Industrial Bakery, Chambersburg PA

Challenge:

A Large sinkhole opened at a truck garage road, exposing fiber optic line, requiring emergency remediation. Hi-Tech mobilized the day after call came in.

Settlement hole was 16’ L x 6’ W x 6’ D. The throat was the size of a basketball and was 15’ deep to a large crack in the rock where water and soil was escaping. This sinkhole has history of opening up for the past five years and had been previously filled with concrete several times with no success. Recent construction in this area placed a fiber optic line and electric conduit in a large trench as shown in the pictures. The fiber optic line is approx. 3’ below grade.

Solution:

A light weight, structural fix was needed that could have a quick turnaround to traffic. Using the stone/polymer method, ¾” clean stone was used to fill the throat in 2’ deep sections. These were then injected at depth with the light weight, hydro-insensitive structural polymer. This injection permeates the stone as a liquid, then expands quickly at a rate of 20:1 its original size. This method was done all the way up the throat and into the large settlement area. The material in the large void area was injected in a 2’grid pattern to densify polymer and condense stone together. The polymer does not saturate the entire stone area, but with a tight knit grid pattern, it creates force on all surrounding stone.

Results:

This is now a structural filter that water can’t break down. The stone/polymer method will allow water to flow through the rock that is condensed by the polymer at a slow rate rather than a rushing flow. This method allows water to drain to a natural drain in the soil without compromising newly placed materials on the surface such as pavement, dirt and grass or even a structure. By allowing water to flow to that natural drain we are not compromising soil around the fix. This drastically reduces or even eliminates further sinkhole activity in the influenced areas.