ABSTRACTAn 84 m (276 ft) by 64 m (205 ft) experimental leaching bed was constructed to receive the secondary effluent from the Norwood, Ontario sewage treatment plant. The distribution system consisted of 100 mm diameter perforated pipes laid 2.1 m apart in 0.45 m wide trenches. The main soil layer at the test site was sandy silt. Ground‐water levels at the site were measured approximately weekly at 36 piezometers for a period of about 2½ years. An initial hydraulic loading of 122,700 1/day caused surface ponding. A reduced loading of 40,900 1/day was then used for most of the study period. Ground‐water level fluctuations beneath and adjacent to the leaching bed were attributed to seasonally varying infiltration and hydraulic loading. The experimental data were simulated using a transient two‐dimensional, phreatic integrated depth finite‐element model and an analytic solution for ground‐water mounding. Results from the study indicated that seasonal infiltration was a controlling factor in determining leaching bed design loads. Both mathematical models were found adequate
展开▼
