Precious metal underground mine

Challenge

A confidential precious metals underground mine has operated at various production levels for over 80 years. The facility holds an NPDES Permit, authorising the discharge of wastewater to the local receiving stream via three outfalls. Due to closure of a mine tailings pond, one outfall requires relocation.

Solution

Following Idaho Mixing Zone Guidance, SLR performed a site visit to gather receiving stream information to determine the optimal outfall relocation. SLR utilised the EPA-approved CORMIX model to evaluate receiving water locations that would provide optimal instream mixing, achieve adequate dispersion for applicable effluent limits, and comply with Idaho Department of Effluent Quality (IDEQ) regulations. Results of the analysis were provided in a Final Report submitted to IDEQ for approval.

Our role

• Perform a site evaluation to support optimal outfall relocation.
• Compile and assess site data for inputs to the CORMIX model and evaluate subsequent model output that provided dispersion as a function of distance from the outfall.
• Final reporting and agency interaction.

Highlights

• Perform a site evaluation to support optimal outfall relocation.
• Compile and assess site data for inputs to the CORMIX model and evaluate subsequent model output that provided dispersion as a function of distance from the outfall.
• Final reporting and agency interaction.

Impact

SLR continues to support this facility with environmental permitting and compliance for the state of Idaho including site specific criteria development, wastewater treatment engineering, and other environmental services.