On-site Effluent Disposal

This is one of the most important issues facing rural planners today. Although it effects all ares, it is mainly a problem for urban rural residential developments. There are two main issues - the amount of land needed to dispose of the effluent and the failure of the systems themselves. Although rather simple in broad terns, it is a very complex matter when trying to find a solution. Although it is the responsibility of the State Government to set policy and direction, this has not been forthcoming. There has been no overall coordination or guidance from the State Government on the issue of effluent disposal both from a single on-site perspective or from an overall catchment perspective concerning impact on the waterways of the State. It has been left to local government to develop guidelines to ensure that the effluent disposal is adequate for dwellings. It must be remembered, however, that effluent disposal is only one of the impacts on water quality and that we should consider the whole water cycle and its sources of pollution.

The issue is more of a problem in urban areas where it has been well documented that land less than 1000 square metrs is not large enough to adequately dispose of irrigated effluent becaus of soil and climatic limitations (in fact, depending on the soil and climate, larger lots of 4000 square metres and larger may also not be suitable). In these situations a reticulated system is usually installed. However, these are extremely expensive ($70 million for 4500 dwelllings). It might come as a surprise to some metropolitan colleagues that there are a significant number of towns and villages throughout NSW (including some within 150 km of the Sydney CBD with populations of 3000) that are not connected to a reticulated sewage system which is the norm in nearly all of metropolitan Sydney. These unsewered towns and villages rely on a combination of on-site disposal and pumpout systems. The on-site disposal systems are either the septic tank with absorption pits or aerated wastewater treatment systems (AWTS) that irrigate the effluent over the lawn or garden bed.

In addition to the size of the irrigation area, other problems relate to the operation and maintenance of the disposal system and also to the siting of the system and the irrigation area, both of which are sometimes installed in inappropriate locations. There are three results:

• damp backyards which can constitute a health hazard;
• overland flow of the nutrient rich effluent onto other properties and / or directly into the surrounding river system; and
• potential contamination of groundwater.

It must be pointed out, that contrary to most people's understanging,, the effluent that is irrigated is high in nutrients - nitrogen and phosphorous. Let us not forget that it is the high nutrient content of the effluent that contributes to the algal blooms that occur with increasing frequency in our major river systems.

It has been stated that there has not been a coordinated State Government approach to the management and operation of on-site effluent disposal systems for domestic households. This is backed up by the Draft Report of the Public Inquiry into the Management of Sewage and Sewage By-products in the NSW Coastal Zone (August 1997). The Hawkesbury Nepean Catchment Management Trust has produced a discussion paper on Domestic On-site Sewage Storage, Treatment and Disposal (August 1995). A number of Councils have prepared documents ranging from Studies to DCP's. But the Government has been silent.

In February 1996, the State Government attempted to address this lack of standardised guidelines by releasing the draft "Environmental and Health Protection Guidelines for On-site Wastewater Management Systems for Domestic Households". This was a guideline for Local Government to use in the assessment of domestic wastewater treatment systems including both the DA and rezoning processes. Although being a standard guideline for application across the state, they did not take into account the need for a catchment wide approach to the issue. This is highlighted by the Sewage Inquiry mentioned above. The final guidelines are due for release in November but at the time of writing were not available. Information from the Department of Local Government has revealed that the new guidelines do place emphasis on catchment planning and that there will be a requirement for Councils to produce On-site Sewage Management Plans as part of the Management Plans required by the Local Government Act. The guidelines also place emphasis on the methodology for determining adequate irrigation areas instead of stipulating a minimum as the draft did. The methodology outlined can be used for rezonings as well as the DA/BA process. To ensure that they are adequately addressed in the rezoning process, however, it makes sense of them to be a section 117 Direction. It is noted that this matter has been overlooked by the DUAP in the review of the section 117 directions recently released. It is hoped that the matter will be addressed before they are finalised.

It is hoped that with standardised guidelines and improved communication between State and Local Government that the issue of on-site effluent disposal can be addressed in a better manner than it has up to now.

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