Skiing Visitors Bring Peaks and Valleys in Flow for the Clean-Water Plant in the Resort Community of Ludlow

A small Vermont clean-water plant earns recognition for efficient nutrient removal and successful handling of seasonal flow spikes.

Skiing Visitors Bring Peaks and Valleys in Flow for the Clean-Water Plant in the Resort Community of Ludlow

Chuck Craig reviews building plans with (from left) Joe Gaudiana, assistant chief operator, and Christopher Strong, operator in training.

The Village of Ludlow is home to about 2,500 Vermonters. Its clean-water plant often treats wastewater from up to 25,000 people.

That’s because the plant also serves the Okemo Mountain Resort, a major skiing destination, and the many seasonal homes and condominiums that surround it. The quick ramp-up in flow on winter weekends and holidays can be challenging for the plant team.

Chuck Craig, chief operator, runs the village’s oxidation ditch treatment system with Joe Gaudiana, assistant chief operator, and Christopher Strong, operator in training. The three also take care of wastewater collections and the drinking water system, which serves only the village. “Everything from the source water protection area to the outfall in the Black River is under our care,” Craig says.

Evidence that they do their jobs well is the Facility Excellence Award in Wastewater that was presented in 2019 by the Green Mountain Water Environment Association, recognizing the facility’s performance in nutrient removal and handling of load spikes.


Ludlow lies about 100 miles south of the skiing mecca of Stowe. The wastewater treatment facility has a 1.05 mgd design capacity; it handles 273,000 gpd on average during summer and 542,000 gpd on average in winter.

Built in 1971, the plant has been upgraded at various times. It was constructed with two shallow oxidation ditches, two 50,000-gallon Spiraflo clarifiers (Lakeside) and drying beds for biosolids. In 1992, these were replaced with two 9-foot-deep oxidation ditches with mechanical surface aerators (also Lakeside), each holding 438,000 gallons and operated in parallel. An additional 100,000-gallon Spiraflo clarifier was also installed.

Another upgrade in 1992 added two aerobic digesters, which now function mainly for thickening and storage; biosolids are shipped off site for processing. The headworks includes a 0.25-inch Raptor fine screen (Lakeside). An upgrade now in progress will add new influent pumps and process-control pumps in a new pump building, replace all controls and add a SCADA system. The work was scheduled for completion by the end of 2020. 


In operation, influent passes through the fine screen unit, which washes and squeezes the screenings to prepare for landfilling. “Pumps then lift the wastewater to an anoxic selector tank where we starve it of oxygen a little bit,” Craig says. “That process gets the phosphorus and nitrogen removal going.”

In the selector tank, installed 15 years ago, the influent is quiescently mixed with return activated sludge with no aeration. “That starves the microorganisms of oxygen to produce endogenous respiration,” Craig says. “It tends to kill off the bacteria that we don’t want, like the filamentous, and breed the good ones. In summer we denitrify pretty regularly, so we don’t release much nitrogen. And the process binds up the phosphorus a little bit, too.”

From there, the flow enters the aeration tanks, followed by clarification. The clarifier effluent is disinfected with chlorine and dechlorinated with sodium metabisulfite before discharge to the river.


Outside the skiing/tourist season, only one aeration basin and one clarifier operate. “We only run half the plant,” Craig says. “We lower the solids concentration in the biological area to 1,200 to 1,500 mg/L (from 2,000 to 2,500 mg/L in winter) because we don’t have as much demand.”

The flow begins to increase when Okemo Mountain Resort opens, usually by Thanksgiving. “We get variable flows from then until April,” Craig says. “During the week, we’re still at 270,000 to 300,000 gpd. But on any busy weekend or holiday, we can see 700,000 to 900,000 gpd, and if it rains, over 1 mgd.

“The village leaders were smart in the past. They built the plant big enough, so we have some flexibility with tankage. We have the two big ditches and the three clarifiers, and that helps buffer the load. We try to keep ahead of it a little bit by monitoring our mixed liquor suspended solids. The wasting process is a manual thing. There’s a lot more sludge wasting and sludge handling during the winter. We can adjust the dissolved oxygen levels in the ditches by raising and lowering the water level.”

Six pumps (Pentair Myers) handle both return and waste activated sludge. Operators manually open and close valves to shift between RAS and WAS. Gaudiana notes, “Our percent removal of BOD and TSS is about 96% on a regular basis. We must be doing something right.” Plant operation is simplified by all-gravity flow once the influent is lifted after the headworks.


The collections system also flows by gravity except for one lift station in a corner of the village that handles a small wastewater flow. Craig and his team maintain the lines and about 650 manholes.

“At least once a year, we hire a company to come in for a couple of days with a Vactor truck and a big jetter,” Craig says. “We hit all the known trouble spots. We have a small trailer jetter of our own (Spartan Tool) so if we get in a bind, we can go clean out a line. The most trouble we have is with the tops of manholes. We have to adjust the tops when they pave the roads. We try to change out a manhole or two every year.”

The drinking water system draws from Jewel Brook, a few miles south of Ludlow. “They built a collection area where there used to be a natural upwelling of groundwater,” Craig says. “Since then, a flood-control dam was built with intake galleries underneath that catch that same water. It runs by gravity to the village.”

The water is chlorinated and the pH is raised to 7.4 before it is fed to the distribution system. “We’ve got some distribution valving to keep our water tanks full,” Craig says. “We have two tanks for fire protection, and all the fire hydrants are on that system.”


The wastewater facility is staffed on weekdays from 7 a.m. to 3:30 p.m. and otherwise runs automatically. The operators alternate night and weekend on-call duty, wearing pagers for notification of alarms.

“Every day of the year someone is here doing the testing,” Gaudiana says. “We check all our process controls every day. We test the domestic water for pH and chlorine residual. One of us does that every third weekend. It’s a two-hour day.”

Preventive maintenance is performed on a regular schedule. Gaudiana, with a background in automotive racing engines, handles most of the maintenance and in-house equipment repairs.

While the plant runs smoothly most of the time regardless of seasonal load swings, “Once in a while things happen, and we have to wait a day to figure it out,” Craig says. “We rely on settleability. One day it will settle just fine, the next day it may not and the following day it goes back to being just fine. Possibly something comes with the influent that we don’t know about, and it upsets the process a little bit. It may take us a day or two to gather information and determine what’s going on.”

Sometime microscopy provides an answer; at other times, the DO level in the ditches can provide clues. “Occasionally we adjust the return solids rate to the ditches,” Craig says. “We try not to do that often if we can help it, but we’re able to do it.”


Craig and Gaudiana took different paths into their careers. Both have Grade 4 (second highest) wastewater operator and Class 3 (groundwater) water operator licenses. Craig, a Vermont native, studied carpentry and cabinetmaking at a technical high school and worked in the homebuilding business around Ludlow for about 20 years.

“A friend of mine went into the wastewater field right out of high school and is now a public works director,” he says. “The municipalities in Vermont have a pretty good pension plan and good health insurance.” An opening came up in Ludlow, and Craig came on board as an operator in training. He became an operator after three years and has been chief operator for the past four years.

Gaudiana, from Connecticut, grew tired of urban life and moved to Ludlow after his daughter graduated from college. He worked for the village seasonally for two years doing lawn maintenance and other tasks; in winter, he did snow removal and other work for a property management company. He was hired on at the treatment facility seven years ago.

Craig takes special pride in helping protect the Black River, a pristine water fed by mountain streams and an attraction for sport anglers. He and Gaudiana share dedication to the village. Craig observes, “One thing that drives us is customer service. If any of our customers call us or the municipal office with a problem or complaint, we drop what we’re doing if at all possible and attend to that immediately.”

Gaudiana notes, “We couldn’t do what we do without the people above us making the decisions — the elected boards and Scott Murphy, village manager. They leave us to do our jobs and trust us to do the right things.” 


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