a. Construct and commission a new 1.3-million gallon, cast-in-place concrete, anaerobic digester with a vertical mixer mixing system (new digester). b. Install and commission new digester support systems including, but not limited to, a new spiral heat exchanger, hot water pump and piping, digester sludge recirculation pump and piping, grinder, and associated control valves. Install and commission new redundant digester sludge recirculation pumps for the existing Digester Complex 2 (DC2) digesters 1 and 2. c. Construct digester gas system improvements including, but not limited to, new digester pressure relief and vacuum valves, foam separator, moisture separator, gas flow meter, isolation valves and piping associated with the new digester. d. Construct a new access bridge from the DC2 control building to the new digester. e. Modify the existing DC2 digesters, including, but not limited to, adding fall protection tie off anchors at roof access hatches, access modifications to the digester overflow box, replacement of existing overflow isolation slide gates with new knife gates, and installation of new digester gas isolation valves.
