HomeMy WebLinkAboutEA 09-07; Coastal Rail Trail Reach 1; Administrative Permits (ADMIN) (5)I
Storm Water Management Plan (SWMP)
(Non-Priority Project)
Project Identification:
Applicant:
SWMP Prepared by:
Coastal Rail Trail -Reach 1
Carlsbad, CA
Contract No. 3455
City of Carlsbad
1635 Faraday Avenue
Carlsbad, CA 92008
Contact Person: Jon Schauble
Phone: (760) 602-2762
CONSULTING
Contact Person:
RBF Consulting
5050 Avenida Encinas. Suite 260
Carlsbad, California 92008-4386
760.476.9193 telephone I 760.476.9198 fax
Katharine E. Maker, RCE 75061
RBF JN 55-100827.001
Initial Preparation Date: September 17.2012
Revision Date(s):
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Table of Contents
1 PURPOSE AND SCOPE ............................................................................................. 1
2 PROJECT INFORMATION ....................................................................................... 2
2.1 Project Description .................................................................................................. 2
2.2 Project Activities ..................................................................................................... 3
3 WATER QUALITY POLLUTANTS OF CONCERN ............................................... 5
3.1 Potential Pollutants .................................................................................................. 5
3.2 Primary Pollutants of Concern ................................................................................. 8
4 WATER QUALITY CONDITIONS OF CONCERN ............................................... 10
5 STANDARD STORMWATERREQUIREMENTS ................................................. 11
5.1 Minimize Impervious Surfaces .............................................................................. 11
5.2 Disconnect Impervious Discharges ........................................................................ 11
5.3 Conserve Natural Areas ......................................................................................... 11
5.4 Stenciling Inlets and Signage ................................................................................. 11
5.5 Landscape Design .................................................................................................. 11
5.6 Water Efficient Landscaping .................................................................................. 11
5.7 Protect Slopes and Channels .................................................................................. 12
5.8 Trash Receptacles .................................................................................................. 12
5.9 Material Storage Areas .......................................................................................... 12
5.10 Vegetated Buffer Strip ........................................................................................ 12
5 .11 Drain Inserts....................................................................................................... 12
6 BMP MAINTENANCE PROVISIONS ..................................................................... 13
6.1 Landscape Maintenance ......................................................................................... 13
6.2 Vegetated Buffer Strip Maintenance ...................................................................... 13
6.3 Drain Inserts Maintenance ..................................................................................... 14
Table of Figures
Figure 2.1 Vicinity Map ........................................................................................................ 4
List of Tables
Table 3-1 Anticipated and Potential Pollutants Generated by Land Use Type ........................ 5
Table 3-2 Summary of Receiving Surface Waters ................................................................. 8
Appendix
Appendix A-Storm Water Standards Questionnaire
Appendix B-BMP Fact Sheets
Appendix C-BMP Site Plan
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1 PURPOSEANDSCOPE
Storm Water Management Plan
Coastal Rail Trail-Reach 1
The City of Carlsbad's Storm Water Management and Discharge Control Ordinance
(Carlsbad Municipal Code Chapter 15.12) requires all development permit applications to
complete the storm water standards questionnaire (E-34). The purpose of the questionnaire is
to determine what type of storm water requirements the project must meet. For the Carlsbad
Coastal Rail Trail, Reach 1 the project is considered a significant redevelopment and therefore
Section 2 of the questionnaire was completed. It was determined that the project is not a
priority project and is subject to 'Standard Stormwater Requirements' only, and shall
incorporate methods to minimize the introduction of pollutants generated by urban runoff
from the project.
1
2 PROJECT INFORMATION
2.1 Project Description
Storm Water Management Plan
Coastal Rail Trail-Reach 1
The project is located along State Street and Carlsbad Boulevard/Coast Highway, from Eaton
Street in the City of Oceanside to Oak Avenue, in the City of Carlsbad, CA. A roundabout is
proposed at the State Street I Carlsbad Boulevard intersection. Figure 2.1 provides a location
map for the project.
The county-wide Coastal Rail Trail project proposes a non-motorized trail, primarily within
the San Diego Northern Railroad (SDNR) right-of-way (R/W). The trail includes segments of
8' wide multi-use Class I paved paths, 5' wide Class II bike lanes, and Class III bike routes
within existing roadways. The Class I pathway will be separated by a 3' barrier and run the
length of the project corridor, proposed amenities include landscaping, irrigation, trash
containers, bicycle racks, and signs.
In the City of Carlsbad the Coastal Rail Trail is divided into 5 reaches. This report supports
the construction ofthe Reach I portion, which begins at Eaton Street in the City of Oceanside
and extends south through the State Street and Carlsbad Boulevard intersection. The trail
continues as a Class III bike route along State Street until the Oak A venue and State Street
Intersection, where the trail accesses the eastern edge of the railroad right-of-way. The
proposed improvements include the construction of a 1 0' wide Class I bike path, Class II bike
lanes, and Class III bike routes. A single-lane roundabout is proposed at the State Street and
Carlsbad Boulevard intersection.
2
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2.2 Project Activities
Storm Water Management Plan
Coastal Rail Trail-Reach 1
The project is considered a road narrowing and sidewalk and bike facility improvement
project, and activities on the site will be typical of such development (i.e. travel lanes, bike
facilities, walkways, landscaped areas). The project is not anticipated to generate significant
food or animal waste products.
It is important to note, the project is divided into two drainage areas (See BMP Concept Plan
in Appendix C). Drainage Area A extends from Eaton Street to the existing bridge. Drainage
Area B extends from the existing bridge to Laguna Drive, along State Street, and to the
existing bridge over the N.C.T.D. tracks along Carlsbad Boulevard. Within Drainage Area A,
an increase of approximately 9,200 SF of impervious area is proposed. However, the
impervious area is attributed to the construction of the 10' wide Class I bike path and,
therefore, will not produce the pollutants associated with a roadway project (i.e. oils and
greases, heavy metals, and nutrients and pesticides (since no formal landscaping is proposed
within Drainage Area A). Within Drainage Area B, there is an overall decrease in impervious
area of approximately 2,000 SF. A majority of the improvements within this drainage area
will be constructed within the existing limits of pavement and therefore will not generate_any
new pollutants.
Proposed storm drain improvements include the installation of two curb inlets along State
Street, as well as the relocation of the existing headwall on the west side of the proposed
roundabout. A 36" square pre-cast inlet is proposed in the northbound approach median on
Carlsbad Boulevard.
3
Figure 2.1 Vicinity Map
(Reference Thomas Bros. 1106)
Storm Water Management Plan
Coastal Rail Trail-Reach 1
4
Storm Water Management Plan
Coastal Rail Trail-Reach 1
3 WATER QUALITY POLLUTANTS OF CONCERN
3.1 Potential Pollutants
The Coastal Rail Trail Reach 1 project falls in the "Streets, Highways, and Freeways"
category as highlighted in Table 3-1. Although many constituents are generally anticipated
for projects in this category the proposed project is not expected to generate significant
amounts of pollutants,
Table 3-1 Anticipated and Potential Pollutants Generated
./ Anticipated Pollutants
p Potential Pollutants General Pollutant Categories
00 Q)
(.) s:: ~ ..... 00 ..0 ::s en
00 bll -o s:: s::
Project Categories ::s .:;!l :.a 0 '"' ~ Q)
0.. ..0 00 00 e Q) e ~ ~ Cl Q)
0 Q) '"' ..... 0 00 Q) u -o Cl ..... 00 ~ s:: t= (.) ~ I -o Q) ·~ s:: s:: e Q) ;;.-.. Q) ·c > ..s:: bll ~ :.a 00 ~ .:!l ..... ~ bll ~ Q) ::s Q) '"' '"' 0 en z ::c: 0 f-< 0
Detached Residential ./ ./ ./ ./ ./
Attached Residential ./ ./ ./ p<l) p(2)
Commercial (> 100,000 sf) p(l) p(l) p(2) ./ p(5) ./
Heavy industry I industrial ./ ./ ./ ./ ./ ./
Auto Repair Shops ./ ./(4)(5) ./ ./
Restaurants ./ ./ ./
Hillside Development ./ ./ ./ ./ ./ 000
p(l) p(l) ./ ./ p(l) ./
(1) A potential pollutant if landscaping exists on-site;
(2) A potential pollutant if the project includes uncovered parking areas;
(3) A potential pollutant if land use involved food or animal waste products;
(4) Including petroleum hydrocarbons;
(5) Including solvents.
00 Q)
00 ::s '"' > -o s:: ~ 00
~ Q) ·c -o "() Q) ..... -~ (.) ~ Q) c:o ~
./ ./
p ./
p(3) p(5)
./
5
Storm Water Management Plan
Coastal Rail Trail-Reach 1
As indicated in Section 2.1, the project consists of narrowing the existing roadway and
constructing a roundabout, bike lanes, a bike route and sidewalks that will facilitate bicycle
and pedestrian traffic. Potential pollutants of concern associated with this project category
include:
Drainage Area A:
• Sediments (since the trail will be constructed adjacent to existing landscaped areas);
• Organic Compounds (since dog walking is possible);
• Litter and trash collecting in the drainage systems;
• Oxygen-demanding substances including biodegradable organic material and
chemicals;
Drainage Area B:
• Sediments (since there will be landscaped areas on site);
• Nutrients (since there will be landscaped areas on site);
• Heavy Metals (limited to occasional maintenance trucks);
• Organic Compounds (since dog walking is possible);
• Litter and trash collecting in the drainage systems;
• Oxygen-demanding substances including biodegradable organic material and
chemicals;
• Pesticides used to control nuisance landscape growth;
• Oils, grease, and other hydrocarbons emanating from paved areas on the site.
As noted in Section 1, this project is not a "Priority Project" and is required to meet the
'Standard Stormwater Requirements' only. Therefore, no calculable level of treatment is
required for the Coastal Rail Trail -Reach 1 project.
Additionally, the anticipated pollutants listed for Drainage Area Bare already being generated
by the existing roadway. The proposed project does not generate any new pollutants of
concern.
3.1.1 Sediment
Sediments are soils or other surface materials eroded and then transported or deposited by the
action of wind, water, ice, or gravity. Sediments can increase turbidity, clog fish gills, reduce
spawning habitat, lower young aquatic organisms survival rates, smother bottom dwelling
organisms, and suppress aquatic vegetation growth.
3.1.2 Nutrients
Nutrients are inorganic substances, such as nitrogen and phosphorus. They commonly exist in
the form of mineral salts that are either dissolved or suspended in water. Primary sources of
nutrients in urban runoff are fertilizers and eroded soils. Excessive discharge of nutrients to
water bodies and streams can cause excessive aquatic algae and plant growth. Such excessive
production, referred to as cultural eutrophication, may lead to excessive decay of organic
matter in the water body, loss of oxygen in the water, release of toxins in sediment, and the
eventual death of aquatic organisms.
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3.1.3 Metals
Storm Water Management Plan
Coastal Rail Trail-Reach 1
Metals are raw material components in non-metal products such as fuels, adhesives, paints,
and other coatings. The primary sources of metal pollution in storm water are typically
commercially available metals and metal products. Metals of concern include cadmium,
chromium, copper, lead, mercury, and zinc. Lead and chromium have been used as corrosion
inhibitors in primer coatings and cooling tower systems. At low concentrations naturally
occurring in soil, metals are not toxic. However, at higher concentrations, certain metals can
be toxic to aquatic life. Humans can be impacted from contaminated groundwater resources,
and bioaccumulation of metals in fish and shellfish. Environmental concerns, regarding the
potential for release of metals to the environment, have already led to restricted metal usage in
certain applications.
3.1.4 Organic Compounds
Organic compounds are carbon-based (commercially available or naturally occurring)
substances found in pesticides, solvents, and hydrocarbons. Organic compounds can, at
certain concentrations, indirectly or directly constitute a hazard to life or health. When rinsing
off objects, toxic levels of solvents and cleaning compounds can be discharged to storm
drains. Dirt, grease, and grime retained in the cleaning fluid or rinse water may also adsorb
levels of organic compounds that are harmful or hazardous to aquatic life.
3.1.5 Trash and Debris
Trash (such as paper, plastic, polystyrene packing foam, and aluminum materials) and
biodegradable organic matter (such as leaves, grass cuttings, and food waste) are general
waste products on the landscape. The presence of trash and debris may have a significant
impact on the recreational value of a water body and aquatic habitat. Excess organic matter
can create a high biochemical oxygen demand in a stream and thereby lower its water quality.
Also, in areas where stagnant water exists, the presence of excess organic matter can promote
septic conditions resulting in the growth of undesirable organisms and the release of odorous
and hazardous compounds such as hydrogen sulfide.
3.1.6 Oxygen-demanding Substances
This category includes biodegradable organic material as well as chemicals that react with
dissolved oxygen in water to form other compounds. Proteins, carbohydrates, and fats are
examples of biodegradable organic compounds. Compounds such as ammonia and hydrogen
sulfide are examples of oxygen-demanding compounds. The oxygen demand of a substance
can lead to depletion of dissolved oxygen in a water body and possibly the development of
septic conditions.
3.1.7 Pesticides
Pesticides (including herbicides) are chemical compounds commonly used to control nuisance
growth of organisms. Excessive application of a pesticide may result in runoff containing
toxic levels of its active component.
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3.1.8 Oil and Grease
Storm Water Management Plan
Coastal Rail Trail-Reach 1
Oil and grease are characterized as high-molecular weight organic compounds. The primary
sources of oil and grease are petroleum hydrocarbon products, motor products from leaking
vehicles, esters, oils, fats, waxes, and high molecular-weight fatty acids. Introduction ofthese
pollutants to the water bodies are very possible due to the wide uses and applications of some
of these products in municipal, residential, commercial, industrial, and construction areas.
Elevated oil and grease content can decrease the aesthetic value of the water body, as well as
the water quality.
3.2 Primary Pollutants of Concern
The Environmental Protection Agency (EPA) is the primary federal agency responsible for
management of water quality in the United States. The Clean Water Act (CWA) is the
federal law that governs water quality control activities initiated by the EPA and others.
Section 303 ofthe CWA requires the adoption ofwater quality standards for all surface water
in the United States. Under Section 303(d), individual states are required to develop lists of
water bodies that do not meet water quality objectives after required levels of treatment by
point source dischargers. Total maximum daily loads (TMDLs) for all pollutants for which
these water bodies are listed must be developed in order to bring them into compliance with
water quality objectives.
The project site is located in the 14,437-acre (22.6 square mile) Buena Vista Creek
Hydrologic Area (HA 904.2), which is part of the Carlsbad Hydrologic Unit (HU 904.00).
The most immediate receiving waters for the project site are the Buena Vista Lagoon and the
Pacific Ocean. According to the California 2006 303(d) list published by the San Diego
Regional Water Quality Control Board (RWQCB Region 9), Buena Vista Lagoon is impaired
by bacteria indicators, nutrients and sedimentation. The Pacific Shoreline, located
approximately half a mile downstream, is listed as impaired by bacteria indicator. Refer to
Table 3-2 for the impairments of the downstream waterbodies. It is highly unlikely that the
potential pollutants from the project site would have a significant detrimental effect on the
listed impairments downstream, but the impairments should be kept in mind when
determining the appropriate program of BMPs. Table 3-2 summarizes the receiving waters
and their classification by the RWQCB Region 9.
Table 3-2 Summary of Receiving Surface Waters
Receiving Water
Buena Vista Lagoon
Pacific Ocean Shoreline (Buena Vista Creek)
Hydrologic
Unit Code
904.21
904.21
Approximate
Distance From
Site
Omi
0.5mi
303(d)
lmpairment(s)
Sedimentation,
Bacteria Indicators,
Nutrients
Bacteria Indicators
Receiving waters downstream of the project site are impaired by bacteria indicators, nutrients,
and sedimentation as shown in Table 3-2. The proposed project activities are anticipated to
produce sediment, nutrients, metals (limited), organic compounds, trash debris, pesticides and
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Storm Water Management Plan
Coastal Rail Trail-Reach 1
oil and grease, as shown in Table 3-1. Therefore, the primary pollutants of concern associated
with the project are nutrients, and sediment. The remaining anticipated pollutants are
considered secondary pollutants of concern.
9
Storm Water Management Plan
Coastal Rail Trail-Reach 1
4 WATER QUALITY CONDITIONS OF CONCERN
According to the City of Carlsbad SUSMP, a change to a priority project site's hydrologic
regime would be considered a condition of concern if the change would negatively impact
downstream channels and habitat integrity. However, the hydrologic regime described here
will not be negatively impacted with the proposed project. The existing condition of the
Reach 1 Corridor is a paved roadway and is mostly impervious. The proposed plan adds new
impervious area, with comparable runoffvalues.
A drainage report has been prepared for this project and it has been determined that the
existing storm drain system will not be adversely impacted by the revised layout. The
integrity of downstream channels and existing habitats will also be maintained. Since runoff
from the project discharges into new and existing drainage facilities that are verified and/or
designed to accommodate peak runoff flow rates from a 1 00-year storm event, there are no
conditions of concern associated with the project.
The Federal Insurance Rate Map (FIRM) (Panel 761 of 2375) for this area shows that the
project's location is not within of the 1 00-year floodplain.
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Storm Water Management Plan
Coastal Rail Trail-Reach 1
5 STANDARD STORMWATER REQUIREMENTS
Standard Stormwater Requirements involve incorporating the following applicable techniques
into the project design:
5.1 Minimize Impervious Surfaces
Using excessive impervious surfaces tend to increase the potential of pollutant contact with
urban runoff and increase runoff. The overall project decreases the area of pollutant-
generating impervious surfaces. Additionally, the construction of a roundabout will improve
traffic flow, as well as cut down vehicular emissions and fuel consumption by reducing the
vehicle idle time (opportunity for oils and greases to drip) at intersections, thereby creating an
overall positive impact on the environment.
5.2 Disconnect Impervious Discharges
Using vegetated areas in the landscape design to intercept and filter runoff is an encouraged
approach. Within Drainage Area B, the project proposes the use of vegetated strips, as
described in the following section. Additionally, runoff generated from the 10' wide bike
path within Drainage Area A will be directed to the natural vegetated area adjacent to the
proposed improvements, providing an opportunity for filtration and infiltration prior to
discharging to the Buena Vista Lagoon.
5.3 Conserve Natural Areas
The majority ofthe project footprint is to be constructed within the existing limits of roadway,
therefore preserving and protecting the natural features directly adjacent to the project. No
constructed improvements are proposed between the proposed roundabout and Oak A venue.
5.4 Stenciling Inlets and Signage
All new storm drain grate inlets constructed as part of this project will be signed with the
message ''No Dumping-I live downstream" or equivalent message, as directed by the City.
The project also proposes signs with descriptive language prohibiting dumping into the Buena
Vista Lagoon.
5.5 Landscape Design
Efficient landscape design can be an effective source-control to prevent pollution in storm
water and dry-weather flows. Within Drainage Area B, the completed project will incorporate
native plants and implement principles of runoff-minimizing landscape design and an
effective landscape maintenance plan to the maximum extent practicable. No new
landscaping is proposed within Drainage Area A.
5. 6 Water Efficient Landscaping
Landscape designs that group plants with similar water requirements can reduce excess
irrigation runoff and promote surface infiltration. Within Drainage Area A, the landscape
design will utilize non-invasive native plant species and drought tolerant plants. No new
landscaping (including irrigation) is proposed within Drainage Area A.
11
5. 7 Protect Slopes and Channels
Storm Water Management Plan
Coastal Rail Trail-Reach 1
As mentioned previously, the majority of the project footprint is to be constructed within the
existing limits of roadway, therefore preserving and protecting the natural features directly
adjacent to the project. The proposed vegetated strip will act as a buffer area and aid in safely
conveying runoffto adjacent drainage course.
5.8 Trash Receptacles
Trash storage areas shall be paved with an impervious surface, designed not to allow run-on
from adjoining areas, and have attached lids to prevent off-site transport of trash and rain
from entering the container.
5.9 Material Storage Areas
No material storage will take place at the proposed project site.
5.10 Vegetated Buffer Strip
Although, the construction of treatment control BMPs are not required, vegetated strips will
be constructed within Drainage Area B, along Carlsbad Boulevard between the existing
bridge and the proposed roundabout. Vegetated strips are vegetated surfaces that are designed
to treat sheet flow from adjacent surfaces. Strips function by slowing runoff velocities and
allowing sediment and other pollutants to settle and by providing some infiltration into
underlying soils. The Drainage Area B runoff flows north and west and will enter the strips
onsite. Flow then travels slowly north-west through the natural vegetated area before being
discharged into the Buena Vista Lagoon.
5.11 Drain Inserts
To provide additional treatment and removal of potential pollutants, drainage inlet inserts will
be installed in all storm drain inlets. Bio-Clean Environmental® round curb inlet baskets (or
approved equal) will be specified to treat runoff for hydrocarbons and trash/debris. Surface
runoff enters the inlet and passes over/through an adsorbent material to remove hydrocarbons,
while sediments and trash/debris are collected in the hanging basket.
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6 BMP MAINTENANCE PROVISIONS
Storm Water Management Plan
Coastal Rail Trail-Reach 1
To ensure long-term maintenance of project BMPs, the City of Carlsbad will maintain, repair
and replace the storm water BMP as necessary into perpetuity.
The site shall be kept in a neat and orderly fashion with a regularly scheduled landscape
maintenance crew in charge of keeping gutters and inlets free of litter and debris. The
landscape crew will also maintain the landscaping to prevent soil erosion and minimize
sediment transport.
Maintenance records shall be retained for at least 5-years.
6.1 Landscape Maintenance
The landscape maintenance plan should include a regular sweeping program of impervious
surfaces, litter pick-up, and proper equipment maintenance (preferably off-site), and proper
use of chemicals to help eliminate sources of storm water pollutants. Common elements of an
effective landscape maintenance plan include:
• A regularly rotating schedule of maintenance ensures the property is in a perpetual
state of good cleanliness. Maintenance obligations include regular sweeping of
sidewalks, driveways, and gutters, and staff members' job duties include perpetual
litter pick-up. The City will provide convenient trash receptacles for public use
located throughout the trail.
• Avoid using water to clean sidewalks, driveways, and other areas.
• All landscape maintenance equipment is cleaned off-site. Minimize water use and do
not use soaps or chemicals.
• Keep all landscape equipment in good working order. Fix all leaks promptly, and use
drip pans/drip cloths when draining and replacing fluids. Perform all repairs and
equipment maintenance offsite. Protect all nearby storm water inlets. Keep regular
logs of major equipment repairs. All spent fluids are to be collected and disposed of
properly.
• Materials with the potential to pollute runoff (soil, pesticides, herbicides, fertilizers,
detergents, petroleum products, and other materials) are handled, delivered, applied,
and disposed of with care following manufacturer's labeled directions and in
accordance with all applicable Federal, state, and local regulations. Volatile chemicals
are stored and locked in isolated storage sheds with paved flooring.
• Pesticides and fertilizers, if used, will be applied according to manufacturer's
directions and will not be applied prior to a forecast rain event. Any material
broadcast onto paved surfaces (e.g. parking areas or sidewalks) will be promptly swept
up and properly disposed.
6.2 Vegetated Buffer Strip Maintenance
Usually, strips require little more than normal landscape maintenance activities such as
irrigation and mowing to maintain pollutant removal efficiency. Strips can become a nuisance
due to mosquito breeding in standing water if obstructions develop (i.e. debris accumulation,
13
Storm Water Management Plan
Coastal Rail Trail-Reach 1
invasive vegetation) and/or if proper drainage slopes are not implemented and maintained.
The application of fertilizers and pesticides should be minimized.
6.3 Drain Inserts Maintenance
Recommended maintenance consists oftwo to four inspections per year (depending on street
traffic and sediment load) plus replacement of the adsorbent when it is more than 50% coated
with pollutants and removal of excessive sediment/debris. Each inlet insert costs about $845-
$1,000 and is available locally through Bio-Clean Environmental Services (760-433-7640).
The inserts can be installed by Bio-Clean Environmental Services for additional cost or by the
project construction contractor. Maintenance costs are estimated at about $79-$110 per
cleaning.
14
Appendix A -Storm Water Standards Questionnaire
"~'~'\ ''· ~~:-~ CITY OF
CARLSBAD
STORM WATER
STANDARDS
QUESTIONNAIRE
E-34
INSTRUCTIONS: If you answered YES, you ARE a significant redevelopment, you
Development Services
Land Development Engineering
1635 Faraday Avenue
760-602-2750
www.carlsbadca.gov
X
X
PROJECT requirements. Please check the "meets PRIORITY DEVELOPMENT PROJECT requirements" box in Section 3 below. Review
SUSMP to find out if SUSMP requirements apply to your project envelope or the entire project site.
If you answered NO, then you ARE NOT a significant redevelopment and your project is subject to STANDARD STORMWATER
REQUIREMENTS. Please check the "does not meet PDP requirements" box in Section 3 below.
4 on page 2
D My project meets PRIORITY DEVELOPMENT PROJECT (PDP) requirements and must comply with additional stormwater criteria
per the SUSMP and I understand I must prepare a Storm Water Management Plan for submittal at time of application. I understand
flow control (hydromodification) requirements may apply to my project. Refer to SUSMP for details.
~ My project does not meet PDP requirements and must only comply with STANDARD STORMWATER REQUIREMENTS per the
SUSMP. As of these I will low
Applicant Information and Signature Box This Box for City Use Only
Address: Assessor's Parcel Number(s): City Concurrence: I YES I NO
I I
Applicant Name: Applicant Title: By:
Date:
Applicant Signature: Date: Project ID:
E-34 Page 3 of3 REV 1114111
Appendix B-BMP Fact Sheets
Vegetated Buffer Strip
Description
Grassed buffer strips (vegetated filter strips, filter strips, and
grassed filters) are vegetated surfaces that are designed to treat
sheet flow from adjacent surlaces. Filter strips function by
slowing runoff velocities and allowing sediment and other
pollutants to settle and by providing some infiltration into
underlying soils. Filter strips were originally used as an
agricultural treatment practice and have more recently evolved
into an urban practice. With proper design and maintenance,
filter strips can provide relatively high pollutant removal. In
addition, the public views them as landscaped amenities and not
as stormwater infrastructure. Consequently, there is little
resistance to their use.
~alifornia Experience
Caltrans constructed and monitored three vegetated buffer strips
in southern California and is currently evaluating their
perlormance at eight additional sites statewide. These strips were
generally effective in reducing the volume and mass of pollutants
in runoff. Even in the areas where the annual rainfall was only
about 10 inchesjyr, the vegetation did not require additional
irrigation. One factor that strongly affected perlormance was the
presence of large numbers of gophers at most of the southern
California sites. The gophers created earthen mounds, destroyed ·
vegetation, and generally reduced the effectiveness of the
controls for TSS reduction.
Advantages
• Buffers require minimal maintenance activity (generally just
erosion prevention and mowing).
• If properly designed, vegetated, and operated, buffer strips can
provide reliable water quality benefits in conjunction with
high aesthetic appeal.
January 2003 California Stormwater BMP Handbook
New Development and Redevelopment
www.cabmphandbooks.com
TC-31
Design Considerations
• Tributary Area
• Slope
• Water Availability
• Aesthetics
Targeted Constituents
~ Sediment • ~ Nutrients • ~ Trash ...
~ Metals • ~ Bacteria • ~ Oil and Grease • ~ Organics ...
legend (Removal Etrectlveness}
• Low • High
.&. Medium
1 of8
TC-31 Vegetated Buffer Strip
• Flow characteristics and vegetation type and density can be closely controlled to maximize
BMP effectiveness.
• Roadside shoulders act as effective buffer strips when slope and length meet criteria
described below.
Limitations
• May not be appropriate for industrial sites or locations where spills may occur.
• Buffer strips cannot treat a very large drainage area.
• A thick vegetative cover is needed for these practices to function properly.
• Buffer or vegetative filter length must be adequate and flow characteristics acceptable or
water quality performance can be severely limited.
• Vegetative buffers may not provide treatment for dissolved constituents except to the extent
that flows across the vegetated surface are infiltrated into the soil profile.
• This technology does not provide significant attenuation of the increased volume and flow
rate of runoff during intense rain events.
Design and Sizing Guidelines
• Maxinmm length (in the direction of flow towards the buffer) of the tributary area should be
6o feet.
• Slopes should not exceed 15%.
• Minimum length (in direction of flow) is 15 feet.
• Width should be the same as the tributary area.
• Either grass or a diverse selection of other low growing, drought tolerant, native vegetation
should be specified. Vegetation whose growing season corresponds to the wet season is
preferred.
Construction/Inspection Considerations
• Include directions in the specifications for use of appropriate fertilizer and soil amendments
based on soil properties determined through testing and compared to the needs of the
vegetation requirements.
• Install strips at the time of the year when there is a reasonable chance of successful
establishment without irrigation; however, it is recognized that rainfall in a given year may
not be sufficient and temporary irrigation may be required.
• If sod tiles must be used, they should be placed so that there are no gaps between the tiles;
stagger the ends of the tiles to prevent the formation of channels along the strip.
• Use a roller on the sod to ensure that no air pockets form between the sod and the soil.
2of8 California Stormwater BMP Handbook
New Development and Redevelopment
www.cabmphandbooks.com
January 2003
Vegetated Buffer Strip TC-31
• Where seeds are used, erosion controls will be necessary to protect seeds for at least 75 days
after the first rainfall of the season.
Performance
Vegetated buffer strips tend to provide somewhat better treatment of stormwater runoff than
swales and have fewer tendencies for channelization or erosion. Table 1 documents the pollutant
removal observed in a recent study by Caltrans (2002) based on three sites in southern
California. The column labeled "Significance" is the probability that the mean influent and
effluent EMCs are not significantly different based on an analysis of variance.
The removal of sediment and dissolved metals was comparable to that observed in much more
complex controls. Reduction in nitrogen was not significant and all of the sites exported
phosphorus for the entire study period. Tiri.s may have been the result of using salt grass, a warm
weather species that is dormant during the wet season, and which leaches phosphorus when
dormant.
Another Cal trans study (unpublished) of vegetated highway shoulders as buffer strips also found
substantial reductions often within a very short distance of the edge of pavement. Figure 1
presents a box and whisker plot of the concentrations ofTSS in highway runoff after traveling
various distances (shown in meters) through a vegetated filter strip with a slope of about 10%.
One can see that the TSS median concentration reaches an irreducible minimum concentration
of about 20 mg/L within 5 meters of the pavement edge.
Table 1 Pollutant Reduction in a Vegetated Buffer Strip
Constituent
TSS
NOs-N
TKN-N
TotalNI
DissolvedP
TotalP
TotalCu
Total Ph
TotalZn
Dissolved Cu
Dissolved Pb
Dissolved Zn
January 2003
MeanEMC
Removal
Influent Emuent %
(mg/L) (mg/L)
119 31 74
0.67 o.ss 13
2-50 2.10 16
3-17 2.68 15
0.15 0.46 -206
0.42 0.62 -52
o.osS 0.009 84
0.046 o.oo6 88
0.245 o.oss 78
0.029 0.007 77
0.004 0.002 66
0.09') 0-035 65
California Stormwater BMP Handbook
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Significance
p
<0.000
0.367
0.542
0.047
0.035
<0.000
<0.000
<0.000
0.004
o.oo6
<0.000
3of8
TC-31 Vegetated Buffer Strip
100
90
so
70 * * +-' 60 ::J 0
(J)I 50 * (J) 40 * t-
30 ~ 20 8 10
0
length 0 ""': <'! <'! ~ ci ...,. co (0
Filter strips also exhibit good removal of litter and other floatables because the water depth in
these systems is well below the vegetation height and consequently these materials are not easily
transported through them. Unfortunately little attenuation of peak runoff rates and volumes
(particularly for larger events) is normally observed, depending on the soil properties. Therefore
it may be prudent to follow the strips with another practice than can reduce flooding and
channel erosion downstream.
Siting Criteria
The use of buffer strips is limited to gently sloping areas where the vegetative cover is robust and
diffuse, and where shallow flow characteristics are possible. The practical water quality benefits
can be effectively eliminated with the occurrence of significant erosion or when flow
concentration occurs across the vegetated surface. Slopes should not exceed 15 percent or be less
than 1 percent. The vegetative surface should extend across the full width of the area being
drained. The upstream boundary of the filter should be located contiguous to the developed
area. Use of a level spreading device (vegetated berm, sawtooth concrete border, rock trench,
etc) to facilitate overland sheet flow is not normally recommended because of maintenance
considerations and the potential for standing water.
Filter strips are applicable in most regions, but are restricted in some situations because they
consume a large amount of space relative to other practices. Filter strips are best suited to
treating runoff from roads and highways, roof downspouts, small parking lots, and pervious
surfaces. They are also ideal components of the "outer zone" of a stream buffer or as
pretreatment to a structural practice. In arid areas, however, the cost of irrigating the grass on
the practice will most likely outweigh its water quality benefits, although aesthetic
considerations may be sufficient to overcome this constraint. Filter strips are generally
impractical in ultra-urban areas where little pervious surface exists.
Some cold water species, such as trout, are sensitive to changes in temperature. While some
treatment practices, such as wet ponds, can warm stormwater substantially, filter strips do not
4of8 California Stormwater BMP Handbook
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January 2003
Vegetated Buffer Strip TC-31
are not expected to increase stormwater temperatures. Thus, these practices are good for
protection of cold-water streams.
Filter strips should be separated from the ground water by between 2 and 4ft to prevent
contamination and to ensure that the filter strip does not remain wet between storms.
Additional Design Guidelines
Filter strips appear to be a minimal design practice because they are basically no more than a
grassed slope. In general the slope of the strip should not exceed tsfc% and the strip should be
at least 15 feet long to provide water quality treatment. Both the top and toe of the slope should
be as flat as possible to encourage sheet flow and prevent erosion. The top of the strip should be
installed 2-5 inches below the adjacent pavement, so that vegetation and sediment accumulation
at the edge of the strip does not prevent runoff from entering.
A major question that remains unresolved is how large the drainage area to a strip can be.
Research has conclusively demonstrated that these are effective on roadside shoulders, where
the contributing area is about twice the buffer area. They have also been installed on the
perimeter of large parking lots where they perlormed fairly effectively; however much lower
slopes may be needed to provide adequate water quality treatment.
The filter area should be densely vegetated with a mix of erosion-resistant plant species that
effectively bind the soil. Native or adapted grasses, shrubs, and trees are preferred because they
generally require less fertilizer and are more drought resistant than exotic plants. Runoff flow
velocities should not exceed about 1 fps across the vegetated surlace.
For engineered vegetative strips, the facility surlace should be graded flat prior to placement of
vegetation. Initial establishment of vegetation requires attentive care including appropriate
watering, fertilization, and prevention of excessive flow across the facility until vegetation
completely covers the area and is well established. Use of a permanent irrigation system may
help provide maximal water quality perlormance.
In cold climates, filter strips provide a convenient area for snow storage and treatment. If used
for this purpose, vegetation in the filter strip should be salt-tolerant (e.g., creeping bentgrass),
and a maintenance schedule should include the removal of sand built up at the bottom of the
slope. In arid or semi-arid climates, designers should specify drought-tolerant grasses to
minimize irrigation requirements.
Maintenance
Filter strips require mainly vegetation management; therefore little special training is needed
for maintenance crews. Typical maintenance activities and frequencies include:
• Inspect strips at least twice annually for erosion or damage to vegetation, preferably at the
end of the wet season to schedule summer maintenance and before major fall run-off to be
sure the ~p is ready for winter. However, additional inspection after periods of heavy run-
off is most desirable. The strip should be checked for debris and litter and areas of sediment
accumulation.
• Recent research on biofiltration swales, but likely applicable to strips {Colwell et al., 2000 ),
indicates that grass height and mowing frequency have little impact on pollutant removal;
January 2003 california Stormwater BMP Handbook
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. .
TC-31 Vegetated Buffer Strip
consequently, mowing may only be necessary once or twice a year for safety and aesthetics
or to suppress weeds and woody vegetation.
• Trash tends to accumulate in strip areas, particularly along highways. The need for litter
removal should be determined through periodic inspection but litter should always be
removed prior to mowing.
• Regularly inspect vegetated buffer strips for pools of standing water. Vegetated buffer strips
can become a nuisance due to mosquito breeding in level spreaders (unless designed to
dewater completely in 48-72 hours), in pools of standing water if obstructions develop (e.g.
debris accumulation, invasive vegetation), and/or if proper drainage slopes are not
implemented and maintained.
Cost
Construction Cost
Little data is available on the actual construction costs of filter strips. One rough estimate can be
the cost of seed or sod, which is approximately 30¢ per ft2 for seed or 70¢ per ft2 for sod. This
amounts to between $13,000 and $30,000 per acre of filter strip. This cost is relatively high
compared with other treatment practices. However, the grassed area used as a filter strip may
have been seeded or sodded even if it were not used for treatment. In these cases, the only
additional cost is the design. Typical maintenance costs are about $350/acrejyear (adapted
from SWRPC, 1991). This cost is relatively inexpensive and, again, might overlap with regular
landscape maintenance costs.
The true cost of filter strips is the land they consume. In some situations this land is available as
wasted space beyond back yards or adjacent to roadsides, but this practice is cost-prohibitive
when land prices are high and land could be used for other purposes.
Maintenance Cost
Maintenance of vegetated buffer strips consists mainly of vegetation management (mowing,
irrigation if needed, weeding) and litter removal. Consequently the costs are quite variable
depending on the frequency of these activities and the local labor rate.
References and Sources of Additional Information
Caltrans, 2002, BMP Retrofit Pilot Program Proposed Final Report, Rpt. CTSW-RT-m-oso,
California Dept. of Transportation, Sacramento, CA.
Center for Watershed Protection (CWP). 1996. Design of Stormwater Filtering Systems.
Prepared fot Chesapeake Research Consortium, Solomons, MD, and EPA Region V, Chicago, IL.
Desbonette, A., P. Pogue, V. Lee, and N. Wolff. 1994-Vegetated Buffers in the Coastal Zone: A
Summary Review and Bibliography. Coastal Resources Center. University of Rhode Island,
Kingston, Rl
Magette, W., R Brinsfield, R. Palmer andJ. Wood. 1989. Nutrient and Sediment Removal by
Vegetated Filter Strips. Transactions of the American Society of Agricultural Engineers 32(2):
663-667.
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January 2003
Vegetated Buffer Strip TC-31
Metzger, M. E., D. F. Messer, C~ L. Beitia, C. M. Myers, and V. L. Kramer. 2002. The Dark Side
Of Stonnwater Runoff Management: Disease Vectors Associated With Structural BMPs.
Stonnwater 3(2): 24-39.
Southeastern WlSconsin Regional Planning Commission (SWRPC). 1991. Costs of Urban
Nonpoint Source Water Pollution Control Measures. Technical report no. 31. Southeastern
Wisconsin Regional Planning Commission, Waukesha, Wl
Yu, S., S. Barnes and V. Gerde. 1993-Testing of Best Management Practices for Controlling
Highway Runoff FHWA/VA93-R16. Virginia Transportation Research CounCil,
Charlottesville, VA
Iriformation Resources
Center for Watershed Protection (CWP). 1997. Stormwater BMP Design Supplement/or Cold
Climates. Prepared for U.S. Environmental Protection Agency Office of Wetlands, Oceans and
Watersheds. Washington, DC.
Maryland Department of the Environment (MDE). 2000. Maryland Stormwater Design
Manual. http://www.mde.state.md.us/environment/wm.a/stormwatermanuaL Accessed May
22,2001.
January 2003 California Stormwater BMP Handbook
New Development and Redevelopment
www.cabmphandbooks.com
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TC-31
Pavcme:at ANa
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Vegetated Buffer Strip
-i: * * .. i -.
* * ..
.. PikllrStdp ..
* -* i •
Note: Not to Scale
callfurnJa Stormwater BMP Handbook
New Development and Redevelopment
www.cabmphandbooks.com
January 2003
Drain Inserts
Description
Drain inserts are manufactured filters or fabric placed in a drop
inlet to remove sediment and debris. There are a multitude of
inserts of various shapes and configurations, typically falling into
one of three different groups: socks, boxes, and trays. The sock
consists of a fabric, usually constructed of polypropylene. The
fabric may be attached to a frame or the grate of the inlet holds
the sock. Socks are meant for vertical (drop) inlets. Boxes are
constructed of plastic or wire mesh. Typically a polypropylene
"bag" is placed in the wire mesh box. The bag takes the form of
the box. Most box products are one box; that is, the setting area
and filtration through media occur in the same box. Some
products consist of one or more trays or mesh grates. The trays
may hold different types of media. Filtration media vacy by
manufacturer. Types include polypropylene, porous polymer,
treated cellulose, and activated carbon.
California Experience
The number of installations is unknown but likely exceeds a
thousand. Some users have reported that these systems require
considerable maintenance to prevent plugging and bypass.
Advantages
• Does not require additional space as inserts as the drain
inlets are already a component of the standard drainage
systems.
• Easy access for inspection and maintenance.
• As there is no standing water, there is little concern for
mosquito breeding.
• A relatively inexpensive retrofit option.
Limitations
Performance is likely significantly less than treatment systems
that are located at the end of the drainage system such as ponds
and vaults. Usually not suitable for large areas or areas with
trash or leaves than can plug the insert.
Design and Sizing Guidelines
Refer to manufacturer's guidelines. Drain inserts come any
many configurations but can be placed into three general groups:
socks, boxes,. and trays. The sOck consists of a fabric, usually
constructed of polypropylene. The fabric may be attached to a
frame or the grate of the inlet holds the sock. Socks are meant
for vertical (drop) inlets. Boxes are constructed of plastic or wire
mesh. Typically a polypropylene "bag" is placed in the wire mesh
box. The bag takes the form of the box. Most box products are
January 2003 California Stormwater BMP Handbook
New Development and Redevelopment
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MP-52
Design Considerations
• Use with other BMPs
• Fit and Seal Capacity within Inlet
Targeted Constituents
~ Sediment
~ Nutrients
~ Trash
~ Metals
Bacteria
~ Oil and Grease
~ Organics
Removal El'fecfiveneH
See New Development and
Redevelopment Handbook-Section 5.
MP-52 Drain Inserts
one box; that is, the setting area and filtration through media occurs in the same box. One
manufacturer has a double-box. Stormwater enters the first box where setting occurs. The
stormwater flows into the second box where the filter media is located. Some products consist
of one or more trays or mesh grates. The trays can bold different types of media. Filtration
media vary with the manufacturer: types include polypropylene, porous polymer, treated
cellulose, and activated carbon.
Constructionjlnspection Considerations
Be certain that installation is done in a manner that makes certain that the stormwater enters
the unit and does not leak around the perimeter. Leakage between the frame of the insert and
the frame of the drain inlet can easily occur with vertical (drop) inlets.
Performance
Few products have perfom1ance data collected under field conditions.
Siting Criteria
It is recommended that inserts be used only for retrofit situations or as pretreatment where
other treatment BMPs presented in this section area used.
Additional Design Guidelines
Follow guidelines provided by individual manufacturers.
Maintenance
Likely require frequent maintenance, on the order of several times per year.
Cost
• The initial cost of individual inserts ranges from less than $100 to about $2,000. The cost of
using multiple units in curb inlet drains varies with the size of the inlet.
• The low cost of inserts may tend to favor the use of these systems over other, more effective
treatment BMPs. However, the low cost of each unit may be offset by the number of units
that are required, more frequent maintenance, and the shorter structural life (and therefore
replacement).
References and Sources of Additional Information
Hrachovec, R., and G. Minton, 2001, Field testing of a sock-type catch basin insert, Planet CPR,
Seattle,~ashington
Interagency Catch Basin Insert Committee, Evaluation of Commercially-Available Catch Basin
Inserts for the Treatment ofStormwater Runoff from Developed Sites, 1995
Larry Walker Associates, June 1998, NDMP Inlet/In-Line Control Measure Study Report
Manufacturers literature
Santa Monica (City), Santa Monica Bay Municipal Stormwater/Urban Runoff Project-
Evaluation of Potential Catch basin Retrofits, ~oodward Clyde, September 24, 1998
2of3 California Stormwater BMP Handbook
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January 2003
Drain Inserts MP-52
Woodward Clyde, June 11~ 1996, Parking Lot Monitoring Report, Santa Clara Valley Nonpoint
Source Pollution Control Program.
January 2003 California Stormwater BMP Handbook
New Development and Redevelopment
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3of3
Appendix C-BMP Site Plan
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