Milestone reached on water supply

A consent application for the Waikanae River Recharge scheme has been lodged with the Greater Wellington Regional Council.

Mayor Jenny Rowan said the lodging of the application was a significant step forward.

“The issue of a secure supply of good quality water for Waikanae, Paraparaumu and Raumati residents has been a much debated issue. This Council promised to move this issue forward, and it has.”

Council already has existing consents to take up to 23,000 cubic metres of water a day from the borefield and the Waikanae River. It wants to increase this by one-third to 30,700 cubic metres to cover expected population growth over the next 35 years – the longest period of time a resource consent can be issued for.

Water Supply Project Manager Phil Stroud said Council had taken a very conservative approach in all aspects of the project. “We are basing our modelling on medium population growth figures, a contingency factor on top, and a 50-year drought scenario to ensure we have enough water to cover every eventuality.

“To put this in context, we are only seeking permission to use up to 2.6% of the underground reservoir in a worst case scenario – a 50 year drought. The cubic metres figures by themselves sound a lot, but in context they are not.”

Mr Stroud said scientists had closely studied what impact the underground water could have when mixed with the Waikanae River.

A considerable amount of research had also been carried out on how the Waikanae aquifers worked, the amount of water available underground, the relationship between the various aquifers, issues surrounding potential draw-down, and whether there was any threat from saline intrusion.

“Our consultants say there is only a low risk of saline intrusion. Despite this, we are taking a very conservative approach and we won’t use any bores within a kilometre of the coast. All but one of the existing bores is considerably further inland.”

Initially it was thought 30 to 50 existing private wells (out of around 3000) could suffer from draw-down during a worst case scenario. Subsequent checks suggested the numbers could be considerably less and that any impact could be easily dealt with. The potential impact on local wetlands was found to be less than the impact of normal seasonal variations.

Mr Stroud said the Greater Wellington Regional Council intended to publically notify the consent process later this month. Members of the public would then have an opportunity to make submissions on the consent application before the Christmas break.

“We understand the hearings will be conducted by Greater Wellington in mid-February 2013 with a decision in mid-March. We need to make clear that the consenting process is run by Greater Wellington and independent of this Council.”