Sewer lagoon cleanup needed

Alexis Barker
NLJ News Editor
 
City engineer Mike Moore estimates that sludge removal at the city of Newcastle’s sewer lagoon will cost $500,000, if addressed in the near future, according to information he provided during a sewer committee meeting on Dec. 7.
“We could wait, but it will cost more later. We have to
pay for what is removed,” Moore said. “I feel like now
is a good time to address sludge removal.”
Upgraded in 1987, with operation beginning in 1988, the facultative lagoon treats wastewater through a biological process, without mechanical processes, according to Moore’s information. The sewer was upgraded after a 1981 Environmental Protection Agency 201 study, a requirement of the Federal Sewage Works Grant under the Clean Water Act, addressed more stringent regulatory requirements for discharging effluent into Little Oil Creek. 
The lagoon consists of four cells, which provide not only additional capacity but also the ability to treat the wastewater more effectively. The excess sewer effluent is managed by a combination of evaporation and irrigation. 
The primary cell, A, has a surface area of 16 acres, cell A flows into cell B, which covers 28 acres, then into cell C’s 16 acres and, finally, into cell D’s 20 acres. 
Currently, flow into cell A is being diverted into cell B, Moore explained, allowing for the built-up sludge to dry for removal. “The sludge or ‘biosolids’ is solids in the sewer that settles or (is) formed from biological processes acting on the organic material that settles. The sludge also has material in it that does not break down such as disposable wipes, rags, grit and other miscellaneous trash,” Moore explained in an email. “Primary constituents we look to improve and reduce through the treatment process are biological oxygen demand (BOD), total suspended solids (TSS) and bacteria (E-Coli/Fecal Coliform). Also, ammonia levels are a concern as well as pH and oil and grease amounts.”
In 2017 and 2018, Moore said, sludge surveys were performed by the U.S. Rural Utilities Service and the estimated amount of sludge was 1 foot in cell A and 7 inches in cell B. Each cell has an operating depth of 5 feet. 
“It is not uncommon for properly functioning lagoons to operate for 30 years prior
to cleaning the sludge, but it is also common
to have more frequent sludge clean out intervals,” Moore said in an email, noting that Newcastle’s lagoon has been operating 32 years. “In theory, the sludge removal could be prolonged but this will not reduce the eventual clean out costs. We would not want to have more than two foot of depth (sludge) as that would result in less than three foot operating depth exceeding DEQ (Department of Environmental Quality) guidelines.” 
Not only does sludge removal impact the operations of the lagoon system, it will also help control odors. While the cleanout is fairly expensive, estimated by contractors to be $1 million for cells A and B, Moore said the city has been saving money in an account earmarked for the lagoons. 
“The city has an account that money is set aside yearly for maintenance of the lagoon that will be used to help cover the cost,” Moore said. “Budget money is from the sewer enterprise account and not as greatly impacted as general funds, which have projected budget shortfalls.” 
The decision on when to move forward with the cleanup project was also influenced by uncontrollable factors, according to Moore. 
“A factor in deciding to go forward with the sludge cleanout was the low levels of the lagoon. The low levels is the result of additional irrigation use from an exceptional dry summer this past year,” Moore said. 
The focus of the cleanup, cell A, has been drained, and now Moore reports that he will have a topographic survey done to better define the actual volume of sludge. This will also help provide a more accurate cost. 
“Sludge cleanout is not planned in cells C and D as the sludge accumulation is anticipated to be minimal. We will, however, be doing further investigation to verify,” Moore said. “On cell B, we may attempt an innovative technique of bio stimulation, where the sludge is stirred to dissipate the volatile components of the sludge mass as a gas.” 
No matter what is done for removal, the disposal of the sludge is regulated by the EPA Part 503 biosolids rules. 
“The plan will be to primarily dispose of the sludge by land application with non-bio-degradable material taken to the landfill. Initial sampling has been done of the sludge, finding it has a low heavy metals, providing a more favorable categorization for land application per EPA 503 requirements,” Moore said. “I hope to put together a bid package for late winter, early spring and target work to begin after July 1 to coincide with the next fiscal year.” 
The sewer committee suggested that Moore explore ways to reduce costs, including using city crew time for as much work as possible. Moore noted that most of the cost is trucking the sludge.