1. A NALYSIS AND SIMULATION OF REACTIVE TRANSPORT OF METAL CONTAMINANTS IN GROUND WATER IN THE P INAL C REEK B ASIN, A RIZONA Dan Portlock Environmental Engineering NDSU Geol 628 Geochemistry 12/1/10

2. Introduction Background information on Pinal Creek mining Background information on Advection and Transport Modeling Advection and Transport Modeling using Phreeqc Compare current and present modeling Conclusion

3. I NTRODUCTION Large scale mining activities generated a plume of acidic ground water more than 15 km long in the aquifer of the Pinal Creek Basin In 1984, the acidic part of the plume had a pH as low as 3.4 and contained milligram-per- liter concentrations of iron, copper, aluminum and other metals. Contaminant sources include mine tailings, heap-leach areas, surface impoundments of water associated with mining processes and occasional spills of contaminated water into streambeds.

4. P INAL C REEK W ELLS

5. P INAL C REEK F LOW D IAGRAM

6. P INAL C REEK W ELLS ConstituentWells 51101202302402451503702PCID Sample date 11-84 3-8511-84 3-897-865-901-93 pH 3.623.649.193.544.104.946.157.007.7 Calcium 12.211.51.216.713.014.715.213.81.4 Magnesium 16.012.30.3711.95.765.475.765.060.31 Sodium 10.08.260.966.963.483.593.393.030.33 Potassium 0.240.250.0360.210.190.280.110.160.087 Alkalinity ——————2.053.520.93 TIC 4.004.42—4.914.084.67——— Sulfate 10473.90.771.827.124.820.818.221.46 Chloride 11.010.40.488.743.955.133.662.340.107 Fluoride 2.11.40.0021.40.350.530.0210.0130.02 Silica 1.661.650.361.831.451.141.010.458— Iron 57.339.40.0007332.26.272.470.00320.0190.00013 Manganese 1.331.04< 0.000561.090.911.890.8190.0520.00098 Aluminum 11.18.54< 0.0036.690.4090.1530.00070.186— Cadmium 0.00350.0018< 0.000450.0020.00040.00010.000040.000030.000009 Copper 2.361.890.000161.530.300.1770.0005< 0.0020.00047 Cobalt 0.180.14< 0.000340.120.0300.031< 0.00020< 0.003— Nickel 0.0650.054< 0.00850.0510.0190.0200.007< 0.008— Strontium 0.0170.0180.00230.0340.0200.0180.2400.027— Zinc 0.290.18< 0.000230.140.0460.530.00290.002< 0.00005 Table 1 Measured water chemistry of wells along simulated flow path, Pinal Creek Basin, 1984–1990 Values are in mmol/l except for pH. Dashes indicate no data; PCID, Pinal Creek at Inspiration Dam; TIC, total inorganic carbon.

7. A DVECTION (http://wwwbrr.cr.usgs.gov/projects/GWC_coupled/phreeqc)http://wwwbrr.cr.usgs.gov/projects/GWC_coupled/phreeqc

8. A DVECTION M ODEL Number of cells or sample points Solutions that needs to be output

9. T RANSPORT ( ADVECTION AND DISPERSION ) Distance between sample points Dispersivity between sample points Number of shifts (pore volumes) Time step Boundary conditions Direction of flow

10. A DVECTION ( ONE PORE VOLUME )

11. T RANSPORT (O NE P ORE V OLUME )

12. T WO P ORE V OLUMES

13. T HREE P ORE V OLUMES

14. T RANSPORT AND A DVECTION P H

15. C OMPARED M ODELING R ESULTS

16. C ONCLUSIONS The advection model is a quick and simple method for analyzing the transport of metals or other contaminants in a system -It does not account for the distance traveled or the reaction that occurs which could lead to problems when analyzing a more complex system. The transport model includes dispersion and reaction time which will provide a more detailed analysis of a system. -The parameters in the transport model are sometimes hard to estimate which could lead to errors.

17. R EFERENCES Brown, James., Analysis and simulation of reactive transport of metal contaminants in ground water in Pinal Creek Basin, Arizona 1997. Journal of Hydrology 209, 225- 250. Brown, J.G., Eychaner, J.H., 1996. Research of acidic contamination of ground water and surface water, Pinal Creek Basin, Arizona. In: J.G. Brown and B.O. Favor, (Editors), Hydrology and geochemistry of aquifer and stream contamination related to acidic water in Pinal Creek Basin near Globe, Arizona. US Geological Survey Water-Supply Paper 2466, pp. 1–20.

18. Q UESTIONS Thank you