An interior elevator pit needed for ADA retrofit in a multi‑level building, inside an old stairwell beside a load‑bearing wall on sandy soils. Conventional shoring wasn’t feasible indoors with tight footprint and headroom limits. Stable Soils of Florida was called in to assess and remedy the situation.
Initial Assessment
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Sandy, below‑water‑table soils at a planned 7 ft pit depth.
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Footing and slab at risk of undermining if excavated untreated.
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No practical option for sheet piling, slurry wall, or trench box.
Proposed Solution
Engineers designed a perimeter grout “box” using AP Soil 600, a low‑viscosity, single‑component permeation resin that bonds wet sands into a rock‑like, load‑bearing mass.
Procedures
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Lay out pit and grout‑box perimeter around the planned excavation.
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Drill and set probes to depths below the final pit grade.
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Inject AP Soil 600 while slowly extracting probes to form overlapping treated columns.
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Allow cure, then excavate the pit inside the treated zone.
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Grind exposed treated face flat and use it as the outer form for the concrete pit.
Results
Stable excavation adjacent to the load‑bearing wall with no observed soil loss.
Interior elevator pit completed without conventional shoring or large equipment.
Enabled ADA‑compliant vertical access using permeation‑stabilized in‑place soils.
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