Risers keep manholes at grade in heavy hurricane area

Problem: Fairhope is a small city of just 15,000 residents situated on the cliffs and shoreline of Mobile Bay in Alabama’s Gulf Coast. Infrastructure maintenance can be a challenge here for all the usual reasons and one unusual one: The city has a history of devastation and flooding by hurricane, including Hurricane Frederic in 1979 and Hurricane Katrina in 2005. But the city doesn’t have a problem keeping manholes at grade after roadway resurfacing projects, not in recent years anyway.

Solution: For 15 years, Fairhope has been specifying the American Highway Products Pivoted Turnbuckle Manhole Riser. The risers are sturdy, flexible rings made of galvanized steel, and they can be ordered in precise diameters to match any manhole and in precise thicknesses (with increments as fine as a quarter inch) to precisely match paving lifts. The “pivoting turnbuckle” is an adjustable linkage that allows the risers to be set loosely in an original utility rim, then expanded with a Phillips screwdriver (used as a lever) to seat tightly and securely.

Result: At-grade risers are better for roads in many ways, compared to concrete ring replacement. They don’t set low, so water doesn’t collect around the manhole lid causing excessive infiltration; and they don’t set high, so vehicle tires don’t jar the lid and rim continually. And since risers are usually set just before paving runs, the newly raised manhole is surrounded by new, contiguous pavement, and that prevents water and freeze-thaw damage in the pavement around the manhole. 888-272-2397; www.ahp1.com.

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City chooses centrifugally cast option to rehab manholes

Problem: The city of Hampton, Virginia, has a collections system that dates back to the early 1940s, and nearly 75% of the system is below the groundwater table. During a rain event of 1 inch or more, ground-water and rain-derived inflow and infiltration greatly overtaxes the system’s capacity. In addition, I&I contributes to the wear and erosion of pipes and manholes and increases pumping and treatment costs.

Solution: After careful consideration, Hampton selected the Permacast self-install solution from AP/M Permaform. The system centrifugally compacts high-strength, fine-aggregate concrete on the prepared interior of a deteriorated manhole. The crew also reestablishes the bench and inverts and installs a plastic manhole insert to stop the inflow. The bidirectional spincaster is raised and lowered with a winch to achieve thorough coverage and complete compaction without having to trowel.

Result: Using the flow data and similar rain events to analyze the results, the efforts reduced inflow by 18% in their initial pilot program. The city subsequently implemented a full I&I reduction program, with a goal to rehabilitate 100% of the city’s 11,000 manholes. A three-person crew now structurally lines about 400 manholes each season between April and October. The crew averages between three and four manhole rehabs each day, depending on depth, condition and access. 800-662-6465; www.permaform.net.

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Lining system used to rehab manholes damaged by roots

Problem: Deterioration caused by high water infiltration and severe root intrusion led to the need for rehabilitation of several wastewater manholes located in the town of Avon, Connecticut. Savy & Sons were contracted to restore the 4-by-11-foot redbrick chimney seals of these concrete manholes.

Solution: Active water leaks were addressed by injecting a polyurethane hydro-active grout and coating with CLADSTOP 1 from CLADLINER. Due to the low surface temperature of 20 degrees F, Savy & Sons heated the surface to 80 degrees F using an alternative heat supply. CLADSTOP 1 is designed for structural patching and for use as a leak stopper and water plug. 

CLADSEAL was applied using a hand trowel to seal and protect the substrate. CLADSEAL is an elastomeric manhole chimney sealer and has maximum elongation and tensile strength, as an advanced urethane-acrylate 100% solids, epoxy hybrid. Once cured, the material is categorized as a hybrid flexible elastomer exhibiting high tensile elongation. It has the properties of traditional urethanes without the isocyanates and boasts a long shelf life. 

Result: From the start of this series of repairs in December 2018 continuing through January 2019, Savy & Sons addressed each manhole individually. “This awesome product was just right for the job,” says Travis Savy, company owner. “CLADLINER’s customer service is outstanding, and the products are amazing and of great quality. There is no comparison.” 877-708-2523; www.cladliner.com.

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Root control foam solves sanitary sewer overflows

Problem: The West Bay Sanitary District in California had an excessive number of sanitary sewer overflows prior to 2010. They determined that 90% were root-related.

Solution: Duke’s Root Control was brought in initially to apply its Razorooter II foam to a neighborhood that was notorious for root stoppages, averaging 14 overflows a year. The whole system includes 210 linear miles, all of which has been fully inspected via CCTV. The database is queried to locate root problems, and those pipes with issues are added to the program. Duke’s Root Control crews are contracted to apply the foam application, which allows West Bay’s crews to continue assessing pipes, perform in-house spot repairs and clean hot spots.

Result: The following year, there were zero overflows in the neighborhood, and zero for several years after that. West Bay is now foaming 195,000 feet a year. “Duke’s Root Control program has been an integral part in reducing our SSOs,” says Serio Ramirez, West Bay Sanitary District operations superintendent. “It is one of the primary reasons we have gone from having 49 SSOs in 2009 to only four in 2018, where two out of the four were contractor discharges of water and mud.” 800-447-6687; www.dukes.com.

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Access assemblies help a town prevent I&I issues and improve safety

Problem: The town of Cary, North Carolina, has dozens of streams and lakes located in its boundaries, and it is prone to occasional flooding. During major rain events, stormwater occasionally gets into the sanitary system, causing sewage backups that can overflow from manholes into nearby lakes. When sewage infiltrates creeks and lakes, fish and wildlife are endangered and the town must deal with the resulting cleanup and potential fines. They needed to find a better solution. After trying elevated manhole covers, they discovered that the covers would pop off when stressed.

Solution: EJ provided the REVOLUTION Access Assembly, an elevated manhole cover that required no lifting. Once the bolts are removed, workers can easily rotate the lightweight cover away from the opening to access the manhole. It stays attached to the frame via a cast-in stainless steel rod. One worker can easily access the elevated manholes. It also seals tightly when closed, preventing I&I.

Result:“When the lid is seated correctly, the REVOLUTION works great for preventing any type of inflow, pretty much across the board, everywhere we’ve installed it,” says Robert Hirt, P.E., utility engineering supervisor for the town of Cary. A backup along the Walnut Creek sewer outfall, following Hurricane Matthew in 2016, proved that point without a doubt. 800-626-4653; www.ejco.com.

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Liner system helps Florida coastal city with I&I issues

Problem: Fernandina Beach, Florida, is situated on the shores of the Atlantic Ocean to the east and the Intracoastal Waterway to the west and receives an average annual rainfall of 51 inches. Consequently, the groundwater table is extremely high. Its principal sewer treatment plant is permitted for 2.5 mgd. The sanitary sewer system is older, with approximately 95 miles of gravity sewer, force mains and 1,461 manholes. The system’s infiltration problem became so acute that plans were being evaluated for a treatment plant expansion expected to cost in excess of $20 million. 

Solution: Beginning in 2005, John Mandrick, Fernandina Beach utilities director, began a phased I&I reduction program using the SpectraShield Liner Systems for manhole rehabilitation and CIPP. It is a multilayered lining system designed to stop infiltration and prevent corrosion.  

Result: By 2014, flows had been reduced by 800,000 to 1 mgd. A major plant expansion was avoided, operating costs were reduced, energy savings were realized and groundwater was conserved. The Environmental Protection Agency estimated the reduction in flow reduced operating costs by more than $450,000 per year. The energy savings from the reduced flow volume is in excess of 200,000 kWh per year. Ground-water is now percolating into the local groundwater table and not the treatment plant. 800-284-2030; www.spectrashield.com.

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Chimney seals prevent I&I in new manholes

Problem: During the construction of a new subdivision near Louisville, Kentucky, the specification on new manholes stated that all had to be vacuum tested after construction. Upon passing the vacuum test, an internal mechanical chimney seal had to be installed to prevent future I&I into the sewer system, thus preventing costly treatment of unnecessary water.

Solution: The project was awarded to Tru Test and included the installation of more than 50 internal manhole seals. Dave Conrad of Tru Test had used Trelleborg Pipe Seals’ DrainFlexRib Manhole Chimney Seals for several years. The solution consists of an EPDM seal, which has a rib design that allows vertical and lateral movement, while still ensuring a watertight seal. The waveband technology creates a more effective seal by concentrating the compressive force of the expansion band, effectively capturing the rubber between the band and the concrete. The chimney seals were installed before the contractor had finished the final asphalt road surfacing. After completion of the road grading, Tru Test went back to check the installation. This was less than two weeks after the manholes had passed the initial vacuum test.

Result: The top retaining band of the Trelleborg DrainFlexRib seal was already performing. It held back water that had leaked through the failed mastic and concrete grouting that the manhole contractor had used to help pass the vacuum test. Without the installation of the chimney seals, the newly installed manholes would already be leaking two weeks after construction. Instead, an immediate impact on I&I was achieved. 800-626-2180; www.trelleborg.com/pipe-seals.