Process pond modifications to mitigate groundwater elevation increase

When rising groundwater elevations posed a potential risk to the integrity of existing geomembrane pond liners, Barrick Cortez, Inc. (Barrick) retained SRK for engineering modifications to the process ponds. 

SRK performed expedited project planning, geotechnical evaluation, water balance analysis, and engineering design to meet tight compliance deadlines. Key design elements included:

• Increasing pond surface area where possible and using engineered rock fills to raise the pond base elevations above the groundwater elevation and provide permeable, low compressibility foundations with materials available on the mine site
• Modifying pond geometries to enhance evaporation and allow ready conversion to Evapotranspiration Cells for future closure
• Integrating dewatering systems into backfill construction to supply relatively inexpensive groundwater elevation control capabilities
• Synthetic liner systems with leak detection for process fluid containment
• Pumps and piping to provide water transfer capabilities, operational flexibility, freezing mitigation, and operation in case of site power outages

In addition to performing CQA during construction, SRK worked closely with the client and the contractor to optimise the effectiveness and economy of design implementation. For example, SRK evaluated site hydrogeology and construction dewatering approaches ranging from wellpoints to sheet pile walls. Ultimately, the team used a coarse granular fill to backfill to an elevation sufficiently above the water table. The granular and design backfills were constructed in stages, while SRK monitored settlement. The settlement and construction delays were minimal and installing a high-cost construction dewatering system was avoided.

Dan Neuffer: dneuffer@srk.com



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