LESSONS LEARNED DURING A LANDFILL’S 10-YEAR STRUGGLE TO CONTROL LANDFILL GAS MIGRATION

摘要

Offsite landfill gas (LFG) migration was first discovered at the Brown Station Road Landfill, Prince George’s County Maryland, in the early to mid 1990s. And after a long 10 years, we can now report that the migration is finally under proper control. This paper chronicles our story with the hope that other landfill owners or operators would learn from our lessons and maybe manage their offsite migration problems in a more timely and effective manner. The impacted boundary measured about 1,000 feet, was only about 40 feet away from the compliance boundary, and was adjacent to several private homes. The paper discusses the immediate safety, regulatory, and legal actions taken to respond to the migration discovery. There were several preliminary findings that made the analysis fairly complex: higher methane concentrations further away from the waste footprint, a nearby underground natural gas line, and nearby marshlands. Moreover, Prince George’s County utilizes methane rich LFG at this facility to fuel an offsite 2.5 MW power plant (one of the first LFG-fueled power plants in the United States, installed in 1985), boilers that serve the heating needs of their onsite maintenance shop and an offsite 1,300 bed correctional facility, and more recently to fuel an additional onsite 4.2 MW plant. Adding further to the complexity, the landfill is affected by the Emission Guidelines and Compliance Times for Municipal Solid Waste Landfills (EG) which prescribes the operating parameters of its LFG collection and control system. All these factors taken together made for a challenging solution. Nonetheless, a relatively simple and cost effective solution was found only a year ago. It consists of a uniquely designed perimeter trench that contains certain state-of the- art features to allow for various levels of control. The design details of the trench, explanations of its unique features, and actual performance data are also presented in this paper.