The Job
This sedimentation tank abandonment project is located in Stamford, Connecticut. As part of a water treatment plant rehabilitation project a 25,000sqft underground tank needed to be abandoned, and the concrete roof removed.
The geotechnical engineer required an average fill density of less than 60lbs/cuft to avoid settlement.
The Challenge
The lightweight fill material had to provide sufficient support for:
- approximately 4′ of compacted fill material, and
- a delivery truck loading dock, and
- a future building.
To reduce the risk of inducing settlement, the tank fill material had to provide 500PSF of capacity for future loading.
The Solution
CJGeo proposed 25lb/cuft permeable cellular concrete with an approximately 10ksf compressive strength to fill the structure.
CJGeo placed the 25lb/cuft CJFill-High Permeability (CJFill-HP) cellular concrete in daily pours up to 980CY. Lift heights were up to 36 inches thick.
The total project volume was approximately 5520CY. After the CJFill-High Permeability cellular concrete was in place, the roof was demo’d. The roof debris rests directly on top of the cellular concrete. The site was then brought up to grade with common borrow.
Any precipitation that permeates through the common borrow runs through the layer of CJFill-HP. Then, it flows along the sloped bottom of the tank to a daylight drain at the low end.
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