St. Bernard Parish New Water Treatment Plant
BKI was selected by St. Bernard Parish to design a new 12 MGD water treatment plant. Along with the Department of Public Works, BKI investigated several design alternatives and selected a cost-effective treatment process. BKI then prepared a General Design Memorandum to further define the basis for engineering design, to evaluate operation and maintenance requirements, and to determine how to build a new treatment facility on the existing plant site while maintaining efficient operation of the existing treatment plant.
The plant as constructed has three up-flow clarifiers of 435,000 gallons each that provide the initial solids removal for the raw water from the Mississippi River. Polymer and lime are injected prior to the clarifiers to aid in coagulation. The clarified water is then sent to six rapid sand filters for final treatment. Each of the sand filters is equipped with air-assisted cleaning to shorten the time required for backwash and to aid in resettling the filter media. The clarifier and filter equipment was manufactured and supplied by Tonka Water of Plymouth, MN.
A clearwell pump station was constructed to pump the treated water to the existing 10 MG and 3 MG ground storage tanks on the existing plant site. This pump station is also able to provide the water required to backflush the sand filters when required during the normal treatment process.
A separate filter waste pump station was constructed to transfer the flow from the filter backwash process to the existing backwash tank at the original Plant No. 1 near the East St. Bernard Hwy. side of the water plant site. The pumps in this existing tank were upsized to handle the additional flow from the new plant and return the collected filter sediment to the river.
As part of the plant, BKI designed a new control/filter building. This building houses the pipe gallery and sand filters on the first floor and the control building and plant offices on the second floor. A chemical building was also constructed to contain all of the chemical processed necessary for plant operation including the chlorine room, polymer room, alum tanks and feed pumps, and the ammonia storage and feed system. Both the control/filter building and the chemical building were designed to withstand sustained winds up to 130 MPH. All of the mechanical equipment for this project is located above the base flood elevation for the plant site to minimize any future flood related damages.
Existing high service pumps that supply water to the distribution system were kept in service from the existing Plants 1 and 2, which were rebuilt after Hurricane Katrina.
The project cost for this water plant was $23,500,000. It was constructed under budget, despite numerous substantial changes made at the owner’s request during construction.
