Community Alternatives for Septic Tank Replacement
Central Sewer System
One approach is to abandon septic tanks in place and connect the affected homes and businesses to central sewer. This option exists in many urban and suburban areas where existing sewer infrastructure is available, adjacent to the property, and the central wastewater plant has adequate treatment capacity to accept the additional connections. This situation is likely the best-case scenario. It typically involves the collection of a “tap fee” from the property owner to cover the cost of the physical hookup between the home and sewer system and an “impact fee” to offset the capital investment in overall treatment capacity at the central plant. Assuming a property owner with a septic tank is willing and able to pay these initial fees, which may total $2,500 to $5,000, there are no other adverse factors to consider. This type of “Septic to Existing Sewer” program can be offered on a first-come, first-served basis, utilizing public funding assistance to offset property owner costs, or may be mandated if certain events are triggered, such as the failure of a drainfield. Once connected to central sewer, the property owner will be required to pay a recurring sewer bill, which averages approximately $50 per month, but has no additional responsibilities.
In many cases, the existing or planned sewer system does not reach the location of the septic tanks. The cost to expand sewer infrastructure must be paid for by the new sewer customers who will connect to the infrastructure or with public funding, or a combination of both. These “Septic to Expanded Sewer” projects are more expensive, averaging approximately $25,000 per connection, and because of the high cost, they are almost always driven by compelling environmental or public health problems and supported with public funding. To reimburse the utility (or taxpayer) for the capital cost of the infrastructure, a state law requires adjacent property owners to connect to the infrastructure within twelve months. Even without public funding assistance, the utility may not be in a position to capitalize the infrastructure investment or maintain the infrastructure without the revenue generated from the new sewer customers connected to the system. The “mandatory participation” requirement creates a significant “social cost” that may make this approach unacceptable to the community. The social cost includes impacts to low income residents who, even if all up-front costs are covered by the program, cannot afford the monthly sewer bill. Another example is a resident who is simply unwilling to participate and challenges the local government decision to compel his or her participation. As with the previous scenario, once connected to the expanded sewer lines, the property owner will be required to pay a recurring sewer bill, which averages approximately $50 per month, but has no additional responsibilities.  §381.0065, Florida Statutes
Advanced Technology "Onsite Treatment And Disposal Systems"
When a septic tank must be replaced but central sewer infrastructure is not available or feasible, one solution is to replace the conventional septic tank with an advanced technology OSTDS, commonly referred to as an Aerobic Treatment Unit (“ATU”), Performance-Based Treatment System (PBTS) or sometimes by their performance certification (e.g. “NSF 40” or “NSF 245”). These systems typically utilize one or more treatment technologies or methodologies to improve the quality of the wastewater discharged into the property owner’s drainfield. If nitrogen reduction is required for environmental reasons, only a PBTS or NSF 245 system can be used, each of which is certified to achieve a minimum of 50% nitrogen removal efficiency.
A “Septic Upgrade” program has the advantage of being able to reach participants far beyond a sewer collection system, including in remote or inaccessible areas, such as barrier islands. The program participant must first obtain a permit from the county health department. The health department requires the use of pre-approved systems (costs range from approximately $10,000-20,000), a maintenance agreement between the property owner and an approved maintenance entity for the life of the system, and annual inspections for the life of the system. These additional requirements can cost the property owner an estimated $50-100 per month, depending on whether the service contract is inclusive of repair costs.
Other factors to consider prior to pursuing this programmatic approach include: (1) Minimum Nitrogen removal performance is 50%, which is far less than that required of regulated domestic wastewater treatment facilities; (2) The systems are not continuously monitored and are only required to be inspected annually, which means that a non-functioning unit could remain unnoticed by authorities for significant periods of time; and (3) With one permit and one annual inspection required per system, the regulatory/administrative overhead is extremely high. These factors, along with the high recurring cost to the property owner for maintenance, are adverse and will negatively impact acceptance of the model. On the other hand, the absence of common infrastructure avoids the social cost associated with a mandatory participation program.
DISTRIBUTED WASTEWATER TREATMENT SYSTEM (DWTS)
A DWTS is a new category of wastewater treatment system involving centrally managed, decentralized treatment technology, that was recently approved by the Florida Department of Environmental Protection (FDEP). Decentralized wastewater treatment is provided by Distributed Wastewater Treatment Units (DWTUs), installed at or near the point of generation. These DWTUs are virtually connected using existing wireless data networks to a central management system (e.g. a Supervisory Control & Data Acquisition System or “SCADA”), and in this configuration, the DWTS functions like a public wastewater collection and treatment system but without the physical sewer connection to each end user.
In a “Septic to Distributed Sewer” program utilizing a DWTS, septic tanks can be removed or abandoned and replaced with DWTUs. The DWTU will treat wastewater to effluent standards described in the FDEP permit and then discharge the treated wastewater safely underground, all under the continuous supervision of a professional wastewater operator. As a result, no wastewater needs to be piped to the utility for treatment. It is fully treated and disposed of in place.
This ability to treat wastewater with a professionally-operated DWTU is likely the best-case scenario for septic tanks that must be removed but are out of reach of existing sewer infrastructure. The initial capital cost for the installation of each DWTU is in the range of $12,000-15,000. Instead of a “tap fee” and “impact fee,” the property owner may be asked to provide an analogous “connection fee” in a comparable range of $2,500 to $5,000. But unlike conventional sewer, each new connection does not reduce the remaining treatment capacity at the central plant. So, the entire “connection fee” can help offset the cost of the treatment unit. Assuming a property owner with a septic tank is willing and able to cover the initial fee, there are no other adverse factors to consider. This type of program can be offered on a first-come, first-served basis, utilizing public funding assistance to offset the initial property owner costs, or it could be mandated for certain triggering events, such as the failure of a drainfield or the sale of a home. Once connected to distributed sewer, the property owner will have no responsibilities other than to pay a recurring sewer bill, which averages approximately $50 per month. As a result, the utility service experience and cost are indistinguishable from being physically connected to a central sewer collection system.
Other factors to consider with this programmatic approach include: (1) Nitrogen removal performance is between 80%-90%, which meets or exceeds “secondary wastewater treatment standards” at domestic wastewater treatment facilities; (2) The systems are continuously monitored, and any needed repairs can be performed without property owner involvement or impact; (3) With one DWTS permit covering the entire jurisdiction of the permit holder and potentially tens of thousands of DWTUs, the regulatory/administrative overhead is extremely low; and (4) the lack of common collection system to finance means no need for mandatory participation and the associated social costs. These factors, along with the comparable up-front and recurring costs to the participating property owner, are likely to result in rapid acceptance of the model, including in otherwise impossible to reach locations such as barrier islands, remote springs, or canal front homes miles away from the closest sewer line.