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Stormwater System Series - 3. Evaluate Sealing Options

Posted by Charlie "The Grout Geek" Lerman on Nov 21, 2023 10:00:00 AM

Banner - Stormwater System Series - 3. Evaluate Sealing Options

Body - Stormwater System Series - 3. Evaluate Sealing OptionsWhen it comes to sealing leaks in stormwater systems, one size does not fit all. Whether dealing with curb inlets, drop inlets, manholes, or culverts, the choice of sealing material plays a pivotal role in the success and longevity of the repair. Cementitious grouts and polyurethane grouts represent the main contenders in the field. Knowing when and where to use each is crucial for a sustainable solution.

Cementitious Grouts: Old but Gold?

Cementitious grouts have been around for quite some time and are often the go-to option for many maintenance teams. Composed of a mixture of cement, sand, and water, these grouts provide a robust but somewhat rigid seal. They are best suited for areas where minimal movement is expected post-repair, such as static joints or stable concrete structures.


  • Economical and readily available
  • Easy to mix and apply
  • Excellent for filling large gaps and voids


  • Limited flexibility; may crack under stress or movement
  • Longer curing time, delaying return-to-service
  • Potential for shrinkage, compromising the seal

Polyurethane Grouts: The Future of Sealing

Polyurethane grouts have emerged as a modern, versatile option for sealing leaks. These grouts react with water to expand, filling cracks and gaps with a flexible, water-resistant seal. They are particularly effective for dynamic systems that may experience ongoing stress or movement.


  • Excellent flexibility; adapts to structural movement
  • Quick cure times facilitate rapid return-to-service
  • Effective in a wide range of conditions and materials


  • More expensive upfront cost
  • Requires specialized equipment for application
  • Skill-intensive; necessitates trained personnel for effective application

Location-Specific Choices

Certain leaks necessitate specific sealing methods based on their location within the stormwater system. For example, curb inlets often fare better with polyurethane grouts due to the frequent movement from vehicular traffic. On the other hand, stable, non-dynamic structures like concrete walls may be adequately served by cementitious grouts.

Deciding Factors in Choice

When choosing a sealing method, maintenance teams should consider factors such as:

  • Type and location of the leak
  • Expected post-repair environmental conditions
  • Budget constraints
  • Availability of skilled labor and specialized equipment
  • Required longevity of the repair

Training and Expert Consultation

Given the complexities involved in choosing the right sealing method, training and consultation with experts in the field are highly recommended. Properly trained personnel are more likely to make the right choice the first time, reducing the risk of future leaks and subsequent repairs.

Key Takeaways

The choice of sealing method is a multi-faceted decision that requires a comprehensive understanding of the leak's nature, the system's requirements, and the pros and cons of available options. Regular training and expert consultation can go a long way in ensuring that maintenance teams are equipped to make the best choice for sustainable and effective leak sealing.

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Topics: All Posts, Seal Leaks, Municipal Resources