Horizontal Directional Drilling (HDD)

DM Civil has undertaken some of the largest diameter and longest HDD drill shots for Water Corporation.

In 2002, DM Civil constructed the 13.5km DN375 Eaton to Kemerton wastewater pressure main. The pipeline was largely PVC pipe except for the crossings of the Collie and Brunswick Rivers. These two river crossings were constructed below the riverbeds with HDD bores of 400 metres and 600 metres length respectively.

DN150 pilot rods were drilled into position utilising induced magnetic field to track the steering head. After the pilot rods were in place, the hole was reamed out using incrementally increasing sizes of reaming tool. After the final DN600 reamer had completed the hole, the drill end was attached to a pre-welded pulling head, connected to a pre-tested DN400 PN20 polyethylene pipe string, and pulled into position in a single continuous pull-back operation.

The Collie River crossing was a relatively simple, standard catenary shaped drill and pull back operation. The 600 metre Collie River Crossing was more a complex operation, comprised of multiple curvatures and requiring two horizontal and three vertical changes in direction.

In 2013, DM Civil delivered an alternative construction methodology, installing 410 metres of DN200 PE with an HDD drill. This was installed in the township as a part of Dwellingup’s new water supply scheme. Our alternative methodology provided considerable, safety, environmental and stakeholder management benefits to the originally proposed open cut excavation.