A. Objective: The provisions of this section establish requirements for construction activities and facility operations of development and redevelopment projects to comply with the current municipal NPDES permit (order no. R4-2012-0175), to lessen the water quality impacts of development by using smart growth practices, and integrate LID practices and standards for stormwater pollution mitigation through means of infiltration, evapotranspiration, biofiltration, and rainfall harvest and use.
B. Scope: This section contains requirements for stormwater pollution control measures in development and redevelopment projects and authorizes the city to further define and adopt stormwater pollution control measures, and to develop LID principles and requirements, including, but not limited to, the objectives and specifications for integration of LID strategies, alternative compliance measures from the LID requirements for projects that demonstrate technical infeasibility to retain the stormwater quality design volume (SWQDv) on site or where an opportunity exists for regional groundwater replenishment as defined in the municipal NPDES permit, and collect funds for projects that are granted alternative compliance measures. Except as otherwise provided herein, the city shall administer, implement and enforce the provisions of this section.
C. Applicability: This section applies to the following new development and redevelopment projects which are subject to city conditioning and approval:
1. New Development Projects:
a. All development projects equal to one acre or greater of disturbed area and adding more than ten thousand (10,000) square feet of impervious area;
b. Industrial parks with ten thousand (10,000) square feet or more of surface area;
c. Commercial malls with ten thousand (10,000) square feet or more of surface area;
d. Retail gasoline outlets with five thousand (5,000) square feet or more of surface area;
e. Restaurants (SIC 5812) with five thousand (5,000) square feet or more of surface area;
f. Parking lots with five thousand (5,000) square feet or more of impervious area or with twenty five (25) or more parking spaces;
g. Single-family hillside residential developments or redevelopments;
h. Street and road construction of ten thousand (10,000) square feet or more of impervious surface area shall follow USEPA guidance regarding managing wet weather with green infrastructure: green streets (December 2008 EPA-833-F-08-009) to the maximum extent practicable. Street and road construction applies to stand alone streets, roads, highways, and freeway projects, and also applies to streets within larger projects;
i. Automotive service facilities (SIC 5013, 5014, 5511, 5541, 7532-7534 and 7536-7539) with five thousand (5,000) square feet or more of surface area;
j. Projects located in or directly adjacent to, or discharging directly to a significant ecological area (SEA), where the development will:
(1) Discharge stormwater runoff that is likely to impact a sensitive biological species or habitat; and
(2) Create two thousand five hundred (2,500) square feet or more of impervious surface area.
2. Redevelopment Projects: Redevelopment projects in the foregoing subject categories that meet redevelopment thresholds (pursuant to the municipal NPDES permit), which include:
a. Land disturbing activities which create, add, or replace five thousand (5,000) square feet or more of impervious surface area on an already developed site excluding single-family dwellings and accessory structures.
b. Land disturbing activities which create, add, or replace ten thousand (10,000) square feet or more of impervious surface area on existing single-family dwellings and accessory structures.
c. Where redevelopment results in an alteration to more than fifty percent (50%) of the impervious surface of a previously existing development, and the existing development was not subject to postdevelopment stormwater quality control requirements, the entire project must be mitigated.
d. Where redevelopment results in an alteration to less than fifty percent (50%) of the impervious surface of a previously existing development, and the existing development was not subject to postdevelopment stormwater quality control requirements, only the alteration must be mitigated, and not the entire development.
e. Existing single-family dwelling and accessory structures are exempt from the redevelopment requirements unless such projects create, add, or replace ten thousand (10,000) square feet of impervious surface.
D. LID Standards Manual: The director shall prepare, maintain, and update, as deemed necessary and appropriate, a manual ("LID Standards Manual"), which shall include urban and stormwater runoff quantity and quality control development principles and technologies for achieving compliance with the provisions of this section. The "LID Standards Manual" shall also include technical feasibility and implementation parameters, as well as other rules, requirements, and procedures as the director deems necessary, for implementing the provisions of this chapter.
E. Specific Requirements:
1. New Single-Family Hillside Homes: To the extent that the city may lawfully impose conditions, mitigation measures, or other requirements on the development or construction of a single- family home in a Hillside Area, a single-family Hillside home development or redevelopment project shall implement mitigation measures to:
a. Conserve natural areas;
b. Protect slopes and channels;
c. Provide storm drain system stenciling and signage;
d. Divert roof runoff to vegetated areas before discharge unless the diversion would result in slope instability; and
e. Direct surface flow to vegetated areas before discharge unless the diversion would result in slope instability.
2. New Development And Redevelopment Projects: New development and redevelopment projects are required to control pollutants and runoff volume from the project site by minimizing the impervious surface area and controlling runoff through infiltration, bioretention, and/or rainfall harvest and use in that preferred order, in accordance with the standards set forth in the municipal NPDES permit and the "LID Standards Manual". High removal efficiency BMPs shall comply with the standards and requirements of the "LID Standards Manual".
3. Project Plans: An applicant for a new development or a redevelopment project identified in this article shall incorporate into the applicant's project plans a stormwater mitigation plan which includes those BMPs necessary to control stormwater pollution from the completed project. Structural or treatment control BMPs (including, as applicable, postconstruction treatment control BMPs) set forth in project plans shall meet the design standards set forth in the municipal NPDES permit and the "LID Standards Manual".
4. New Development/Redevelopment Project Performance Criteria:
a. All new development and redevelopment projects, unless otherwise exempted herein or in the municipal NPDES permit, shall comply with part VI.D.7.c of the municipal NPDES permit.
b. Postconstruction BMPs to mitigate stormwater pollution are required for all new development and redevelopment projects identified in this article unless alternative measures are allowed as provided in part VI.D.7.c of the municipal NPDES permit.
c. BMPs must be implemented to retain on site the stormwater quality design volume (SWQDv), defined as runoff from either: 1) the 0.75 inch, 24-hour rain event; or 2) the 85th percentile, 24-hour event, as determined from the Los Angeles County 85th percentile precipitation isohyetal map, whichever is greater.
d. BMPs shall meet the design specifications and on site retention potential outlined in the part VI.D.7.c of the municipal NPDES permit and the "LID Standards Manual".
e. Single-family Hillside home development projects are exempt from the new development/redevelopment project performance criteria of part VI.D.7.c of the municipal NPDES permit unless they create, add, or replace ten thousand (10,000) square feet or more of impervious surface area.
f. Street and road construction projects of ten thousand (10,000) square feet or more of impervious surface area are exempt from the new development/redevelopment project performance criteria of part VI.D.7.c of the municipal NPDES permit but shall adhere to the city's green streets policy.
g. Projects unable to retain one hundred percent (100%) of the SWQDv on site due to technical infeasibility as defined in the municipal NPDES permit must implement alternative compliance measures in accordance with part VI.D.7.c of the municipal NPDES permit. When, as determined by the city, one hundred percent (100%) on site retention of the SWQDv is technically infeasible, partially or fully. The infeasibility shall be demonstrated in the submitted stormwater mitigation plan. The technical infeasibility may result from conditions that may include, but are not limited to:
(1) The infiltration rate of saturated in-situ soils is less than 0.3 inches per hour and it is not technically feasible to amend the in-situ soils to attain an infiltration rate necessary to achieve reliable performance of infiltration or bioretention BMPs in retaining SWQDv on site;
(2) Locations where seasonal high groundwater is within five (5) to ten feet (10') of surface grade;
(3) Locations within one hundred feet (100') of a groundwater well used for drinking water;
(4) Locations with potential geotechnical hazards;
(5) Smart growth and infill or redevelopment locations where the density and/or nature of the project would create significant difficulty for compliance with the on site volume retention requirement.
h. If partial or complete retention is technically infeasible, the project site may biofiltrate 1.5 times the portion of the remaining SWQDv that is not reliably retained on site, biofiltration BMPs must adhere to the design specifications provided in the municipal NPDES permit of part VI.D.7.c.
i. Additional alternative compliance options such as off site infiltration may be available to the project site. The project site should contact the city to determine eligibility.
j. The remaining SWQDv that cannot be retained or biofiltered on site must be treated on site to reduce pollutant loading. BMPs must be selected and designed to meet pollutant specific benchmarks as required per the municipal NPDES permit. Flow through BMPs may be used to treat the remaining SWQDv and must be sized based on a rainfall intensity of:
(1) 0.2 inch per hour, or
(2) The 1-year, 1-hour rainfall intensity as determined from the most recent Los Angeles County isohyetal map, whichever is greater.
F. Issuance Of Discretionary Permits: No discretionary permit may be issued for any new development or redevelopment project identified in this section until the authorized enforcement officer confirms the project plans comply with the applicable requirements of this section.
G. Issuance Of Certificates Of Occupancy: As a condition for issuing a certificate of occupancy for new development or redevelopment projects identified in this article, the authorized enforcement officer shall require property owners or their representative(s) to build all the stormwater pollution control BMPs and structural or treatment control BMPs that are shown on the approved project plans and consistent with the stormwater mitigation plan and to submit a signed certification statement stating that the site and all structural or treatment control BMPs will be maintained in compliance with the municipal NPDES permit, the stormwater mitigation plan, and other applicable regulatory requirements.
H. Information Provided By Owners: With the exception of simple LID BMPs (as defined in this article) implemented on single- family residences, consistent with part VI.D.7.d(iii) of the municipal NPDES permit, project owners shall provide an operation and maintenance plan, monitoring plan where required, and verification of ongoing maintenance provisions for LID practices and treatment control BMPs including, but not limited to: final map conditions, legal agreements, covenants, conditions or restrictions, CEQA mitigation requirements, conditional use permits, and/or other legally binding maintenance agreements. These maintenance records must be kept on site for treatment BMPs implemented on single-family residences.
I. Transfer Of Properties Subject To Requirement For Maintenance Of Structural And Treatment Control BMPs:
1. The transfer or lease of a property subject to a requirement for maintenance of structural and treatment control BMPs shall include conditions requiring the transferee and its successors and assigns to either: a) assume responsibility for maintenance of any existing structural or treatment control BMP or b) to replace an existing structural or treatment control BMP with new control measures or BMPs meeting the current standards of the city and the municipal NPDES permit. Such requirement shall be included in any sale or lease agreement or deed for such property. The condition of transfer shall include a provision that the successor property owner or lessee conduct maintenance inspections of all structural or treatment control BMPs at least once a year and retain proof of inspection.
2. For residential properties where the structural or treatment control BMPs are located within a common area which will be maintained by the community association, appropriate arrangements shall be made with the association regarding the responsibility for maintenance.
3. If structural or treatment control BMPs are located within an area proposed for dedication to a public agency, they will be the responsibility of the developer until the dedication is accepted. (Ord. 15-O-2678, eff. 6-18-2015)