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Pipelines & Tunneling

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

HRSD 24″ Forcemain Abandonment

The Job

HRSD’s Virginia Beach Boulevard Forcemain Replacement project installed more than a mile of new pipe to replace an aging 24″ force main.

As part of decommissioning the original force main, it needed to be filled completely with grout.

The Challenge

Due to extensive widening of the roadway, the pipe was originally constructed alongside, extensive commercial and residential development, the number of access points needed to be as few as possible. This was driven by extensive structures over/adjacent to the old pipe, and a desire to reduce disruptions to adjacent stakeholders, and the risk of any utility strikes during access pit excavation.

The Solution

CJGeo grouted more than 7,000LF of the 24″ pipe over a period of four working days onsite. The pipe was completely filled, which was verified by uniform material venting from the far end of each run. Run lengths ranged from 450LF to more than 2000LF.

Tunnel Abandonment

THE JOB

A plumbing contractor hand tunneled 140LF of 4’x5′ tunnel under two apartment buildings near Boston, Massachusetts. In preparation for a renovation project, a structural inspection was performed. The structural inspection revealed the slab floors which were tunneled under were not designed as structural slabs. The structural engineer directed the property owner to immediately fill the tunnels to restore structural integrity.

THE CHALLENGE

The tunnel abandonment work had to be completed during the winter, and while one of the two affected buildings was occupied. The non-occupied building was also in the process of asbestos abatement and a full gut renovation.

Due to the plumbing running through the tunnels, an excavatable grout was required. Also, the grout had to be low exotherm in order to not affect the new PVC plumbing.

THE SOLUTION

CJGeo proposed polyurethane grouting for the tunnel abandonment. Polyurethane grouting can be performed in any weather, is low exotherm, and can be placed in very thick lifts. The specific grout chosen was a low exotherm bulk void filling polyurethane.

CJGeo mobilized a polyurethane grouting truck with more than 9000 pounds of polyurethane grout, due to the unknown exact volume of the tunnels. During an 8″ snowstorm, CJGeo abandoned both tunnels in a single day. The unoccupied building was grouted via holes drilled through the floor. The tunnel below the occupied building was free sprayed from inside the tunnel. All tunnels were kept under negative pressure ventilation in order to address installation odors.

CJGeo placed 4100 pounds of polyurethane grout into the two tunnels.

Communication Jack & Bore Grouting

The Job

The Sandston area, just outside of Richmond, Virginia, is at the crossroads of major north/south data transmission lines, and transoceanic data transmission lines. As a result, a number of large data centers are in the area or being planned & constructed.

The Challenge

As part of the construction of a new, multi-billion dollar data center, a utility contractor bored two, 48″ steel casings under a roadway & adjacent wet utilities for a road crossing. Each of the casings had up to 20 different PVC conduits held in place using casing spacers. The contractor needed a grout that could be placed at minimal pressure while ensuring complete fill without damaging the conduits.

The Solution

CJGeo mobilized a cellular grouting crew to the site and grouted both pipes in a single day. The peak grouting pressure was 5psi, and confirmation of fill was achieved when uniform cellular concrete was vented from the 12 o’clock position on the opposite end of each bore. 38PCF cellular concrete was used to achieve the design strength of 200psi at 28 days.

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