Have a tricky pipe abandonment challenge? Don’t want to dig holes down the middle of a road every 100 feet to dump flowable fill into a pipe? We specialize in long run pipe abandonments. Whether it’s a 4″ conduit or a 96″ sanitary sewer, our project experience of thousands of miles of abandonment helps you reduce risk, reduce cost, and complete projects faster. CJGeo has abandoned up to 5600LF of pipe in a single stretch with no intermediate access points
25PCF wet cast density cellular concrete is the most common pipe abandonment mix. This yields an average compressive strength of 70psi at 28 days. Higher densities can be used to achieve higher break strengths if required by project conditions. However, density & cost are positively correlated; the lower the density, the longer runs are achievable per placement point, and the lower the cost per cubic yard in place. Unlike sanded flowable fill mixes, cellular concrete does not segregate, so high factors of safety aren’t required to ensure adequate bearing capacity and/or long term stability.
Placement Method for Pipe Abandonment
Depending on pipe diameter, slope, and existing access points, cellular concrete for pipe abandonment can be placed by dumping into manholes using a tremmie tube, or can be pumped. Tremmie placement into manholes is the most economical method, however relies on gravity to ensure complete fill, so is rarely used. Cellular concrete can easily be pumped 3000+ feet through abandoned pipes. Therefore, cellular concrete requires far fewer injection points than traditional flowable or pumpable fill.
We install both prepolymer grouts (expansive) and acrylic grouts (non-expansive).
There are two typical risks associated with traditional methods of pipe abandonment: incomplete fills due to the physical limitations of flowable fill, and those associated with access point excavation, such as utility strikes.
The risk from incomplete fills is primarily related to the difficulty of pumping flowable fill. Since flowable fill relies heavily upon water content to ensure flowability, it is particularly prone to segregation. This segregation can lead to aggregate settling out and blocking a pipe and effectively creating a plug which can’t be overcome by the pressure of the pump.
Since utilities being abandoned are typically colocated with other utilities, reducing excavation is almost always advantageous. Using cellular concrete virtually eliminates access point excavations due to very long pumping distances.
Because cellular concrete reduces the need for digging access points and the time it takes to perform abandonments, it tends to be significantly less expensive than traditional methods.
We perform turnkey abandonments; there’s no need for our customers to coordinate pump services, ready mix companies, etc.
Our customers are almost always amazed by how quickly abandonments happen compared to self-performing with flowable fill. That 3000LF of 8″ that the owner said needed an access point every 200LF? It’s just 18 minutes of pumping with 25lb/cuft cellular concrete from a single point.
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