Sewer Collapse Sinkhole Repair

Lynchburg, Virginia

The Job

When the operators of a tire and auto shop noticed a sinkhole developing next to their building, they weren’t sure what to do. After an employee crawled into the hole and discovered that he could stand up underneath their building, the owner reached out to the city. City crews determined that a 20″ VCP combined sewer & storm pipe had collapsed under the structure, roughly 25′ below grade.

The Challenge

An on call contractor for the city installed a new manhole and rerouted the pipe around the building, but addressing the sinkhole was out of their businesses’s scope. The project manager reached out to CJGeo, who visited the site and recommended DCP testing to better quantify the extent of the problem.

The Solution

DCP testing showed that outside of the large hole on the surface, there was little deep disturbance. Working with the city’s consulting engineer, CJGeo developed a grouting plan to install two different CJGrouts; 20SDB in the bulk voids near the surface, and 35NHV61 for soil grouting to address voids within the underlying ground near the failed sewer line.

While onsite for just 6 hours, a CJGeo crew completed the work with zero disruption to the businesses’s operations.

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