Soil hydraulic characteristics and its influence on the design of soak-away systems at obinze, southeast Nigeria

Abstract

The hydraulic characteristics of the soil profile in a plot of land designated for a residential purpose were studied to obtain dependable data for the design of efficient septic- soak-away system in the estate. In situ infiltration tests on three horizons above 400 cm depth were conducted, and soil samples taken from the same locations for soil classification and hydraulic inductivity tests. The soils were classified as silt loam, clay and silty sand for the three horizons respectively from the surface downwards. The average infiltration rates and cumulative infiltrations were found to be correspondingly 18.36 m/hr and 36.71 mm; 8.87 mm/hr and 31.48 mm; 28.84 mm/h and 49.68 mm. The average hydraulic conductivity values were 6.49x10-1 mm/hr, 4.32x 10-1 mm/hr and 9.36x10-1mm/hr respectively. These results indicate that there might be delayed flow between the upper and lower horizons. This information would be invaluable in the design of the septic and soak-away chambers in terms of depth and size.

Keywords: Soak-away system, hydraulic conductivity, flow case, pit chambers