Chambersburg Residence

Challenge:

A large sinkhole opened up adjacent to the secondary construction driveway at the residence. Along this driveway were geo-wells that were compromised by sinkhole activity. The sinkhole was 16’ in length, 12’ wide, and 18’ deep.

Solution:

Hi-Tech proposed to remediate the sinkhole by injecting high strength, expanding, structural polymer into the void resulting from the sinkhole. Crushed stone was added to build a structure of polymer and stone together. This method would stabilize the throat of the sinkhole as well as the void left behind. After stabilizing the base, we were able to fill the large void leftover by the soil erosion. We continued to inject in the same manner as the throat, in 4’ lifts, of stone and polymer together. Each lift covered an area of 4’ deep to create a new structure and allow ground water flow without deterioration of the injected area. Finally, injections were done around the bottom of the sinkhole and beyond the outside walls of the sinkhole itself to lock in the problem area at depth.

Results:

Since the material is liquid at first, it penetrated the micro voids in the stone layer and expanded in 3-5 seconds at a rate of 20:1. The polymer held the stone together and compressed it as it expanded, allowing groundwater to flow through the stone layer and drain into the sinkhole or “natural drain”. Soil was then placed over the stone layer and compacted. The area was ready for crew to work immediately following the injections and soil placement. This project took 2 days to complete.