STUDY OF ROOT INVASION OF SEWER PIPES AND POTENTIAL AMELIORATIVE TECHNIQUES
The invasion of sewer pipes by tree roots is a major cost to both the corporations managing urban infrastructure and to private landowners. There are a number of factors that may result in the growth of roots into and around the pipes. These include pipe material factors such as degradation of aging pipes and damage caused to pipes and environmental factors such as site conditions, tree proximity and tree species. Research into these issues will help in developing more efficient methods of controlling root invasion, benefiting both the management of sewer flow and the urban landscape. A study of root invasions in suburban Melbourne was carried out to examine relationships between site factors and root blockages. Common factors found associated with tree root blockages were Eucalyptus and Melaleuca species over 4m high within 6 m of sewers, pipe depth 2 m or less, rubber ring joined 150 mm diameter vitreous clay, 30 to 60 years old, soil types with sandy topsoils, and blockages occurring most frequently when temperatures and evaporation were at their lowest i.e. August to October. An experiment was conducted to evaluate chemical and physical treatments for preventing root growth in disturbed soil with high nutrient content and readily available moisture (modeling leaking sewers). Over a period of 177 days significant inhibition was achieved with the chemical treatments dichlobenil (278 g/m3 and 1392 g/m3), copper sulphate (1.5 g Cu/kg soil and 7.5 gCu/kg soil), oryzalin (1031 g/m3) and trifluralin (260 g/m3) and the physical treatments slaked lime (ratio of 10 soil:1 lime and 10 soil:5 lime) and cement slurry. The potential for the use of these treatments in areas where tree roots have damaged sewers is discussed.
Pohls, O., Bailey, N.G. and May, P.B. (2004). STUDY OF ROOT INVASION OF SEWER PIPES AND POTENTIAL AMELIORATIVE TECHNIQUES. Acta Hortic. 643, 113-121
Eucalyptus, Melaleuca, dichlobenil, copper sulphate, oryzalin, trifluralin, sandy soil.