Cavache Completing Cleanup of Muck-Clogged Lake Trafford in South Florida
By Judith Powers
Cavache Dredging is midway through removing a thick layer of muck from Lake Trafford in South Florida.
The project is the third and final phase of a decades-long effort to rid the 1600-acre recreational lake of a layer of composted vegetation – eight feet thick in places – that caused a massive fish kill in 1996.
The first project, in 2004, involved dredging the center of the lake and building a confined disposal facility. Phase II, in 2006, was to have cleared the muck from the near shore areas of the lake, but drought conditions stopped the project before it was finished.
The South Florida Water Management District (SFWMD) awarded Phase III last spring to Harry Pepper & Associates, Inc. for $7,461,664. Harry Pepper is managing the dredged material treatement, and subcontracted Cavache to perform the dredging of 2,090,000 cubic yards of material from a 1156-acre portion of the lake.
“We have found our niche in the 16-inch dredge range,” said Anthony Cavo, who, along with Adam Adache, formed and operates Cavache, Inc.
The Lake Trafford project was a natural for them, requiring a dredge that could be transported over land, and the knowledge to surgically dredge only the muck. There is zero tolerance for any sand in the discharge. The aim is to return the lake to its natural sandy bottom.
They are using their dredge Mary Lou, a 16-inch Ellicott 1170 retrofitted with a 95-foot-long spud carriage that gives the dredge a swing of about 350 feet. To ensure that only the muck would be dredged, they removed the cutter and are dredging through the oval suction pipe. A “visor” welded to the top of the pipe concentrates the suction on the bottom, and extensive testing of the finished dredge cells has shown only a miniscule layer of muck remaining.
Discharge is through 18-inch HDPE SDR 17 floating and land discharge line, three miles to the diked placement site.
The dredge is equipped with DredgePack® software, a Hemisphere Crescent VS100 Series GPS compass for heading and positioning, and a Rieker H4 Inclinometer, as well as a Ronan Engineering nuclear density meter. However, the slurry is so dilute that it barely registers, said Cavo.
The muck layer is from eight to 32-inches thick, and the lake varies from five feet to about 12 feet deep.
The project is divided into 750- x 750-foot-square cells, each of which takes about three days to complete. At completion of a cell, representatives from the SFWMD and the prime contractor join a crew that tests the cell in five spots, pushing a Plexiglas tube into the bottom, placing the sample next to a gauge and photographing it.
The maximum allowable muck level is 2 1/2 inches, and the cells have all measured well within that parameter, said Cavo.
The containment area consists of three large cells that feed into a polishing pond. The floating pipe goes ashore at the staging area in the marina on the northeast corner of the lake, and a booster pump moves it the rest of the way to the settling ponds. The background turbidity level in the lake is 14 NTU. After passing through the settling ponds and polishing pond, the water is pumped back into the lake at 1.5 NTU, which is close to drinking water quality.
The dredging portion of the project is scheduled for completion in October, (weather permitting) and the entire project by February 2011. The local people are already anticipating the renewal of their fishing and boating lake. On April 22, the Florida Fish and Wildlife Conservation Commission restocked the lake with 150,000 largemouth bass hatchlings. Boating has continued on the lake throughout the project, and the plan calls for sinking and marking a 100-foot section of the floating pipeline as a passage for boaters.
But the project is not just for recreation and fishing. Lake Trafford is part of an area-wide water system, and last September 22, the SFWMD allocated $3 million to complete the Lake Trafford dredging, out of their 2010 $1.5 billion budget for “the agency’s flood control and water supply missions as well as its continued progress to restore the South Florida ecosystem, which includes America’s Everglades,” according to the minutes of the meeting.
Anthony Cavo and Adam Adache formed Cavache Dredging 10 years ago in Fort Lauderdale. Lifelong friends, they had been around dredging all their lives through Cavo’s family, a multi-generation dredging family.
“We have been best friends since we met in kindergarten over 34 years ago,” said Cavo. “We went to the same schools, were college roommates, best man in each others weddings and godparents to each others kids.”
The friends worked jobs in the Cavo family’s three-generation dredging business during summers and school breaks, which gave them a good working knowledge of dredging.
“We were entrepreneurs at a young age – we used to buy, fix up and sell equipment,” said Cavo. The two built their first dredge in the late 1990’s and put it to work.
Adache’s strong background in business and finance, and experience in his own family’s architectural and general contracting business, adds the know-how for making practical dredging knowledge into a successful business venture.
“We want to grow, but only to a certain size,” said Cavo, adding that staying with a maximum dredge size of 16 to 18 inches will give them production capacity while enabling them to take jobs requiring overland transport of their equipment – a niche that doesn’t have many in it at this time.
They do both private and government dredging contracts in lakes, ports, rivers, canals, inlets, and other navigable waterways. They have done projects in the Bahamas and throughout Florida. The company’s mission statement is to conquer projects of all sizes while exceeding client expectations.
Cavo spoke with confidence about the ability of the company to take on any kind of job in their size range, adding that their employees are all highly skilled.
“And we really enjoy what we do,” he said.