GTA has geotechnical engineering and construction testing services for 17 different projects at a Lancaster County manufacturing facility. The site is located within a carbonate rock environment with severe sinkholes, caverns, very erratic rock, and soft unstable soils. GTA’s involvement with the complex construction projects, all performed within very tight schedules, is an excellent example of GTA’s engineering expertise and client service.
Geotechnical explorations and recommendations were performed for six different building projects, with buildings that ranged in size up to a four-story, 360,000-SF building. Test borings and cone penetrometer testing (CPT) was performed up to depths of 75 feet within the soft, unstable soils. GTA designed specialty foundation and shoring systems, such as micropiles, compaction grouting, soil nails and soldier pile walls. GTA used extensive geophysical analyses, including ground penetrating radar, electrical resistivity, and terrain conductivity, to identify the potential for sinkholes and caverns. Geophysics were used for large tracts of land to identity concerns, as well as within existing buildings to identify areas of sinkholes and caverns below slabs and foundations.
GTA also entered a 50-foot-wide cavern located below an existing building to evaluate the stability and perform a survey of the dimensions. GTA provided recommendations and construction testing for use of low mobility grout to backfill areas of the cavern that were potentially unstable.
Construction observation and testing performed for this facility consisted of soil compaction, utility installation, cast-in-place concrete, footings, slabs, masonry, and structural steel. On numerous occasions, GTA provided recommendations for sinkhole repair within paved areas, stormwater basins, at utility manholes, within existing buildings, within trench excavations, and below foundations.