Columbia, SC – In 2025, BLE conducted a comprehensive geotechnical exploration for the Lower Crane Creek Sewer project in Columbia, SC. This critical investigation supported the design of approximately 5,400 feet of new sanitary sewer line, ensuring a foundation for reliable and durable infrastructure.
Using an amphibious marsh buggy drill rig, BLE drilled 13 soil borings that revealed a complex subsurface profile. The soils ranged from topsoil and fill to clayey and silty sands, lean clays, silts, and partially weathered rock. Groundwater was encountered at the surface and at depths up to 14 feet, influenced by the proximity of Crane Creek.
Laboratory testing identified mild corrosivity concerns for underground infrastructure, guiding BLE’s recommendations for construction. Key design considerations included the use of shallow foundations with allowable bearing pressures up to 3,000 psf, removal of unsuitable soils, and proactive dewatering strategies to manage groundwater and maintain trench stability. While excavation of partially weathered rock was anticipated, it was expected to be limited.
To address buoyancy risks from high groundwater levels, sewer lines were engineered with specialized backfill and grading using engineered fill materials. Additionally, the site was classified as Seismic Site Class C, informing seismic design criteria to enhance structural safety. BLE’s thorough geotechnical investigation provided essential insights that enabled safe, efficient, and cost-effective design and construction. By addressing soil variability, groundwater control, foundation support, and construction safety, BLE helped lay the groundwork for a resilient sewer system that meets the community’s needs today and into the future.