River Oaks Wastewater Treatment Plant

Due to increasing maintenance and operation expenses at the Dale Mabry Wastewater Treatment Plant, the county expects to retire the plant.

To prepare to end operations at the 40-year-old plant, the county is installing a six-mile stretch of 24-inch and 36-inch reclaimed water pipeline transmission main, and a new pump station to transfer wastewater flows from the Dale Mabry plant’s location to the Northwest Regional Water Reclamation Facility.

The pump station, as well as reclaimed water tanks, will replace the Dale Mabry plant, which will be demolished, likely in early 2017.

Once the wastewater facilities at the Dale Mabry site are removed, it will leave a majority of the site as a green space, which is likely to become a county park.

The Dale Mabry Wastewater Diversion Project is one of three components of the larger, $240 million Northwest Hillsborough Wastewater Consolidation Project.

The other phases involve expanding the Northwest facility to accept and treat additional wastewater flows, as well as retiring the River Oaks Wastewater Treatment Plant.

The Dale Mabry portion of the project costs approximately $35 million.

Officials say the entire program will improve treatment efficiency, reduce power costs and minimize future rate impacts.

“It’s kind of like an old air conditioner. When you replace your old air conditioner, it’s like, ‘Wow, I really saved a lot of money,’” said Thomas Rawls, program manager of the Northwest Hillsborough Wastewater Consolidation Project. “When we transfer that flow to the new plant, it’s like you’re getting better motors, better energy savings.

“Everything’s more efficient.”

Barring any delays, the Rawls said the entire project should be completed by December—ensuring the pumps, pipeline and plant all work in conjunction with one another.

“We have to make sure the (Northwest) plant can absorb that (water) flow because we use a biological treatment system…there’s actually living organisms that treat our wastewater, and you don’t want to shock them,” Rawls explained about the flow transfer. “It’s like you’re sending them a new type of food, if you want to call it.”

The county expects the entire Northwest Wastewater program to save the county approximately $80 million over the next 20 years. Water rates will not rise for residents, officials say.

“As soon as we start transferring that (water flow), the county’s saving money,” Rawls said.

Rawls referred to the project as “the perfect storm,” for beginning construction this year, due to the county’s good credit rating and bond capacity. Plus, the county was staring down the barrel of “$10 (million)-$20 million” in repairs alone at the Dale Mabry plant site.

“It’s like an old car — you’re either going to junk it, or you’re going to rebuild it make it a pristine car,” the project manager explained. “We’ve got the fiscal ability, the county’s administration is behind it, the citizens are behind it, and it’s just a good mesh of everything.

“Five to 10 years ago — in the middle of that recession — it wasn’t the best time to go out and do this,” he said.

Construction crews are currently installing transmission pipelines along Gunn Highway between the Veterans Expressway and Lynn Turner Road—which should wrap up in the next few months.

With drills going underneath major intersections at Brushy Creek and the Veterans Expressway, there have been a small section of lane closures.

“We’re doing a directional drill that goes down 40 feet underground…and comes up on the other side,” said Rawls. “We don’t want to affect all the traffic in those big intersections, but we’ll have to close some of the median. It’s better than cutting through the intersection and disrupting all that traffic.”

Rawls said the project’s construction has “stayed pretty true” with its timelines, especially since the county is using a “design-build” form of project delivery, where both the designer (McKim & Creed Engineering) and contractor (Westra Construction) are working hand in hand.

“If they come across a problem out there, they have a team of engineers and experts out there that can get together, figure out the issue and keep moving, so there’s less impact on the community,” Rawls said. “It’s not going to linger on for years and years.”

During the winter months, Rawls noted it’s much easier to lay pipe into the ground, because there’s not as much rain.

“We can properly compact the (piping), and backfill it while it’s drier,” he explained. “We kind of held off during the holidays, but we’re hitting it hard now. We’re picking it up full steam.”

Published February 3, 2016