Exploration on Soil Corrosivity towards Buried Metallic Structures in Tansen Municipality Roadway Areas

The corrosivity of soil towards the buried structures depends upon physicochemical parameters of soil. An empirical corrosion rating model is done for six soil corrosivity parameters such as physical parameters (colour, smell, general texture and types of soil) and chemical parameters (moisture content, pH, resistivity, chloride and sulphate ions) for collected 45 soil samples from three different depths of 0.4 m, 0.8 m and 1.2 m below the ground level of Batasedanda – Tansen Buspark - Parvas roadway areas of Tansen Municipality for their corrosive nature towards the buried structures. The values of moisture content, pH, resistivity, chloride content and sulphate content ranged from 5.27 % to 21.83 %, 6.91 to 9.46, 6,958.54 Ohm.cm to 28,691.58 Ohm.cm, 28.942 ppm to 104.86 ppm and 72 ppm to 284 ppm respectively in this research work. The experimental results indicated that the soils could be rated as mildly corrosive to less-corrosive groups to the buried structures according to American Standards of Testing and Methods (ASTM). Based on the findings of the present studies, it is best to bury metallic pipelines in between 0.4 m to 0.8 m but it can be done at 0.4 m if the soil is undisturbed. A polyethylene-sheet encasement around the galvanized-steel and cast-iron water pipelines or the use of non-conducting materials of gravel/ sand around the burying ground could be sufficient for the extension of their life up to 50 years or more. Present findings would be insightful and suggestive in making the corrosive land maps of the selected studied areas which would be helpful for the potable water pipeline works in municipal water supply system in Palpa, Nepal.