Solutions for Challenging Manhole Rehabilitation Project
- Jan 6, 2022 11:21:00 AM
- Everett J. Prescott
In the spring of 2020, EJP's Team PPF partnered with environmental consulting firm Woodard & Curran to produce a solution for a complex set of problems with a wastewater treatment system at a shopping center in Hingham, Massachusetts. The system serves The Derby Street Shops, owned by a private retail space company with similar properties all over the United States.
After a thorough assessment, Woodard & Curran’s project team developed a plan to correct problems with sanitary manhole structures at the shopping center. These challenges included serious corrosion of the manhole structures, odor from hydrogen sulfide gases, and water infiltration in and around the manhole inlet and outlet pipe junctions.
Team PPF’s job was to develop a set of treatments to effectively respond to each of these challenges. The corrosion of the structures had to be repaired of course, but it was also vitally important to protect the manholes from the threat of ongoing corrosion. The unpleasant odor of the escaping gases needed to be eliminated. And, finally, the groundwater infiltration was causing an increased volume in the wastewater system. That increased volume resulted in costly and unnecessary treatment of the groundwater by the wastewater treatment system. The project also needed to be completed within budget, and finally a plan needed to be developed to complete the project with minimal disruption to retail traffic.
Due the COVID-19 pandemic, with many stores closed to retail traffic during the construction period, the project was able to proceed much more quickly than normal, and all three manhole structures were able to be repaired and rehabilitated.
The first step taken was the necessary rebuilding of the manholes. All the concrete structures had deteriorated due to the infiltration of winter road salt used in the traffic and parking areas around them. Once the structural repairs were complete, the leaks causing the stormwater infiltration issues needed to be sealed. This was accomplished through the use of a high performing moisture activated grout. The selected grout, formulated specifically for concrete structures, was chosen because of its ability to absorb up to 12 times its weight in water while forming a tough impermeable gel with strong adhesive qualities.
Following these two steps it was important to protect the manholes from future corrosion. To accomplish this, Team PPF lined the structures with an epoxy coating system formulated to provide up to 75 years of protection in highly corrosive sewer environments. The products were developed to solve issues with corrosion, microbial attack abrasion and sewer gases.
With the manhole structures effectively rebuilt, sealed and coated, a final step was taken to address the issue of water infiltration from the paved areas above and around them. At the top of each of the three structures, water inflow dishes were installed to catch unwanted inflow and prevent it from entering the manhole through the manhole lid. The dishes are commonly used to reduce the amount of stormwater entering the wastewater system.
On any project, one of the many factors evaluated at Team PPF is life cycle costing. When measuring the effectiveness of any solution, it is of vital importance to know its effective life. This requires evaluating not only the cost of repairs, but also how long they are expected to be last.
At the Derby Hill Shops, it was critical to take all these factors, and more, into consideration. In the end, teamwork and solid communication between Woodard & Curran and Team PPF provided a solution to a very complex problem. The goal of both parties was to develop and execute a plan that would not only solve the immediate problems, but would also provide long lasting value.
Formed in 2008, Team PPF, a division of E. J. Prescott, Inc. provides a unique combination of solutions combining industry leading technology with the creative talents and abilities of its team members. The skill set available at Team PPF includes planning and communication, custom fabrication when needed, identifying the appropriate product portfolio, and finally custom installation on the job site. The Derby Hill Shops solution provides a solid example of the teamwork necessary to identify challenges, develop and solid plan, and finally to execute the plan. Contact us today if you have any questions!