Ocala wetlands park still dealing with sinkholes

More than a dozen sinkholes — including four that opened Friday — continue to plague the Ocala Wetland Recharge Park. The trouble has been persistent, though expected, since June, when the city started pumping water into the retention cells.

Project developers say it’s a normal part of the process, though it did force city officials to cancel the grand opening last fall. In August, the state temporarily halted pumping due to the sinkholes.

“You’re saturating areas that haven’t been saturated before. You can imagine the water weight on top of that soil. The designers think it should start subsiding,” said Jimmy Lopez, the city’s project manager for the park.

The park is located near the former Pine Oaks Golf Course in the 2200 block of Northwest 21st Street in Ocala. The park’s core function is to serve as a water recharge area. Already treated wastewater is pumped into the cells, which are semi-porous, allowing the water to slowly percolate through the soil and eventually making its way back to the Floridan aquifer.

The slow percolation, along with water plants in the cells, helps to further purify the water. The park also include walking tracks and observation points for residents.

But before any of it opens, engineers must create an artificial wetland that allows just enough water through the soil without undermining the limestone layer beneath and causing a collapse.

It’s a tall order.

Even when fixing the sinkholes, workers use semi-porous material to allow for percolation.

“This is not like a sinkhole that opens in a parking lot. We’re not grouting them. We want to allow for some permeation,” Lopez said. ’The reason they picked this ground is because it does have porosity in it so (the water) will filter through and recharge.“

Oscar Tovar, the city’s deputy engineer, said all of the previous sinkhole repairs at the park continue to hold.

“It’s going to stop. We just don't know exactly when,” Tovar said.

Since June, it's been a similar process. The city pumps treated wastewater into the cells. When a sinkhole opens, workers drain the cell, repair the sinkhole, and then pump water into the cell again.

The most recent sinkholes broke open on Friday. Four sinkholes swallowed some 2 million gallons of water. The largest of the four sinkholes measured 15 feet in diameter. Friday’s openings hit Cell 3, and earlier this week a smaller sinkhole opened in Cell 2, causing the loss of about 500,000 gallons of water. Officials had hoped the number and size of the sinkholes was slowing down, but they have no way of knowing for sure.

“There are ways to map the voids beneath the surface, but that is very expensive,” Lopez said.

For now, the plan is to continue allowing the sinkholes to open up and then repair them.

Tovar said the $6 million grant from the St. Johns River Water Management District that funded the project also covers the sinkhole repairs. Once the project is finished, maintenance and repairs fall to the city.

Lopez said they will start planting vegetation in the cells in May. The plants should also help stabilize the soil. Even if there is another sinkhole, the plants can live out of water for about two weeks. It usually takes a few days to repair a sinkhole.

They hope to open the park by June.

Treated wastewater from the city already irrigates public areas and has industrial uses, but falls just short of drinking water standards. Once up and running, the 55-acre park is expected to filter up to 5 million gallons of treated wastewater every day back into the aquifer.

— Contact Carlos E. Medina at 867-4157 or cmedina@starbanner.com