The City of Hot Springs, Ark., wastewater treatment system serves 23,000 customers and requires the maintenance of more than 600 miles of gravity and force mains. With an eye toward implementing a more proactive maintenance program and addressing issues arising from capacity constraints and aging equipment, the city undertook a comprehensive overhaul of its municipal wastewater infrastructure, including a complete revamp of its Fairwood Lift Station.
The Cypress Creek wastewater treatment plant in Florence, Ala., uses an extended aeration activated sludge process with a design capacity of 20 mgd. Placed into service in 2001, the plant operates at an average daily rate of 10 to 15 mgd. A 40-acre aerated lagoon with an additional capacity of 30 mgd acts as an EQ basin, helping to address inflow and infiltration. Excess flows are contained and returned at a controlled rate to the plant for treatment.
The City of Reno, Nev., has long battled the buildup of fats oils, and grease in the wet wells of wastewater lift stations in the valleys within the high desert city. Recently, the city set out to address the problem and reduce the associated costs.
A city of 13,000, Auburn, Ind., operates an activated sludge secondary wastewater treatment facility. Located within commuting distance north of Fort Wayne, the municipal utility’s 6-sq-mile service area has historically experienced pronounced peak flows caused by nearly a quarter of its collection system consisting of combined storm water and sanitary sewer lines. Complicating matters, the system’s jet mixing pumps repeatedly clogged, resulting in costly maintenance and aggravated plant employees.
For almost 50 years, CPS Energy of San Antonio has drawn water from the San Antonio River to recharge Braunig and Calaveras lakes, which the utility built in the 1960s to provide cooling water for its power plants.
Raw water drawn from deep reservoirs or lakes can acquire undesirable taste and odor and elevated manganese issues, especially in autumn, when seasonal stratification and turnover allow decaying plant and organic residue to reach the lower-level hypolimnion and further deplete already limited oxygen.
Hidden Valley Lake is a lakeside residential development outside of Lawrenceville, Ind., in Dearborn County. Valley Rural Utilities Company (VRUC) acquired the Hidden Lake service area in 1995 from the homeowners’ association that had assumed control of the sewage system from the subdivision’s developer. The private utility serves a total of 1,945 customers in the service area and anticipates projected growth will add another 1,000 connections.
The Adams Field Wastewater Treatment Plant (WWTP) in Little Rock, Ark., receives wastewater from 63,000 homes and businesses. Designed in 1961 for primary treatment, the facility was rated at 36 mgd after the addition of secondary treatment in 1972. The plant now handles 70% of the sewage generated within the Little Rock Wastewater Utility service area.
Located in Dalarna in central Sweden, a wastewater pumping station has a Flygt pump NP3102 MT 464 and a competitor pump with a premium efficiency motor. The station was built in the early 1970s and today serves about 450 households. It connects to a 300- meter-long ø200-mm pipe, pumping wastewater from one side of a lake to the other, and has almost only friction losses.
Atlantic City (NJ) Sewerage Company (ACSC), a private utility with 7,500 connections in and around the “Boardwalk” casino district, keeps a keen eye trained on operating costs. Its focus until recently was on the excessive energy and maintenance expenses for three 300-hp long-shaft pumps at the Baltic Avenue Pump Station. The facility’s pumps were sized to handle the expected growth of the area’s casino industry.
Hurricane Sandy paralyzed LaGuardia Airport in New York as it rolled through the Northeast in October 2012. After the airport’s five storm water pump stations lost power, an estimated 100 million gallons of water built up to four feet deep at some points, including along the shuttle ramps of this busy hub.
Jackson Energy Authority serves nearly 40,000 residences, businesses and industrial customers in and around Jackson, Tenn.
Two aging 7.5-hp three-phase pumps in the utility’s Rolling Acres Lift Station were experiencing frequent outages that required increasing man-hours for maintenance and repair. The electric meter at the duplex station showed high power consumption resulting from recurring drag on the impellers. As these combined factors drained more and more of the utility’s budget, the increasing frequency of pump failures raised the risk of sanitary sewer overflows.
The Baltic Sea, the largest body of low-salinity water in the world, has a coastline shared by nine countries. As the drainage basin to 85 million people, the environmental strain on the sea has been considerable for many years.
Saint Petersburg, the former capital of Russia, stands on the eastern reaches of the sea and has a population of five million people. To reduce the environmental pressure on the Baltic, a multilateral initiative aims to reduce levels of phosphorous and nitrogen by deep biogenic removal from the treated discharge.
Treating 400 mgd
Located across the Columbia River from Portland, Ore., the City of Vancouver, Wash., has distinguished itself as a leader in effective sanitary sewer system management by maintaining adequate capacity, proactively maintaining sewage infrastructure and minimizing cost for existing and new ratepayers.
Jefferson Parish, La., extends along a 15-mile-wide corridor west of and upriver from New Orleans. As demonstrated by the recent Hurricane Isaac, this parish is vulnerable to tropical storms and hurricanes from June through November in a region that is already known for high rainfall events throughout the year. To make matters worse, the structural and operational integrity of the parish’s sanitary sewer lines and pump stations are compromised by age and very minimal budgets to maintain the equipment in place.
The sewer utility for the City of Andalusia, Ala., is among scores of municipal and regional operations across the nation that benefited from the American Recovery and Reinvestment Act of 2009. Andalusia qualified for a $250,000 U.S. Department of Energy Block Grant. However, the proposed use—for replacing aging pumps at two lift stations along the municipal sewage collection system—had to be fully demonstrated to be eligible.