News Feature | June 5, 2019

Houston's $1.76B Treatment Plant To Be Among Nation's Largest

Peter Chawaga - editor

By Peter Chawaga

Houston has had more than its fair share of water issues in recent history, most notably a water quality crisis following Hurricane Harvey in 2017. Now, the city is making progress on a gargantuan drinking water treatment plant (WTP) expansion to change that narrative — at least on the drinking water side.

As the largest public works project in the city’s history, the facility expansion is just one aspect of a larger plan to secure a sustainable water supply.

“The $1.76-billion plant entails more than 1 million [cubic yards] of earthwork, and 215,000 [cubic yards] of structural concrete,” per Engineering News-Record. “It is one component of an overall $3.5-billion program that will also include a $350-million project to transfer water 23 miles from the Trinity River into Lake Houston and two sets of water transmission lines, costing $1.25 billion, to move the water throughout the region.”

The project is primarily to address Houston’s growing population and the toll it is taking on groundwater withdrawal, which has caused neighborhoods to sink. The plant expansion is expected to reduce groundwater use by 80 percent by 2035.

“From 1906 to 2016, all areas of Houston experienced some subsidence, and some neighborhoods sank as much as 10 ft,” according to Engineering News-Record. “Since 2013, areas northeast of downtown have dropped almost 1 ft, according to the Harris-Galveston Subsidence District, which regulates groundwater withdrawals and has mandated the reduction of groundwater use. The trend cannot be reversed, but it can be stopped.”

The Houston area relies on the region’s aquifers for 70 percent of its water, per Engineering News-Record. It has a difficult time recharging aquifers because of the layers and soils there. With the new plant, Houston will be able to treat raw water from Lake Houston more quickly. Ultimately, the project will give Houston the ability to treat 448 MGD by 2025.

“The water will be pumped from a 30,000-sq-ft pump station on Lake Houston through two 108-in. steel pipes to the plant,” Engineering News-Record reported. “From there, a coagulation, flocculation and sedimentation process will remove the bulk of the inert solids and about 50 percent of the total organic carbon in the raw water. The plant will use plate settlers to minimize the sedimentation basin footprint… The settled water will be treated with ozone for primary disinfection and taste- and odor-removal purposes.”

Of course, none of these treatment efforts will help Houston with potential flooding from stormwater. That potential remains a concern for the city as well.

“Houston has been taxed by many rain events in recent years and [Houston Public Works Director Carol] Haddock said the city is still in recovery mode after Harvey’s floods engulfed much of Houston in August 2017,” per Houston Public Media. “She said there are thousands of people who still haven’t gotten back into permanent housing.”

To read more about major drinking water projects, visit Water Online’s Asset Management Solutions Center.