Raw water is diverted from the Nueces River and treated at the O. N. Stevens Water Treatment Plant located in the Five Points area of the City. The plant was initially constructed in 1954 and has a rated capacity of producing up to 167 million gallons a day. On average, the plant produces 80 million gallons of water, which is equivalent to 40 miles of railroad tanks cars. How is Water Treated? (click to see diagram) Pre-treatment stage: Raw water is pumped from Nueces River and Lake Texana (via the Mary Rhodes Pipeline) through screens that remove leaves, sticks, fish, and other large debris. Once the raw water arrives at the water treatment plant, potassium permanganate is added to remove algae and reduce the odor of the water. Chlorine and ammonium sulfate are added to form chloramines and begin the disinfection process. The amount of water treated and the detention time in the primary and secondary settling basins will dictate the dosage level of the chlorine. Coagulant and coagulant aid (aluminum sulfate and polymer), are added to begin the particle removal process. The dosage level of the coagulant is determined by the level of particles in the raw water. Rain events will cause the particle levels to increase and will require higher dosages of the coagulant to clean the water. By the time the water in process reaches the end of the settling basins, 100% of the disinfection process is complete and approximately 95% of the particle removal is complete. |
