By Tamas Mondovics
In order to fulfill an environmental compensation and restoration agreement, Mosaic announced last month the start of a $5 million mangrove wetland restoration and oyster reef project as well as a borrow pit wetland restoration and tidal creek creation project just south of the Alafia River on the west side of Hwy. 41, off Lula St. in Gibsonton.
According to Mosaic spokesperson, Dave Townsend, the project was necessary and the result of an agreement with the state and county following a surface spill of more than 60-million gallons of acidic waste-water byproduct from the phosphate giant’s Riverview mining plant into Hillsborough Bay during Hurricane Frances, in 2004, when the gypsum stack berm gave way.
Townsend said that with the cooperation of a number of local agencies including the National Oceanic and Atmospheric Administration (NOAA), the two-phase project, while not directly connected to the spill, are both a significant and beneficial improvement for the area.
“The goal of the mangrove project is to restore and enhance mangrove habitat and associated natural resource systems by improving hydrology at the site,” Townsend said. “Pockets of the mangrove forest have exhibited signs of both stress and die-off, principally due to a reduced tidal prism.”
Lewis Environmental Services, Inc., President Roy R. “Robin” Lewis, and Laura L. Flynn, Vice President, hired by Mosaic to oversee the projects, explained that gradual closure of tidal creeks can cause impounded conditions that adversely affect mangroves, thus the restoration will improve the hydrological regime, reverse the decline of the mangrove forest and provide additional nursery and forage habitat for local fish species.
In addition, an oyster reef habitat will be created to provide enhanced shelter and forage habitat for fish and invertebrates.
The project includes the connecting of the Giant’s Camp marina basin to the existing tidal creek with a 50-ft. wide channel spanning approximately 1,000 linear ft. A short bridge will enable road access over the channel.
The construction will also re-open approximately 1,500 linear ft. of additional remnant tidal creeks through mangrove habitat which is largely closed to tidal flows and reconnecting them to the constructed tidal creek.
The project will enhance and create an oyster habitat through the placement of approximately 5,650 sq. ft. of rip rap for oyster recruitment. A portion of the old boat basin will be dredged along with the removal of some exotic plants from approximately two acres along Lula Rd.
Dredging of tidal creeks is expected to be completed by December 2013 and the bridge construction and final stages of construction are expected to be completed in the first quarter of 2014.
The Mosaic Borrow Pit Wetland Restoration and Tidal Creek Creation Project (Borrow Pit Project) is located between Old Hwy. 41 and Hwy. 41 N. Historically, a portion of the parcel was used as a source of fill material for construction of the highway and railroad.
Lewis said that the objective of this project is to improve habitat through creation of an approximately 900 ft. tidal creek and an approximately one-acre pond that will connect to Delaney Creek Pop-Off Canal.
“Removal of invasive vegetation will allow for colonization by native wetland vegetation,” Lewis said.
Construction is expected to begin in October. Estimated completion of this project is June 2014.
Since the 2004 spill and to ensure that such would not happen again, Tino Provenzano, also with Mosaic, said the company has already spent $30 million reinforcing the berms of the gypsum stack, which is able to withstand 80 inches of rain without danger of a breach.
Engineering design was conducted by John Landon, of Landon, Moree and Associates, P.E. Construction will be conducted by Moretrench, Inc. of Riverview, and Tarpon Springs-based Florida Dredge and Dock, Inc. The exotic plant removal will be conducted by Gibsonton-based Milam Environmental, Inc.