1. Contamination and other issues  Source Point sources Point sources Non-point sources Non-point sources Naturally occurring Naturally occurring  Reactions (chemical and biological)  Transport

2. Potential sources of contamination

3. Point sources Fuel storage tanks Landfill Septic tank Leaking tank in gas station Truck fuel spill Dry cleaner Factory wells, spills, emissions Households

4. Non-Point sources Naturally occurring Farm Brought by river Brought from outside area by groundwater

5. Cannot be traced to a specific spot Multiple sources Large area Source activities related either to land or water use Examples water runoff from urban areas construction sites agricultural failing septic tanks improper animal-keeping practices Improper forestry practices Non-Point source pollution

6. How Does Groundwater Contamination Move? Can be filtered if flows slowly, like through sands With groundwater down water table Not filtered if flows rapidly, like in limestone caves 17.10.a

7. http://techalive.mtu.edu/meec/module04/ContaminationMove ment.htm

8. LNAPL - Light Non-Aqueous Phase Liquids lighter than water generally petroleum NAPL - Non-Aqueous Phase Liquids http://toxics.usgs.go v/definitions/lnapls. html

9. DNAPL - Dense Non-Aqueous Phase Liquids denser than water chlorinated compounds PAHs http://water.usgs.gov/ogw/karst/k igconference/wj w_preliminaryco ncept.htm

10. (from USGS WRIR 02-4105)

11. Arsenic in groundwater  Depends on rock type (sulfide minerals)  Oxidation state  pH  Presence of Fe

12. Arsenic accumulation over time Tiles on cement block Increased coating on tiles with time http://portal.ncdenr.org/c/document_library/get_file?uuid=34d44ecd-33f1- 41a7-9cc7-164389e7de5e&groupId=38364

13. Bottom: Reducing Top: Oxidizing Arsenic accumulation 10 cm Reid, Haven, Eudy, Milosh, Stafford, 2007, Arsenic in Groundwater Investigations – Eastern Slate Belt (ESB): Nash and Halifax Counties, North Carolina

14. Source: DENR “North Carolina State of the Environment Report 2011” 2010 State-Wide Private Well Sampling Results NitratepHArsenicChromiumIronManganese State Groundwater Standard 10 mg/L 6.5- 8.5 10 ug/L 300 ug/L50 ug/L Number of samples 4,1104,9014,8704,8924,8964,900 Percent of samples exceeding standard 0.7%18.4% below pH of 6.5 2.4%1.5%57.6%39.9% NC population 10,000,000 ½ drink groundwater 2/4% of 5,000,000 people is 120,000 people

15. Arsenic Probability from Private Well Data (Pippin, 2005) Probability of a groundwater sample exceeding 0.001 mg/L 0.2 1 Pippin, 2005, Arsenic Occurrence in the Unconfined Fractured Bedrock Aquifer System of the North Carolina Piedmont

16. Arsenic Probability from Private Well Data (Pippin, 2005) Probability of a groundwater sample exceeding 0.001 mg/L 0.2 1 Carolina Slate Belt Kings Mountain Belt Charlotte Belt Inner Piedmont Belt Eastern Slate Belt

17. Probability of a groundwater sample exceeding 0.001 mg/L 0.2 1 USGS Estimated Use of Water in the US County-Level Data for 2010 Population using private wells

18. Take-aways  It’s easier to keep groundwater clean than to clean up contamination  Groundwater – Surface Water all one thing  Understanding the geology is critical to Public Health  Not all contamination is caused by humans  Well construction is different under certain geologic conditions

19. Take-aways Test your well! Learn what to test for – Depends on geology Depends on geology Land use practices Land use practices History of land use History of land use Contamination events Contamination events

20. Porosity and permeability - https://www.youtube.com/watch?v=zrewtz42Gmg https://www.youtube.com/watch?v=zrewtz42Gmg The space between the grains - https://www.youtube.com/watch?v=tt-mx25t7rA https://www.youtube.com/watch?v=tt-mx25t7rA “best extreme caving video” - https://www.youtube.com/watch?v=TucYTJe1WsA https://www.youtube.com/watch?v=TucYTJe1WsA Mammoth Cave, Kentucky - https://www.youtube.com/watch?v=fTNlZl7-s4w https://www.youtube.com/watch?v=fTNlZl7-s4w Geology of Mammoth Cave - https://www.youtube.com/watch?v=VFLDvzc5P2k https://www.youtube.com/watch?v=VFLDvzc5P2k Groundwater – good, but long - https://www.youtube.com/watch?v=ci-ABWPG7LQ https://www.youtube.com/watch?v=ci-ABWPG7LQ Wish we had this for eastern NC - https://www.youtube.com/watch?v=Z2HQY5A3o-s https://www.youtube.com/watch?v=Z2HQY5A3o-s

21. How Do We Depict the Water Table? Contour: water table at same elevation; blue arrows show flow Numbers show elevations of the water table: what is the pattern? Compare water table to other features 17.07.b

22.  Amy Keyworth amy.keyworth@ncdenr.gov 919-807-6460 NCDENR Division of Water Resources Division of Water Resources