Intervention Analysis on the Effect of Two Sewage Screening Plants on the BOD sub(5)Levels in the Hong Kong Victoria Harbour and Vicinity

Changes in marine water 5-d BOD levels in Victoria Harbour, Hong Kong, after construction of two sewage screening plants in the vicinity were tracked by means of intervention analysis. Analysis of data from 10 stations in the study area shows that the 5-d BOD levels at four of five stations near one sewage plant declined immediately after initial plant operations in 1990; reductions were in the 6.76-15.44% range. The 5-d BOD levels also declined in the 6.5-21.54% range at five stations near the second plant. Monitoring stations closest to the outfalls of the two plants showed the greatest declines in 5-d BOD relative to stations distant from the outfalls.