Offering a Broad Range of Horizontal Auger Boring Services
Casing sizes that we install range from 12" to 84" in diameter and from 0 to 500' long. This type of boring is performed in both cohesive and granular type soils free of large rocks/boulders or large concentrations of cobbles or large gravel or high water content.
This method is generally used when a steel casing is required to be used as a liner for a smaller utility to be installed inside the casing.
Prior to Bull’s-Eye Boring’s arrival onsite, line and grade/cut stakes are set by others. Upon our arrival on-site, the contractor’s personnel verify and show our personnel line and grade stakes along with other pertinent information regarding the casing installation. Bull’s-Eye Boring then sets the rails and bore machine in the bore pit at an elevation to properly install the casing at the proposed line and grade. Starting the casing straight is the key to line and grade control.
Further grade control is achieved utilizing a special steering head (similar to the gallery picture). The casing is cut several feet back from the end and hinges are installed on each side. In granular soils, thin steel (sand band) is placed over the cut to prevent material from entering the casing through the cut. A special knuckle is mounted on top of the casing on each side of the cut. Just prior to the casing being installed in the ground, a ½” steel pipe (with ½” block) and a 1-½” steel pipe are mounted to the top of the casing. A smaller pipe (steering rod) is placed inside the 1-½” pipe. The steering rod attaches to the knuckle as shown in the picture. The 1-½” pipe is to protect the steering rod and allow it to be turned one way or another during casing installation. As the casing is pushed through the ground, the bore machine operator may determine that the casing needs to go up or down. The steering rod may be turned one way or another in the bore pit; this will turn screws inside the knuckle pushing/pulling the cut section of casing down or up as required. A flexible hose is connected to the ½” steel pipe and attached vertically to a board in the bore pit. The ½” pipe can be filled with water at anytime from the bore pit. Because water seeks its own level, the exact grade of the casing can be continuously monitored and adjusted as required. If Bull’s-Eye deems necessary, the augers may be withdrawn from the casing to verify the grade of the casing at various intervals during the installation. Further control of line is achieved manually utilizing shoes installed on one side of the casing or the other. If the augers are withdrawn from the casing, grade is checked and line is checked. If line requires adjustment, a steel shoe is placed on the exterior of the casing to push the casing in the proper direction.
Because of the way conventional bore and jacking operations are performed—access to the face of the casing is necessary for a successful bore. Therefore, when we are asked to bid a project and an engineer specifies a 12”, 14” or 16” casing, we generally will upsize to a minimum of a 20” casing (and sometimes larger depending on the situation) so that we can properly guide our casing. Because of the steering knuckle (shown in the gallery picture) that is mounted to the top of the casing (it is approximately 4” tall), we always request a 1’ clearance from any utility. Additionally, this clearance helps so if in the event we hit an obstruction near the utility, we do not push it into or through the utility.
PILOT TUBE METHOD:
Casing Sizes that we install utilizing this method: 4" to 60" diameter and from 0 to 600' long.
This type of boring is performed in both cohesive and granular type soils free of large rocks/boulders or large concentrations of cobbles or large gravel or high water content.
This method is generally used when a steel casing is required to be used as a liner for a smaller utility to be installed inside the casing AND line and grade is critical. While conventional boring is accurate, we generally select this method for extremely tight tolerances or longer casing installations.
SOLID ROCK BORING:
Casing Sizes that we install utilizing this method: 24" to 54" diameter and from 0 to 400' long.
This method is much like conventional boring with the exception of the cutting head. We have different cutting heads for solid rock (including Christmas Tree style and Robbins "SBU" Small Boring Units). For shorter bores, we may utilize a Christmas Tree style head to cut the rock. For longer bores or bores requiring more accuracy, we utilize a Robbins SBU. For both types of cutting heads, the bore must be completed in a full face of solid rock for the entire distance. We recommend the Contractor dig test holes at both ends of the bore and design the casing such that the top of the casing is several feet into the rock. We ask that the Contractor pour a concrete starter block where the casing will enter the ground—this allows our rock head to be started straight into the ground vs bouncing all over a jagged face of rock. For this method, grade control is achieved utilizing the SBU. Please contact our office if a partial face of rock and dirt will be encountered in the bore for recommendations on the proper installation method.
SLICK BORING:
Sizes that we install utilizing this method: 4" to 60" diameter and from 0 to 600' long
This method is generally used when installing a steel pipeline and a casing is not desired around the pipeline. For this method, conventional boring, pilot tube boring, or rock boring are all an option. For this method, we install a temporary pipe (the same size as the pipeline) utilizing one of the previously mentioned options. Following the temporary pipe installation, the pipeline Contractor we are working for welds the permanent product pipe to the temporary pipe in the bore pit. We push the product pipe into the ground, subsequently pushing the temporary pipe out in the far receiving pit. The temporary pipe is cut out and salvaged. Product pipes are continually lowered into the bore pit and welded and pushed until the product pipe reaches the receiving pit.