City of Houston Mayor Pro Tem Dave Martin’s office has supplied ReduceFlooding.com with the Black & Veatch Engineering report on the recommended alternative for adding floodgates to Lake Houston. One key finding immediately jumped out at me that wasn’t in Martin’s press release last week. The recommended gates would have a release capacity that virtually equals the highest release rate of Lake Conroe during Hurricane Harvey.
The Lake Conroe release rate during Harvey maxed out at 79,000 cubic feet per second (CFS).
The eleven tainter gates recommended by Black & Veatch would have a release rate of 78,700 CFS.
New Possibilities, More Certainty
That opens up a world of possibilities. For instance, the City could wait to start releasing water until it knew water was coming downstream from Harvey.
Said Martin, “Once constructed, we can release with a moments notice which gives us great opportunities to coordinate release protocols with the SJRA!!”
Previously, Public Works has been reluctant to release water in advance of a storm because the release rate of the existing gates is so small. They have to start lowering the lake so far in advance of storms that a storm can veer away before it gets here. If it does, that means water has been wasted.
The recommended floodgates should provide much more certainty for operators and avoid waste.
Key Elements of Recommendation
Other key elements of the recommendation include:
- Locating the floodgates in the earthen eastern portion of the dam near the old channel of the San Jacinto River.
- Creating baffles and a dissipation basin downstream from the new gates to break up the flow and reduce water velocity
- “Outdenting” the gates (i.e., building them in front of the current dam)
- A bridge between the two parts of the earthen dam
- Using tainter gates, the same type used at Lake Conroe.
- A 3.5 year construction schedule.
The last point means that if construction started in January, the earliest completion date would be mid-2026.
However, given the need to line up additional funding in the state legislature, 2027 is a more realistic date.
For a complete discussion of the project history, constraints, alternatives, recommended options, construction drawings, rationales, and costs, see the entire 28-page Black and Veatch Report by Chris Mueller, PhD, P.E.
Posted by Bob Rehak on 12/14/22 based on the Black & Veatch Report
1933 Days since Hurricane Harvey