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Subsurface Integrity

Ensure Subsurface Integrity & Eliminate Sources of Ground & Surface Water Contamination

  • Properly plug all drill holes and other subsurface openings (mine shafts, adits etc.).
  • Stabilize, properly back fill, cap, and/or restrict from entry all open shafts, underground workings, and other openings.
  • Control sources of contamination and implement best management practices to protect surface and
    groundwater quality.
  • Erosion Control
    • Placement away from Surface Water resources including but not limited to drainages, domestic and stock wells,
    • Using the lowest quality water necessary for the project to diminish unnecessary use of high quality water
    • Cement to surface water wells used for industrial processes instead of bentonite
    • Use longer well conductors and cement in place
    • Closed loop and semi closed loop drilling systems
    • Minimize the surface footprint of the project to the extent practical
    • Stabilize surface disturbance
    • Accelerate reclamation timing

Regulatory Information

Management Practices

Researchers studied old maps and walked the grounds with magnetometers, which detect the magnetic field from metal casings in the wells. If casings were never installed or had been removed, they could test the soil for hydrocarbons that might be leaking to the surface.

The actual well abandonment operation involves: well entry preparations (including setting-up load spreaders, installation of back pressure valve, and the nippling-up and testing of blowout prevention equipment), use of slick line unit (including confirmation of the presence or absence of wellbore obstructions, verification of measured depths, and the pulling of downhole safety valves), filling the well with fluid (including establishing an injection rate into open perforations, and pressuring-up the tubing and annulus to verify integrity), removal of downhole equipment (including the pulling of pumps and tubing strings), cleaning out the wellbore (utilizing casing scrapers and a variety of special purpose fluids), plugging open-hole and perforated intervals(s) at the bottom of the well (including squeeze cementing, setting cast-iron bridge plugs, or the placement of cement plugs), plugging casing stubs (where casing has been cut and recovered), plugging of annular space (using squeeze cementing techniques), placement of a surface plug, and placement of fluid between plugs. Regardless of the technique used, plugs must be tagged to ensure proper placement and/or pressure-tested to verify integrity.

I.  Groundwater Monitoring

II. Abandoned Mine Lands

Design and oversee the reclamation of a variety of hazardous or environmentally degrading mine-land problems, including mine openings, landslides, highwalls, erosion, toxic spoil, subsidence, and acid mine drainage. Dangers within the mines include poisonous or explosive gases, oxygen deficiencies, flooded sections, unstable roofs, hard-to-see vertical shafts, venomous insects, poisonous snakes and disorienting mazes of mine workings. These problems are compounded by total darkness within underground mines.


Spoil banks from surface mines, coal waste piles, and natural slopes at abandoned mines sometimes become unstable. The most common causes of landslides include the following: steep slopes; saturation of slopes by water from underground mines, surface mine pits, or natural aquifers; and the inherent instability of the disturbed materials. Landslides can damage roads and buildings, and can block paths of streams, causing upstream flooding.

Highwalls are created during surface mining as sides of hills are removed to expose coal seams. Rock faces resembling cliffs remain at the point where the mining excavation ceased. Before stricter reclamation laws were passed, miners were not required to backfill mine spoil against highwalls. Thus, there are many miles of highwall remaining in Ohio. Typically, they range in height from 20 feet to 100 feet. The degree to which they pose a danger to the public is determined by proximity to human dwellings or activities and to public roads; stability; and heights and angles.


Erosion and sedimentation from AML lands often cause flooding problems by clogging stream channels and culverts. Extensive amounts of reclamation have been done to eliminate AML sediment sources in southern and eastern Ohio.

Acid Mine Drainage (AMD)

Rock layers associated with the coal seam sometimes contain iron sulfide minerals, with pyrite the most common. Sulfur-bearing materials exposed to air and water during mining react with oxygen and water to form dilute solutions of sulfuric acid which may also contain a number of other dissolved minerals. This contaminated water, referred to as acid mine drainage (AMD), often seeps from underground mines and sometimes from surface mined areas. AMD is a significant environmental problem associated with abandoned mined lands and is often very difficult to control. Over 1300 miles of Ohio streams are impacted by AMD.


More than two billion tons of coal have been removed from underground mines in Ohio since the 1800's. In the early days, many mines were never surveyed. Thus, no maps exist to describe the extent of abandoned underground mines. Mine subsidence is also a common problem caused by abandoned underground mines. Projects are often undertaken to fill in and stabilize the mines most likely to cause subsidence damage.

When buildings are constructed above mines, major damage to walls and foundations can occur if the mine subsides. Most insurance policies do not automatically cover mine subsidence damage to your home.

III. Wells

IV. Pipelines


  • Re-use / Re-cycle
  • Leave In-situ 
  • Partial Remove / Leave In situ
  • Remove & Dispose
  • Remove & Recycle

Purge and cleaned internally to remove all remaining hydrocarbon and residues from hydrocarbon production (wax, scale, etc.)

  Leave in Place / In situ Method
  • Most common method
  • Technically proven 
  • After cleaning, filled with suitable abandonment fluid such as:
    • Oxygen scavenger
    • Biocide
    • Corrosion inhibitor
    • Other additives (depend on pipeline metallurgy and physical condition)
    • The end are capped and buried
  • Safety concerns
    • Long-term:
      • Deteriorated pipeline may cause problems if not properly purged and abandoned
      • Normally remaining life of anode will be in range 40-350 years (majority in range of 40-80 year)
    • Environmental concerns
      • Minor use of energy consumption and emission release
      • Some heavy metal (Hg, Cd) in pipeline and anode may have negative impact to environment after deterioration
      • Potential for leakage of preservative fluid.

Progressive pigging - series of polyethylene foam pigs through pipeline with chemical agents and flush water to remove all hydrocarbons. Verification is based on flush water quality check/ visual verification (no hydrocarbon sheen).