Section 58.01.08.524 - SURFACE WATER TREATMENT: DIRECT FILTRATIONDirect filtration, as used herein, refers to the filtration of a surface water following chemical coagulation and possibly flocculation but without prior settling. The nature of the treatment process will depend upon the raw water quality. A full scale direct filtration plant must not be constructed without prior pilot studies which are acceptable to the Department. In-plant demonstration studies are required where conventional treatment plants are converted to direct filtration. Where direct filtration is proposed, an engineering report must be submitted prior to conducting pilot plant or in-plant demonstration studies in accordance with Subsection 501.19.
01.Filtration Requirements. a. Filters must be rapid rate gravity filters with dual or mixed media. The final filter design must be based on the pilot plant or in-plant demonstration studies, and all portions of Section 518 apply. Pressure filters or single media sand filters will not be used.b. A continuous recording turbidimeter must be installed on each filter effluent line and on the composite filter effluent line.c. Additional continuous monitoring equipment such as particle counting or streaming current metering to assist in control of coagulant dose may be required by the Department.02.Siting Requirements. The plant design and land ownership surrounding the plant must allow for modifications of the plant.03.Redundancy. A minimum of two (2) units must be provided for filtration such that plant capacity can be maintained with any component out of service for maintenance or repairs.Idaho Admin. Code r. 58.01.08.524