A 76,000 m3/d direct .filtration plant is applyiJ!g free chlorine as a disinfectant at a dose of 2.0 mg/L. Their low flow is 19,000 m3/d. Their water analysis is the same as that for Crater Lake (Problem 13-24). To save money, they would like to reduce the chlorine dose at low flow. The trn of their contact chamber is 27 .5 minutes under peak flow conditions (pH = 7 .0 and 5°C). Check the plant operation to confirm that they are meeting the L T2ESWTR disinfection requirements, and determine what dose they should use at low flow.