Problem
A Michigan natural gas company was installing a new distribution line of buried 24″ pipe to help bring additional service to customers in Grand Blanc, MI. The area they were installing had a history of excessive rainfall and high water tables that they were concerned could lead to soil disruption and long-term problems for the new 25 mile line. To combat this, they decided to use polyurethane trench breakers to help protect the new line.
Solution
R-Value Foam, a Michigan based specialty contractor, was contracted to build the trench breakers to help support and protect the distribution line. Trench breakers are built structures that are used in pipelines to help stabilize the pipe and trench, creating a wedge-shaped structure that minimizes soil settlement and erosion. To construct the trench breaker, R-Value decided to use the Strata-Fill 24-023 geotechnical polyurethane for a variety of reasons.
First, because of the size of the trench breakers, there was concern that polyurethane could cause high heat or even fires due to exothermic reaction. The Strata-Fill 24-023 system helped mitigate any fears due to its low exothermic qualities, allowing R-Value to construct the trench breaker without pause.
Secondly, there was concern of leaching chemicals into the groundwater. Strata-Fill 24-023 is environmentally inert, meaning it will not leach chemicals into water sources.
Results
“R-Value has had great success with the Strata-Fill 24-023 because of its perfect cream time, low-exothermic qualities, and inert nature,” stated Mark Benaske, President of R-Value. “These qualities allowed us to construct the trench breakers in less than ideal soil conditions, quickly, and without concern of high exotherm.”
The 9-foot-deep trenches average 3-foot width at the base and 10-12 foot width across the top. The trench breakers were constructed onsite, from 6 inches above the bottom of the pipe to within 2ft of the top of the trench. After the trench breakers were completed, the trench was then backfilled by the pipeline contractor.
In all, the natural gas company received a trench breaker system that will not break down over time and that adheres to the trench in a way that traditional materials, such as sandbags, never will. Additionally, polyurethane is less labor intensive and more time effective, causing minimum disruption to the project.
