Mining Projects

By applying unique solutions to increase the safety and longevity of our environment.

Coal Pier Sinkhole Grouting

The Job

With an annual throughput capacity of 48 million tons, Norfolk Southern’s Pier 6 at Lamberts Point in Norfolk, Virginia is one of the largest coal transloading facilities in the world.  As a round-the-clock facility built around precision logistics, there’s little tolerance for disruption or downtime.

The Challenge

When two sinkholes opened up at the end of Pier 6 adjacent to the bulkhead, railroad personnel reached out to an onsite maintenance contractor.  Steel plates were installed to provide temporary protection while a long term solution could be implemented.

The Solution

CJGeo performed DCP testing at the site in order to quantify the depth of voids below the pavement adjacent to the sinkholes.  The DCP testing showed that in addition to large voids visible from the sinkholes immediately below the pavement, there were large pockets of voids down to 15’ below the surface. 

CJGeo crews then used CJGrout 35NHV61, a hydroinsensitive, NSF-certified geotechnical polyurethane to fill all voids and restore stability to the area. The grouting work took five hours onsite to install 3400 pounds of material, with zero disruption to operations.

CMP Joint Sealing

The Job

Due to an oversight during construction, acidic groundwater at a coal mine in West Virginia was causing deterioration of 7′, 9′ and 10′ CMP bypass pipes adjacent to a coal stockpile. The pipes had been installed to bypass streams below the surface elements of the mine, but high iron content and low acidity of water entering the pipes caused the mine to have to treat the water which was supposed to be bypassed.

The Challenge

The pH of the water affecting the metal pipes was as low as 2.1. While typical chemical grouts have excellent histories resisting chemical attack at low pHs, low pH can affect the initial reaction. The owner and geotechnical consultant were also concerned about leak stopping work on the pipe causing water to flow outside of the pipe downstream to other areas which were yet unaffected.

The Solution

CJGeo worked with multiple potential grout suppliers to identify a grout which would not be affected by the acidic environment. A 120cps high expansion prepolymer was chosen due to its ability to react properly in low pH environments, and also for its low viscosity to help ensure good coverage.

A CJGeo chemical grouting crew completed leak stopping on 31 joints and 25 point leaks throughout 600LF of pipe over a period of two weeks, in addition to grouting a 1200CF cutoff wall to stop water migration outside of the structure.

Mine Shaft Abandonment

The Job:

The inverted pyramid concrete cap on a Civil War-era coal mine shaft collapsed catastrophically. The mine shaft was located in the middle of a suburban golf course in Richmond, Virginia. The collapse was due to deterioration of timbers lining the shaft through soft sandy soils. The soft sandy soils extended approximately 25VF down to rock. As the timbers deteriorated with time, the lost the ability to support the cap.

The Challenge:

The tunnel shaft was completely full of water, which was approximately 60 degrees. The area around the cap was very unstable, and did not facilitate top-down access over the mine shaft.

CJGeo’s Solution:

The repair was designed around drilling well casing at an angle to intercept the mine shaft at various elevations between the bottom of the cap and socketed down into the underlying rock. 3.5PCF hydroinsensitive polyurethane grout was chosen for its ability to provide the necessary structural support to the cap.

CJGeo performed pre-mobilization testing at our facility in collaboration with the design engineer to ensure that the grout would perform as desired. CJGeo placed polyurethane grout through approximately 15 different injection points, grouting from the top down. The end result was a plug extending at least 5′ into the shaft through rock, ensuring that the shaft through soft soils was completely stabilized.