manhole relining in Whistler

Manhole Rehab for Proactive I&I Mitigation

The Resort Municipality of Whistler (RMOW), located in the Squamish-Lillooet Regional District of British Columbia, proactively addresses concrete corrosion issues within its sewer infrastructure through targeted initiatives seeking to combat concrete corrosion along the RMOW’s trunk main and extend the functional life of this essential infrastructure.

In addition to mitigating corrosion, the municipality’s initiatives also seek to eliminate odor within its sanitary sewer system.1

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In early spring 2023, residents complained of an odor inside their homes coming from sewer lines. The municipality acted to identify 11 concrete sanitary sewer manholes (on average 4-ft x 7-ft deep) along the trunk main as being significantly corroded over time.

These manholes had not previously been lined to seal or protect them from inflow and infiltration (I&I), a situation that ultimately led to their deterioration. Among these manholes, only one received a “good” rating, while the rest ranged from “poor” to “fair.” To address this critical issue, the municipality initiated a sealing and lining solution using Epoxytec’s high-build, high-strength structural liners.

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manhole relining in Whistler

Serving the water and wastewater industry for close to three decades, Epoxytec (a subsidiary of Tnemec Co. Inc.) manufactures and delivers proven products engineered to seal I&I throughout sanitary sewer collection systems. Epoxytec’s CPP product line provides structural epoxy lining solutions which are designed at specified thicknesses (125 mils minimum) to hold back low-pressure forces, such as I&I and hydrostatic pressure while also protecting the concrete substrate from biogenic sulfide corrosion. With the guidance of HDIM Protective Coatings, Tnemec Co.’s Epoxytec sales representative out of Western Canada, the project was in good hands and began to take form.

This RMOW project was situated in a small community with narrow streets, posing logistical challenges due to their location. Three of the manholes were located along a narrow park road adjacent to a golf course. The choice of Epoxytec’s lining method, a trenchless technology approach, was instrumental in mitigating disruptions to the local community when compared to alternative methods.

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To ensure the success of the project, experienced contractor, Stray Cat Industrial, was selected to manage all aspects of the project. Stray Cat Industrial Services is part of Epoxytec’s Certified Applicator Network (ECAN) and offers a wide range of services and skillsets, particularly in the field of manhole rehabilitation. The contractor specializes in rapid installations using innovative approaches to wastewater lining and its expertise was crucial in completing this application effectively.

manhole relining in Whistler

Additionally, Tnemec Co.’s Technical Service played a pivotal role in the project’s execution; their onsite presence during the project startup provided valuable insights related to the product and equipment used to line the sewer manholes.

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The project encountered challenging weather shifts, with cold and wet conditions prevailing throughout the duration. Snowfall was observed on multiple days, and temperatures ranged between 45 F and 60 F. Inside the manholes, temperatures remained low, hovering around 45 to 50 F, with high humidity levels at 80 percent relative humidity (RH). Stray Cat Industrial employed various tools and equipment to maintain the appropriate temperatures and spray parameters, including drum kits with heated blanket wraps, 4,000-watt Viscon in-line material heaters, and a Graco XP70 with 145cc lowers. These meticulous controls were achieved using the correct plural component setup specified by Tnemec Technical Service.

Before the application of the structural epoxy liner, preparation of the manholes was undertaken. A high-pressure water cleaning operating at 5,000 psi and equipped with a 0-degree tip was employed to clean the surfaces. Surface pH testing was conducted before and after the cleaning process ensuring the concrete achieved a pH level of 9 or higher. The International Concrete Repair Institute (ICRI) Concrete Surface Profile (CSP) comparators were utilized to confirm the recommended minimum surface profile, with the surface profile ranging from CSP 5 to CSP 9. Once the surface preparation and substrate restoration were completed, Epoxytec’s Series 451 CPP Sprayliner MH was then applied at a thickness of 125 to 150 mils dry film thickness (DFT). Once sprayed, the product cured overnight, even under the challenging cold and wet environmental conditions. The project was successfully completed within a span of 12 to 13 days.

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CPP Sprayliner MH is a high-strength applied and bonded lining solution for either new construction or deteriorated and fatigued sanitary sewer collection infrastructure like that of Whistler. The product uses advanced microfiber-reinforced polymer (FRP) technology and cures with enhanced mechanical properties. The material is formulated with high moisture tolerance and H2S resistance to provide a sealed I&I barrier protection. Blended with reinforcing agents and various microfibers, it is a two-component product that is spray-applied using a plural component heated spray application with Epoxytec certified applicators.

The primary objective of this project was to line the existing sewer main and manholes to restore and seal them. This would prevent future corrosion, thereby extending the lifespan of this critical infrastructure. In addition to accomplishing this objective, the application would play a significant role in reducing I&I in the sanitary sewer collection system, aligning with the primary goals of most I&I mitigation programs.

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The Resort Municipality of Whistler’s proactive approach to combatting concrete corrosion and eliminating odors within its sanitary sewer system has resulted in a successful outcome. The utilization of Epoxytec’s structural lining system, combined with the expertise of experienced contractors and technical support, demonstrates a commitment to preserving and enhancing vital infrastructure, even in adverse weather conditions.

This project not only restores the integrity of the sewer system but also contributes to the broader goal of reducing I&I, ensuring a sustainable and functional sanitary sewer collection system for the residents of Whistler for many years.

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1 https://www.whistler.ca/services/water-and-wastewater/Sewer-Odour-Corrosion-Control-Program/

Silvia Caputi is marketing manager at Epoxytec LLC, a subsidiary of Tnemec Co. Inc.