St Mary’s Bay/Masefield Beach water project

 Application for a resource consent for the St Mary’s Bay/Masefield Beach water project is expected within the next month. The project will involve a 1.8m diameter pipe being drilled under the cliff line in the St Mary’s Bay Reserve and Auckland Council is in the process of contacting all owners of affected properties to discuss potential impacts of the project.

Water quality in St Mary’s Bay/Westhaven has been an issue for the Association for many years, with contaminated water from the drainage network regularly overflowing into the bay.  The overflows occur whenever the amount of stormwater entering the combined system causes the total flow to exceed the carrying capacity of the old pipes (essentially because the volume of stormwater is unpredictable).

St Mary’s Bay is not alone in the central Auckland isthmus in suffering contamination from overflows from a combined wastewater/stormwater system constructed in the early 1900s.  However, we do have some of the worst, and into waters that are used extensively for recreation.  The contamination from these and similar overflows in Herne Bay also affects local Herne Bay beaches that many of us use.

Council’s Healthy Waters section (with responsibility for stormwater) has been working for several months on a project to capture and hold the overflows into St Mary’s Bay prior to feeding the water back into the system as soon as it has capacity to receive it.  Some residents may have attended public information meetings last year about this.

The project comprises a large (1.8 metre diameter) pipe being drilled under the St Mary’s Bay clifftop, running from a point near the eastern end of London Street, under the reserve at the foot of St Mary’s Road, and back under the cliff near the western end of Ring Terrace and fringing lower Shelly Beach Road, before emerging from a portal below Point Erin.  The pipe is big enough to hold most overflows, but where its capacity is exceeded, the excess will be pumped into a pipe running from a pumping station at the base of Point Erin, to a discharge point near the channel running under the harbour bridge (where, hopefully, it will disperse quickly with tidal movement.  The pipe may also be used to collect water from pipes in Shelly Beach Road and parts of Sarsfield Street that were contributing to overflows in Hackett Street.

The Association wishes to support any project that stops the overflows, but has several concerns about this one.  It has met with Healthy Waters on a couple of occasions to discuss these concerns, and will continue to do so.  The concerns, in summary, are:

  • Stability of the clifftop.

This is vitally important to property owners above, but is also important to us all as the cliff and its cover of vegetation provide a visual amenity for all.

  • Impact on the reserve.

The Association went to great lengths to ensure that the reserve area was preserved for recreational use when the bridge approach was widened.  It is a valued amenity for its many users, and use will be affected during construction.  Furthermore, the proposed pumping station at the foot of Point Erin will intrude significantly on that open space.

  • Shifting the problem.

The Association is aware of the proximity of the Herne Bay beaches to the outfall pipe and that the waters off Masefield Beach are being used increasingly for small boat sailing.  Even accepting that the volume of stormwater in any discharge means that wastewater will be diluted, and the volume of discharge is likely to be low by comparison to the receiving water under the harbour bridge, and be dispersed reasonably quickly by the current, it still entails a shifting of the problem onto someone else’s patch.

Conversely, it will not resolve the problem of contamination around the western bays, and  there is concern that the overflow contamination from those areas will flow back into Westhaven and St Mary’s Bay, reducing the efficacy of this project.

  • The cost of the project measured against the level of improvement of water quality.

Healthy Waters has devised the project to provide substantial improvement rather than a complete fix.  It says that it will reduce the overflows significantly as soon as it is constructed (by 2021) and almost entirely when a very large collector pipe, called the central interceptor, is built through the central isthmus to take water from the combined system to Mangere (2026).  Until the central interceptor is built, heavy rainfalls will continue to result in discharges into the harbour (as the retained overflow can only be returned to the combined pipe system when it has the capacity to accept it    Once the central interceptor is built (it will start in Grey Lynn, near the Countdown supermarket) water from the St Mary’s pipe will be piped across to it – and Healthy Waters says that the discharge pipe will only have to be used on a couple of occasions a year, at times of very large storms.

The Association believes that best way to stop wastewater overflows is to have separate wastewater and stormwater systems.  Separation of the combined pipe network in the St Mary’s Bay and Herne Bay catchments is being considered as part of a planned upgrade of the combined system in the western isthmus (the central interceptor is part of that plan).

In addition, it is still concerned that there are other outfalls in St Mary’s Bay that have not been identified and picked up by this project that will continue to discharge into the bay.

The Association accepts that the project has the potential to improve water quality in the short term, but is concerned that it will not be a complete panacea.  It is continuing to meet with Healthy Waters to explore solutions to these concerns, and explore whether there are options will achieve better long term outcomes for the cost involved.

In the meantime, Healthy Waters is moving ahead with the project.  It will be contacting all owners of properties above the line of the storage pipe to discuss potential impacts of the project on them.  If you are one of these owners, and have not yet heard from Council, please let us know and we will raise that with Healthy Waters.  In addition to that private consultation, Healthy Waters will be making an application for a resource consent for the project.  We expect that to happen within the next month.  It will be notified publicly.  We will let you know when that happens, and canvass views at that point as to how we, the Association, wishes to respond to it.