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HomeMy WebLinkAbout1768 ORDINANCE N0. 1768 AN ORDINANCE OF THE CITY COUNCIL OF THE CITY OF PALM SPRINGS, CALIFORNIA, AMENDING SECTION 8.70.100 OF THE PALM SPRINGS MUNICIPAL CODE FOR THE PURPOSE OF ESTABLISHING ON-SITE STORMWATER RETENTION REQUIREMENTS. City Attorney Summary This Ordinance establishes on-site stormwater retention requirements for new development projects within the City pursuant to an RWQCB Order. WHEREAS, the City has adequate legal authority by and through the Palm Springs Municipal Code and the Riverside County Code to implement and enforce the legal requirements related to on-site stormwater retention imposed upon the City to date under Regional Water Quality Control Board (RWQCB) Order No. R7-2008-0001, consistent with the requirements set forth in the regulations of the Clean Water Act, 40, Code of Federal Regulations 122.26(d)(2)(i)(A-F), and to the extent permitted by State and Federal Law and subject to the limitations on municipal action under the California and United States Constitutions, and WHEREAS, adoption of an implementing ordinance is a requirement of the National Pollutant Discharge Elimination System (NPDES) program as an alternative for the City in lieu of establishing additional Site Design Best Management Practices (BMP), and it will further allow the City to eliminate developer requirements under the Riverside County Water Quality Management Plan (WQMP), such as the aforesaid Site Design BMP, stormwater treatment, and hydromodification; and WHEREAS, adoption of the implementing ordinance will result in financial savings to developers and the City as relates to the development and review of WQMP. THE CITY COUNCIL OF THE CITY OF PALM SPRINGS DOES HEREBY ORDAIN AS FOLLOWS: SECTION 1. Section 8.70.100, Chapter 8.70, Title 8 of the Palm Springs Municipal Code shall be amended to delete the existing provisions thereof in their entirety, and replace said provisions as follows: 8.70,100 On-Site Stormwater Retention (a) When required by the City Engineer, the applicant shall submit hydrology and hydraulic calculations, and drainage area maps to the City, to determine the quantity of stormwater runoff generated by a site or tributary to it, as well as its effects on the site, and to upstream or downstream properties. Erosion and sediment transfer studies, and other supporting data may be required as determined by the City Engineer. Ordinance No. 1768 Page 2 (b) Limits of inundation on the subject property during condition of specified storm frequencies may be required to be delineated on the grading plan, along with the submittal of supporting calculations. (c) The use of streets for flood control and drainage purposes may be prohibited by the City Engineer if the use of the streets is not in the interest of the public health, safety, and welfare. If the City Engineer permits the use of streets for flood control and drainage purposes, the 10-year storm frequency design discharge shall be contained between the tops of curbs or asphalt concrete dikes, and the 100-year storm frequency design discharge shall be contained within the street right-of-way. The tributary drainage area for which an applicant is responsible shall extend to the centerline of adjacent public streets. (d) On-site stormwater retention requirements for new development and redevelopment projects in the City of Palm Springs are defined as follows: (i) A required on-site stormwater retention system shall have sufficient capacity to contain the volume of stormwater runoff representing the difference between the existing (undeveloped) condition and the proposed (developed) condition resulting from the most conservative duration (1-hour, 3-hour, 6-hour, or 24-hour) 100-year storm (hereafter defined as the "project storm"). This volume of stormwater runoff is defined as the "incremental volume of stormwater runoff'. (ii) For single family residential in-fill lots, if a drainage area is 70% or more developed, individual single family residential projects located on an in-fill lot will be exempt from the on-site stormwater retention requirements, except in the case of hillside lots. A "drainage area" is defined as the area within the boundaries of the separate drainage areas defined on the Master Drainage Plan for the Palm Springs Area (either "North", "Central", "South", "East", "Southeast", or "Eagle Canyon") or as may be determined by the City Engineer. Front yards shall drain to the street unless constrained by the overall lay of the land. Hillside development shall be designed to retain on-site the incremental volume of stormwater runoff. (iii) For non-residential (commercial or industrial) in-fill lots, if a drainage area is 70% or more developed, non-residential (commercial or industrial) construction projects two (2.0) acres or less in size, will be exempt from the on-site stormwater retention requirements, except in the case of hillside development. Hillside development shall be required to retain on-site the incremental volume of stormwater runoff. (iv) If an existing retention or disposal site is available and has adequate capacity to accept the incremental volume of stormwater runoff, an on-site retention system may be eliminated if a drainage system is provided which adequately conveys the incremental volume of stormwater runoff to the existing retention or disposal site as approved by the City Engineer. Such a drainage system shall include a provision to fully address disposal of nuisance water to the satisfaction of the City Engineer. Ordinance No. 1768 Page 3 (v) On-site retention areas shall be clearly shown on site plans to demonstrate compliance with these stormwater retention requirements. Site plans shall be designed to ensure that adequate area exists for on-site retention, minimizing the use of parkway and setback landscaped areas exclusively as retention areas. Parkway and setback landscaped areas shall balance the need for retention and community/project design. As a general rule, a maximum of 40% to 50% of any parkway and setback landscape area may be designed as a retention area. Retention basin side slopes and depth shall be subject to the approval of the City Engineer. (vi) In the design of retention facilities, the maximum percolation rate shall be two inches per hour. The percolation rate shall be considered zero unless the applicant provides site-specific data that indicates otherwise. (vii) The site shall be graded to allow stormwater runoff in excess of the incremental volume of stormwater runoff to flow out of the site through a designated overflow outlet and into the historic drainage relief route. Stormwater runoff historically received from adjoining property shall be received and retained on-site, or passed through to the historic downstream drainage relief route. (viii) No site design shall cause any increase in flood boundaries, flood levels, flood duration or flood occurrence in any off-site area. (e) The civil engineer or design professional responsible for preparation of the plans shall certify that the building pads to be created through any proposed grading are free from inundation from stormwater runoff from the project storm, and to provide floodplain elevations and widths, sheet flow depths, floodway elevation and widths (in accordance with the Palm Springs Municipal Code Chapter 8.68 for Flood Damage Prevention), and any other data required by the City Engineer, or by any applicable county, state, or federal flood protection or insurance program or requirement. SECTION 2. If any section or provision of this Ordinance is for any reason held to be invalid or unconstitutional by any court of competent jurisdiction, or contravened by reason of any preemptive legislation, the remaining sections and/or provisions of this ordinance shall remain valid. The City Council hereby declares that it would have adopted this Ordinance, and each section or provision thereof, regardless of the fact that any one or more section(s) or provision(s) may be declared invalid or unconstitutional or contravened via legislation. SECTION 3. The Mayor shall sign and the City Clerk shall certify to the passage and adoption of this Ordinance and shall cause the same, or the summary thereof, to be published and posted pursuant to the provisions of law and this Ordinance shall take effect thirty (30) days after passage. Ordinance No. 1768 Page 4 ADOPTED THIS 3RD DAY OF FEBRUARY, 2010. �! /'�' �� STEPH N P. POUGN T, MAYOR ATTEST: ?MES THOMPSON, CITY CLERK____._ STATE OF CALIFORNIA ) COUNTY OF RIVERSIDE ) ss. CITY OF PALM SPRINGS ) I, JAMES THOMPSON, City Clerk of the City of Palm Springs, California, do hereby certify that Ordinance No. 1768 is a full, true, and correct copy, and was introduced at a regular meeting of the Palm Springs City Council on the 20th day of January, 2010, and adopted at a regular meeting of the City Council held on the P day of February, 2010 by the following vote: AYES: Councilmember Foat, Councilmember Mills, Councilmember Weigel, Mayor Pro Tern Hutcheson, and Mayor Pougnet. NOES: None, ABSENT: None. ABSTAIN: None. mes Thompson, City Clerk / 2-1 Lo f City of Palm Springs, California a3 e