Case Studies - Winter 2020

Sprayable mortar used to rehabilitate media basins

Problem: 

The city of Houston Water and Wastewater Utility faced the monumental task of rehabilitating more than 220,000 square feet of hydraulic-abrasion-damaged cast-in-place concrete filter media basins in its filter media and pilot plant rehabilitation for its East Water Purification Plant project. The project required that all of the surface defects in the existing concrete walls, troughs, gullets and discharges be repaired to their original uniform thickness and surface finishes. In addition, the project required the replacement of all expansion joints and the use of chemical grout to stop water infiltration seepage.

Solution: 

The general contractor recommended dry, packaged Reliner MSP geopolymer mortar from Standard Cement Materials for repairing each deteriorated concrete structure. This brought the basins to their initial capacity and adapted the components for new service beyond their original design, reducing their life-cycle cost. 

Result: The wet-gunned, sprayable mortar provided a fast, safe and simple procedure for the repair, which corrected the deficient basins, minimizing the potential for deterioration in the future. The project time was approximately 12 months, and the repair method did not adversely affect the other trades or prevent the contractor’s ability to achieve substantial completion on time. 888-278-1337; www.standardcement.com


Chemical grout enables municipality to seal manholes

Problem: 

A costal municipality near Long Branch, New Jersey, was facing inflow and infiltration issues that were the result of defects in piping and manholes, allowing groundwater, sand and other debris to enter the system and flow to the treatment facility, causing overflow problems. This municipality was tasked to locate, repair and reduce I&I to minimize the burden and financial replacement costs of aging collections and treatment systems. In addition, freeze-thaw cycles, heavy traffic and ground erosion caused stress on concrete and open joints, creating a path for water infiltration.

Solution: 

The municipality decided on a more permanent solution using chemical grouts from Sauereisen. The polyurethane chemical grouts are water activated and will repel water and push it away. When fully cured, they typically form a rigid system. Hydrophobic grouts have great expansion properties, typically 20 times their original volume; a low viscosity that enable them to flow easily; and a quick set time for filling voids and stopping active leaks. All this saves downtime and allows structural rehabilitation to proceed.

Result: Knowing the causes and solutions to the problem has helped the municipality’s engineers and contractors repair and reduce I&I and reduce its economic and environmental impact. 412-963-0303; www.sauereisen.com


Manhole risers make the grade after repaving project

Problem: 

South Walton Utility Co. is a member-owned, nonprofit corporation serving a small community near Miramar Beach, Florida. It is responsible for raising its own storm and sewer manholes to grade after repaving projects. If they set low, water collects around the manhole lid, causing excessive infiltration.

Solution: 

Since 2006, the utility has used Pivoted Turnbuckle Manhole Risers made by American Highway Products to accomplish this chore quickly and effectively. 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. The riser is a flexible, galvanized steel ring with adjustability provided by a patented connecting turnbuckle. They’re sized in 1/4-inch increments for thickness, starting at 3/4 inch, so that new paving final grades can be matched precisely.

Result: “They’re so much easier to set, compared to jackhammering and raising rims with bricks,” says Richard Schwartz, project manager. “It takes less than 20 minutes to raise manholes this way, compared to six or seven hours with excavation.” 888-272-2397; www.ahp1.com


Manhole and catch basin rehab accomplished without business disruption

Problem: 

Bay City, Michigan, was experiencing multiple failing sanitary sewer manholes and stormwater catch basins in a heavy-traffic area of its downtown business district. Cave-ins and heavy infiltration were present in most of the structures, and remediation of numerous issues needed to be completed in a short window of time with the least amount of disruption to the business community as possible.

Solution: 

Terry Killburn, sewer maintenance manager for Bay City, received a recommendation from Granite Inliner to contact Advanced Rehabilitation Technology (ART) about using OBIC Armor — a multilayer, fast-set, spray-applied polyurea trenchless rehabilitation solution from OBIC — to resolve the issues. Upon deployment, ART crews first removed debris and pressure-washed all the structures to be rehabilitated. Most required the use of dryers to remove all moisture from the substrate, and crews applied grout in the manholes or catch basins that were missing mortar or experiencing major leaks and infiltration. Once properly prepared, the installation team applied OBIC Armor at a thickness of 500 mils. Each structure required approximately three to five hours to complete, and OBIC’s product application process allowed for zero downtime. All of the assets for the project were renewed successfully within two months.

Result: Bay City’s aging downtown underground sanitary and stormwater conveyance system structures have been given an extended life span in excess of 25 years with minimal disruption to the community and lower costs than replacement. “The installers were top notch and had excellent communication skills,” Killburn says. “Best of all, we didn’t receive any complaints from our business community during the project.” 866-636-4854; www.obicproducts.com


Case Study: Lining solution specified for large tank

Problem: 

A 13,000-square-foot tank with a 500,000-gallon capacity located in a privately owned southern Florida country club showed signs of severe deterioration, including exposed rebar as a result of hydrogen sulfide damage. The existing coating required removal, and a structural solution to reinforce the concrete was essential. 

Solution: 

Epoxytec’s CPP Sprayliner was chosen as the solution. It was spray-applied as a topcoat. This two-component, moisture-insensitive, reinforced epoxy is a highly adhesive product that provides chemical resistance and is 100% solids. It can be sprayed with ultrahigh build, between 1/16 and 1/4 inches per pass conveniently from a plural-component heated spray rig.

Result:  This project was completed on time, and all parties involved were satisfied with the results. The protection will enhance the life of this infrastructure and has brought it back to like-new condition. It allowed for an efficient installation time while also providing quality, durability and strength for years to come. 877-463-7699; www.epoxytec.com


Monitoring system provides flooding data

Problem: 

The city of Green Bay, Wisconsin, sought a solution to get real-time visibility of several manhole locations as it grappled with the need for an estimated $150 million in sewer/stormwater infrastructure repairs and upgrades. The city especially wanted a better picture of when and where water infiltrates the system during rain events, but it also became clear that it needed more information about dynamic level changes due to infiltration from rivers. 

Solution: 

Green Bay deployed SmartCover Systems to monitor the East River and Fox River and gain visibility about how upstream flow and river level changes impact downstream flooding in the sewer and stormwater collections systems. The East River monitoring uses a configuration in which the unit is hung below the Mason Street bridge to monitor the water level below. During rainfall events, the unit identifies river level changes. At one point, the East River rose to just 7 inches below the bridge.

Result: By monitoring the rapid rise and fall of local rivers, Green Bay was able to correlate river level changes with stormwater infiltration into the collections system. The ability to aggregate and analyze data from the SmartCover system is helping the city more clearly understand the dynamic relationship between upstream flows and downstream infiltration impacts, prepare for water surges, improve resource allocation and prevent spills. 760-291-1980; www.smartcoversystems.com


Manhole repair completed using grade adjustment system

Problem: 

In early 2010, a manhole had been identified as needing repair by the Narragansett Bay Commission in Providence, Rhode Island. The issue was inflow through a deteriorated brick-and-mortar chimney that had caused pavement failure around the manhole frame. The manhole was directly in the wheel path of all vehicles, and due to the volume of traffic in both directions, a quick and easy, but long-term repair was needed.

Solution: 

PRO-RING, a lightweight manhole grade adjustment system made from expanded polypropylene from Cretex Specialty Products was selected for this repair. Its high-strength, lightweight plastic makes it a suitable material to replace traditional construction methods using masonry materials. This system is fast, safe and cost effective, with one worker being able to complete an entire adjustment in just minutes. On the day of the repair, crews and traffic control arrived and were set up by 7:30 a.m. The pavement was saw-cut, and the manhole was excavated and ready for reconstruction by about 8:50 a.m. The installation of the PRO-RING started at approximately 9 a.m., with some repair of the brick manhole using a high early strength repair mortar and then installing the adjustment rings and manhole frame casting. The installation was completed by 9:20 a.m., and the excavation was backfilled, compacted and prepared for the asphalt patch.

Result: Since the installation over nine years ago, this site has been subjected to an estimated 200 million traffic impacts, and annual inspections show no leakage or negative effect on the PRO-RING system and surrounding pavement repair. 800-345-3764; www.cretexseals.com 



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