About 300 area residents attended Houston Mayor Pro Tem Dave Martin’s public meeting at the Kingwood Community Center July 8 to receive updates about two of this area’s most critical flood mitigation projects: dredging the San Jacinto River and the Lake Houston Dam spillway expansion.
The meeting consisted of a short briefing on each project followed by breakout sessions located around the room where residents were able to see detailed representations and get answers to their questions from various representatives for each of projects.
The first presentation was the update on dredging presented by Stephen Costello, Houston’s chief recovery officer for overseeing the entire Houston-area Hurricane Harvey recovery. He described the flood mitigation projects including each of the three major dredging areas in the west fork and east fork of the San Jacinto River along with the “mouth bar” removal at the river’s confluence with Lake Houston.
“The dredging along the west fork of the San Jacinto was the very first project that the Army Corps of Engineers did. They moved about 1.8 million yards of material and they actually pumped it over to two disposal sites, one on the east side of Highway 59 and one to the north and west side of Highway 59,” Costello said. As the project developed, it required large pipes laid in the riverbed to carry out the dredged sediment. These and other pipes will also be needed if future dredging is required.
Costello provided detailed maps of the west fork, east fork and “mouth bar” operations and summarized the whole project by noting a total of 4,004,008 cubic yards of material with a removal cost of $222 million was expected by the time it is completed.
The Lake Houston Dam Spillway Improvement update was presented by Dr. Chris Mueller, a vice president with Black and Veatch, the engineering and consulting firm for the project.
“Presently, we can release one foot of water in 24 hours. With the ability of the new gates, we’ll be able to release four feet of water in 24 hours, so that gives us the ability to react to a storm like Harvey,” Martin said. This is a big project and is going to take years to complete because it has a lot of complicating considerations. They include the nature of the dam’s current construction, the realities of its age and the need to manage the “downstream impact” to residents and businesses south of the dam to the Gulf of Mexico.
Mueller described the present dam as one built to impound water rather than to manage its flow. It now has a spillway structure with four small gates which are designed to release water at a rate of 10,000 cubic feet per second. He presented pictures of designs to better manage and increase flow rates when needed by creating a system of new “crest gates” into the overall structure. He provided photos of two similar existing “crest gates” used on dams located in Ozark Beach, Missouri and Cedar Falls, Wisconsin.
“Gates have different widths and different heights, so there can be some changes there, really, to optimize the benefit we can achieve upstream with the gate operations,” Mueller said.
The design phase will take about 12 months to complete. Then officials will need to gain environment clearance and permits for the project, which he said would likely take two to three months. Mueller pointed out that the regulatory process governing dams has had a significant impact on where the new gates can be located, in terms of how long it would take to meet requirements. The decision at this point is to locate them on the west half of the dam, mainly because environmental and permitting requirements can be met much more quickly in terms of months and even years.
Once approved, construction will take 18 months to two years.
Martin noted everything presented in the briefings, including answers to questions asked in the breakouts, would be made available for the public to see on his Houston City Council website, houstontx.gov/council/e.