Sludge is an organic solid, semi-solid, or liquid by-product of publicly owned treatment works. (For infomation about waste resulting from industrial processes, please contact the Waste Management Program.) Sludge characteristics vary depending on each treatment facility's wastestream and the processes that are used. In general, sludges are composed of water, organic matter, nutrients (such as nitrogen, phosphorus, calcium, and magnesium), and micro-nutrients such as zinc and iron.
Sludges meeting EPA standards for beneficial use are referred to as Biosolids. Like animal wastes, biosolids are a part of the natural cycle of life. They have nutrient and soil-enhancing properties making them a practical choice for a variety of beneficial uses. There has been significant research on the beneficial use of biosolids, and history has demonstrated, in the United States and other regions of the world, high quality biosolids can be beneficial soil additives and plant nutrients when properly applied. Concerns about biosolids relate primarily to the quality of the material and its impact on human health, soil productivity, groundwater, surface water, and adjacent land uses.
To ensure sludges which are used as biosolids are treated and managed in a manner that protects both human health and the environment, Congress directed EPA to develop a comprehensive national Sewage Sludge Program aimed at reducing risks and maximizing the beneficial uses of sludge. In February of 1993, EPA issued its sewage sludge use and disposal regulation, 40 CFR Part 503, commonly referred to as the "503s." For more information, check out EPA's Biosolids Program (Please note, this link will take you out of SD's web site).
As part of EPA's implementation for the 503s, it has developed a permitting program for biosolids to ensure biosolids are beneficially reused in an environmentally safe manner. South Dakota has received delegation of the biosolids permitting program from EPA.
For more information about biosolids reuse and permitting in South Dakota, contact:
Beneficial Uses for Biosolids
As stated above, biosolids have many beneficial uses:
Domestic septage is defined as any liquid or solid material removed from a septic tank, cesspool, portable toilet, Type III marine sanitation device or any similar systems that receives only domestic (non-commercial) septage.
Grease trap residues, grit and screenings, and any domestic septage that is combined with commercial or industrial wastes is not considered domestic septage and is regulated by the department's Waste Management Program. For more information on the disposal of non-domestic septage wastes, please contact the Waste Management Program at (605) 773-3153.
Domestic septage may be disposed of in two different ways in South Dakota. The first option is to take the material to a municipal or private wastewater treatment facility where it can be properly treated. The second option is to beneficially reuse the material by land application at non-public contact sites. A non-public contact site is an area where the potential for public exposure is minimal, such as agricultural fields, forests, or mining reclamation sites.
To protect public health and the environment, there are five main requirements the septage must meet to be land applied. These are:
Pathogens are disease-causing organisms such as bacteria, viruses, and parasites that may be present in septage. The Pathogen Reduction requirement is used to ensure that any potential pathogens in the septage are reduced to a level that is safe for land application. The next requirement the septage hauler has to meet is a Vector Attraction Reduction (VAR) requirement. Vectors are organisms such as mosquitoes, flies, or rodents that can spread disease by carrying and transferring pathogens. The VAR requirement is used to reduce the potential for attracting these disease-carrying vectors.
There are two options for meeting Pathogen and Vector Attraction Reduction requirements. These are:
Lime stabilization involves adding and thoroughly mixing lime (alkali) with each load of septage to ensure that the pH is raised to at least 12 for at least 30 minutes. Usually this requires about 50 lbs of lime per 1,000 gallons of septage. A pH meter must be used to determine whether the pH requirement was met. An operational log and records of the pH readings must be maintained to demonstrate that this requirement has been met for every load that has been land applied.
Septage that is injected into the ground or disked in within 6 hours of application does not have to be lime-stabilized.
The septage must be screened to remove foreign or non-organic objects such as trash or other non-biodegradable objects. Options for this requirement include screening at the site where septage is being collected, screening out the back of the vehicle during land application, or screening using a tank setup. Screenings must be bagged and disposed of at a permitted municipal waste landfill.
The septage must be applied at an agronomic rate. The maximum volume of domestic septage that can be land applied in any year depends on the amount of nitrogen required by the crop grown and expected yield. The following equation is provided in the rules to calculate annual domestic septage application rates:
where: AAR = Annual Application Rate (gallons / acre / year)
N = Nitrogen Required by Crop (lbs)
Site restrictions for land applying domestic septage must be met and include minimum time restrictions for harvesting crops, grazing animals, maximum slope and distances from waterbodies, and restricting public access after land application. Site restrictions include:
When septage is lime stabilized prior to application, the restrictions on animal grazing, turf use, and public access no longer apply to the site. All other site restrictions still apply.
Records of domestic septage disposal must be maintained that show that the domestic septage hauler is meeting all of these requirements. These records must be maintained for a minimum of five (5) years. Required records include:
These rules and regulations became effective in 1993. In 2001, South Dakota was delegated to administer and enforce the septage program. DANR will conduct routine inspections and may require you to submit a copy of your records for further investigation. If you have questions about the requirements in this letter or would like more information, please contact Kyle Doerr at (605) 773-3351.