Ralph Silberstein: Do you live on top of the Idaho-Maryland Mine?
Many people in Grass Valley live and work over the Idaho-Maryland Mine without realizing it. A lot of information about the location of the two surface sites and the project features has been circulated, but not much has been shared about the sheer size of the project underground and how that may affect us.
The underground mineral rights of Rise Gold are massive, covering 2,585 acres. They extend north as far as the edge of Glenbrook Basin. To the south they run to Highway 174. On the east side they extend under the entire airport area, and on the west they run completely under Sierra Nevada Memorial Hospital.
Planned underground blasting, stoping and other mining activities will potentially impact anyone living or working in this area due to vibrations from the shock waves. The report on explosives that was submitted by Rise Gold estimates the impacts of blasting, with the goal of keeping shock wave velocity below a threshold of 4/10 inch per second (0.4 in/s) at neighboring properties. This is deemed as an “acceptable standard” because, according to the studies cited, “… human complaint factors were studied and it was determined that less than 8% of people would complain.” Note that, also according to the report, people can feel 0.1 in/s.
As unacceptable as it may be for those impacted, Rise claims that it can comply with this “acceptable standard” by using a time-phased technique of blasting and because the initial mining activity will be more than 500 feet from residences. However, once the mine is opened there is nothing stopping Rise Gold from drilling or tunneling anywhere within their mineral rights area and to within 200 feet of the surface.
Wells are of even greater concern. Due to dewatering of the mine, there will be lowering of the ground water levels in the area. The predicted amounts of ground water drop are detailed in a hydrological study based on a computer simulation. This study shows that dewatering will lower ground water levels 5 to 10 feet over a fairly large area between Idaho-Maryland and East Bennett Roads, and some other areas. Overall, of the 334 wells identified in the study, it specifically lists 152 that will experience a 1 to 10 foot drop in water levels.
What is worrisome is that this groundwater study depends on a lot of assumptions that mask the true risk. It depends on the assumption that the stratigraphy is uniform, that it conforms to their computer model throughout, and that no additional fractures, faults, tunnels, shafts or permeable rock features will be intercepted. But perhaps most concerning, the study assumes that the mining will be limited to a small portion of the mineral rights area, accounting for only one-third of the project lifespan.
I think the threat to wells extends far beyond the boundary of the mineral rights. And while the blasting is a problem for anyone near active mining, the potential loss of well water is a far greater problem. It was only a few years ago that, after reassurances of no serious risks to local wells, a permit to another mining company was obtained to reopen the San Juan Ridge Mine. Early operations hit a fracture, drained off the groundwater, and ruined 12 wells in the North Colombia area. Even today, Grizzly Hill School has to truck in water because their local wells remain polluted. We cannot rule out that a catastrophic event like that could happen here.
Needless to say, having your well level drop even one or two additional feet in the summer can be a make-or-break situation, and that is the smallest of impacts predicted by the study. When your well starts sucking air, there are no quick fixes! How would you establish a claim? Could you obtain compensation? How many months or years would it take to get a replacement well or get a NID connection? These are serious questions.
The reality is, the study acknowledges that at least 152 wells are going to be impacted and it does not say with any certainty that the dewatering and expansion of the mine won’t cause an even greater loss for well owners, or even a catastrophe like the San Juan Ridge Mine.
Simply put, this mine should not be permitted.
Ralph Silberstein lives in Grass Valley.
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