Riverhead pursues innovative method to reduce and reuse sludge produced at its sewer plant

The Riverhead Town Board set a public hearing last night to bond money for a new $10.1 million sewer district improvement project that would cut the costs for its transportation of “sludge cake” to landfills and allow it to be used as a soil conditioner by residents and businesses.

The project calls for the installation of an innovative process at the district’s waste treatment facility on River Avenue that will reduce the total volume of dehydrated sludge produced at the plant — and that, in turn, will reduce the district’s ever-increasing cost of transporting it to a Pennsylvania landfill for disposal. Sewer District Superintendent Michael Reichel said the current cost of hauling and disposing the sludge is $500,000 — 10% of the district’s yearly budget. 

“It’s harder and harder to get rid of sludge and the cost is going up more and more,” Reichel told the town board at its work session March 3. “We had a 10% increase [in cost] this past year. It’s a two-year contract. And I can only imagine that in two years it’s going to increase again. It’s not going to go down.”

The town would be seeking a loan of not more than $10.5 million for the project. Assuming the whole project is financed over 20 years through the New York State Environmental Facilities Corporation Clean Water State Revolving Fund low interest loan program, the project would cost $107,400 per year, with a $537,000 annual debt service, according to estimates by the town’s engineering consultants H2M. The project will save an average $429,600 per year, according to the estimates.

“The savings that we are going to have is equal to the amount that we’re spending on the bond to make the improvements,” Reichel said in an interview Wednesday. “We’re kind of saving money right away. And then later on, when we’re not hauling out anything and it’s being reused, that’s really where you’re going to see the total end of the project.”

The end goal of the project is not just to reduce costs — but to eliminate those costs all together. 

The autothermal thermophilic aerobic digestion process — also referred by its parent company Thermal Process Systems as ThermAer — in addition to decreasing the amount of sludge cake the district needs to dispose of at a landfill, turns liquid sludge into a U.S. Environmental Protection Agency ‘Class A’ biosolid, an unrestricted, nutrient-rich and reusable matter that can be used to improve the physical qualities of soil. 

The long-term plan is to give the soil conditioner away for free to local businesses and residents, Reichel said. “We’re really looking to use it for ornamental uses, which is your grasses and your plants, your flowers, those sorts of things,” Reichel said.

The River Avenue facility is expected to produce roughly 6,000 pounds of sewage per day at full design flow, H2M’s report states. The sewage is aerated in holding tanks in liquid form prior to thickening and dewatering operations that produce sludge cakes. The ThermAer process would  increase the concentration of sludge cakes from 15-20% solids to 25-35% solids, according to H2M’s report. 

The ThermAer process uses jet aeration to optimize the performance of naturally occurring microorganisms that consume organic material, according to Thermal Process Systems’ website. The sludge is then transferred to a reactor and undergoes nitrification and then denitrification, which decreases ammonia and soluble microorganisms. A coagulant is then added, resulting in a smaller amount of sludge cake with a higher concentration of solids than before. 

The project will repurpose three tanks at the facility and construct a new building housing controls and pumps for the operation of the reactors needed for the autothermal thermophilic aerobic digestion process, Reichel said. The plan also includes the construction of a storage house for the sludge in the winter months, when nobody is expected to use the soil conditioner.

Reichel said the town considered the project’s construction in 2020, but didn’t find it cost effective enough. He said increased prices for transportation of the sludge cakes to landfills now make the project a net positive investment.

Reichel said he visited a sewer facility in Geneva in upstate New York to see the process in action. He said the city hasn’t put anything in a landfill and “have no problem getting rid of the material.”

According to H2M, the minimum annual debt services for the upgrade would be covered by a 109% increase in sewer district taxes, which would end up equaling $1.860/$1,000 assessed value for the full district area, $0.294/$1,000 assessed value for the partial sewer area and $8.594/$1,000 assessed value for the commercial sewer extension area.

The Community Development Agency is also pursuing a state grant that can cover up to $2 million for the project. 

“If we would get the grant, there’s no reason why we shouldn’t do this, because we’d be paying more money doing what we’re doing as opposed to doing this project,” Reichel said to the town board.

The Town Board spoke positively about the project during the work session March 3.

“This is a no-brainer,” Councilman Frank Beyrodt said.

“It definitely is a proactive approach. And it’s great to see you have gone down those lines and thank you for your work,” Supervisor Yvette Aguiar said.

“It’s always nerve racking when somebody says we’re going to bond either $8 or $10 million. But for what we’re already paying out on this, this makes economic sense all together,” Councilman Ken Rothwell said.

The public hearing on the bond authorization for the project is scheduled for the Town Board’s regular meeting on April 5 at 2 p.m.