We learned a little bit more this week about the next phase of dredging. Several graphics (below) released by the Corps summarize modifications to the Emergency West Fork Debris Removal Project.
What We Confirmed and Learned
We confirmed that:
- Great Lakes, the prime contractor on the original job, will be the only contractor on the Corps portion of the contract extension
- Great Lakes will pump sediment all the way upstream to Placement Area 2
- The Corps intends to dredge 500,000 cubic yards in the area of the mouth bar.
We learned that:
- The original contract contingency allotment of approximately $3.5 million was used up, most likely by additional sediment washed downstream during floods in December, January, February, May and June.
- Callan, the subcontractor for phase one, has approximately 83,000 cubic yards to dredge due to modification of the original contract.
- Dredging an additional 500,000 cubic yards will cost another $17,085,861
- The FEMA/Corps portion of the dredging should finish by December 6, 2019
- Demobilization and cleanup will take until Jan. 22, 2020
- This is FEMA mission assignment SWD-30
- Great Lakes started dredging the mouth bar on June 25th
- Great Lakes will dredge a wide area but not go all the way to the FM1960 bridge.
Corps Releases Summary of Project and Extension(s)
I compiled the information above from a PDF developed by The Army Corps. They released it on July 9.
To calculate the depth of dredging in that blue area to the right, I simulated the outline in Google Earth and found that it roughly equals 500,000 square yards. That means if they dredge this whole area, they will reduce the river bed by approximately 3 feet. The area already averages 2-3 feet deep. That means the river will be roughly 6 feet deep through this reach when the Corps finishes its portion of the job.
However, upstream, Callan is dredging to a depth of 22.5 feet. Thus, creating a continuous gradient along the river bottom would require dredging approximately another 16 feet deeper in the same area…and that wouldn’t even get you to the FM1960 bridge. Also, note the gap in the graphic between where Callan will finish its portion of Phase One and Great Lakes will start mouth bar dredging.
It is unclear at this point who will dredge the rest of the material that needs to be removed to restore conveyance of the West Fork. Neither the City, County, nor State have yet announced their plans. We don’t know:
- Where they will dredge
- How deep they will go
- Where they will place the material
- How much it will all cost, or
- When they plan to do it.
In the meantime, here are two dramatic sequences of photos plus a video submitted by readers this week. They show what the start of mouth bar dredging looked like from the air and water.
Carolyn Daniel Mouth Bar Shots from Airplane Landing at IAH
Carolyn Daniel submitted these shots of the mouth bar and dredging activity taken from her airplane window while on a landing approach to Bush Intercontinental Airport.
Franz Willett Drone Shots Courtesy of BCAeronautics
Franz Willette runs a company called BCAeronautics that uses drones in mapping, inspections, roofing analyses, site surveys, and 3D modeling. He did not have clouds to contend with and could shoot safely from a much lower elevation. Willette is FAA certified.
Kendall Taft Video
I hope to post updates weekly on this project. So readers, please help. Submit your images through the submissions page of this web site. My thanks to Carolyn Daniel, Franz Willette, BCAeronautics and Kendall Taft.
Posted by Bob Rehak on 7/13/2019 with help from Carolyn Daniel, Franz Willette, BCAeronautics and Kendall Taft.
683 Days since Hurricane Harvey