Lined zero-discharge facilities have the following security distances to:
Drilled drinking water exploitation or well for 1-10 households, 30 meters
Drilled drinking water exploitation or well for more than 10 households, 50 m
Distance to rivers and lakes, drainage systems, 5 m
Distance to property border 2 m
Distance – vertical – to ground water 0 m
Distance to groundwater protection area class 1 and 2, 0 m since the system is waterproof and zero-discharge.
The site where the facility is built needs to have such a consistency of the ground that digging the basin to a depth of 1,5 meters will be possible. The ground water level on the site does not substantially affect the building or functioning of the willow purification system as it is closed from the surroundings by the basin. However, the site must not get flooded during wet periods by nearby river/lakes, heavy rain or meltwater. It is best to choose a site that is somewhat higher than the surrounding area, so that flooding is not possible. The basin rim needs to be at the same height all around and the basin needs to be horizontal, so the location needs to be relatively flat so that it will be possible to even out the ground for the basin.
The zero-discharge willow facility basin can be built all year round. However, dryer periods are best for the digging work. It is recommended to build the basin in the summer or autumn and prepare it for planting the willow in the spring. The willow plants always need to be planted in early spring, end of April to beginning of May. In this way, the willow trees will grow up and empty the soil during spring summer and autumn so that there will be sufficient room in the soil for wastewater and rain falling directly in the facility during the winter.
In Finland a waste water treatment system always needs a permit from the municipality so a “Jätevesiselvitys” needs to be done. At least 2 months should be reserved for the planning and permit process as the normal time to get a building permit is from two to six weeks.
A zero-discharge willow purification facility is simple to maintain. The maintenance of the facility is done once a year in the spring before the willow grows new leaves. It is recommended to empty the settling tank once a year. The system is flushed with clean water to prevent clogging of the waste water distribution pipes. A portion of willow trees are cut and the wood material can be used as fuel or as garden mulch for soil improvement.