Dairy Creek Slide

Dairy Branch Annular Space Grouting

Charlotte, North Carolina

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The Job

CJGeo’s Dairy Branch annular space grouting project is located in North Carolina. Charlotte Water’s Dairy Branch Tributary Sewer project is an approximately $30mm capacity improvement project to address increasing population density.

The Challenge

As part of the project, the tunneling contractor mined a 430LF tunnel ranging from 58″ bore to a four foot arch. The carrier pipe was 36″ ductile iron, and required annular space grouting using a mix which wouldn’t float the carrier pipe, and would be able to entirely fill the tunnel at low pressure.

The Solution

CJGeo proposed an NCDOT approved cellular grout mix due to passage through an NCDOT right of way. This annular space mix design is weighs around 30lb/cuft, so falls withing CJGeo’s CJFill-Ultra Lightweight range. The tunnel was completely dry, so displacing water was not a concern. It took less than two hours to place all 275 cubic yards of grout into the annulus.

Peak pumping pressure was less than five psi. Complete water filling of the carrier pipe provided more than a two time factor of safety for buoyancy control. CJFill-Ultra Lightweight cellular grout is sometimes called foamed concrete fill.

Speak With An Expert

Facing a similar challenge to CJGeo’s Dairy Branch annular space grouting project? Give us a shout or shoot us a text. Click the state marker for the location of your project for contact info for the appropriate rep.