Universal Journal of Geoscience Vol. 4(6), pp. 122 - 127
DOI: 10.13189/ujg.2016.040602
Reprint (PDF) (1640Kb)


Installation of Infiltration Gallery at Greens Creek Mine - Juneau, Alaska


Thomas M. Hanna 1,*, Eric Sundberg 2, Gabriel Hayden 2
1 Johnson Screens, Durango, Colorado, USA
2 Greens Creek Mine, Juneau, Alaska, USA

ABSTRACT

The Greens Creek Mine is located on Admiralty Island, near Juneau Alaska. It is one of the nation's largest silver producers, with a projected 10-year mine life. Bedrock in the vicinity of the mine consists of relatively impermeable argillites. The only reliable water source for the mine and milling operations is the alluvium along the narrow stream bed of Greens Creek. The original source water for the mine consisted of three wells competed in the shallow alluvium of Greens Creek. However, the wells were too shallow and became ineffective in providing an adequate water supply due to freezing in the winter causing aufeis conditions and sediment production at times when the creek was experiencing high run off. In 2009 the wells were replaced with an infiltration gallery completed in the stream bed that would not be affected by the bedload movement and freezing that would damage the intakes and reduce capacity in the winter months. Estimates of the production from a bed mounted infiltration gallery were used to determine screen length and configuration in the streambed to provide a minimum of 3,800 m3/day water supply needed by the mine. A Johnson Screens, Muni-pak screen was selected as the intake to address problems that might occur with excessive stream bed erosion that occurs during large storm events and provide filtration during periods of high flow and turbidity. The main challenge during the construction phase was to maintain the 3,800 m3/day flow to the mine and mill operations while decommissioning the old well system and installing the new infiltration gallery. During construction, Greens Creek was diverted and the infiltration gallery was excavated, installed in the streambed and connected to the existing stilling well. The new system has been operational for about 2 years without problems at a capacity of 3800 m3/day with minimal drawdown in the stilling well.

KEYWORDS
Aufeis, Alaska, Alluvium, Hydraulic Conductivity, Infiltration Gallery, Muni-pak, Streambed, Water Supply

Cite this paper
Thomas M. Hanna , Eric Sundberg , Gabriel Hayden . "Installation of Infiltration Gallery at Greens Creek Mine - Juneau, Alaska." Universal Journal of Geoscience 4.6 (2016) 122 - 127. doi: 10.13189/ujg.2016.040602.