The City of Phoenix has enacted a Stormwater Ordinance in order to establish minimum stormwater management requirements and controls to protect and safeguard the general health, safety, and welfare of the public residing in watersheds within this jurisdiction. The City of Phoenix is the permitting authority for all land disturbing activities and requires the land owner to maintain all on-site stormwater control facilities and all open space areas (e.g. parks or “green” areas) required by the approved stormwater control plan. The City of Phoenix will only provide construction permits to projects that establish a plan to manage stormwater runoff occurring during the construction process. The City of Phoenix, under the NPDES program, also has the authority to inspect properties for noncompliance and can issue a notice of violation (NOV) for any deficiency or infraction onsite. Property owners are responsible for the maintenance of any stormwater facilities or practices located on the property. The City of Phoenix has the authority to inspect stormwater facilities and practices in order to ascertain that they are properly maintained and functioning.
This Stormwater Management Plan (SWMP) was created in response to the Arizona Pollutant Discharge Elimination System (AZPDES) General Permit AZG2016-002. The SWMP is the principal means in which Maricopa County (County) has recorded programs and policies to demonstrate full permit compliance. Under the general permit, the County must implement actions and activities that demonstrate compliance with permit requirements. These actions are called Minimum Control Measures (MCMs) and include:
The County has developed Best Managing Practices (BMPs) for each MCM. Each MCM and their corresponding BMPs are outlined and detailed in Section 6.0 of this SWMP.
Existing Maricopa County regulations require that developments receive and retain stormwater volume generated by a two-hour, 100-year precipitation event. Retention basins are required to be located not less than 25 feet from septic systems. Runoff that has been retained onsite must be disposed of within 36 hours by percolation, dry wells, or drainage into an approved drainage way, not to exceed pre-development flows. Disposal of stormwater is considered essential for vector control. The drainage regulations also contain language designed to ensure stability and prevent erosion in hillside developments. An inventory of all post construction stormwater structures is maintained. This inventory fluctuates at properties and land are annexed over time.
It is essential that maintenance be considered during the planning, design and construction of drainage facilities. Maintenance is provided so that the facilities can function as they were originally designed and constructed, and so that the service life of the facility is maximized. Common maintenance problems associated with drainage facilities include growth of unwanted vegetation, debris accumulation, sedimentation, erosion, scour, soil piping, soil settlement and structural damage. Culverts and bridges are to be designed to avoid impacts to existing sediment transport conditions. Provision for permanent drainage facility accessibility, including access for maintenance equipment into channels and culverts, is necessary for regularly scheduled maintenance activities.
All drainage facilities owned and/or operated by private entities, including Homeowner's Associations, shall be properly maintained to promote performance of the drainage facilities consistent with the original design intent.
Maricopa County Stormwater Management Plan