Updated Stormwater Requirements for Smaller Site Development

Last updated Sep. 07, 2018 - 11:40 am

Following City Council approval, an amendment to the City’s Unified Development Ordinance (TC-2-16) is now in effect. It incorporates stormwater regulation standards for smaller sites undergoing development or redevelopment that were previously exempt, including lots less than one acre used for single family/duplex dwelling or less than half an acre used for any other purpose that exceed new impervious area limits. These sites are now subject to maximum impervious surface limitations based on zoning district. Any proposed project that increases impervious area may be subject to additional review and/or submittal requirements as a result of the ordinance change.

The change to the ordinance is intended to keep waterways healthy and reduce flooding during and following the completion of new development or redevelopment.

News Release: Smaller Site Development to Require Stormwater Evaluation

What You Need to Know

The amended ordinance includes the following requirements:

  • Grandfathered lots and subdivided lots that meet their applicable Use Standards will be exempt from Active Stormwater Control Measures provided they stay under the Zoning District Maximum Percentage of Impervious Surface Coverage;
  • Grandfathered lots include any lot recorded prior to May 1, 2001 and residential lots created by a subdivision of one acre or less in aggregate size approved after May 1, 2001;
  • Development of lots qualifying for an exemption that exceed new impervious limitations are required to either:
    • Demonstrate that post-development volume of stormwater leaving the site is equal to or less than the volume of stormwater leaving the site under the maximum percent impervious limitation (or existing impervious, whichever is greater) for the lot; or
    • Provide a stormwater impact analysis to show that there will be no adverse impact on downstream properties during the 2, 10, 25, 50, and 100 year storm events;
  • Any lot with a detached single-unit living or attached two-unit living home in existence as of November 27, 2016 is entitled to a one-time 400 square foot increase of impervious surface area.
  • Substitution of impervious surfaces is still a qualifying exemption.

Permit & Survey Updates

Check out the FAQs for smaller site development to learn about what permits and surveys may be required prior to and after your project.

Plan Development

View the plan development spreadsheet that reflects the amended ordinance.

TC-2-16 Plan Development Template

Frequently-Asked-Questions (FAQs)

To learn more about the stormwater regulation for smaller site development, view the following FAQs.


If you have any questions about the amended ordinance, please call 919-996-3940 or email

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