HomeMy WebLinkAboutCT 04-02; LA COSTA RIDGE NEIGHBORHOODS 2.1 & 2.2; PRELIMINARY STORMWATER MANAGEMENT PLAN - SWMP; 2004-03-30I
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PLANNING
ENGINEERING
SURVEYING
IRVINE
LOS ANGELES
RIVERSIDE
SAN DIEGO
DAVE HAMMAR
LEX WILLIMAN
ALISA VIALPANDO
10179 Huennekens St.
San Diego, CA 92121
(858) 558-4500 PH
(858) 558-1414 FX
www.HunsakerSD.com
lnfo@HunsakerSD.com
HUNSAKER
&ASSOCIATES
S A N D I E G 0, I N C
PRELIMINARY STORM WATER
MANAGEMENT PLAN
for
LA COST A RIDGE
NEIGHBORHOODS 2.1 & 2.2
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. 2352-91
January 20, 2004
Amended March 30, 2004
Water Resources Department Manager
Hunsaker & Associates San Diego, Inc.
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PRELIMINARY STORM WATER
MANAGEMENT PLAN
for
LA COSTA RIDGE
NEIGHBORHOODS 2.1 & 2.2
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. 2352-91
January 20, 2004
Eric Mosolgo, R.C.E.
Water Resources Department Manager
Hunsaker & Associates San Diego, Inc.
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La Costa Ridge (Neighborhoods 2.1 & 2.2)
Preliminary 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
CHAPTER 2 -Storm Water Criteria
2.1 Regional Water Quality Control Board Criteria
2.2 City of Carlsbad SUSMP Criteria
CHAPTER 3 -Identification of Typical Pollutants
3.1 Anticipated Pollutants from Project Site
3.2 Sediment
3.3 Nutrients
3.4 Trash & Debris
3.5 Oxygen-Demanding Substances
3.6 Oil & Grease
CHAPTER 4 -Conditions of Concern
4.1 Receiving Watershed Descriptions
4.2 Pollutants of Concern in Receiving Watersheds
CHAPTER 5 -Flow-Based BMPs
5.1 Design Criteria
5.2 Vortechs Treatment Units
5.3 Pollutant Removal Efficiency Table
5.4 Maintenance Requirements
CHAPTER 6 -Volume-Based Best Management Practices (BMPs)
6.1 Design Criteria
6.2 Dual Purpose Detention and Water Quality Basin
6.3 Pollutant Removal
6.4 Maintenance Requirements
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La Costa Ridge (Neighborhoods 2.1 & 2.2)
Preliminary Storm Water Management Plan
CHAPTER 7 -Source Control BMPs
7.1 Landscaping
7.2 Urban Housekeeping
7.3 Automobile Use
7.4 Site Design
CHAPTER 8 -Site BMP Design (Vortechs Treatment Units)
8.1 BMP Locations
8.2 Determination of Treatment Flows
8.3 Vortechs Treatment Unit Selections
CHAPTER 9 -References
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 6 -Pollutant Removal Efficiency Table (Volume-Based BMPs)
Chapter 6 -Pollutant Removal Efficiency Table (Flow-Based BMPs)
Chapter 8 -85th Percentile Rainfall lsopluvial Map
Chapter 8 -Design Runoff Determination Spreadsheets
Chapter 8 -Low Flow Diversion Spreadsheet
Chapter 8 -Vortechs System Data
Attachment -Developed Site Map
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La Costa Ridge (Neighborhoods 2. 1 & 2.2)
Preliminary Storm Water Management Plan
CHAPTER 1 -EXECUTIVE SUMMARY
This report, "Preliminary Storm Water Management Plan for La Costa Ridge
Neighborhoods 2.1 and 2.2", specifically addresses treatment of 85th percentile
runoff from Neighborhoods 2.1 and 2.2. Runoff from Neighborhoods 2.1 and 2.2
drain to one of the two storm water quality treatment units located at the downstream
end of the perspective storm drain system (see Developed Site Map at the end of
this report). Some lots located in the south west of Neighborhood 2.2 drain to a
water quality treatment basin, located west of the site.
85th percentile design runoff calculations are provided in Chapter 7 of this report.
Since all treatment facilities are proposed as flow-based BMP, modified rational
methods were used to determine the corresponding 85th percentile runoff volume
from Neighborhoods 2.1 and 2.2.
1.1 -Introduction
The La Costa Ridge Neighborhoods 2.1 and 2.2 proposed project site is located in •
the City of Carlsbad, roughly located as shown in the vicinity map on this page. The
propose project site is bound by Alga Road to the north, El Fuerte Street to the west,
and La Costa Ridge Neighborhoods 2.3 to the south and 2.5 to the southeast.
!
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p.ALOMAR ~--
VICINITY MAP
N.T.S.
F
!ARCOS
\ OJECT
TE
Per the City of Carlsbad SUSMP, the La Costa Ridge 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
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La Costa Ridge (Neighborhoods 2.1 & 2.2)
Preliminary Storm Water Management Plan
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 has been prepared to recommend the location of site Best Management
Practices (BMPs), the determination of the 85th percentile runoff flow tributary to
each individual treatment unit and the determination of storm water treatment unit
sizing; which in the case of Neighborhoods 2.1 and 2.2 include two water quality
treatment units and also a storm water quality basin (see Developed Site Map at end
of report and also 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).
Furthermore, this report discusses anticipated project pollutants, pollutants of
concern in the receiving watershed, recommended source control BMPs, and
methodology used for the design of flow-based.
1.2 -Summary of Pre-Developed Conditions
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 4.51).
1.3 -Summary of Proposed Development
Development of the La Costa Ridge site will include the construction of single-family
homes as well as the associated streets, sidewalks, landscaping and utilities. As
part of the development, storm water treatment units will be installed to meet water
quality objectives set for the project.
Two flow-based BMPs will be located at two of the site discharge locations within .
Neighborhoods 2.1 and 2.2. Additional flow from Neighborhood 2.2 will be treated
via the storm water quality basin for Neighborhood 2.3. The additional discharge is
treated in a treatment unit in Neighborhood 2.5 prior to discharging into an existing
channel. The 85th percentile runoff will be treated in the proposed Vortechs systems
prior to discharging into the receiving drainage system.
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La Costa Ridge (Neighborhoods 2.1 & 2.2)
Preliminary Storm Water Management Plan
1.4 -Results and Recommendations
Using the 85th percentile rainfall of 0.68 inches (see lsopluvial Map at the end of this
chapter) and assuming percent imperviousness in the contributing watershed,
modified rational method calculations predicted an 85th percentile runoff volumes
and peak flows for the storm drain systems being treated within Neighborhoods 2.1
and 2.2. The westerly system will be required to treat 1.87 cfs or a volume of 0.53
acre-feet; while the northerly system will be required to treat 1.02 cfs or a volume of
0.29 acre-feet.
Each of the proposed storm water treatment units will be offline pre-cast treatment
units. 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 2.3 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 2.3, 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.
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La Costa Ridge (Neighborhoods 2.1 & 2.2)
Preliminary 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 runqff 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 SUS MP, the La Costa Ridge 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 APPLICAB_ILITY CHECKLIST
Complete Sections 1 and· 2 of the following checklist to determine your project's
perrnan~nt and construction storm water best management practices requirements.
This form .must be completed and submitted with your permit application.
SectJon 1. Permanent Storm Water BMP Requirements: .
If any answers to Part A are answered "Yes,n your project is subject t9 the-"Priority
Project Permanent Storm Water BMP Requiremcants,• and "Standard Permanent Storm
Water BMP Requirenientsn in Section Ill, "Permanent Storm Water BMP Selection
Proceduren in. the Storm Water Stand_ards manual.
If all an$wers to Part A are "No,11 and any answers.to Part 8 are "Yes,n 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 w~ter requirements. . •
. .
Part A: Determine Prioritv Proiect Permanent Storm Water BMP Requirements.
Does the project meet the definition of one or more of th~ priority project Yes No cateaories?* ,
1. Detached residential develocment of 1 0 or more units ✓
2. Attached residential develocment of 1 0 or more units .\/
3. Commercial development areater than 100.000 souare feet ./
4. Automotive repair shoo V
5. Restaurant ✓
6. Steep hillside development areater than 5,000 sauare feet ✓-
7. Prolect discharainq to receivina waters within Environmentallv Sensitive Areas ./
8._ Parking lots greater than or equal to 5,000 ft' er with at least 15 parking spaces, and ..
cotentiallv excosed to urban runoff
9. Streets, roads, highways, and freeways which would create a new paved surface that ls ✓ 5,000 souare feet or areater --
• Refer to the definitions section in the Stom, Water Standards for expanded definitions of the priority
crolect cateaories.
Umited Exclusion: Trenching and resurfacing work associated with utility projects are not considered
priority projects. Parking lots, buildings and other structures associated with utility projects are
priority projects if one or more of the criteria in· Part A Is met. If all answers to Part A are "No•,
continue to Part B.
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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 oervious landscaoe areas and irriaation svstems?
3. Permanent structures within 100 feet of anv natural water bodv?
4. Trash storaae areas?
5. Liauid or solid material loadina and unloadina areas?
6. Vehicle or eciuioment fuelina, washina, 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 aradiml or around disturbance durina construction?
1 0. Anv new storm drains, or alteration to existing storm drains?
Yes
✓·
v'
✓
,/
*To find out if your project is required to obtain an individual General NPDES Permit for Storm Water
No
✓
✓
,,,,,.
✓
✓
✓
Discharges Associated with Industrial Activities, visit the State Water Resources Control Board web si_te
at www.swrcb.ca.aov/stormwtr/lndustrial.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, 11Construction 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? Yes No
1. Is the project subject to California's statewide General NPDES Permit for Storm Water ✓ Discharnes Associated Wi1h Construction Activities?
2. Does the project propose grading or soil disturbance? v'
3. Would storm water or urban runoff have the potential to contact any portion of the ./ ..
construction area, including washina and staaina areas?
4. Would the project use any construction materials that could negatively affect water ✓ quality if discharged from the s~e (such as, pain~. solvents, concrete, and
stucco)?
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Storm Water Standards
4/03/03
Part D: Determine Construction Site Priority
In accordance with the Municipal Permit, each construction site with construction storm
water BMP requirements must be designated with a priority: high medium or low.
This prioritization must be completed with this form, noted on the plans, and included in
the SWPPP or WPCP. Indicate the project's priority in one of the check boxes using the
crit~~~ below, and existing and surrounding conditions of the project, th~ 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.] •
. ' AJ • 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
0 BJ 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 {N_Ols) and SWPPPs are not required. ••
0 CJ Low Priority
1) Capital Projects where minimal to rio grading 01::curs, $Uch as signal light and
loop installations, street light installations, etc.
2) Permit projects in the public right-q-way where minimal to no grading occurs,
such as pedestric~n 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.
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La Costa Ridge (Neighborhoods 2.1 & 2.2)
Preliminary Storm Water Management Plan
CHAPTER 3 -IDENTIFICATION OF TYPICAL POLLUTANTS
3.1 -Anticipated PoUutants from Proiect Site
The following table details typical anticipated and potential pollutants generated by
various land use types. The La Costa Ridge 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.
General Pollutant Cate ories
Priority
Project
Categories
J!? C Q)
E =a
J!? C Q) :s >, (I) >-
Q) en ::s z
cu s Q) Q)
J: :!
Attached
Residential X X
Develo ment
Commercial
Development p<1> p<1>
>100,000 ff
Automotive
Repair X
Sho s
Restaurants
Hillside
Development X X
>5,000 ft2
Parking Lots p<1> p<1> X
Streets,
Highways & X
Freewa s
Retail Gas
Outlets
X = anticipated
P = potential
p<1l X
X
.c .!!? (I) ... cu ,Q ... Q) I-C
X
p<2J X
x<4J(sJ X
X
X
X
X
X
C) (I)
C G>
·-CJ C "C C G> C CU
C) cu 1n >-E .a >< G) ::s occn
p(1)
p(S)
X
X
p(1)
p{S)
(1) A potential pollutant if landscaping exists on-site.
G) (I) cu G) ... C)
~
0
p(2)
X
X
X
X
X
X
X
~
.!!! (I) ... G) s (I)
CJ ::s ~5
p
p(3)
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.
X
p(S)
X
p(1)
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La Costa Ridge (Neighborhoods 2.1 & 2.2)
Preliminary 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 2.1 & 2.2)
Preliminary 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 both Encinitas Creek and
San Marcos Creek as part of the Carlsbad Hydro logic Unit, San Marcos Hydrologic
Area, and the Batiquitos Hydrologic Subarea (basin number 4.51).
4.2 -Pollutants of Concern in Receiving Watersheds
Neither Encinitas Creek nor San Marcos Creek are 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 both waterways 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 3-2 from the "Water Quality Plan for the San Diego Basin" (included at the end
of this Chapter) lists water quality objectives for a variety of potential pollutants
required to sustain the beneficial uses of the San Marcos hydrologic area.
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•• .. ~o 5000
.S. ·: ~ •:.
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-.;..;;,~-1'·()
WATERSHED MAP FOR ~
LA COSTA RIDGE ~
DEVELOPMENT 1 ci
err< OF CARLSBAD, CALIFORNJA 3:
lb\04:16"Hyd\04:lliSH03•VAT£RSH£D ElC.d•;l 2D3D]D1c•l7-2CD307oe2
'
Table 4-Combined 1998A and Draft 2002 ~ection 303(d} Update
Hydro logic Waterbody Segment/ Area 8 Pollutant/ Extent of Year
Oescrietor Strasser lmgalrment c Listed I 21 Loma Alta HA Pacific Ocean Shoreline at Loma Alta Creek Mouth Bacterial 1 mile (904.10) lndicatorse 1998
22 Loma Alta HA Loma Alta Slough Bacterial 8 acres i (904.10) lndicators5 1998
Eutroehic
23 Buena Vista Creek at Buena Vista Creek Bacterial 0.65 miles 1998 I HA (904.20) Pacific Ocean Shoreline Carlsbad City Beach at Carlsbad • lndicatorse Village Drive
Carlsbad State Beach at Pine
I Avenue
24 El Saito HSA et.iena Vista Lagoon Bacterial 350 acres 1998 (904.21) lndicatorse
I S~di':1entation / 350 acres 1998 Siltatron
Nutrients 150 acres 1998
1· 25 Los Monos HSA Agua Hedionda Lagoon Bacterial 5 acres 1998 (904.31) lndicators5 .
Sedimentation /
I Siltation
26 Los Monos HSA lower portion Diazinon lower2miles 2002
(904.31) Agu~ Hedionda Creek Tot~I Dissolved lower 8 miles 2002 Solids
I 21 San Marcos HA Pacific Ocean Shoreline at Moonlight State Beach Bacterial 0.4 miles 1998 (904.50) lndicatorse
28 Escondido Creek Pacific Ocean Shoreline at San Elijo Lagoon Bacterial 0.8 miles 1998
I HA !904.60) at Solana Beach lndicatorse
29 San Elijo HSA San Elijo Lagoon Bacterial 150 acres 1998 • (904.61) lndicators5
I Eutroehic 330 acres
S~di':1entation I 150 acres
Srltatron
I 30 San Dieguito HU at San Dieguito Lagoon Mouth Bacterial 0.8 miles 1998
(905.00) Pacific Ocean Shoreline Torrey Pines State Beach at Del lndicators5
Mar {Anderson Can:t;onl
I 31 Del Dies HSA Green Valley Creek Sulfate 1 mile 2002 (905.21)
32 Del Dies HSA Color Entire 2002
(905.21) Hodges Reservoir Entire Reservoir Nitrogen Reservoir·· 1· Phosehorus
Total Dissolved
Solids
I 33 Felicita HSA Felicita Creek Tot~I Dissolved lower 2.miles 2002 • !905.23} Solids
34 Felicita HSA Kit Carson Creek . Total Dissolved 1 mile· 2002
I !905.23l Solids
35 Highland HSA Phosehorus 1 mile 2002
(905.31) Cloverdale Creek Total Dissolved
I Solids
36 Sutherland HSA Entire Reservoir Color Entire 2002 (905.53) Sutherland Reservoir Reservoir
' last updated 12/17/2003
'
S:\WQS\303dllst1SO Slatf Report-20021.2002 draft 303d llst\ 38 Tabla 4. Combined 1998 and 2002 Updata.:ds\Table 4
11iiila 1tiiii 1tiiil .. 'till 1111 1111 1111 MIi -llllf ... .. ... lllr lllr
Table 2-2. BENEFICIAL USES 6-F. INLAND SURFACE WATERS
.. BENEFICIAL USE
1,2 M A I p G F p R R B w C w.
Hydrologlc Unit u G N R W· ·R 0 E E I A 0 I Inland Surface Waters Basin Number N R D -·o R s w C C ·o R L L . C H 1 2 L M D D
. -Saar Diego County Coastal Streams -continued .. Buena Vista Lagoon 4.21 See Coastal Waters-Tabie 2-3
Buena Vista Creek 4.22 + • • • • • ••
Buena Vista Creek 4.21 + • • • • • •
Agua Hedlonda 4.31 See Coastal Waters• Table 2-3
Agua Hedionda Cre~k 4;32 • • • •· • • •
Buena Creek 4:32 • • • • • • • ----Agua Hedionda· Creek 4.31 • • • • • •• •
Letterbox canyon 4;31 • • • • • • •
Canyon de las Encinas • 4'.40 + 0 • • •
San Marcos Creek Watershed
Batlquitos Lagoon 4.51 See Coastal Waters-Table 2-3
San Marcos Creek 4.52 + • ·• • • •
unnamed Intermittent streams • 4.53 + • • • • •
San Marcos Creek Wat~rshed
San Marcos Creek 4.51 + • • • • •
·Encinitas Creek 4.51 + • • • • •
1 Waterbodiea are Usted multiple times if they cross hydrologlc area or sub area boundaries. • Existing Beneficial Use
O Potential Be~eflclal Use 2 ~eneficial use designations apply to all tributaries to the Indicated waterbody, If not listed separately.
+ Excepted From MUN (See Text) ,
Tabl11 2-2·
BENEFICIAL USES 2-27
R s
A .P
R w
E N
•
March 12, 1997
Table 3-3. WATER QUALITY OBJECTIVES
Concentrations not to be exceeded more than 10% of the time during any one year period.
Constituent (mg/L or as noted)
Ground Water Hydrol()gic Turb Color Basin Unit TDS Cl S04 .%Na NOa Fe Mn MBAS a ODOR NTU Units F
Number
Buena Vista Creek HA 4.20
El Saito HSA a 4.21 3500 800 500 60 46 ,0.3 0.05 0.6 2.0 none 5 15 1.0
Vista HSA a 4.22 1000 b 400 b 500 b 60 10 b 0.3 b 0.05 b 0.5 0.76 b none 6 15 1.0
Agua Hedionda HA a 4.30 1200 500 500 60 10 0.3 0.05 0.5 0,75 none 5 16 1.0
Los Monos HSA aj 4.31 3600 800 500 60 46 0.3 0.05 0.6 2.0 norie 6 16 1.0
Encinas· HA a 4.40 3600 b 800 b 600 b 60 46 b 0.3 b 0,05 b • 0.5 2.0 b none 6 15 1.0
San Marcos • HA 88 4.60 1000 400 500 -60 10 0.3 0.06 0.o 0.75 none 6 16 1.0
Batiqultos .. HSA aek 4.51 3500 800 500 60 45 0.3 0.05 0.6 2.0 none 6 16 1.0
Escondido Creek HA a 4,60 750. 300 -300 60 1,0 0.3 0.05 0,5 0.76 none 5 15 1.0
San Elijo HSA B 4:,61 2800 700 600 60 45 0.3 0.05 0.5 1.0 .none 6 16 1.0
Escondido HSA 4.62 1000 300 400 60 10 0,3 0.06. 0.5 0.75 none 5 15 1.0
SAN DIEGUITO HVDROLOGIC UNIT 906.00
Solana Beach .. HA a 5.10 1500 .b 500 b .500 b 60 45 b o.a5 b 0.15 b 0.5 0.75 b none 5 16 1.0
Hodges HA 6.20 1000 b 400 b 600 b 60 10 b 0.3 b 0.06 b 0.6 0.75 b none 6 15 1.9'·
San Pasqual HA 6.30 1000 b 400 b 500 b 60 10 b 0.3 b 0.05 b 0.5 0.75 b none 6 16 • 1.0
Santa Marla Valley HA 5.40 1000 400 500 60 10 0.3 0.05 0.5 0.75 none 5 15 1.0
Santa Ysabel HA 5.50 600 250 250 60 5 0.3 0.05 0.5 0.76 none 6 15 1.0
PENASQUITOS HVDROLOGIC UNIT 906.00
Miramar Reservoir HA af 6.10 1200 500 500 60 10 .0.3 0.05 0.5 0.76 none 5 15 1.0
Poway· HA 6.20 750 q 300 300 60 10 0,3 0.05 0.5 0.75 none 5 15 1.0
Scripps HA 6.30 -------------
Miramar HA g 6.40 760 300 300 60 10 0.3 0.05 0.5 0.75 none 5 15 1.0
Tecolote HA 6.50 ----. --------
HA • Hydrologlo Area
HSA -Hydrologlc Sub Area (Lower case letter, Indicate endnotes following tho table,)
Tabla 3·3
WATER QUALITY OBJECTIVES Paga 3-29 October 13. 1994
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La Costa Ridge (Neighborhoods 2.1 & 2.2)
Preliminary Storm Water Management Plan
CHAPTER 5 -FLOW-BASED BMPS
5.1 -Design Criteria
Flow-based BMPs shall be designed to mitigate the maximum flowrate of runoff
produced from a rainfall intensity of 0.2 inch per hour. Such basins utilize either
mechanical devices (such as vaults that produce vortex effects) or non-mechanical
devices (based on weir hydraulics and specially designed filters) to promote settling
and removal of pollutants from the runoff.
Per the request of the City of Carlsbad, 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 2.1 & 2.2)
Preliminary 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
H
Trash & Debris
Ox en Demandin 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
(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 (1993), National Stormwater Best Management Practices Database (2001),
and Guide for BMP Selection in Urban Developed Areas (2001 ).
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La Costa Ridge (Neighborhoods 2.1 & 2.2)
Preliminary 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 he~vily on site activities than the size of the unit.
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La Costa Ridge (Neighborhoods 2.1 & 2.2)
Preliminary 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 2.3, 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 contains two dual purpose detention and water quality
basins -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.
Such runoff will be detained in the basin and will slowly dewater via the slots in the
side of the 24-inch riser. After passing through the riser, 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-
Nutrients -
Heavy Metals -
Trash & Debris -
Oxygen-Demanding Substances -
Oil & Grease -
High removal efficiency
Medium removal efficiency
Medium removal efficiency
High removal efficiency
Medium removal efficiency
Medium removal efficiency
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La Costa Ridge (Neighborhoods 2.1 & 2.2)
Preliminary 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 of the dual purpose detention and water quality basin will be the
responsibility of the Homeowners Association until the time at which the City of
Carlsbad assumes maintenance responsibilities. 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.
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----
. ' .
----
Storm Water Standards
4/03/03
Table 4. Structural Treatment Control BMP Selection Matrix.
Pollutant of Concern • Treatment Control BMP Categories
Blofilters Detention Infiltration Wet Ponds or Drainage Filtration
Basins Basins(1) Wetlands Inserts
Sediment M H H H L H
Nutrients L M M M L M
HeawMetals M M M H L H
Oraanlc Compounds u u u u L M
Trash & Debris L H u u M H
Oxygen Demanding L M M M L .M Substances •
• Bacteria u u H u. L . M
Oil &Grease M M u u L H
Pesticides u u u u L u
(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
Hydrodynamic
Separator Svstems'2>
M
L
.L
L
M
L
L
L
L
Sources: Guidance Specifying Management Measures for Sources of Nonpolnt Pollution In Coastal Wal!JIB (1993), National
_§f.o.rmwater Best Management Practlcas Database (2001), and Guide for BMP SelecUon In Urban Developed Areas {2001) .
.-~;~~{:~.;~:. ::{.,·-.:-·~ :•. :-.;.:_\ _:-........ ~ ' ... · .: .. .
.
..•.
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La Costa Ridge (Neighborhoods 2.1 & 2.2)
Preliminary 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 should be educated as to the proper
routine maintenance to landscaped areas including trimming, pruning, weeding,
mowing, replacement or substitution of vegetation in ornamental and required
landscapes.
Per the RWQCB Order, the following landscaping activities are deemed unlawful
and are thus prohibited:
Discharges of sediment
Discharges of pet waste
Discharges of vegetative clippings
Discharges of other landscaping or construction-related wastes.
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
should be educated as to the proper application of fertilizers and herbicides to lawns
and gardens.
The average household contains a wide variety of toxins such as oil/grease,
antifreeze, paint, household cleaners and solvents. Homeowners should be
educated as to the proper use, storage, and disposal 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 2.1 & 2.2)
Preliminary 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 should 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 should make all homeowners aware of the
aforementioned RWQCB regulations through a homeowners' education program. A
monitoring program should also be implemented to insure compliance.
7 .4 -Site Design BMPs
Priority projects, such as the La Costa Ridge 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.
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La Costa Ridge (Neighborhoods 2.1 & 2.2)
Preliminary Storm Water Management Plan
CHAPTER 8 -SITE BMP DESIGN
VORTECHS TREATMENT UNITS
8.1 -BMP Locations
The proposed site design for the La Costa Ridge Neighborhoods 2.1 and 2.2 project
includes two Vortechs treatment units (shown on Developed Site Maps located at
the end of this report).
One located in the westerly storm drain system, prior to discharging
into an existing channel, near the westerly boundary between
Neighborhood 2.1 and 2.2.
One located in the northerly storm drain system prior to discharging
into an existing channel to the east of Street 'B' near the intersection
with Alga Road.
8.2 -Determination of Design Treatment Flows
The 85th percentile design flow rates have been calculated using the Modified
Rational Method. Required data for the Rational Method treatment flow
determination include the following:
Runoff Coefficient (C)
Rainfall Intensity (I) = inches per hour
Drainage area to treatment unit (A)
Runoff coefficients were derived based upon a weighted average of each area
tributary to the treatment unit and the associated runoff coefficient. The output
spreadsheets detailing the treatment volume and peak flow for both treatment units
are included on the following pages.
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La Costa Ridge (Neighborhoods 2.1 & 2.2)
Preliminary Storm Water Management Plan
8.3 -Vortechs Treatment Unit Selection
In the proposed design, each of the proposed Vortechs units is an offiine precast
treatment unit. The 85th 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.
The weir in the by-pass structure will not only divert the 85th percentile flows, but a
greater flow during significant rainfall events. This report will size the treatment units
to treat all storm water flows that are forced into the treatment unit based on the
output from the spreadsheets titled Hydraulic Analysis of Low Flow Diversion &
Vortechs Unit (included on the following pages) determines the storm water flows
treated in the two proposed Vortechs units during the 100-year storm event. In
summary, BMP #1 serving the westerly storm drain system will need to treat 2.72 cfs
and BMP #2 serving the northerly storm drain system will need to treat 1.53 cfs.
Therefore the proposed BMP #1 will be a Vortechs Model 3000 and BMP #2 will be
a Vortechs Model 2000.
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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 2.1 & 2.2
Work Order 2352-91 I
Jurisdiction City of Carlsbad I
BMP Location IBMP #1 -Westerly system
85th Percentile Rainfall =
(from County lsopluvial Map)
Developed Drainage Area =
Natural Drainage Area =
Total Drainage Area to BMP =
Dev. Area Percent Impervious =
Overall Percent Impervious =
Dev. Area Runoff Coefficient =
Nat. Area Runoff Coefficient =
Runoff Coefficient =
Time of Concentration =
(from Drainage Study)
RATIONAL METHOD RESULTS
Q= CIA where
V= CPA where
Q=
C=
I=
A=
Q=
C=
P=
A=
Using the Total Drainage Area:
C=
I=
P=
A=
Q=
V=
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0.68 linches
18.1 acres
1.1 acres
19.2 acres
40 1%
38 %
0.55
0.35
0.54
8.0 lminutes
85th Percentile Peak Flow (cfs)
Runoff Coefficient
Rainfall Intensity (0.2 inch/hour per RWQCB mandate)
Drainage Area (acres)
85th Percentile Runoff Volume (acre-feet)
Runoff Coefficient
85th Percentile Rainfall {inches)
Drainage Area ( acres ~
0.54 \
0.2 inch/hour
0.68 inches
19.2 acres
2.07 cfs
0.59 acre-feet
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85TH PERCENTILE PEAK FLOW AND VOLUME DETERMINATION
Modified Rational Method -Effective for Watersheds < 1.0 tni2
Hunsaker & Associates -San Diego
Note: Only Enter Values in Boxes -Spreadsheet WIii Calculate Remaining Values
Project Name
Work Order
La Costa Ridge Neighborhood 2.1 & 2.2
2352-91 I
Jurisdiction City of Carlsbad I
BMP Location IBMP #2 -Northern system
85th Percentile Rainfall =
(from County lsopluvial Map)
Developed Drainage Area =
Natural Drainage Area =
Total Drainage Area to BMP =
Dev. Area Percent Impervious =
Overall Percent Impervious =
Dev. Area Runoff Coefficient =
Nat Area Runoff Coefficient =
Runoff Coefficient =
Time of Concentration =
(from Drainage Study)
RATIONAL METHOD RESULTS
Q=CIA where
V= CPA where
Q=
C=
I=
A=
a=:
C=
P=
A=
Using the Total Drainage Area:
C=
I=
P=
A=
Q=
V=
I 0.68 linches
7.6 acres
2.6 acres
10.2 acres •
40 1%
30 %
0.55
0.35
0.50
4.8 fminutes
85th Percentile Peak Flow (cfs}
Runoff Coefficient
Rainfall Intensity (0.2 inch/hour per RWQCB mandate)
Drainage Area (acres) •• •
85th Percentile Runoff Volume (acre-feet)
Runoff Coefficient
85th Percentile Rainfall (inches)
Drainage Area (acres •
0.50 \
0.2 inch/hour
0.68 ·inches
10.2 acres
1.02 cfs
0.29 acre-feet
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1) Initial Wet Weather Phase
During a two-f'Donth 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 cutlet approaches full discharge, storm
drains are ilciwng at peak capacity. The Vort.echs System is
designed t.a match your design storm flow and provide treat
ment throughout the range of storm events without bypass
ing. Ta accommodate very high flow rates, Vartechnics can
assist. designers with canfiaurinn A n~Ak-flnw h\/n:=,c:,c:,
2) Transition Phase
As the inflow rate increases above the controlled outflow
rate, the tank fills and the floar.ing contaminant layer accu
mulated from past· storms rise_s. Swirling action increases
at this stage, ~hile sediment pile remain_s stable.
4} Storm Subsidence Phase/Cleaning
Tr~ated 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 watef level facilit.ates inspection and
cleaning, and significantly reduces maintenance costs. The
system's central baffle prevents transfer af floatables to the
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Stormwater Treatment ystem
i----0 Plus 6' Typical-----..
Plan View
To begin the design of your
Vortechs System, refer to the
sizing chart below and com
-plete a Specifier's Worksheet to
provide· details about your site
·and design flows. Then simply
fax or mail the worksheet to
Vortechnics with your site plan,
and we'll produce detailed
Vortechs System scale draw
ings free 9£ charge.
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.
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3'm5'
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3'b:14'
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Perforated Covers
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8evation View
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End Inlet t
t
Side Inlet
-
To
Polish -
Ta Pretreatment outfall
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,, . .: .. PART 1.00 GENERAL
SECTION 02721
STORMWATERTREATMENTSYSTEM
1 ·'. 1.01 DESCRIPTION
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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.
B.
C.
The quality of materials, tile 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 rnay
have been accepted as satisfactory at the place of manµfacture. Sections
rejected after delivery to the site shall be marked for identification and shall be
removed from the site at once. All s~ctions 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 repla.ced_; entirely
at the Contractor's expense.
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 • '
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.
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1.03 SUBMITTALS
A. Shop Drawings
B.
The Contractor ~hall 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 li~ensed in the state where the system is to be installed. Shop
drawings shall be prepared at a seal~ of not less than 1/4" per foot. Six (6) hard
o;,pies of said shop drawings shall be submitted to the Engineer for review and
approval.
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. •
PART2.00 PRODUCTS
2.01 MATERIALS AND DESIGN
A Concrete for precast storrnwater 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 th~n
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 Ill Portland cement conforming to ASTM C 150.
· 4. Pipe openings shall be sized to accept pipes of the sp~cified size(s)·and
materiaJ(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 S052-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.
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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 ~fter 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
Swirl Design Sediment Vortechs Chamber Treatment
Model ·Diameter Capacity Storage
(ft) {cfs) (yd3)
1000 3.67 2.3 1.00
2000 4 2.8 1.25
3000 5 4.5 1.75
4000 6 6.0 2.50
5000 7 8.5 3.25
70.00 8 11.0 4.00
.9000 .9 • 14.0 4.75'
11000 10 17.5 5.50
16000 12 25.0 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 ac~umulate 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 thickries~).
Each stormwater treatment system shall be of a hydraulic design that indudes 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 t:apable 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
\\M)Jl\SYS\DATA\VORTECHN\EMAIL\STDETAIL\VORTSPEC.DOC SECTION 02721 Page3
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that the pump-out volume is less than ½ of the total system volume. The systems shall be
designed to not allow surcharge of the upstream piping network during dry weather conditions.
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
all product performance claims and features, storage capacities and maintenance
requirements.
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, Po~and, Maine 04103, phone: 207-878-3662,
fax: 207-878-8507; and as protected under U.S. Patent# 5,759,415.
PART 3.00 EXECUTION
3.01 INSTALLATION
A Each Stormwater Treatment System shall be constructed according to the sizes
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
the precasf base section of the trap shall be checked. for level at all four comers
after it is set. .If the slope from any comer to any other comer exceeds 0.5% the
base sedion 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.
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 HIL Tl 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 swirl
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chamber to the trap floor with the supplied aluminum angle flange. Adhere ¼"
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 ifs 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 ¼" 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 sh~II be determined either by field measurement or the shop
drawings. After placement of the roof section has compressed the butyl mastic sealant
in tne gap, finish sealing the gap with an approved non-shrink grout on both.sides of
the gap using the butyl !Tlastic 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 concret~ 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 ~omblnation with concrete plugs.
H. Where holes must be cut in the precast sections .to accommodate pipes, do all
cutting before setting the section~ in place to prevent any subsequent jarring
which may loosen the mortar joints. The Contractor shall make all pipe
connections.
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V ORTECHS™ ST0RMWATER TREATMENT S'fSTEM
DESIGN AND OPERATION
Basic Operation
The Vortechs System is sized on the basis of removing both sediment and floating pollutants
from stormwater runoff. When the system is operating at its peak design capacity, the
maximum service rate will be approximately 100 gallons-per-minute per square foot of grit
chamber area (gpm/sf). The Vortechs System has been tested for flows up to and Including
this maximum rate and has been shown to produce positive removal efficiencies throughout this
range.
The Vortechs System wi~I provid~ a net annual removal efficiency In excess of 80% removal of
Total Suspended So!ids as .they are typically encountered in runoff from urban environments.
The Vortechs System will also effectively capture and contain floatables in stormwater runoff.
The tangential inlet 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. Floatables entrapment is achieved by sizing the low flow
control to create a rise in the water level in the tank that is sufficient to just submerge the inlet
pipe In the 2-month storm.
The Vortechs System is designed to create a backwater condition within the system in· order to
maximize removal efficiencies. The amount of backwater varies and is determined by the
Vortechnics staff. To prevent flooding, the final design of the system incorporates all site
conditions.
Design Process
During the Vortechs System design process consideration is given to both the physical
constraints of..the site and the site-specific flows. Each system is designed differently based on
these characteristics, and the internal flow controls are specifically designed to accommodate
the expected flows.
The site engineer provides the Vortechs System rim and invert elevations, pipe sizes, design
flow rate, and design storm recurrence interval. Another consideration is whether the system is
in an on-line or off-line (i.e. bypassed) configuration. If regulatory authorities allow treatment of
storm flows less than the conveyance capacity of the piping system, It may be possible to
provide a Vortechs System in an off-line configuration which will result in a cost savings without
a significant reduction in pollutant removal efficiency.
Sizing the System • \
Each system is custom designed based cm the design conditions provideq. The weir, orifice,
sump depth, and height of tank will vary 'depending on the site conditions and performance
requirements. The rim and _invert elevations will impact the overall height of the unit, the sump
depth, and the placement of the weir and orifice. Also affecting the placement of the weir and
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V ORTECHS™ STORMWATER TREATMENT SYSTEM
orifice is the pipe size, the orientation of the internal walls, and the potential for tailwater. The ~
flow rates determine the size of the weir, orifice, and the baffle opening. 'ii
Size: The size of the system depends on whether or not the system is on-line or off-line. An
on-line system will be chosen such that the design flow rate is equal to or less then the
Vortechs rated design flow. For an off-line system, the 2-month flow rate is determined and 1t1e
model number is chosen based on the grit chamber area such that 24 gpm/sf of flow is realized
through the chamber.
V
• Sumo: Typically a three-foot sump depth is provided in Vortechs Systems. This depth is most
common since it provides ample sediment storage and keeps the excavation depth to a
minimum. However, because each Vortechs System is custom designed, the individual sump
depths m~y vary to balance maintenance costs with capital costs.
Orifice: The function of the qrifice is to . raise the water level in the Vortechs .system. This
increases the .ar.ea of the flow in the pipe, which decreases the velocity of the water flowing into
_the system. A reduction in turbulence is realized at the inlet; this aids in ~eeping the trapped
sediment and floatables contained. In additior.1, the rise in water level causes the floatables to
rise above the. inlet and away from the baffle opening, thus preventing the floatabies from
becoming re-entrained and pulled under the baffle wall. The orifice is designed to pass a flow
approximately equal to that of a 2-month storm event
I
Weir: Any event greater than the 2-month event causes the water level in the Vortechs System • 1
1
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to rise to the upper flow control, submerging the inlet. The upper flow control is normally a •
Clppoletti weir. A Cippoletti weir is a trapezoidal weir with 4 to 1 sloping sides. Like the orifice,
the weir also causes the water level in the system to rise, which promotes sediment and
floatable • removal. As the wat~r rises, the volume of water in the system increases, thus
stabilizing the detention time and allowing sediment to settle out. The swirl is maintained by
allowing continuous flow through the system via the weir and orifice. The weir is sized to pass
t_he design flow rate minus the orifice flow at full head.
Baffle: The baffle open'ing is designed to_ maintain a velocity such that re-entrainment of
flciatables and re-suspensi~n of sediment is minimized~ The baffle openin_g is at lea~t 6 inches
to ensure against clogging. The largest opening of 15 inches Is chosen to maximize the
distance between the floatable layer and the baffle opening. This keeps the floatables-trapped
_and maintains the oil storage volume. In most applications, the flow under the baffle wall is
approximately 1.0 foot per second. •
Bypass: For systems in an off-line configuration, a weir crest length and elevation is calculated
for the diversion structure that will be installed upstrear:n of the specified Vortechs System. The
goal is to achieve a water surface elevatior;i during· the 100-year storm that is at the same
elevation as the top of the Vortechs Cippoletti weir. The area of flow over· the bypass weir is
calculated based on the 100-year flow. From this area, the height of flow is solved for a given
weir length. Since the area of flow remains constant, the height of flow over the weir varies with
the bypass weir length. See Technical Bulletin 3A for more information.
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VORTECHS™ STORMWATER TREATMENT SYSTEM
Efaw Control Calculations Vortechs Model 5000
System
The Vortechs System W.Q.S. 1 is a Model 5000 with a 7.0-foot diameter grit chamber. In
this application, the runoff rate for a rainfall event with a return frequency of 1 O years is 6.13
cubic feet per second (cfs). The system design flow is 2751 gpm (6.13 cfs). The surface
area of the grit chamber is 38.5 square feet, therefore the peak operating rate is 27S1
divided by 38.5 or 7'?, gpm/sf.
The low flow control is a trapezoidal orifice (Q~riflce). Since the inlet is a 24-inch diameter
pipe, the orifice must raise the water level 24 inches, or 2.0 feet, in a 2-month storm to
submerge the inlet pipe. According to Vortechnics Technical Bulletin #3, _the 2-month storm
flow rate is approximately equal to the 10-year flow rate dMded by 7. The orifice calculation
based on the·full design flow is as follows: •
Q2-monlh =. Q10 year+ 7 = 6.13 + 7 = 0.88 cfs
Oor1t1ca = C(A)(2gh)0.s = _0.56(0.14)(2.0 x 32.2 x 2.0) o.s = 0.89 qfs 4
.
Where C = Orifice contraction coefficient= 0.56 (based on Vortechnics laboratory testing) .
A= Orifice flow area, ft2 (calculated by Vortechnics technical staff) •
h = Design head, ft (equal to the inlet pipe 'diameter)
A Cippoletti weir configuration is utilized as the high flow control (Owe1,) which is
conservatively designed for . the system design flow (Qde:fgn) of 6.13 cfs. The weir
calculations. are as follows:
Owi1r = 6.13 cfs ·
Owe1r = C(L)(H) u = 3;37(0.50)(2.42) 1.s = 6.34 cfs 4
Where C = Cippoletti Weir coefficient= 3.37 (based on Vortechr:iics laboratory testing)
H = Available head, ft (height of weir)
L = Design weir crest length, ft (calculated by Vortechnics technical staff)
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V O~TECHS™ STORMWATER TREATMENT SYSTEM
MAINTENANCE fj
The Vortechs System requires minimal routine maintenance. However, it is Important that the
system be inspected at regular intervals and cleaned when necessary to ensure optimum
performance. The rate at which the system collects pollutants will depend more heavily on site
a_ctivities than the size of the unit, e.g., heavy winter sanding will cause the grit chamber to fill
more quickly but regular sweeping will slow accumulation ..
Inspection
Inspection is the key -to effective maintenance . and it is easily performed. Vortechnics
recommends ongoing quarterly inspections of the accumulated sediment. Note that is not
unusual for sediment accumulation t~ be relatively light in the first year-as initial sediment loads
in new storm drainage systems may be diverted to catch basin sumps. Pollutant deposition and·
transport may vary from year to year and quarterly inspections will help insure that systems are
cleaned out at the appropriate time. Inspections should be performed more often in the winter
months in climates where sanding operations may lead .to rapid accumulations, or in equipment
washdown areas. It is very useful to keep a record of each inspection. A simple form for doing
so is provided. .
The Vortechs System only needs· to be cleaned when inspection reveals that it is nearly full;
specifically, when sediment depth has accumulated to within six inches of the dry-weather
water level. This determination can be made by taking 2 measurements with a stadia rod or •
similar measuring device:. one measurement is the distance from the manhole opening to the
top of the sediment pile and the other is the distance from the m~nhole opening to the water
surface.. If the difference between the two measurements is· less than six inches the system
should be deaned out Note: to avoid underestimating the volume of sediment fn the chamber,
the measuring device must be lowered to the top of the.'sediment pile carefully. Finer, silty
particles at the top of the pile typically offer less resistance to the end of the rod thaA larger
particles toward the bottom of the pile. •
In Vortechs installations where the risk of large petroleum spills is small, liquid contaminants
may not accumulate as quickly as sediment. However, an oil or gasoline spill should be
cleaned out immediately. Oil or gas that accumulates on a more routine basis should be •
removed when an appreciable layer has been captured. • '
Cleaning
Cleanout of the Vortechs System with a vacuum truck is generally the most .effective and
convenient method. Cleanout should not oc~ur within 6 hours of a rain event to ~llow the en~re
90llection system to drain down. Properly maintained Vortechs Systems will only require
evacuation of the grit chamber portion ·of the system, In which case only the manhole cover
nearest to the system inlet need be opened tq remove water and contaminants. However, all
chambers should be checked to ensure the integrity of the system. In installations where a
"cJamshell" is being utilized for solids removal, prior to removing the grit, absorbent pads or 1 pillows can be placed in the oil chamber to remove floating contaminants. Once this is done1
sediment may then be easily removed with the clamshell.
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V ORTECHS™ STORMWATER TREATMENT SYSTEM
In some cases, it may be necessary to pump out all chambers. An important maintenance
feature built into Vortechs Systems is that floatables remain trapped after a cleaning. A pocket
of water between the grit chamber and the outlet panel keeps the bottom of the baffle
submerged, so that all floatables remain trapped when the system begins to fill up again.
Therefore, in the event of cleaning other chambers it is imperative that the grit chamber be
drained first Manhole covers should be securely seated following cleaning activities, to ensure
that surface runoff does not leak into the unit from above.
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La Costa Ridge (Neighborhoods 2.1 & 2.2)
Preliminary Storm Water Management Plan
CHAPTER9-REFERENCES
"Standard Urban Storm Water Mitigation Plan -Storm Water Standards': City of
Carlsbad, April 2003.
"Standards for Design and Construction of Public Works Improvements in the City of
Carlsbad", City of Carlsbad, California; April 1993.
"Master Drainage and Storm Water Quality Management Plan", City of Carlsbad,
California; March 1994.
''Addendum to Preliminary Hydrology Study for Villages of La Costa -The Ridge and
The Oaks': Hunsaker & Associates San Diego, Inc.; Revised October 23, 2001.
"Hydrology Manual", County of San Diego Department of Public Works -Flood
Control Division; Updated April 1993.
"San Diego County Hydrology Manual': County of San Diego Department of Public
Works -Flood Control Section; June 2003.
"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.
"Mass Grading Hydrology Study for Villages of La Costa Neighborhoods 2. 1 through
2.5", Hunsaker & Associates San Diego, Inc., January, 2004 •
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