Texas Association of Groundwater            Districts  Anthropogenic GroundwaterContamination in Texas Aquifers           ...
Background• TWDB-sponsored project• Sister project with “Natural Sources of  Groundwater Contamination in Texas”  performe...
Objectives• Mapping and analysis intended for use by  RWPGs: Drinking Water-centric• Potential sources of groundwater  con...
Sources of Data• TCEQ    –   SWAP Database – Potential Sources of Contamination (PSOCs)    –   http://gis3.tceq.state.tx.u...
Groundwater Quality Data• Chemical Analytical Data  – Public Water Supply (PWS) wells and Irrigation Wells    from Interag...
Data and Mapping Issues• Scale, data availability, quality, variability
Contamination Mechanisms
Contamination Mechanisms
PWS Wells• 12,636 Operational PWS wells in TX• 5,961 PWS Systems• WQ Data from 1,292  – Pre-Treatment or mixing; represent...
Potential Sources of Contamination               (PSOCs)• Business  – Gas Stations, Automotive businesses, dry cleaners, e...
PSOCs – Some Statistics• Business   – 55,409 Petroleum Storage Tanks   – 29,987 Automotive Businesses• Industry   – 473,81...
Sample MapChemical Pipelines, Regions H, I, and D
Sample MapActive O&G Wells, Regions E, F, and J
Sample MapInactive O&G Wells, Regions E, F, and J
Sample MapInactive O&G Wells, Regions D, H, and I
Sample MapCAFOs, Regions A, and O
Sample MapSuperfund Sites in State
Common Anthropogenic Contaminants• Hydrocarbons   – BTEX, MTBE      • Lighter than water      • Readily metabolized by nat...
TCEQ Groundwater Contamination Cases
Contamination Cases Requiring Public Notification of Private Well Owners                     Number of Sites              ...
Impacted Groundwater Summary               Atrazine – Most commonly detected compound                 PCE – Most commonly ...
Sample Map WQ Results – Atrazine in Groundwater
Sample Map WQ Results – PCE in Groundwater
Sample Map WQ Results – Nitrates in Groundwater
WQ Results – No apparent increasing         trends with time
Volume Calculations    Part 1, Area
Volume Calculations                             Part 2, Depth H = (0.0112*L2)0.5 + b{1-exp[(-L*I)/(K*i*b)]}WhereH = mixing...
Volume Calculations             Conservative Assumptions• A single lab result that  exceeds PCL will tag that  location wi...
Calculated Volume of Affected Groundwater     Total Calculated Volume = 1.65 Million Acre-feet                            ...
VOC Treatment CostsDependent on influent concentration and treatment volume•   60 gpm: ~ $2-4/1,000 gallons•   650 gpm: ~ ...
Comparison with Other Studies - VOCs                                                    Data Source     Parameter         ...
Comparison with Other Studies -               Pesticides                                            Data Source    Paramet...
PDF Map and Plates Linkhttp://www.twdb.state.tx.us/publications/reports/contracted_reports/index.asp
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Dave O'Rourke, Anthropogenic Groundwater Contamination in Texas Aquifers

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Dave O'Rourke, Anthropogenic Groundwater Contamination in Texas Aquifers

  1. 1. Texas Association of Groundwater Districts Anthropogenic GroundwaterContamination in Texas Aquifers November 30, 2011 Dave O’Rourke, PG, PE LBG-GUYTON ASSOCIATES
  2. 2. Background• TWDB-sponsored project• Sister project with “Natural Sources of Groundwater Contamination in Texas” performed by BEG• Project completed in August 2011
  3. 3. Objectives• Mapping and analysis intended for use by RWPGs: Drinking Water-centric• Potential sources of groundwater contamination from human activity• Published chemical analytical data for common anthropogenic contaminants• Volume and treatment cost estimates of affected water
  4. 4. Sources of Data• TCEQ – SWAP Database – Potential Sources of Contamination (PSOCs) – http://gis3.tceq.state.tx.us/swav/Controller/index.jsp?wtrsrc= – PWS chemistry data – Interagency Pesticide Database• EPA - Underground Injection Control Database• TWDB - Groundwater Database• Railroad Commission• USGS – NAWQA – NWIS• Edwards Aquifer Authority• Does NOT include contaminant monitoring wells
  5. 5. Groundwater Quality Data• Chemical Analytical Data – Public Water Supply (PWS) wells and Irrigation Wells from Interagency Pesticide Database – Pre-Treatment or mixing; representative of source groundwater – Non-standard data. Various data sources, sampling periods, detection limits, etc. – Challenges for volume estimates
  6. 6. Data and Mapping Issues• Scale, data availability, quality, variability
  7. 7. Contamination Mechanisms
  8. 8. Contamination Mechanisms
  9. 9. PWS Wells• 12,636 Operational PWS wells in TX• 5,961 PWS Systems• WQ Data from 1,292 – Pre-Treatment or mixing; representative of source groundwater – Non-standard data - Various data sources, sampling periods, detection limits, etc.
  10. 10. Potential Sources of Contamination (PSOCs)• Business – Gas Stations, Automotive businesses, dry cleaners, etc.• Industry – Chemical manufacturing, natural resource production, pipelines, etc.• Waste Disposal – Landfills, Injection Wells, Wastewater facilities, etc.• Agriculture – Irrigated lands, CAFOs
  11. 11. PSOCs – Some Statistics• Business – 55,409 Petroleum Storage Tanks – 29,987 Automotive Businesses• Industry – 473,818 Active Oil/Gas Wells – 619,637 Inactive/Abandoned Oil/Gas Wells – 187,000 miles of chemical pipeline• Waste Disposal – 429 Class I UICs – 39,452 Class II UICs – 2,520 Abandoned MSW Landfills – 1,862 Active MSW Landfills
  12. 12. Sample MapChemical Pipelines, Regions H, I, and D
  13. 13. Sample MapActive O&G Wells, Regions E, F, and J
  14. 14. Sample MapInactive O&G Wells, Regions E, F, and J
  15. 15. Sample MapInactive O&G Wells, Regions D, H, and I
  16. 16. Sample MapCAFOs, Regions A, and O
  17. 17. Sample MapSuperfund Sites in State
  18. 18. Common Anthropogenic Contaminants• Hydrocarbons – BTEX, MTBE • Lighter than water • Readily metabolized by native bacteria• Chlorinated Compounds – PCE, TCE, Disinfection By-products (DBPs) – Heavier than water, not as easily metabolized• Pesticides/Herbicides – Atrazine, Diuron• Nutrients – Nitrates
  19. 19. TCEQ Groundwater Contamination Cases
  20. 20. Contamination Cases Requiring Public Notification of Private Well Owners Number of Sites Number of Year Requiring Notifications Notifications 2004 24 9,695 2005 10 183 2006 31 423 2007 38 843 2008 42 610 2009 39 419 2010 23 476 Source: TGPC, 2009. 2010 (Draft)
  21. 21. Impacted Groundwater Summary Atrazine – Most commonly detected compound PCE – Most commonly detected above PCL PCL (ug/L) % Wells with % Wells > % Analyses with % of Analyses > MCL Positive PCL Positive Detection Detection Atrazine 3 20.20% 0.45% 27.99% 0.55%Chloroform 80 13.33% 0.04% 15.92% 0.02% PCE 5 3.70% 1.37% 15.11% 1.70% Simazine 4 8.18% 0.00% 14.64% 0.00% Prometon 400 4.68% 0.00% 10.63% 0.00% Diazinon 1 4.26% 0.06% 3.17% 0.04% TCE 5 5.06% 0.44% 3.69% 0.25% 1,1,1-TCA 200 1.88% 0.00% 1.50% 0.00% 2,4-D 70 3.00% 0.07% 2.25% 0.05% MTBE 13 2.15% 0.25% 1.80% 0.25%Metolachlor 700 4.60% 0.00% 1.30% 0.00% Benzene 5 1.76% 0.20% 1.78% 0.23%Tebuthiuron 1000 5.31% 0.00% 1.20% 0.00% Carbaryl 40 1.15% 0.00% 1.25% 0.00% Alachlor 2 0.58% 0.00% 0.40% 0.00% cis-1,2 DCE 70 0.48% 0.05% 0.45% 0.07% Diuron 2 1.13% 0.28% 0.99% 0.25% Maximum 20.20% 1.37% 27.99% 1.70%
  22. 22. Sample Map WQ Results – Atrazine in Groundwater
  23. 23. Sample Map WQ Results – PCE in Groundwater
  24. 24. Sample Map WQ Results – Nitrates in Groundwater
  25. 25. WQ Results – No apparent increasing trends with time
  26. 26. Volume Calculations Part 1, Area
  27. 27. Volume Calculations Part 2, Depth H = (0.0112*L2)0.5 + b{1-exp[(-L*I)/(K*i*b)]}WhereH = mixing zone depth (ft)L = Source length parallel to flow direction (ft)I = Infiltration rate (ft/yr)K = Aquifer hydraulicconductivity (ft/yr)i = Hydraulic gradient (ft/ft)b = Aquifer thickness (ft)
  28. 28. Volume Calculations Conservative Assumptions• A single lab result that exceeds PCL will tag that location with excedence even if subsequent sampling indicates reduced concentrations• Lateral areas of contamination likely overestimated due to sparsity of data points• Vertical mixing depth likely overestimated, often full aquifer thickness
  29. 29. Calculated Volume of Affected Groundwater Total Calculated Volume = 1.65 Million Acre-feet 16% of annual pumpage Annual TX GW Pumpage ~ 10 million ac-ft 1.6% of 10 years pumpage This estimate is likely quite conservative. A more reasonable estimate may be indicated by the percentage of analyses exceeding PCL, in the 1% range of annual pumpage.
  30. 30. VOC Treatment CostsDependent on influent concentration and treatment volume• 60 gpm: ~ $2-4/1,000 gallons• 650 gpm: ~ less than $1/1,000 gallons
  31. 31. Comparison with Other Studies - VOCs Data Source Parameter Current Study EAA Study 1 USGS Study 2 Volatile Organic Compounds Benzene 1.3% 0.7% 2.1% Toluene 5.5% 3.8% 0.0% Ethylbenzene 0.6% 1.2% 0.6% Total Xylenes 1.0% 0.6% 1.7% MTBE 1.9% 0.7% 12.7% PCE 18.7% 22.2% 19.5% TCE 4.5% 6.2% 14.0% 1,1,1-Trichloroethane 1.8% 1.2% 9.5%cis-1,2-Dichloroethene 0.6% 0.5% 9.5% Vinyl Chloride 0.3% 0.4% 0.9% Carbon Tetrachloride 0.2% 0.4% 1.4% Chloroform 18.1% 18.9% 36.1%
  32. 32. Comparison with Other Studies - Pesticides Data Source Parameter Current Study EAA Study 1 USGS Study 2 Pesticides and Herbicides Atrazine 55.6% 25.8% 29.9% Simazine 17.3% 15.5% 16.7% Prometon 13.3% 17.4% 11.3% Deethylatrazine 39.7% 63.5% 34.4%Deisopropylatrazine 14.8% No data 13.0% Diazinon 3.6% 2.8% 0.0% 2,4-D 2.6% 2.7% 0.5% Carbaryl 1.5% 1.0% 0.5% Metolachlor 1.7% 1.6% 10.9% Tebuthiuron 1.5% 0.5% 0.9% Diuron 1.2% 1.1% 3.3% Dieldrin 0.1% 0.3% 0.5% Alachlor 0.6% 0.0% 1.4% Dinoseb 0.0% 0.0% 0.9% Acetochlor 0.0% 0.0% 0.5%
  33. 33. PDF Map and Plates Linkhttp://www.twdb.state.tx.us/publications/reports/contracted_reports/index.asp
  34. 34. Questions ?

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