Characteristics of Metals Concentrations in the Animas and San Juan Rivers During Passage of the Gold King Mine Release Plume

Transcription

1 Characteristics of Metals Concentrations in the Animas and San Juan Rivers During Passage of the Gold King Mine Release Plume Kate Sullivan, Mike Cyterski, Chris Knightes, John Washington, Steve Kraemer, Lourdes Prieto, Brian Avant Photo image area measures 2 H x 6.93 W and can be masked by a collage strip of one, two or three images. The photo image area is located 3.19 from left and 3.81 from top of page. Each image used in collage should be reduced or cropped to a maximum of 2 high, stroked with a 1.5 pt white frame and positioned edge-to-edge with accompanying images. Office of Research and Development National Exposure Research Laboratory June 2, 217

2 Setting for the Gold King Mine Release The Gold King Mine (GKM) is one of hundreds of abandoned mines in this area of SW Colorado GKM is among the top 8 candidates for remediation to reduce acid mine drainage in the headwaters of the Animas River according to the USGS study of the area During preliminary remediation work on August 5, 215, the closed mine entrance was accidentally breached An unexpectedly large volume of low ph, metalsladen water was released into Cement Creek

3 The mine is located about 14 km (~9 mi) from the confluence with the Animas River in Silverton The released volume was readily determined from the USGS gage in Cement Creek Approximately 3,, gallons (11.2 million liters) flowed out of the mine over a 7-hour period most in the first 4 hours This slug of water and metals was observed and measured for hundreds of kilometers downstream The flood of acidic water from the release was measured by the USGS gage in Cement Creek Streamflow (m 3 /s) /5 6: 8/5 8: 8/5 1: 8/5 12: Cement Creek Streamflow August 5-6, 215 8/5 14: 8/5 16: 8/5 18: Field Sample Cumulative million L (~3,, gal) from release 8/5 2: 8/5 22: 8/6 : 8/6 2: 8/6 4: 8/6 6: 8/6 8: 8/6 1: 8/6 12:

4 The Metals Mass Released from the Gold King Mine Total Metals Mass Estimated in GKM Effluent Mass (kg) at Release What was in the mine water? 25, 2, 15, 1, ~23, Manganese, 41 Aluminum, 375 5, ~2,9 Major Metals ~5 Trace Metals Mass of Major Metals in GKM Effluent at Release (kg) Zinc, 31 Copper, 8 Iron, 1,7 Other Metals In the mine, metals were almost exclusively dissolved in water with ph =2.9 18, kg sulfate 4,6 kg major cations (Ca, Mg, K, Na) Mass of Trace Metals in GKM Effluent at Release (kg).5 Mercury Silver Thallium Antimony Selenium Molybedenum Chromium Barium Beryllium Vanadium Arsenic Nickel Cadmium Lead Cobalt Mass (kg)

5 The real story of the release was the erosion of the waste pile outside the mine 12, metric tons A considerable mass of additional contaminated mine waste was entrained by the rushing water outside of the mine and in Cement Creek The entrained material was a mixture of particulate, sediment-bound, mineralized metals and inert country rock sediments

6 GKM Mass Delivered to the Animas River Concentration (mg/l) 5, 4, 3, 2, 1, Estimated Concentrations Total Metals in Cement Creek as GKM Plume Traveled from Gold King Mine to the Animas River Total Water Samples 8/5 12: 8/5 15: 8/5 18: 8/5 21: 8/6 : 8/6 3: 8/6 6: Estimated Mass Delivered to the Animas: 49, kg Colloidal/particulate: 475, kg Dissolved: 15, kg Major Metals (Pb, Cu, Zn, Cd, As) (11,6) Total Metals Mass Delivered to Animas River (kg) Major Cations (Ca, K, Mg, Na) 47,1 Other Trace Metals (9) Iron, Al, Mn (477,6) 1, Gold King Mine Release to Animas River Colloid/Particulate Dissolved Mass (kg) 5, Lead Manganese Zinc Copper

7 Path of GKM release and sampling Sampling For Metals Within the Animas and San Juan Rivers Number of 25 Total Water 2 Samples GKM Event FALL 215 SNOWMELT 216 FALL 216 Week Ending 31 sampling locations where one or more samples were collected EPA, states, tribes, NGO s Sampling began during GKM plume and continued at some locations through Fall 216 1,9 water and 99 sediment samples

8 The GKM plume traveled as coherent unit through the entire Animas and San Juan River system The plume was initially a highly acidic solution with high concentrations of particulate and dissolved metals The plume had a sharp front, highly concentrated inner core that passed quickly, followed by a low concentration tail that could be observed for days It traveled at an average speed of 3.2 km per hour (2 mph) and reached Lake Powell 55 km downstream in approximately 7 days Durango, CO Photo: Bruce Gordon EcoFlight Photo: Southern Ute Indian Tribe Aug 6 Aug 8 Aug13 Aug 18 Colorado Department of Public Health and Environment The concentrations of metals was constantly changing within the plume no two places saw exactly the same plume

9 To quantify the GKM plume, we combined empirical analysis of samples with a water quality model that simulated its movement through 55 km of river Concentration (mg/l) Method 1 Method 2 Water Analysis Simulation Program (WASP) Applies physical process modeling to hydraulics of flow, partitioning mass between the water and streambed Inflow Outflow Q in, water column Q out, Tot P,in C-Tot Tot P P settling resuspension burial surface sediment Q: flow into and out of each segment (m 3 /s) Tot P: Sum total of all particulate metals in the system (mg/l) 2-km segments Tot P,out Concentration (mg/l) Concentration (mg/l) 8/6 : Empirical Analysis of Observed Water Samples 8/6 3: 8/6 6: 8/6 9: 8/6 12: 8/6 15: Ideal Sample Coverage Fit a concentration trace to observed water concentration, interpolating between 8/6 18: 8/6 21: 8/7 : 8/7 3: 8/7 6: 8/7 9: Common Sample Coverage 8/7 12: 8/5 21: 8/6 : 8/6 3: 8/6 6: 8/6 9: 8/6 12: 8/6 15: 8/6 18: 8/6 21: 8/7 : 8/7 3: 8/7 6: 8/7 9: 8/7 12: 8/7 15: 8/7 18: 12 locations Concentration (mg/l) Analysis Goal: Replicate metal concentrations Compute mass load Quantify mass of material deposited Gold King Plume at Durango, CO (RK 95) nn CCCCCCCCCCCCCCCCCCCCCCCCCC mmgg QQ(lliiiiiiiiii) xx = LLoooooo (kkgg) 25 LL 1,, Sample WASP 16.6 Empirical Model Water Volume During Interval /6 6: 8/6 18: 8/7 6: 8/7 18: 8/8 6: --Flow obtained from nearest USGS gages --Concentrations estimated in 12- to 15-minute intervals Streamflow (Liters x 1 6 )

10 Dilution, deposition, and chemical reactions caused concentrations of dissolved and colloidal/particulate metals to decrease as the GKM plume traveled Samples near plume peak Only 6 samples timed at or close to peak Almost all metals of interest follow this pattern Empirically modeled plume and water samples Summed Total Metals, Minus Major Cations - Animas River Total Concentration (mg/l) 1,. RK 12.5, 39,683 RK 12.5 RK 16.4 RK 63.8 RK ,. RK RK RK 16.4, 11,583 RK 19.2 Observed 1,. RK 63.8, 521 RK 94.2, RK 131.5, 13.1 Observed Aug 5-Aug 11, RK 164.1, 62.1 RK 19.2, /5 8/6 8/7 8/8 8/9 8/1 8/11 Date Modeled Peak Concentrations 1 Empirical Peak Conc Total Lead 1 Empirical Peak Conc Diss 1 WASP Peak Conc Total 1 WASP Peak Conc Diss River Distance (km) Peak summed water concentrations declined more than 3 orders of magnitude as the GKM plume flowed through the Animas River Concentration (mg/l)

11 ph Saturation Index ph at Peak of Gold King Plume SUIT NMED Estimated Cement Creek Estimated Upper Animas Distance from GKM Sourcre Distance to Neutralize Acidity Indicated by Saturation with Calcite Distance (km) Concentrations and mass of metals were affected by various processes as the GKM plume moved: Neutralization of Acidity Calcite SI Iron and Aluminum (hydr)oxides and other incipient minerals formed Yellow color intensified as neutralization proceeded indicative of Fe and Al (hydr)oxides 15, kg of dissolved major and trace metals precipitated into minerals Cumulative Sorbed Mass (kg) 2, 15, 1, 5, Photo: Mor,cCC BY NC 2. Sorption of Dissolved Metals Dissolved Load, Summed Metals at Cement Creek = 15, Distance From GKM (km)

12 Deposition Materials sourced from: Contaminated soils outside Gold King Mine and hillslope between mine and Cement Creek Scoured from Cement Creek Aggregated colloidal matter created from dissolved metals in the mine effluent Partitioning- a function of ph, metal species, time Dissolved Dispersed and aggregated colloids Colloids are fine solid particles suspended in a liquid, e.g. milk or paint Sediment in transport a mixture: Larger particulates (sand/silt) Fine particulates (clay) Aggregated colloidal precipitates of varying size, texture, and stability Sludge-like Settled aggregated precipitates In the streambed metals: bind to surfaces of rocks, sand grains, and clay become entrapped by microbes may will mineralize be biologically eventually taken up or released

13 Concentrations and mass of metals were affected by various processes as the GKM plume moved: Dilution As the GKM plume traveled, the release volume was mixed into the waters of the Animas and San Juan Rivers that contained much lower concentrations of metals. Flow increased from 122 cfs in the Animas above Cement Creek to 2,86 cfs in the San Juan at Bluff, Utah Significant dilution of the release mixture occurred by the time the plume passed Silverton Concentration Relative to Source (%) Dilution of Concentration Due to Water Inflow Relative To Source Cement (RK 12.5) 1 % Below Silverton (RK 16.4) 12.9% USGS above Tacoma (RK 48.8) 2.7% Durango (RK 95.1).5% USGS near Cedar Hill (RK 129.6) USGS below Aztec (RK 167.4).19% Animas at Farmington (RK 189.6).15% Distance from Source (km)

14 Most of the metals mass released from GKM moved in a highly concentrated core with a duration of about 12 hours Continuously measuring sondes helped establish internal characteristics of the plume 55 Specific Conductance -- Animas River at AR 19-3 (RK 14) µs/cm /7/15 5:3, Specific Conductance Monitored by Sondes in the Lower Animas River RK 14.2 RK 19. RK RK RK / /5 8/6 8/7 8/8 8/9 8/1 8/11 8/12 8/13 8/14 8/15 8/16 8/17 8/18 ph in the Animas River at AR 19-3 (RK 14) 8/19 Specific Conductance (µs/cm) /6 8/7 8/7 8/8 8/8 8/9 8/9 8/1 8/1 ph /4 8/5 8/6 8/7 8/8 8/7/15 6:, /9 8/1 8/11 8/12 8/13 8/14 8/15 8/16 8/17 8/18 8/19 Sonde parameters showed that the GKM plume traveled in a very tight profile The plume maintained a remarkably consistent shape over a long distance with very little dispersion of the core

15 Internal characteristics of the Gold King Plume Individual sonde parameters systematically peaked at different times Sonde Plume Shape Factor minutes + 3 to 6 minutes Implied there was a series of fronts of dissolved ions, lower ph at core, trailed by colloidal/particulates AR19.3 (RK 14.) Specific Conductance Normalized to Peak AR16 (RK 19.) NAR 6 (RK 131.5) 66Ani28.1 (RK 164.1) 66Ani1.7 (RK 189.4) Observed Metal Concentration Hours Since Arrival of Plume Shape Factor: Normalized to Peak Metals concentrations followed the specific conductance shape closely Concentration (mg/l) /6 6: 8/6 12: Animas River at Durango (RK 94.2) Summed Metals Sample WASP Model Empirical Model Normalized Shape Factor 8/6 18: 8/7 : 8/7 6: 8/7 12: 8/7 18: 8/8 : 8/8 6: 8/8 12: 8/8 18: 8/9 : Normalized Sonde Factor

16 The Gold King Mine plume as it entered the San Juan River The San Juan River had high sediment loads during passage of the GKM plume Sediment provides another source of metals During GKM Plume Animas River Confluence of Animas and San Juan as GKM plume passed through (RK 191) At the same time, concentrations in the plume were relatively low Strong visual and measured signal lost due to sediment associated metals The San Juan doubled the flow and further diluted the plume Total Suspended Solids Concentration (mg/l) 1, 1, 1 Suspended Solids in the San Juan River Animas River San Juan River Distance from GKM (km) Observed Aug 9, 215 San Juan River in Utah during the GKM plume

17 Comparison of concentrations in the Animas and San Juan Rivers at the GKM plume peak shows metals more comparable Total Concentration (µg/l) 6, 5, 4, 3, 2, 1, GKM Peak in Farmington Animas River San Juan River Aluminum Iron Total Concentration (µg/l) 1, GKM Peak in Farmington Animas River San Juan River Copper Lead Zinc Barium Manganese Total Concentration (µg/l) GKM Peak in Farmington Animas River San Juan River Arsenic Nickel Vanadium The combination of relatively low concentration of metals in the GKM plume at this point and the additional metals from the San Juan sediments made it much more challenging to isolate and quantify the plume. No dissolved metals from the GKM release were delivered to the San Juan Sediment naturally contains metals Some metals were higher in the Animas than the San Juan during the plume Lead, Copper, Iron, Arsenic Some were higher in the San Juan Aluminum, Barium, Manganese

18 Metal Concentrations in San Juan River During GKM Plume at RK 196 in Farmington Turbidity (NTU) 2, 1,5 1, Continuous sonde at RK 24 shows GKM in relation to background sediment 5 San Juan River at Farmington (Sonde 67SanJuan88.1, RK 24.4z Turbidity Sonde Shape Factor 8/7 18: 8/7 21: 8/8 : 8/8 3: 8/8 6: 8/8 9: 8/8 12: 8/8 15: 8/8 18: 8/8 21: 8/9 : 8/9 3: 8/9 6: 8/9 9: 8/9 12: 8/9 15: 8/9 18: 8/9 21: 8/1 : 8/1 3: Sonde Shape Factor Concentration (µg/l) /8 : 4, Total Lead in San Juan River at RK /8 5: 8/8 1: 8/8 15: 8/8 2: Lead 8/9 1: Metals Concentrations 8/9 6: 8/9 11: Concentration (µg/l) /8 : 2 Total Arsenic in San Juan River at RK /8 6:48 8/8 13:35 Arsenic 8/8 2:23 8/9 3:11 8/9 9:59 ph /8 6: Expected Arrival of Peak 13:45 8/8 8: 8/8 1: 8/8 12: 8/8 14: 8/8 16: 8/8 18: 8/8 2: ph 8/8 22: Sonde Shape Factor Concentration (µg/l) 3, 2, 1, 8/8 : 8/8 5: 8/8 1: 8/8 15: Aluminum 8/8 2: 8/9 1: 8/9 6: 8/9 11: Concentration (µg/l) /8 : 8/8 5: 8/8 1: 8/8 15: Chromium Note: we combined measurements at two sites accounting for travel time to produce these graphs 8/8 2: 8/9 1: 8/9 6: 8/9 11: Metals were elevated within the background during a 4 to 12 hour period at the expected arrival time of the GKM plume

19 GKM peak concentrations in the San Juan River Total Metals Due to GKM at Plume Peak Total concentrations of metals due to GKM at peak generally remained constant or declined through the San Juan The Aluminum and lead levels exceeded some Navajo Nation and Ute Mountain Ute water quality criteria for domestic water use and agriculture Concentration (mg/l) Animas at Farmington (RK 19) San Juan at Farmington (RK 196) Shiprock (RK 246) Four Corners (RK 296) Iron Aluminum Bluff (RK 377) Mexican Hat (RK 421) Total Metals Due to GKM at Plume Peak Total Metals Due to GKM Plume at Peak Concentration (mg/l) Animas at Farmington (RK 19) San Juan at Farmington (RK 196) Shiprock (RK 246) Four Corners (RK 296) Bluff (RK 377) Lead Zinc Copper Mexican Hat (RK 421) Concentration (mg/l) Animas at Farmington (RK 19) San Juan at Farmington (RK 196) Shiprock (RK 246) Arsenic Cadmium Cobalt Chromium Four Corners (RK 296) Bluff (RK 377) Mexican Hat (RK 421)

20 Gold King Mine Cement Creek ( RK 12.5) Silverton (RK 16.4) Baker's Bridge (RK 63.8) Durango (RK 94.2) NAR6 (RK 131.5) Aztec (RK 164.1) Farmington (RK 19.2) Farmington (RK 196.1) Shiprock (RK 246.4) Four Corners (RK 295.8) Bluff (RK 377.6) Mexican Hat (RK 421.3) 2,872 79,52 72,828 54,657 52,97 41,636 39,994 26,396 25,784 23,757 GKM Plume Mass Accounting 155,396 Mass Transport During the GKM Release Plume (kg) Mass (kg) 2, 4, 6, 1 excludes major cations 49,44 457,124 Summed Metals minus major cations Gold King Mine Cement Creek ( RK 12.5) Silverton (RK 16.4) Baker's Bridge (RK Durango (RK 94.2) NAR6 (RK 131.5) Aztec (RK 164.1) Farmington (RK 19.2) Farmington (RK 196.1) Shiprock (RK 246.4) Four Corners (RK 295.8) Bluff (RK 377.6) Mexican Hat (RK 421.3) ,241 Mass (kg) 2, 4, 6, 8, 1, Lead 7,658 7,625 The GKM plume delivered about 24, (up to 45,) kg of metals to Lake Powell. The remaining 465, kg were deposited in the Animas and San Juan Rivers. Gold King Mine Cement Creek ( RK 12.5) Silverton (RK 16.4) Baker's Bridge (RK 63.8) Durango (RK 94.2) NAR6 (RK 131.5) Aztec (RK 164.1) Farmington (RK 19.2) Farmington (RK 196.1) Shiprock (RK 246.4) Four Corners (RK 295.8) Bluff (RK 377.6) Mexican Hat (RK 421.3) Mass (kg) Arsenic

21 Summary of Gold King Mine Plume The Gold King release was initially a highly concentrated mass of particulate/colloidal and dissolved that migrated through the system as a concentrated plume of material Most of the material came from the waste pile outside the mine not from within it. The most noteworthy contaminants were lead, and to a lesser extent, arsenic Various physical and chemical processes worked on the release plume reducing its acidity, and transforming the dissolved fraction to solids while incorporating them into minerals such as iron and aluminum (hydr)oxides The concentrations of metals declined significantly as the plume moved due to dilution and deposition 9% of these solids deposited before the GKM plume reached Lake Powell, with 8% left in the Animas River upstream of Durango Lead and aluminum criteria for agricultural and domestic water use were exceeded in some locations during passage of all or part of the plume.