The ordinance codified in this chapter shall be known as the
"Post-Construction Best Management Practices (BMP) Design Standards
of the City of Lemon Grove."
(Ord. 435 § 1, 2015)
A.
The
municipal stormwater National Pollutant Discharge Elimination System
(NPDES) permit (Order No. R9-2013-0001, NPDES No. CAS0109266, as may
be amended, hereinafter referred to as "municipal permit") issued
to San Diego County, San Diego County Regional Airport Authority,
the Port of San Diego, and eighteen cities by the San Diego Regional
Water Quality Control Board (Regional Board) on May 8, 2013, requires
the development and implementation of a program addressing urban runoff
pollution issues in development planning for public and private projects.
B.
The requirement to implement a program for development planning is based on federal and state statutes including: Section 402 (p) of the Clean Water Act, Section 6217 of the Coastal Zone Act Reauthorization Amendments of 1990 ("CZARA"), and the California Water Code. The Clean Water Act amendments of 1987 established a framework for regulating urban runoff discharges from municipal, industrial, and construction activities under the NPDES program. The municipal permit requires the adoption of a local BMP Design Manual that incorporates the minimum low impact development (LID) and BMP requirements developed in the Countywide Model BMP Design Manual. The BMP Design Manual shall be approved by resolution of the city council that will establish implementing regulations to this chapter and Chapter 8.48 (Stormwater Management and Discharge Control).
(Ord. 435 § 1, 2015)
The requirements of this chapter were developed to address post-construction
urban runoff pollution from new development and redevelopment applications.
The goal of this chapter is to establish requirements to ensure to
the maximum extent practicable (MEP) that development does not increase
pollutant loads from a project site or result in increased erosion
in channels or streams downstream of the development.
(Ord. 435 § 1, 2015)
The requirements set forth in this chapter shall apply to the development plan approval process for discretionary development applications, and prior to issuing development permits for ministerial projects. All "development projects" must include control measures to reduce the discharge of stormwater pollutants to the MEP (Sections 8.52.100 through 8.52.130). Development projects are construction, rehabilitation, redevelopment, or reconstruction activities that have the potential to contact stormwater and contribute an anthropogenic source of pollutants or reduce the natural absorption and infiltration abilities of the land. Each development project is classified as either a "standard development project" or a "priority development project." This chapter includes regulations that apply to all development projects as well as a separate suite of regulations that apply only to priority development projects. Projects that meet any of the criteria in Section 8.52.060 are not considered development projects and are not subject to the requirements of this chapter.
The following types of development projects are considered priority
development projects:
A.
New
development projects that create ten thousand square feet or more
of impervious surfaces (collectively over the entire project site).
This includes commercial, industrial, residential, mixed-use, and
public development projects on public or private land.
B.
Redevelopment
projects that create and/or replace five thousand square feet or more
of impervious surface (collectively over the entire project site on
an existing site of ten thousand square feet or more of impervious
surfaces). This includes commercial, industrial, residential, mixed-use,
and public development projects on public or private land.
C.
New
and redevelopment projects that create and/or replace five thousand
square feet or more of impervious surface (collectively over the entire
project site), and support one or more of the following uses:
1.
Restaurants.
This category is defined as a facility that sells prepared foods and
drinks for consumption, including stationary lunch counters and refreshment
stands selling prepared foods and drinks for immediate consumption
(SIC code 5812).
2.
Hillside
Development Projects. This category includes development on any natural
slope that is twenty-five percent or greater.
3.
Parking
Lots. This category is defined as a land area or facility for the
temporary parking or storage of motor vehicles used personally, for
business, or for commerce.
4.
Streets,
Roads, Highways, Freeways, and Driveways. This category is defined
as any paved impervious surface used for the transportation of automobiles,
trucks, motorcycles, and other vehicles.
D.
New
or redevelopment projects that create and/or replace two thousand
five hundred square feet or more of impervious surface (collectively
over the entire project site), and discharging directly to an environmentally
sensitive area (ESA). "Discharging directly to" includes flow that
is conveyed overland a distance of two hundred feet or less from the
project to the ESA, or conveyed in a pipe or open channel any distance
as an isolated flow from the project to the ESA (i.e., not commingled
with flows from adjacent lands).
E.
New
development projects, or redevelopment projects that create and/or
replace five thousand square feet or more of impervious surface, that
support one or more of the following uses:
1.
Automotive
Repair Shops. This category is defined as a facility that is categorized
in any one of the following Standard Industrial Classification (SIC)
codes: 5013, 5014, 5541, 7532-7534, or 7536-7539.
F.
New
or redevelopment projects that result in the disturbance of one or
more acres of land and are expected to generate pollutants post-construction.
(Ord. 435 § 1, 2015)
The provisions of Chapter 8.48 (Stormwater Management and Discharge Control), including the definitions and enforcement provisions, shall be applicable to this chapter as though fully set forth herein.
(Ord. 435 § 1, 2015)
The following activities are not considered "development projects,"
and the requirements of this chapter do not apply to them:
A.
Replacement
of impervious surfaces that are part of a routine maintenance activity,
such as:
1.
Replacing
roof material on an existing building;
2.
Rebuilding
a structure to original design after damage from earthquake, fire
or similar disasters;
3.
Restoring
pavement or other surface materials affected by trenches from utility
work;
4.
Resurfacing
existing roads and parking lots, including slurry, overlay, and restriping;
5.
Routine
replacement of damaged pavement, including full depth replacement,
if the sole purpose is to repair the damage;
6.
Constructing
new sidewalk, pedestrian ramps or bike lanes on existing roads (within
existing street right-of-way);
7.
Restoring
a historic building to its original historic design.
B.
Repair
or improvements to an existing building or structure that do not alter
the size:
1.
Plumbing,
electrical and HVAC work;
2.
Interior
alterations including major interior remodels and tenant build-out
within an existing commercial building;
3.
Exterior
alterations that do not change the general dimensions and structural
framing of the building (does not include building additions or projects
where the existing building is demolished).
(Ord. 435 § 1, 2015)
Interpretation of this chapter shall assure consistency with
the purpose and intent of this chapter and shall implement the requirements
of the MS4 permit. This chapter is not intended to interfere with,
abrogate or annul any other chapter, rule or regulation, statute,
or other provision of law. The requirements of this chapter should
be considered minimum requirements, and where any provision of this
chapter imposes restrictions different from those imposed by any other
chapter, rule or regulation, or other provision of law, whichever
provisions are more restrictive or impose higher protective standards
for human health or the environment shall take precedence.
(Ord. 435 § 1, 2015)
The requirements of this chapter shall be incorporated into the project design and shown on the plans prior to approval of discretionary permits. For projects requiring only ministerial permits, the requirements of this chapter shall be incorporated into the project design and shown on the plans prior to the issuance of any ministerial permits. City departments carrying out public projects that are not required to obtain permits shall be responsible for ensuring the requirements of this chapter are incorporated into the project design and shown on the plans prior to bidding for construction contracts, or equivalent. For public projects, the requirements of this chapter must be incorporated into the project design and shown on the plans before allowing the project to commence. In addition, all projects, both public and private, shall submit a post-construction BMP plan documenting how the project design complies with the requirements of this chapter before permits are issued for private projects and before public projects are allowed to commence. The city of Lemon Grove BMP Design Manual, which shall be adopted by resolution of the city council as an implementing regulation of this chapter and Chapter 8.48, shall be available on the city's website.
(Ord. 435 § 1, 2015)
All development projects shall implement source control and site design BMPs. Furthermore, priority development projects shall implement structural pollutant control BMPs. The final determination of the applicability and feasibility of all BMPs in this chapter shall be made by the development services director. The stormwater BMPs shall adhere to the requirements of this chapter, and shall be correctly designed so as to remove pollutants to the MEP. Priority projects must also be designed so that runoff rates and durations are controlled to maintain or reduce downstream erosion conditions and protect stream habitat. Design criteria and procedures for hydromodification management are identified in Section 8.52.130 and shall be further set forth in the city of Lemon Grove BMP Design Manual, which shall be adopted by resolution of the city council as an implementing regulation of this chapter and Chapter 8.48.
(Ord. 435 § 1, 2015)
All development projects must meet the following requirements:
A.
On-site
BMPs shall be located so as to remove pollutants from runoff prior
to its discharge to any receiving waters, and as close to the source
as possible.
B.
Structural
BMPs shall not be constructed within the waters of the U.S.
C.
On-site
BMPs shall be designed and implemented with measures to avoid the
creation of nuisances or pollutions associated with vectors (e.g.,
mosquitoes, rodents, or flies).
(Ord. 435 § 1, 2015)
All development projects must implement LID site design BMPs
and source control BMPs as described below.
A.
Site
design performance standards define minimum requirements for how a
site must incorporate LID site design BMPs, including the location
of BMPs and the use of integrated site design practices. The following
site design practices must be implemented at all development projects,
where applicable and feasible:
1.
Maintenance
or restoration of natural storage reservoirs and drainage corridors
(including topographic depressions, areas of permeable soils, natural
swales, and ephemeral and intermittent streams).
a.
Development projects that propose to disturb water bodies shall also
comply with all applicable requirements of other agencies, including,
but not limited to, the US Army Corps of Engineers, the California
Department of Fish and Wildlife, and the San Diego Regional Water
Quality Control Board;
2.
Buffer
zones for natural water bodies (where buffer zones are technically
infeasible, the project applicant shall include other buffers such
as trees, access restrictions, or similar measures);
3.
Conservation
of natural areas within the project footprint including existing trees,
other vegetation, and soils;
4.
Construction
of streets, sidewalks, or parking lot aisles to the minimum widths
necessary, provided public safety is not compromised;
5.
Minimization
of the impervious footprint of the project;
6.
Minimization
of soil compaction to landscaped areas;
7.
Disconnection
of impervious surfaces through distributed pervious areas;
8.
Landscaped
or other pervious areas designed and constructed to effectively receive
and infiltrate, retain and/or treat runoff from impervious areas,
prior to discharging to the MS4;
9.
Small
collection strategies located at, or as close as possible to, the
source (i.e., the point where stormwater initially meets the ground)
to minimize the transport of runoff and pollutants to the MS4 and
receiving waters;
10.
Use of permeable materials for projects with low traffic areas and
appropriate soil conditions;
11.
Landscaping with native or drought tolerant species; and
12.
Harvesting and using precipitation.
B.
The
following source control BMPs must be implemented at all development
projects where applicable and feasible:
1.
Prevention
of illicit discharges into the MS4;
2.
Storm
drain system stenciling or signage;
3.
Protection
of outdoor material storage areas from rainfall, run-on, runoff, and
wind dispersal;
4.
Protection
of materials stored in outdoor work areas from rainfall, run-on, runoff,
and wind dispersal;
5.
Protection
of trash storage areas from rainfall, run-on, runoff, and wind dispersal;
and
6.
Additional
BMPs to control discharges of pollutants from the following sources,
as applicable:
a.
On-site storm drain inlets,
b.
Interior floor drains and elevator shaft sump pumps,
c.
Interior parking garages,
d.
Need for future indoor and structural pest control,
e.
Landscape/outdoor pesticide use,
f.
Pools, spas, ponds, decorative fountains, and other water features,
g.
Food service,
h.
Refuse areas,
i.
Industrial processes,
j.
Outdoor storage of equipment or materials,
k.
Vehicle and equipment cleaning,
l.
Vehicle and equipment repair and maintenance,
m.
Fuel dispensing areas,
n.
Loading docks,
o.
Fire sprinkler test water,
p.
Miscellaneous drain or wash water,
q.
Plazas, sidewalks, and parking lots.
|
Detailed requirements for selection of appropriate site design and source control BMPs shall be further set forth in the city of Lemon Grove BMP Design Manual, which shall be adopted by resolution of the city council as an implementing regulation of this chapter and Chapter 8.48.
|
(Ord. 435 § 1, 2015)
All priority development projects must implement on-site structural
BMPs to control pollutants in stormwater that may be discharged from
a project as follows:
A.
Each
priority development project must implement LID BMPs that are designed
to retain (i.e., intercept, store, infiltrate, evaporate, and evapotranspire)
on-site the pollutants contained in the volume of stormwater runoff
produced from a twenty-four-hour 85th percentile storm event (design
capture volume).
1.
If
implementing BMPs to retain the full design capture volume on-site
for a priority development project is not technically feasible, then
the priority development project may utilize biofiltration BMPs. Biofiltration
BMPs must be designed to have an appropriate hydraulic loading rate
to maximize stormwater retention and pollutant removal, as well as
to prevent erosion, scour, and channeling within the BMP, and must
be sized to:
a.
Treat one and one-half times the design capture volume not reliably
retained on-site; or
b.
Treat the design capture volume not reliably retained on-site with
a flow-thru design that has a total volume, including pore spaces
and pre-filter detention volume, sized to hold at least three-fourths
times the portion of the design capture volume not reliably retained
on-site.
Detailed requirements for proper selection and sizing of structural BMPs shall be further set forth in the Lemon Grove BMP Design Manual, which shall be adopted by resolution of the city council as an implementing regulation of this chapter and Chapter 8.48.
(Ord. 435 § 1, 2015)
Priority development projects must implement on-site BMPs to
manage hydromodification that may be caused by stormwater runoff discharged
from a project as follows:
A.
Post-project
flow rates and durations must meet the following criteria:
1.
For
flow rates ranging from ten percent, thirty percent or fifty percent
of the pre-development two-year runoff event (0.1Q2, 0.3Q2, or 0.5Q2)
to the pre-development ten-year runoff event (Q10), the post-project discharge rates and durations shall not deviate
above the pre-development rates and durations by more than ten percent
over and more than ten percent of the length of the flow duration
curve. The specific lower flow threshold will depend on the erosion
susceptibility of the receiving stream for the project site. Guidelines
for selection of the appropriate lower flow threshold are provided
in the San Diego Hydromodification Management Plan.
2.
For
flow rates ranging from the lower flow threshold to Q5, the post-project peak flows shall not exceed pre-development peak
flows. For flow rates from Q5 to Q10, post-project peak flows may exceed pre-development
flows by up to ten percent for a one-year frequency interval. For
example, post-project flows could exceed pre-development flows by
up to ten percent for the interval from Q9 to
Q10 or from Q5.5 to
Q6.5, but not from Q8 to Q10.
B.
Each
priority development project must avoid critical coarse sediment yield
areas identified in the Watershed Management Area Analysis or implement
measures that allow critical coarse sediment to be discharged to receiving
waters, such that there is no net impact to the receiving water.
C.
At the
development services director's discretion, the city may exempt a
priority development project from the hydromodification management
BMP performance requirements described in this section where the project
discharges stormwater runoff to:
1.
Existing
underground storm drains discharging directly to water storage reservoirs,
lakes, enclosed embayments, or the Pacific Ocean;
2.
Conveyance
channels whose bed and bank are concrete lined all the way from the
point of discharge to water storage reservoirs, lakes, enclosed embayments,
or the Pacific Ocean; or
3.
An
area identified by the copermittees as appropriate for an exemption
by the optional Watershed Management Area Analysis.
(Ord. 435 § 1, 2015)
If the priority development project is a redevelopment project,
the structural BMP performance requirements and hydromodification
management requirements apply to redevelopment priority development
projects as follows:
A.
Where
redevelopment results in the creation or replacement of impervious
surface in an amount of less than fifty percent of the surface area
of the previously existing development, then the structural BMP performance
requirements for priority development projects apply only to the creation
or replacement of impervious surface, and not the entire development;
or
B.
Where
redevelopment results in the creation or replacement of impervious
surface in an amount of more than fifty percent of the surface area
of the previously existing development, then the structural BMP performance
requirements for priority development projects apply to the entire
development.
(Ord. 435 § 1, 2015)
Development projects shall design the timing and application
methods of irrigation water to prevent the runoff of excess irrigation
water into the stormwater conveyance system. The following methods
to reduce excessive irrigation runoff shall be considered, and incorporated
and implemented where determined applicable and feasible by the development
services director. (Detached residential homes may be exempted from
these measures by the community development director as long as the
project design includes methods to minimize runoff):
A.
Employing
rain shutoff devices to prevent irrigation after precipitation.
B.
Designing
irrigation systems to each landscape area's specific water requirements.
C.
Using
flow reducers or shutoff valves triggered by a pressure drop to control
water loss in the event of broken sprinkler heads or lines.
(Ord. 435 § 1, 2015)
The following requirements apply to shared and interim stormwater
BMPs:
A.
Shared
stormwater BMPs shall be operational prior to the use of any dependent
development or phase of development. The shared BMPs shall only be
required to treat the dependent developments or phases of development
that are in use;
B.
Interim
stormwater BMPs that provide equivalent or greater treatment than
is required for the permanent structural BMPs may be implemented by
a dependent development until each shared BMP is operational. If interim
BMPs are selected, the BMPs shall remain in use until permanent BMPs
are operational.
(Ord. 435 § 1, 2015)
Infiltration devices shall comply with the criteria established in the Lemon Grove BMP Design Manual, which shall be adopted by resolution of the city council as an implementing regulation of this chapter and Chapter 8.48. These conditions do not apply to structural treatment BMPs which allow incidental infiltration and are not designed to primarily function as infiltration devices (such as grassy swales, detention basins, vegetated buffer strips, constructed wetlands, etc.). At a minimum, such infiltration BMPs must be in conformance with the design criteria listed below, unless the development project applicant demonstrates that one or more of the specific design criteria listed below are not necessary to protect groundwater quality. The design criteria listed below do not apply to small infiltration systems dispersed throughout a development project.
A.
Runoff
shall undergo pretreatment to remove both physical and chemical contaminants,
such as sedimentation or filtration, prior to infiltration.
B.
Pollution
prevention and source control BMPs shall be implemented at a level
appropriate to protect groundwater quality at sites where infiltration
structural treatment BMPs are to be used.
C.
Infiltration
BMPs must be adequately maintained to remove pollutants in stormwater
to the maximum extent practicable.
D.
The
vertical distance from the base of any infiltration structural treatment
BMP to the seasonal high groundwater mark shall be at least ten feet
or as determined on an individual, site-specific basis by the development
services director. Where groundwater does not support beneficial uses,
this vertical distance criterion may be reduced, provided groundwater
quality is maintained.
E.
The
soil through which infiltration is to occur shall have physical and
chemical characteristics (such as appropriate cation exchange capacity,
organic content, clay content, and infiltration rate) which are adequate
for proper infiltration durations and treatment of urban runoff for
the protection of groundwater beneficial uses.
F.
Infiltration
structural treatment BMPs shall not be used for areas of industrial
or light industrial activity and other high threat to water quality
land uses and activities as designated by the development services
director, unless source control BMPs to prevent exposure of high threat
activities are implemented, or runoff from such activities is first
treated or filtered to remove pollutants prior to infiltration.
G.
The
horizontal distance between the base of any infiltration structural
BMP and any water supply wells shall be one hundred feet or as determined
on an individual, site-specific basis by the development services
director.
(Ord. 435 § 1, 2015)
Structural BMPs shall not be considered "effective," and shall
not be accepted as meeting the MEP standard, unless a mechanism is
in place that will ensure ongoing long-term maintenance of all structural
BMPs. As part of project review, if a project proponent is required
to include interim or permanent structural BMPs in project plans,
and if the development services director does not provide a mechanism
for BMP maintenance, the project proponent shall provide verification
of maintenance requirements through such means as may be appropriate,
at the discretion of the development services director, including,
but not limited to, covenants, legal agreements, maintenance agreements,
and/or conditional use permits.
(Ord. 435 § 1, 2015)
A.
Public
Equity Maintenance. The city council may approve a public or acceptable
quasi-public entity (e.g., the County Flood Control District, or annex
to an existing assessment district, an existing utility district,
a state or federal resource agency, or a conservation conservancy)
to assume responsibility for maintenance, repair and replacement of
the BMP. Unless acceptable to the city council, public entity maintenance
agreements shall ensure estimated costs are front-funded or reliably
guaranteed, (e.g., through a trust fund, assessment district fees,
bond, letter of credit or similar means). In addition, the city council
may seek protection from liability by appropriate releases and indemnities.
The city council shall have the authority to approve stormwater BMPs
proposed for transfer to any other public entity within its jurisdiction
before installation. The city council shall be involved in the negotiation
of maintenance requirements with any other public entities accepting
maintenance responsibilities within their respective jurisdictions;
and in negotiations with the resource agencies responsible for issuing
permits for the construction and/or maintenance of the facilities.
The city council must be identified as a third party beneficiary empowered
to enforce any such maintenance agreement within their respective
jurisdictions.
B.
Project
Proponent Agreement to Maintain Stormwater BMPs. The city council
may enter into a contract with the project proponent obliging the
project proponent to maintain, repair and replace the stormwater BMP
as necessary into perpetuity. Security may be required.
C.
Assessment
Districts. The city council may approve an assessment district or
other funding mechanism created by the project proponent to provide
funds for stormwater BMP maintenance, repair and replacement on an
ongoing basis. Any agreement with such a district shall be subject
to the public entity maintenance provisions above.
D.
Lease
Provisions. In those cases where the city holds title to the land
in question, and the land is being leased to another party for private
or public use, the city may assure stormwater BMP maintenance, repair
and replacement through conditions in the lease.
E.
Conditional
Use Permits. For discretionary projects only, the city council may
assure maintenance of stormwater BMPs through the inclusion of maintenance
conditions in the conditional use permit. Security may be required.
F.
Alternative
Mechanisms. The city council may accept alternative maintenance mechanisms
if such mechanisms are as protective as those listed above.
(Ord. 435 § 1, 2015)
For discretionary projects, the city-approved method of stormwater
BMP maintenance shall be incorporated into the project's permit, and
shall be consistent with permits issued by resource agencies, before
city approval of discretionary permits. For projects requiring only
ministerial permits, the approved method of stormwater BMP maintenance
shall be incorporated into the permit conditions before the issuance
of any ministerial permits. In all instances, the project proponent
shall provide proof of execution of an approved method of maintenance
repair and replacement before the issuance of construction approvals.
Public projects that are not required to obtain permits shall be responsible
for ensuring that an approved method of stormwater BMP maintenance
repair and replacement is executed prior to the commencement of construction.
For all properties, the verification mechanism will include the project
proponent's signed statement, as part of the project application,
accepting responsibility for all structural BMP maintenance, repair
and replacement, until a city approved entity agrees to assume responsibility
for structural BMP maintenance, repair and replacement.
(Ord. 435 § 1, 2015)
A.
Operation
and Maintenance (O&M) Plan. An O&M plan, prepared by the project
proponent shall be included in the post-construction BMP plan for
all priority development projects. The O&M plan identifies the
designated party responsible for maintaining stormwater post-construction
BMP(s) and describes typical maintenance activities and frequencies.
Project proponents for all priority development projects shall also
submit a completed storm water facilities maintenance agreement to
assure ongoing long-term maintenance of all structural BMPs. The storm
water facilities maintenance agreement runs with the land. Parties
responsible for the O&M plan shall retain maintenance records
for at least five years. These documents shall be made available to
the city for inspection upon request at any time.
B.
Access
Easement/Agreement. The development services director may require
the project proponent to submit a copy of an executed access easement
that shall be binding on the land throughout the life of the project,
until such time that the stormwater BMP requiring access is replaced.
(Ord. 435 § 1, 2015)
