Operated by Pierce County Recycling, the Silver Springs Organics (SSO) Commercial Composting Facility near Rainier, Washington, accepts various compostable feedstock including yard debris, pre-shredded yard debris, wood waste and food waste. Feedstock entering the site are characterized and weighed at the scale office, delivered to the tipping area, and then processed. Processing results in a wide assortment of odorous chemical compounds.
SCS Tracer, a specialty division within SCS Engineers, was retained by SSO to conduct an ambient odor study to determine what compounds from selected source components at the facility contribute most to the ambient odors, and what mitigation measures should be considered to reduce the ambient odor footprint.
A limited field sampling plan was implemented and the data collected were used to compile an odor emissions profile for each significant source found at the site. This emissions profile was then applied to dispersion modeling using approved modeling techniques to gauge the magnitude of potential off-site odor impacts.
Off-site impacts were estimated using the USEPA-approved AERMOD dispersion model to establish an odor footprint for the facility. Historical meteorological data representative of the area from Olympia, Washington, and the characteristic chemical species determined in field sampling phases provided data input for the model.
Finally, potential mitigation methods for control of off-site odor impacts were identified. These mitigation options include operational changes (turning piles at optimal times), managing the receiving area, roofing the facility and aerating the detention pond.