SFWMD C-44 Reservoir and STA Emergency Cost Estimate

The C-44 Reservoir and Stormwater Treatment Area (STA) occupies 6,300 acres of land, 6 STA cells, 32 miles of berms, 30 miles of canals, 56 water control structures, and other associated features, which represents a construction contract cost of $100M. During construction, there was severe erosion damage to berms and levies. SFWMD had issued Non-Compliance Notices to the construction contractor and attempted to resolve the problems. Still, there were disagreements about the extent of the damage, which needed to be repaired, and the associated costs.

SFWMD hired WGI to provide an independent assessment and Engineer’s Opinion of Probable Remaining Construction Costs (EOPRCC). SFWMD needed the assessment and EOPRCC on an emergency basis — within one month.

Given the vast area over which the erosion damage had occurred and the very short schedule, WGI used unmanned aerial vehicles (UAVs) to collect aerial imagery and topographic data to create a 3-D model. This as-built model was used for volume comparisons against design models created from the plan set. WGI’s innovative use of reality capture technology allowed us to collect the necessary data and complete the EOPRCC on time.

WGI’s civil and structural engineers performed site inspections of the berms, canals, and water control structures, then compared the construction progress with the Contractor’s Pay Application and determined the amount of work needed to complete construction and bring the deficiencies noted into compliance per the contract documents.

One component of the cost estimate was invasive vegetation control. During construction, miles of the berms were not stabilized correctly, and consequently, large areas became infested with invasive cogon grass. WGI developed a treatment plan and cost estimate to eradicate the cogon grass and replace it with native grass per the specifications.

WGI reviewed contract documents, interacted with SFWMD and CEI personnel, conducted site investigations, examined topographic data, and conducted a forensic review of the pay applications to compile the data and prepare the EOPRCC on time.