When the manholes along a busy stretch of Airport Road in the Town of Caledon were showing signs of deterioration regional leaders put a plan in place to combat the situation head-on and protect the manholes for years to come.
Like manholes of the same vintage across all of Ontario, this stretch was showing signs of corrosion and the Region of Peel, which manages the sanitary system for the town went searching for a rehab solution. The Region of Peel serves 1.4 million residents and approximately 143,000 businesses in Brampton, Caledon and Mississauga.
All of the manholes were showing signs of active infiltration at cracks and seams and the walls were showing signs of moderate to heavy deterioration due to hydrogen sulfide gassing. This was due in part to the manholes being part of a large forced main line with a great deal of turbulence leading to the deterioration.
After some footwork on their end, the Region’s Department of Public Works reached out to Parson Environmental Products, of Reading, Pennsylvania, in the United States to conduct a case study. With a distributor and contractor working in the vicinity, the project was handed over to Rain Drain Restoration, a Parson Environmental authorized contractor experienced in manhole rehab.
“Parson called Rain Drain Restoration as we are the factory trained contractor in the area,” says Peter Knight-Chevalier, owner of Rain Drain Restoration. “We determined that with the high corrosion and with the budget put in place by the region the best value was the Parson CA 100+.”
Parson CA Liner 100 + is s a high strength, fiber reinforced, micro silica enhanced pure fused Calcium Aluminate Cement and Calcium Aluminate aggregate mortar. This product was chosen because of its ease of application and for protection against future hydrogen sulfide attacks. Parson CA liner 100+ was also chosen for its compressive strength and ability to rehabilitate structural integrity. It hardens to 6,000 psi in 24 hours and 9,000 psi in 28 days.
The newly lined manholes are monolithic and the product has low permeability preventing future infiltration. An added benefit of the Parson CA Liner 100+ is that its mineralogy fights microbiologically induced corrosion (MIC) by inhibiting bacterial (Thiobacillus) activity, minimizing the production of sulfuric acid (H2SO4). With some of the manholes showing signs of MIC, and stopping the infiltration being a key goal, the Parson CA Liner 100+ was chosen by the manufacturer for the case study.
The project involved the rehabilitation of 12, 4-ft round manholes, that were an average of 18 ft deep. Four of the manholes had platforms installed 9 ft deep, adding to the complexity of the application because the platforms needed to be cleaned after the application of the CA Liner 100+. Eight of the manholes were in the roadway and four were along the road-side ditch meaning that traffic control was of the utmost importance to keep the Rain Drain Restoration crews safe during the prep, application and clean up process.
“In addition to the traffic, stopping the infiltration prior to lining was a priority,” says Knight-Chevalier. “The rain was relentless in 2013 [when the project commenced] and it took lengthy planning and coordination because the infiltration increases during these rain events. Once the manholes are lined and cured for 12 to 24 hours they are monolithically lined and water tight.”
After water blasting the interior of the manhole removing any debris that would inhibit proper adhesion of the Parson Environmental products Rain Drain Restoration crews applied Parson Seal-Tite, a polyurethane grout, to stop active leaks in the manholes. The grout was followed by the Parson CA Liner 100+, cementitious mortar applied via the spincasting method at a half to 1-in. thick and then brushed to finish.
To seal the new structural cementitious lining to the frame to create a flexible seal/joint between the new lining and the frame and cover, the crews applied Parsonpoxy FP, an epoxy/urethane hybrid seal. With the infiltration abated, crews used Parson Manhole Inserts to prevent inflow during rain events.
Knight-Chevalier is happy to report that the project, completed in 2013, was a 100 per cent success as evidenced by a return visit in 2017 to check on the quality of the work.