November 2009, Vol. 21, No.11

Small Communities

Small Communities - Solids Management for Cluster and Decentralized Wastewater Systems

Tom Ferrero and Jim Anderson

Recent management trends for wastewater solids within the onsite and distributed wastewater industry present the waste pumper–hauler industry with a mix of positive and negative news. On one hand, the policies and regulatory initiatives of the U.S. Environmental Protection Agency and state and local regulators requiring or encouraging more management of decentralized or cluster systems for small communities should lead to increased business opportunities. On the other hand, many pumpers are struggling with the loss of facilities that will accept their septage for final treatment and dispersal.

Even land application sites in locations that traditionally have approached land application as a beneficial and value-added use of the product have been known to refuse septage. Land application of septage benefits crop production and represents one of the most cost-effective management techniques. The trend for the future seems to be fewer sites for land application. This will be due largely to urbanization of areas surrounding application sites. Most of these sites were in close proximity to the populations served by decentralized treatment systems, and their loss increases haul distances to minimize potential conflicts with residents.

For any small community that relies on decentralized technologies for its wastewater treatment, a management program is essential. Even conventional septic tanks and pump stations require a management program to improve system performance and longevity by removing excess solids and catching problems before they snowball into widespread failures. Community management programs can be good at requiring systems to be inspected and serviced regularly. The emergence of online tracking programs makes it easy for local officials to track which systems are being cared for regularly and which are not.

Where management plans often fall short is in not anticipating the amount of additional septage a management program will generate above the traditional rates. This failure results in providing inadequate septage acceptance, treatment, and dispersal capacity. A key step in proper planning is to document current capacity. If the current capacity is not adequate to satisfy the anticipated rate of septage generation, it may mean delaying plan implementation until sufficient capacity is made available. How to provide additional capacity, if not presently available, should be addressed in the plan. This may involve expanding current facilities or building a septage treatment facility.

Solids Management Options

Depending on the situation within the small community implementing a management plan, there are several options to consider. If the solids management capacity exists at a nearby municipal wastewater treatment plant (WWTP) that accepts septage, the plant should have or establish a manifest system to track the volume of septage loads accepted. The manifest should be a form that documents the origin, time, and location of the on-loaded septage with signatures of the generator, the hauler, and the treatment facility. All three parties should sign the manifest form, and the management entity should receive a copy of the fully executed manifest that confirms where the waste came from and that it was received and managed properly. In addition, the receiving facility should identify at which location or locations within the facility the septage was introduced into the treatment stream.

If the facility does not accept septage, the public popularity of a well-designed management plan may be enough to open the door to acceptance. Locally licensed private haulers should expect to present a good business plan to the community and the WWTP, explaining why acceptance will pay in the long run. Haulers also should offer their expertise to the planners on other relevant issues.

If the local WWTP is not a viable septage receiving option, the community and private haulers can consider other disposal solutions. One is to investigate the cost-effectiveness of nearby facilities that can accept sufficient quantities of septage. The community also could consider establishing a transfer facility to accept and accumulate smaller septage loads and use larger trucks to transfer the septage to the ultimate treatment and dispersal facility. This station could be a stand-alone facility or could be co-located with an existing WWTP.

Another option many private haulers are considering is creating a dedicated septage treatment facility. In the past, this option has been driven by the loss of available land application sites to population increases and farmland losses. The National Association of Wastewater Transporters Inc.  (Amber, Pa.) is encouraging its members to explore such options with their communities.

Such a facility can be established through an individual company or through the formation of a cooperative or partnership between local independent haulers. The community or another public entity also could establish such a facility. It is critical to have a business plan that will show that this is cost-effective for the community over other options. This gives the community better control over where and how the septage is treated.

A third option is to establish a public–private partnership. This option would improve the septage industry acceptance of the management plan and ensure its participation in the facility. This alternative increases the options to obtain funding. It opens the potential for public grants while also opening the door to private capital investment.

The public–private option may have advantages in obtaining the necessary state or county operating permits. For individually owned facilities, obtaining these permits often is a long, difficult process. Often, state regulators and the local community have concerns that the private company or individual may not be able to sustain the facility over the long term and would declare bankruptcy and close the operation, leaving the community with no septage management. Involving many different stakeholders and considering numerous solution options will maximize acceptance of the management plan and minimize problems with the community and with permitting of the facility.

Technology Choices

An essential part of establishing a residuals treatment facility is to determine what technologies will be used and the ultimate fate of the residual solids and liquids generated from treatment. There are numerous options and technologies available for such a facility.

Generally, the technologies selected will involve separating solids from liquids. Depending on the amount of septage generated, this can involve dewatering boxes, belt presses, screw presses, or centrifuges, often with pretreatment chemicals added.

Once the solids are separated, they can be hauled to a landfill, land-applied directly, or composted and used as a soil amendment.

If an industrial discharge permit is obtained from the municipal wastewater authority, the liquids usually can be put directly into a community wastewater collection line and delivered to a WWTP. The liquid can be treated further and spray-irrigated or applied to land for final treatment. Another option, which requires a National Pollutant Discharge Elimination System permit, is discharge through lagoons or other passive processes to a stream.

Final Thoughts

Communities have numerous options to evaluate to see which best fits their situation. Small communities considering a management plan for their decentralized systems should address available septage management capacity. A septage manifest system must be in place as a part of any management plan. The plan should ensure that homeowners adequately maintain their systems and that the septage generated is going to a proper treatment or dispersal facility.

Small communities can find septage management facilities in many forms, including local or regional wastewater treatment plants, a community transfer station to improve the cost-effectiveness of trucking, or a dedicated septage treatment facility. Before finalizing any management plan, the community should look at each of these options from a cost-effectiveness perspective.

 

Tom Ferrero is executive director and Jim Anderson is the education coordinator of the National Association of Wastewater Transporters Inc. (Ambler, Pa.).