Project: Installation of a complete new wastewater treatment solution to an existing 4 bedroom property in Clare, Ireland.
System: BIOROCK ECOROCK-2000 System discharging to a small footprint polishing filter. (See site assessment below)
The house is a 1980's construction 4 bedroom house with a figure 8 septic tank discharging to very wet ground with poor permeability. The septic tank was being emptied every 2-3 months and was regularly causing blockages in the drains. As the owner was living overseas and renting the property he wanted a solution which complied with EPA and County Council requirements, minimal maintenance and a company that would project manage all aspects of the installation.
The in-situ soils /subsoils were tested for percolation and were found to have low permeability with a T/ P value of > 90. The surface drainage network in the area ultimately drains to the south towards the Shannon river. As there was an existing system on-site and having regard to the provisions in Section 6.6 of EPA 2009 the optimum solution for the site was to install a proprietary secondary treatment system and polishing filter. Selection of a BIOROCK system with a high effluent quality standard enabled the use of a polishing filter with a high hydraulic loading rate and small footprint.
This would eliminate ponding of poorly treated effluent in the garden, and ensure forward flow through the system eliminating blockages in the sewer from the house. As the soils on site were not suitable for use in a soil polishing filter the most cost effective option was a constructed wetland polishing system. A raised Vertical flow Gravel Reed bed polishing filter was recommended with a maximum hydraulic loading rate of 100litres/m2/day, designed in accordance with EPA 2009 and SR CEN/TR 12566-5: 2008 for tertiary effluent polishing.
It was proposed to provide a 300mm deep gravel distribution layer (10-30mm pea gravel) with an area of 70m2, configured in an area measuring 8.0m x 8.75m.
The 9m2 Reed bed was sited centrally over the gravel percolation.
The installed BIOROCK ECOROCK-2000 System complies fully with the EN12566-3 standard and the new SR66 Irish Standard for treatment plants for up to 10 persons.