The Site is located in the Jamestown Mining District, at the northeastern end of the Colorado Front Range. The Jamestown Mining District extends across portions of the Lefthand Creek and South St. Vrain Creek watersheds. In this watershed, the tributary system begins with flow from the Little James Creek to James Creek to Lefthand Creek, which ultimately drains into South St. Vrain Creek. The majority of the mining in this area occurred around Jamestown, in the Little James Creek basin. The Bueno Tailings are located on a ridge northwest of Jamestown and approximately 3,800 feet southeast of the Bueno Mine. James Creek lies directly south of the Bueno Tailings, and Little James Creek is directly to the north.
The Site (specifically Bueno Tailings) is a Mixed Ownership site partly owned by the USDA-Forest Service and a private party. (According to county records, it was believed to be owned by Jamestown and a private resident. Recent title searches revealed both assignments were incorrect, and Jamestown does not own any of the tailings.)
The second portion of the Site targeted for a response action is another tailings deposit, which is located on Little James Creek approximately one third of a mile north of Jamestown. These tailings are commonly referred to as the Streamside Tailings. A smaller deposit is in the creek channel with the majority of tailings being impounded along the stream bank. This portion of the site is owned by a residential, private landowner.
Hazardous substances (heavy metals) in the tailings are released from the tailings impoundments into the environment including nearby residences and drinking water supply.
The Bueno Tailings deposit is migrating down slope from the ridge immediately above towards both James Creek and Little James Creek. The mass loading to the James Creek occurs immediately above the water intake for Jamestown, which occurs primarily during spring run-off and major rain storms. In addition, homes lie immediately below the ridge top where the Bueno Tailings are eroding down slope to the south (or into the James Creek drainage).
Streamside Tailings deposits outside of the impoundment are routinely eroded by normal flows in Little James Creek. The potential exists for a significant deposition of tailings in the town of Jamestown from the Streamside Tailings impoundment resulting from flooding in the Little James Creek. A engineering stability analysis (1/13/06) shows the tailings impoundment is stable. However, erosion along the impoundment slope face caused by surface flow and infiltration causes on-going releases, and it is reducing the stability of the impoundment.
On October 31, 2005, the OSC/ERRS mobilized to the Site to initiate the following Removal Actions:
The initial action implemented in October 2005 was to install approximately 200 feet of erosion control fencing (silt fence and straw bales on the southern slope of the Bueno Tailings impoundment. The purpose for this action is to reduce the discharge of tailings into Little James Creek and the associated water intake during the 2006 spring run off period prior to implementing the remainder of the proposed response action.
The current plan for the Bueno Tailings and possibly a portion of the Streamside tailings is to relocate the material to a location up slope and more easily protected from erosion. The proposed storage cell is located on the Bueno Mill and Mine property. Tailings placed here would be significantly removed from surface water and capped with an engineered cover. In the event that the first option can not be implemented, the second approach involves consolidating the tailings deposits at the existing Bueno Tailings location. This may include moving a portion of Streamside Tailings to the Bueno Tailings, and it would require moving the tailings now eroding from the Bueno Tailings deposit to the ridge top. Tailings on the southwest, south and north slopes below the Bueno pile would be consolidated to the top of the pile and the pile would be graded and capped with a soil cover and vegetated. In either approach, the extent to which tailings will be removed from the side slopes will be based on engineering feasibility, cost and protectiveness. The Streamside Tailings impoundment, if left in place will be armored to prevent erosion in a 100 year runoff event.
Final designs for the actions described above are being developed. Ground water monitoring wells will be installed to at the proposed storage location to establish a base line for water quality.
None at this time.
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