~By Dr. Mary Lusk, UF Soil and Water Sciences Department, Gulf Coast Research and Education Center
The Florida Department of Environmental Protection announced last year a Septic Upgrade Incentive Program that will help offset the cost to homeowners of upgrading conventional septic systems to advanced systems for enhanced nitrogen removal. The program offers cost sharing up to $10,000 for individual homeowners in certain parts of the state to upgrade or replace their septic systems. The following frequently asked questions provide details about the program, why it is needed, and how homeowners can take advantage of it.
1. Why is nitrogen from conventional septic systems a concern in Florida? Nitrogen is one of the nutrients that can fuel harmful algal blooms and impair water quality in the state’s coastal and inland waters. Of the state’s 30 first magnitude springs, 24 are impaired by excess nitrate-nitrogen, an inorganic form of nitrogen that is highly mobile in the environment and readily available as a nutrient source to the organisms that cause algal blooms. There are 2 million septic systems in Florida, and most of these are conventional systems that have minimal ability to remove nitrogen. Therefore, septic systems are one source of nitrogen to the groundwater that feeds our springs. Other potential sources of nitrogen to Florida’s groundwater and springs include urban and agricultural fertilizers, livestock waste, atmospheric deposition, and wastewater treatment facilities.
2. Why do conventional septic systems remove very little nitrogen? Conventional septic systems contain just 2 parts: a septic tank and a drainfield. Wastes from a home enter the septic tank, where solids settle out and are slowly degraded by anearobic bacteria in the tank. Liquids in the waste–called septic tank effluent–move onward through a series of pipes to the drainfield, which is a area of soil in which the effluent is allowed to infiltrate. Most of the nitrogen in septic waste is in the form of organic nitrogen, but in the anaerobic conditions of the septic tank this organic nitrogen is quickly converted to ammonia-nitrogen. Ammonia-nitrogen, in turn, is quickly converted to nitrate-nitrogen in the oxygen-rich soil environment. Nitrate is highly mobile in soils and can leach quickly to underlying groundwater. Conventional septic systems have no mechanism to capture or remove this nitrate-nitrogen. Most conventional systems do a great job of protecting human health from the pathogenic organisms in wastewater, but they were never designed to remove nitrogen. So, the simple answer to this question is that conventional septic systems were designed from a public health perspective and not a nitrogen removal perspective. A conventional system removes only about 30% of the nitrogen that enters it (mostly through breakdown of solids in the septic tank). Read more about how septic systems work and about how they treat nitrogen.
3. What if my conventional septic system is well maintained and regularly inspected and pumped? Won’t that keep it from contributing nitrogen to the environment? It’s great to regularly inspect, pump, and maintain your septic system. This prevents system failure and the potential transport of pathogenic organisms to the environment. However, it will do very little if anything to prevent the transport of nitrogen from your system to the underlying groundwater. Again, these conventional systems do not remove nitrogen.
4. Are there septic system technologies that do a better job at removing nitrogen? Yes, enhanced nitrogen removal technologies are available and a list of some of the commercial options available in Florida can be found at the Florida Department of Health website. These systems take advantage of natural nitrogen cycle processes to enhance nitrogen removal. Ammonia-nitrogen leaving the septic tank is first passed through an oxygen-rich zone to promote its conversion to nitrate-nitrogen. The nitrate is then passed through a low-oxygen but carbon-rich zone to promote the process of denitrification, a chemical pathway in which nitrate is converted to a nitrogen gas that escapes to the atmosphere, thus removing nitrogen from the groundwater pathway. There are a number of options for these systems, and homeowners that wish to or need to use these technologies can expect to pay $10,000 to $20,000 to modify or replace their current systems.
5. Are some Florida residents required to replace or modify their conventional septic systems to include advanced nitrogen removing technology? Yes. Under legislation from the 2016 Florida Springs and Aquifer Protection Act, residents who live in the Priority Focus Area of an Outstanding Florida Spring will potentially need to upgrade their conventional systems. The Priority Focus Area (PFA) is an area of land around a spring system that has been deemed to be most vulnerable to nitrogen transport. On lots less than 1 acre in size within a PFA, all new septic systems must have advanced nitrogen removal technology. Additionally, residents in PFAs may be required to upgrade to enhanced systems if their conventional system ever fails and needs repair or replacement. Read more about the Florida Springs and Aquifer Protection Act. You can find out if you live in a PFA by visiting FloridaDEP.gov\PFAMap.
6. How can homeowners get help with the cost of upgrading or replacing their conventional systems? The Florida DEP has rolled out the Septic Upgrade Incentive Program to help offset the costs of this. This program provides assistance up to $10,000 for homeowners and is available now to homeowners in PFA areas in Citrus, Hernando, Leon, Marion, Orange, Pasco, Seminole, Volusia, and Wakulla counties. Find out more about this program and how to apply here.
7. How is University of Florida-IFAS Extension helping to spread the word? UF-IFAS Extension personnel are developing a toolbox of educational materials that can be used by Extension agents and local governments to educate homeowners about septic systems and their connections to water quality, as well as how to take advantage of the DEP cost sharing program. A special training workshop for IFAS personnel and any other interested government stakeholder will be held in Gainesville on June 20, 2019. The workshop will provide specific training on the basics of septic systems, their functioning, advanced systems and legislative requirements in PFAs. The training workshop will also roll out the “toolbox” for resident education, which will include a website, videos, factsheets, and other educational products. IFAS personnel can register here and other stakeholders can register here.