3/4" drop in wedge anchor at the location of the predrilled holes. Affix the
swirl chamber to the flange with hex head %" x 1-1/2" zinc coated self- tapping
screws at the location of the predrilled holes. Seal the vault sidewalls to the
outside of the swirl chamber from the floor to the same height as the inlet pipe
invert using butyl mastic or approved equal.
E. Prior to setting the precast roof section, butimen sealant equal to ASTM C990 shall be
placed along the top of the baffle wall, using more than one layer of mastic if
necessary, to a thickness at least one inch (1") greater than the nominal gap between
the top of the baffle and the roof section.
The nominal gap shall be determined either by field measurement or the shop
drawings. After placement of the roof section has compressed the butyl mastic sealant
in the gap, finish sealing the gap with an approved non-shrink grout on both sides of
the gap using the butyl mastic as a backing material to which to apply the grout. Also
apply non-shrink grout to the joints at the side edges of the baffle wall.
F. After setting the precast roof section of the stormwater treatment system, set
precast concrete manhole riser sections, to the height required to bring the cast
iron manhole covers to grade, so that the sections are vertical and in true
alignment with a 1/4 inch maximum tolerance allowed. Backfill in a careful
manner, bringing the fill up in 6" lifts on all sides. If leaks appear, clean the inside
joints and caulk with lead wool to the satisfaction of the Engineer. Precast
sections shall be set in a manner that will result in a watertight joint. In all
instances, installation of Stormwater Treatment Systems shall conform to ASTM
specification C891 "Standard Practice For Installation of Underground Precast
Utility Structures".
G. Plug holes in the concrete sections made for handling or other purposes with a
nonshrink grout or by using grout in combination with concrete plugs.
H. Where holes must be cut in the precast sections to accommodate pipes, do all
cutting before setting the sections in place to prevent any subsequent jarring
which may loosen the mortar joints. The Contractor shall make all pipe
connections.
\\MDI\SYS\DATA\VORTECHN\EMAIL\STDETAIL\VORTSPEC.DOC SECTION 02721 Page 5
IX
La Costa Ridge - Neighborhoods 2.3 & 2.4
Storm Water Management Plan
Chapter 9 - FISCAL RESOURCES
9.1 - Fiscal Mechanism Selection
The table below illustrates the maintenance mechanism selection criteria and its
associated fiscal funding source. The shaded portion of the table highlights the
mechanism associated with the La Costa Ridge Neighborhoods 2.3 & 2.4 project.
»»»»»»» Increased risk, complexity, cost or other maintenance factors>»»»»»»»»
(Private Responsibility)
Importance of
Maintenance
Typical BMPs
Mechanisms
Funding
Source(s)
First Category
Minimal
concern;
inherent in
BMP or
property
stewardship
Biofilter (Grass
swale, grass
strip, vegetated
buffer);
Infiltration
basin/trench
Second Category
(Public Responsibility)
Third Category
Need to make sure ij Warrants Flood
private owners | Control Dist. (FCD)
i maintain, andli 1 assuming
provide County 1 responsibility, with
ability to step in & I funding related to
perform i project
maintenance
[First cat. plus:]
Minor wetland swale;
Small detention
basin; Single storm
drain insert /Oil-
water separator /
Catch basin insert &
screen
1 . Stormwater Ordinance requirement
[section 67.81 9(a)&(b)], with code
enforcement
2. Nuisance abatement with costs
charged back to property owner
3. Condition in ongoing permit such as
a Major Use Permit (if project has
MUP)
4. Notice to new purchasers
[67.819(e)3
5. Subdivision public report "white
papers" to include notice of
maintenance responsibility
None
necessary
6,:;; Recorded!*; :^..-:
easement
agreement
w/covenant
binding on
successors
Security (Cash
deposit, Letter of
Credit, or other
acceptable to County)
for interim period.
Agreement for
security to contain
provisions for release
or refund, if not used.
[Second cat. plus:]
Wetland swale or
bioretention;
Detention basin
(extended/dry); Wet
ponds & wetlands;
Multiple storm drain
inserts; Filtration
Systems
1. Dedication to FCD.
2. Formation of
benefit area
3. FCD maintenance
documentation
Start-up interim:
Developer fee
covering 24 months
of costs
Permanent:
FCD Assessment
per FCD Act Sec
105-17.5
Fourth Category
Broader public
responsibility for
maintenance and
funding (beyond
project)
[Third cat. plus:]
Retrofit public
storm drain
inserts, etc.
Master plan
facility
that serves area
larger than project
1 . Dedication to
FCD or
County.
2. FCD /County
maintenance
documentation
Varies: gas tax for
BMP in road
ROW, Transnet
for CIP projects,
Special funding or
General funding
for others.
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La Costa Ridge - Neighborhoods 2.3 & 2.4
Storm Water Management Plan
9.2 - Agreements (Mechanisms to Assure Maintenance)
There is a single flow based treatment unit and a single volume based treatment
basin on the La Costa Ridge Neighborhoods 2.3 & 2.4 project site for storm water
quality treatment. Storm water quality units and basins fall within maintenance
category two based on the County's Guidelines for the Stormwater Maintenance
Plan. The Home Owners Association will be responsible to perform the
maintenance activities and to ensure adequate funding. The maintenance
agreement(s) will be found with the Home Owners Association's secretary. Security
to fund "backup" maintenance which would be performed by the City in the event
that the HOA's maintenance is inadequate is required.
The County of San Diego Watershed Protection, Stormwater Management, and
Discharge Control Ordinance require ongoing maintenance of BMPs to ensure the
proper function and operation of theses BMPs. Costs for this maintenance will be
the responsibility of the Home Owners Association at the time of inception and by
the contractor during construction of the development.
Additionally, a BMP Maintenance Agreement with Easement and Covenant will be
entered into with the city which will function in three ways. This agreement will
commit the land to being used only for purposes of the BMP; The agreement will
include an agreement by the landowner to maintain the facilities in accordance with
the SMP (which would be passed on to future purchasers or successors of the
landowner as a covenant); This agreement will include an easement giving the City
the right to enter onto the land and any adjacent land needed for access to maintain
the BMPs.
The Developer must provide the City with Security to back up the maintenance
agreement which would remain in place for an interim period of five years. The
amount of the security shall equal the estimated cost of two years of maintenance
activities. The security can be a Cash Deposit, Letter of Credit or other form
acceptable to the City.
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La Costa Ridge - Neighborhoods 2.3 & 2.4
Storm Water Management Plan
CHAPTER 10 - REFERENCES
"Standard Urban Storm Water Mitigation Plan - Storm Water Standards", City of
Carlsbad, April 2003.
"City of Carlsbad Engineering Standards"; Volume 1 - General Design Standards;
Chapter 5 - Drainage and Storm Drain Standards; City of Carlsbad,
California; June 2004.
"Master Drainage and Storm Water Quality Management Plan", City of Carlsbad,
California; March 1994.
"Drainage Study for La Costa Ridge - Neighborhood 2.3 & 2.4", Hunsaker &
Associates San Diego, Inc.; March, 2005.
"Mass Graded Hydrology Study for Villages of La Costa - Neighborhoods 2.1
through 2.5", Hunsaker & Associates San Diego, Inc.; January, 2004.
"San Diego County Hydrology Manual", County of San Diego Department of Public
Works - Flood Control Section; June 2003.
"Order No. 2001-01, NPDES No. CAS0108758- Waste Discharge Requirements for
Discharges of Urban Runoff from the Municipal Separate Storm Sewer Systems
(MS4s) Draining the Watersheds of the County of San Diego, the Incorporated Cities
of San Diego County, and San Diego Unified Port District", California Regional
Water Quality Control Board - San Diego Region; February 21, 2001.
"Water Quality Plan for the San Diego Basin", California Regional Water Quality
Control Board - San Diego Region, September 8,1994.
"Vortechnics Storm Water Treatment System Manual", Vortechnics; Revised May
2000.
Drawing No. 397-3A "Grading and Erosion Control Plans for Villages of La Costa -
The Ridge"; Hunsaker & Associates San Diego, Inc; March 29, 2004.
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