Council approves repairs, change order for wastewater plant



Liberty Hill is spending $270,000 to replace the 18 membrane bioreactor modules at the wastewater treatment plant after they were damaged due to a failed screen intended to keep larger items out of the plant.

“This is to replace all 18 of the MBR modules that suffered some damage due to a failure at the headworks screen at the plant,” said Aaron Laughlin with Steger Bizzell Engineering. “The screen failed and really did a lot of damage to the membranes.”

Nine membranes have already been replaced, while the others were repaired, but Laughlin said they need to be replaced as well.

Due to the nature of the damage to the modules, they are not covered under warranty.

The screen failure allowed items through the system that clogged and damaged the membranes. Laughlin said no one has determined exactly what caused the screen to fail. In repairing the screen, gravel, some wire and even a piece of PVC pipe was found in the screen.

“It’s anyone’s guess how that got there, but most likely those rocks and gravel got into a force main during some construction and when the pumps kicked on it pushed all that gravel up into the head box and those rocks are not things a screen can handle,” Laughlin said.

The screen was replaced under warranty last summer.

In addition to the approval of the purchase of the MBR modules, the Council approved change orders to the scope of work for the plant expansion, approved in July.

“Since that (approval of the scope of work) we’ve had several scope changes to the work,” Laughlin said.

Those changes include a permanent access walkway to the headworks unit, a late requirement from Texas Commission on Environmental Quality, an additional 2 millimeter secondary headworks drum screen, the expansion of the on-site admin building, a re-screening system and odor control measures.

“The secondary headworks unit will be a 2 millimeter screen – our exiting one is 3 millimeter – and it is recommended,” Laughlin said. “What we’re proposing is to run the effluent through the 3 millimeter screen unit and from there run it through the 2 millimeter screen after that. With this drum screen we’re proposing there is really no physical way possible for screenings to bypass this unit unless the steel drum itself suffers catastrophic damage to it.”

The five listed items would add $925,000 to the expansion construction costs, or just over 10 percent overall. The additional engineering costs would be $99,500, bringing the total to $789,600. The engineering services during construction would go up slightly to $305,000, bringing the total increase to $1 million at $10,897,100 overall.

There was discussion, however, over whether to move forward with the change orders for the original 1.2 million gallon per day expansion, or to consider revamping that plan to create 1.6 million gallons per day in new capacity.

The alternative proposal would increase capacity over the original expansion plan by 400,000 gallons per day, but would also add nearly $3 million to the cost.

“This is something the Mayor and City staff asked me to look into about a month ago,” Laughlin said. “Instead of building a single 1.2 million gallon per day plant, we would build two 800,000 gallon per day that are identical to the first one and give you an extra 400,000 gallons per day capacity.”

Mayor Rick Hall mentioned in discussion that on benefit to going with two additional 800,000 gallon per day plants the replacement parts on all three units would be the same, potentially leading to less need for keeping replacement parts on hand.

City Administrator Greg Boatright advocated for sticking with the original plan.

“I feel like the 1.2 (million gallon per day) is where we need to be,” he said. “That was my original stance and I still feel that way simply because of cost constraints. I think with the changes we have made in the scope of work to the original plan we can handle that, but if we go beyond that I feel like we are going to step outside of what we just went through with our utility rate study. I feel like we’ve got a good design on the 1.2 and we’re way down the road on that.”

By sticking to the original plan, the City expects to be able to go out for bid in April. A change to the expanded option would mean probably a 60-day delay, according to Laughlin.

The Council opted for the change orders to the original plan versus increasing the overall capacity and going back to the drawing board.

“I think the 1.2 is well-planned, it is something we can afford,” Boatright said.

EDC approvals
The Council approved a pair of measures voted on last week by the Economic Development Corporation (EDC), allowing the expansion of the facade grant program and signing off on a new branding campaign.

The facade grant program will be expanded beyond the previous downtown district limits to include street-facing facades along SH 29 from the high school in the west to Ronald Reagan Blvd. In the east, along RR 1869 from SH 29 north to US 183 and south from SH 29 to Mourning Dove.

The program also stipulates that other properties can be considered on a case by case basis.

The program would allow business applicants to be reimbursed for 50 percent of the cost of the improvements up to $5,000 upon completion of an approved facade renovation project. The current program covers only the designated downtown area and has assisted 11 businesses through the grant program.

The branding contract with Hot Dog Marketing is for $7,385 includes development of a marketing booklet, and four different one-page front and back flyers that will be specific to different industries. A slide deck for Powerpoint presentations would also be developed.

The EDC will get 250 copies of the 20-page booklet and 100 of each of the four flyers, as well as the PDF files to have more printed later.

Valuing trees
A pair of protected trees in the newest section of Liberty Parke under development stirred discussion on how they might be saved rather than letting the builder remove them and pay the $45,000 fee to the City.

According to the Liberty Hill Unified Development Code, any hardwood tree more than 19 inches in diameter requires Planning and Zoning and subsequent City Council approval before it can be removed.

The two trees – one a 50-inch Live Oak, and the other a 40-inch Live Oak – are impacting three total lots on the site, and Planning and Zoning recommended allowing the builder to pay the fee and remove them.

The mitigation fee is calculated on a two-to-one ration, meaning the removal of the 90 inches of trees would require the builder to pay for 180 inches at $250 per caliper inch.

“The $45,000 would be placed in our tree fund,” said Director of Planning Sally McFeron. “Those funds are used to plant trees in other parts of our city such as parks.”

Because the homebuilder had indicated they may be able to spare one of the trees, Council members decided to ask McFeron, Boatright and Hall to meet with the builder and discuss ways in which one or both trees might be saved.

The issue was tabled pending that discussion.