Coke Gas Pipe Fill
The Job
This coke gas pipe fill project is located in Middletown, Ohio, at Cleveland Cliff’s Middletown Works facility. Middletown Works determined that the coke plant would be more costly to repair than to replace, so elected to demolish the plant.
The Challenge
A demolition contractor working to dismantle parts of the onsite coking plant had to remove approximately 350LF of coke gas pipe. The work area is located in the basement of the coking plant.
Coke gas residuals will spontaneously combust when exposed to the air, but the pipe had to be cut into roughly 3′ pieces to remove it. The pipe fill grout had to:
- completely fill the pipe
- coat the residuals to minimize air exposure
- cut easily
- add as little weight as possible to the pipe sections
The Solution
CJGeo proposed using CJGrout-20SDB to fill the pipes. 20SDB is a 2lb/cuft rigid polyurethane foam, specifically formulated to flow long distances before setting.
CJGrout 20SDB is generated onsite by special polyurethane grouting rigs. The rigs have hoses up to 400 feet long, which convey the material from the grouting rigs to the placement area. For this coke gas pipe fill project, the crew had to run hoses approximately 250 feet into the building, down multiple stair cases. The hoses are lightweight and about 2 inches in diameter, so this isn’t a problem.
One of CJGeo’s polyurethane grouting crews was onsite for two days to complete the project. Once the coke gas pipes were filled, the demolition contractor cut them into 3 foot long pieces with traditional band saws bagged the sections, and removed them from site.
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25MGD Sinkhole Leak Grouting
The Job
An underground minerals mine started to lose up to 8VF per day of mine due to water infiltration. Investigation of an adjacent stream uncovered multiple sinkholes which had opened up where the stream crossed a fault. Two sinkholes were adjacent to bridge abutments of a public road, which served as the sole access for multiple homes and farms.
The Challenge
Mine personnel started to self-perform chemical grout in some of the sinkholes. Due to the slow rate of grout installation relative to the water flow, the self-performed grouting was unsuccessful.
Due to endangered fish habitats within the stream, cementitious grouts weren’t allowed, and any chemical grouts needed to be certified for potable water use.
The Solution
CJGeo mobilized two polyurethane grouting crews in the third week of the Covid-19 pandemic to the site. To facilitate safe access to the site, all grouting was performed from aerial platforms reaching out over the work area.
During the grouting process, multiple additional sinkholes opened up; CJGeo would seal one sinkhole, and an adjacent soil filled feature would blow out. Super sacs of aggregate were dropped in the sinkhole throats to fill the bulk of voids, and then polyurethane grouting was performed below the super sacs.
Using nearly 50,000 pounds of CJGrout 35NHV61, CJGeo was able to slow the leaks to the point where no additional sinkholes formed, and the mine’s pumps were able to dewater the facility.
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Coal Pier Sinkhole Grouting
The Job
This pier sinkhole grouting project by CJGeo is located at the mouth of the Elizabeth River, off the Chesapeake Bay. 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 trans-loading facilities in the world. As an around-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 hydro insensitive, 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.
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Acid Drainage Grouting
The Job
This acid drainage grouting project is located in West Virginia. A 72″ CMP stream diversion pipe under a coal stockpile at a coal mine in West Virginia was experiencing acidic water infiltration. This was causing bypassed stream water to become acidic, so regulators required all of the stream flow to be pumped to treatment ponds and treated. This was expensive, and the flow volume was greater than the design capacity of the treatment system.
The Challenge
Access was quite challenging. The pipe was either 700LF or 1300LF from the nearest access points to the farthest grouting location. Additionally, the infiltrating water was pH 2.
Due to location, all personnel had to be MSHA 40 hour trained, and the company registered as a mine contractor with the state.
The Solution
CJGeo recommended a hydrophobic prepolymer chemical grout with an extensive performance history in high acidity environments. CJGeo crews sealed a combination of 20 joint leaks and point infiltration sources using the prepolymer chemical grout.
To address acidic water migrating through the stone dust backfill outside of the pipe, CJGeo crews then grouted an in-situ cutoff wall in the trench just downstream of the lowest leak using permeation grouting. Permeation grouting is optimal for creating small footprint cutoff walls because it typically doesn’t require large equipment. The mine operator installed two dewatering wells immediately upstream of the cutoff wall to intercept and pump out the acidic drainage, to keep it isolated from the stream water.
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Tub Crossing Repair
The Job
This tub crossing repair was done for a short line railroad in New Jersey. The sandy soils of South Jersey are great for growing produce and mining pure silica sand. While most of the produce is shipped by truck, a lot of the silica is shipped by rail. The rails inevitably cross the roads, and many of the crossings are at grade.
The Challenge
A short-line railroad was experiencing significant settlement and pumping of multiple precast modular crossings in the Vineland & Millville areas. Each crossing saw significant truck traffic, primarily from aggregate mining, and also significant heavy haul rail traffic from transporting sand.
Voids below the panels were holding water due to poor drainage. Each time a truck or train passed over the panels, they deflected downwards. This deflection pumps base material out from under the crossing, causing settlement.
The Solution
Working with a rail maintenance contractor, CJGeo performed polyurethane grouting on a total of four precast tub crossings in the area, using CJGrout 40NHL. Each crossing repair took a single day. Polyurethane grouting allowed for the immediate resumption of automobile traffic, and rail traffic. Th CJGeo crew installed supplemental bolting to address the deterioration of the panels resulting from the extensive movement of the panels.
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Industrial Driveway Crossing Repair
The Job
This industrial driveway crossing repair project is located in Frederick, Maryland. MARC’s Brunswick Line’s Frederick extension passes through multiple industrial sites & driveways. This particular crossing served as the driveway of a ready mix concrete operation, so saw extensive high dynamic loading in a wet environment.
The Challenge
The repair had to be performed without disrupting either rail or industrial traffic. There was a four-hour window between the last morning train and the first evening train for performing the repair to the eight modular tub crossing panels. The settlement was up to two inches, with extensive spalling.
The Solution
CJGeo’s crew installed supplemental bolts due to replace the OEM center panel anchors, and then grouted the crossing in the mid-day window, without disruption to any stakeholder. The structural polymer grouting work took less than a day onsite. The work was done between the morning and evening commuter trains, but multiple freight trains used the crossing during the repair.
CJGrout 48NHL was the grout of choice. CJGrout 48NHL is formulated specifically for high, dynamic loading environments, such as rail crossings, and airfields. It provides superior bearing capacity, excellent resiliency to dynamic loads, and is great for correcting differential settlement between panels. Because it is relatively low mobility, CJGrout 48NHL is unlikely to affect adjacent pavement.
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Mine Shaft Abandonment
The Job
This mine shaft abandonment project is located in an area with a significant number of abandoned coal mines. 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 the 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, they 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.
The 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 hydro insensitive 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 CJGrout 35NHV geotechnical polyurethane 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. This plug ensures that the shaft through soft soils is completely stable.
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