12VAC5-590-1090: Plant storage

A. Backwash water storage tanks shall be sized in conjunction with available pump units and finished water storage to provide the filter backwash water required. Consideration shall be given to the possibility of having to wash more than one filter at a time or several filters in succession.

B. Clearwell storage shall be sized, in conjunction with distribution system storage, to relieve the filters from having to follow fluctuations in water use or meet peak demands, including filter backwash water. When finished water storage is used to provide proper contact time for disinfection, special attention shall be given to size, drawdown, and baffling. Plant clearwells shall be equipped with a raised viewing port having a clear glass or plastic viewing window and a submerged, waterproofed electric light.

C. Finished water shall not be stored or conveyed in a compartment adjacent to nonpotable water when the two compartments are separated by a single wall.

D. Receiving basins and pump wet wells for finished water shall be designed as finished water storage structures.