Stormwater Pipe Repair

Stormwater pipe stabilization using polyurethane grouting in Petersburg, Virginia

Problem:

Polyurethane pipe grouting repair in Petersburg, Virginia.

Polyurethane grout showing on surface from buried pipe repair.

The facility manager at a chemical manufacturing facility in Petersburg, Virginia discovered a large sinkhole adjacent to a containment structure holding a 10,000 gallon tank. The sinkhole appeared to extend far under the footprint of the containment structure, which was 20 feet by 40 feet.

An investigation of the surrounding area revealed a 36″ RCP pipe installed running under the structure.  Per the plans, the joints were not gasketed during installation.  The location of the sinkholes on both ends of the containment structure lined up with the path of the pipe.

Constraints:

The containment structure, which was cast-in-place concrete, was coated with a coating designed specifically for the chemical makeup of the tank’s contents.  Therefore, drilling holes through the floor of the structure to fill voids below it wasn’t possible.

Due to the size of the pipe, confined space entry would be required to address the pipe joint sealing and void filling.

Solution:

High density polyurethane grouting to seal the joints in the pipe and fill the extensive voids below the containment structure.  Confined space man entry was selected as the best way to access the work area to avoid having to drill through the coating system.  

The ability to park more than 200 feet from the work area was also advantageous, as there was extensive process piping in the work area.

Results:

Grout plug at bottom of sinkhole from polyurethane grouting through wall of underlying pipe.

Grout plug visible at bottom of sinkhole.

The CJGeo 207 polyurethane grouting crew performed confined space entry and polyurethane injection to seal the joints in the pipe.  Extensive voids were discovered under the structure, around the pipe.  Grouting was done to back pressure refusal from within the pipe.  Extensive extrusion of foam to the surface around the perimeter of the structure also confirmed complete void filling.

Dye testing was used to confirm the leaking pipe joints were sealed and the voids filled after the stormwater pipe repair work was completed.