Environmental & Foundation Drilling Inc. recently utilized its rig's ability to drill steel casing into bedrock without the need for an enlarged borehole and grout.

Environmental & Foundation Drilling Inc. (EFD), headquartered in Waunakee, Wis., was contacted by a Midwest barge contractor who was aware through his contacts in the drilling industry that EFD had a rig with the ability to drill steel casing into bedrock without the need for an enlarged borehole and grout. The project on which EFD was subcontracted included the installation of three 12-inch steel pilings into 15 feet of limestone bedrock. The difficult part of this project was that the bedrock was located at the base of a scoured river bottom with little or no sediment overlying the bedrock surface. It was understood that standard rotary drilling methods would be not be applicable here due to the fact that the hole would be started directly on the bedrock surface, which was found under 15 feet of water. The pilings were to be used as an anchoring system for an addition onto a water treatment intake facility.

EFD proposed to set up its Barber DR 24 rig on a series of barges that could be adjusted to obtain an opening for advancement of the drill stem. A Barber DR drill has two separate rotary drives. There is an outward pivoting tophead that has the ability to turn standard drill pipe, as well as dual tube applications. The lower drive is a large hydraulic ring gear that clamps onto steel casing. The lower drive cannot only spin the casing in the ground, it also advances the casing using down pressure. Drill rods and steel casings are loaded from the rear using the outside pivoting tophead, along with the assistance of a winch or crane behind the rig.

The rig was loaded some 75 miles away from the project location at the barge contractor's facility. Because of his wealth of experience, the barge contractor was perfectly prepared to adjust his barge configurations to adapt to the special needs of the drill. The barge was mobilized to the drilling location overnight, with the tugboat picking up the drilling crew the next morning just upstream from the drilling site. Setup of the barge once they reached the drill site was less than one hour, showcasing the competence of the tugboat crew. They were able to pinpoint the drilling location quickly, dropping large I-beam spuds into the river bottom to stabilize the barge position. EFD's crew then set to work on drilling the borehole. Once the casing sections were welded and the drill rod connected, the drilling commenced. It should be noted that starting a cased borehole directly on bedrock must be done carefully to avoid deflection of the casing and a crooked installation. The drilling crew has performed this operation many times and the installations all were perfectly vertical.

Along with advancing 12-inch casing tipped with a carbide-studded shoe, the interior relief hole was drilled using a 12-inch DTH with 10.75-inch drill rod. The larger drill rod was chosen on this occasion to reduce the annulus between the outside of the drill rod and the interior of the steel casing. The limited space on the barge didn't allow for an extra air compressor, so decreasing this annulus assisted in increasing the hammer's efficiency. This rig is equipped with an onboard 950-cfm/350-psi air compressor but additional air power can increase drill times significantly. Even given the limitations of drilling on the barge, an analysis of the cuttings showed the rock hammer was working well and steady advance rates were obtained. The first casing was set into place and EFD's crew moved on to the second location by early in the afternoon of the first day.

The completion of the second piling occurred by midmorning on the second day. Movement to the third location was hindered by high winds and rough water. The tugboat operators were very careful in their movements as the high winds caused the barge to pitch slightly. Even with these conditions, the crew was more than up to the task. The drilling operations decreased in time from hole to hole as the EFD crew became familiar with the working environment and texture of the bedrock. Upon completion of the last piling, the barge returned to its home port, taking advantage of the overnight travel time. Unloading the rig and drill rods took place the next day. The project was finished one day early and on budget.

Contractor Profile

Environmental & Foundation Drilling Inc.
217 Raemisch Road
Waunakee, Wis. 53597

Through the leadership of co-owners Matthew Hood and Gregory Anderson, Environmental and Foundation Drilling Inc. has been growing and serving the needs of engineering and construction professionals for over 14 years. The firm has performed over 4,500 projects for hundreds of different engineering, construction and public sector agencies. The projects have included 5-foot auger holes for pavement design parameters to 1,300-foot high capacity water wells. EFD has worked on many industrial sites and superfund jobs that required the coordination of many rigs.

The company's modern line of CME auger drill rigs are capable of drilling with hollow-stem augers from 2.25 inches to 12.25 inches, as well as a variety of mud drilling, rock coring and air rotary methods. The drilling platforms are mounted upon trailers, single- and tandem-axle trucks, or all-terrain carriers that are capable of off-road uses. Environmental & Foundation Drilling also is equipped with a full line of drilling tools and support vehicles, including heavy-duty 4-by-4 pickups, flatbed water trucks and self-designed mobile decontamination trailers.

Complementing the auger rigs are two Barber dual rotary drill rigs and a Gus Pech Super 48 bucket auger rig. The Barber has the ability to advance casing and standard drill pipe simultaneously, as well as dual tube drilling applications. Bedrock, heaving sands and cobbles are drilled and cased efficiently, making deep holes installed in difficult drilling mediums cost effective and realistically obtainable. This machine is capable of installing prebored piles, elevator shafts, discreet water sampling dual tube borings and large diameter recovery wells. The bucket rig has many construction-related abilities, including holes for caissons and landfill vent wells.

All drillers and technicians employed by EFD have completed the OSHA-required 40-hour health and safety training course, as well as yearly eight-hour in-house refresher courses. Furthermore, all employees are first aid and CPR certified. In addition to their classroom training, employees are medically monitored with yearly comprehensive exams.