New 2021 City Of Houston Stormwater Detention Requirements Explained

As of March 31, 2021, projects submitted by developers and engineers have to comply with the 2021 revised City Of Houston stormwater detention requirements.  In January 2021, the City of Houston revised and increased requirements within Chapter 9 of the Infrastructure Design Manual (IDM) how stormwater detention is calculated within the City of Houston, effectively enforced as of March 31. This comes just a year before the city instituted a massive water line repair program after detecting pipeline leaks, signifying a significant focus on infrastructure improvement projects.

Here are the key regulation highlights:

• Single Family Lots of 7500 SF or less disturbing less than 65% of the area = 0.0 acre-ft/acre Detention Rate
• Single Family Lots of 7500 SF or less disturbing more than 65% of the area = 0.75 acre-ft/acre Detention Rate (the previous rate was 0.2 acre-ft/acre)
• Tract of 1 Acre or Less = 0.75 acre-ft/acre Detention Rate (the previous rate was 0.2 acre-ft/acre)
• Tract of 1 to 20 acres = Detention requirement is based on the percentage of impervious cover resulting from the disturbed area on site determined by the following chart:

For tract sizes over 20 acres: Detention is based on the most current version of the Harris County Flood Control District Policy and Procedure Criteria Manual. The typical increase in detention rate would be to .65 acre-ft/acre.

The good news for developers is that the City of Houston also announced the first phase of Houston Incentives for Green Development. Effective December 2020, a tax abatement program allows for reimbursement of funds spent on Green Stormwater Infrastructure for private development (TRUEGRID meets the criteria) over a 10 year period. In other words, you can be paid back for your previous cover area expenses amongst other Green Stormwater Infrastructure development expenses.  Visit http://www.houstontx.gov/igd/ to learn more.

The 100 % pervious TRUEGRID permeable paver system made in Houston from 100 % post-consumer recycled plastic is a key tool to meet new stormwater detention requirements and Green Stormwater Infrastructure Development. Many developers are concerned about the increased cost associated with the changes and using the TRUEGRID system can help offset these increased expenses while meeting the new code requirements.

Call or email us today to review your project to see how TRUEGRID can help mitigate these expenses. 1-855-355-GRID or nwood@truegridpaver.com.