The expansion was designed to increase the treatment capacity from 3 mgd to 6 mgd and needed to be constructed on a very limited site area.  The plans called for construction of 11 new structures, including a 100 ft. diameter storage tank and a very large (200 ft. x 95 ft. biological treatment unit (BTU)). Ardaman’s exploration plan included 24 Standard Penetration Test borings from 20 ft. to 120 ft. deep.  The presence of clay layers prompted the need to recover relatively undisturbed (Shelby Tube) samples of the clay for detailed laboratory testing.  The laboratory testing program included a battery of soil classification and index tests as well as consolidation testing of the clay samples to measure compressibility of the clay.  Ardaman conducted bearing capacity and settlement analyses and predicted total and differential settlements for each proposed structure.  Consultation with the design team indicated that the predicted settlements for most of the facilities were tolerable and the structures could be designed with shallow foundations on properly compacted underlying sand. However, the settlements predicted for the BTU were deemed to be excessive, and Ardaman proposed to pre-load the area beneath the BTU structure to impact the anticipated settlement prior to construction, thus reducing permanent settlement to tolerable limits.  Ardaman prepared a pre-loading plan which called for mounding 12 ft. of fill over the BTU area to mimic the final loading conditions. 

The project design engineers were presented an Honor Award by the ACEC of Florida as part of their 2020 Engineering Excellence Awards program.