Marlborough Sounds Resource Management Plan 10 M arch 2006 • On-site cluster systems (applying on-site technology to service two or more dwellings); • Cluster systems (also serving two or more dwellings, but where the subsequent discharge is to an off-site environment); and • Full community sewerage schemes. The best practicable option can then be determined having regard to: • The sensitivity of the receiving environment; • The financial implications, and the effects on the environment, of each option when compared with the other options; and • The current state of technical knowledge and the likelihood that each option can be successfully applied. (Policies 14.4.1.1.3 to 14.4.1.1.9 are also all relevant to such an assessment.) If the best practicable option is an on-site option, it is still important that the actual size and configuration of the allotments allows for effective land treatment areas to be developed. This must include reserve areas to safeguard against unanticipated problems or future failure of the land application area. Soil and other site conditions can also vary across each of the proposed allotments, so the land treatment area and reserve area must be located on the most suitable soils and topography for on-site management of domestic wastewater. The Council will provide guidance on how these areas can be determined. In this manner, Policies 14.5.1.1 to 14.5.1.3 will assist to achieve a density of development that is consistent with the capacity of the surrounding environment to assimilate domestic wastewater. In most cases it will not be possible to apply for the discharge permits required for each of the allotments at the same stage as the subdivision consent. This is because the nature of the dwellings to be built upon the allotment, the resultant wastewater loading and therefore the size of the land treatment area are not known. None-the-less, the applicant will still need to demonstrate that a dwelling is capable of being serviced on each of the proposed allotments. In some cases, past subdivision of land has already created a development density that is not sustainable in the absence of some kind of community sewerage system. This is considered to have occurred in Okiwi Bay and Ngakuta Bay, where allotment sizes are typically between 800 and 1000 square metres. Water quality and shellfish monitoring has demonstrated that domestic wastewater discharges are probably not being contained within these allotments. There is still a substantial area of land zoned Sounds Residential that is yet to be subdivided into residential allotments in these two bays. It is considered to be inappropriate to allow for further residential allotments of a similar character to those that already exist, when the existing level of development is already adversely affecting the surrounding environment. The Council also needs to establish whether past residential subdivision and development is now adversely affecting coastal water quality, soil quality, land stability or residential amenity values elsewhere in the Marlborough Sounds. 14 - 20