Allison Wastewater Treatment Plant

The Allison Treatment Plant serves the northwest side of the city and is located close to the Nueces River. The plant first started treating wastewater in 1966. Initially, the treatment capacity was 2.0 million gallons per day (MGD). Over the years, it has been expanded twice: In 1983 and in 1985 when the capacity was increased to treat 5.0 MGD. The service area of the plant is about 5,600 acres. Two major trunk mains feed into the plant, one from the Calallen area and the second one from the Tuloso area. The plant receives 18 percent of its flow from a meat packing plant.

The Allison Plant presently treats about 2.7 MGD. The plant is permitted to discharge treated wastewater with a 20 milligrams per liter (mg/l) BOD5 and 20 mg/l TSS quality. The effluent averages 4 mg/l BOD5 and 6 mg/l TSS. The plant provides reuse water for irrigation of the Coastal Bend State Veterans Cemetery. This plant has received gold and silver awards for peak performance since 1989. These awards are from the National Association of Clean Water Agencies.

The plant is an activated sludge process plant operated in a plug flow mode. Excess biosolids are drawn out of the secondary clarifiers, then thickened prior to digestion. The biosolids are dewatered using two belt filter presses and the resulting cake, which is usually in the range of 13 to 15 percent solids, is transferred to the sanitary landfill. About 3.5 tons of biosolids per day are processed at this plant. This facility operates under an authorized permit issued by Texas Commission on Environmental Quality.

The Allison Plant has a staff of ten people and is staffed seven days a week. The coordinator has a Class A Wastewater Operator's Certificate issued by TCEQ. The operators have a Class B or Class C Wastewater Operator's Certificates.