Horner & Shifrin led the planning and preliminary design effort to modify or replace primary and secondary settling process trains and filters in an existing 217 mgd surface water treatment plant. Two basin alternatives were identified by the owner:
(1) construct trains C & D as planned by H&S in 1993 at 100 MGD finished water capacity
(2) Rehab basins 1,2,3,4, 5, 6, and 7 to create (4 was partially upgraded in 2008) treatment trains for four primary floc/ settling and two secondary floc settling steps to create 100 mgd finished water capacity.
The second alternative included replacing all existing flocculation equipment and installing new plus new circular solids removal rakes and drives. Study also includes an option to add new filters to replace existing Filter Plants 1 and 2 or rehab existing filter building and floc basins. In addition, owner has proposed that new sodium hypochlorite bulk tank facility with day tanks and metering pumps per AWC T2 standards to replace existing gas chlorination system.
St Louis, Missouri