The Drain That’s a Pain (and falls partly in the Domain)
Sometimes a seemingly obvious solution can turn into a major obstruction, and so it was with a Council-owned drain along one boundary of a development in Casebrook.
The drain in question was a so-called “box drain” of the type common all around Christchurch. It was about 1.5m square with timber sides held apart at the top by timber braces. It straddled the boundary of the development with the neighbouring Christchurch City Council reserve for a length of about 400m, and had last been maintained some time in the 1980s. Upstream of the development a small spring had been the only source of water flowing into the drain, and so that section of the drain had previously been filled in and replaced with a 150mm pipe.
Why Removing the Drain Wasn’t So Simple
If the drain was left in place, it would trigger the requirement for a 7.5m waterway setback on any neighbouring lots, severely restricting the building platforms of the new lots we were creating. The presence of the drain would also create questions around land stability. Considering this and looking upstream at the length that had already been piped, we naturally thought the simplest thing would be to deconstruct the drain, fill it in with solid material and extend the existing pipe through our development.
We had anticipated needing consent to fill the drain in, but what we hadn’t expected was that, because the drain was classified by Environment Canterbury as a river, we would need a total of four different consents – for diversion, realignment, spring protection and works within a waterway. On applying for the relevant consents, we quickly ran into one unexpected hurdle after another. An old pre-1900 record map showed a drain in the general area, so the drain became a heritage matter for which archaeological authority had to be sought from Heritage NZ. We were also required to undertake an investigation of the ecological values of the drain which revealed the presence of some fish species.
The Final Outcome
Eventually after two years and about $100,000 all of the relevant consents and authorities were obtained. Around 300 fish were relocated and a screen installed to prevent repopulation. Most of the drain was deconstructed and the surrounding soil excavated. The resulting trench was backfilled, using a high-tech robotic compacter to avoid the need for workers in the trench. Soil profiles were recorded at intervals along the drain for archaeological purposes, and a 4-5 metre length of the drain near a public walkway was retained for posterity. This section is surrounded with concrete and grated over, and an interpretive plaque will be installed.
While we have arrived at a good solution, it has required an enormously inefficient and expensive bureaucratic process to get to this point. Other consultants thought that we wouldn’t be able to gain the necessary consents, but the expertise of Fox and Associates and the other consultants involved, along with good will from all stakeholders including staff from Environment Canterbury and the Christchurch City Council helped win the day. Surely it doesn’t need to be this difficult though.
