page 23-26 of the UWP Educator’s Guide to Teaching Students About the Upper Uncompahgre River Watershed (also see contents, introduction & pdf link)
Objectives:
- Students will use chemistry to simulate the creation of acid mine drainage.
- Students will recognize ideas for remediation, treatment and prevention.
Time Frame:
- Activity 50 minutes
- Reflection 15+ minutes to allow for conversations or writing about acid mine drainage history, policies, and potential solutions.
- Extension 30 mins: Use topographic maps to locate mines within the watershed
- Optional Extension: Research the nearby Gold King Mine Spill or Superfund sites and clean-up (see information and laminated photographs in the Education Trunk).
Teacher Background:
Acid rock drainage (ARD) occurs naturally when air and water enter the mountain through seeps and pores to interact with minerals (ie. pyrite), then exits the mountain as ARD. This has occurred in the San Juans since before mining started. Acid mine drainage (AMD) is formed by humans punching holes in the mountain, allowing air and water to interact with more pyrite. Human caused AMD certainly impacts our water significantly, but it is unknown to what extent each is responsible. Mining operations contributed to metals loading to alpine streams and creeks adding to the natural metal loading already occurring in the mineralized area. As a common practice, mine tailings were directly deposited into the creeks and rivers until the 1930’s. Water draining from the mines occurs when mining operations in the mountainsides alter the hydrology of the area and combine with natural springs, pulling water into mine tunnels. The water reacts with iron disulfide (pyrite) and oxygen to form sulfuric acid (acid rock/mine drainage). The resulting acidic water dissolves naturally occurring heavy metals such as zinc, lead, cadmium, copper and aluminum and results in water containing these metals flowing out of the mine adits (a horizontal shaft into a mine, which is used for access or drainage). By the end of mining operations, many of the mines were left discharging contaminated water into streams.
Materials
- Small beakers (1 per group of 2-4 students)
- Magnesium (small strips or bits)
- Water (can be tap water)
- 8 Clorox Pool pH strips w/ laminated color chart per group
- PPE: goggles/gloves for dealing with strong acids and bases
- HCl (or other strong acid) – Muriatic acid from hardware store works well
- NaOH (or other strong base) – Main Line Cleaner or Draino equivalent from hardware store. Make sure it is clear, not with coloring.
- Drawing of mountain with snow/rain infiltration through natural cracks and fissures, mine shafts and tunnels, and into the creek. This can be drawn on a white board as you discuss different components of the process.
References:
- Activity originated by Mountain Studies Institute of the San Juans
- Photo Images of the Gold King Mine Spill in the Animas River, from Durango Herald file
- Gold King Watershed Fact Sheet
- https://www.epa.gov/sites/default/files/2015-08/documents/goldkingminewatershedfactsheetbackground.pdf
- Superfund Sites Information: What is a Superfund? https://www.epa.gov/superfund/what-superfund
- Superfund Clean Up Process: https://www.epa.gov/superfund/superfund-cleanup-process
- Cleanups in my Community Interactive Map
- https://cimc.epa.gov/ords/cimc/f?p=CIMC:MAP:0::NO::P71_IDSEARCH:SF_SITE_ID|0802497
Activity Outline:
| Time | Activity |
| 5-10 | (OPTIONAL INTRO TO SUPERFUND) – What is Superfund and where are the sites? Superfund formed to clean up pollution that has been abandonedOptional: Reference the Gold King Mine Spill in the Animas River as an example of a polluted waterwayShow (interactive) map of EPA Superfund mine sites from their websiteCleanups in my Communityhttps://cimc.epa.gov/ords/cimc/f?p=CIMC:MAP:0::NO::P71_IDSEARCH:SF_SITE_ID|0802497 |
| 5 | Introduce Activity: We will follow a rain drop from cloud to river, exploring how it becomes polluted and cleaned up along the way.Safety rules (PPE) and instructions. GOGGLESNever inhale or touch. Refrain from touching eyes, mouth or nose.Wash hands after using chemicals. |
| 5 | Use a diagram of the mountainside (teacher created on the board) to discuss how water gets into and out of the mountain, contacting minerals along the way. |
| 5 | Complete steps 1- 3 on the datasheet, reminding students that we are simulating groundwater in the mountain running over metals. |
| 5-10 | Water becomes acidicUse the diagram of the mountain from earlier to introduce chemistry of [Air + Water + Minerals] -> [ACID]Depending on grade level, introduce the chemical formula (or not). |
| 5 | Complete steps 4-5 on the data sheetRemind students that we are simulating acidic water running through the mountain.Point out: now we have not only acid, but potentially toxic metals (some are OK, like Iron, and others are dangerous, such as Cadmium, Arsenic, Lead, Aluminum). |
| 5-10 | Brainstorm solutions:Prevention – we must really understand mountain hydrology to prevent water from becoming AMD.Bulkheads, diversions, brownfield capping and grading.Active remediation with chemistry: raise pH to extract metals. |
| 5 | Complete steps 6-7m of the datasheet |
| 5 | Wrap-upDiscuss impact/ expense of Active TreatmentDiscuss passive treatment as a sustainable, but not always feasible, optionPoint out the unsustainable nature of active remediation as it is. State of technology and the need for innovationPoint out the need for remediation, industry responsibility and the value of avoiding legacy environmental problems.De-brief question, activity, or game recommended, or use the questions on the bottom of the data sheet. Answers to question 2 would be that (1) our stomachs are already acidic (stomach acid) to digest food, but AMD and ARD to are strong to digest |
The 2-page Student Data Collection Sheet for Acid Drainage appears on the following page.
