Stormwater Management Program

Many cities, or municipalities, across the nation operate “combined sewer systems” which are designed to convey discharges of both storm water runoff and wastewater from houses and businesses to a treatment plant where that water is treated prior to being discharged to any “waters of the United States” (such as a wash, stream, lake, river, ocean, or any of their tributaries). In contrast, the City of Surprise, like many municipalities in the valley, operates a “municipal separate storm sewer system” or MS4, which is designed to convey discharges that are composed entirely of storm water, and is separate from the wastewater sanitary sewer system. It is important to note that MS4 discharges flow UNTREATED directly to our community retention basins, city parks, washes and rivers.
Storwater Management Program
Picture illustrating a sanitary sewer system discharge on the left and storm water MS4 discharge on the right (courtesy of STORM).

This Storm Water Plan (also referred to as a Storm Water Management Program [SWMP] has been prepared by the City of Surprise as required by the Arizona Department of Environmental Quality’s (ADEQ) Arizona Pollutant Discharge Elimination System (AZPDES) General Permit Number AZG2002-002. The Permit was issued by ADEQ effective on December 19, 2016 and will expire on September 29, 2021.

The SWMP describes the policies and procedures the City implements to reduce, to the maximum, extent practicable (MEP), pollutant discharges to and from the small municipal separate storm sewer system (MS4). The overall goal of the program is to ensure to the MEP that discharges from the MS4 do not cause or contribute to exceedances of surface water quality standards. 

As required by the Permit, the SWMP addresses the six minimum control measures (MCMs):

  • Public Education and Outreach
  • Public Involvement/Participation
  • Illicit Discharge Detection and Elimination
  • Construction Site Stormwater Runoff Control
  • Post-Construction Stormwater Management in New Development and Redevelopment
  • Pollution Prevention/Good Housekeeping for Municipal Operations

Current storm water related ordinances are detailed in the following City’s Municipal Codes:

Chapter 10 Article II Division 3 miscellaneous restrictions (Code 2007, SS 6.04.170) - Addresses the removal of pet feces in public ways and places. Pet waste carries diseases and harmful bacteria. Uncontained pet waste can mix with rainwater and cause storm water pollution.

Chapter 117 Stormwater Management Section 117-3. Development Regulations. (Code 2007, SS 15.20.050) – Addresses what is considered to be a “public nuisance.” Standing water in storm water structures (i.e. retention basins, catch basins, drywells, etc.) often are sources for the proliferation of mosquitoes and other nuisance insects. Standing water becomes an issue if it does not drain within a 36-hour period.

Chapter 34 Offenses and Miscellaneous Provisions Article V. Offenses involving public peace and order Section 34-110. Flooding of Streets. (Code 2007, SS 9.16.120) – Addresses the flooding of streets. Discharging water to the public city streets can impact storm water quality by collecting and transporting contaminants to storm water structures. In addition, discharging to the streets can create a standing water issue and be a violation of other City ordinances.

Chapter 117 Stormwater Management Section 117-2. Plan and Report. (SS 15.20.020, SS 15.20.030, SS 15.20.040) & Title 16, Chapter 20 (SS 16.20.050) – Addresses design requirements. The proper sizing of a retention basins and evaluation of subsurface soils is necessary in designing a retention system that operates properly.

Chapter 117 Stormwater Management Section 117-5. Right of city to drain basin. (SS 15.20.050, SS 15.20.060, SS 15.20.070, SS 15.20.080, SS 15.20.090) – Addresses poorly draining retention basins. Retention basins should naturally drain within a 36-hour period in order to eliminate them as a source for the proliferation of mosquitoes and other nuisance related issues.