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      ​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​Stormwater Post-Construction Program

      Post-construction stormwater controls are used to limit surface runoff and reduce pollutant loadings and include features such as retention/detention basins, drywells, green stormwater infrastructure, and stormwater pretreatment devices.​

      While these devices are not new to development projects, new post-construction requirements in the City of Phoenix's Phase I Municipal Separate Storm Sewer System (MS4) permit were added by the Arizona Department of Environmental Quality.  Effective July 1, 2022, the City of Phoenix has started implementation of a program to inventory, track, inspect, and confirm adequate maintenance of ​post-construction stormwater controls for public and private projects of one acre or more.  ​

      Contact us at postconstruction.storm@phoenix.gov​, call 602-534-7130 (voice), or 7-1-1 (TTY)​.

      Program Overview

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      This will allow the City to maintain compliance with the Arizona Department of Environmental Quality's (ADEQ's) Arizona Pollutant Discharge Elimination System (AZPDES) program.  This post-construction program is not a substitute for any current application, permitting, inspection, or approval process.

      This program applies to all new public and private development and redevelopment projects completed on or after June 30, 2022. The following criteria will be used to determine inclusion in this program:

      • Project is one (1) acre or greater in size
      • Construction application was submitted or after June 30, 2022
      • Project contains permanent post-construction controls (detention basin, dry well, green infrastructure, etc.)

      Please note, this program is still in development. Updates will be posted to this site as they become available. Below is a summary of anticipated program requirements. 

      Inspections

      Applicable projects will undergo a site inspection within one (1) year after construction completion.  Additional inspections may be required in the future to confirm feature functionality.

      Maintenance

      Maintenance requirements under the current City of Phoenix Stormwater Policies and Standards Manual and applicable Phoenix City Code in Chapter 32 remain in effect.  

      Starting March 1, 2024, developers or property owners (or designee) will be required to complete a site-specific maintenance plan for post-construction stormwater controls and include in the Grading & Drainage or Paving Plan Submittal. The plan shall include the site conditions, maintenance frequency and practices, and inspection criteria for each stormwater post-construction control. The City developed a manual template to streamline development and approval of this plan, TRT 000132, Operations and Maintenance Plan Template. Find the current version linked below in the resources.

      Program Updates 

      As of March 1, 2024, all development and redevelopment projects are required to complete and submit a site-specific maintenance plan with their Grading & Drainage and/or Paving Plan Submittal if they meet the following specifications:

      • Project results in one (1) acre or greater of disturbance
      • Project has at least one (1) post-construction control

      Please refer to the City developed standardized template for use, TRT 00132, Operations and Maintenance Plan Template, linked below in the resources.  A Word version of this document is available by contacting staff at postconstruction.storm@phoenix.gov​.

      Operations and Maintenance

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      All stormwater features owned and operated by private entities, including Homeowner's Associations, shall be properly maintained to promote performance consistent with the original design intent. (City of Phoenix Storm Water Policies and Standards Section 3.9.5) It is especially important during monsoon season. Taking proactive steps to help stormwater get to its intended location without causing excessive erosion, flooding or other damage can save on costly repairs and help preserve water quality. Below are some helpful hints but are not intended to be an exhaustive list to help you maintain these extremely important features.

      Dry Wells: Check that stormwater dissipates after a storm event. Standing water should not be present after 36 hours. This prevents damage to your structures and helps prevent mosquito breeding.

      Culverts, Catch Basins, and Drainage Grates: Water needs to flow through these devices during a storm event. Ensure all structures are free from trash or other debris.

      Retention Basins: Look for signs of erosion on the slopes of the basin. Verify that the retention basins have not filled with silt or other materials that prevent them from retaining water. 

      Drainage Channels: Remove debris, silt, and/or plant material that will prevent the devices of conveying water.  ​

      Resources