Ellingson crews recently completed the installation of two horizontal injection wells underneath the active flight line area of an eastern US Air Force base.
The total bore lengths measured ~1500ft, however the installed wells consisted of only 1250ft of casing and screen. The crew installed the wells in a double-ended configuration (which included an exit in the infield of the flight area). The exit curves were simply grouted since wellhead infrastructure in the active portion of the airfield was unnecessary.
Exiting within the infield presents many challenges for a horizontal directional drilling (HDD) operation. Had the site geology been more cooperative, we’d prefer to have installed these wells “blind” or “single-ended”.
Unfortunately, the ground conditions don’t always cooperate. These type of complicated infield operations require careful site coordination with base personnel (and lots of vigilant FOD checks!)
Horizontal directionally drilled (HDD) remediation wells offer many different advantages over their vertical counterparts. Emplacing screen in “difficult access” locations features prominently towards the top of the list.
This access advantage really shines at air force facilities. There’s lots of jet fuel in and around the airfield, and over the years it makes its way into the subsurface as soil and/or groundwater contamination.
As mentioned earlier, getting access to the infield is extremely complicated. Driving equipment (like a drill rig) around the flight line is incredibly disruptive. And while environmental remediation remains an important goal, the primary mission of the air force base still needs to come first.
Directional drilling allows the contractor to install screen immediately beneath the flight line or taxi areas, while keeping **most** of the drilling operation comfortably out of the way of flight operations.
Of course, due to geological conditions, this project required some equipment and activity in the infield. However, even that disruption proved minimal compared to many other alternatives.