Granger was selected to construct this $30 million Digestion Facility across the street from the existing Genesee County Wastewater Treatment Plant.
The new plant processes sludge from the existing plant to produce natural gas in “digesters” that can be sold back to the Utility and used as a secondary
gas source for plant operations. Work consisted of constructing three (3) 45’x62’ digester tanks and one process building, and involved $8 million in self-perform concrete work.
The digester tanks required unique cone-shaped concrete bottoms that were 22’ deep with 45 degree slopes to help facilitate drainage and flow of the heavy sludge out of the tank, a highly technical concrete placement process.
The overall plumbness of the digester tank walls was critical to maintain strict tolerances necessary for the fixed dome tank lids used for two of the three tanks. Granger also managed the prefabrication process for the 45,000-pound steel lids, which were prefabricated offsite in sections and welded together
onsite prior to lifting in place. To help ensure tolerances were met, Granger’s in-house Visual Capture team utilized a LiDAR-equipped drone to scan the
top of the tanks and create a 3D model using precise data from the scan. This allowed the tank lid vendor to fabricate the lids from drawings that matched
the finished product rather than pre-built drawings.
The scope of work also included a new building to house the digestion related equipment, installation of sludge feed pumps, a fermenter, boiler/heat exchangers, gas handling equipment, extensive piping and modifications to the electrical equipment for the new process equipment, the instrumentation and control system and the heating and ventilating equipment.