Remediation and Closure Plan Implementation

Mount Nansen Mine Site

Project Highlights

  • The project is focused on building a positive legacy in the Yukon, including training and employment opportunities, revenue sharing, and close involvement with Little Salmon Carmacks First Nation (LSCFN).
  • Ensero successfully managed the health and safety risks associated with COVID-19 to continue environmental monitoring and revegetation trial activities in 2020 -2021.
  • The Preliminary Design Remediation Plan was reviewed by the Government of Canada and received acceptance to proceed to the next stage of design as of June 18, 2021.
  • Ensero obtained a Type B Water Use License from the Yukon Water Board on behalf of MNRLP on August 19, 2021. Ensero and JDS are currently building a water treatment plant at the Mount Nansen site with expected completion in March 2022.

The Challenge

Mount Nansen is an abandoned gold and silver mine located approximately 60 km west of Carmacks, Yukon. The mine was developed underground in the 1960s and 70s, and the open pit operated from 1996-1999. Operations were shut down due to poor recoveries, tailings dam geotechnical stability issues, and water license non-compliances. The Government of Canada sought a qualified firm to assume these liabilities at the Mount Nansen mine.

Mount Nansen Overhead View

The Ensero Solution

Ensero Solutions (Ensero) has a successful history and appetite for unique contractual approaches and business solutions that allow for streamlined delivery of environmental solutions. Ensero and JDS Energy and Mining formed a Joint Venture (JV) called the Mount Nansen Remediation Limited Partnership (MNRLP) to purchase the former Mount Nansen mine and assume responsibility for permitting and reclamation. The unique combination of Ensero’s successful experience in environmental assessment, permitting, and environmental remediation and operations along with JDS Energy and Mining’s experience in engineering, construction, and field operations, provided the Government of Canada with the confidence they needed to proceed. 

Monthly Environmental Monitoring at Mount Nansen 2021

In 2019, MNRLP entered into an agreement with Crown-Indigenous Relations and Northern Affairs Canada (CIRNAC) to remediate contamination from the previous mining activities at Mount Nansen.

Working alongside the Little Salmon Carmacks First Nation (LSCFN) and CIRNAC, Ensero (on behalf of MNRLP) is primarily responsible for developing and implementing the Remediation and Closure Plan and the associated environmental assessment and permitting. Ensero will also be responsible for Care and Maintenance activities at Mount Nansen until all permits are approved to undertake remediation and closure. The remediation project is expected to take approximately 7 years to complete followed by a period of monitoring and maintenance.

MNRLP’s scope of work under the reclamation plan includes:

  • removing all tailings, potential acid generating waste rock and other contaminated soil and backfilling them into the open pit;
  • demolishing the existing mine buildings and other infrastructure (mill, shop, camp and power distribution facilities) and placing the waste within the open pit;
  • installing an infiltration barrier engineered cover over the open pit;
  • removing the tailings dam; and
  • restoring the Dome Creek valley by rebuilding historic creek channels and revegetating the site.
Revegetation Activities at Mount Nansen 2021

During the Care and Maintenance phase, Ensero will design, build, and operate a water treatment plant to treat site water.

The final closure objectives for Mount Nansen are:

  • Protect human health and safety
  • Protect and restore environment including land, air, water, as well as fish and wildlife and their habitats.
  • Return mine site to an acceptable stat that reflects original, traditions, and pre-mining land use.
  • Maximize local, Yukon, and First Nation benefits.
  • Manage risk in a cost-effective manner.

For more information about the Mount Nansen
Please see and download the project summary.