Alternative Measures of Sewage Treatment Works Dry Weather Flow
The current definition of sewage treatment works Dry Weather Flow (DWF) gives results with high year-on-year variability and cannot be calculated for a large proportion of data sets.
A wide range of alternatives are assessed against agreed selection criteria using over 3,000 works-years of validated flow data and nearly 2,000 works-years of associated rainfall data. A number are found to perform significantly better than the current definition, with percentile methods giving the best overall performance, and the 20th percentile of daily flows agreeing well on average with the summer DWF calculated by the existing method.
The implications of a change in definition have been assessed with regard to a wide range of issues, including consent compliance, funding via the Price Review, other consented flow parameters, and design.
The report provides a sound analytical basis for discussion and agreement between companies and regulators as to the preferred future approach.
|UKWIR Reference :- 05/WW/21/6||Published Date :- 14/07/2005|
|Retail Price (£) :- 80||ISBN :- 1 84057 496 8|