Marlborough Sounds Resource Management Plan 10 March 2006 The residential properties in these areas are the result of historic subdivision practices. These communities are not serviced by reticulated sewerage systems and the process used to approve the subdivision of land often did not take into account the land area required for the effective on-site management of domestic wastewater. As a result, many of the on-site wastewater management systems installed to service residential buildings were inappropriate given the site conditions. For example, soak pits were commonly installed (in soils of low permeability) to service older residential developments. Many of the on-site systems initially installed in these communities have either subsequently failed, and have had to be upgraded or replaced, or continue to perform in a less than satisfactory manner. This is reflected in the results of water quality and shellfish monitoring, which show contamination of coastal waters. Additionally, complaints have been made about offensive and objectionable odour and the runoff of domestic wastewater onto neighbouring properties. Given the residential character of these communities, there may also be an increased risk of people coming into contact with untreated or partially treated sewage. The nature and extent of the effects on the surrounding environment and on public health need to be accurately assessed. It may be established that these communities are unsustainable in the absence of a community sewerage system. 14.5(b) Issue The subdivision of unsewered land for residential use can create a development density that exceeds the capacity of individual allotments to assimilate domestic wastewater in a manner that protects the surrounding environment. There is a demand for further residential properties in the Marlborough Sounds, and the Council continually receives applications for resource consent to subdivide land, currently zoned either Sounds Residential or Rural One, for residential purposes. In the absence of reticulated sewerage, all of the newly created allotments are serviced by on-site wastewater management systems. However, on-site systems may not necessarily be the most appropriate means of servicing the subdivision due to the site conditions, and even where they are, if the development does not take into account the land area required for the effective on-site management of domestic wastewater, the resultant properties could be too small for this purpose. Where the density of development is such that multiple residential buildings are unable to treat and contain the domestic wastewater on-site, the adverse effects identified in Issue 14.5(a) can result. In this manner, additional subdivision and development can exacerbate existing problems or can create further communities that are unsustainable in terms of on-site management of domestic wastewater. 14 - 18