HomeMy WebLinkAboutCT 04-16; LA COSTA GREENS NEIGHBORHOOD 1.06; STORM WATER MANAGEMENT PLAN; 2005-01-20I
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STORM WATER
MANAGEMENT PLAN
for
LA COSTA GREENS
NEIGHBOR D 1 .. 6
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. 2352-106
January 20, 2005
Water Resources Department Manager
Hunsaker & Associates San Diego, Inc.
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La Costa Greens Neighborhood 1.6
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 & 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 Table
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 Greens Neighborhood 1.6
Storm Water Management Plan
CHAPTER 6 -Source Control BMPs
6.1 Landscaping
6.2 Urban Housekeeping
6.3 Automobile Use
6.4 Site Design BMPs
CHAPTER 7 -Treatment-Control BMP Design (Vortechs Treatment Unitr
7.1 BMP Location
7.2 Determination of Treatment Flows
7.3 Vortechs Treatment Unit Selections
CHAPTER 8 -References
List of Tables and Figures
Chapter 1 -Watershed Map
Chapter 3 -Pollutant Category Table
Chapter 4 -San Diego Region Hydrologic Divisions
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 (Flow-Based BMPs)
Chapter 7 -85th Percentile Rainfall Isopluvial Map
Chapter 7 -Neighborhood 1.6 BMP Location Map
Chapter 7 -Design Runoff Determination Summary Table
Chapter 7 -Vortechs Unit Treatment Capacity Table
Chapter 7 -Vortechs System Data
Attachments
BMP Location Map
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La Costa Greens Neighborhood 1.6
Storm Water Management Plan
CHAPTER 1 -EXECUTIVE SUMMARY
1.1 -Introduction
The La Costa Greens Neighborhood 1.6 site is located at the north eastern corner of
the intersection of Poinsettia Lane and Alicante Road in the City of Carlsbad,
California (see Vicinity Map). The 36-acre site is bounded to the north-east by the
existing Bressi Ranch residential development and bounded to the east by the
proposed La Costa Greens Neighborhood 1.7 residential development.
~171-
LA COSTA VIClNfTYMAP
/'/15
All runoff from the site ~ill drain south to the Alicante detention basin, south of
Poinsettia Lane, ultimately draining to an unnamed tributary of San Marcos Creek.
Runoff from this tributary eventually discharges into San Marcos Creek towards the
Batiquitos Lagoon.
Per the City of Carlsbad SUSMP, the La Costa Greens Neighborhoods 1.6 project is
classified as a Priority Project and subject to the City's Permanent Storm Water BMP
Requirements.
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La Costa Greens Neighborhood 1,6
Storm Water Management Plan
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 site Best Management Practices
(BMPs) which include a single Vortechs treatment unit (see BMP Location Map in
this chapter).
Furthermore, this report determines anticipated project pollutants, pollutants of
concern in the receiving watershed, peak flow mitigation, recommended source
control BMPs, and methodology used for the design of flow-based and volume-
based BMPs.
1.2 -Summary of Pre-Developed Conditions
The site is located north of Poinsettia Lane, east of Alicante Road, and west of the
proposed La Costa Greens Neighborhood 1.07 (see Vicinity Map). Located in the
Batiquitos watershed, the site consists of primarily hilly, undisturbed terrain covered .r
with natural vegetation. The site receives offsite runoff from the adjacent Bressi
Ranch residential development to the north-west.
Peak flow data from the adjacent Bressi Ranch development, was obtained from the
referenced PDC plans, attributing 30.6 cfs to the proposed site in ultimate developed
conditions.
Natural runoff from the undeveloped site flows in a southerly and westerly directions
towards Poinsettia Lane and Alicante Road respectively. Flow directed towards
Alicante Road is collected via an existing 0-34 Headwall, flowing into a 36" RCP and
draining southerly through the storm drain located within Alicante Road to the
Alicante detention basin. Flow directed towards Poinsettia Lane is intercepted by a
D-34 headwall, discharging to 24" RCP culvert, which discharges beneath Poinsettia
Lane directly to the Alicante detention basin.
Per the "Improvement and utility plans for Alicante Road, Dwg.# 400-8J", by
Hunsaker & Associates San Diego, Inc. and also per the "Grading and drainage
plans for Poinsettia Lane, Dwg.# 397-2H", dated 1/24/03 by Kimley-Horn and
Associates, existing flows at the points of discharge were attained for Alicante Road
and Poinsettia Lane respectively.
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La Costa Greens Neighborhood 1.6
Storm Water Management Plan
Table 1 -Summary of Pre-Developed Conditions
Drainage Location 100-Year Peak Flow
(cfs)
Alicante Road 85.5 (36" RCP)
Poinsettia Lane 38.3 '(24" RCP)
Flow from this basin then flows southwards to an unnamed tributary of San Marcos
Creek, which then flows in a southerly direction along the site boundary of the La
Costa Greens Golf Course, west of the Phase I development area. All the runoff
eventually drains under Alga Road via three 96" RCP culverts, as shown in Drawing
No. '397-2, and discharges into San Marcos Creek towards the Batiquitos Lagoon.
Per the "Improvement and utility plans for Alicante Road, Dwg.# 397-2F", by O'Day
Consultants, there is an existing Vortechs Model 3000 treatment unit within the
existing storm drain in Alicante Road to which the proposed Neighborhood 1.6
drains to. This unit was constructed specifically to treat expected development of
the 1.6 site, and as such has been sized to accommodate the proposed treatment
flow.
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 36-acre area will consist of 91 single-family residences,
associated roads, foot paths, communal open space, onsite parking and
underground utilities with a single entrance from the adjacent Alicante Road.
Runoff from the proposed 36-acre developed area will drain to two (2) points of
discharge. The eastern body of development will drain easterlY along Street "A",
where run off will be collected by road inlets, flowing easterly in the storm drain
within Street "A". This storm drain then enters Neighborhood 1.7 where it continues
to collect run off from the bordering development before discharging to the existing
48" RCP headwall in Poinsettia Lane, draining to the Alicante detention basin. For
more information of the proposed storm drain system within La Costa Greens
Neighborhood 1.7, refer to the "Drainage Study for La Costa Greens Neighborhoods
1.6 & 1.7" by Hunsaker & Associates San Diego, Inc. January, 2005.
Run off from the west of the development, inclusive of the offsite drainage from the
Bressi Ranch residential development, will drain west to Street "B" where it will exit
to the existing 36" RCP headwall at Alicante Road. Once the storm water
discharges to the existing 36" RCP, storm water will be conveyed south within the
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LA COSTA
GREENS 1.6
CITY OF SAN DIEGO, CAUFORNIA
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La Costa Greens Neighborhood 1.6
Storm Water Management Plan
Alicante Road storm drain system. Before entering the existing Alicante detention
basin, this runoff is treated via the existing Vortechs Model 3000 treatment unit
within the existing storm drain. .
Development of the site will not cause any diversion to or from the existing
watershed'to the storm drain system.
85th percentile runoff will be treated in storm water BMPs prior to discharge to the
detention basin.
Based on County of San Diego criteria a runoff coefficient of Q55 was assumed for
the proposed single-family residential development.
The storm water from the eastern development is treated via the flow based BMP
located within La Costa Greens Neighborhood 1.7. Refer to the "Storm Water
Management Plan for La Costa Greens Neighborhood 1.7", dated January 2005 by
Hunsaker & Associates San Diego, Inc. for further information on this unit.
1.4 -Results and Recommendations
Table 2 below summarizes rational method 85th percentile calculations for the
existing water quality treatment unit for the La Costa Greens Neighborhood 1.6
development.
Table 2 -Developed Conditions 85th Percentile Calculations
Drainage 85tn
Rainfall 85th
Treatment Percentile Runoff
Unit Area Rainfall Intensity Coefficient Percentile
(acres) (inches) (inches/hour) -Flow (cfs)
Alicante 32.4 0.67 0.2 0.55 3.6 Road BMP
Rational Method calculations predicted an 85th percentile runoff flow of roughly 3.6
cfs for the area discharging to the treatment unit. 85th percentile flows will be treated
in the existing Vortechs Model 3000 unit within Alicante Road.
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La Costa Greens Neighborhood 1.6
Storm Water Management Plan
The existing Vortechs unit is an offline precast 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.
As part of the improvements to Alicante Road, the existing Vortech Model 3000 unit
was sized and constructed in anticipation of development to the Neighborhood 1.6
site. The unit has a treatment flow capacity of 4.5 cfs, thus is sufficient to treat the
85th percentile runoff from the proposed project.
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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La Costa Greens Neighborhood 1.6
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), whicb 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 Greens Neighborhood 1.6 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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APPENDlXA
STORM WATER REQUIREMENTS APPLlCABILlTY CHECKLlST . .
. Complete Sections 1 and 2 of the following ·checklist to determine your pro]ect1s
permanent and construction .stol}11 water best management pradicss requirements.
This form must be completed-and submitted with your permit application. .
Section 1. Permanent Stann Water EMP Raquiremenls:
If any answers to Part A are answered "Yes," your project is subject to the' IIPrioriiy
Project Permanent Storm Water. BMP ReqlJirements," and IIStandard Permanent Storm
Water 8MP Requirements" in Section Ill, "Permanent Storm Water 8MP Selection
Procedure" in the Storm Water Standards manual.
If all answers to Part A are "No,",and any answers to Part Bare "Yes,JI your project is
only subject to the UStandard Permanent Storm Water' EMP Requirementsl', If ~very
question in Part A and 8 is answered "Nol
ll your project is exempt from permanent
storm water reqUirements. . ..
Part A: Determine Priorlty Project Permanent Storm Water EMF Requirements.
Does the project meet the definition of one or more of the priority project Yes No cateqories7*
1. Detached residential development of 10 or,more units v I
2. Attached residential development of 10 or mars units " 3. Commercial development greater than 1 OQ, 000 square feet .j
4. Automotive repair shop ~ 5. Restaurant
6. steep. hillside development greater ihan 5,000 square feet .,j
7. Project dischar~inq to receiving waters within Environmentally S~nsitive Areas 1/,
8. Parking lots greater than or equal to 5, 000 it'" or with at least 15 parking spac:es, and / potentlallv exposed to urban runoff
9. Streets, roads, highways, and freeways which would cre2te a new paved surface that is I. 5,000 square feet or 9reater
* Refer to the deiinitions section in the storm Wafer Standards for expanded deiiniilons of the priority
project categories.
Limited Exclusion: Trenching and resurfacing work associated with utilIty projects are not considered
priority prolects. Parking lots, buildings and other structures associated with utility projects are
priority projects if one Of more at the criteria In PC3rt A is met. If all answe"rs to Part A are "No",
continue to Part 8.
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I La Costa Greens Neighborhood 1.6
Storm Water Management Plan
I CHAPTER 3 -IDENTIFICATION OF TYPICAL POLLUTANTS
I 3.1 -Anticipated Pollutants from Project Site
The following table details typical anticipated and potential pollutants generated by
I various land use types. The La Costa Greens Neighborhoods 1.6 development will
consist of detached single-family residence. Thus, the Detached Residential
Development categories have been highlighted to clearly illustrate which general
I pollutant categories are anticipated from the project area.
I II) en II)
(1)
II) "C II)
Priority c c (1) cu ~ II) -II) .-(,) e (1) c -(,) ::I c"C C .!!! II) "C Project (1) c >.(1) .-0 ~II) (1) C cu (!) .. (1) 'u E (1) CQ, .c .-en cu 1i) (1) II) I Categories . ;: >-cu E II) .. ~ :0::: :c -cuS E'o cu,c >oED 0::1 II)
(1) ::I (1) (1) .. (1) >< (1) ::I 0 cu.!:: (1) en z :I::! 00 I-C Ocen m> Il.
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Commercial
Development p(1) p(1) p(2) X p(5) X p(3) p(5)
I >100 fe
Automotive
Repair X X(4)(5) X X
I Sho
Restaurants X X X X
I Hillside
Development X X X X X X
000 fe
I Parking Lots p(1) p(1) X X p(1) X p(1)
Streets,
Highways & X p(1) X X(4) X p(5) X
I Retail Gas X X(4) X X Outlets
I X=
P = potential
(1) A potential pollutant if landscaping exists on-site.
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(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 Greens Neighborhood 1.6
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 c~n 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 Greens Neighborhood 1.6
Storm Water Management Plan
3.7 -Bacteria & Viruses
Bacteria and viruses are ubiquitous micro-organisms that thrive under certain
environmental conditions. Their proliferation is typically caused by the transport of
animal 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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La Costa Greens Nefghborhood 1.6
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-deve~oped La Costa
Greens Neighborhoods 1.6 site drains to an unnamed tributary of San Marcos Creek
which eventually discharges to the Batiquitos Lagoon within the San Marcos Creek
watershed.
Development of the site will not cause any diversion to or from the existing
watershed to the storm drain system.
The Regional Water Quality Control Board has identified San Marcos Creek as part
of the Carlsbad Hydrologic Unit, San Marcos Creek Watershed, 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 the Batiquitos Lagoon and San Marcos Creek includes
agricultural supply, contact water recreation, non-contact recreation, warm
freshwater habitat, and wildlife habitat.
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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Sedimentation / , Siltation
27 Los Monos HSA
Agua Hedionda I rf Total Dissolved (904.31) C k . ower po IOn Solids· lower? miles 2002 I ree , 28 San Marcos HA Pacific Ocean at Moonlight State Beach Bacterial
(904.50) Shoreline • IndicatorsE 0.4 miles 1998
I 29 Escondido Creek Pacific Ocean Bacterial , HA (904.60) Shoreline at San Elijo Lagoon
IndicatorsE 0.44 miles 1998
30 San Elijo HSA . San Enjo Bacterial
I (904.61) Lagoon IndicatorsE 150 acres. 1998 , Eutroehic 330 acres
Sedimentation / 150
S'lt f acres I I a IOn .
31 San Dleguito HU Pacific Ocean at San Dieguito Lagoon Mouth Bacteri~li .0.86 miles (905.00) . Shoreline IndicatorsE 1998
32 Del Dios HSA " Green Valley I (905.21· and Sulfate 1 mile 2002
905.22) Creek
3~ Del Dios HSA Hodges Entire Resef\loir Color Entire 2002 , (905.21) Reservoir Nitrogen Reservoir
Phosehorus (1104 acres)
J Total Dissolved , Solids
34 Felicita HSA Total Dissolved lower 0.92 , (905.23) Felicita Creek Solids miles 2002
-35 Felicita HSA Kit Carson Total Dissolved (995.23) should in 905.21 HSA 1 mile 2002 , Creek Solids
36 Highland HSA Phosphorus 1.2 miles 2002
(905.32) Cloverdale Total Dissolved t Creek Solids
37 Sutherland HSA Sutherland Entire Reservoir Color Entire 2002 l!"!I (905.53) Reservoir Reserioir , 38 Miramar Reservoir Los Sedimentation I 469 HA (906.10) Penasquitos Entire Lagoon SOlt f acres 1998
La200n I a Ion -~ , 39 Miramar Resel"l/Qir Pacific Ocean Torrey Pines State Beach at Del Bacterial 0.4 miles 2002 HA (906.10) Shoreline Mar (Anderson Canyon) IndicatorsE
40 Scripps HA La Jolla Shore$ Beach at El Paseo 3.9 miles 1998 , (906.30) Pacific Ocean Grande Bacterial
Shoreline La Jolla Shores B~ac~ _atCClminito IndicatorsE
Del Oro
• La Jolla Shores Beach at
Vallecitos
La Jolla Shores Beach at Ave de la ;t1 Playa , last updated 9123/2003
page 3 of 6 ~ S:\WQS\303dlist\SD Staff Raport-2Q02\FINAL VERS10NS\Ustad Waterbodies-2D02.xls\Table 4 {Sep03 .< ~-~.
Table 2-2. BENEFICIAL USES OF INLAND SURFACE WATERS
BENEFICIAL USE
1,2 M A I P G F P R R B W C .w
Hydrologic Unit U G N R W 'R 0 E E I A 0 I Inland Surface Waters BasIn Number N R D 0 R S W C C '0 R L L
-C H 1 2 L M D 0
San' Diego County Coastal Streams -contII1U1~d
Buena Vista Lagoon 4.21 See Coastal Wfjt!3rs-Table 2-3
Buena Vista Creek 4.22 + 0 fi • II • ••
BUena Vista Creel< 4.21 + 0 II • • • •
Agua HedJonda 4.31 See Coastal Waters-Table 2-3
Agua Hedionda Creek 4.32 CD • e CD • • ..
I Buena Creek 4.32 (I It 9 • • • II
Nlua Hedionda Creek 4.31 4iI 0 0 ., o. • • , : : Letterbox canyon 4.31 eI e ., : ,. • II •
Canyon de las Encinas 4.40 + 0 • • •
San Marcos Creek Watershed
Batlqultos Lagoon 4.51 See Coastal Waters-Table 2-3
San Marcos Creek 4.52 + • • • • •
unnamed Intermittent streams 4.53 + e • • • •
San Marcos Creek Wat.ershed
San Marcos Creek 4.51 + it • • • •
il EnCinitas Creek 4.51 + • • • • • I
1 Waterbodies are listed mulliple tImes If they cross hydrologio area or sub area boundaries. • Exi5ting Benefioial Use
o Potenllal Bef!eficial Use 2 Beneficial use designations apply to all tributaries to Ihe indicated waterbody, if not listed separately_
+ Excepled from MUN (See Text)
Tabla 2-2
BENEFICIAL USES 2-27
R S
A P
R W
E N
"
March 12, 1997
'~" __ C~""'"'_l;>:":' t;"""':;_~'~_J~~_iJ':'J 'E!;'''''~'_' .~ ':'~ .. _ ""'_ .... -.---._--.. - - - -
Table 2-3. BENEFICIAL· USES OF COAS'TAL WATERS
BENEFICIAL USE
Coastal Waters Hydrologic I N R R C B E' W R
Unit Basin N A E E .0 I S I A
Number 0 V C ·c M 0 T L R
1 2 M L 0 E
Pacific Ocean • e; G e flit • •• G
Dana Point Harbor tAl • e' e " 0 6)
Del Mar Boat Basin (9 (; O· • • • *' Mission Bay • • tl:) ., e • e
Oceanside Harbor @ 8 e (0 • e " . I San Diego Bay 1 • CD • fJ • ~ • e ,0
Coastal fagoons
• Tijuana River Estuary
J
11.11 @) " • • • • 0
Mouth of San Diego River 7.11 • e • • e ..
Los Penasquito5 Lagoon 2. 6.10 G @ 0 • • •
San Diegulto Lagoon 5.11 @ • $ ., e' ..
Batiquitos.Lagoon 4.51 • ., .S • • •
San Elijo Lagoon . 5.61 (I f) •• " " 8
Aqua' Hedionda .Lagoon 4.31-e • e e ., • .,
Includes the tidal prisms of the Otay anel Sweetwater Rivers.
2. Fishing from shore or boat permitted, but other water contact recre.ational IREC-1) uses are prohibited.
e Existing B8n~fiGJal US6
Tabla 2-3
BENEFICIAL USES 2-47'
M A M S W ~ . A Q I P A
R U G W R E
A fl N M L
L
• • • $. e .. • e 0
• " • " • (8 e' til)
• ., " 0
• ., ., °1 '.
• : ., ., " .. • e G
• • • G
• ., .,
• ., •
G • ., ., G • .. Cit
March 12, 1,997
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Table 3-3" WATER QUALITY OBJECTIVES
Concentr.fltlons not to be exceeded more than 10% ,of the time during anyone year period.
Constituent (mg/L or as noted)
Ground Water Hydrologic Turb Color Basin Unit TDS CI SO'!-%Na NOa Fe Mn .MBAS 8 ODOR NTU Units F
Number
Buena Vista Creek HA 4.20
EI Salta HSA a 4,21 3500 BOO 500 60, 45 0.3 0.05 0.5 2.0 nona 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 0.75 b none 5 15 1.0
' -Agua Hedlonda HA a 4.30 1200 500 500 60 10 0,3 0,05 0.5 0.75 none 5 15 1.0
los Monos HSA aj 4.31 3500 800 500 60 45 0.3 0.05 0.6 2.0 none 5 15 1.0
Encinas' HA a 4.40 3500 b 800 b 500 b 60 45 b 0.3 b 0,05 b . 0.5 2.0 b none 5 15 1.0
San Marcos HA ae· 4.50 1000 400 500 " 60 10 0.3 0.05 0.6 0.75 none 5 15 1.0
Batlquitos HSA ask 4.51 3500 BOO 500 60 45 0.3 0.05 0.5 2.0 none 6 15 1.0
Escondido Creek HA a 4.60 750 300 300 60 10 0.3 0.05 0.5 0.75 none 5 15 1.0
San Elljo . HSA a 4.61 2800 700 600 60 46 0.3 0.05 0.5 1.0 none 5 15 1.0
Escondido HSA 4.62 1000 300 400 60 10 0.3 ' 0.95. 0.5 0.75 none '5 15 1.0 i
I SAN DJE~UITO HYDROLOGIC UNI; 905.00 I
Solana Beach .. HA 9 5.10 1500 b 500 b 600 b 60 45 b 0.85 b 0,15 b 0,5 ,0,75 b none 5 15 1.0
Hodges HA 5,20 1000 b 400 b 500 b 60 10 b 0.3 b 0.05 b d.6 0,76 b none 5 15 1.!)'
San Pasqual HA 5,30 1000 b 400 b 500 b 60 10 b 0.3 b 0.05 b 0.5 0.75 b none 5 15 1.0
Santa Maria 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 5.50 500 250 250 60 5 0.3 0.05 0.5 0,75 none 5 15 1.0
PENASQUITOS HYDROLOGIC UNIT £106.00
Miramar Reservoir HA at 6.10 1200 500 500 60 10 0.3 0.05 0.5 0.75 none 5 15 1.0
Poway' HA 6,2.0 750 q 300 300 fiO 10 0,3 0,05 0.5 0.75 none 5 15 1.0
Scripps HA 6.30 -------------
Miramar HA g 6.40 7110 300 300 60 10 0,3 0.05 0.5 0.76 none 5 15 1..0
Tecolote HA 6.50 ---------------
HA -Hydrologic Area
HSA -~lydroloolG Sub Arell iLower [las .. leiters Indicate endnota~ following the table.!
Table 3-3
WATER QUALITY OBJECTIVES Paga 3-29 October 13. 1994
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La Costa Greens Neighborhood 1.6
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 C -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 G~eens Neighborhood 1.6
Storm Water Management Plan
Other features of the Vortechs Systems include the foTfowing:
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
c1eanout
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 BMP Categories
Hydrodynamic
Separation
Devices(2)
(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 Areas 001
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La Costa Greens Neighborhood 1.6
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 maintena~ce 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 tba.amounLof.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 mllst 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.
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La Costa Greens Neighborhood 1.6
Storm Water Management Plan
The facility will be inspected regularly and inspection visits will be completely
documented:
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 dee,:;> (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 Vorte_cbs _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 maintenal1ce 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 (Le .• 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
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La Costa Greens Neighborhood 1.6
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 Greens Neighborhoods.
Approximate annual maintenance costs for the existing Vortechs unit are outlined
below. Costs assume a 3 man crew:
Maintenance for Vortechs Model 3000:
Periodic Inspection, Maintenance and Monitoring = $8,00
Annual Cleanout Cost = $1,000
Subtotal = $1,800
Contingency = $180
Total = $1,980
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La Costa Greens Neighborhood 1.6
Storm Water Management Plan
CHAPTER 6 -SOURCE CONTROL BMPS
6~1 -Landscaping
Manufactured slopes shall be landscaped with suitable ground cover or installed with
an erosion control system. Homeowners 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.
6.2 -Urban Housekeeping
Fertilizer applied by homeowners, in addition to organic matter such as leaves and
lawn clippings, all re.sult 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 Greens Neighborhood 1.6
Storm Water Management Plan
6.3 -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 unlawfut
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.
Dis-ch-arges 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. A::
monitoring program should also be implemented to insure <?ompliance. ~;'
6.4 -Site Design BMPs
Priority projects, such as the La Costa Greens Neighborhood 1.6 development, 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 landscapin'g design is
discussed in section 6.1.
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 example for
minimizing impervious area includes incorporating landscaped areas in the
drainage system to encourage infiltration and reduce the amount of directly
connected impervious areas. ,
-Minimizing directly connected Impervious Areas. Where landscaping is
proposed, drain rooftops into adjacent landscaping prior to discharging to the
storm water conveyance system.
For the proposed 36 acre site, 6.4 acres (approximately 17.7%) will remain totally
pervious.
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La Costa Greens Neighborhood 1.6
Storm Water Management Plan
CHAPTER 7 -SITE BMP DESIGN
VORTECHS TREATMENT UNITS
7.1 -BMP Locations
The site design includes a single Vortechs treatment unit (shown on BMP Location
Map located on the following page). The existing unit is located with the existing
storm drain within Alicante Road, prior to discharging to the Alicante Road basin.
7.2 -Determination of Design Treatment Flows
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) = 0.55
Rainfall Intensity (I) = 0.20 inches per hour
Drainage area to treatment unit (A) = 32.4 Ac.
.) The following table summarizes the parameters used for determination of design
flow to the Vortechs treatment unit. " "
DESIGN RUNOFF DETERMINATION SUMMARY TABLE
Runoff 85m
Drainage 85th Pct. Percentile Treatment Unit Coefficient Rainfall Area Design-Flow
(C) (inches/hour) (acres) (cfs)
West Storm 0.55 0.2 32.4 3.6 -Drain Unit
7.3 -Vortechs Treatment Unit Selection
The existing Vortechs unit is an offline precast 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 following table shows, the treatment capacities of the existing Vortechs unit.
VORTECHS UNIT TREATMENT CAPACITY TABLE
8510 Pct.
Treatment Unit Design Flow
,(cfs)
Existing Model 3000 3.6
Recommended
Vortechs
Model
3000
Treatment Capacity
(cfs)
4.5
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85TH PERCENTILE PEAK FLOW AND VOLUME DETERMINATION
Modified Rational Method -Effective for Watersheds < 1.0 mi 2
Hunsaker & Associates -San Diego
Note: Only Enter Values in Boxes -Spreadsheet Will Calculate Remaining Values
Project Name La Costa Greens 1.6 I
Work Order 2352-106 I
Jurisdiction City of Carlsbad I
BMP Location IWestern Storm Drain -Existing BMP in Alicante Road
85th Percentile Rainfall = 0.67 linches
(from County Isopluvial Map)
Developed Drainage Area = acres
Natural Draina e Area = acres
Total Drainage Area to BMP = acres
Dev. Area Percent Impervious = I 26 Wo
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=
1=
A=
Q=
C=
P=
A=
Using the Total Drainage Area:
C=
1=
P=
A=
Q=
V=
Using Developed Area Only:
C=
1=
P=
A=
Q=
V=
26 %
10.4 Iminutes
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
0.55
0.2 inch/hour
0.67 inches
32.4 acres
3.56 cfs
0.99 acre-feet
0.55
0.2 inch/hour
0.67 inches
32.4 acres
3.56 cfs
0.99 acre-feet
,
• J' , -
1<
.. ...:
',)
,. The Vortechs Stonnwcrter Trecrtm~t ~ym~m~ ~~~d:::nt
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in oU 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 8a% 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-
abIes from escaping the system during cleanout
Vortechs Systems may be
used in a wide range of
water-quality improvement
applications, including:
VVetland~aterfront
Protection
Retail
Development
Industrial Sites
Municipal Improvements
C'ommercial DeV:elopment
Transportation Facilities
Existing Site Retrofits
"We have worked with
Vortechnics on at least a
dozen storm water
f!1anagement plans for
some of our largest
corporate clients. Their
efficient turnamund on
our requests for technical
support and GADD
drawings has expedited
the permitting process
for our clients. We turn
to Vortechnics when
we need innovative
storm water solutions. "
-Lawrence Marsiglia, RE.
Senior Civil Engineer,
Barakas-Landina, Inc.
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1) Initial Wet Weather Phase
During a. two-month storm event the water lev!?1 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, stomn
drains are flowing at peak capacity. The Vortechs System is
designed to match your design storm flow and provide treat-
ment thrqughout 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·filis arid 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 f10atables to the
outlet during cleaning t;ilr during the next storm.
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the Stormwater Treatment
11 .... -----0 Plus 6' Typical -----... 1
~ 1/4'Th~~~;/
~(0)
Offset .,.-
' .. ---'"
1'-10' 1'-9' '-9' ---
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 of charge.
Ii . 6' to 91 L ______ / I
3'tIJ5'
Typical j .-INV.~ -t-
3'tIJ4'
Elevation View
,', " ": ~':., " " ,',' .. ': ,-,._ '.' ... ."":' " Engineering Notes" . --""':.:;';:, ~' ......... : ... :'::'. '.:":" ,':.':.";,"'" .: .. '
. Ai For in-line Vortechs ~t~ms 'without' a:bypa~s, sizing' crite~ia 'is ba~ed on' providing' ~r\e ~~'u~re' ioot.·af'~rit ".' .
. chamber surfac~'area for each 100 gpm of· peak aesign stIJrm flow rate [e.g .. ,O-year·storm). For niore "
deteils abot,Jt Vortechnics sizing.c~iterie refer tIJ Vortechnics Technical Bulletin 3,: .', , .',.": ::: ...... ' ,. :", '.:", :.' ..
B) Sediment storage volume assumes a 3 foo't sump.:. ". , ,. .' .' _ .. :' __ :." " '." .' ;' .:'. : : ...
C)· Construction det~ils may vary depending on 'the specific application. Any' alterations ;il th~ sizing"cha'r;; spe'cin:
cations will appear on Vortechnics dimensional and shop drawings. Please call Vortechnics for the weight of spe-.
'cific Vortechs systems if needed. .... .. . . . '. :'. .. ... :'. '.' . :'. '.' '" .. ' '.' ": .
Special Note: Pil ~torage c~pacity, wh~n it 'is ~eedei:l to rri~et a' s~e~ifi~' requi~ement fdr' spill co~t8irime~t, can:be
. sized to meet the storage requirement with the selected model. Vortechnics technical' staff will optimize system
. geometry to meet con~ainment requirements within.8 correctiy sized Vortechs Systsm.. " .' < ... '
Metric Sp'e~ification 'Ch~~t aVailabl~ b~ c~"ing Vortech~ics at [207) 878-3862. . " .
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.
I)II L
End Inlet
To
Polish
-
To
Outfall
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SECTION 02721
STORMWATER TREATMENT SYSTEM
PART 1.00 GENERAL
1.01
1.02
DESCRIPTION
A. Work included:
The Contractor, and/or a manufacturer selected by the Contractor and approved
by the Engineer, shall furnish aWlauor, 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
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.
C.
Ali 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 befone final acceptance. Cement mortar
used for repairs shall have a minimum compress'ive 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 SUBMITIALS
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 infrir:\gement 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 co~~orming to ASTM C 990.
3. Cement shall be Type III Portland cement conforming to ASTM C 150.
4. Pipe openings shall be si~ed 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
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2.02
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.
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 Storage Model Diameter Capacity
(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
7000 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 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 sedimenfstorage 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 Page 3
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that the pump-out volume is less than % 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
at! 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, Portland, 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 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 qther corner exceeds 0.5% the
base section shall be removed and the granular subbase material re-Ieveled.
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 TI 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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~.~~~'. 'j"!, •• ~
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E.
F.
G.
H.
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 affi?<ed to the floor with a minimum 3/S" 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.
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 ~f
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
ap.ply non-shrink grout to the joints at the side edges of the baffle wall.
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 CS91 "Standard Practice For Installation of Underground Precast
Utility Structures".
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.
Where holes must be cut in the prE?cast 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.
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VORTECHS™ STORMWATER TREATMENT SYSTEM
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 will provide a net annual removal efficiency in excess of 80% removal of
Total Suspended Solids 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 (Le. 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 on the design conditions provided. 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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VORTECHS™ 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.
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 the
model number is chosen based on the grit chamber area such that 24 gpm/sf of flow is realized
through the chamber.
Sump: 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 may vary to balance maintenance costs with capital costs.
Orifice: The function of the orifice is to raise the water level in the Vortechs System. This
increases the area 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 keeping the trapped
sediment and f10atables contained. In addition, the rise in water level causes the f10atables to
rise above the inlet and away from the baffle opening, thus preventing the floatables 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.
Weir: Any event greater than the 2-month event causes the water level in the Vortechs System
to rise to the upper flow control, submerging the inlet. The upper flow control is normally a
Cippoletti 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 water 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
the design flow rate minus the orifice flow at full head.
Baffle: The baffle opening is designed to maintain a velocity such that re-entrainment of
floatables and re-suspension of sediment is minimized. The baffle opening is at least 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 upstream of the specified Vortechs System. The
goal is to achieve a water surface elevation 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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TM VORTECHS STORMWATER TREATMENT SYSTEM
Flow Control Calclliations 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 10 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 2751
divided by 38.5 or 72 gpm/sf. '
The low flow control is a trapezoidal orifice (QOrifice). 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 Technicar Bulletin #3, the 2-month storm
flow rate is approximately equal to the 10-year flow rate divided 'by 7. The orifice calculation
based on the'full design flow is as follows:
Q2-monlh =. Q10year+ 7 = 6.13 + 7 = 0.88 cfs
Qorifice = C(A)(29h)0.5 = 0.56(0.14)(2.0 x 32.2 x 2.0) O.s = 0.89 cfs 4
Where C = Orifice contraction coefficient = 0.56 (based on Vortechnics laboratory testing)
A = Orifice flow area, fe (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 (Qweir) which is
conservatively designed for the system design flow (QdeSign) of 6.13 cfs. The weir
calculations, are as follows:
Qweir = 6.13 cfs
Qweir = C(L) (H) 1.5 = 3.37(0.50)(2.42)1.5 = 6.34 cfs 4
Where C = Cippoletti Weir coefficient = 3.37 (based on Vortechnics laboratory testing)
H = Available head, ft (height of weir)
L = Design weir crest length, ft (calculated by Vortechnics technical staff)
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VO~TECHSTM STORMWATER TREATMENT SYSTEM
MAINTENANCE
The Vortechs System requires minimal routine maintenance. However, it is important" that the
system be insp~cted 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
activities than the size of the unit, e.g., heavy winter sanding will cause tne 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 tt:? 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 manhole opening to the water
surface. If the difference between the two measurements is less than six inches the system
should be cleaned out. Note: to avoid underestimating the volume of sediment in 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 than 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 va:cuum truck is generally the most effective and
convenient method. Cleanout should not occur within 6 hours of a rain event to allow the entire
collection 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 to remove water and contaminants. However, all
chambers should be checked to ensure the integrity of the system. In installations where a
"clamshell" is being utilized for solids removal, prior to removing the grit, absorbent pads or
pillows can be placed in the oil chamber to remove floating contaminants. Once this is done,
sediment may then be easily removed with the clamshell.
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VORTECHS™ 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
tliat surface runottdoes not leak into the unit from above.
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La Costa Greens Neighborhood 1.6
Storm Water Management Plan
CHAPTER 8 -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.
"TM Drainage-Study for La Costa Greens Neighborhood 1.7",. Hunsaker &
Associates San Diego, Inc.; November, 2004.
"TM Drainage Study for La Costa Greens Neighborhood 1.6", Hunsaker &
Associates San Diego, Inc.; November, 2004.
"Drainage Study for La Costa Greens Neighborhoods 1.06 & 1.07", Hunsaker &
Associates San Diego, Inc.; January 2005.
"Storm Water Management Plan for La Costa Greens Neighborhood 1.7", Hunsaker
& Associates San Diego, Inc.; January 2005.
"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 Sectio':1; 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.
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PREPARED BY:
HUNSAKER
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SAN DIEGO, INC.
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BMP LOCATION MAP FOR
LA COSTA GREENS
NEIGHBORHOOD 1.06
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