Background

Tarbotton Land & Civil has a long history for building successful water storage ponds from start to finish.

Tarbotton, alongside Bell Geoconsulting Limited, completed a design and build for two large water storage ponds (irrigation pond and effluent pond) in Mid Canterbury. The two ponds, given the name Twin Ponds, were designed to hold approximately 150,000 cubic meters of water and effluent.

Planning

First, the client provided a minimum storage capacity required for the two ponds along with a preferred location. The Tarbotton team went and surveyed the site along with the existing irrigation infrastructure and combined this with the future infrastructure plans. This enabled the team to optimise the best footprint and shape of the new ponds while allowing maximum pivot irrigator spans across the farm.

Design & Consenting

The team met with the client and other key stakeholders involved regularly throughout the design process. A minimum storage volume was specified along with the footprint. The team worked hard to optimise the cut to fill volumes reducing construction costs.

We worked with Environment Canterbury and the Ashburton District Council to obtain the required consents before construction which included land use consents, earthworks consents and a construction phase stormwater consent. The ponds were also constructed with the Building (Dam Safety) Regulations and New Zealand Society on Large Dams (NZSOLD) Dam Safety Guidelines in mind.

Construction

The two ponds were constructed on virgin ground and the topsoil and clay layers were stockpiled separately for future use. Bulk earthworks were completed using CAT 627G scrapers, a 36-tonne excavator and articulated dump trucks. Leica GPS machine control systems were used to ensure the pond was constructed within 5mm of the digital design. The two ponds were constructed as independent structures lined with a 1.5mm HDPE liner over an underlying gas drainage system and geomembrane.