At a Nov. 14 community meeting, officials provided updates on several projects targeting the creek from the $2.5 billion bond referendum passed by Harris County voters last August.
The first project involves implementing channel improvements on South Mayde Creek between Fry and Greenhouse roads and building a new bypass channel to carry stormwater from east of Greenhouse to the Addicks Reservoir.
Project Manager Jonathan St. Romain said the project is undergoing preliminary engineering—including surveying, environmental work and hydrologic modeling—which is expected to last through spring 2020.
The district already owns about 300 feet of right of way along the part of the channel slated for widening, St. Romain said.
“That’s a good thing,” he said. “We can do channel widening in this area without going after additional right of way. There’s a lot more room in the right of way we already own to excavate out on both the left and right sides of the channel.”
However, the bypass channel would be built on land owned by the Army Corps of Engineers, which means additional permits will be have to be acquired, St. Romain said. One particular hurdle involves demonstrating that the bypass channel will not bring any more sediment into the Addicks Reservoir, he said.
“We have had constant coordination with the [Army Corps], lots of back-and-forth in determining what is going to be involved with those permits,” he said.
Richard Long, who works in the Houston Project office for the Army Corps’ Galveston District, where he oversees operation of the Addicks and Barker reservoirs, was also in attendance at the Nov. 14 meeting. He said there are several important questions that still need to be answered.
“If they can address the environmental issues and they can address the concerns that we may have with the impacts of the project, there is no reason we would not be able to allow them to do this project,” Long said.
A bypass channel would help stormwater travel through the system faster into the Addicks Reservoir, Long said.
"When you put a bypass channel in, it allows the floodwaters coming down the channel to get into government property faster and lowers the peak of the water level upstream of government property significantly so that they can pull some of the homes out of the 100-year flood plain," he said.
The bypass channel poses several additional challenges, St. Romain said, including having to intersect with a separate tributary into South Mayde Creek and having to cross Groeschke Road, which could necessitate a bridge.
At the time the bond referendum was passed, the cost estimates for both channel improvements and bypass came in at $10 million. Once implemented, the improvements are projected to lead to a reduction in peak water elevation of roughly 1.3 feet during a 100-year storm, St. Romain said. The benefits will be seen in the residential communities in the area between Greenhouse and Fry roads, he said.
A separate bond project discussed at the Nov. 14 meeting involves building two regional detention basins in an open area along the creek east of Fry Road. The basins would be used to temporarily store stormwater before slowly allowing it to drain back into South Mayde Creek, St. Romain said, which would help reduce structural flooding.
Details on where the basins would be located are still to be determined, St. Romain said.
“We have a nice generic oval through the region because we’re looking at a couple of 60-acre or so properties that are open land right now,” he said.
An eastern basin would hold 578 acre-feet of stormwater, or roughly 188,300 gallons. A western basin would hold 404 acre-feet of stormwater, or 131,600 gallons. Preliminary results suggest the basins would lower peak water elevation by 0.5 to 1 feet during a 100-year rainfall event.
The preliminary engineering and public input process will continue through 2019, and a detailed design effort could begin by next summer depending on how fast the district can obtain right of way, St. Romain said. Officials estimate the project could cost $16 million.