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Bringing phosphate mines back to nature in southeast Hillsborough County

 
Project manager Janie Hagberg, 53, stands in front of the pump being used to circulate water to carve out land and recreate a creek in Balm Boyette Scrub Preserve. There used to be a creek in the area before the land was used for phosphate mining in the 1960s. [ALLIE GOULDING   |   Times]
Project manager Janie Hagberg, 53, stands in front of the pump being used to circulate water to carve out land and recreate a creek in Balm Boyette Scrub Preserve. There used to be a creek in the area before the land was used for phosphate mining in the 1960s. [ALLIE GOULDING | Times]
Published July 3, 2019

BALM — Engineers working to return phosphate land to nature in southeast Hillsborough County are recreating an old stream though a new process called hydraulic carving. The method is similar to the kid's game of using a garden hose to form a river in the sandbox, only on a life-size scale.

"That definitely was the inspiration,'' said John Kiefer, principal water resources engineer at Lakeland-based Wood Environment & Infrastructure Services, Inc., who came up with the process. Kiefer was watching his then-4-year-old son, Nolan, create a hose-powered mini-river in his sandbox, he said, and it triggered thoughts about using water instead of excavating equipment to build streams.

Later, he led a research team that studied the dynamics of Florida streams, crediting a colleague, Kristen Nowak, with developing a method for quantifying the flow needed for hydraulic carving designs. That helped him design the system that is being used at the Balm Boyette Scrub Preserve. Engineers are recirculating surface water and pumping 2,000 gallons per minute from a pipe to recreate a 1.500-foot long stream that ran through the property before the 1960s, when the area was mined for phosphate. It's a project of the Southwest Florida Water Management District's Surface Water Improvement and Management program.

Hydraulic carving creates the stream in a meandering way, as Mother Nature would make it, but it happens in weeks as opposed to decades, said Kiefer, 55, who has brought back two other streams using this method. This is the first time it has been used in the southwest water management district, which covers 16 counties, said Janie Hagberg, 53, the environmental engineer in charge of the project. It's being done on land that Hillsborough County purchased through the Jan K. Platt Environmental Lands Acquisition and Protection Program through a $2.2 million grant from the Florida Department of Environmental Protection.

Building the creek is just one facet of the effort to restore the land, said Hagberg, who has worked for 20 years with the water management district's surface water improvement program, returning altered land to the way nature made it, enhancing water quality and creating wildlife habitats. Bul Hed Corporation, the contractor on the project, used earth moving machines to create the stream valley and eliminate the old phosphate pits. Those machines will be used to move the dirt that is blocking the stream's progress to Fishhawk creek. When finished, water will flow over the land and into the stream, then through Fishhawk Creek and on to the Alafia River.

This summer, environmentalists will plant native vegetation in the stream and wetlands to help filter the water, Hagberg said, using such plants as pickerel weed, fire flag, bulrush, spike rush and cypress trees, which will provide habitat and stabilize the banks.

The engineers are "letting the channel decide where it wants to go,'' as Hagberg puts it. The meandering is determined by the sediment and other materials being carried in the stream and the resistance of soil, rock layers and vegetation, Kiefer said.

Though recreating streams is the most practical use of hydro carving, Kiefer said, it could be done on a larger scale if the builders had a large enough site and the ability to recirculate the water.

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"You could do the Amazon river this way,'' he said, "if you could capture the flow.''

Contact Philip Morgan at pmorgan@tampabay.com or (813) 226-3435.