TECHNOLOGY AND DESIGN ADVANCES IN PASSIVE TREATMENT SYSTEM FLUSHING

Abstract

A common goal of passive mine drainage treatment is the removal metals such as iron and aluminum from contaminated water. However, these metals form solid particles that can clog pipes and limestone aggregate, increasing operational costs and decreasing treatment system longevity. To combat this problem, a wide variety of flushing systems have been installed in passive treatment systems. Flushing systems usually consist of a network of perforated pipes buried in limestone, which drain via valved header pipes. Periodically, the valves are opened to allow large amounts of water to flush through the system and, ideally, remove accumulated solids. This theoretically extends the useful life of passive systems by restoring porosity. Unfortunately, flushing system design is poorly understood and most systems are not designed using scientific or engineering principles. Four existing systems were examined from an engineering standpoint and an engineering method for designing these systems was developed. The purpose of this paper is to provide a survey of flushing technologies currently being used, detail one method of using engineering principles to design flushing networks, and discuss the implications of this analysis on future flushing technologies. Additional