The staff at the Downriver Wastewater Treatment Facility has faced plenty of challenges. Their collective experience, perseverance, teamwork and loyalty have led to 100 percent permit compliance for seven straight years.

They’re proud of that. “We have great employees who are on top of their game,” says Dan Alford, superintendent of the plant in Wyandotte, Michigan. “They are our first line of defense to catch and fix any problems that arise.”

Built in 1939, the plant has been upgraded numerous times, creating operations and training issues. Designed for 225 mgd maximum rated flow, the plant averages 50 mgd during dry weather. Annual average flow is 65 mgd, but the flow can rise as high as 260 mgd during heavy rain.

The facility has downsized from 100 to 50 employees, saving around $43 million in personnel costs. Today, a pool of 15 operators keeps things running smoothly around the clock, along with laboratory and maintenance teams. Contributing to their success is strong collaboration between Wayne County and the 13 communities that rely on and invest in the plant.

Many upgrades

The Downriver plant serves 284,000 residents in Allen Park, Riverview, Belleville, Romulus, Brownstown Township, Southgate, Dearborn Heights, Taylor, Ecorse, Van Buren Township, Lincoln Park, Wyandotte and River Rouge. A joint management committee of the county and communities, formed in 2005, facilitates input on operation and maintenance. The county invites a representative from each community to review and comment on engineering proposals and construction bids.

Major upgrades have allowed the plant to keep up with treatment regulations. Primary treatment was expanded in 1962. In 1975, secondary treatment was augmented with a pure-oxygen-fed activated sludge process. Two clarifiers were added in 1988, and a belt press was added in 1995. From 1997-2001, the plant replaced major equipment and added capacity, including a UV disinfection (TrojanUV) system to replace chlorine gas. Today, all equipment is tied into a SCADA system, upgraded in 2009, with iFIX Proficy software (GE Intelligent Platforms).

The 34-acre plant includes an administration complex with a front office, laboratory, operations service building, maintenance area and repair shop. The plant includes seven primary clarifiers (Evoqua Water Technologies), five aeration trains (Veolia), six secondary clarifiers (Evoqua). Discharge is to the Trenton Channel of the Detroit River.

Biosolids are dewatered and conveyed to roll-off containers, then trucked to landfill. Biosolids processing equipment includes primary sludge and transfer pumps (Vaughan), waste activated sludge booster pumps (WEMCO), polymer feed system (Evoqua), sludge storage tanks (Ovivo), thickened sludge transfer pumps (Penn Valley, Swaby-Lobeline), belt filter presses (Bilfinger Water Technologies) and centrifuges (Alfa Laval).

Stormy weather

Severe rain storms test the plant’s operations. “In August 2014, we got 3 1/2 inches of rain in one day, most of it in just a few hours,” Alford recalls. “Plant flow rose from 50 mgd to as high as 260 mgd. In cases of high flow, operators must place all the tanks and processes in service, which involves opening many valves and monitoring additional plant process equipment and pumps. Thankfully, the actual sewage is a fraction of the high flow, and the excess is rainwater. So, we don’t have a problem meeting our permit because the flow is so dilute.”

Operators also manage multiple pump stations and retention basins that must be staffed during a storm event. Says Alford, “Because we’re in the business of protecting public health, our operators understand and always respond.”

Wet or very cold weather can affect landfill access, leading to high solids inventory at the plant. The facility team is considering emergency storage for dewatered biosolids as part of capital improvement planning.

The peak flow for the primary treatment system is 150 mgd, and 125 mgd for the secondary treatment. The system is designed so that any flow that might bypass primary treatment receives secondary treatment and vice versa. No wastewater can bypass both primary and secondary systems.

Wet-weather flows up to 125 mgd are treated like dry-weather flows, passing through preliminary and primary tanks, low-lift pumps, aeration basins, final clarifiers and UV disinfection.

Wet-weather flows above 125 mgd, up to 150 mgd, partially bypass the secondary treatment system.

Wet-weather flows above 150 mgd, up to 225 mgd, bypass the primary system but receive secondary treatment. Flows greater than 150 mgd are brought into the plant through a tunnel pump station instead of the pump house. All the bypassed flows are combined and disinfected.

Staying on track

The plant team members pay attention to detail and act quickly to correct sudden changes in effluent quality. “Every day we review our dashboard report, which shows the permit limits and actual results,” says Alford. “This report is emailed to plant management, so if we are close to the limits we can quickly get back on track. Our lab staff also sees the analysis numbers, and if they don’t look good, they will bring this to the operators’ attention. That gives us a head start on making changes.”

The laboratory team handles sample analysis for the Downriver plant, Detroit Metropolitan Airport, two pump stations, stormwater retention basins and the industrial pretreatment program. Matt Best, lab manager, oversees chemists Don Massie, Tony Azzouz and Trisha Dotson (assistant lab manager and chemist positions were awaiting new hires as of the end of 2014).

They perform about 44,000 tests a year. Besides testing influent, primary effluent, final effluent and sludge and dewatered cake samples, they calibrate and support the UV disinfection system. The assistant manager is responsible for the quality program, standard operating procedures, metals analysis, methods validation and inventory.

Greater efficiency

Fifteen years ago, the county began looking at how to increase operating efficiency. “The private sector was ramping up, and the county wanted to be more competitive,” says Alford. “We didn’t want to turn the operations over to a private company, so we made a conscious decision to right-size. When the housing bubble burst, property values dropped and tax revenue fell off a cliff. Even the big industries are doing more with less and are not staffed at the same levels they were.”

The county reduced personnel through attrition and by relocating people to other divisions. By 2009, the staff was reduced by half, and the following year every county employee took a 10 percent pay cut.

“Some people took two days off a month without pay, but rotating shifts made this option impossible for operators who took the pay cut and continued to work a full month,” says Alford. “The last raise anyone got was several years ago, and we have lost a half dozen employees since then. Hiring has become difficult because of this.”

Alford says plant management tries to maintain morale by having employee get-togethers when the plant wins compliance awards: “We have a breakfast where we acknowledge their contributions to operations. We also encourage them to take advantage of training opportunities. And, of course, we give kudos when they do a good job.”

Ongoing training

The plant’s numerous upgrades have created training challenges. “We’ve spent $10 million to $15 million a year for the past 10 years on upgrades, which is a good thing but creates a constant learning curve,” says Alford. A 2012 centrifuge upgrade involved training multiple people and rotating shifts. The plant also upgrades computers and software every five years.

Training is conducted by equipment vendors and the sessions are videotaped. The plant also uses online training programs developed by 360water of Columbus, Ohio. These training modules use a series of interactive Web pages with a test at the end.

Operators are skilled at minor maintenance, such as pump and valve greasing; the maintenance team handles heavier jobs. Operators also get to use their creativity. “One time we had violent shaking in a length of pipe,” says Alford. “You could hear this strange sound, but it didn’t happen all the time. So, one night, operator Jason Greenlee followed the sound and used his personal cellphone to video record a 10-inch-diameter pipe that was shaking and bouncing around. He posted the video to YouTube so management staff could watch it and determine the best course of corrective action.”

Future projects

As part of a $10 million upgrade, the plant will renovate the laboratory starting in 2015 in two phases to minimize disruption. Renovation of the solids-handling complex is to be completed in mid-2015. “We have already upgraded the solids-handling process by rehabbing two of the four thickened sludge storage tanks, installing new sludge mixers and tank lids, and installing new pumps in the pump gallery,” says Alford. The complex still needs new automation and a new roof.

The team is looking at biosolids options that include drying to more than 90 percent solids and pelletizing for sale as fertilizer, and lime stabilization before landfill.

The staff is challenged to run the plant during major construction. “We have not had six months when there was not a contractor on site, and it takes close coordination between our operators and the contractors to make this work,” says Alford.

He advises older plants to rebuild rather than renovate an existing plant: “It’s very difficult to add on while operating, so if you have the room, I recommend building a whole new process and then demolishing the old one.”

Previous upgrades have involved building up rather than out since there is no more land for development. “The plant’s design reminds me of an M.C. Escher drawing,” jokes Alford. “But all those stairs are good exercise for the staff.”