16. Waste Volume One There are currently a large number of discharges to land in Marlborough and this will only increase in the future given the ongoing regional growth and preference for discharges to land as opposed to water. It seems sensible to utilise the land resource to treat liquid wastes in Marlborough, but it is essential that discharges to land are well managed as they could, in isolation or in combination, give rise to adverse effects of similar magnitude or greater than those caused by discharges to water. [RPS] Objective 16.3 – The discharge of liquid wastes onto or into land is managed in a way that avoids adverse effects on water and soil quality, land and water ecosystems, slope stability and cultural and amenity values. The water quality provisions of the MEP encourage the discharge of contaminants to land in preference to water. This policy position recognises that we live in an environment well suited to using soil as a treatment medium. However, it is possible for discharges to land to adversely affect soil quality and the surrounding environment. Consistent with other provisions in the MEP, the objective seeks to avoid such adverse effects. This can be achieved by carefully designing, constructing, managing and maintaining systems for the discharge of liquid waste to land so that they reflect environmental constraints. [RPS, R] Policy 16.3.1 – Ensure that wastewater management systems are designed, located and installed to effectively treat and/or contain the contaminants present in wastewater. It is important that the discharge of contaminants onto or into land is undertaken in a manner compatible with the ability of the land resource to treat and/or contain contaminants present in the wastewater. If this is not achieved, the discharge will adversely affect the immediate and surrounding environment. This policy targets the critical role that wastewater management system designers and installers have in avoiding the potential for adverse effects. It is essential that the design of any wastewater management system recognises and provides for the characteristics and constraints of the site (especially the area to be used as a land application area) and that the system is installed according to the design. [RPS, R] Policy 16.3.2 – Require discharge permits for the discharge of contaminants onto or into land where there are significant environmental constraints to effective wastewater management. Chapter 15 - Resource Quality (Water, Air, Soil) encourages the discharge of contaminants to land in preference to water. This is achieved through permitted activity rules. However, not all Marlborough soils are well suited to receiving and treating contaminants present in wastewater. Of particular note are: • Soils in the Marlborough Sounds. These soils tend to have a high proportion of clay and corresponding low permeability rates. Furthermore, in many areas the soil is also of inadequate depth to provide sufficient treatment of bacteria and the underlying geology can be prone to instability. • The gravel/sand soils on the coastal margin of Cloudy Bay, which have extremely high permeability, limited ability to provide treatment/containment of bacteria and nutrients and a high groundwater table. • The poorly drained soils of the Lower Wairau Plain, which because of low permeability rates are prone to ponding wastewater. • The loess hills soils to the south of the Wairau Plain have a high potential for tunnel gully erosion. • Any land in close proximity to surface water bodies has the potential for runoff and surface water contamination. 16 – 10