The Job
This Pennsylvania pipe abandonment project is located at a drinking water reservoir near York, Pennsylvania. As part of a dam reconstruction, the existing outfall pipe was specified for grouted abandonment.
The Challenge
The existing outfall pipe is 48″ cast iron pipe, and approximately 200 feet long. The pipe passes approximately 45 feet below the crest of the earthen embankment, concrete core dam structure. To ensure that the pipe would not serve as a conduit for water after abandonment, the specification calls for cellular grout with a maximum permeability of 1×10-6 centimeters per second.
During design, there were concerns about leaks in the pipe draining out some of the cellular concrete after placement stopped, but before it reached initial set. To address this, a secondary grouting program using chemical grout was designed to top off any void volume in the outfall pipe after the cellular grout set.
The Solution
CJGeo proposed using 60lb/cuft CJFill-Standard cellular grout for the abandonment. 60lb/cuft CJFill-ST exceeds the minimum compressive strength requirement, and has less than 1×10-6 cm/sec permeability.
CJGeo mobilized a dry batch cellular grout plant to the site to complete this Pennsylvania pipe abandonment project. The crew performed the grouting in fewer than two hours. The dry batch plant generates the 60lb/cuft cellular grout onsite directly from bulk cement powder.
Placement was through sacrificial grout pipes installed by the general contractor. The GC also constructed masonry bulkheads on both ends of the structure.
Exploratory holes drilled in the bulkheads the following day confirmed uniform fill, and no need for the secondary grouting work.
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