Water Treatment Facility Tour
The City of Buffalo retained Bolton & Menk, Inc. to study the existing water system, both in terms of meeting existing needs and the demands of projected growth. The results of the study were summarized in a “Water System Study and Report”.
One of the conclusions of the water system study was that the existing water treatment facility is approaching 20 years old. The existing treatment facility has to operate at the maximum capacity to meet the current water demands, and would need to be increased in order to meet the projected 20 year demands. The supply of treated water must grow in order to continue to serve the City of Buffalo’s resident’s and businesses.
Therefore, various water treatment alternatives were evaluated. The recommended alternative was to construct a new treatment plant in conjunction with remodeling the existing treatment plant, thus maximizing the investment in the original treatment facility.
The Buffalo Water Treatment Facility has an average design capacity of 3.2 million gallons per day and a maximum capacity of 7.9 million gallons per day. The first step in the water treatment process is aeration. The purpose of aeration is to enhance the oxidation of iron and manganese to an insoluble form so that it can be filtered from the water. The water is pumped from the existing municipal well to the top of the aerator. The aerator is comprised of numerous slotted trays through which the water flows. A forced draft fan blows air through the aerator to further aid in the oxidation process.
From the aerator, the water flows by gravity into a 120,730 gallon detention tank which holds the water for approximately 55 minutes. The detention tank allows for further oxidation of the iron and manganese. The chemical potassium Permanganate is added to the detention tank to assist in the oxidization of manganese.
After the detention tank, the water flows by gravity into seven new and four refurbished filter basins. Each filter basin has a Leopold Type S underdrain system and dual filter media. The underdrain system is comprised of approximately 11-inch wide by 12 1/2-inch high by 48-inch long blocks made of high density polyethylene (HDPE). The blocks are arranged end to end and mechanically joined to form continuous underdrain laterals for the full length of the filter. An integral media support (IMS) cap is placed on top of the underdrain blocks to retain filter media. The filter media itself is composed of 18 inches of anthracite and 12 inches of specially graded crushed silica sand. The anthracite and silica sand filter out the iron and manganese which were oxidized to an insoluble form in the previous stages.
The material which is trapped by the filter beds is removed from the filters by a process called backwashing. Bach washing is accomplished by means of reversing the flow of the water through the filter. This process is further enhanced by blowing compressed air up through the underdrain blocks. The backwash water flows into reclaim tanks. The backwash reclaim tanks are located underground, adjacent to the treatment plant, and have a capacity of 193,000 gallons. The backwash water is held in the tanks, once again allowing particulates to settle out. The clear water is then returned to the beginning of the process and the accumulated solids are pumped through the sanitary sewer system to the City’s wastewater treatment facility.
The filtered water flows by gravity to a new 510,000 gallon and existing 700,000 gallon clearwell/reservoirs, both of which are located under the main floor of the facility. Five 75-horsepower vertical turbine pumps are mounted on top of the clearwell. These pumps distribute water into the City’s water distribution system. Before leaving the plant, the water is chlorinated to provide a disinfecting residual throughout the system and fluoridated to enhance public dental health.
The operation of the wells, the treatment plant and the high service pumps is automatically controlled by Allen Bradley Programmable Logic Controllers (PLC’s ). The IBM compatible PC SCADA system using Wonderware software enables the operator to run the treatment plant directly from the control room. All alarm conditions are printed out in the control room and all critical alarms are sent out electronically to the duty operator.