Welcome to Fort Lauderdale and the Las Olas Isles. The Everglades are to the west, called “the sea of grass.” Beautiful beaches are to the east. Water is everywhere. You can travel around the city by water taxi on the Intracoastal Waterway and the surrounding canal system. The Las Olas Isles are located just east of downtown Fort Lauderdale.
The city has an ongoing program that entails the modernization and rehabilitation of its water and wastewater infrastructure. The City has renewed many miles of mainline pipe with cured-in-place pipe (CIPP) lining and recognizes the need to seal the laterals and their connection to the mainline pipe. The groundwater above the pipe produces hydrostatic pressure, which causes severe infiltration.
The City currently has an ongoing contract with LMK Pipe Renewal LLC, a local state-licensed general contractor specializing in trenchless pipeline repair. The project consists of inspecting all the service laterals, lining the connections and the defective laterals. The project area has 13 pump stations with approximately 600 service connections. The goal is to restore structural properties to the pipe by installing a cured-in-place (CIP) lateral and lateral connection liner forming a verifiable non-leaking main/lateral connection.
Lateral inspections are performed with an IBAK inspection unit, utilizing a color pan-and-tilt lateral camera. Lateral inspections done with a pan-and-tilt color camera produce a superior pipe inspection vs. the traditional straight-line lateral camera systems. During the condition assessment, LMK Pipe Renewal utilized the inspection camera’s sonde, allowing the technicians to locate existing cleanouts that saved the City unnecessary costs for installing a new cleanout.
“We would be at a great disadvantage if we did not have this tool to perform the lateral inspections on the Fort Lauderdale project,” says Mark Gulyas, project manager, LMK Pipe Renewal.
Many area residents don’t have driving options, as their homes are built on narrow streets that end in a cul-de-sac. Any excavation is going to negatively impact traffic flow and the deeper repairs may necessitate a road closure. Wherever possible, trenchless repairs are performed in the City for both mainline repairs and laterals. Trenchless repairs have significantly reduced the negative social impact and simultaneously have helped save the City money vs. conventional dig and replace methods.
“The most difficult utility projects I have been involved with in my 26 years with the City of Fort Lauderdale have been new sewer construction and excavation for sewer repairs. Groundwater conditions, sand and/or muck and working in the middle of the road result in high-impact, difficult working conditions,” said City engineer and program manager Paul Bohlander, P.E. “Relining results in a renewed pipe without the adverse impacts of excavation on the road, other utilities, traffic and adjoining property owners. And sewer repair is essential to the City of Fort Lauderdale, where most of our gravity sewers and laterals are in groundwater and where inflow and infiltration contributions to the wastewater flows are significant — and would otherwise result in the need to expand the WWTP at great expense.”
In cases where there is not an existing cleanout, LMK Pipe Renewal is utilizing the Vac-A-Tee System by LMK Technologies. Vac-A-Tee is a PVC saddle that is snapped onto the pipe and adhered by sealing to the exterior of a lateral pipe. The method of installation first requires accurate locating that is performed during the initial condition assessment. Then, the lateral pipe is exposed by hydro-excavating a 16- to 20-in. diameter borehole. The system is so clean that in some cases the homeowner is not even aware that this work is being performed. Where existing cleanouts are located and identified to be deteriorated or broken, traditional open-cut excavation is utilized to replace the defective cleanout.
The lateral conditions observed during the video survey dictate which method of cleanout installation is utilized. Overall, the Vac-A-Tee is the quickest, safest and cleanest method. The project’s obstacles such as tight roads, high water table and aboveground conflicts, which limit the excavation areas, all make for a challenging project but are overcome when using the right technologies.
The project area recently had all the mains renewed using CIPP. When the mainline liner is installed, the coating on the outside of the pipe (used to contain the resin and improve flow rate) ended up as the surface of the interior of the newly installed CIPP main. When choosing a lateral rehabilitation method, the most important part of the project is the connection at the main. The surface material present inside the mainline liner is also an issue to consider. If the interior of the newly relined mainline is coated with one of the popular coatings like polypropylene or polyethylene and the lines are in service that introduces fats, oils and grease (FOGs), then the challenge to seal the lateral to the main by simply adhering resin becomes unpredictable for a minimum 50-year service life design. This challenge is also overcome by using the right technologies.
“The project is progressing very well. It looks like the City will benefit from the [T-Liner] technology for years to come. This area has needed this type of repair. Lining the mains just didn’t stop all the infiltration for us,” said Jean Examond, project engineer for the City of Fort Lauderdale.
On this specific contract, the City of Fort Lauderdale specified the ASTM F2561-06 standard for a structural one-piece main and lateral lining assembly that incorporates compression gaskets. The one-piece lining structurally renews the main pipe fitting and in most cases extends up the lateral to the property line. In some cases where a cleanout is not practical, LMK’s T-Liner Shorty system is being utilized to structurally seal the connection and extend three-feet up the lateral. Stamped engineering design calculations in accordance with ASTM F1216-09 were provided.
Rohan Engineering provided the engineering work for both the lateral tube and the full-circle interface seal (connection at the main) to determine the minimum liner thicknesses. The CIPP design criteria for the lateral pipe is “fully deteriorated.” The connection CIPP design criteria for a previously lined mains is “partially deteriorated,” because the hydrostatic load is the primary issue to address. For mains that are unlined (no mainline liner installed), the design mandates a “fully deteriorated” pipe condition be utilized. The CIPP design for the main connection is typically overlooked; however, it is a key component to the success of a structurally sealed connection designed for a minimum service life of 50 years.
“The T-Liner repairs are progressing well; the hydrophilic bands act like gaskets and the full circle main connections seal off the water. So far the post videos have all looked pretty impressive. Overall, I think the project is looking good. I like the system,” said Scott Sawyer, City of Fort Lauderdale, engineering inspector II.
In Florida, water is everywhere with much of the state’s high water table causing high levels of infiltration and the demand for lateral lining has been progressively growing. It is becoming widely recognized that rehabilitating the manholes and mainline sewers alone will not solve the I/I issues that are present in any collection system. Without addressing the lateral connections and lateral piping issues, only part of the system’s problems is corrected. Designers should not neglect the lateral connection in all the material thickness calculations; the connection is the deepest, most important part of the lateral rehabilitation.
Kristina Kiest is marketing manager at LMK Enterprises, which is headquartered in Ottawa, Ill.