A big advantage of directional drilling is the ability to set up the drilling equipment some distance away from a contaminated zone, particularly if the zone is situated under an active commercial or industrial site. DTD recently wrapped up two projects in Indiana that illustrates this capability. The projects required the installation of 3 Air Sparge wells, one SVE well and one conveyance bore. Both projects took a total of 10 days to complete, including mobilization to the second project.
The first project, located near Layfette, IN, entailed the installation of 3 Air Sparge (AS) wells for remediation of petroleum impacted soil and groundwater below an active gas station facility. The horizontal AS wells will become part of a dual phase extraction system where the vertical extraction wells already exist on site. Working closely with the client during the design phase, DTD assisted in the design, then installed the well array beneath the service station, arranging all of the wells to converge to a single point for easy connection to a blower system.
The 3 horizontal wells were drilled and installed at a depth of 20’ and were placed and screened to be within the extraction zone of the vertical wells. Once completed with the wells DTD drilled a single bore from the location of the well heads, under an ally and exited the ground where the client plans to construct the compressor station. Three conveyance lines where then pulled back and plumbed into their corresponding well heads. The job was completed with the installation of a vault around the three wells.
Following these installations, DTD then mobilized equipment about 3 hours east to the site of a small engine repair shop.
One well was installed at this site. This SVE well is 125 feet in length, passing under the floor of the active shop area. Due to the well’s shallow depth, great care was taken in locating utilities along the bore path and particularly at the exit end, where several utilities were known to be present.
One aspect of directional drilling that requires forward planning is the management and disposal of drilling derived waste. Directional drilling is accomplished with a drilling fluid that is pumped down the drill rods to assist in cutting, remove drill cuttings from the bore, and support the hole until the casing and screen can be placed. On average, a drilling operation will generate from 3 to 5 times the volume of the bore in waste cuttings and drilling fluid. DTD recommends that this waste be captured in a closed or open-topped rolloff container.
The waste is pumped from the entry pit as a slurry – which will typically require solidification or other treatment before it will be accepted at a disposal site. At both of the Indiana sites, a product called “Zap-Zorb” was used to thicken the slurry into a gel-like sludge of a viscosity acceptable to the disposal facility.
Both of the Indiana projects were completed on time and within budget. The result is that DTD will soon be returning to Indiana for one of the clients to complete another remediation project at another service station site.