The Gold King Mine Acid Drainage Spill

Transcription

1 The Gold King Mine Acid Drainage Spill Janick F. Artiola, Extension Water Quality Specialist Department of Soil, Water & Environmental Science What Happened? Impacts What can Be Done To Prevent This?

2 Flow Conditions: Moderate Spill Event Spill occurred on August 5 th, 2015 (<24h period) Three million gallons of Acid Mine Drainage Location: Cement Creek (Animas River tributary near Silverton)

3 Plume Acid Mine Drainage changes from reddish-brown to orange-yellow as the ph rises and Iron (oxides) precipitate

4 Mixing Plume Arriving at the San Juan River in Farmington, NM

5 Acid Mine Drainage Composition ~ 97% of the Mass ~ 1.5 % of the Mass ~ 0.07 % of the Mass

6 Dilution Spill was flushed from the Upper Animas River and diluted up to 150 times in ~24 hours San Juan River diluted the plume ~600 times in 24 hours Measurable impact in River Water Quality in the Animas River for ~7 days and ~two weeks in parts the San Juan River. (suspended lead) No Measurable impact in the Colorado River and Below Lake Powell. Plume Diluted 4000 times in 24hours

7 Impacts-Initial-People Potential Exposure Pathways to the Contaminants Include: Water: River, Wells Food: Agriculture & Ranching, Fishing & Hunting Water Users Along The Animas & The San Juan Rivers: Water Use Stopped Public Water Supplies Navajo Nation Communities (Upper Fruitland, Shiprock, Aneth) Irrigation Districts

8 Impacts-Initial-Environment Sediments Contaminated with Pb and As and other Potentially Toxic Metals such as Fe, Al, Zn,Cu Benthic Organisms Fish Lifestock? Wildlife EPA and CO Parks & Wildlife Reports(2016): Animas River Fish populations not impacted No substantial impact to BMI populations Some BMI with elevated Al, Fe,Cu levels

9 Impacts-Future-People Sediment Remobilization - Hard to Predict Sediment remobilization will occur Periodically. (high flows) Native American Communities Quote from Navajo Nation President Russell Begaye The Animas River and the San Juan rivers are our lifelines. Water is sacred to us

10 Impacts-Future-People-Environment Public Water Supplies Water quality is Regulated Farmers-Irrigation Districts Soils Irrigated with Contaminated Sediments Plant uptake: of some metals -Long Term? Wildlife Exposed to Contaminated Sediments Benthic Organisms Long Term? Fish - Long Term? Animals - Long Term?

11 Background I There are ~5,100+ Abandoned mines in CO, ~4,000 in NM, ~11,000 in UT, and ~24,000 in AZ (BLM) BLM, EPA, Forest Service + CO state and Local Agencies Collaborate The Upper Animas River has top priority for restoration 17 sites ? Cost >$5million? (BLM 2013) Lack of Funds limits Mine site evaluation, physical safety, restoration, closure efforts Reclaiming mine areas is difficult, expensive, often a long process

12 Background II Acid Mine Drainage is a Chronic issue in the Animas Upper Watershed Area An estimated 8.6 millions tons of mine tailings were discarded in or near these waterways (~ 120-year period) Rock weathering continues, specially during the wet-warm season From: USGS report. Water quality in the Upper Animas River. 2013

13 Chemistry Acid Forming Minerals: FeS 2, CuFeS 2, ZnS, PbS, (1S -> 8H + ) Acid Neutralizing Minerals are also Present CaCO 3, fast acting Weathering of Silicates,clays and other Minerals (slow, and requires lower ph) Chlorites, Albite, Hornblend, Sodic Feldspars.. (source: USGS Report )

14 Animas River Arriving at Silverton

15 Prevention Extreme Events like the Gold Mine Spill: Increase oversight (Regs) of ponds and mines that store slurries/acid leachates Limit Storage acid leachates in ponds and mines Better Onsite Treatment-Requirements? Allow Slow discharge? Increase funding for Closure/Removal of mines/acid mine tailings located on or near perennial streams

16 Mitigation Use Local Sources of Acid Neutralizing Minerals to: Isolate Waste Rock Heaps, mine tailings piles near waterways. Build Porous Barriers (shallow dams/pools) downstream from potential spill sites Issue: Animas River is a fast flowing recreational river with no dams

17 Conclusions Acid mine drainage will continue to impact the Upper Animas River given its long history of mining and hydro geologic conditions The Gold King mine accident has made us more aware of the fragility of these water resources and how important they are to downstream communities Studies are under way to determine the environmental and social impacts of this accident, in particular to Native American communities in the San Juan River More Funding is needed to: Better manage acid drainage and the closure on mining sites located in Upper Animas River Basin Develop novel strategies to reduce the impacts of acid mine drainage in the Animas River and protect downstream communities.

18 References Understanding the Gold King Mine Spill. Nov UA- Superfund Research Program. The Gold King Mine Spill: Can it Impact Water Users Below Lake Powell and Yuma Farmers? April UA- Extension Publication #AZ1698. Miscellaneous Geochemical Data from Waters in the Upper Animal River Watershed, CO US Geologic Survey Report Net Acid Production, Acid Neutralizing Capacity, and Geochemical Characteristics of Animas River Watershed Rocks near Silverton, CO US Geologic Survey Report

19 END Questions?