Integrating Carbon Footprint Analysis into the Sugar Creek WWTP Expansion Project

When complete, the Sugar Creek WWTP Expansion Project increases the capacity of a 90-year old facility from 20 mgd to 34 mgd in two sequential phases. Considering the uncertainty associated with rising energy costs, regulatory requirements for greenhouse gas (GHG) emissions, and the desire to be a leader in environmental stewardship, Charlotte-Mecklenburg Utilities (CMU) integrated carbon footprint analysis into the Project. This analysis determined the base case carbon footprint – a 20 mgd facility, and measured that against each of the incremental expansions - first to 28 mgd and subsequently to 34 mgd.Completing the carbon footprint analysis for the Expansion Project:Provides a baseline for GHG for potential regulatory requirements.Drives energy optimization and energy efficiency into the design process.Considers GHGs in the alternatives evaluation.Quantifies a success story for CMU for this Expansion Project.This analysis looked at the relative GHG emissions of process configuration alternatives considered and discusses ideas for reducing the overall carbon footprint impact of the Sugar Creek WWTP expansion. In addition, this paper quantifies the GHG emissions related to wastewater process components in general.As a result of the Sugar Creek WWTP Expansion Project's energy efficiency initiatives, CMU avoids an estimated 1,595 metric tons of carbon dioxide equivalent emissions by 2014. Reduced emissions continue to increase as influent flows increase over time, thus further reducing CMU GHG emissions on a unit flow equivalent basis. Continued expansion to the Sugar Creek WWTP West Side process facilities can be expected to reduce GHG emissions by nearly 30% (over alternative locations for treatment) by 2034. As expected, indirect emissions associated with electricity purchases comprise over 80% of the overall emissions for the Sugar Creek WWTP. Thus, the most significant impact that CMU can make is to continue to focus on energy efficient design and operation.