Project Description
Foundex was engaged in 2016 to complete the drilling and installation of near‑horizontal and upward‑inclined drainage holes to support long‑term slope stability and groundwater management at a dam structure. The program included fifteen drain locations, spaced along a slope based on site geometry and hydrogeological requirements. Ten drains were positioned upstream of infrastructure aligned perpendicular to the hillside, with anticipated drilling lengths ranging from approximately 85 to 95 metres. Downstream of the infrastructure, a five‑hole array was installed on close spacing to prevent cross‑communication and maintain drilling efficiency, with target depths extending up to 130 metres.
Foundex worked closely with the client to establish suitable drill pad locations, site access, and safe working platforms. Pad construction included provisions for drainage, spoil containment, and environmental controls required to manage water and cuttings throughout drilling and installation. Once established, each drill site was surveyed to confirm collar coordinates, inclination, and azimuth required to reach the defined subsurface targets.
To complete the program, Foundex mobilized a horizontal drilling system (HT‑2000) designed for long‑reach, controlled‑alignment drilling in complex terrain. Reverse circulation drilling methodology was used, as this approach emphasized maintaining alignment, efficient cuttings removal, and stable borehole conditions to support the installation of PVC drainage pipes. Drilling progress, alignment trends, and ground response were monitored continuously, with adjustments made as needed to reach the required endpoints.
Upon reaching depth, each borehole was cleaned and prepared for drain installation. PVC drains were advanced to the full extent of the holes and secured at the collars, allowing groundwater to flow freely into designated collection systems. Foundex crews then demobilized and moved systematically through the remaining locations, completing the full drainage program safely and efficiently.
