Discharge System Design & Testing

RMK Mixing Zone Study Discharge System


California, USA

Water management for the closed RMK mine requires discharge from the pit lake to control pit lake levels. The discharge is performed under an NPDES permit that was initially issued in 2007 and required a low-flow mixing zone study to demonstrate complete mixing according to the State Implementation Plan. SLR performed designed and performed the mixing zone study successfully in the first half of 2008.

Our role

  • Engineering and design of temporary/pilot discharge diffuser
  • Application and negotiation of NPDES Permit
  • Development and approval of workplan presenting test protocol
  • Implementation of low flow mixing zone test using rhodamine dye
  • Design and construction of full-scale diffuser based on mixing zone study results


  • Successful demonstration that permit conditions were met
  • Implementation of a unique discharge permit that is based on proportioning discharge flow to the flow of an intermittent stream
  • Control of the pit lake level

Want to know more?

If you have any questions, or would like to discuss a project, our team would be happy to hear from you. Find out more