F loods, hurricanes, power outages and high winds are just a few obstacles overcome by operators at the Octoraro Water Treatment Plant in Nottingham, Pa.

“Weather is our biggest challenge, especially with the changes it brings to the raw water quality,” says Patricia Stabler, chief of treatment and pumping for the Chester Water Authority, the plant’s owner. “We had three major floods in 2011 and Hurricane Sandy in 2012.” When there is a flood, the reservoir detention time shortens from weeks to hours, turbidity rises above 100 NTU, and dissolved organics increase. A dry winter can bring high nitrates in the Octoraro Reservoir. Rains can bring runoff from frozen farm fields.

Operators just dig in their heels and do whatever is necessary to make quality water. The plant team developed a detailed flood treatment strategy in 2010 and has steadily improved online instrumentation and water analysis. They also have strategies for minimizing nitrates and haloacetic acid formation.

Plant upgrades also create challenges. Several plant shutdowns were required during new high lift station construction and clearwell upgrades in 2012. “The plant was out of service for 12 hours, which took planning by the authority and contractor, since the plant is the sole source of water for our customers,” recalls Stabler.

Plant operators take part in the Partnership for Safe Water and earned the President’s Award in 2012 for maintaining Phase III status and meeting Phase IV performance goals. They did that in the same year the alum feed system was replaced and a new storage and feed system was started up. “The word that comes to mind is tenacity,” says Stabler. “The operators have to be more tenacious on a day-to-day basis. The Phase IV goals were achieved with consistent operator attention to the treatment process.”

In fact, the facility was notified on May 6 that it had officially received Excellence in Water Treatment (Phase IV) status.

New water source

In the early 1940s, the Authority needed a new water source because the Delaware River became polluted. The replacement was Octoraro Creek, 45 miles west.  A dam, reservoir, treatment and pumping facility, storage tanks and pipeline were constructed, and in 1951, the Octoraro Water Treatment Plant went online to supply 18 mgd to residents of Chester and Delaware County.

Other expansions followed; the plant now supplies up to 35 mgd to about 200,000 people. In 1969, as drought backup, the authority built facilities to bring water to the Octoraro Reservoir from the Susquehanna River. Improvements in 1991 brought river water directly to the plant. More recent upgrades include:

• Sodium permanganate feed system; ammonia feed upstream of the settling basins
• Settling basin modifications (plate settlers, effluent flumes, new chlorine, polymer and lime addition upstream of the filters)
• Polyaluminum chloride (PACl) feed system
• New filter media, valves and controls for 12 filters
• Liquid alum feed system and storage facilities

Easier for operators

Raw water changes in winter are much easier to deal with since the plant switched to PACl in cold months. “Its performance is far superior to alum,” says operations supervisor Gordon Miller. “No lime or polymer is required with PACl, so those are eliminated from the jar test. In general, if the settled turbidity begins to rise, we just increase the dose.”

New plate settlers in four basins have substantially lowered basin effluent turbidities, allowing the plant to operate four instead of six basins. Filter runs have been lengthened and backwashing has reduced. The liquid alum feed and storage system increased storage capacity, eliminated two outdoor heated storage tanks in a flood-prone area, and eliminated three indoor feed tanks on the top floor of the main administration building.

“We now have six storage tanks and four Flowrox hose pumps for dosing,” says Miller.

The tanks and feed pumps are housed in a new building with spill containment. Operators benefit from precise dosing control for each of the two treatment trains. They no longer have to routinely transfer alum between outdoor bulk tanks and indoor feed tanks.

Filter upgrades replaced aged hydraulically operated valves with motor-operated valves, increasing reliability and ease of operation. The change also improved filter flow control, simplified filter shutdown and substantially improved remote monitoring.

In 2012, the plant tested and purchased an online Chemtrac UV254 analyzer. “It gives operators real-time data, and the spectrophotometer helps us establish baseline organic levels and alerts them to increasing organic constituents that place an added demand on coagulation,” says Miller.

The plant also purchased a benchtop particle charge analyzer (Micrometrix) so that operators can determine the alum coagulant demand curve through titration. “This quickly provides the correct coagulant dose to reach the baseline charge established from the streaming current detector (also Micrometrix),” says Miller.

Going modern

Upgraded controls have been incorporated into the SCADA system. “When I started as operator, this was a manual plant, but now with the SCADA, it’s simpler to operate and we get more warning about potential problems,” says assistant operations supervisor Greg Johnson.

Plant modernization was gradual, allowing operators to get used to one upgrade at a time. “It wasn’t sprung on them, and most of them picked the technology themselves,” Johnson says. When new operators come on board, the experienced ones train them. A new operator is teamed with two experienced operators and trained until he or she is proficient in basic duties. The new operator then is teamed with an experienced certified operator and assumes shift duties. Training is supplemented with correspondence and online courses. In three years, new operators are to earn state Department of Environmental Protection certification.

The plant’s eight full-time operators, two relief operators and two supervisors work 12-hour shifts with two on duty at a time. Eight are DEP certified, and the two newest are working on certification. A 31-year veteran of the Octoraro plant, Miller holds Class A and E water licenses. Johnson, with 12 years at the plant, has Class A and E licenses.

The operators are Raymond Brantner, Kenneth Eller, James Freese, Steven Jacobs, Ted Moran, Steve Rowlands, David Sapp and Steve Young; relief operators are Edward Farber and David Paterson. The operators take pride in their work and freely collaborate.

“Many times we need multiple minds working on the same issue, and I can count on the entire operations, maintenance and laboratory team for that,” says Stabler. “We get support from other departments, and we have access to service providers and engineers.”

Beyond the plant

Operators also monitor the reservoir and dam and patrol the plant site. They remotely position and monitor valves and tank levels at a storage facility five miles away, remotely start and stop pumps, operate other equipment at the Susquehanna pump station 13 miles away, and monitor flow, pressure, sump levels and other parameters on SCADA.

They remotely monitor the levels of the two lagoons and the operation of the lagoon recycle pumps. “Operators must make sure there is room in the lagoons for process water discharged to them, and that the water recycled from them to the raw water for re-treatment does not adversely affect treatment,” says Miller.

Operators check the dam several times a day, particularly the toe drain, for leakage or abnormalities. An important job is flood watch during rain events. If the reservoir level is rising, a maintenance person is contacted to lift the reservoir tainter gates.

The plant has always complied with nitrate limits by blending the two water sources. “The Susquehanna source is a better-quality water, and nitrates are generally 2.0 to 3.0 mg/L in the winter, whereas the reservoir is close to 10.0 mg/L,” says Miller. “We calculate the flow from the Susquehanna needed to lower nitrate to below 8.0 mg/L.”

Disinfection byproducts (DBPs), specifically haloacetic acids (HAA5), are challenging in wet years. “Storms cause organic loading, which leads to DBPs,” says Miller. “We rely more on sodium permanganate to replace the oxidation of iron and manganese as we try to lower chlorine dosing. Susquehanna blending is another tool, since the Susquehanna waters tend to form fewer HAAs than the Octoraro and have lower chlorine demand.”

Meeting Phase IV

The plant entered the Partnership for Safe Water after Miller attended a Partnership summit in Hershey, Pa. Once the operators started working toward Phase IV, they realized they had to be more proactive in meeting stringent turbidity requirements. “We have real-time trending of the settled water and individual filter turbidity on most of the computers in the plant, specifically the control room computer,” says Miller. “Each sedimentation basin has an online turbidimeter, which gives us early warning if the coagulation/flocculation process is not optimized.”

Operators constantly monitor these trends. If filter turbidities are trending up, a backwash is triggered before the water reaches 0.100 NTU, the Partnership Phase IV goal. The streaming current detector and particle charge analyzer allows operators to troubleshoot the process early, before turbidity goals are exceeded.

“We do routine filterability index (FI) testing to verify coagulant performance,” says Miller.  “If any change is made to a coagulant dose, the results are verified using the FI test. I would say that striving to meet Phase IV goals has improved everyone’s understanding of water treatment techniques.”

Every month, the turbidity graphs (individual filter effluent, combined filter effluent, and settled) for the month are posted outside the control room. A graph for combined filter effluent from 2004 to the present shows all turbidity spikes. This gives operators visual feedback about their performance.

“Our plant improvements made it possible to meet the Phase IV goals from a plant configuration standpoint,” says Miller. “We have the tools in our toolbox, and it’s up to us to use them properly.” A good example was last fall after Sandy.

“One of the basins was offline for equipment replacement,” recalls Miller. “The operators’ quick response allowed us to meet Phase IV goals with just three basins online. In mid-November, the water temperature began to drop, and the alum performance began to suffer in treating the fine colloids left from the storm.”

The plant team had decided to begin feeding PACl about three weeks earlier than normal. “While waiting for PACl delivery, the turbidity of a few of the filters post-backwash briefly spiked above 0.100 NTU,” recalls Miller. “Rather than wait for it to drop during ripening, the operators immediately took the filter offline and filtered it to waste until the turbidity dropped below 0.100 NTU.”

It’s the kind of proactive thinking and collaboration that have made the Octoraro treatment plant a high-performing facility.