A change of mine: Consultant makes suggestions about Idaho-Maryland Mine

The reopening of the Idaho-Maryland mine is a hot topic in Nevada County following the end of the public comment period for the draft portion of Rise Grass Valley’s proposal. Grass Valley City Council spoke harshly about the mine from an adviser this week.
Photo: Elias Funez

An advisory group told Grass Valley City Council this week that the draft environmental impact report for the Idaho-Maryland mine has several technical deficiencies.

Jeffrey Harvey, senior and chief scientist at Harvey Consulting Group, LLC, highlighted a proposed 80-year permit for the mine, as well as water quality and emissions, during his presentation Tuesday to the council. He recommended that the county revise the draft EIR, recirculate it, and go through the public comment process again.

Mayor Ben Aguilar said the city is not ruling on the matter but chose to hire Harvey to analyze the document and provide appropriate comment.

Harvey informed the council that the property is within its land use zone and should have it reviewed before the Nevada County Board of Supervisors votes on it.

A vote by this board is not planned yet.

According to Harvey, Rise Grass Valley, the company that wanted to reopen the mine, bought Emgold’s land and mineral rights in 2017 and applied for a permit to reopen the mine for 80 years.

“The previous total of the city’s grants was only 20 years, which made a big difference,” Harvey said.

Harvey added that mine production is planned for 365 days per year and will involve the disposal of 150 tonnes per year of tailings from mines, with some backfill to be stored at mine sites and some exported to local construction sites.

The Harvey Group recommended that the Nevada County Board of Supervisors, which will decide whether to approve the mine’s permit application, reconsider the entire approach.

“We propose a 30-year alternative with 10-year environmental performance reviews and adaptive management as needed,” he said. “We also recommend reducing the farm size in half to 500 tons per day, which is still a sizeable operation. And we’re looking at operating hours from 7am to 10pm. We would only switch to daylight hours. The Centennial Site (10344 Centennial Drive) is to be backfilled with mine tailings, which is not really acceptable for this material. It really should be allowed as a standalone industrial project.”


Harvey said water tests should be done monthly and if the results indicate problems, they should be monitored more closely. Additionally, Rise plans to use diesel equipment in mines, although Harvey said underground equipment should also be electric as greenhouse gas receivers didn’t include a map of where they would be located.

“Their projected energy consumption is 50,000 megawatts for 80 years,” he said. “We studied the Nevada County Energy Plan and found significant conflicts.”

There are certain significant impacts on emissions. One requirement is for a consultant to confer with the Northern Sierra Air Quality Management District, although there has been no consultation with the district. A stormwater mitigation was well done, Harvey said, but it was only a preliminary hydrology report and needs a final review before operations begin.

There is a need for vibration monitoring for underground blasting, which should be adjusted as needed, Harvey said. A traffic rating is a new requirement of California’s Environmental Quality Act, and the draft EIR has undercounted trip generation by two-thirds, Harvey claims.

“Our recommendation to revise the DEIR of deficiencies and create a recirculated DEIR and go through an extensive public review process.”

Jarryd Gonzales, spokesman for Rise, said his company is confident in the report.

“We rely on the thorough analysis performed by Nevada County to produce a DEIR concluding that there are no significant environmental impacts — including local wells, air and water quality,” he said. “Rise looks forward to the district’s final EIR and ultimately a decision by the Board of Supervisors.”

William Roller is a staff writer at The Union. He can be reached at wroller@theunion.com

The deadline for public comment on the draft Idaho-Maryland Mine Environmental Impact Report has expired, although additional opportunities for public comment will arise in the future.
Photo: Elias Funez

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