Bugs and bubbles

Wastewater treatment plant expansion well underway

Let’s be honest. It’s not pretty. We’d rather not talk about it. But there’s arguably no more vital a service the city provides its residents than the collection and treatment of wastewater.

Main Street Widening Project aside, Phase I of the city’s upgrades to the Wastewater Treatment Plant (WWTP) on East Lake Highlands represents one of the biggest current construction projects in The Colony. Projected to cost $19.8 million, the project will increase the plant’s daily treatment capacity in order to keep up with all the growth taking place in the city.

In 2015, the plant treated approximately 1 billion gallons of wastewater. That’s up from 981 million in 2013. Its current daily capacity is 3.8 million gallons. By mandate of the Texas Commission on Environmental Quality, a municipality must begin design of plant expansion when it reaches 75 percent capacity. Construction must begin at 90 percent capacity.

Having recently met those milestones, construction on the plant began in early 2016. The WWTP expansion project budget consists of construction costs, engineering services during construction, project administration, and quality assurance and control.

“All of these different components come together to ensure success of the project,” said Evan Groeschel, Project Management Analyst for The Colony Public Works Department. “Obviously there’s a lot of moving parts. This is the biggest job I’ve worked on in the eight years I’ve been with the city.”

All of the city’s wastewater enters the facility through a main line before being funneled into two “trains” (A and B), for treatment. The expansion project consists of adding a third train (C) to the plant, which will increase capacity to 4.5 million gallons per day.


Surrounded by the signs and supplies of major construction, an aeration basin and clarifier treats wastewater. It is one of two structures that make up trains A and B at the Wastewater Treatment Plant.

Each train has two main processes that treat and clean the water. One process is called aeration, in which air is infused into the wastewater in such a way that it enhances the ability of naturally-occurring microorganisms to break down contaminants.

“The aeration basin is where the biological process of breaking down oils and fats takes place,” said Albert Pardo, an on-site engineer for Carollo Engineering, the city’s design and project management contractor. “And the bubbles control the way the bugs work.”

The second process along the train happens in the clarifier, which is a mechanical means of sedimentation that “allows all the solids to come down before the water on top moves on to further treatment and then out into the lake,” Pardo said. (Click here for more detail about the entire treatment process.)

The two processes are combined into one structure for trains A and B, but they have been separated into two larger components for the new train. “It’s the same setup, just on a much bigger scale,” Pardo said. The train C basin, for example, is a massive concrete structure with a capacity of 1.5 million gallons and multiple compartments for specialized treatment.


The new aeration basin will hold 1.5 million gallons and is compartmentalized for a variety of treatments.

In addition to the C train, enhancements to the overall facility in Phase I include a new splitter structure to help evenly distribute the flow to the three trains; modifications to the existing treatment trains; a new effluent meter system to measure what’s going out to the lake; and a new chemical backup treatment system in the event the biological system fails, said Daemeon Stovall, Chief Operator for the WWTP.

Not to mention all the excavation, electrical work and piping required to, eventually, integrate the new components into the system. To top it off, all of this construction is taking place in a facility that must maintain operational integrity 24 hours a day, seven days a week.


A new clarifier is being constructed alongside the new aeration basin. The two treatment components have been separated as part of the new train “C” at the Wastewater Treatment Plant.

“Our primary goal is maintaining treatment during the process in order to continue meeting the state’s requirements,” Stovall said. “If they have to shut down something for construction, we have to provide bypass systems. We can’t stop the wastewater from coming in. We can’t stop treatment. There is no acceptable limit of contamination the state will allow us to have.”

Safety and security is another big subject, Groeschel said. The plant has to stay secure at all times. Added construction traffic was a little disruptive, too, but they’ve adjusted to it. “Constant communication is the key so everyone knows what everyone is doing. That really mitigates a lot of risk with the operation,” he said.


Project Management Analyst Evan Groeschel flips through one of the many large binders he keeps with information about the WWTP project.

Given the size and significance of the project, quality-control redundancies are built in. For example, all of the concrete poured is tested at two separate labs for strength and viability.

“Without those redundancies, you create a weak point – and it’s typically not something you can just fix down the road,” Groeschel said. “We have a responsibility to protect the investment our citizens are making in this facility. You can’t take even a little break in terms of ensuring quality-control standards are being met.”

Phase II of the WWTP expansion will extend the facility’s treatment capacity to 6.1 million gallons per day and take place when the city reaches buildout.

“It’s a good thing we’re doing this now because more and more new development is coming online every day,” Groeschel said. “This is all fueled by the city’s growth, both now and in the future.”