Manuscript: New GHG methodology to quantify sewer methane

Introduction.  the Intergovernmental Panel on Climate Change (IPCC) has identified that wastewater in closed, underground sewers in the developed world are not a significant methane (CH4) source (IPCC 2006). Other greenhouse gas (GHG) protocols have followed IPCC's lead and have ignored sewer CH4. This simplification has been contradicted by research (Guisasola, 2008; Foley, 2009; Guisasola, 2009; Gutierrez, 2009; van Voorthuizen, 2011; Willis, 2012; and Liu, 2014) where significant CH4 emissions have been repeatedly detected from both pressure mains and gravity sewers. The Water Research Foundation's (WRF, formerly WE&RF and WERF) Conveyance Asset Prediction System (CAPS) project (WERF Project #U5R12) developed a methodology for estimating collection-system methane (CH4) on a sewershed-wide basis. The method uses hydraulic-model output at average flows, actual sewage temperatures and actual flow rates as input. A Knowledge Development Forum (a workshop that is not for CEU credit) entitled “Sewer-Methane GHG-Methodology Standardization” will be held on Saturday at WEFTEC-2018 in New Orleans. The forum objective is to drive toward WEF-industry consensus on a new greenhouse gas (GHG) accounting methodology for adoption by ICLEI, the California Air Resource Board (CARB), IPCC, and other protocols. This paper summarizes the method and provides specific guidance on its use for estimating sewer-CH4 generation. Copyright © 2018 Water Environment Federation