Large Diameter Sliplining Restores Function to Florida Levee

The St. Johns River is the longest river in the state of Florida. It is 310 miles long, forming numerous lakes as it meanders from Central Florida north to Jacksonville. The St. Johns River is also one of Florida’s major interior wetlands. The river is separated into three major river basins and several watersheds (such as Lake George and Ocklawaha River), all managed by the St. Johns River Water Management District.

Drought Reveals Condition of Culverts

Located along the St. Johns River on country road 512 in Fellsmere, Fla., the water control structure or levee S-251 was badly deteriorated due to corrosion. If left unrepaired, the structure would become inoperable. A drought exposed the four damaged drainage culverts contained within the levee. Each of these culverts was 72 in. in diameter.

“About two years ago, we were faced with some drought conditions,” said Jimmy Rider, St. Johns Water Management District project manager and field supervisor. “The water had gone down considerably and revealed the culverts, which is when we saw how damaged and corroded they were.”

The St. Johns River Water Management District contracted with Stanley Consultants to perform a diving inspection to determine the extent of the problem. The divers found that all four culverts were badly corroded with numerous holes in the pipes, which threatened the ability to control water in a manner that protected the wetlands and natural resources in the area.

These corroded corrugated metal pipe (CMP) culverts were installed 22 years ago by the Unites States Army Corps of Engineers and did not last as long as expected. The district, as the levee sponsor, was responsible for the current repairs. The district needed an economical solution. Completely replacing the structure would have required a considerable time period during which the structure was not available. This would threaten the wetlands during the dry season when water needs to flow through the structure in order to feed into the wetlands. Relining the pipes eliminated the need for temporary cofferdams and dewatering, thus reducing the environmental impact of the construction.

Big Pipe Chosen to Reline Culverts

“We looked at different repair options,” said Rider. “Sliplining was the best solution.”

ISCO Industries’ large diameter sales manager Bob Kerr, Florida Snap-Tite representative Bruce Larson and Snap-Tite distributor Paul Blastic worked with the district and the district’s chosen contractor, Shenandoah Construction, to provide the best material for lining the culverts.

The material chosen to reline the pipe was 60-in. diameter ProCor profile wall pipe manufactured by Profile Pipe Technologies (PPT) and supplied by ISCO Industries. PPT pipe is made of high-density polyethylene (HDPE). It has a smooth yellow interior for high visibility and meets ASTM International F894 performance requirements.

“We were impressed with the ProCor pipe because of its hydraulics,” said Bill Cote, the district’s supervising professional engineer. “The hydraulics of this pipe are better than anything else we looked at.”

Sliplining the Pipe

The pipe was delivered to the project site in 50-ft lengths. PPT electrofused some of the pipe joints at its manufacturing facility before the pipe arrived onsite. ISCO’s field technician Ron Frazier electrofused the rest of the joints on location. The electrofusion and test equipment were also supplied by ISCO.

“The voltage and time it takes to electrofuse a pipe joint depends on weather conditions,” said Frazier. “Here, I used 32 volts for 19 minutes to ‘cook’ the pipe. There is also a cooling down period. It takes 40 minutes to cool the joints. After that, each joint is field tested to ensure joint integrity.”

The PPT profile wall pipe, once it was fused and tested, was placed into the water with the aid of two of Shenandoah’s divers. The divers then helped guide and submerge the pipe underwater.

Shenandoah Construction handles pipe rehabilitation, mostly trenchless sliplining. The company handles pipe diameters from 12-in. and up. Shenandoah also does prep work, cleans, televises and inspects pipe.
“We provide a full pipe and underground structure evaluation service. We also provide maintenance and trenchless repairs of pipes, culverts and underground structures. Sliplining is a process that returns an old deteriorated pipe into a brand new pipe, without the need to excavate,” said Danny DiMura, vice president and principal of Shenandoah Construction.

The pipe underneath the levee was in poor shape up to about 5 ft from the gate where it had completely worn out. Shaune Rogers, one of Shenandoah’s divers, had earlier excavated and removed the parts that had completely failed. In the sections where there was no old pipe, the new profile wall pipe extended past the culvert close to the gate.

The divers pushed and slipped the new pipe into the old pipe, stopping short of the flood gates. Since the gates were 72 in. in diameter, Shenandoah hired a specialty contractor to design and make aluminum connecting bands that would connect the gates to the 60-in. profile wall pipe. The connecting bands went from a 72-in. diameter to a 60-in. diameter to make the connection.

After the pipes were submerged and slipped into the culverts, the divers came in and attached the aluminum connecting bands to the pipe and the gate.

Then, after the gates were attached to the pipe with the aluminum band, Shenandoah sealed the ends with a non-shrink mortar. Then they added a pump port and a vent port to add cellular grout to fill in any annular space between the old culverts and new liners. Each culvert was relined using a similar technique.

Project Cost Savings

The district was very happy with how quickly the project went and the fact that they saved money by eliminating the need for temporary cofferdams and pumping/de-watering.

“Sliplining with PPT ProCor large diameter pipe represented a $500,000 savings for us,” added Rider. “It would have cost us around $800,000 to dig up and fully replace the pipe. Sliplining cost $300,000 or less.”

Joanna Climer
is a public relations specialist for ISCO Industries.

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