Chapter 3.20 STORM WATER FACILITY DESIGN STANDARDS AND DEVELOPMENT REQUIREMENTS

Sections:

Prior legislation: Ords. 1232 and 1234.1.

3.20.010 Design standards.

The following design standards shall apply to the regional storm water facilities:

A. Whitewater River/Coachella Valley Storm Water Channel. Designed and constructed utilizing the SPS/SPF design standard. The 100-year-plus design standard will now be utilized for this facility, and for analyses addressing impacts associated with lands adjacent to this facility. The WWRSC/CVSC is owned, operated and maintained by CVWD.

B. Existing Tributary Regional Facilities (Owned, Operated or Maintained by CVWD Including USBR Protective Works, or Private Entity). Designed and constructed utilizing the SPS/SPF design standard. The 100-year-plus design standard will now be utilized for these facilities and for analyses addressing impacts associated with lands adjacent to these facilities. These existing tributary regional facilities can be owned, operated and maintained by CVWD or by a private entity that has an existing regional storm water facilities agreement with CVWD.

C. Existing Tributary Regional Facilities (Owned, Operated, or Maintained by Private Entity). Designed and constructed utilizing the 100-year storm/100-year flood design standard. The CVWD 100-year-plus design standard shall be utilized for changes to these facilities and for analyses addressing impacts associated with lands adjacent to these facilities. These facilities will continue to be owned, operated and maintained by a private entity.

D. Proposed Tributary Regional Storm Water Facilities. Design shall be based on the CVWD 100-year-plus design standard. CVWD shall assume operation and maintenance of proposed 100-year tributary regional storm water facilities. In the event a developer specifically requests to assume the operation and maintenance responsibility, CVWD shall determine, in its discretion, whether to approve such a request. In the event the request is approved, the requirements for private ownership, operation and maintenance of the proposed regional storm water facilities shall apply as set forth in CVWDC 3.20.060. (Ord. 1234.2 § 1, 2017)

3.20.020 Calculations.

The following factors shall be utilized for calculating the CVWD 100-year-plus design standard for regional storm water facilities:

A. One-Hundred-Year Flood. The 100-year flood should be estimated using long-term streamflow records within the watershed where available. For streams with no gauges or inadequate length of record, the 100-year flood will be determined from rainfall-runoff (hydrologic) modeling. CVWD standards for rainfall depth, depth area reduction factors (DARFs) and guidelines for rainfall-runoff modeling are given within the CVWD Development Design Manual.

B. Freeboard for Incised Channels. An incised channel is one where the adjacent ground elevation is higher than the 100-year flood water surface elevation within the channel. Incised storm water channels shall be designed to convey the 100-year flood with a minimum of three feet of freeboard above the design water surface elevation. CVWD may require additional freeboard based on the size and location of the watershed and the associated flood hazard potential.

C. Freeboard for Leveed Channels. A leveed condition is one where the 100-year flood water surface elevation is higher than the adjacent ground elevation. Levees shall be designed with a minimum of four feet of freeboard from the levee crest elevation to the 100-year flood water surface elevation. CVWD may require additional freeboard based on the size and location of the watershed and the associated flood hazard potential. (Ord. 1234.2 § 2, 2017)

3.20.030 Compliance.

Regional storm water facilities constructed by a developer in compliance with the requirements of Riverside County Ordinance No. 458 shall also meet the design criteria of CVWDC 3.20.010 and 3.20.020. (Ord. 1234.2 § 3, 2017)

3.20.040 Notice.

The developer shall give written notice of the proposed flood control plan in connection with the development to all downstream property owners within a minimum distance of 600 feet from the development’s lower boundary. The general manager may, in his or her discretion, extend this minimum distance as reasonably required by geographic circumstances. The notice shall include a statement that regional storm water facilities are proposed that may affect downstream properties and will be designed and constructed in accordance with Riverside County Ordinance No. 458 and the provisions herein. (Ord. 1234.2 § 4, 2017)

3.20.050 Flood Zone D.

There are areas within CVWD jurisdiction designated as Flood Zone D by the FIA with undetermined but possible risk of flood hazard. In these areas, project specific hydrologic and hydraulic studies are required to determine the flood hazards. The design standards and parameters used should follow those described in CVWDC 3.20.010 and 3.20.020. (Ord. 1234.2 § 5, 2017)

3.20.060 Agreement.

Private ownership of regional storm water facilities will require a recorded regional storm water facility agreement with CVWD defining operation and maintenance responsibilities. The matters to be addressed in such an agreement shall include, but are not limited to, the following:

A. That upon the transfer of the ownership of the regional storm water facilities, the operation and maintenance obligations of the developer shall be assumed by the successor.

B. CVWD will be granted a flooding easement for the discharge and conveyance of storm water flows through the development.

C. The developer and successor will seek neither damages nor indemnity from CVWD based on or related to the design of the regional storm water facilities.

D. CVWD shall have the right of entry upon the real property on which the regional storm water facilities are located to inspect such areas and facilities to determine compliance with CVWD standards. In the event of noncompliance, CVWD may issue a notice of noncompliance which describes the nature of the noncompliance and specifies a period of time within which developer or successor must correct the noncompliance. In the event the noncompliance has not been satisfactorily corrected, CVWD may enter upon the real property on which the regional storm water facilities are located to make corrections which are necessary, expedient or convenient to eliminate the noncompliance, at the cost of developer or successor. (Ord. 1234.2 § 6, 2017)

3.20.070 Existing capacity.

The design standards set forth in CVWDC 3.20.010 for existing facilities shall not be construed to imply that the existing capacity can be diminished by altering the existing cross-section. (Ord. 1234.2 § 7, 2017)

3.20.080 Authority.

The general manager, or his/her authorized designee, is hereby authorized and directed to take all actions necessary to implement, impose and otherwise enforce the policies adopted by way of this chapter including but not limited to revising Section 8 of the CVWD Development Design Manual entitled “Design Criteria – Stormwater Facilities.” (Ord. 1234.2 § 9, 2017)