A WEB BASED PERFORMANCE MONITORING SYSTEM FOR AN ACID MINE DRAINAGE ROCK WASTE REPOSITORY

The Ruby Gulch repository at the Gilt Edge Mine Superfund site is a capped waste rock repository. Early in the cap design EPA recognized the need for a long-term monitoring system which should meet the following objectives: 1 Provide information on the integrity of the newly constructed surface cover and diversion system 2 Continually assess the waste's hydrological and geochemical behavior, such that rational decisions can be made for the operation of this cap and liner system 3 Provide easy access to information pertaining to the system performance to stakeholders 4 Integrate of a variety of data sources to produce information which could be used to enhance future cap designs. Through discussions between EPA, and Idaho National Laboratory a long-term monitoring system was designed and implemented allowing EPA to meet these objectives. This system is implemented as a web based workflow environment, and provides a cost effective manner to deal with massive amounts of data and information. The monitoring system integrates data from a set of 522 electrodes resistivity electrodes consisting of 462 surface electrodes and 60 borehole electrodes (in 4 wells with 15 electrodes each), an outflow meter at the toe of the repository, an autonomous, remotely accessible weather station, and four wells (average depths of 250 feet) with thermocouples, pressure transducers and sampling ports for water and air. The monitoring system has currently been in operation for over two years, and has collected data continuously over this period. Results from this system allow for autonomous performance monitoring through automated data analysis and report generation. Performance monitoring has allowed users to obtain insights into the diurnal variation in rockmass behavior, movement of water through the waste (allowing estimates on residence time) and is leading to a comprehensive model of repository behavior. The same infrastructure and approach has been applied to other sites, and can be extended to performance monitoring of natural attenuation and other passive remedial systems.