Integrated Water Management Using Remote Monitoring for an Open-Pit Limestone Quarry

Engineered water management is crucial to development of a long-term strategy that emphasizes safety and efficiency. Key factors include characterizing groundwater flow direction and volume, characterizing interaction of surface water and groundwater, and operating constraints as the mine pit develops. Advances in remote monitoring allow for monitoring of flow rates and water levels, during planned or unplanned flow events, and permit robust analyses of the groundwater-surface water flow system around mines.

This paper presents the analysis of future pumping rates and volumes for an open pit mine located in an area of outcropping formations and faults. Pit lake levels are largely a function of groundwater inflow, pumping, and precipitation. Important factors relating to water management at this site include:

 

• Historically, pit water levels were monitored periodically, but recently water levels and discharge flow rates have been remotely monitored, continuously.
• A pit lake pump-off test was used as an areally extensive aquifer test to provide valuable data on the hydrogeologic properties of the groundwater system.
• Pit lake water is discharged to a nearby creek and is hypothesized to be re-infiltrating and reporting back to the quarry.
• Data from the transducers were communicated wirelessly to a database. This approach, though more costly than manual data collection, provided continuous water level and flow data even during unexpected events, without setting foot on the site.

The modeling analyses included calibration to pumping tests, implementation of pit progression, prediction of stream leakage for various outfall configurations, and analysis of seasonal and storm events on groundwater flow patterns and pit inflow rates. The results of this analysis were used to reduce pumping and related costs by approximately 30% and plan for future dewatering requirements under normal and extreme precipitation events.