U.S. EPA Contaminated Site Cleanup Information (CLU-IN)

U.S. Environmental Protection Agency
U.S. EPA Technology Innovation and Field Services Division

Horizontal Remediation Wells


History of HDD

HDD was developed by the oil industry in the 1930s and adapted for utility installation in the 1970s. Its application for installing horizontal remediation wells (HRWs) grew in the late 1980s with demonstration projects sponsored by the Department of EnergyAdobe PDF Logo.

Horizontal directional drilling (HDD) has been used to install wells for the extraction of oil and natural gas since the 1930s. HDD was used subsequently for underground utilities, and then in the late 1980s, the technology was repurposed for environmental remediation applications. These are some of the remediation technologies that can be implemented with HDD. (For specific site examples, visit the Site Application Examples.)

Schematic of an SVE/Air Sparging System that
Incorporates Horizontal Wells. (EPA, 2017Adobe PDF Logo)Schematic of an SVE/Air Sparging System that Incorporates Horizontal Wells
Zoom In

In addition to remediation, horizontal wells are used for:

  • Injecting treated water back into the subsurface to reduce the potential for groundwater mounding and other adverse gradient changes associated with vertical injection wells.
  • Controlling the migration of groundwater plumes and capturing leachate from landfills for treatment.
  • Sampling groundwater.

Sampling from horizontal borings and wells has an advantage over vertical wells when determining if contamination is present beneath or is migrating from surface or subsurface obstructions. For example, samples can be collected below landfills without puncturing liners. Custom soil and groundwater sampling equipment have been developed for use with HDD equipment. Downhole geotechnical equipment such as logging tools, resistivity probes, and miniature cone penetrometers are also available for use in horizontal wells.

Top of Page