City
of San José, California
DRAFT CITY COUNCIL POLICY
| TITLE
|
PAGE 1 of 10 |
POLICY NUMBER 6-29 |
| POST-CONSTRUCTION URBAN RUNOFF MANAGEMENT |
EFFECTIVE DATE February 3, 1998 |
REVISED DATE 9/30/2003 |
| APPROVED BY COUNCIL ACTION February 3, 1998, Item 9d.; September
30, 2003 |
||
The Federal Clean Water Act requires
local municipalities to implement measures to control pollution
from their storm sewer systems to the maximum extent practicable.
Under the auspices of the Clean Water Act, as well as other
Federal and State legislation since 1990, the San Francisco
Regional Water Quality Control Board (RWQCB) has issued and
reissued an area-wide National Pollutant Discharge Elimination
System (NPDES MS4) Permit to the fifteen Co-permittees of
the Santa Clara Valley Urban Runoff Pollution Prevention Program
(SCVURPPP) for the discharge of storm water from urban areas
in Santa Clara County. The fifteen SCVURPPP Co-permittees
are the City of San Jose, twelve other municipalities within
the Santa Clara Basin watershed area, the County of Santa
Clara, and the Santa Clara Valley Water District.
Under
the provisions of the SCVURPPP Permit, each of the co-permittees,
including the City of San Jose, is required to implement control
measures/best management practices (BMPs) to reduce storm
water pollution from new development or redevelopment projects
to the maximum extent practicable. In October 2001, SCVURPPP
Permit Provision C.3 (New and Redevelopment Performance Standards)
was revised to require that certain types of new and redevelopment
projects include storm water runoff treatment control measures;
that the treatment measures be designed to treat a specified
volume or flow of storm water runoff from the project site;
and that the measures be maintained for the life of the project.
It
is the purpose of this policy to establish an implementation
framework, consistent with current SCVURPPP NPDES MS4 Permit
requirements, for incorporating storm water runoff pollution
control measures into new development and redevelopment projects
to reduce storm water runoff pollution from new development
and redevelopment projects to the maximum extent practicable.
Brownfields
Project: A project located on abandoned, idle,
or under-utilized property where expansion or redevelopment
is complicated by real or perceived environmental contamination.
Expansion
Projects: Projects involving a Land Use of Concern
(see below) and proposing expansion of fifty percent (50%)
or more of the previously existing built development, site
area, or use. An Expansion Project may also include a change
of use on an existing site when no new buildings or pavement
are proposed if that change results in the potential for increases
in the deposition of Pollutants of Concern
on the site. New uses that require an increase in on-site
surface parking or result in an increase in on-site vehicular
traffic would meet this criterion. Changes of use to any of
the major Land Uses of Concern described in this Policy may
also be considered an Expansion Project. A Major Expansion
is an Expansion Project that creates one acre (43,560 square
feet) or more of impervious surface area.
Impervious
Surface: Any surface
on or above ground that prevents the infiltration or passage
of water into the soil. Impervious surfaces include, but are
not limited to, non-absorbent rooftops, paved or covered patios,
driveways, parking lots, paved walkways, compacted soil or
rock, and streets. This category includes streets,
roads, highways, and freeways that are under the City of San
Jose’s jurisdiction and that create one acre (43,560 square
feet) or more of new impervious surface and any newly constructed
paved surface used primarily for the transportation of automobiles,
trucks, motorcycles, and other motorized vehicles. Excluded
from this category are public sidewalks, bicycle lanes, trails,
bridge accessories, guardrails, and landscape features.
Land Uses
of Concern: Uses that have the greatest potential
to contribute high levels of pollutant loading from Pollutants
of Concern, including, but not limited to: gas stations, auto
wrecking yards, loading docks, heavy automotive uses, and
various other heavy industrial and commercial uses.
Major Impervious
Surface Area: One acre
(43,560 square feet) or more of impervious surface area.
Major Project: New development projects that create one acre (43,560
square feet) or more of impervious surface area; new streets,
roads, highways and freeways built under the City’s jurisdiction
that create one acre (43,560 square feet) or more of impervious
surface area; and Significant Redevelopment Projects.
One Single-Family
Home: A project
or project expansion consisting of one single-family home
that is not part of a larger common plan of development. One
single-family home is excluded from the requirement to implement
appropriate storm water runoff treatment control measures.
An equivalent water quality benefit should be provided by
the maintenance of at least one street tree or by complying
with section 20.30.440 of the City of San Jose
Municipal Code, which provides limitations on the amount of
paved surface in front setback areas.
Pollutants
of Concern: Identified
Pollutants of Concern in the SCVURPPP Permit include certain
heavy metals (copper, nickel and mercury), excessive sediment
production from erosion due to anthropogenic activities, petroleum
hydrocarbons from sources such as used motor oil, microbial
pathogens of domestic sewage origin from illicit discharges,
the pesticides diazinon, chlordane,
dieldrin and DDT, excessive nutrient loads which may
cause or contribute to the depletion of dissolved oxygen and/or
toxic concentrations and dissolved ammonia, and other pollutants
which may cause aquatic toxicity in the receiving waters.
Post-Construction
Best Management Practice (BMP):
A method,
activity, maintenance procedure, or other management practice
designed to reduce the amount of stormwater pollutant loading
from a site. Examples of Post-Construction BMPs include proper
materials storage and housekeeping activities, public and
employee education programs, and storm inlet maintenance and
stenciling.
Post-Construction
Treatment Control Measure:
A site design
measure, landscape characteristic or permanent storm water
pollution prevention device, installed and maintained as part
of a new development or redevelopment project, that is designed
to reduce storm water pollutant loading from a site; is installed
as part of a new development or redevelopment project; and
is maintained in place after construction has been completed.
Examples of runoff treatment control measures include infiltration
devices (e.g., vegetative swales/biofilters, insert filters,
and oil/water separators) or detention/retention measures
(e.g., detention/retention ponds). Post-Construction Treatment
Control Measures are a category of BMPs.
Regional
BMP or Treatment Control Measure:
Regional
or municipal storm water detention/treatment facilities, or
land acquisition/conservation programs that protect or enhance
water quality/beneficial uses, or other specific projects/programs
(or designated functions/components of projects/programs)
that protect or enhance water quality/beneficial uses in a
manner equivalent to that which would be provided by the installation
of on-site measures, and that are specifically identified
as eligible alternative compliance options in the annual Workplan
submitted by the City pursuant to the SCVURPPP Permit.
Significant
Redevelopment Projects:
A project on a previously developed site that results
in addition and/or replacement of one acre (43,560 square
feet) or more of impervious surface. Interior remodel, routine
maintenance or repair, and exterior surface replacement or
repaving are expressly excluded from this definition. Excluded
from this category are interior remodels and routine maintenance
or repair. Excluded routine maintenance and repair includes
roof or exterior surface replacement, pavement resurfacing,
repaving and road pavement structural section rehabilitation
within the existing footprint, and any other reconstruction
work within a public street or road right-of-way where both
sides of that right-of-way are developed.
Smart Growth
Projects: A Smart Growth Project may be any one or a combination
of the following:
Transit
Oriented Project;
Project
within the Urban Core;
Project
within a redevelopment project area, adopted pursuant to the
Community Redevelopment Law, (Health & Safety Code §§ 33000
et seq.)
Low-income,
moderate-income, or senior housing project, meeting one of
the criteria of Government Code Section 65915(b)(1) or 65915(b)(2);
Brownfields
Project.
Total Project
Cost: Includes the construction (labor) and
materials cost of the physical improvements proposed; but
does not include land, transaction, financing, permitting,
demolition or off-site mitigation costs.
Transit Oriented
Project: A project
located within 2,000 feet of an existing or planned light
rail or bus station (not including simple bus stops that are
not stations), terminal, project-dedicated van or bus shuttle
service station, or major transfer point, or within 3,000
feet of an existing or planned BART, heavy rail, or intermodal
station, or a project supplying less than one-half parking
space per residential dwelling unit, or ninety percent (90%)
or less of the parking required by Tables 20-190, 20-200,
and 20-210 of Title 20 of the City of San Jose Municipal Code
where the City makes findings that a limited parking supply
is justified by existing or planned transit opportunities.
Trees Eligible
for Post-Construction Treatment Control Measure Credit: New
trees planted within 30 feet of impervious surfaces are eligible
for Post-Construction
Treatment Control Measure Credit.
100 square feet of Credit may be given for each new deciduous
tree, and 200 square feet of Credit may be given for each
new evergreen tree (see minimum sizes below). Post-Construction
Treatment Control Measure Credits
also apply to existing trees kept on a site if the trees’
canopies are within 20 feet of impervious surfaces. The Credit
is the square-footage equal to one-half of the existing tree
canopy. No
more than 25% of a site’s impervious surface can be treated
through the use of trees. Trees required by the City of San
Jose for tree removal mitigation will not count toward Post-Construction Treatment Control Measure Credit. Trees required by the
City of San Jose to fulfill the requirements of street trees
will not count toward Post-Construction
Treatment Control Measure
Credit. The trees selected shall be suitable
species for the site conditions and the design intent. Trees
should be relatively self-sustaining and long-lived.
To receive
Post-Construction
Treatment Control Measure Credit,
new deciduous trees must be at least 24-inch box in size and
at least 2 inches in diameter as measured 2 feet above finished
grade and new evergreen trees must be at least 24-inch box
in size and at least 6 feet
tall as measured from finished grade. Trees planted to meet
storm water treatment facility planting requirements will
not also receive Post-Construction
Treatment Control Measure Credit.
The Post-Construction Treatment Control
Measure Credit applies to existing trees
of 4-inch diameter or greater as measured 2 feet above finished
grade. Credit is based on one half of the square footage of
the tree canopy. Protection during construction shall be in
the form of minimizing disruption of the root system.
Urban Core: Projects that are (1) infill development
of vacant or underutilized land within areas that are already
developed with urban uses and served with urban infrastructure
(e.g., sanitary sewers, water, etc.) and are not located on
the urban fringe; or (2) any area designated on the San Jose
General Plan Land Use/Transportation Diagram for Transit Corridor
Residential (20+ DU/AC), Residential Support for the Core
(25+ DU/AC), Core Area, Neighborhood Business District, or
Transit-Oriented Development Corridor; or (3) commercial or
industrial development at a floor area ratio greater than
1; or (4) residential development at a density of not less
than eight dwelling units per acre and within one-half mile
of existing development meeting any of the three criteria
above. The Urban Core includes all “Transit Oriented Projects”
and designated Redevelopment Areas (see Health and Safety Code §§ 25000, et seq.).
This
Policy establishes that Major Projects will be required to
install Post-Construction Treatment Control Measures meeting
specified hydraulic sizing criteria, according to the following
schedule, except where impracticable:
October
15, 2003 - Major Projects requiring a permit or other direct
approval from the RWQCB, including Major Projects requiring
RWQCB certification under Section 401 of the Clean Water Act,
and Major Projects involving Land Uses of Concern;
February
15, 2005 - all other Major Projects.
This
Policy also establishes the criteria for establishing impracticability
and for evaluating Alternative Compliance Measures.
This
Policy further establishes that projects that are not subject
to Post-Construction Treatment Control Measure requirements
should include specific measures for reducing storm water
pollution to the maximum extent practicable if the project
incorporates new Major Impervious Surface Area or Major Expansion
of a use or built development. In addition, the policy establishes
general guidelines and minimum BMPs for Land Uses of Concern. Finally, it requires that
all Post-Construction Treatment Control Measures must be maintained
to operate effectively.
NUMERIC SIZING CRITERIA FOR POST-CONSTRUCTION TREATMENT CONTROL MEASURES
Except
as specified below, Major Projects shall include a Post-Construction
Treatment Measure that incorporates, at a minimum, the following
hydraulic sizing design criteria to treat storm water runoff
from the impervious surface area of the Project. Where a Significant
Redevelopment Project results in an increase, or replacement,
of more than fifty percent (50%) of the impervious surface
of a previously existing development, which was not subject
to storm water control measures, the entire impervious area
of the project site must be included in the application of
the sizing criteria. Where a Significant Redevelopment Project
results in an increase, or replacement, of not more than fifty
percent (50%) of the impervious surface of a previously existing
development, which was not subject to storm water control
measures, only the net new impervious surface area must be
included in the application of the sizing criteria.
Volume
Hydraulic Design Basis: Treatment
control measures whose primary mode of action depends on volume
capacity, such as detention/retention units or infiltration
devices (biofilters /vegetative swales, insert filters and
oil/water separators), shall be designed to treat storm water
runoff equal to:
a. the maximized storm water
quality capture volume for the area, based on historical rainfall
records, determined using the formula and volume capture coefficients
set forth in Urban Runoff Quality Management,
WEF Manual of Practice No. 23/ ASCE Manual of Practice No.
87, (1998), pages 175-178 (e.g., approximately the 85th
percentile 24-hour storm runoff event); or
the
volume of annual runoff required to achieve 80 percent or
more capture, determined in accordance with the methodology
set forth in Appendix D of the California Stormwater Best
Management Practices Handbook, (1993), using local rainfall
data.
Flow
Hydraulic Design Basis: Treatment
control measures whose primary mode of action depends on flow
capacity, such as vegetative swales, sand filters, or wetlands,
shall be sized to treat:
a. 10% of the 50-year peak
flow rate; or
b. the flow of runoff produced
by a rain event equal to at least two times the 85th percentile
hourly rainfall intensity for the applicable area, based on
historical records of hourly rainfall depths; or
c. the flow of runoff resulting
from a rain event equal to at least 0.2 inches per hour intensity.
Project
applicants will be responsible for verifying the rainfall
data used to meet the above criteria and for providing engineering
certification that the criteria have been met.
LIMITATIONS ON USE OF INFILTRATION TREATMENT MEASURES - INFILTRATION AND GROUNDWATER PROTECTION
In
order to protect groundwater from pollutants that may be present
in urban runoff, treatment control measures that function
primarily as direct infiltration devices (such as infiltration
trenches and infiltration basins) must meet, at a minimum,
the following conditions:
Pollution
prevention and source control BMPs shall be implemented at
a level appropriate to protect groundwater quality at sites
where infiltration devices are to be used;
Use
of infiltration devices shall not cause or contribute to degradation
of groundwater water quality objectives;
Infiltration
devices shall be adequately maintained to maximize pollutant
removal capabilities;
The
vertical distance from the base of any infiltration device
to the seasonal high groundwater mark shall be at least 10
feet.
Unless
storm water is first treated by a means other than infiltration,
infiltration devices shall not be recommended for areas of
industrial or light industrial activity; areas subject to
high vehicular traffic (25,000 or greater average daily traffic
on main roadway or 15,000 or more average daily traffic on
any intersecting roadway); automotive repair shops; car washes;
fleet storage areas (bus, truck, etc.); nurseries; or any
other land use or activity which may pose a high threat to
groundwater quality, as designated by the City;
Infiltration
devices shall be located a minimum of 100 feet horizontally
from any water supply wells.
ALTERNATIVES TO INSTALLATION OF POST-CONSTRUCTION TREATMENT CONTROL MEASURES
At
the City’s discretion, projects may provide an Alternative
Measure, as defined below, in lieu of demonstrating compliance
with the numeric sizing criteria, where installation of Post-Construction
Treatment Control Measures are impracticable.
i. Impracticability
- installation of a Post-Construction Treatment Control Measure
may be found impracticable if any one of the following conditions
is shown to exist:
Inadequate
space or soil conditions for an on-site treatment control
measure;
Limitations
on the ability of a treatment control measure to address pollutants
of concern;
The
site is within an area where infiltration would not be permitted
and another type of treatment is impracticable;
Projected
costs of the required measure (cost of labor and materials
for the treatment measure, plus the cost of dedicating land
to the treatment measures in lieu of otherwise allowable use)
would exceed two percent (2%) of Total Project Costs;
The
project is a Smart Growth Project, or a publicly funded or
sponsored project determined by the City to have community
or environmental benefits, including senior or child care
centers or similar projects;
Installation
of measures would result in the inability of the project sponsor
or City to comply with other regulatory requirements at the
federal, state and local levels (for example, seismic building
code requirements); or
Maintenance,
inspection and/or monitoring measures would impose an undue
burden on the project sponsor or City.
ii. Alternative Measures - Major
Projects which are not required to install Post-Construction
Treatment Control Measures on-site must provide equivalent
protection or enhancement of water quality/beneficial uses
through one of the following Alternative Measures:
Regional Solution. Participation
in a Regional Project or Program that has capacity/credit
to address storm water impacts equivalent to the impacts produced
by the subject Major Project. Where feasible, the Regional
Project must discharge to/address the receiving waters affected
by the subject Major Project.
Water Quality Benefit Project.
In its discretion, the City may find that all Smart
Growth Projects provide equivalent water quality benefit.
For other projects, Alternative Measures may be found by the
City to exist where the project sponsor documents that the
development of the site itself, the nature of the site design,
its location in the watershed and/or the proposed change in
use protects/enhances water quality/beneficial uses such that
post-project water quality/beneficial uses conditions are
likely to equal or exceed pre-project conditions.
Equivalent Project - The project provides treatment for a pollutant loading
or volume of storm water runoff that is equivalent to the
treatment that would be provided by the otherwise required
Post-Construction Control Treatment Measure. Equivalent projects
may include off-site treatment, stream restoration or other
activities that limit or mitigate impacts from excessive erosion
or sedimentation.
All
new multi-family residential and non-residential projects
including new Major Impervious Surface Areas
or projects proposing Major Expansion should include Post-Construction
Treatment Control Measures to the maximum extent practicable.
For all projects with suitable landscape areas, vegetative
swales or other biofilters are recommended because they are
relatively economical and require limited maintenance. If
these measures are not feasible or adequate to treat the volume
or flow of runoff required for Major Projects, other post-construction
BMPs/treatment control measures should be incorporated.
Gas Stations
or Equipment Fueling Facilities:
All new fueling
stations or expansion
of such uses should include the following BMPs. 1) Install
and maintain a treatment control measure. 2) Pave the fueling
area floors with an impermeable surface (i.e., portland cement
concrete or equivalent smooth impervious surface). 3) Cover
the fueling areas with a canopy or cover that extends a minimum
of ten feet in each direction from each pump. Alternatively,
cover the fueling areas with a canopy or cover that has minimum
dimensions equal to or greater than the area within the grade
break or fuel dispensing area. (The fuel dispensing area is
defined as the area extending a minimum of 6.5 feet from the
corner of each fuel dispenser or the length at which the hose
and nozzle assembly may be operated plus a minimum of one
foot, whichever is greater. In no case should the canopy or
cover drain onto the fueling area.) 4) Grade the fuel area
to prevent water draining toward the fueling area. 5) Grade
the fuel area with the minimum slope necessary to prevent
ponding. 6) Separate the fueling area from the rest of the
site by a grade break that prevents run-on of storm water
to the maximum extent practicable. 7) Dry sweep the fueling
area routinely. 8) Stencil all on-site storm drains in conformance
with the City’s requirements. 9) Prepare a spill cleanup plan
in conformance with the City of San Jose Fire Code.
Auto Wrecking
Yards: All new auto wrecking yards or major
expansion of such uses should include the following: 1) install
and maintain a treatment control measure; 2) pave all outside
vehicle storage areas; 3) cover fluids drainage areas; 4)
pave fluids drainage areas with impermeable materials; 5)
construct a berm around fluids drainage areas and grade the
site to prevent water draining toward this working area; 6)
remove and store batteries in conformance with the City Fire
Code; and 7) prepare and execute the spill prevention plan
in conformance with the City Fire Code.
Loading Docks: All new loading docks or major expansion
of such uses should include the following: 1) pave the loading
dock floor with an impermeable surface; 2) cover the loading
dock; 3) grade the site to minimize run-on to and runoff from
the loading area; 4) position roof downspouts to direct storm
water away from the loading area; 5) drain water from the
loading dock areas to the sanitary sewer, or divert and collect
the water for ultimate discharge to the sanitary sewer; 6)
equip loading dock areas draining directly to the sanitary
sewer with a spill control valve or equivalent device that
is kept closed during periods of operation; 7) install door
skirts between the trailers and the building to prevent exposure
of loading activities to rain.
Other Unenumerated
Uses of Concern: Other Land
Uses Of Concern not enumerated in this
policy generating equivalent amounts of heavy pollutants may
need to include specific BMPs to treat storm water pollutants.
Those BMPs would be determined in conjunction with the development
permit for the project.
All
Post-Construction Treatment Control Measures included in new
projects must be installed, operated, and maintained by qualified
personnel. On-site inlets must be stenciled in conformance
with City requirements; and cleaned out at least once per
year, prior to the wet season.
The
property owner/site manager must keep a maintenance and inspection
schedule and record to ensure that the treatment control measures
continue to operate effectively. Copies of this schedule and
record must be provided to the City upon request, and must
be made available for inspection at the site at all times.
Trees approved for Post-Construction
Control Measure Credit shall be maintained and protected on
the site after construction and for the life of the development
(until any approved redevelopment occurs in the future). During
the life of the development, trees approved for Post-Construction
Treatment Control Measure Credit
shall not be removed without approval from the City. Trees
that are removed or die shall be replaced within six (6) months
with species approved by the City of San Jose.