Today, I came across an eye-popping presentation by John Blount, P.E.. Blount served as Harris County’s Engineer for decades. He left his position last year after serving the Engineering Department for 34 years. The presentation discussed how new building regs adopted in 2009 (and later amended) reduced damage rates during Harvey by approximately 20X.
The Harris County Flood Control District’s (HCFCD) final Harvey report found that 154,170 homes flooded in Harris County during Harvey. HCFCD estimated that was between 9-12% of the structures in the County at the time.
Bount’s report, however, pointed out that – at the time of Harvey – 75,000 homes had been built in subdivisions developed in 2009 or later that conformed to the new, more stringent building codes. These homes were in subdivisions that used current infrastructure requirements for drainage and extreme event-flow analysis. Out of those 75,000 homes, only 467 flooded during Harvey, or 0.6%. That’s 20X less than 12%.
But even more impressive, Blount said that not one of those homes suffered substantial damage.
Factors that Made the Difference
After that, Blount’s 22-page presentation gets fairly technical. It deals with regulations that affect:
- Elevation above the 100-year flood plain
- Acceptable types of foundations in flood hazard areas
- Building in floodways including width, depth, bracing and other construction requirements for piers
- Where fill can and cannot be used
- Detention pond requirements
- Coordination with MUDs and Special Districts
- Coastal vs. Riverine Flooding
- Wind resistance
- Elevation above street level and more
For Full Report and an Eye-Opening Experience
Driving around town after reading this report will be an eye-opening experience. Take any one of the factors mentioned above, for instance, elevation above street level.
As I was driving through Aldine last weekend to photograph the new detention basin along Halls Bayou, I was struck by how many homes, businesses, and apartment complexes were built several feet BELOW the street levels.
Page 12 of Blount’s presentation addresses this issue. “If the structure is a single family residence the finished floor shall be a minimum of 12 inches above the highest adjacent natural grade when measured 10 feet from the edge of the slab or 12 inches above the crown of the adjacent street whichever results in the highest elevation.”
Drive down Aldine Bender Road or Aldine Mail Route and look at the driveways that slope DOWN to properties. No wonder so many homes in this area flood.
It’s bewildering why so many surrounding counties and municipalities have resisted upgrading their building, subdivision and flood plain regs.
Posted by Bob Rehak on 3/7/2022 based on a report by the former Harris County Engineer John Blount
1651 Days since Hurricane Harvey