Secrecy surrounds current dredging plans for the mouth bar of the San Jacinto West Fork. We know that the Corps will finish removing 500,000 cubic yards next week. However…
Unkowns at This Time
… we don’t know exactly where they are removing sediment, how wide the area is, how deep it is, and whether they will cut a channel through the sediment dam or just shave some off the top.
The Corps’ refusal to divulge plans puts residents in a bind. How can we know whether they have restored conveyance and safety? We must take their word. We don’t even have a post-dredge survey showing us how they intend to leave the river.
Two Prominent Geologist Suggest Objectives
With those caveats in mind, I asked Tim Garfield and RD Kissling what objectives they would set to restore conveyance and safety. Garfield and Kissling are two prominent area geologists who first brought the mouth-bar problems to the public’s attention. Between them, they have more than 80 years of oil field experience at the highest levels, studying river basins around the world.
Here’s how they responded: “Our overriding objectives are simple:
- Restore flow conveyance of the west fork into Lake Houston
- Survey the entire area being dredged for depth upon completion.
- Extend the upstream dredging which ended near Kings Harbor through the mouth bar area. Said another way, don’t make water flow uphill. Eliminate the ramp.
- Continue the 400’ wide, approximately 20′ deep channel past the SMB until it connects into the relict channel where it is 20’ deep or deeper near the FM1960 bridge.
- Develop and implement a plan for regular maintenance dredging.
- Define responsibilities, budget and source of funding for future dredging.
- Define a schedule of regular depth surveys in order to determine where sediments are re-accumulating and to have a better baseline for future storm events.
- Build and utilize 2D- or 3D-models to help guide future dredging decisions.
- Resolve disposal issues. Identify long-term placement areas and potential partnerships with industry.”
Who Will Achieve Desired Results?
These objectives make sense to me. They describe what the river used to look like before the mouth bar set up and contributed to flooding 7,000 homes and businesses. They also describe what we need to do to keep the problem from recurring. If the Corps doesn’t achieve the desired result, I hope the City, Harris County and State can. You can help by urging elected representatives to get FEMA to designate the mouth bar sediment as Category A.
Corps May Share Results When Dredging Complete
According to Congressman Dan Crenshaw’s office, the Corps has finally agreed to share with outside sources the 1D HEC-RAS model it built. Reportedly, the Corps sent a copy of the model and data to Stephen Costello, the City of Houston’s Chief Recovery Officer. Crenshaw’s office is also trying to obtain the Corps’ dredging plans and make them public.
It will be interesting to see how the Corps’ dredging results line up with Garfield’s and Kissling’s objectives.
Posted by Bob Rehak on 8/31/2019
732 Days since Hurricane Harvey