Residuals & Biosolids

What does the Residuals Management Program do?

The Program regulates the beneficial reuse of biosolids in Massachusetts through land application. It also regulates construction and modification of residuals treatment facilities, residuals landfills, and residuals incinerators.

What is the difference between sludge, residuals, and biosolids?

Sludge is the solid material in sanitary wastewater, either from wastewater treatment plants or on-site septic tanks. Biosolids is sludge that has been treated to ensure that it can be safely applied to land as a fertilizer or soil amendment (these are called beneficial reuses). Residuals is a general term for both sludge and biosolids. MassDEP's program that oversees wastewater treatment sludge and biosolids is called the Residuals Management Program.

How are biosolids created?

First, water is removed from the sludge (called "dewatering") with centrifuges, vacuums, drying beds or presses. Then the material is stabilized using one or more treatment methods in order to reduce pathogens and odors and make the biosolids safe for beneficial uses such as fertilizer or soil amendments.

Is all sludge regulated by the Land Application Regulations?

No. Only wastewater treatment residuals that are intended for use as biosolids are subject to MassDEP's Land Application regulations. The incineration or landfilling of wastewater treatment sludge is governed by MassDEP policy and guidance documents.

Does the EPA regulate biosolids?

Yes. EPA also regulates the beneficial reuse of biosolids through land application. EPA's "Regulations for the Use and Disposal of Sludge" (40 CFR Part 503) set pathogen removal and metals standards for biosolids. In some areas, MassDEP's standards are stricter than EPA's, and state regulations and permits also address areas not covered by EPA.

How do we know that biosolids are safe to use?

MassDEP regulations for the Land Application of Sludge and Septage (310 CMR 32.00) ensure that biosolids are safe to use.

Wastewater treatment plants that treat sludge for beneficial use as a biosolids must meet the following conditions:

1. Sampling and Analysis Plan: documents how samples of biosolids will be collected, analyzed, and reported to MassDEP. The plan should describe sample preparation, preservation, and conveyance to certified laboratories.
   Sampling and Analysis Plan approvals do not expire. However, MassDEP must be notified of any change in materials or processes that may affect the sampling locations or the number of samples required.
2. Approval of Suitability: classification of biosolids for different uses, based upon the chemical quality and the degree to which it has been treated to reduce pathogens in the sludge. Approval of Suitability is revisited every two years.
3. Land Application Certification: management standards for the spreading and incorporation of biosolids on a specific parcel of land. Land Application Certificates must be updated each year.

In addition, biosolids must meet strict quality standards for their proposed use:

• Type I biosolids meet very high quality standards and may be used as commercial fertilizers and soil conditioners.
• Type II biosolids meet a lower standard for use than Type I and require additional MassDEP permitting in order to be applied to land. Their use is restricted to a specific parcel of land.
• Type III biosolids have also been treated for pathogen reduction, but typically have more chemicals and metals than Type II biosolids. Use of Type III biosolids is restricted and any application must be recorded on the deed to the parcel of land on which it is applied.

Sludge from industrial wastewater treatment processes is regulated by MassDEP's Bureau of Waste Prevention. 

The following facilities produce biosolids, which may be available to users directly or through retail outlets. For more information, contact the facility directly.

• Blending Policy - Guidance Document 87-1: Utilization of Blended Sludge Compost

  Policy on the utilization of blended sludge compost (compost mixed with sand, peat, or other materials).

• Composting Operations Within Zones of Contribution (Zone II) and Interim Well Head Protection Areas (Interim Zone II)

  Preventing drinking-water contamination from stored sludge and septage.

• Horticultural Use Policy

  Clarifying the allowable use of wastewater-treatment sludge in horticultural operations.

• Hydrogeologic Evaluations - Guidelines

  Hydrogeological evaluations for proposed landfill sites define the geology of the site, groundwater flow paths and rates, design characteristics of the landfill liner, and the location of all proposed groundwater protection and monitoring systems.

• Large Privately Owned Treatment Works - Minimum Contractual Requirements for Reuse or Disposal of Residuals

  Requirements for large publicly-owned treatment works seeking to contract out sludge reuse or disposal.

• Multi-Site/Single Ownership

  Allowing a single application for land application of sludge or septage to cover multiple sites under the same ownership.

• Residuals Landfill Plan Submittal List

  Plan approval application submittal requirements.

• Sludge Analysis Guidelines

  Parameters of a sampling and analysis plan for wastewater treatment sludge and septage.

• Sludge Compost Facilities - Minimum Technical Information Needs for Submittal of Plans and Specifications

  Technical information required for plans and specifications for sludge compost facilities.

• Sludge Disposal - Redundancy Requirements

  Requirements for back-up facilities for wastewater treatment plants that may not be able to dispose of sludge throughout their design life (20 years).

• Sludge Landfills - Closure/Post Closure Requirements

  Procedures and certifications required for closing a residuals landfill.

• Sludge Landfills - Design & Operation

  Parameters for the environmentally safe design and operation of sludge landfills.

• Labeling Requirement and Additional Information Regarding Biosolids Containing Molybdenum

  Due to the potential for molybdenum toxicity in ruminant animals, biosolids containing this element must carry a warning label. November 2016.