Monday 4:30 PM
Biosolids - Wastewater
Optimizing Digester Gas Utilization at the Thorn Creek Basin Sanitary District
The digesters at the Thorn Creek Basin Sanitary District were constructed between 1935 and 1967. One digester used currently as a secondary digester was due for replacement of its 75-foot diameter floating gas holder, since the existing cover was approximately 53 years old. The District incorporated review of floating and fixed covers into the design as well as optimizing the digester gas collection and distribution system. Review of plant-wide gas storage and utilization was an element of the design of the new cover. This analysis evaluated the use of a variety of digester covers including flexible membrane covers, floating type covers, gas holder covers and fixed type covers, as well as evaluating the transfer of gas between the digesters and digester gas fueled equipment. Evaluations indicated several improvements to the facility digester system could be accomplished as part of the project, which were designed to reduce additional capital costs. These included adding additional capacity to the gas conveyance system, reusing existing digester gas piping not in use and repairing existing gas piping supports. These modifications to the digester gas system resulted in the elimination of differential pressure alarms, reduced maintenance on the covers and provided operational flexibility throughout the digester gas system for future operations.
Moderator: Lou Kollias
John J. McDonnell - Thorn Creek Basin Sanitary District
Mr. McDonnell has over 34 years as practicing environmental engineer in wastewater and solid waste, including 6 years as District Engineer at the Thorn Creek Basin Sanitary District.
Mr. McDonnell holds a BS Civil Engineering from Colorado State University, a MS in Civil Engineering from Stanford University and is a Professional Engineer in Illinois.
James M. Kerrigan - Greeley and Hansen
Mr. Kerrigan has over 6 years of engineering experience in water and wastewater design and construction. He is currently a project manager at Greeley and Hansen, a leading environmental consulting engineering firm dedicated to the water and wastewater industry.
Mr. Kerrigan has served as project manager for a wide variety of storm water, water, and wastewater engineering planning and design projects for public and private utilities and agencies. In addition to these activities, he is also involved in design of odor control facilities at wastewater treatment plants, program management for large combined sewer systems, and engineering services during construction.
He has been a member the Water Environment Federation since 2006 and has been actively involved in numerous WEF and Young Professional activities. He has also presented several papers and has authored published articles at both regional and national levels.
Mr. Kerrigan received a bachelor’s degree in Civil Engineering from Napier University, Edinburgh, Scotland and is a registered professional engineer is the state of Michigan.
David V. Hobbs - Greeley and Hansen
Mr. Hobbs has over 38 years of engineering experience in water and wastewater design and construction. He is currently an Associate at Greeley and Hansen, a leading environmental consulting engineering firm dedicated to the water and wastewater industry.
Mr. Hobbs has served as project manager for a wide variety of storm water, water, and wastewater engineering planning and design projects for public and private utilities and agencies. In addition to these activities, he was one of the authors of the "Water and Wastewater Treatment Plant Hydraulics” chapter in the Hydraulic Design Handbook.
Mr. Hobbs received a bachelor’s degree in Civil Engineering from the University of Illinois, and is a registered professional engineer in Illinois, Indiana, Oklahoma and Indiana.