Septic Tank Effluent Drainage System (STEDS)

Kiltillane, Templemore, Co Tipperary

As part of a programme to evaluate new technologies for providing cost-effective and efficient waste-water collection and treatment for small rural villages, a Septic Tank Effluent Drainage System (STEDS) was installed at Kiltillane, Templemore, Co Tipperary. This is the first time this technology will be used in Ireland.The project was co-ordinated by North Tipperary County Council and the system was installed in the 30 house community of Kiltillane on the outskirts of Templemore.

The Septic Tank Effluent Discharge Systems (STEDS) project originated from a Water Services National Training Group trip to Norway to explore the design and construction of STEDS. This system allows the septic tank to remain in use while collecting the effluent that might otherwise lead to pollution of water courses or give rise to nuisance and odour problems locally. This alternative collection/treatment system is considered appropriate for use in small rural communities with low population density and site specific environmental conditions such as shallow bedrock, high groundwater conditions and limited effluent discharge locations. Such alternative wastewater collection and treatment systems have been used in the United States for over 20 years.

The objective of this project is to test the STEDS system under Irish conditions and, based on the lessons learned, to give widespread application to this innovative and cost effective approach to meeting the wastewater collection and treatment needs of small rural communities.

Under the STEDS approach the septic tank is kept on the householders’ property. The effluent is then collected for subsequent treatment and disposal. Raw sewage flows from the house to a watertight underground interceptor tank, where it is pre-treated. Suspended solids remain in the interceptor tank (within the boundary of the property) for passive natural treatment and require de-sludging only once every 10 to 12 years. Only the filtered liquid is discharged (by either pump or gravity) through small bore collection lines to a central treatment system. The filtered effluent is treated in low cost, low maintenance recirculating filters that utilise packed bed technology.

The STEDS system was built to the highest standard and under the direct supervision of the American manufacturers of the system, Orenco Systems Inc., Oregon. The completed plant is operated by way of a 20-year operation and maintenance contract by Orenco’s agent in Ireland, EPS Ltd, Mallow, Co Cork.

Substantial construction cost savings result with up to a 50% reduction in treatment plants sizes. The STEDS system also has low operating and maintenance costs, with running costs approximately 25% of normal activated sludge systems. Final effluent standard is superior to that produced by conventional treatment systems.