Pomona Municipal Code § 74-311 Findings

This article shall be known as the "City of Pomona Low Impact Development (LID) Ordinance" and may be so cited.

(Ord. No. 4185, § 1, 6-2-2014)

The City of Pomona finds that:

(1) Waterbodies, roadways, structures, and other property within and downstream of the city are at times subject to flooding.

(2) Land development alters the hydrologic response of watersheds, resulting in increased stormwater runoff rates and volumes, increased flooding, increased stream channel erosion, increased sediment transport and deposition, and increased non-point source pollutant loading to the receiving waterbodies and the beaches.

(3) Stormwater runoff produced by land development contributes to increased quantities of waterborne pollutants.

(4) Increases of stormwater runoff, soil erosion, and non-point source pollution have occurred as a result of land development, and have impacted the water resources of the San Gabriel River Watershed and the Santa Ana River Watershed.

(5) Increase stormwater runoff rates and volumes and the sediments and pollutants associated with stormwater runoff from future development projects within the city will, absent proper regulation and control, adversely affect the city's waterbodies and water resources, and those of downstream municipalities.

(6) Stormwater runoff, soil erosion, and non-point source pollution can be controlled and minimized by the regulation of stormwater runoff from development.

(7) Adopting the standards, criteria, and procedures contained in this Article and implementing the same will address many of the deleterious effects of stormwater runoff.

(Ord. No. 4185, § 1, 6-2-2014)

The provisions of this article are adopted pursuant to the Federal Water Pollution Control Act, also known as the "Clean Water Act," codified and amended at 33 U.S.C. 1251 et seq. The intent of this article is to enhance and protect the water quality of the receiving waters of the United States in a manner that is consistent with the Clean Water Act (and acts amendatory thereof or supplementary thereto), applicable implementing regulations, and the Municipal NPDES permit (as defined below, and any amendment, revision, or re-issuance thereof). It is the purpose of this article to establish minimum stormwater management requirements and controls to accomplish, among others, the following objectives:

(1) Lessen the water quality impacts of development by using smart growth practices such as compact development, directing development towards existing communities via infill or redevelopment, and safeguarding of environmentally sensitive areas.

(2) Minimize the adverse impacts from stormwater runoff on the biological integrity of natural drainage systems and the beneficial uses of waterbodies.

(3) Minimize the percentage of impervious surfaces on land developments by minimizing soil compaction during construction, designing projects to minimize the impervious area footprint, and employing low impact development (LID) design principles to mimic predevelopment hydrology through infiltration, evapotranspiration, and rainfall harvest and use.

(4) Maintain existing riparian buffers and enhance riparian buffers when possible.

(5) Minimize pollutant loadings from impervious surfaces such as roof tops, parking lots, and roadways through the use of properly designed, technically appropriate best management practices (BMPs, defined below) including source control BMPs such as good housekeeping practices, LID strategies, and treatment control BMPs.

(6) Properly select, design and maintain LID and hydromodification control BMPs to address pollutants that are likely to be generated, reduce changes to pre-development hydrology, assure long-term function, and avoid the breeding of vectors.

(7) Prioritize the selection of BMPs to remove stormwater pollutants, reduce stormwater runoff volume, and beneficially use stormwater to support an integrated approach to protecting water quality and managing water resources in the following order of preference:

a. On-site infiltration, bioretention and/or rainfall harvest and use.

b. On-site biofiltration, off-site ground water replenishment, and/or off-site retrofit.

(Ord. No. 4185, § 1, 6-2-2014)

The following terms, phrases, words, and derivatives shall have the meaning defined below:

Basin plan means the Water Quality Control Plan, Los Angeles Region, Basin Plan for Coastal Watersheds of Los Angeles and Ventura Counties, adopted by the Regional Water Board on June 13, 1994 and any subsequent amendments.

Beneficial use means the existing or potential use of receiving waters as designated by the Los Angeles or Santa Ana Regional Water Quality Control Boards in their respective basin plans for the county.

Best management practices or BMPs are practices or physical devices or systems designed to prevent or reduce pollutant loading from stormwater or non-stormwater discharges to receiving waters, or designed to reduce the volume of stormwater or non-stormwater discharged to the receiving water.

City means the City of Pomona.

City engineer means the city engineer for the City of Pomona.

Conveyance facility means a storm drain, pipe, swale, or channel used to collect and direct stormwater.

Design engineer means the registered professional engineer responsible for the design of the stormwater management plan.

Detention system means a system which is designed to capture stormwater and release it over a given period of time through an outlet structure at a controlled rate.

Development means any construction, rehabilitation, redevelopment or reconstruction of any public or private residential project (whether single-family, multi-unit or planned unit development); industrial, commercial, retail and other non-residential projects, including public agency projects; or mass grading for future construction. It does not include routine maintenance to maintain original line and grade, hydraulic capacity, or original purpose of facility, nor does it include emergency construction activities required to immediately protect public health and safety.

Director means the director of public works for City of Pomona.

Discharge means any release, spill, leak, pump, flow, escape, dumping, or disposal of any liquid, semi-solid, or solid substance.

Disturbed area means an area that is altered as a result of clearing, grading, or excavation.

Engineered site grading plan means a scaled drawing or plan and accompanying text prepared by a registered engineer or landscape architect which shows alteration of topography, alterations of watercourses, flow directions of stormwater runoff, and propose stormwater management and measures which are prepared to ensure that the objectives of this article are met.

Grading means any stripping, excavating, filling, and stockpiling of soil or any combination thereof and the land in its excavated or filled condition.

Hardscape means any durable, pervious or impervious surface material, including paving for pedestrians and vehicles.

Hydromodification means the alteration of a natural drainage system through a change in the system's flow characteristics.

Impervious surface means a surface that does not allow stormwater runoff to slowly perchlorate into the ground.

Low impact development or LID means technologies and practices that are part of a sustainable stormwater management strategy that controls, retains or filters stormwater and urban runoff on site.

Maximum extent practicable or MEP means the extent to which the city can reduce the discharge of pollutants in stormwater runoff. MEP requires selecting and implementing effective BMPs, and rejecting applicable BMPs only where: (a) other effective BMPs will serve the same purpose; (b) the BMPs would not be technically feasible; or (c) the cost would be prohibitive. Factors considered include, but are not limited to:

(1) Effectiveness: Whether the BMP addresses a pollutant of concern;

(2) Regulatory compliance: Whether the BMP complies with storm water regulations, as well as other environmental regulations;

(3) Public acceptance: Whether the BMP has public support;

(4) Cost: Whether the cost of implementing the BMP has a reasonable relationship to the pollution control benefits achieved;

(5) Technical feasibility: Whether the BMP is technically feasible, considering soils, geography, and water resources.

Municipal NPDES permit means California regional water quality control board, Los Angeles Region, Order No. R4-2012-0175, NPDES Permit No. CAS004001 waste discharge requirements for municipal separate storm sewer system (MS4) discharge within the coastal watersheds of Los Angeles County, except those discharges originating from the City of Long Beach MS4, and any amendment thereto or re-issuance thereof.

Municipal separate storm sewer system (referred to herein as "MS4"), means a conveyance or system of conveyances (including roads with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, manmade channels, or storm drains):

(1) Owned or operated by a state, city, town, borough, county, parish, district, association, or other public body (created by or pursuant to state law) having jurisdiction over disposal of sewage, industrial wastes, stormwater, or other wastes, including special districts under state law such as a sewer district, flood control district or drainage district, or similar entity, or an Indian tribe or an authorized Indian tribal organization, or a designated and approved management agency under section 208 of the CWA that discharges to waters of the United States;

(2) Designed or used for collecting or conveying stormwater;

(3) Which is not a combined sewer; and

(4) Which is not part of a publicly owned treatment works (POTW) as defined in 40 CFR Section 122.2.(40 CFR Section 122.26(b)(8)).

Natural drainage system means any unlined or unimproved (not engineered) creek, stream, river, or similar waterway.

Non-storm water discharge means any fluid discharge to the storm drain system and/or receiving waters that is not composed entirely of storm water but may not necessarily be an illicit discharge.

NPDES or National Pollutant Discharge Elimination System means the national permitting program for issuing, modifying, revoking and reissuing, terminating, monitoring and enforcing permits, and imposing and enforcing pretreatment requirements, under Clean Water Act (CWA) §307, 402, 318, and 405. The term includes an "approved program."

Mandated by Congress under the Clean Water Act, the NPDES stormwater program is a comprehensive two-phased national program for addressing the non-agricultural sources of stormwater discharges which adversely affect the quality of our nation's waters. The program uses the National Pollutant Discharge Elimination System (NPDES) permitting mechanism to require the implementation of controls designed to prevent harmful pollutants from being washed by stormwater runoff into local water bodies.

Pollutants of concern means chemical, physical, or biological components of stormwater that impair the beneficial uses of receiving waters, including those defined in Section 502(6) of the Federal Water Pollution Control Act ("Clean Water Act," 33 U.S.C. Section 1362(6)), and incorporated by reference into California Water Code Section 13373.

Public works department means the City of Pomona public works department.

Receiving water means a "water of the United States" (as defined in 33 C.F.R. section 328.3(a)(7)) into which waste and/or pollutants are or may be discharged.

Retention means a holding system for stormwater, either natural or man-made, which does not have an outlet to adjoining watercourses or wetlands and in which water is removed through infiltration and/or evaporation processes.

Runoff means any runoff including stormwater and dry weather flows from a drainage area that reaches a receiving water body or subsurface. During dry weather it is typically comprised of base flow (either contaminated with pollutants or uncontaminated) and nuisance flows.

Sediment means mineral or organic particulate matter that has been removed from its site of origin by the processes of soil erosion, is in suspension in water, or is being transported.

Standard industrial classification (SIC) means a classification pursuant to the current edition of the standard industrial classification manual issued by the executive office of the President of the United States, Office of Management and Budget, and as the same may be periodically revised.

Storm drain means a conduit, pipe, swale, natural channel, or man-made structure which serves to transport stormwater runoff. Storm drains may be either enclosed or open.

Stormwater means runoff that occurs as the result of rainfall.

Stormwater quality design volume (SWQDv) means the runoff generated by the greater of either:

(1) The 0.75-inch, 24-hour rain event; or

(2) The 85th percentile, 24-hour rain event, as determined from the Los Angeles County department of public works 85th percentile precipitation isohyetal map.

Urban runoff means surface flows, other than stormwater, emanating from development.

Water quality design storm event means any of the volumetric or flow rate based design storm events for water quality BMP's identified in the national pollutant discharge elimination system municipal stormwater permit for the county of Los Angeles.

(Ord. No. 4185, § 1, 6-2-2014)