Post-Construction Stormwater Management

Improving Water Quality Through Quality Design

This measure emphasizes the reduction or elimination of pollutants to the municipal separate storm sewer system that may come from post-construction runoff after new development and redevelopment projects. The term post-construction is used to describe runoff from a site with impermeable surfaces, such as buildings, roads, and parking lots that remain after construction ends. If unchecked, increased impervious surfaces associated with development will increase stormwater volume and degrade water quality, which can harm Ankeny's streams and ponds.

The best way to mitigate stormwater impacts from development is to use practices to treat, store, and infiltrate runoff onsite before it can impact downstream water bodies. By requiring site designs that reduce imperviousness, increase infiltration, and provide water volume storage, water quantity and water quality can be improved.

This is achieved through the following actions.

Enforce a Post-Construction Site Runoff Control Policy Ordinance

This addresses control of runoff from building activities after construction is complete. This includes the promotion of stormwater detention and retention, grass swales, bio-retention swales, riparian buffers, and proper operation and maintenance of these facilities.

Implement Site Plan Review of Post-Construction Runoff Controls

This implements procedures and acceptance criteria for the review of controls for NPDES-permitted construction sites.

Inspect Runoff Control Devices

This addresses the inspection and review of stormwater control devices and structures for proper maintenance. It includes providing educational material to landowners.

Implement a Watershed Assessment Program & Comprehensive Land Use Plan

This outlines the measures to be implemented which reduce flooding, reduce erosion in ditches and streams, improve water quality and reduce the degradation of habitat for fish and wildlife.