Council Studies Issue Of Wastewater Plant Capacity
February 22, 2017 at 7:23 p.m.
By David [email protected]
Tuesday night, city council was given an idea of the plant’s status and what’s being recommended to address it.
Mayor Joe Thallemer said he asked the plant’s utility manager, Brian Davison, and city engineer, James Emans, to come to the council meeting and “give us maybe one of our first public glimpses at some of the larger considerations that we’re going to have to work through as we develop a final plan.”
He said the two overriding issues are whether the plant will go to an anaerobic or aerobic system and at what capacity it will be expanded to. Everything from engineering and cost data to average flows and growth is being studied to help the city predict what to plan for, he said.
Tuesday’s presentation, Thallemer said, was just a first step for the council and public to understand the circumstances.
Davison began the presentation with a history of the plan and some of the options available, followed by engineer Gary Ruston, with Wessler Engineering, providing the advantages and disadvantages of those options.
The old plant came online around 1950, Davison said, and operated until 2012. In the early 2000s, the city decided to build a new plant because the old plant was in need of major renovations and landlocked for future capacity needs.
“The plan was always to close the old plant and divert all the flow to the new plant, all of which happened in 2012,” Davison said.
The plant that replaced the old one is located off Silveus Crossing, just south of U.S. 30.
While showing a picture of the current plant, he pointed out three white buildings, which are the aerobic digesters. He said they’re quite energy intensive and “we’re running a 200 horse power blower right now to feed air to those three digesters, and that’s where the aerobic, anaerobic discussion comes in. That’s what determines if you have an aerobic or anaerobic plant, is basically the type of digestion you have.”
The anaerobic process happens without oxygen being provided.
The current plant is a 3.9 million gallons per day (MGD) rated plant, which is a Class III plant. In Indiana, Class IV is the highest rating, Davison said. In 2016, he said the average flow was at 85 percent capacity, but in 2013 it was at 89 percent capacity.
“Those numbers are important because at 90 percent capacity, IDEM can issue an early warning sewer ban. Basically, what that is, is IDEM saying you’re at 90 percent, what’s your plan for the future? If we were to reach 100 percent capacity, IDEM can issue a sewer ban which prohibits new connections and that’s not a situation the city of Warsaw wants to be in. It would prohibit any new homes, it would prohibit any new business, it would prohibit existing businesses from expanding and increasing flow to our plant,” Davison explained.
Going over some charts on the base flow of the plant, he noted that over the last 10 years the base flow has increased “800,000 gallons per day or 3.5 percent per year, which is above average for a community to grow and flow at that rate. It’s not a bad problem, it just means there’s growth ... But that higher-than-average flow increase has led to the plant being at capacity sooner than expected.”
In early 2015, Davison said the city began looking at some of its options, with the evaluation completed in August 2015. Three options were evaluated: expanding the plant to 6 MGD, a 50 percent increase; expanding it to 8 MGD, a 100 percent increase; and plant improvements only. He then showed a chart comparing the different flow increases.
He mentioned IDEM is pushing for more regionalized sewer systems, and smaller communities weren’t building their own sewer treatment plants but sending everything to one larger plant.
The next big decision that needs to be made is the size of the expansion. If it’s expanded to 6 MGD, capacity is reached in about 13 years. For 9 MGD, it’s about 20 years, he said.
In August 2016, Davison said they began to evaluate a fourth option, going to an anaerobic plant, which was the option that was chosen.
“It’s the best way to move forward and for Warsaw’s future treatment needs,” Davison said.
Ruston listed the advantages and disadvantages of the aerobic and anaerobic options.
For aerobic, the two advantages are a lower initial construction cost and familiarity.
Disadvantages include higher long-term operating and maintenance costs, high energy consumption and more production of sludge. It would also be limited to 10 MGD in capacity at the current site.
Advantages for anaerobic include lower operating and maintenance costs. The disadvantage is only higher initial construction cost.
The old plant was anaerobic and the plant staff is familiar with that process, Ruston said.
“When you put all of this together, all in all, the anaerobic option, looking long term, is a better option for the city treatment plant expansion,”?he said.
If the plant is expanded 50 percent to 6 MGD, the annual cost of the aerobic option with sludge disposal would be about $649,000, while the anaerobic would be $428,000.
Ruston said if design work is started in March, design would take 10 months, permits would take four months, bidding two months, financial/bonding two months and construction would take 22 months. Under that scenario, the anticipated completion date would be July of 2020. New phosphorous removal facilities must be in operation by May 2020, Ruston said.
Thallemer said the city wasn’t at a point yet where it knew the costs of constructing an anaerobic or aerobic plant. The city first must decide the size of the future plant.
“It’s a significant amount to go to anaerobic, there’s no question about that. But, what’s the difference? I don’t know that we’ve got to that point yet,” Thallemer said.
Davison said he’d like to return to the council in three or four months with a recommendation for plant expansion size and cost estimates.
“The idea tonight was to show you what decision making is going to have to go into this. None of the decisions have really been made. Most engineers will tell you when you hit a certain million gallons a day, anaerobic becomes more cost effective in the design of running that plant. If you build a 9, 10 million gallon-a-day plant, you would go with anaerobic to start with,” Thallemer said.
Emans added, “It is a big picture to look at this. To some extent, engineers have to look in a crystal ball as to how much is enough, because it’s never cheaper than today to build this type of projects. Costs are always going up, but there’s going to be a balance between what we think our growth is going to be and those costs for that expanding plant.”
Thallemer said the city will look into whether federal funding is available.
Tuesday night, city council was given an idea of the plant’s status and what’s being recommended to address it.
Mayor Joe Thallemer said he asked the plant’s utility manager, Brian Davison, and city engineer, James Emans, to come to the council meeting and “give us maybe one of our first public glimpses at some of the larger considerations that we’re going to have to work through as we develop a final plan.”
He said the two overriding issues are whether the plant will go to an anaerobic or aerobic system and at what capacity it will be expanded to. Everything from engineering and cost data to average flows and growth is being studied to help the city predict what to plan for, he said.
Tuesday’s presentation, Thallemer said, was just a first step for the council and public to understand the circumstances.
Davison began the presentation with a history of the plan and some of the options available, followed by engineer Gary Ruston, with Wessler Engineering, providing the advantages and disadvantages of those options.
The old plant came online around 1950, Davison said, and operated until 2012. In the early 2000s, the city decided to build a new plant because the old plant was in need of major renovations and landlocked for future capacity needs.
“The plan was always to close the old plant and divert all the flow to the new plant, all of which happened in 2012,” Davison said.
The plant that replaced the old one is located off Silveus Crossing, just south of U.S. 30.
While showing a picture of the current plant, he pointed out three white buildings, which are the aerobic digesters. He said they’re quite energy intensive and “we’re running a 200 horse power blower right now to feed air to those three digesters, and that’s where the aerobic, anaerobic discussion comes in. That’s what determines if you have an aerobic or anaerobic plant, is basically the type of digestion you have.”
The anaerobic process happens without oxygen being provided.
The current plant is a 3.9 million gallons per day (MGD) rated plant, which is a Class III plant. In Indiana, Class IV is the highest rating, Davison said. In 2016, he said the average flow was at 85 percent capacity, but in 2013 it was at 89 percent capacity.
“Those numbers are important because at 90 percent capacity, IDEM can issue an early warning sewer ban. Basically, what that is, is IDEM saying you’re at 90 percent, what’s your plan for the future? If we were to reach 100 percent capacity, IDEM can issue a sewer ban which prohibits new connections and that’s not a situation the city of Warsaw wants to be in. It would prohibit any new homes, it would prohibit any new business, it would prohibit existing businesses from expanding and increasing flow to our plant,” Davison explained.
Going over some charts on the base flow of the plant, he noted that over the last 10 years the base flow has increased “800,000 gallons per day or 3.5 percent per year, which is above average for a community to grow and flow at that rate. It’s not a bad problem, it just means there’s growth ... But that higher-than-average flow increase has led to the plant being at capacity sooner than expected.”
In early 2015, Davison said the city began looking at some of its options, with the evaluation completed in August 2015. Three options were evaluated: expanding the plant to 6 MGD, a 50 percent increase; expanding it to 8 MGD, a 100 percent increase; and plant improvements only. He then showed a chart comparing the different flow increases.
He mentioned IDEM is pushing for more regionalized sewer systems, and smaller communities weren’t building their own sewer treatment plants but sending everything to one larger plant.
The next big decision that needs to be made is the size of the expansion. If it’s expanded to 6 MGD, capacity is reached in about 13 years. For 9 MGD, it’s about 20 years, he said.
In August 2016, Davison said they began to evaluate a fourth option, going to an anaerobic plant, which was the option that was chosen.
“It’s the best way to move forward and for Warsaw’s future treatment needs,” Davison said.
Ruston listed the advantages and disadvantages of the aerobic and anaerobic options.
For aerobic, the two advantages are a lower initial construction cost and familiarity.
Disadvantages include higher long-term operating and maintenance costs, high energy consumption and more production of sludge. It would also be limited to 10 MGD in capacity at the current site.
Advantages for anaerobic include lower operating and maintenance costs. The disadvantage is only higher initial construction cost.
The old plant was anaerobic and the plant staff is familiar with that process, Ruston said.
“When you put all of this together, all in all, the anaerobic option, looking long term, is a better option for the city treatment plant expansion,”?he said.
If the plant is expanded 50 percent to 6 MGD, the annual cost of the aerobic option with sludge disposal would be about $649,000, while the anaerobic would be $428,000.
Ruston said if design work is started in March, design would take 10 months, permits would take four months, bidding two months, financial/bonding two months and construction would take 22 months. Under that scenario, the anticipated completion date would be July of 2020. New phosphorous removal facilities must be in operation by May 2020, Ruston said.
Thallemer said the city wasn’t at a point yet where it knew the costs of constructing an anaerobic or aerobic plant. The city first must decide the size of the future plant.
“It’s a significant amount to go to anaerobic, there’s no question about that. But, what’s the difference? I don’t know that we’ve got to that point yet,” Thallemer said.
Davison said he’d like to return to the council in three or four months with a recommendation for plant expansion size and cost estimates.
“The idea tonight was to show you what decision making is going to have to go into this. None of the decisions have really been made. Most engineers will tell you when you hit a certain million gallons a day, anaerobic becomes more cost effective in the design of running that plant. If you build a 9, 10 million gallon-a-day plant, you would go with anaerobic to start with,” Thallemer said.
Emans added, “It is a big picture to look at this. To some extent, engineers have to look in a crystal ball as to how much is enough, because it’s never cheaper than today to build this type of projects. Costs are always going up, but there’s going to be a balance between what we think our growth is going to be and those costs for that expanding plant.”
Thallemer said the city will look into whether federal funding is available.
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