The resource consent for discharge from the existing treatment plant to the harbour was renewed 2013 for seven years, to allow time to get all the consents for the new plant and to build it. The resource consents for the Akaroa wastewater scheme were lodged in June 2014, as required by the consent for the existing discharge. The consent hearing was completed in May 2015 and the Hearing Commissioners' decision was received in July 2015. Consents were granted for the wastewater treatment plant, terminal pump station and reticulation, but not for wastewater discharge from the harbour outfall and other associated consents. The Council has lodged an appeal to the Environment Court, and Ngāi Tahu has joined that appeal. The full consent application and appendices are:
- Volume 1 - Application: Akaroa Wastewater Scheme Upgrading - Resource Consents Application and Assessment of Effects on the Environment (CH2M Beca, June 2014) [6.2MB PDF]
- Volume 2 - Appendices: Akaroa Wastewater Scheme Upgrading - Resource Consents Application and Assessment of Effects on the Environment (CH2M Beca, June 2014) [18MB PDF]
- Appendix B - Akaroa Harbour Modelling Report (NIWA, 2014a) [1.9MB PDF]
- Appendix G - Baseline Benthic Ecological Survey for a Proposed Wastewater Treatment Plant Outfall in Akaroa (Cawthron, 2014) [4.8MB PDF]
- Appendix L - Water-Related Health Risks Analysis for the Proposed Akaroa Wastewater Scheme (NIWA, 2014b) [1.2MB PDF]
Why the treatment plant is being moved
The current Akaroa wastewater treatment plant is located at Takapūneke Historic Reserve. In 1830, Te Rauparaha, with the help of the captain of the British Ship the brig Elizabeth, captured the Rangatira (chief) of the maori pa, Te Miharanui, and massacred up to 200 of his people on the site. It is now widely acknowledged that construction of a wastewater treatment plant at this site was an act of particular cultural insensitivity. The Council now recognises the area as an historic reserve, and hopes the site will become a National Reserve, in recognition of its significance. The Council is working with Ōnuku Rūnanga to develop a management plan for the site. Discussions have commenced with Ōnuku Rūnanga to seek their views about the deconstruction and demolition of the existing treatment plant and these works will be included as part of the whole project.
The location of the new treatment plant
In December 2011, the Council accepted recommendations from the Akaroa Community Wastewater Working Party and Akaroa/Wairewa Community Board, which reviewed different options for future wastewater treatment and the location of a new plant. The working party recommended two general locations for the plant – one north of Akaroa and one to the south. The northern site was chosen in October 2012 as it was closer to areas that may be used for irrigating treated wastewater in the future, is closer to Akaroa where reclaimed water could possibly be used in home gardens or toilets, and had better road access and power supply than other sites that were considered. This site was supported by Ōnuku Rūnanga.
The Council has purchased land at the top end of Old Coach Road for the new treatment plant site. Landowners of all suitable sites in the Akaroa vicinity were approached with the offer to negotiate a sale, and only one to the north of Akaroa agreed to do so.
Discharge to Akaroa Harbour
The treatment plant proposed for Akaroa will produce virtually clear water that looks just like tap water and has almost all of the bugs (bacteria and viruses) killed off. The treated wastewater will be safe for irrigation or flushing the toilet. Having a modern, high quality treatment plant in Akaroa will further reduce the risks to public health that may be associated with older wastewater systems, for example shellfish gathering and swimming in the harbour. Akaroa Harbour will remain a great place for tourism, aquaculture and recreation.
There are always bacteria and viruses in the water in the harbour, particularly after rainfall, coming from farm run-off and waste produced by warm-blooded creatures such as geese, dogs, seabirds, possums, marine farming activities as well as from wastewater discharges. Treated wastewater from the new plant will have almost all the bugs killed off, so it will contribute even less to the mix than it has in the past. The treatment plant will also be designed to remove nitrogen, which might otherwise stimulate undesirable algae growth in the harbour. Both the treated wastewater and the outfall pipe will be checked and monitored to ensure discharges meet all environmental regulations, and the harbour ecology and sediment are unaffected.
The outfall pipe will go into the middle of the harbour so it will be about 2.5 km out from Childrens Bay. This compares with the current outfall pipe, which only goes out 100 metres. It will be up to the contractor to decide how to install the outfall pipe, but given the relatively calm environment of Akaroa Harbour, it is likely that a trench will be dug and the pipe placed in it. The trench would fill up with sediment over time. The outfall pipe will be fully buried over its whole length in Council land and roadway and out into the harbour in Childrens Bay. The location of the outfall has been discussed with the Harbourmaster to ensure there is no conflict with cruise ship mooring sites.
The treatment plant will include concrete tanks, and a building to house noisy equipment (e.g. pumps) and the membranes. The tanks and equipment buildings for the treatment plant will have a very small footprint (approximately 65 m by 20 m) on this small (approximately 1 hectare) site. To minimise the height of the plant, some of the tanks will be partially sunk into the ground. All surrounding areas of the plant will be extensively landscaped with native plants grown from seeds sourced from nearby bush. This will include tall evergreen trees to screen the treatment plant and ensure visibility from Akaroa and Old Coach Road is reduced as much as possible. The plant will be set back into the hillside.
A new pump station will be needed in Akaroa to pump wastewater to the treatment plant. This will be located in the car/boat park next to Childrens Bay, backing onto the mini golf course. The pumping station will also include fine screens and a grit removal system to remove solids from the incoming wastewater before it is pumped up the hill to the treatment plant for further treatment and disinfection. The terminal pump station will be in a building. Landscaping around the terminal pump station will eventually mostly obscure it from view.
Wastewater treatment plants do have some noisy machinery but this equipment will be inside a concrete building. The treatment plant will meet the noise limits in the Banks Peninsula District Plan, and the nearest house is 250 metres away. The terminal pump station will also be designed to meet the noise limits in the Banks Peninsula District Plan, and to minimise noise as much as possible for the neighbouring mini golf course. There should be no disturbance to any nearby residents.
There will be some noise during construction due to the heavy machinery needed for construction. To minimise the effects of noise, construction work will be generally limited to Monday to Saturday 6:30am to 8:00pm, with no work on Sundays or Public Holidays. Some work outside of these hours may be necessary to avoid significant disruption to traffic or for contractor and public health and safety reasons (e.g. for sewer connections when flow is typically lower (at night) to limit risk of overflows, or in areas where excavations cannot be left open and is not practicable to temporarily fill in) or for environmental reasons (e.g. to enable critical construction works in relation to stream and groundwater levels due to the tide and a forecast of severe weather). Neighbours to the works will be advised in writing in advance and noise and vibration will be minimised as far as practical.
Modern wastewater treatment plants don’t produce any odour under normal operating conditions. The parts of the treatment plant that can be odorous will be covered and the air extracted and passed through a biofilter to treat the odour. The terminal pump station will be in a building and the air from this will also be extracted and passed through a biofilter to treat the odour. Contingency plans will be developed to deal with any adverse effects if there is a plant breakdown.
Beneficial reuse of treated wastewater
Reusing resources is good for the environment and Akaroa is short of water in summer so we’re looking at future options to reuse the treated wastewater for irrigation, flushing toilets and home gardening. A large area of relatively flat land would be required if most of the wastewater was to be irrigated to land, and there is a limited amount of suitable land near Akaroa. Nevertheless, we’re investigating options and Lincoln University are undertaking experiments on soil cores taken from Akaroa to determine how much treated wastewater could be sustainably irrigated in the future.
However, there would always need to be a discharge to the harbour during large storm events when flows to the treatment plant are at their highest, due to stormwater inflow and groundwater infiltration into the wastewater pipes. Council is working to reduce the inflow and infiltration, but this is an expensive exercise and experience elsewhere has shown that it is extremely difficult to eliminate entirely.
The whole project is estimated to cost about $30 million, including the new treatment plant, new harbour outfall, new terminal pump station and upgrades to the existing pump stations and pipeline that runs through Akaroa. The costs for the new wastewater plant will be spread over all Christchurch City Council ratepayers and there will be no targeted rates for Akaroa users. The Council does not have targeted wastewater rates for any areas.