Optimizing Landfill Ground Water Analytes—New South Wales, Australia

Abstract

AbstractA study of analytes for ground water monitoring was conducted at 10 municipal solid waste landfills in northern New South Wales (NSW), Australia. From literature review, analytes were proposed and then approved by the NSW Environment Protection Authority (EPA) for initial ground water and leachate monitoring. Eight rounds of initial baseline monitoring using traditional geochemical analytes were conducted in uncontaminated ground water at a new, lined landfill. Four rounds of initial assessment monitoring were conducted at nine unlined or only partially lined old landfills. Analytes for the old landfills were selected with a health risk emphasis because ground water may already be contaminated.At the old landfill sites, analytes with values indicating contamination were often limited to one particular analytical group, although the analytical group represented differed from site to site. As a result, the most environmentally responsible suite of analytes for baseline monitoring is the traditional geochemical approach; free carbon dioxide for landfill gas; and organics in the form of volatile organic compounds for old landfills, but benzene, toluene, ethylbenzene, and xylene when wells are close to a new landfill. The current Subtitle D (U.S. EPA 1991) analytes proved inadequate. They would not have detected the majority of contaminants or contaminant indicators at the old landfills, i.e., organic nitrogen, ammonia, nitrate, iron, and manganese.After completion of initial monitoring at each site, reduced lists of analytes for ongoing monitoring were proposed and approved by the NSW EPA. The lists were based on literature evidence, contaminants, and contaminant indicators found in ground water at the old landfills, and in some cases leachate versus ground water concentrations. For the new landfill, the principle of limited analytes representing a broad range of analytical groups was used to assure precautionary environmental outcomes. At present‐day costs, cost savings for analyses alone at the new landfill are ÄD251, 160 over the 70‐year life of the landfill.