Estimating the length of sections of saline groundwater infiltration into sewage pipes for use of treated wastewater as irrigation water
2009
Yamashita, T., National Inst. for Rural Engineering, Tsukuba, Ibaraki (Japan) | Shiozawa, S.
In the Shimajiri District of Okinawa, a project is underway to reuse treated wastewater as irrigation water. However, chloride ion concentration in treated wastewater is high here due to the infiltration of saline groundwater from damaged sewage pipes that are laid below sea level. It is thought that lowering this concentration will require rehabilitation of sewage pipes to prevent infiltration of saline groundwater. To incorporate such rehabilitation into agricultural land improvement projects and other undertakings, it will be necessary to ascertain the total length of sections in which saline groundwater infiltrates sewage pipes. In this study, we first clarified the concentration and flow rate of chloride ion in wastewater through measurements taken at manholes and other locations at which the possibility of saline groundwater infiltration exists. We then identified the length of a saline groundwater infiltration section within a typical extent in which such infiltration occurs, and then estimated the entire length of the infiltration section based on ratios of infiltration amount. We further considered methods for estimating the lengths of saline groundwater infiltration sections that would be applicable for general use.
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