Projects

 

For the last 7 years, VESTRA has managed the investigation and remedial activities at the Bully Hill and Rising Star mines for Millennium Holdings LLC.  These mines are located in a remote region of Northern California with no infrastructure facilities (power, water, or phone service).  Site access is by boat or 4-wheel drive vehicle via logging road.

 

The Bully Hill Mine consists of two main portals and a large waste rock pile, and the Rising Star Mine consists of eight portals and one large and numerous small waste rock piles. The objectives of the ongoing activities are to eliminate 99 percent of the acid rock drainage (ARD) originating from the point sources and implement Best Management Practices (BMPs) to address the non-point sources. In addition to conducting routine maintenance and National Pollutant Discharge Elimination System (NPDES) compliance activities, the following remedial activities have been completed:

 

A 250-square-foot pilot passive treatment system was constructed on the Bully Hill waste rock pile to evaluate the feasibility of using sulfate-reducing bacteria (SRB) to treat residual ARD from the main Bully Hill portal. This pilot study is ongoing.

 

A 1,000-square-foot pilot passive treatment system was constructed on the Rising Star Waste Rock Containment Facility to evaluate the feasibility of using SRB to treat residual ARD from the main Rising Star portal. Reductions in copper, cadmium, zinc and aluminum concentrations exceeded 99 percent.  

 

Approximately 480 feet of new tunnel and a conventional bulkhead seal were installed in the new tunnel, and a remote bulkhead seal was installed in the main BH-3 tunnel.  Water captured behind the conventional seal is conveyed to the portal via a 4-inch high-density polyethylene (HDPE) pipeline.

 

Six small waste rock piles in the vicinity of the Rising Star Mine were consolidated into the main Rising Star waste rock pile. This pile was graded and capped with 60-mil HDPE and a vegetative cover.

In conjunction with the construction of the Rising Star Waste Rock Containment Facility, a diversion structure and bypass ditch were constructed to capture and convey water in the RS-5 stream channel around the waste rock facility.

 

Approximately 180 feet of the main RS-5 tunnel were rehabilitated and a bulkhead seal was installed. In addition, approximately 220 feet of new tunnel were installed, to intersect the RS-500 haul tunnel, and a bulkhead seal. Hydraulic pressure behind the bulkhead seals averages approximately 35 pound per square inch, or approximately 80 feet of water.   

 

The main Bully Hill and Rising Star waste rock piles were graded and planted to facilitate surface water runoff and minimize direct infiltration into the waste rock piles.

 

Prior to the installation of the Town Creek Diversion, the majority of the water in Town Creek flowed onto and infiltrated into the main Bully Hill waste rock pile. With the completion of the Town Creek Diversion, this water is captured and conveyed across the waste rock pile via a 36-inch underground pipe.

 

Overall, these activities have reduced metal loading from the Bully Hill and Rising Star mines by approximately 75 percent.  Further, the remaining discharges have been captured and, based on the pilot cell results, two full-scale passive treatment units will complete the bulk of the construction activities at these two sites. A Preliminary Engineering Evaluation of these passive treatment systems has been completed.