Second Dredge Starts Dredging
It’s official. There are now two dredges actually dredging on the West Fork. Dredge #2, owned and operated by Great Lakes Dredge and Dock, moved downriver from the command site on October 16.
Getting 2-foot Pipe Through Water One Foot Deep
However, the company had not yet reached placement area #2 with the pipeline. Great Lakes had to dredge their way upstream through water less than one-foot deep in places to get to the placement area with five miles of pipeline that is 2 feet in diameter.
Next Steps: Patches and Pressure Testing
After reaching the placement area with pipe, Great Lakes then had to test it. During testing, dredgers slowly increase pressure in pipe as they look for leaks. The most common place to find leaks is at the joints, but sometimes they need to replace entire sections of pipe. The dredgers then make repairs in the water from pontoons loaded with backhoes and welding equipment. Backhoes bring the pipe up from the bottom of the river and position it in the welding machines.
After that, the dredging company had to test the booster pumps and throttles as they started them up. They also perform dye tests to calibrate velocity measurements. This helps ensure that water in each stage is moving at the same rate of speed. Great Lakes and its subcontractor Callan Marine will each use up to three booster pumps to keep five miles of sediment-laden water moving upriver to their respective placement areas.
While dredge #1, which started the same process on September 20 is diesel, dredge #2 is electric. Electric dredges run quieter, but take longer to warm up. As my source said, “An electric dredge slowly heats up the equipment to drive the moisture out; water and electricity don’t mix well.”
Now Working 24/7 Until Completion
With all those steps complete, dredging is now in full swing. By this weekend, both dredgers will be working 24/7 until completion.
To help jumpstart dredging, Great Lakes hired Callan Marine as a subcontractor. Callan had equipment available earlier and started this same process on September 20. The diagram below shows how both companies plan to work together.
Great Lakes will start at the western edge of the project area and work its way to the middle. Meanwhile, Callan, which started in the middle will work its way to the project’s end point – east of the West Lake Houston Parkway Bridge (by Chimichurri’s).
Callan will send its spoils to placement area #1 while Great Lakes will send its to placement area #2.
No News Yet on Next Phase of Dredging
When City of Houston representatives including City Council Member Dave Martin returned from Austin two weeks ago for a high level meeting about the need to remove the mouth bar, hopes were running high. Decisions makers needed only an environmental survey and a placement area before the mouth bar project could proceed. Reportedly, they had reached agreement in principle on all other requirements including funding. However, the City has made no announcements yet about either the survey or a third placement area.
It took 3.5 months for contractors to fully mobilize for the current project. If FEMA, the Corps, the State, and the City can lock down phase two before mid-April, 2019, taxpayers have a chance to save the cost of another mobilization/demobilization – about $18 million.
It would also save precious time. Without having to remobilize, dredgers would have a chance to cut a channel through the mouth bar before the onset of next hurricane season.
What About River Grove Boat Launch?
Cutting a channel through the side bar at River Grove will probably be the last thing Great Lakes does as part of this phase of dredging. Dredgers are concerned about boater safety and worry that opening the channel now will increase the number of boats on the river and the chance of accidents.
Posted on October 25, 2018 by Bob Rehak
422 Days since Hurricane Harvey