Such is the case with an installation DTD completed in late October. The soil contamination from the dry cleaning operation extended beneath two stores within a strip mall; both spaces occupied by busy restaurants. Accessing the soil below the building floor would require either a complete building tear down, or traditional vertical remediation wells. Vertical drilling would require temporarily closing the restaurants to bring in a mini drill rig and create significant cost effect on the diner’s owners Rather than disrupt the businesses, the wells were installed by horizontal directional drilling (HDD) allowing the businesses to continue normal operations.
DTD has applied HDD to a number of sites like this. At this California location, we set up the drill rig in the back ally, and drilled six horizontal remediation wells beneath the two restaurants. The wells trend directly beneath the kitchen and service area, terminating under the restaurant dining room. Since all drilling operations were from behind the facilities, there was almost no evidence of the drilling operations. In fact, all wells were installed during normal business hours without any impact to the operation of the restaurant. The patrons of one eatery with a very busy lunch crowd did not even know wells were being completed under their feet.
Each well was completed in a blind (single entry) borehole with a total length of 71’. The screen and casing materials are composed of 3” diameter PVC screen (45’ – installed at 4’ below the building slab) and riser (26’). Sodium permanganate will be injected into the wells as part of the remediation strategy at the site. Subsurface conditions were fill material and high plasticity silts. Biodegradable drilling fluids were utilized and well development consisted of jetting a fresh water/enzyme based breaker solution.