Dredging of the Rotoaira Canal and deposition of the resulting silt is an on-going issue for Genesis Energy’s Tongariro Power Scheme.
Cheal has assisted Genesis Energy in this area for over 15 years through survey monitoring of sediment levels in the canal as well as the provision of engineering services. With the previous sediment disposal area at capacity, a new location within the Rotoaira Forest was selected by Genesis for use with the next three dredging cycles (approximately 300,000m3). However, prior to the first dredging (100,000m3), the site required preparatory works including construction of a 3m high bund along the lower portion of the site as well as drainage works—consisting of an open channel and 220mof pipe.
The design, construction, supervision and contract management aspects of the project were all carried out by Cheal on behalf of Genesis Energy. The construction of the bund and drainage works was monitored weekly by Cheal personnel with site meetings to review quality control, health and safety, environmental and programme aspects of the project. The result was a well constructed bund and drainage system within the required time frame.