The wastewater treatment plant in the Ohio city of Newark played a key role in putting a contaminated former industrial site to use.

Once home to an aluminum processing plant, the site was subject to severe restrictions, even after remediation. Eventually, American Electric Power (AEP) OnSite Partners and the city collaborated to give the brownfield a new purpose.

AEP developed a 1 MW solar array, and the city signed a long-term agreement to use the power at its wastewater treatment plant nearby. While such solar installations are not unusual, this case presented unique challenges. The 66-acre site had been covered with mounds of aluminum dross, the waste product from Newark Processing, which had operated dry mills, wet mills and furnaces. The company went bankrupt in 1997.

Remediation plans

In 2005, a plan was drawn up to stabilize the severely eroding banks of the Licking River at the site. The Army Corps of Engineers completed the work in 2009 with a $2.8 million grant from the Ohio Environmental Protection Agency. For the rest of the remediation, Newark received a $2 million Clean Ohio Revitalization Fund grant.

“The Army Corps of Engineers graded everything basically level,” says Mark Mauter, the city’s development director. The riverbanks had been covered with large rocks to prevent erosion, and the area where aluminum was processed and waste product stored was covered with a geotextile fabric, which was then capped with soil and planted with vegetation. “We trucked in enough subsoil to cover 40 acres with 2 feet of soil,” Mauter says.

Limited options

At that point, the city had a cleaned-up brownfield that looked like green space, but there were few development options. “We are not allowed to penetrate that cap, even with something like tree roots,” Mauter says.

“When we knew we weren’t able to put any kind of structure there, we started talking about a solar array. We thought that with the wastewater treatment plant only a 1/2 mile away and with that plant being the city’s biggest electricity user, maybe something could work out.”

But even the idea faced problems. For one, the city didn’t want to own and operate a solar power system. For another, solar panels need support structures. The only way to support the array would be to use concrete anchors on the surface. Nothing happened right away. “We had companies approaching us, but they wanted us to own and maintain it,” Mauter says.

Waiting ultimately worked. In 2015, AEP OnSite Partners offered to build, own, and maintain a solar array; the city would just have to buy the power.

Concrete poured

The supports for the solar panels are anchored by concrete disks about 3 feet in diameter and 18 to 24 inches high, poured in place. AEP has used similar ballasted systems before, but the Newark project was different.

“The concrete tub structure used in Newark is a newer type of ballasted system versus what we have used before,” says Tammy Ridout, manager of media relations for AEP. “There is a slight increase in the cost, but we found it to be cost-effective because there are other efficiencies. For example, it is safer and more efficient for workers to pour concrete into a tub than to move large concrete blocks into place.”

The 3,312-panel system occupies 5 acres. Although AEP OnSite Partners maintains the area around the panels, Newark must provide reports to the Ohio EPA twice a year to show that there is adequate vegetation on the site’s total 40 acres to prevent erosion.

Power to the grid

The solar array will produce 25 to 30 percent of the plant’s electricity and, at times, it will produce more than the plant can use. For example, on one sunny day last fall, the solar array was producing 780 kW, while the plant was using 450 kW. “Our whole plant was running entirely off the solar array for about six hours,” says Bryan Curry, plant superintendent. Because the plant has net metering, excess power can be sold to the utility grid.

In the past, plant operators had considered generating electricity from biogas, but the economics never worked out. The 8 mgd (design) has three anaerobic digesters (Walker Process Equipment, A Div. of McNish Corp.). The methane is scrubbed in a pressure swing adsorption unit (Guild Associates) made and sold to the local gas company.

Long-term savings

Curry believes the solar project will work out well economically. The price for electricity coming off the solar array is comparable to the local utility rate, but there could be significant savings over time. “It’s hedging against future increases in electric rates,” Curry says. “We have a 25-year agreement at a rate fairly close to what we pay right now. We took a little bit of a gamble that electricity prices will continue to go up.

“I’m hoping that each month we’ll have some savings. As utility prices go up faster than the price for solar, we’ll be saving more and more every year. It’s not a huge savings, but the use of the brownfield really makes it nice.”