10 March 2006 Chapter 14 - Discharges of Waste to Land A high proportion of existing residential buildings are serviced by conventional on- site systems, comprising a septic tank and some form of a land application area (usually a soak pit or trenches). However, advanced on-site systems are increasingly being used to treat the wastewater to a secondary standard before it is discharged into or onto land within the land application area. The operational and maintenance requirements of each system vary, from the pumping out of septic tanks at approximately five year intervals, through to the regular inspections (undertaken by trained technicians) required for some advanced on- site systems. Whichever system is used, it will not perform in an efficient operating condition unless appropriate maintenance is undertaken regularly. A lack of maintenance increases the risk of system failure and creates the potential for adverse effects on the surrounding environment. The extent to which existing discharges of domestic wastewater from on-site systems are adversely affecting the Marlborough Sounds environment is not certain. It is difficult to monitor such effects, due to a lack of knowledge about existing on-site systems, the intermittent nature of occupancy, the isolated nature of much of the Marlborough Sounds, variable weather and tides, “natural” sources of contaminants and the extent of coastal waters. 14.4.1 Objective and Policies Objective 1 To ensure that new on-site wastewater management systems are designed, located and installed to effectively treat and contain all domestic wastewater on-site. Policy 1.1 To require discharge permits for all new on-site domestic wastewater discharges. Policy 1.2 To approve discharge permit applications for new on-site domestic wastewater discharges where: (a) There is no public sewer located within 30 metres of the lot boundary or within 60 metres of the closest building on the lot; (b) The on-site wastewater management system will effectively service the building(s) to which it is connected; (c) The land application area is located as far as practical from any surface waterbody or coastal water; (d) The discharge will not contaminate surface water, coastal water or groundwater; (e) The discharge will not initiate instability, or make existing instability worse; (f) The discharge will not create offensive or objectionable odour or adversely affect the amenity values enjoyed on adjoining properties. Policy 1.3 All design flows (the volume of domestic wastewater to be discharged into or onto land) shall reflect the potential occupancy of the building(s) that the on-site wastewater management system serves. 14 - 9