Case Studies - Fall 2018

Case Studies - Fall 2018

Chimney seals effectively stop manhole I&I

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Crawler camera helps stormwater utility increase productivity

Problem: The Roanoke River, which meanders through residential and industrial neighborhoods in Roanoke, Virginia, serves as one of the main water sources for the city. To protect the water quality for years to come, the city formed the Roanoke Stormwater Utility. To achieve their goals, the utility needed a reliable, efficient inspection system.

Solution: Envirosight’s ROVVER X inspection platform provided the efficiency the utility needed to assess its system for defects — and find any infiltration and exfiltration that came with that damage. The compact system can be transported in built-out inspection trucks or vans, on the back of a pickup truck, or out of an all-terrain vehicle. The crawler is also agile and maneuverable, with a short wheelbase and zero-degree turning radius that makes it easy to overcome any obstacle. The system has the power to tackle long runs. With 1,000 feet of lightweight, buoyant cable, it can crawl upstream or down, tackling offsets and inclines with ease.

Result: The utility improved from inspecting 17,000 feet of pipe in one year to inspecting more than 100,000 feet of pipe in five months. This increase in inspection capacity dramatically improved its ability to identify line defects. Additionally, the team discovered nearly 200 miles of storm line that had been forgotten and neglected. The city now understands its collections system and can identify sources of stormwater pollution and infiltration and continue working toward its water-quality goals. 


Mechanical point repair sleeve used in sewer preventive maintenance program 

Problem: The preventive maintenance program for the Franklin Township Sewerage Authority in New Jersey prioritized identifying and addressing defects to reduce I&I. But the repair process had become a bottleneck: Staff engineers spent too much time planning how to tackle each defect, and the contractor bidding process was slow. In the meantime, groundwater infiltration would continue to fill the pipe. The authority needed an option that was easier and more efficient.

Solution: Quick-Lock point repair sleeves from Pipeline Renewal Technologies provide infiltration abatement and structural repair, and they can be installed by just two people in under 30 minutes. Made of a heavy-gauge 316L stainless steel cuff and an EPDM rubber gasket, a sleeve can restore strength and stop infiltration immediately. Users position and prepare the sleeve with a standard inspection crawler, and the device is then expanded pneumatically to seal out infiltration. With no contaminating resins or prolonged cure time, this mechanical solution requires neither wet-outs nor bypass pumping. And, it can be installed directly over “gushers” to eliminate high-volume sources of I&I.

Result: With the addition of Quick-Lock to their repair options, the authority is now able to identify a defect, determine if it is a candidate for Quick-Lock, and make the repair immediately. After just two months of utilizing Quick-Lock on an as-needed basis, the authority had installed seven sleeves and was saving over $6,500 per month, in addition to the savings from reduced I&I. 


Lining products provide a solution for leaking manholes

Problem: A New York sewage authority determined a substantial amount of groundwater was entering their collections system through their manholes, placing stresses on the system and additional cost to treat I&I.

Solution: A contractor from New Hartford, New York, was brought in to find a solution. Working with the Sauereisen representative, a rehabilitation system was recommended to restore the manholes, prevent further degradation, and stop the infiltration. The manholes were cleaned to remove old coatings and loose mortar, then active leaks were sealed with InstaPlug No. F-88 (hydraulic cement). Next the manholes received a 1/4-inch cementitious lining of RestoKrete F-121 Substrate Resurfacer before applying a topcoat of SewerGard at 125 mils for corrosion resistance from chemicals common in wastewater environments. The chimney sections were coated with elastomeric F-88 ChimneySeal, a flexible, fiber-reinforced urethane material that bonds well to substrates typically encountered in manholes. Surface preparation and application is done by hand with the F-88 and applied in a single layer at 1/4 inch.

Result: I&I was practically eliminated. 


Liner used to rehabilitate manhole deterioration from hydrogen sulfide

Problem: A 4-by-6-foot precast concrete manhole in Key Largo, Florida, was in need of relining due to deterioration of the existing coating and concrete from hydrogen sulfide exposure. The manhole was located on a city street where traffic needed to be redirected, so quick turnaround time was important.   

Solution: Maxx Environmental was contracted for the job. The surface preparation included hydroblasting to remove the loose coating and concrete. The contractor then mixed CLADLINER according to the manufacturer’s instructions, and the product was poured into a cement hopper and sprayed into the manhole. It was then back-troweled to produce a smooth finish.

Result: The manhole rehab was completed in less than three hours from start to finish. The manhole was not only rehabilitated, but also is now protected from hydrogen sulfide. 


Grout system stops high-volume manhole leak

Problem: During a routine sewer line inspection on Tupper Street in the town of Milton, Ontario, cameras found a manhole leaking a substantial amount of groundwater into the sanitary system. After identifying the leak, Peter Knight-Chevalier, president of Rain Drain Restoration, was called to evaluate the manhole and propose a solution for the infiltration issues.

Solution: PARSON SEAL-TITE, part of the manhole rehabilitation product line from Parson Environmental Products, was chosen because of its ability to stop leaks up to 50 gpm. The moisture-insensitive, two-component, fast-reacting hydrophobic polyurethane grout is designed to stop high-volume active leaks in manholes, pump stations, and other wastewater structures. It is packaged in a dual cartridge with a static mixer and is injected at or near the source of the leak, using a manual dual-component caulk gun. The product cures to a dense, rigid mass in approximately 30 seconds and contains no solvents, CFCs, or HFCs.

Result: The grout was able to stop the high-volume leak in less than 4 minutes, resulting in a significant reduction of groundwater in the town’s sanitary sewer system. 


Manhole barrier prevents manholes from leaking

Problem: Several years ago, the city of Rochester, Minnesota, began an extensive rehab program. Each spring they would concentrate on different areas of their community to rehab manholes. During heavy rains, the city’s treatment plants were pushed to capacity levels, making the need to reduce the extra water entering through leaking manholes even greater. Also, as the manholes deteriorated, the need to rehabilitate them became even more important.

Solution: The city chose to install the I & I Barrier from Strike Products. Sealant provided with each barrier is placed on top of the cone section and followed by installation of the barrier. Either concrete or plastic grade rings are then put in place, with the first ring placed on the flange of the barrier dry. This allows water to leak out into the ground table. There is also a lip on the barrier, which keeps the barrier in place and water out. The remaining rings are then stacked and either concreted or glued in place to the proper height where the casting will sit. Contractors like the quick installation and are able to cut the barrier to fit inside the casting.  

Result: With the installation of the I & I Barrier, there is less water entering the sanitary system, which saves the city money and also extends the life of the treatment facility. 


Manhole encapsulation system helps eliminate combined sewer overflows

Problem: In the rural area of Honesdale Borough, Pennsylvania, locals like to spend their time enjoying activities such as fishing, rafting and biking. As bicyclists pedaled around town, it became harder for them to overlook the increasing cracking of the pavement above their manhole structures. The challenge was several combined sewer overflows. The structures were receiving excessive inflow and infiltration, resulting in hydraulic overload conditions that needed to be addressed. 

Solution: The Central Wayne Regional Authority enlisted the assistance of Entech Engineering, which recommended the use of WrapidSeal Manhole Encapsulation System from CCI Pipeline Systems. “Entech has been using WrapidSeal on projects for over 12 years simply because it works,” says Bryon Killian, P.E., LO. “Starting in this industry 16 years ago, I personally conducted thousands of manhole inspections and found the manhole riser rings and joint sections were almost always the primary cause of infiltration. In addition to helping prevent I&I, we also use WrapidSeal to ensure pavement life by preventing fines being washed away with infiltration, causing pavement cracking around manhole structures.”

Result: Once these structures were repaired and protected with WrapidSeal, the amount of I&I causing the hydraulic overload conditions during wet weather was significantly reduced, accounting for the elimination of 13 CSOs over the last decade. 


Chimney seals effectively stop manhole I&I

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. According to Conrad, 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: What Tru Test found was that the top retaining band of the 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 manholes would already be leaking two weeks after construction. Instead, an immediate impact on I&I was achieved. 


Manhole resurfacing utilized in sensitive environmental area

Problem: The Moraine Park Campground, the only year-round campground in the Rocky Mountain National Park, was experiencing severe infiltration issues in its sanitary system, especially during the spring snowmelt. The system consists of 2,346 lineal feet of 6-inch gravity pipe and 11 manholes in an environmentally sensitive area 8,160 feet above sea level. Park officials knew the system needed to be repaired but were worried that the rehab process could lead to significant park closures. 

Solution: The National Park Service tabbed Advanced Solutions Group for the job. Given the time-sensitivity around the project and the extreme conditions the system has to withstand, Advanced Solutions Group employed Fold In Place PVC for the sewer lines and SpectraShield Liner Systems for the manhole rehab. SpectraShield Liner Systems’ trenchless rehab proved ideal since it can be used to resurface a typical manhole in less than an hour. 

Result: Due to the fast and easy application, the campground’s manhole rehab was completed in two days and is guaranteed infiltration-free for 10 years. 


Geopolymer lining a fit for manholes in dry conditions

Problem: The town of Cheektowaga, New York, began rehabilitating its manholes by trying out an assortment of products in extremely dry conditions. The township found that ordinary Portland cement liners and calcium aluminate cement liners were prematurely cracking only hours after installing the lining.

Solution: Milliken Infrastructure Solutions reached out to the township’s design engineer and suggested using GeoSpray geopolymer, which is less sensitive to cracking in dry manhole conditions. Compared to Portland cement linings, GeoSpray geopolymer has about double the compressive strength (8,000 psi) and about triple the flexural strength (1,500 psi). This added strength, coupled with its resistance to sulfuric acid corrosion often found in sanitary sewer systems, gives the geopolymer mortar a 70- to 100-year life cycle. “GeoSpray geopolymer mortar has a noticeable product consistency and quality that my crew and I appreciated during the project,” says Dennis Sullivan, vice president and general manager of the installation contractor, National Water Main Cleaning.

Result: GeoSpray mortar went on quickly and easily and did not crack. The township was pleased with the pilot application and specified GeoSpray mortar on a 5,000 vertical linear foot manhole 2018 project. “This product’s user-friendly application characteristics lead to efficiency in the field,” Sullivan says. “These characteristics make it a preferred product on certain future projects.” 


Riser system keeps manhole castings and lids in place

Problem: Twenty-nine manhole riser installations were placed in the roadways of Cumming, Georgia. Due to the installations degrading quickly during normal, everyday traffic, the manhole casting/lids were moving and getting displaced, which not only compromised ride quality, but also resulted in inflow and debris falling into the sewer collections system.

Solution: James Waite Inc. was called in to assess the situation, and the decision was made to remove the grade rings from the 29 manholes and replace them using the Whirlygig Manhole Riser System. Once in place, the riser/collar forms were trimmed to finished height, during which the slope of the roadway is automatically reconciled. After pouring the concrete collar, the result is a monolithic structure impervious to corrosive elements.

Result: Traffic flow across a planar surface was safely restored in short order, and a smooth ride was ensured over the lifetime of the installation. 


Pipeline rehabilitated in residential driveway results in cost-savings and time-savings 

Problem: A 6-inch vitrified clay pipeline in Carrollton, Texas, had significant damage, causing heavy I&I. The pipeline was buried 10 feet deep in an alleyway and through a resident’s driveway. Open-cut replacement would cost between $10,000 and $12,000, require at least three days of labor, and the alley would need to be closed during the repair. In addition to the expense to the city, it would be an inconvenience to the homeowner and neighborhood. 

Solution: Hoping to avoid an expensive and time-consuming excavation, the city turned to Source One Environmental to provide a trenchless pipe rehabilitation solution. Rehabilitating the pipeline with a CIPP method would restore the pipeline’s structural integrity and improve the overall performance, at a fraction of the cost and time. The company installed the PipePatch point repair system 10 feet deep to cure the broken 6-inch pipeline. 

Result: PipePatch eliminated the need for digging by creating a pipe within a pipe with minimal change to the original diameter, improving the overall flow capacity. The repair was significantly less expensive than the original estimate and took less than three hours to complete. Not only was the residential area virtually undisturbed, the rehabilitation added decades of additional service life to the pipeline, ensuring that the residents would not encounter this again. 



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