The State of Lagoon Treatment in Missouri

FEATURE Review by Phil Walsack The State Of Lagoon Treatment In Missouri

Missouri has more than 900 Facts And Figures Left: Pacific’s new lagoon aeration system municipal governments, and many own was designed by Burns & McDonnell in 2019. The design flow of these 334 systems Right: Clarence’s lagoon in winter. Achieving and operate their wastewater systems. combined is 53.8 million gallons per ammonia compliance can be difficult when In addition to municipal ownership day (MGD) with actual flows of 37.3 the winter arrives. (cities, towns, and villages), public MGD. While most consider lagoon sewer districts and county governments technology a “smaller city” wastewater own an additional 124 systems. It is not solution, six cities discharge more than balance of discharging lagoons. While common knowledge, but there are more 1.0 MGD. Five of the six cities serve the number of communities is large, wastewater permits (called National more than 7,000 people. The six cities the population served is only 184,000. Pollutant Discharge Elimination System (with seven discharge permits) have a These smaller entities have a combined Permits or State Operating Permits) than combined design flow of 12.4 MGD, and design flow of 34.1 MGD and an there are communities; some entities an actual flow of 9.1 MGD. Overall, the actual flow of 23.2 MGD. Interestingly, may have more than one wastewater larger lagoon discharging communities actual flows are decreasing as the facility. represent 59,300 people. rural populations continue to move to Generally, wastewater treatment urban living environments. Permitted There are only 12 additional technologies can be divided into four actual flows are decreasing even though cities greater than 3,000 population major categories, including: mechanical; smaller systems have difficult inflow and discharging effluent from a lagoon lagoon; community septics; and non- infiltration (I&I) issues to solve. I&I is treatment system. The 12 cities have a discharging. The subject of lagoon stormwater and/or groundwater that combined design flow of 7.3 MGD and treatment systems has long been a enters the collection system piping prior an actual flow of 5.0 MGD. The mid- difficult and economically challenging to treatment. sized lagoon discharging communities reality for Missouri. Discharging lagoon represent 54,100 Missourians. systems are prevalent in the state. Ammonia There are 334 lagoon facilities that The next dataset brings into focus are permitted to discharge treated the most challenging and vexing of A primer about ammonia is a wastewaters into another water body Missouri’s wastewater challenges. Two worthy endeavor before reviewing such as a river, stream, creek, ditch, hundred ninety-two communities with water quality standards and regulatory losing stream or lake. 315 wastewater permits make up the compliance issues. Ammonia, and its

10 theReview November/December 2019 toxicity, is a major driver in any lagoon More Stringent Regulations promulgated by the United States treatment discussion. If you are not a Environmental Protection Agency These fun facts and statistics lead chemistry nerd, you can skip the rest (USEPA). It is referred to as “ammonia to a tough and expensive discussion of this paragraph, and just know that reduction for the protection of mollusks.” about the water quality discharging ammonia is toxic to fish. For the rest Mollusks include mussels and gill- from lagoon facilities (often referred of us chemistry enthusiasts, ammonia breathing snails. It is very important to as effluent). Over time, water quality is a byproduct of animal and human to note that regulations governing the standards have been tightened (i.e., waste. It is also described as a nutrient “ammonia reduction for mollusks” have made more stringent) by federal and that contains nitrogen and hydrogen. not been approved by MDNR. This is not state governments. Three periods of It is a colorless, pungent gas that is the law of the land…yet. regulatory tightening are noted. In highly soluble in water. Its chemical 2003, the Missouri Department of For Missourians, it is important formula is NH in the un-ionized form, 3 Natural Resources (MDNR) adopted not to confuse the two ammonia and NH + in the ionized form. Total 4 water quality standards for ammonia. regulatory reductions. Typical ammonia ammonia is the sum of NH and NH +. 3 4 In February 2014, MDNR classified concentrations in treated effluent under Ammonia is a preferred nitrogen- an additional 90,000 miles of streams, the current water quality standard are 1.4 containing nutrient for plant growth. initiating a period of more stringent milligrams/Liter (mg/L) in the summer It can be converted from Nitrite (NO ) 2 water quality standards for the state’s months (April 1 to Sept. 30), measured and Nitrate (NO ) by bacteria and then 3 water bodies. This period included new as a monthly average and 2.9 mg/L in used by plants. Ammonia is also one of regulations for “ammonia reduction the winter months (Oct. 1 to March 30), the most important pollutants because for the protection of fish.” Previously, again measured as a monthly average. it is common and can be chronically many wastewater facilities discharging Adherence to daily maximum values toxic (causing lower reproduction and to streams did not have ammonia are also applicable in all wastewater growth) and acutely toxic (causing limits. With five-year wastewater permits. Generally, these values would death) in aquatic life. The neutral, un- permit periods, watershed-based be cut in half by the proposed USEPA ionized form (NH ) is the most toxic. 3 permit synchronization, and extended regulations, if Missouri chose to adopt Temperature and pH also play a role. At schedules of compliance, the impact of them in the future. higher temperatures, concentrations of these ammonia limits are now being felt NH persist. As pH increases (especially When dealing with the current 3 statewide by smaller communities. ammonia reductions (protection of fish above 7.2), NH4+ is converted to NH3 and ammonia’s toxicity increases in Third, and on the regulatory horizon, populations) it is important to view water. is the 2013 water quality standards capital improvements necessary to

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www.mocities.com 11 2) Land Application Fifty-seven communities apply their wastewater directly to the land surface and do not allow it to reach a regulated water body. If land is available to purchase or lease, non-discharging systems provide cost-effective treatment because many of the water quality sampling requirements are avoided. A quick reference to this type of treatment is described in the “Water Quality Program Fact Sheet” (PUB-02669) provided by the MDNR located on the Department’s website. 3) Batch Releases New Haven’s aeration system in their lagoon treatment system. A variation of non-discharging system is winter-time effluent releases. further reduce ammonia concentrations. of utmost importance. Flow monitoring, Effluent limits for ammonia are less In the future, Missouri regulators may even the most rudimentary analysis, is stringent if the effluent can be held seek future ammonia reductions (to extremely valuable. Smoke-testing and in the summer (not discharged) and protect mollusks). Elected officials must more advanced I&I source identification released in the winter months. Systems take a longer view of capital improvement are keys to lagoon performance. that aggressively manage their collection expenditures in this regulatory climate. Collection system performance is the systems reducing their I&I and have Spending rate-payer funds in the near most overlooked, and yet the most lagoon storage capacity, are candidates term must be weighed against longer- important, operational variable in for this type of treatment/release term water quality standards. lagoon treatment facilities. schedule. Another treatment variant is the land application of wastewaters Collection System Piping Options For Treatment Success during the summer months and the release of treated effluent in the winter Before a discussion of treatment 1) Non-Discharging months. options is made, the operational concept For the 292 communities with 4) Regionalization of “pipes before plants” is paramount. discharging lagoon systems, future The wastewater collection system treatment decisions are daunting, but The term “regionalization” has been (the pipes in the ground transporting not impossible. There are options. For in existence in Missouri for decades wastewaters to the treatment facility) is smaller communities that are located but has been under-utilized as a the most expensive asset a community more than five miles or greater from treatment technique. This term refers owns. No other capital investment is another community, a non-discharging to independent public bodies working more costly. Collection-system piping wastewater treatment system is a viable together to share the responsibility is buried deeper than any other asset option. The term “non-discharging” of treating wastewaters. This shared and it is laid to an engineered grade, means that the wastewater is applied approach could entail the construction allowing sewage to flow downhill in a to the land’s surface through a series of a new facility that serves multiple subterranean environment. In lagoon of sprinklers (like a center pivot or communities, or the pumping of discharging systems, the operation and traveling gun style). The local soils and untreated wastewaters from a smaller prudent maintenance of collection- vegetation naturally treat the wastes and community to a larger community system piping is more important than the wastewaters are not allowed to enter that has treatment facility capacity. the lagoon treatment system itself. a body of water before the soil absorbs it. An example of a regional wastewater Stormwater flows in the collection One of the primary reasons to consider a treatment facility in southwest Missouri system cause the lagoon system to non-discharging system is that existing is the Center Creek Wastewater under-perform or to malfunction or future water quality standards cannot Treatment Plant, into which flows completely. Removing excessive I&I be met by the existing lagoon or that a from the communities of Carterville, always improves water quality. I&I mechanical treatment process will be Oronogo, and Webb City are treated. removal allows wastewaters to linger too expensive. Operations of a non- A smaller community discharging in the lagoon longer. This gives the discharging facility is more akin to to a larger community is exemplified biological process more time to perform farming than traditional wastewater by the city of Gillam, discharging its work. Lagoon systems in Missouri treatment. It does not take much time untreated wastes to the city of Slater for have a combined total of 1,740 miles of traveling rural areas to understand that treatment. A reference to regionalization collection system piping. Understanding Missourians know farming. is described in MDNR’s Fact Sheet where this collection piping is located is PUB-02587. MDNR is serious about

12 theReview November/December 2019 this approach. They offer a grant program to regionalize more facilities. Most lagoon treatment systems in Missouri utilize more than one lagoon or cell to achieve regulatory compliance. These cells have different functions. If the effluent is to be released, it is critical to get the ammonia out of wastewater prior to discharge into a natural water body. One way to achieve this action is to aerate one or more lagoon cells. This means introducing a man-made source of air into the wastewater so that it drives out the ammonia, volatizing it into the atmosphere as nitrogen and hydrogen gas. Dissolved oxygen concentrations ranging from 2.0 mg/L (minimum) to 5.0 mg/L (optimal) are desired. The four, non-mechanical treatment options discussed above are not an all- inclusive list, merely the beginning. Other options abound including: constructed wetlands; aeration lagoons equipped with insulated covers; submerged attached growth reactors (using buried reactors to take advantage of geothermal heating); moving bed biofilm reactors; and other newly- emerging technologies. Greenfield’s traveling gun sprinkler system for land applying treated wastewater effluent. Conclusion It is an engineering consultant’s goal to protect public health and the environment in an affordable way while positioning a community for more stringent regulations. At times, lagoon augmentation is the right option. Most often it comes down to a community’s risk tolerance and the costs associated with an ongoing reliance on lagoon technology. After considering the costs and operations of non-mechanical treatment options, a community could ultimately decide to construct a mechanical wastewater treatment plant. The engineering community can assist by identifying the best path forward that balances conveyance (the collection system) and treatment. Missouri’s engineering firms stand ready to assist communities to make these important community investments. Phil Walsack is a business development manager for Burns & McDonnell headquartered in Kansas City, Missouri. Mr. Walsack is currently based in the Joplin Field Office (MO). He is responsible for business development in Missouri and the "Four- States" region. He has advocated for municipal utility viewpoints at state and fedreal regulatory/legislative meetings, hearings, and presentation venues around Wastewaters from Carterville are pumped to a regional facility, the Center Creek the country for decades. Mr. Walsack has over 30 Wastewater Treatment Facility. years of experience in environmental issues.