City of Saline Wrestles With Expensive Questions Around its Wastewater Treatment Plant

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 06/20/2018 - 01:25
Saline's wastewater treatment plant is located off of South Monroe Street, just west of the Saline River.

Problems with Saline’s wastewater treatment plant (WWTP) go back many years. Though it was out of site – out of mind for many residents, those living near the plant have often suffered from intermittent noisome fumes.

The issue has received sharper focus in the last five years. Not only did it sometimes stink, but the plant was wearing out. Toward the end of 2012, City Superintendent Gary Roubal told City Council that upgrades would be necessary.

This led to a two-phase project, ultimately costing taxpayers over $4 million dollars, to replace worn parts and add some needed auxiliary equipment.

Phase one work was awarded to Franklin Howerda Company in May 2013 at a cost of about 1.3 million dollars. In addition, Tetra Tech was paid to oversee the project. The objective was to upgrade the anaerobic digester which processes sludge and turns much of it into gases (carbon dioxide and methane.)

The work on phase two was awarded to Weiss Construction Company, LLC in April 2015 at a cost around $3 million. This project had many facets, but it included replacing 25-year-old RBCs (Rotating Biological Contactors), building a new facility for receiving septage trucked in from neighboring townships, and structural repairs.

“The investment was to try to bring our plant up to current standards,” Council member Dean Girbach said. “There was a lot of work that hadn’t been done in twenty -- twenty-five years. It was really trying to get us to the point where we had a safe and reliable plant.”

Without these needed repairs, the WWTP could have become inoperable. Then the septage would have really hit the fan -- as they say. However, the timely repairs prevented this and the project was completed in the spring of 2017.

But something was still amiss. Throughout the expensive repair project, the odor problem seemed only to be getting worse. Residents began asking if the repair had actually increased the olfactory offense.

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The Odor Issues

Some of the odors were caused by the upgrade process. For example, a contractor error caused an overflow of unprocessed sewage into the Saline River in May, 2014. Likewise, work on the RBCs in the summer of 2016 required opening them, releasing normally contained odors.

Most often, however, the stench could not be attributed to a specific action. Consultants from Tetra Tech could not isolate the problem. Could the upgrades have made the miasma worse?

No actual processes were changed during phase two. Bob Scull, Water and Wastewater Treatment Superintendent, said he had expected the phase two repairs to diminish odors. Unfortunately, they didn’t.

Not only were the longsuffering neighbors of the WWTP gagging. On some days the smell reached downtown Saline and all the way (literally and metaphorically) to City Hall.

City Council was embarrassed by the problem and elevated it to one of their highest priorities. This time, however, they wanted to be sure they did their homework. This time they wanted a scientifically sound, data-driven solution.

At a work meeting in October 2016, City Council members met with a representative of Webster Environmental Associates, Inc. from Louisville, Ky. They presented a study proposal solicited by the city through an RFP (Request for Proposal) to study the odor problem.

At a Council meeting the following month, Council approved a contract with Webster for about $100,000, to study the odor sources and recommend solutions. Some citizens objected that the cost of the study was too high and did nothing to fix the problem.

Study would also delay a solution. City Manager Todd Campbell pointed out, however, that they had tried shortcuts in the past and the results were disappointing. This time they would get it right.

Webster, collaborating with Tetra Tech, commenced the project quickly. They began the first series of tests in late November of 2016. These tests assessed odor emissions during cool damp weather, while a study in July of 2017 provided results in warm weather.

Webster presented a preliminary report in March of 2017 and their final report in August of 2017. In the intervening time, Brian Rubel of Tetra Tech organized a field trip for Council members and the City Manager to visit two successful odor control operations in West Michigan.

Two Council members, Christen Mitchell and Janet Dillon participated in the field trip, along with Campbell and some employees of Tetra Tech. The group visited Grand Rapids and Grand Haven.

“We looked at communities that were very similar, that had houses close to their waste water treatment plants and had successfully managed odor issues,” Mitchell said.

On the trip, they saw two types of odor control systems, biological and activated carbon. Campbell said that this allowed attendees to judge the effectiveness, size, noise and other aspects of these systems. Mitchell said it was a valuable exercise.

Nevertheless, the study by Webster was the most important tool in deciding how to deal with the vexing vapors. In an extensive report, Webster detailed their study methods, results, and conclusions.

They used several methods of studying the odors both quantitatively and qualitatively. During the two studies, they analyzed samples to chemically identify odiferous gasses and they continuously monitored hydrogen sulfide levels at various locations. They also utilized an odor panel.

An odor panel is a group of people who are paid to sniff air samples and rate their pungency. Air samples collected at various times and locations are serially diluted and the panel members judge how much dilution is necessary before the smell becomes unnoticeable.  A high dilution (Detection Threshold) number means the smell was strong.

The odor panel also attempts to characterize the odors, e.g. skunky, rotten eggs, cabbage, etc. They also determine what dilution is necessary before they are unable to characterize the odor. This Recognition Threshold is generally a lower dilution than for detectability.

By careful collection methods, Webster was able to get these air samples to the odor panels and have them evaluated by the following day at a facility in Minnesota.

Various volatile sulfur compounds may cause odor from wastewater systems. The most common one is hydrogen sulfide (H­2S) which is described as smelling like rotten eggs. Mayfly Odor Laboratory tested for a variety of these and H­2S was the primary offender in Saline.

The report indicated that, as expected, odor production was higher in the summer than in the winter. Several measurements were about three to four times greater in the warm weather sampling.

Webster also utilized reports from citizens to identify which parts of the city were most affected. The overwhelming number of odor reports came from neighborhoods east and southeast of the WWTP, consistent with the WWTP as the source and a prevailing west wind carrying the smell.

With these and other measurements, Webster drew conclusions about what parts of the system were creating the stink.

One early discovery was that there was a problem with the Duall Chemical scrubber. This device, installed in 1996, is intended to cleanse the air from a couple of the early stages of the waste treatment process. Webster discovered that it was removing only about 15 percent of the H­2S.

While many components of the WWTP had been upgraded, this aging device was not. After not cleaning the gasses it was blowing the smell up into the air. “It was actually exacerbating the odor,” Campbell said.

In the first round of tests, a second chemical scrubber, mostly used to process air above the RBCs, was found to remove about 99 percent of the H­2S that passed through it. However, at the beginning of the July testing, it was functioning poorly.

Webster discovered that the chemicals used to deodorize the air had run out. The scrubber worked properly after it was refilled.

This second scrubber, from ERA Tech, is nearly as old as the Duall, and it is reaching the end of its effective lifetime too. Unfortunately, it will not be repairable, because the manufacturer has gone out of business.

During the winter testing, the city was not receiving septage from outside sources. Consequently, septage did not contribute to the total odor. During summer testing, however, the city had resumed receiving septage and it contributed more than half of the total odor emissions.

Other significant contributors to odor emission were the headworks building, the Duall scrubber, grit channels and splitter boxes.

One source of odor that had not been previously considered was the Southside lift station near Wilderness Park. Though its overall contribution is small, it could be significant locally.

Council member Mitchell said that although the Webster study was costly it was “absolutely worth it.” She said that past decisions hadn’t always been data driven, but this one will be.

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Odor Abatement Plans

Webster Environmental also provided a list of options for fixing the odor problems along with their associated costs. The solutions all involve tightening containment of odor generating processes and creating a system of ducts to route odors from all sources through a scrubber.

What is different in the various plans is the type of scrubber chosen. There are three broad categories of odor abatement systems, chemical, biological, and activated charcoal.

Chemical scrubbers mitigate odors by oxidizing odiferous sulfur compounds to less smelly and less volatile compounds. This process, which the city has used in the past, requires regular filling with chemical oxidants that can become quite costly over the course of plant operation.

Carbon filters capture odor causing molecules by adsorption on their surface. Properly prepared carbon can hold a lot of H­2S (and other odorants) but the carbon must be replaced when it becomes saturated.

Biological scrubbers remove odors through the action of bacteria growing on a porous matrix. The bacteria metabolize the odorants to less smelly compounds. These systems also require occasional replacement of the matrix.

Council members evaluated the options both from efficacy projections and cost over time. They were also guided, to some degree, by the visit some of them made to other Michigan wastewater treatment plants.

Of six options suggested, they chose the one that appeared to both remove nearly all the odor and do so at the lowest cost. Unfortunately, that cost is still millions of dollars on top of the recent millions spent to refurbish the plant.

The plan is to utilize both an activated carbon system and a bioscrubber. A carbon system will be used to treat air from the RBCs and the septage receiving building, while air from all other sources will be treated with the bioscrubber.  A separate carbon adsorption system would also be used to control odor at the Southside Pump Station.

Besides changing to a new type of scrubber, the proposed revision would assure that emissions from all processes, not just some, will be contained and routed to the scrubbers.

In August of 2017, Council voted to approve borrowing up to $4 million dollars to pay for the odor abatement work. They chose to borrow through the State Revolving Fund to obtain the lowest interest rate.

In April, Council voted to award a contract to E & L Construction Group for about $3.3 million dollars with another $325,000 going to Tetra Tech to oversee the project. The final expenditure will be over $4 million, because a few extra upgrades were included. Besides the odor control measures, a new back-up generator is being purchased for a pump station at the Sauk Trail Business Park and a new effluent flood pump for the WWTP.

These expenses will not be paid through the general budget, i.e. from property taxes, but through user fees. Residents and industrial customers should expect further increases in their utility bills.

E & L believes they can complete the project by next spring.

The new system will also be headed by a new Water and Wastewater Treatment Superintendent. Robert Scull (who has borne the brunt of criticism for the past several years) retired in early May and Interim Superintendent Mark Fechik has been in charge for the last month.

The city recently hired Steve Wyzgoski to be the new superintendent. His start date is June 25.

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The Future of Wastewater Treatment in Saline

Eight Million dollars later, how will the refurbished WWTP fare in the coming decades? Assuming all goes according to plan the city will have a fully operational and nearly odor-free system for 20 – 25 years before major repairs are needed.

The annual cost of operation of the new system will also be lower. The city has been spending about $107,000 a year to supply chemicals and electricity to the old chemical scrubbers. With the new scrubbers, the operational cost should be reduced to about $80,000 a year.

Yet some concerns remain. The plant is currently processing a volume of waste that is about 66 percent of maximum capacity. As new houses and businesses come on-line this number will grow.

The State DEQ (Department of Environmental Quality) requires that when the system reaches 85 percent capacity the city must prepare a detailed report on how they intend to prepare for future growth. And growth is happening.

According to City Superintendent Roubal, some of the growth has been anticipated for decades and sufficient capacity was built into the system in preparation. This is illustrated by what is happening at the north end of town.

The old Layher Farm property, along both sides North Maple Road, was broken into four parcels. The southwestern most parcel, north of the UAW building, became the Maplewood Farms subdivision. The southeastern most parcel was purchased by Liebherr Aerospace and is gradually being filled with an expanded industrial campus.

The two northern-most parcels, constituting 72 acres, are being purchased by Grand Sakwa Properties for development into a community of single family homes. The property will be annexed to the city under a 425 agreement with Pittsfield Charter Township.

“Those parcels fall under a 1981 automatic annexation agreement with Pittsfield Township,” Mayor Brain Marl said. “The agreement states that, if and when those properties are sold and poised for development, that they would be brought into the city of Saline.”

The growing Leibherr campus and especially the added new homes will increase the load on the WWTP. However, both the WWTP and the piping system on the north side of town are adequate for this challenge, officials say.

The increased load will not bring the plant up to 85 percent of capacity.

“My understanding is going from 67 to 85 [percent capacity] is something around 1000 or 2000 additional homes,” City Manager Campbell said, “so currently we should be fine.”.

But will it always be that way? The Master Plan for the City of Saline shows UDAs (Urban Development Areas) on the west side extending partly into Lodi and Saline Townships. Many City officials are thinking ahead to be ready if that happens.

“Yes, I do expect the city to grow,” said Marl. “I’m supportive of smart strategic growth. I’m hoping it will happen and I believe it will happen gradually and that we will be able to plan and respond accordingly as things progress.”

“We can’t grow a lot unless we annex land,” Mitchell said. “We just don’t have a lot of growth capacity in the city as it stands now. So that’s one of the challenges, is that in order to stay healthy as a community it would probably be good for us to grow and expand our tax base.”

“The townships in which that potential growth could happen haven’t wanted to really proceed with how that should be handled,” Girbach said. “You’ve got Saline and Lodi and York, and most of those townships have been not really pro-growth, they’ve been more for sustaining the status quo.”

“You can’t push for growth and be the city that wants all of this without offending all the government bodies around you,” Girbach lamented.

About two years ago, a group called Saline Ventures proposed the development of 117 acres of farmland in Saline Township on the southwest edge of the city. The project, between Michigan Avenue and Austin Road, would include a mix of residential and commercial development and include over 200 units.

To bring this project into Saline, however, would be very expensive. It is not just that it would increase the load on the WWTP, but the infrastructure is not in place to transport the expected volume of water and wastewater.

Saline City officials told the developer of the expenses and explained that the city was not prepared to pay. Realizing the cost that would be added to the project, the developer chose not to connect to city utilities.

The developer’s fallback plan was to connect to a private wastewater treatment facility previously built to serve the River Ridge manufactured home community. City of Saline officials told the developer that the land could not be annexed unless they chose to use city utilities, so annexation is currently off the table.

Perhaps this episode illustrates that the path to annexation will not be smooth.

Nevertheless, the possibility of continuous growth was very much in the minds of city leaders as they deliberated the recent expenditure for the WWTP. Would the odor control features be expandable? Could the existing plant be modified to increase its capacity?

The answer to both of these questions appears to be yes, within limits. The new odor control system will allow for expansion by adding components to it. Capacity could be increased by newer technology or some added equipment.

“I didn’t want to put this pile of money into something that’s going to be no good in a few years,” Mitchell said. “So, if we’re expanding, my idea is that we stay there and we expand that site. Then we have not wasted money.”

Other leaders agree, but there are further considerations. Expansion at the current site is limited by the confines of the property and future regulatory actions could require new processes that cannot be incorporated there.

At some point the city will need to make a choice, one full of risk because, as Girbach noted, “you never know if that future growth [of the city] is going to really be there.”

“It’s pretty much three options,” Girbach said. “Either a brand-new site somewhere outside of the city which then becomes more regional, not necessarily ours; expanding our current city facility and maybe even expanding it within the area that it currently is at; or looking at another regional organization.”

City Council is considering the possibility of hiring a consultant to study the options.

“Until we really know what it means in terms of dollars, capacity and all these other issues, we’re only guessing,” Girbach said.

Regional systems are becoming more common. YCUA (Ypsilanti Community Utilities Authority) is a good example. This authority provides water and wastewater services to well beyond the city of Ypsilanti.

YCUA also provides services to Charter Township of Ypsilanti, Pittsfield Charter Township, Augusta Township, Sumpter Township and Superior Township. Since neighboring Pittsfield is one of their customers, it would not be too much of a stretch for Saline to connect at some future date.

The regulatory environment, the complexity, and the cost of upkeep of wastewater systems make it increasingly expensive for smaller communities to maintain their own systems. Many communities now find it far more economical to contract this service to regional plants.

The downside of such an arrangement is that the city has to pay for infrastructure to connect and would lose control of billing.

Of course, Saline could choose to spearhead the development of a new regional facility that would serve townships to the south and west. This would require building a new facility at a new location.

“If we want to have one giant regional system, versus all these little ones, you’ve got to invest some serious money,” Girbach said. “The only way that would happen is if all the townships and the city decide ‘OK, I’m going to put money into this and here’s what we’ll do.’”

Construction at a new location would be pricy, not only because it would require construction of an all new plant, but like a potential connection to a YCUA, extensive rerouting of piping would be required.

“Building a new plant is huge money, I mean you’re talking upwards to probably $75 to $100 million,” Girbach said.

The city has already had to pay for the ongoing WWTP upgrades. Other large expenses include the Recreation Center repairs and staying ahead of the deterioration of city streets. However, the city has recovered much since the recession.

“We’re having growth in our tax base,” Girbach said. “The recovery in the evaluation of property and everything is allowing for revenue to increase, so it’s not like we’re getting behind the eight ball.”

This healthier financial position, if it continues, will help with ease the pain if more expensive solutions to wastewater treatment are needed.

Bob Conradi's picture
Bob Conradi Is a retired pharmaceutical scientist who has redefined himself as a photographer and journalist. He has lived in Michigan for 36 years and in the Saline area for 10. He enjoys researching and learning about new ideas. Reach him at [email protected] Follow him on Twitter at @RobertConradi.