Your Questions Answered - Waste water options under review
The Mangawhai Community Waste Water Scheme Advisory Panel tabled their recommendations to Council in July last year. Since that time staff and other experts have been hard at work further testing the recommendations and looking to see how they can implement them – in intent if not exactly.
Several initiatives are underway to attend to the matters of concern that the Panel raised.
Testing water quality in the harbour
A group is working with Council made up from community volunteers, Te Uri o Hau Settlement Trust and Northland Regional Council, who are assessing the current water quality. Water testing will take place at five selected test sites. This testing will assist in identifying issues affecting harbour water quality, and this will enable informed remedial actions to be taken both in the harbour and on the surrounding lands.
Preventing potential leakage from on-site septic tanks
The Mangawhai drainage district, which the wastewater scheme was designed to service, does not cover all the areas from where there is runoff into the harbour. Septic tanks service these areas, as they do still for some properties within the drainage district.
One of the recommendations from the Advisory Panel was that Council passes a bylaw requiring an independent inspection and maintenance certification for all on-site septic tank systems. The Council now has drafted a bylaw that requires all septic tanks that are within 300m of the coast, and/or are in urban areas with smaller plot sizes, to pass a “warrant of fitness.” This bylaw has been released for public consultation.
Disposal of treated wastewater from the plant to the farm
The panel recommended that primary disposal for the next 5-10 years should be through the expansion of irrigation on the existing Brown’s Road farm – with a minimum of 5-10 hectares of irrigation added to the farm within five years, and potentially a further 20 hectares, if required. Council has engaged a specialist consulting engineer to identify additional areas of the farm that could be utilised for disposal of the treated wastewater, and to identify areas of the farm not required. The Tracks Trust has indicated a desire to develop walking tracks in any bush areas on the farm not needed for disposal.
Council has identified that the farm has capacity for over 15 years at current growth rates if we extend reticulation for disposal. In the future the Mangawhai Golf Course may be needed and work will continue to see if this is realistic. The decision on this is not needed for some time.
Wastewater treatment plant capacity
When the treatment plant was built, the specifications were for a peak capacity flow of 1,380 cubic metres per day. This flow is expected to be reached by 2025 when further investment will be needed. The main pressure point in the plant’s capacity is a few days over New Year. This year we will be testing ways to manage this peak so that the capacity of the plant is sufficient for many more years to come.
The plant was also designed to provide treated water of a quality suitable for irrigating a dairy farm, as was the use of the Browns Road farm at the time of purchase. This quality is not required for normal disposal and should be able to be reduced, for the farm is no longer used for dairying. A revised resource consent application to Northland Regional Council is being developed that requests approval to treat the wastewater to a standard still absolutely safe for land disposal. If the consent variation is successful, it will extend the current capacity of the plant beyond 2025.