DHML was contracted between 2000 and 2002 to construct the Ashburton Aquatic Park (now Lake Hood) for the Ashburton Aquatic Park Charitable Trust.
Lake Hood is situated 6km from the town of Ashburton, mid Canterbury, in the South Island of New Zealand. With a value of $4.3M this project entailed construction of a 120ha park including recreational lake and subdivision on a river terrace of alluvial shingles adjacent to the Ashburton River.
The 80+ ha lake stores about 1.3 million litres of water, and boasts more than 7km of shoreline, an 8 lane international standard rowing course, and the first stage of a 150-section subdivision development.
Earthworks volume totalled 960,000m3. A main embankment was constructed consisting of bulkfill, a subliner, liner and erosion protection layer. A substantial area of the floor required lining with an imported material using a methodology developed on site.
This project required a full time quality control technician including a materials laboratory and up to two full time surveyors to meet tolerances and match production.
GPS survey control and measurement was used throughout the project including 3D machine control of a 627 scraper. Volume calculations were completed using the LDD software package.
The use of Trimble’s GPS Site Vision was employed on one scraper. This enabled the complex canal shapes and subdivision platforms to be constructed efficiently with minimal input from survey staff. This system also assisted a fleet of up to 7 scrapers with the bulk earthworks within the lake footprint.
Liners & compaction
Limiting water seepage to meet stringent resource consents specifications, and working to a tight budget were among some of the major challenges. The major technical difficulty was consent requirements governing seepage of the lining on the bottom of the lake and the embankment.
Construction difficulties were experienced with ground conditions and tolerances specified for compaction as the lake was constructed over existing floodplain cobbles.
The project was successfully completed in 2002.