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Class IV Underground Injection Wells

Class IV underground injection wells have been determined to be a significant threat to human health and the environment by the US EPA and as such have been banned for use. These were wells where dangerous waste had been introduced either into or above the drinking water strata. They are still being used where it is necessary to clean up existing contamination, but new wells constructed and operated for the purpose of disposal of hazardous waste are prohibited.

Best Practices for Class IV Underground Injection Wells

  • • Class IV injection wells that are part of an official cleanup need to be approved by the US EPA or the state.
  • • Use where appropriate in situ bioremediation of groundwater techniques. See information below concerning how these techniques work and their effectiveness.

Class V Underground Injection Wells

Class V underground injection wells have been utilized in various areas of the country, especially where public wastewater treatment has not existed. These wells may range from cesspools to complex injection wells. There may be as many as 1.5 million Class V wells in the United States, some of which are of little consequence and others which can cause serious potential problems depending on the well construction, the local geology, closeness to local water supplies, and the types of waste fluids being injected. Some of the worst shallow injection wells are those used for motor vehicle waste disposal, large size cesspools for multiple dwellings or a business, and stormwater drainage wells. Currently, new large capacity cesspools and new motor vehicle waste disposal wells have been banned by the US EPA. The old ones have to be closed down appropriately in some states and in other states the automobile business can get a permit providing the waste is not contaminating the groundwater supply. (See endnote 62.) For the large capacity cesspool, the individual cannot contaminate the groundwater supply if the state allows a special permit for the cesspool use. (See endnote 63.)

Federal funding for the Underground Injection Control program has been diminished and as a result less attention is being focused on this serious means of contaminating the groundwater supply. Much of the program is carried out by certain states and they are given federal mandates to do things without much funding, which is approximately $11 million yearly for the entire country, to carry out the necessary functions.

There are 32 different types of Class V injection wells in seven different categories. The categories are:

  • 1. Drainage wells which can range from agricultural drainage to stormwater drainage to industrial drainage or other special purposes. Risk for people and the environment varies from low to high, with the high level relating to pesticides, nutrients, pathogens, and heavy metals.
  • 2. Geothermal reinjection wells of several types which have potential moderate hazards from pH problems, hot geothermal problems, and the materials within the solution.
  • 3. Domestic wastewater disposal wells which range from untreated sewage to septic systems to the effluent of public wastewater treatment plants which has gone through secondary or tertiary treatment. Risk ranges from low to high depending on the amount of raw sewage and treatment.
  • 4. Mineral and fuel recovery wells used for mining, fuel recovery, cleaning of air scrubbers, and water softener regeneration. Hazards rank from low to moderately high depending on the chemicals that are present in the fluid and whether or not the water is acidic.
  • 5. Industrial, commercial, and utility waste wells. Hazards rank from low to high depending on the amount of heat, suspended solids, heavy metals, solvents, and cleaning agents.
  • 6. Recharge wells which are used for recharging an aquifer by injecting fresh water to keep salt water intrusion from occurring and controlling settling of the ground. Aquifer storage and recovery wells are used to store water underground for some use in the future. Hazards rank from low to high depending on the quality of water used on the recharging of the aquifer.
  • 7. Miscellaneous wells which include those for experimenting on unproven technologies and for remediation of aquifers, abandoned drinking water wells now used for sewage disposal, and any other unspecified Class V wells. The hazards rank from low to high depending on the nutrients which are being introduced as well as levels of chemicals and microorganisms.

Best Practices for Class V Underground Injection Wells (See endnote 66)

  • • Do not discharge any wastewater into stormwater infiltration systems.
  • • Remove sediment from stormwater prior to the injection well. The sediment may clog the infiltration system and include metals, oil and grease, pesticides, phosphorus, and other contaminants.
  • • Separate potential contaminants from stormwater by using curbing, containment dikes, or covering materials to prevent leaching of the waste material or raw or finished products from rain which would cause contaminated runoff.
  • • Fuel vehicles and equipment in areas where a spill or overfill will not be washed into runoff areas from heavy rains. Conduct routine and required maintenance of these vehicles and equipment in these areas.
  • • Wash all equipment and vehicles in areas where the wash water is self-contained and then treated before release.
  • • Do not discharge any wastewater directly into the groundwater or below the highest seasonal groundwater table.
  • • Use spill control procedures to prevent wastewater from going into the groundwater.
  • • Separate all Class V wells from water supplies, wetlands, surface or subsurface drains, etc.
  • • The minimum depth between the Class V well measured from the base of the filter sand and stone beneath it to the seasonal high groundwater table is 2 feet for all stormwater wells, 4 feet for other types of Class V wells, and where percolation rates are 2 minutes or less per inch then the well should not be used at all because of potential contamination of the groundwater.
  • • The minimum distance between the base of the Class V well and bedrock should be 5 feet.
  • • All closures of these wells must be done in accordance with the regulations of the authorizing authority.
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