Precast Happens

By Kirk Stelsel

What do fresh produce and precast concrete have in common? More than you might think.

Everyone enjoys fruits and vegetables from farmers’ markets or grocery stores, but few give much thought to the process by which such products are grown. In addition to the sweat equity of the farmer, it typically requires some extra nutrients. In some cases, the manure used for this purpose is stored in precast concrete structures.

Precast in the dairy capital

Wisconsin and dairy products are inextricably linked based on both volume and public perception. Over the years, dairy farms have continued to increase in size. With that comes the need for more infrastructure. In 2013, Dalmaray Concrete Products in Janesville, Wis., saw an opportunity in this growth and began working on approval for a new product for manure storage.

Using its standard T panels – which the company manufactures for bunker and silage storage as well as salt and commodity storage buildings – Dalmaray engineered a manure storage system. With the bunker and silage markets becoming increasingly competitive and increasing farm sizes driving demand for large-scale manure storage solutions, the move made sense.

During the approval process, the Dalmaray team got a lead on a job for a farmer that was evaluating an alternative solution.

“I found out about this job about a year and a half ago,” said Aaron Ausen, vice president of Dalmaray. “We were approached about this when it was a cast-in-place project and we were asked about using precast. Once we got it approved, we approached the farmer about using precast and he was onboard with it because of the cost savings.”

Along the way, Ausen and his team worked closely with Norm Tadt, senior conservation specialist at the Rock County Land Conservation Department. Tadt was the link between the farmer and the precaster and has seen the advantages precast provides with manure storage pits from a previous job. Among the top advantages, according to Tadt, are the elimination of sloped walls, the accompanying reduction of the overall footprint and the time savings.

“The nice thing with the straight walls is the appearance – it’s neat and tidy,” Tadt said. “Precast versus poured-in-place, our largest poured-in-place wall that we have available to us is a 10-foot wall. This gave the farmer the opportunity to go to 12 1/2 feet.

“You get more storage in the footprint by going to that depth. You also have to have some extra capacity for a large rain.”

The pit can hold 2.3 million gallons of manure and from the top of the panels measures 247 feet long by 132 feet wide. Using T panels, Dalmaray reduced the amount of concrete needed by changing the plans from a 10-inch thick wall down to 6 inches at the thinnest point. There are 148 pieces of precast, including standard wall pieces and corner pieces.

The panels include grade 80 structural steel mesh in combination with traditional rebar. This hybrid approach allowed the precaster to reduce the diameter and spacing of the bar to prevent blockage, pockets or imperfections in the walls. Dalmaray also used a mix design it has seen great results from in recent projects.

“We have a new hybrid SCC mix that has a higher flow and makes the product look a lot nicer,” Ausen said. “It uses an old-school mix technique – a Type A water reducer – and combines it with an SCC admix. It gives us a real nice, cohesive mixture that allows us to get a 28-inch-plus spread.

“There are very few bug holes or other discrepancies on the product. It’s a 6,500-psi mix and has been really nice for us.”

Dalmaray installed the panels and has worked closely with the state conservation engineer on the project. Tadt has been pleased with the results and sees the precast concrete method as a growing trend in the county.

“I foresee that we’ll see more as time goes on,” he said. “I think what they’re looking at is a time savings versus poured-in-place. On some sites, it’s difficult to get the concrete pumped to all the corners. The other thing precast gives you is quality control.

“When it’s poured-in-place, trying to get that steel placement and all those types of things exactly where they’re supposed to be can be difficult.”

Superior slurry storage in Canada

Further to the north, Eagle Builders, a precast concrete manufacturer in Blackfalds, Alberta, recently worked on a project for a dairy producer with a similar need, albeit with a unique twist. For this manure storage project, ground conditions dictated that an in-ground solution was not an option, so the only choice was an above-ground slurry storage.

Eagle Builders had worked with the customer previously on a welding shop and a poultry barn. Because of the success of those projects, Eagle Builders was chosen for both the new dairy facility and the waste storage structure.

“This is the first precast waste containment structure we’ve ever done,” said Werner Brouwer, project manager for Eagle Builders. “We designed and quoted a precast slurry storage for them and compared it to a steel one. The precast option was cost effective.

“Steel was their first choice because that was the only option until we created a precast option.”

According to Eagle Builders, the customer is already noticing rusting issues with their existing steel slurry storage and is looking to precast for a longer life span.

The completed project is 200 feet in diameter and has a 3 million gallon capacity. It is comprised of 56 pieces of precast concrete that are 10 feet wide and 20 feet high. Production was completed in just two days. Eagle Builders has been pleased with the results of the project, as has the customer.

“We are on our third building with Eagle Builders and they have been able to innovate solutions on each build,” said the customer, Beiseker Colony. “So making the choice on a precast containment structure versus steel was obvious due to price and longevity.”

What can precast do for you?

The manufacturers that make up the precast concrete industry continually innovate custom solutions to meet the needs of a wide range of customers. Many precasters find themselves altering a standard product line or creating and obtaining approval for an entirely new line on a regular basis. To learn more about what precast concrete can do for you, contact your local precaster by visiting precast.org/find.

Kirk Stelsel is NPCA’s director of communication and marketing.