Inspections can identify undetected issues to prevent sanitary sewer overflows and the fines that can accompany them.
by Steve London, Steve London Associates, for Flygt, a Xylem Brand

Wastewater utility organizations have been caught in the same budget constraints as most other public services during what some refer to as “The Great Recession.” After years of coping with staff reductions, a limited budget for outsource services and deferred maintenance, the use of the run-to-fail strategy by some sanitary districts increased for assets such as lift station pumps.

Of course, there are exceptions among wastewater utility managers who follow preventive maintenance practices. The reasoning is simple. Pump station failures usually translate into contingent federal and state environmental violations and penalties in the wake of sanitary sewer overflows (SSOs).

A Proactive Maintenance Case Study

Although the Costa Mesa Sanitary District continues to stretch its operating budget, it has not compromised the California utility’s proactive—rather than reactive—maintenance strategy. The utility strives for reliability from the duplex pump stations along the 224-mile long collection system that cross-stitches the 16-square-mile service area. General Manager Scott Carroll has practiced annual preventive maintenance (PM) inspections since joining the district four years ago. The district then outsources repairs on an incremental basis as they emerge throughout the following year to the contractor awarded the initial inspection work.

Costa Mesa Sanitary District (CMSD)Costa Mesa Sanitary District (CMSD) serves a population of more than 100,000 residents in a 16-square-mile area. Wastewater is collected and conveyed to the Orange County Sanitation District treatment plants. CMSD was honored as the 2012 Collection System of the Year by the California Water Environment Association in recognition of overall management practices.

The practice has allowed Costa Mesa to prequalify one of the few contractors in the area that perform repair and maintenance work on sewer pump stations. Incidents involving clogged or failed pumps could then be assigned by individual work orders to the contractor holding the annual repair and maintenance contract. The approach relies on a thorough inspection of each asset.

“Our district doesn’t believe in run-to-fail,” Carroll emphasized. “That imposes too much risk and the potential for heavy fines here in California where the regional water quality control boards have policies even more stringent than the federal EPA.”

“We’ve actually improved our proactive approach this year,” he added. “The annual PM inspection had even higher importance following a failure at a major station.

The incident occurred last August when the largest SSO in the utility’s 70-year history occurred. The failure of the uninterrupted power supply unit in a complicated control panel at the pump station unleashed an estimated 77,000 gallons of wastewater into the stormwater system that discharged into a neighboring drainage canal. It flowed into the Back Bay, which is protected by state environmental policy.

The wastewater temporarily closed Newport Dunes Aquatic Park, a popular public recreation area for canoeing, paddle boats and swimming. The closure was further aggravated by the closure occurring during Labor Day weekend when fun outings were scuttled for scores of residents from affluent Newport Beach and Orange County.

CMSD continued a policy of proactive inspection and preventive maintenance.

“When I presented my report to the board, I noted we had our fewest SSOs but, unfortunately, also had the largest spill last year in our history,” Carroll said. “We got their approval for a 90-day contract to thoroughly inspect the 20 pumps in the most critical 11 stations to identify any undetected issues that could prevent them from operating reliably and at optimum levels.”

The Southern California service office for a wastewater pump manufacturer chose to submit a direct bid on the PM inspection rather than shop repair and parts to contractors previously awarded the work. Not only was the direct bid the lowest amount, but Carroll felt the global pump manufacturer offered the most expertise and reach in support for the contract.

To meet the expedited 90-day schedule mandated by the contract terms, the California office of the wastewater pump manufacturer supplemented its local field with help from its sister office. Each pump station then underwent a one- or two-day thorough inspection after pulling each pump and examining controls, electronics, volutes, impellers and other components.

Although the wastewater pump manufacturer service trucks rival a “repair and parts shop on wheels,” it can provide a temporary bypass pump as a backup when repairs require the resources at the service shop.

The field technicians adhered to a 20-point checklist that disclosed deficiencies attributed to possible past oversights. The procedure used thermal imaging evaluations, along with hands-on techniques that revealed extensive ragging in the check valves and volutes, worn bearings, seals and O-rings, loose wiring, and an improper lubricant in the pump sleeves. The improper lubricant could have shortened the life of the pumps.

The two-man inspection teams also discovered motors close to failure and a few wetwells that lacked a backup pump. If a pump failed at these stations, the absence of a reserve pump could have set the stage for a spill.

The deficiencies were compiled into itemized reports on a station-by-station basis noting priority conditions recommended for action. The extent of the problems at many locations was unusual because some of the pumps were fairly new.