What’s Changed Since Hurricane Harvey?
DURATION 5 minute read
Hurricane Harvey touched down in Harris County more than four years ago. It dropped 1 trillion gallons of water over four days and caused $125 billion in damages – making it the second most costly hurricane to ever hit the U.S.
The storm inspired discussions among local leaders that focused on how to better prepare communities for the next storm. County and city officials quickly moved to update development regulations, with Harris County and the City of Houston making considerable changes to multiple building codes and ordinances since the storm.
From increased minimum elevation requirements to allowing more green infrastructure, the post-Harvey regulatory changes have come in many forms. Some of the changes impacting developers in Harris County the most include:
Revisions to Harris County’s Floodplain Regulations
The first regulatory change to come out of Hurricane Harvey took effect in January 2018 after Harris County approved multiple updates to its Floodplain Regulations.
The regulations apply to unincorporated areas of Harris County, including communities like Cypress and North Houston. Most of the changes address the required elevation of structures in certain floodplains. For instance, before the changes, structures in a floodway or V Zone were required to have a finished floor supported by a posts or pilings foundation that was at least 18-inches above the 100-year floodplain.
Now, the updated regulations require structures in the floodway or V Zone of an unincorporated community to have a finished floor supported by a pier & beam foundation that is a minimum of 36-inches above the 500-year flood plain.
You can find more information about the updated elevation requirements for structures in various flood zones by checking out this cheat sheet put together by the Harris County Engineering Department.
Updates to Chapter 19 of the City of Houston Code of Ordinances
The City of Houston made its first significant regulatory change in response to Harvey in April 2018. In a 9-7 vote, the Houston City Council approved an overhaul to Chapter 19 of the city’s code of ordinance – the code’s first major modifications in more than a decade.
Following the lead of the Harris County Engineering Department, the City of Houston updated the required minimum elevation of a structure’s finished floor. Previous regulations required structures in a floodplain to have a finished floor at least one foot above the 100-year floodplain; however, the updated regulations now require a structure within a floodplain to have a minimum elevation of two feet above the 500-year floodplain.
The overhauled regulations also require compensation for any fill added to reach the new elevation standards, which is known as zero-net fill. Any fill or new build adds to the displacement amount – causing the floodplain width to increase. But by removing land equal to the fill amount, it offsets the flood volumes and helps protect a structure during a flood event.
Confused about these regulations? No problem! Check out our video for a visual explanation of zero-net fill and the city’s other regulatory changes.
The City of Houston Adopts Recommendations from the Redevelopment and Drainage Task Force
Before Hurricane Harvey, the City of Houston created a drainage and development task force to reevaluate the city’s approach to drainage and development, but their efforts took on a greater meaning after the storm. In early 2018, the task force released a report outlining recommended updates to Chapter 9 and Chapter 13 of the city’s Infrastructure Design Manual.
The recommendations focused on three elements: detention, fill and encroachments on city right of ways. Though not all recommendations were adopted, the city updated its Infrastructure and Design Manual with many of them in September 2018.
Some of the changes included:
Houston Public Works Made Significant Changes to its Detention Requirements
Houston Public Works made supplemental changes to the city’s 2020 infrastructure design manual in early 2021 following Atlas 14 hydrologic data adoption. Depending on the tract size and impervious cover, commercial developments in the City of Houston are now required to provide a minimum volume at a rate of 0.75 acre-feet per acre of disturbed area that results in impervious surface.
Under the new rule, tracts less than 1-acre that are not considered a single-family residential lot will have a required detention volume at a rate of 0.75 acre-feet per acre, which is more than triple the previous rate of 0.20 acre-feet per acre. Tracts between 1 and 20 acres will be required to have a minimum detention volume at a rate of 0.75 acre-feet per acre. However, the required rate goes up based on the percentage of impervious cover, with some developments requiring up to 1 acre-foot per acre.
Per the new rule, tracts greater than 20 acres will be subject to the Harris County Flood Control District’s (HCFCD) Policy Criteria and Procedure Manual (PCPM) criteria. HCFCD requires a minimum storage rate of 0.65 acre-feet per acre and will require an Impact Analysis (Drainage Study) with supporting calculations. The analysis may determine a higher minimum storage rate.
You can read the supplemental changes HERE and find more information from our industry expert HERE.
Hurricane Harvey Flood Mitigation and Restoration Projects
Hurricane Harvey caused unprecedented damage to Harris County’s drainage infrastructure. As part of a post-Harvey assessment, the city and multiple organizations embarked on a mission to restore areas damaged by the storm and better protect the community from future flooding events.
Our team has had the honor of helping multiple agencies on post-Harvey restoration and mitigation projects in communities across Harris County. Most recently, our Program Management team is partnering with the Harris County Flood Control District (HCFCD) to create a program to mitigate the flood-prone Cypress Creek watershed through innovative, holistic, and flood resilience efforts.
Our team has also collaborated with the HCFCD on the nearly $10 million slope stabilization and bench sediment removal at Buffalo Bayou Park. Though the park was designed to flood, it suffered an unusually large amount of damage during Hurricane Harvey. Our team designed the three-phase improvement project that included removing sediment along the bayou, stabilizing slope features, and installing preventative measures to prevent future erosion.
From stream restoration to creating flood compliant developments, our team works tirelessly to help improve communities, focusing on resiliency for the future. You can browse our services page to learn more about how we help build communities across Texas. You can also check out our Industry Insights page for more articles on regulatory changes impacting the AEC industry.