RB Session 08: Fugitive Methane Investigation and Abatement

WSSC Water recently purchased an Optical Gas Imaging camera to help identify fugitive methane leaks around their facilities on an on-going basis. They are the first wastewater utility to purchase their own OGI camera. This presentation will discuss how they made the business case for purchasing the camera and how they plan to use it on a regular basis. Upgrading biogas to RNG quality for pipeline injection has become an excellent complement to the water reclamation portfolio of renewable products providing an additional, non-rate based, source of utility revenue while simultaneously reducing carbon emissions. While many utilities utilize digester biogas for cogeneration and thermal demands, many continue to flare excess biogas representing a significant waste of a renewable resource. For many decades, Pima County relied on cogeneration CHP while flared excess biogas as needed. That all changed in 2021 when a biogas upgrading facility was installed at the Tres Rios WRF. The 3-stage membrane separation process produces RNG and saleable environmental attributes while achieving greenhouse gas (GHG) emission reductions and generating annual revenues in excess of $5,000,000 for the utility. However, the installation of any new process always presents new challenges. The Tres Rios WRF has instituted a rigorous leak detection program for fugitive methane emissions to address facility worker safety. Reducing fugitive emissions not only ensures worker safety, but also helps prevents loss of potential revenues. To help achieve these goals, Tres Rios utilizes a variety of means for monitoring fugitive emissions including open path LIDAR for outdoor monitoring, acoustic leak detection for pressurized, piping networks, and optical gas imaging cameras for routine inspection of digesters covers and hatches, pressure relief valves and condensate drains and traps.