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An existing concrete sump basin within the 3,200 ft square one story water treatment facility had settled approximately 12 to 14 inches relative to the surrounding floor slab. The structure was built in the 1980’s and settlement had been observed gradually over the past several years. The sump settlement had caused concern regarding settlement of the structure, concrete floor slab, and other existing equipment. WPC visited the site and observed continuous slab cracks extending from the doorway toward the inside of the structure.
The purpose of the geotechnical exploration was to determine the existing subsurface conditions at the site prior to the planned interior concrete slab and sump foundation repair. As access to sump location inside of the building was limited, our subsurface investigation was performed outside of the structure on the existing parking lot to establish a general subsurface profile. Our geotechnical investigation at the site consisted of two (2) Flat Blade Dilatometer Tests (DMT) close to the footprint of the exterior walls. The DMT soundings were terminated at a depth of 30 feet below the existing pavement surface. The Flat Blade Dilatometer Tests (DMT) were performed using the Marchetti dilatometer. The Marchetti dilatometer consists of a stainless steel blade with an expandable circular steel membrane mounted flush on one face. The steel membrane is expanded into the soil using nitrogen gas at 20-cm intervals.
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