No Longer Bursting At the Seams

What do you do when the transfer station serving your growing community reaches capacity and there's no place else to go? If you're the South Utah Valley Solid Waste District, you renovate your existing facility to increase its capabilities.

Rehabbing transfer stations is a relatively new concept. As landfills closed during the past decade, there was an explosive growth of transfer stations that, for the short-term, were designed to handle their communities' projected waste streams. Then, as the waste industry's whirlwind of mergers began, some older, less efficient, urban-area transfer stations closed. Others continued to handle a relatively stable daily volume of waste.

However, waste planners in some of the fastest growing regions of the country now are facing the predicament of how their transfer stations will handle a waste stream that grows exponentially each year, exceeding original design and plan predictions. When the South Utah Valley Solid Waste District was presented with this problem in late 1996, it decided to rehab its facility.

The South Utah Valley Solid Waste District originally was formed in 1990 to service the south end of Utah County and the cities of Mapleton, Provo, Salem, Spanish Fork and Springville, Utah. The District owns and operates the Bayview landfill near Goshen, Utah. To provide economical waste transfer for its municipal and commercial waste haulers, in 1991, the District constructed the Springville Transfer Station.

The Springville facility originally was designed to handle approximately 175 tons per day, according to John Dempsey, vice president of HDR Engineering Inc., Omaha, Neb., which worked with the District to build and renovate the station. But as community waste volumes increased, the facility, which serves municipal and commercial customers and is open to residents on the weekends, began to show signs of fatigue.

"We were approaching the maximum that the compactor could handle," says Richard Henry, District manager, who noted the equipment was wearing down and the tipping floor needed repairs. "When the station opened, it handled less than 200 tons per day compared to today's capacity of approximately 400 tons per day. Today, approximately 200 vehicles come in each day. We send out about 20 transfer trailers to the landfill and have handled as much as 700 tons and 31 transfer trailers in one day."

To prepare for the future and extend the existing facility's life, Henry says expansion was the best option. The District considered building another transfer station, but the existing site's location was ideal and finding another site would have been difficult.

"Most of the city's population is located at the north end of the area that we service," Henry says. "There really wasn't a better place to put it."

Thus began the transfer station rehab.

Assembling a Plan Obviously, rehabilitating its facility required carefully reviewing the District's limitations and envisioning the transfer station's future potential. "The first thing we had to do was really assess what our problems were and what possibilities were available," Henry says. "It's harder to increase the size of the tipping floor if it is undersized." If that's the case, another site, if one is available, might be a better choice, he says.

Other considerations were costs and efficiency. One of the ways efficiency is improved is by incorporating technology into the rehabilitation, Dempsey suggests. "You want to look at appropriateness of technology," he says. "Is the approach or the technology you're using optimal? In today's competitive environment, optimization really is the key."

For example, a quarter of a transfer station's cash flow likely goes toward capital construction, Dempsey says. As a facility matures, capital is reduced because the fixed debt is retired, whereas operations and hauling costs increase. Hauling costs typically represent 50 percent of a facility's expenses. However, by simply changing the technology, you can reduce hauling costs by 10 percent, he notes.

The District's transfer station was unique; it originally incorporated a single pre-load compactor that was loaded from the side instead of from the traditional top-load method due to some site, timing and cost constraints. The facility also housed a second hopper bay with shallow base 6-foot grade separations that could be used to top load when the compactor was down.

Reviewing its needs, the District selected HDR to provide engineering support. The consulting engineering firm was familiar with the operation and had worked with the District since 1990. HDR immediately began to determine what rehabilitation was necessary.

"We looked at their facility and the fairly dramatic growth - almost triple the tonnages," Dempsey says, "and evaluated the station's ability to receive vehicles, store waste and throughput not only the tonnages it was receiving but also the quantities it was projected to receive during the next 10 to 15 years."

Several challenges became apparent. First, the facility was too small to handle future growth. Second, the backup method of loading, lift and load was no longer reliable based on tonnage volumes.

Thus, establishing a reliable backup system that could handle the tonnages and provide efficient output became the focus, Dempsey says.

Because building expansion was not an option, Dempsey decided to increase the station's capacity by adding a second compactor and rehabilitating the first compactor for a backup.

"[The District] really needed to make sure that it could put all the waste through the building fairly efficiently," Dempsey says. "That's what drove a decision to remove the top loading bay and install a second compactor. The unit was wearing out as a result of pushing through two and three times the tonnages."

Additionally, the deteriorated floor in front of the hopper needed to be replaced. The District decided to fix the floor and concurrently, the decision was made to install a new side load compactor.

Keep the Trash Moving Keeping the flow of solid waste moving through the facility during reconstruction was critical. Much of the rehab work was performed during the winter when the tonnages were lighter. Nevertheless, the compactor and flooring were out of service for some time, and alternative arrangements were made.

"We didn't have a compactor in place for about eight weeks - that was the worst of it," Henry recalls. To accommodate this challenge, the District temporarily used a lift and top-load system and worked long hours to get the job done.

"Normally, we accept trash from 7 in the morning until 6 in the evening - 11 hours," Henry says. "We continued to accept trash during those hours, but it would take until 10 p.m., or even later sometimes to get it all out. It was a slow process of pushing trash, getting it in the loader, lifting it up and dumping it into the trailers. It was handled primarily with longer hours and a little bit of extra manpower."

Once the floor was completed, the old unit was removed and a new compactor, purchased from SSI Shredding Systems, Wilsonville, Ore., was installed. The backup bay subsequently was modified to accommodate the old compactor that became the station's standby or overflow system.

The rehab, which occurred within the past 18 months, means the transfer station has the capacity to handle a yearly average of 500 tons per day.

Henry credits the rehabbed facility's success to his consulting engineers, which helped the District avoid potential pitfalls and stumbling blocks.

"A good engineering firm can perform many of the technical inspections, contract supervision and project oversight tasks that most agencies don't have the staff to handle," he says. "They can make a lot of difference. If you're busy running the facility, you don't have time to stand out there and make sure the contractor is doing the job."