Virginia Annular Space Grouting

annular space grouting over lake for a pile-supported water supply line

Challenge:

1100 feet of pile-supported 34″ PCCP water line over a drinking water reservoir needed to be relined.  This Newport News, Virginia annular space grouting project was specified by the designer to use cellular concrete.  The relining contractor used 30″ welded HDPE for the slipline, which then required annular space grouting.

Limits:

There were multiple leaks at the joints between the PCCP sticks which had to be addressed prior to grouting.  Work was complicated by a seasonal light display, which limited access hours to the jobsite.  All work had to be performed over the drinking water reservoir.

The Solution:

Virginia annular space grouting using cellular concrete for HDPE carrier in PCCPThe designer specified 55PCF wet cast density cellular concrete for the annular space grouting.  Cellular concrete is highly flowable.  High flowability ensures low installation pressure, reduces flotation of lightweight carrier pipes, and ensures complete void filling outside of the host pipe.  Using cellular concrete for annular space grouting was specified by the HDPE slip lining pipe manufacturer.  The carrier pipe was completely filled with water during the grouting work.

Result:

CJGeo successfully completed this Newport News, Virginia annular space grouting project.  Due to failure of the PCCP internal concrete layer, grout injection had to be performed from the bulkheaded ends and also through the pipe wall, over water.  All venting was performed over water.  CJGeo completed the project without introducing any contaminants to the drinking water reservoir.

The 55PCF cellular concrete provided a break strength of approximately 700psi at 28 days.  Peak installation pressure was 18psi.