Lift Stations

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Stops sulfuric acid corrosion

Problem

Corrosion on manholes in the Lafayette (La.) Utilities System sanitary sewers required constant maintenance. The utility, looking for ways to prevent it, tested dozens of epoxies, linings, and other technologies.

 

Solution

In October 2001, the utility tested ConMICShield from ConMICShield Technologies on a troublesome manhole. The liquid concrete antimicrobial kills sulfuric acid-producing bacteria on contact, and its molecules bond in the concrete so it cannot wash off, chip off, peel off, delaminate or pinhole.

Technicians from AP/M PERMAFORM mixed the antibacterial agent with Permacast MS 10,000 high-strength, shrinkage-compensated, fiber-reinforced mortar. It reduces chloride ion penetration, and reinforces and seals the structure. They applied the mix with a Permacast spin-caster for bidirectional centrifugal compaction. It applied the liner uniformly flow way to road way for consistent thickness and easy inspector verification.

 

Result

After nine years, the manhole showed no sign of deterioration. 800/662-6465; www.conshield.com; www.permaform.net.

 

Device simplifies instrumentation

Problem

The District of Lunenburg in Whynott’s Settlement, N.S., added a septage receiving station to the landfill site. Part of the treatment train is a chlorinated duplex vertical turbine pump station delivering effluent from the sludge processing facility to spray nozzles for dispersal.

The pump station, active only at certain times of day, discharges through twin vertical turbines and an overflow to a holding pond. Monitoring devices were needed to control the VFD pump, measure the flow to the pond via a V-notch weir, and sense levels in the pump station.

“We were looking at three different instruments all in the same chamber,” says Ghislain Hachey, P.E, application engineer at Marathon Fluid Systems in Moncton, N.B. “It would be easier on the operator and more economical for the city if we could find one meter that did it all.”

 

Solution

Hachey chose the DLT 2.0 differential level transmitter with two PZ15 ultrasonic sensors from Greyline Instruments. The meter alternates the display between level and overflow rates. It uses 4-20 mA signals to control the turbines and chlorination and monitor flow over the weir. The simple interface has a built-in five-key calibrator, two programmable control relays, and a large backlit LCD display.

 

Result

“The transmitter is a powerful instrument that simplifies complex applications in a single analytical package,” says Hachey. 315/788-9500; www.greyline.com.

 

Pump eliminates debris and drag

Problem

Disposable wipes in the 350 gpm duplex Andresen Pump Station in Vancouver, Wash., contributed to excessive costs for outsourced maintenance two to three times a week. Electricity usage also increased from drag caused by fouled pump impellers.

 

Solution

The municipality replaced the 40 hp pumps with 25 hp Flygt N-pumps from ITT Water & Wastewater. The units have a 4-inch-diameter discharge throat, semi-open impeller, and relief groove in the volute that streamline the passage of material without sacrificing hydraulic efficiency.

The impeller blades with flattened, backswept leading edges sweep solids from the center to the perimeter of the inlet. As the impeller turns, rags and other long stringy material are forced into the spiral-shaped relief groove, helping tug material from the impeller into the volute. A guide pin in the volute pushes solids away from the impeller, enabling them to be pumped away.

 

Result

Eliminating clogging and pump drag saved the utility $20,000 per year in energy usage. 704/409-9700; www.flygtus.com.

 

 

Pump resolves maintenance issues

 

Problem

The 1 mgd Wise Street lift station in Bradford, Ohio, had 20 hp 6-inch duplex discharge pumps, but mechanical seal leaks shut them down without notice. Replacing the proprietary seals averaged $3,000 per pump and took weeks, straining the maintenance budget. Primary operator Jay Roberts wanted pumps that warned of potential seal problems, were faster and less expensive to repair, and resisted clogging.

 

Solution

The village purchased a Barnes 4SHMD 4-inch solid-handling submersible enclosed monovane pump with 25 hp motor from Crane Pumps. Installing it in the lift station required a 4- by 6-inch slide rail adapter to fit the existing base elbow, and a MiniCAS adapter relay to connect to the existing control panel.

The tandem mechanical seals have silicon carbide seal faces on the pump end and carbon/ceramic at the motor end, both with Buna elastomers and stainless springs and retainers. A large oil-filled chamber lubricates the seals. A two-conductor probe in the chamber senses and alarms before water can enter the motor housing. The large shaft diameter and tapered impeller drive minimize shaft deflection and vibration.

 

Result

An alarm connection to the plant’s SCADA system warns of seal issues. The new pump in the lift station has been trouble free. Roberts plans to replace the second existing pump with another 4SHMD pump. 937/615-3544; www.cranepumps.com.



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