Lake James is an existing homogeneous earth fill dam located on a minor tributary of the Hunter River. The dam is owned and operated by Rio Tinto Coal (RTCA) Hunter Valley Operations (HVO).

The existing embankment crest was raised by a total of 2.3m. The method of construction was primarily centreline construction, ie earthworks were undertaken both upstream and downstream of the existing embankment.

In addition to the embankment construction, the works included upgrading of ancillary structures, excavation of clean water diversion drains, construction of sedimentation basins, and installation of stormwater culverts.

The Project presented many significant challenges including the constraints of space, time and the order in which materials were sourced, conditioned, excavated, placed and compacted in order to form the embankment.

The construction of the Lake James embankment involved the placement of three principle material zones:

• Zone 1 which formed the central impervious core of the embankment consisted of sandy clay and required careful and well planned moisture conditioning in order to meet the requirements of the technical specification.
• Zone 2A material consisted of naturally occurring alluvial sands that were placed on the downstream face of the existing embankment.
• Zones 3 rock-fill material formed the upstream and downstream shoulders of the embankment. This material was sourced from an existing quarry within the mine. Careful sorting and selection of material was required in order to ensure the specification in relation to material quality was maintained.

The Daracon plant fleet for this project included 45 tonne excavators, 35 tonne excavators, CAT 740E Articulated Ejector Dump Trucks, D6 Bulldozers, 14H Grader and CAT 740 Watercarts, along with a range of supporting compaction equipment.

A collaborative and cooperative approach to dealing with design changes and changes in scope ensured the project was completed with a high level of Client satisfaction.