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Download Chapter 3 - Land Use and Wellhead Protection
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WELLHEAD PROTECTION AND LAND USE “It’s Cheaper to Prevent Contamination” Common Naturally Occurring Problems in PA Groundwater • White residue, dull laundry – hardness – Especially in carbonate (limestone) areas • Reddish stains, metallic taste – iron – Common in sandstone / shale aquifers • Black stains, metallic taste - manganese – Often occurs with iron • Rotten egg odor - hydrogen sulfide gas – Very common in wells in certain shale formations • Blue stains, metallic taste - corrosive water – Generally caused by low pH and soft water Man’s Contamination of Groundwater Barnyard, yards, dumps, mines, septic systems, etc. Soil Bedrock Aquifer Aquifer Contamination Groundwater Moves! Well Head Contamination Surface water Water Supply Protection Starts at Home! Septic systems Driveways Fertilizer Pesticides Keep activities at least 100 feet or more from wellhead or spring box Wellhead Protection Area Zones for Public Water Supplies Where is the water that needs protection? Zone I 100 - 400 Ft Zone II Capture Zone Zone III Zone II + Zone III = Area of Contribution Red = sources of potential contamination Low Influence Moderate Influence High Influence An Example of Wellhead Protection Zones for A Well Wellhead Protection 100’ minimum Coliform Bacteria A Common Pollutant Entering Around Wellheads and Spring Boxes •“Indicator” organisms = indicate the “potential” for disease-causing bacteria (E. coli is an example) •One of the most common problems, occurs in ~50% of private wells and springs •Can enter wells and springs from surface runoff, human/animal waste, insects, etc. •May also occur from poor construction or aquifer contamination BACTERIAL CONTAMINATION TYPICALLY LOCALIZED, WELLHEAD ISSUE 33% exceed drinking water standard Seal the spring box to prevent insects, animals and surface contamination Don’t Get Carried Away ! Photo by Tom McCarty LAND USE IMPACTS GROUNDWATER Houses Landfills Organics, ? Bacteria Nitrate Sediment Yard Chemicals Roads Chloride, Sodium Mining Metals, pH Industry Organics, Petroleum Agriculture Bacteria, Nitrate, Pesticides Gas Drilling Barium, chloride, TDS How Close do Activities Need to Be? • In general, homeowners should be concerned about activities that are visible from their home • In limestone or gravel aquifers, activities further from the home could be important Example of Land Use Impact Nitrate-N in Water Wells 4% exceed drinking water standard Iron, Sulfate Are More Common Near Mining Percent Above Standard 50 40 30 Iron > 0.3 mg/L Sulfate > 250 mg/L 20 10 0 NW SW NC SC Region of PA NE SE Land Use Can Also Affect Water Quantity Impervious surfaces reduce groundwater recharge “Groundwater mining” may occur where more water is withdrawn than recharges Abandoned Water Wells May serve as a pathway for future contamination of groundwater Should be plugged by a licensed well driller Photo: Purdue Extension Service Graphic: North Dakota State Univ. Homeowner Actions • Practice local wellhead protection on their property • Be aware of current and proposed land use surrounding their property • Test water annually for pollutants associated with current or proposed land uses (legal protection)
