Town takes control of stormwater inspections
The Town of Renfrew, Ontario, maintains a storm and sanitary system including 55 miles of pipe. This system requires CCTV camera inspections to ensure the integrity of the infrastructure and to minimize the risk of contamination or flooding. Being a small municipality, the high cost of inspections limited their abilities to complete these inspections on a regular basis.
To overcome this, Renfrew acquired a Deep Trekker DT340 pipe crawler. Deep Trekker CCTV crawler vehicles are entirely battery operated and do not require a dedicated truck to operate. This two carry-case system reduced the barrier to purchase a robust and capable system, with a lower up-front and ongoing cost in comparison to a typical CCTV inspection van.
Read the full story at www.deeptrekker.com/storm-water-cctv-inspection or call 519/342-3177.
Adjustable risers streamline paving operations
Problem: Superintendent David Ramsey of Lower Allen Township Authority, Pennsylvania, needed an adjustable riser to accommodate the various manhole dimensions in the sewer system on short notice. The manhole raising solution needed to be quick to install, sturdy and reliable, and of course cost-effective. “The single-piece risers were just a solid ring that couldn’t be adjusted, so all that held them in place was the new paving,” Ramsey says. “Often that wasn’t enough, so they’d rattle or get loose after a few months. We also had to keep an eye on them as the paver passed over, which was tedious.”
Solution: We were actually introduced to the American Highway Products risers in 1997,” Ramsey explains. “And based on the way our risers at the time were performing, they seemed like a good option to explore.” The pivoted turnbuckle risers can be ordered in very fine size increments, they expand and lock into place, and they’re custom made for each order, so diameter and thickness are always suited to particular utility frames and paving thickness.
Result: “Just recently, we had a 60-day window turn into a seven-day window,” says Ramsey. “So we put a rush order in on a Tuesday, and had our risers by Friday afternoon. That was very helpful.” 888/272-2397; www.ahp1.com.
CCCP used to rehab large culverts under high-traffic roadway
Problem: Aware of aging and deteriorating infrastructure, the city of Aurora, Colorado, contracted with Wilson & Company Inc. Engineers & Architects to conduct a comprehensive condition assessment of their corrugated metal pipe (CMP) stormwater infrastructure and assess various rehabilitation methods based on a set of specific criteria with regard to hydraulic capacity, load capacity and impact on the environment and traveling public. Two 96-inch CMP culverts under a major arterial roadway at the intersection of Louisiana Avenue and Biscay Street were found to be severely deteriorated and deemed to be in imminent danger of failure.
Solution: ACE Pipe Cleaning, a certified applicator of CentriPipe from AP/M Permaform, began the rehabilitation process with cleaning, invert repair, void grouting, storm flow diversion and sandbagging to ensure any large storm runoff wouldn’t flood the nearby neighborhood. They then applied the fine-aggregate cementitious CentriPipe liner in 1/2-inch passes to attain the engineered design thickness.
Result: CCCP proved to be a viable and cost-effective rehabilitation method for the large-diameter CMP. The minimal footprint enabled it to be installed without disrupting traffic. 800/662-6465; www.centripipe.com.
Lightweight grade rings a fit for off-road manholes
Problem: The District of North Vancouver, British Columbia, faced a problem in spring 2015 when they were tasked with the rehabilitation of existing manhole grade rings that were located off-road, in remote easements. They had a list of approximately 50 manholes that required attention and using a traditional concrete grade ring system made this project look daunting.
Solution: The district had heard about the expanded polypropylene PRO-RING system from Cretex Specialty Products. It meets AASHTO M306 for HS-20 and HS-25 traffic loading to withstand repeated impacts without damage, and is resistant to many chemicals. A traditional concrete grade ring would require several men or equipment to lift, while a 6-inch-thick PRO-RING weighs just 14 pounds. The entire ring system is assembled and bonded together in minutes using a construction adhesive/sealant to create a watertight, testable system. It is available in round, square and rectangular shapes.
Result: The PRO-RING proved to be effective in this application, allowing crew members to easily handle and install the rings without risk of injury. It enabled the district to spend less time on the job site, use less material, and use a smaller crew. 800/345-3764; www.cretexseals.com.
PVC liner used to rehab multiple manholes damaged by sinkholes
Problem: Municipal Utility Districts around the Houston, Texas, area were discovering sinkholes in the ground surrounding manholes. Hydrogen sulfide gas from force main discharges was causing the problems. Inspections determined that the integrity of the manholes was compromised and was quickly deteriorating, causing dirt and ground water infiltration that in turn caused excess debris to enter into the wastewater treatment plant.
Solution: A corrosion-resistant Danby PVC Liner was used to rehab the manholes by excavating out any remains of the manhole below the base while installing a liner plate for trench safety. The manholes were designed with 1-foot thick walls that had double mat No. 5 rebar installed, a minimum 5,000 psi concrete and lined with Danby PVC corrosion-resistant modular panels. An HDPE force main drop was also designed and installed. The manhole lids are designed for HS20 load and were also constructed and lined using the Danby PVC liner to provide the corrosion-resistant protection necessary for a manhole with a force main. The liner easily accommodated the depth, shape and even the lateral connections found in these manholes.
Result: The liner and panels help produce structurally sound, corrosion-resistant reconstructed manholes and manhole lids. 281/598-1126; www.danbyrehab.com.
Access assemblies enable smooth pavement
Problem: In the city of Elmira, New York, the dips, raises and cracking in the streets, especially in the areas surrounding manholes, were garnering some bad press. Craig Southard, senior engineer for the city of Elmira, hoped to find a solution that would also increase the life span of the pavement and make maintenance of city streets less labor-intensive.
Solution: He learned about SELFLEVEL access assemblies from EJ and ordered seven units. Judson Street, a street that would receive heavy traffic as the detour route for a major city thoroughfare, was selected as the test site. The SELFLEVEL eliminates steps that are par for the course with a typical one-frame assembly, such as measuring to ensure the frame lines up with the existing curb line, and shimming the frame to match the pitch of the road. The immediate result after installation is a smooth street. Even after a winter of continual freeze-thaw cycles, the street will remain smooth as the covers move with frost heaves to match the pitch in the road. The unit can be used for either new installations or retrofits.
Result: “It will save us money long-term, and will save us on maintenance, too,” Southard says. “It’s definitely a labor reduction internally of at least 50 percent. There’s also no need for extension rings.” 800/626-4653; www.ejco.com.
Plugs allow company to divert flow in order to rehabilitate manhole bench and channel
Problem: While performing the rehabilitation of sewer manholes in Baltimore County, Maryland, MIDAS Companies had difficulty controlling the flow while trying to rehabilitate the manhole bench and channel.
Solution: MIDAS brought this issue to Logiball to see if they had a large flow-through plug that could provide an easier way to control the existing flow in order to allow a more efficient rehabilitation of the manhole bench and channels. Logiball proposed its Type “D” Flow-Thru Plugs. The double-action bladder allows for the inward bladder to seal against the pump suction hose or bypass pipe while the outer bladder seals against the host pipe wall.
Result: Use of the plugs allowed for a quicker and safer diversion of flow while performing the rehabilitation of the manhole bench and channel. 800/246-5988; www.logiball.com.
Tool saves city time and money on water services repair
Problem: The city of Van Wert, Ohio, needed to replace the water services at a busy intersection, which included drilling 28-inch-diameter holes through 12 inches of blacktop. The project needed to be completed at the same time as another road closure, which put pressure on the city to complete the project as quickly as possible without having to rent or buy new equipment.
Solution: Through the street department, the city had access to a Mr. Manhole Six Shooter Gold Series tool that could cut the 12 inches of blacktop in just eight to 10 minutes. After the initial cut, it took just under two hours to excavate the holes so the city could perform the work on the water services. As an added bonus, the circle cut meant that the road is much less likely to split or crack, potentially saving the city thousands of dollars in damage.
Result: Incorporating the tool ensured that the project was successfully completed on time and within budget. The workers and the water superintendent of Van Wert have said the Mr. Manhole tool made the whole project easier, and they were very pleased with the results. 419/741-9075; www.mrmanhole.com.
Epoxy and adhesive provide transition between T-Lock and concrete manhole
Problem: Two manholes at the Los Angeles County Sanitation District’s Joint Outfall “G”, Unit 9 Trunk Sewer Rehab Phase 4 Project required epoxy coating of the base/bench with reliable connection to the previously installed T-Lock PVC liner. Standard epoxy resins couldn’t be used, as they don’t adhere to PVC materials.
Solution: Neopoxy International recommended using a combination of solvent-free PVC adhesive/primer and hand-applied epoxy resin NPR-5305.
Sancon Engineering applied a 1-inch-wide strip of PVC adhesive on the low edge of the T-Lock sheet. The next day, benches were coated with high-strength, corrosion-resistant epoxy NPR-5305, overlapping the PVC adhesive strip. That epoxy coating bridged the PVC material with the concrete manhole floor.
Result: The combination of PVC adhesive and NPR-5305 epoxy resin created a reliable transition between PVC material and concrete structure. 510/782-1290; www.neopoxy.us.
Resin used to repair storm drain manholes
Problem: Sinkholes had developed around storm drainage manholes in grassy areas of a military housing subdivision in Richmond, Virginia. Besides being unsightly, this posed a danger to neighborhood children. Flooding the sinkholes identified infiltration points further up the structure. The connection of the inlet pipe from the surface catch basin and the connection of the storm main near the bench were the source of most leaks. These connections have brick aprons that have been surface sealed. There were no rubber boots present. Water leaked between the bricks through cracks in the surface seal.
Solution: The crew injected Prime Resins Prime Flex 920 through the manhole wall to fill voids and create a watertight curtain. Prime Flex 920 is an expansive hydrophobic polyurethane resin that forms a watertight mass. The grouting was done from inside the manhole because the repair locations were so deep — as much as 20 feet from the surface. Technicians repaired wide gaps around the main connection by soaking oil-free oakum with hydrophilic Prime Flex 900 XLV and pushing it into the gaps to seal the openings with a bond to the wet concrete.
Result: The crew tested their repair by flooding the sinkhole again and saw no infiltration. The contractor completed the repairs with 8 gallons of material. 800/321-7212; www.primeresins.com.
Structural polyurethane liner proves itself in demonstration
Problem: Mishawaka, Indiana, was removing and replacing existing pipelines and manholes in a densely populated area of the city. Conco Spray Solutions was subcontracted to rehabilitate the manholes. Jennifer Hoop, Conco president, believed Sprayroq could be of great benefit, and wanted to prove it though a demonstration. Hoop proposed that the city allow Conco to apply polyurethane lining material to one manhole scheduled for demolition, to demonstrate its strength and structural rehabilitation properties.
Solution: Conco was allotted a manhole with severe structural issues, inflow and infiltration. Following two hours of light pre-lining prep work, the old brick manhole received a 250-mil lining of Sprayroq SprayWall structural polyurethane, completed in a single pass in one hour. The manhole was returned to service immediately after the invert was sprayed.
Result: The city was impressed with the speed and application of the product, and its ability to provide savings in the quick return to service and true structural properties. Mishawaka recognized its viability for future rehabilitation and protection projects. During the manhole demolition, an excavator with an operating weight of approximately 65,000 pounds, ground pressure around 8.82 psi and bucket breakout pressure of 39,000 psi was used to subject the manhole to multiple hits. Even after this — with its brick structure crumbling — the lining material inside stood strong. 205/957-0020; www.sprayroq.com.