Housing Authority of Russellville - Nicholasville, KY

Tuesday, May 13th, 2014 by John Siwicki

Challenge

The Russellville Housing Authority was established in the late 1950's. In the early 1960's they began constructing one-story, slab-on-grade duplexes with masonry block walls and brick veneer. Fill soil was placed over the original sloping ground surface to level the area for the construction of some of the first units. The floor slab of the unit in question rested on a layer of this fill soil. Over the years, the floor slab settled as the loosely-compacted fill soils consolidated. Differential settlements ranged from one to three inches, causing gaps to form between the floor and the base trim, interior doors to stick within racked door frames, and cabinets, countertops, plumbing fixtures, and the bathtub to settle and pull away from walls. The floor slab settlement even caused an exterior foundation wall to rotate outward. The Housing Authority compensated for the settlement over the years by adjusting or adding base trim and adjusting the doors and cabinets.

Solution

The original project specification called for 21 interior helical slab piers to stabilize and then lift the settled slab areas of one of the duplex units. Two additional helical foundation support piers were required to stabilize the exterior footing. Due to the rocky soil conditions and the limited working space within the unit, hydraulically-driven slab piers and foundation piers were selected as a more favorable alternative. Twenty-one (21) slab piers were installed in a grid pattern spacing of about 5 feet. The slab piers were driven individually to depths ranging from 8 to 12 feet, and each to a force of at least 9,000 pounds. The two exterior foundation piers were driven to over 45,000 pounds of force. The interior slab and non-load bearing interior walls were lifted back toward a level position and the outside corner and foundation was lifted approximately one-quarter inch. In all, 23 piers were installed in 6 days, which allowed the renovation project to proceed on schedule.

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