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Residuals & Biosolids

MassDEP regulates the sale, distribution, and land application of residuals in Massachusetts. It also regulates construction and modification of residuals treatment facilities and residuals landfills.

PFAS in Residuals

Overview

MassDEP regulates the land application of sludge and septage for beneficial purposes under 310 CMR 32.00. This includes:

  • treated biosolids (residuals) produced from sanitary wastewater sludge
  • drinking water treatment facility sludge
  • residuals from industrial facilities
  • short paper fiber

All residuals and sludge products sold, distributed, and land applied for beneficial reuse in Massachusetts are subject to an Approval of Suitability (AOS), which classifies residuals for different uses based on chemical quality and treatment to reduce pathogens. Each approval cannot be renewed for more than five years.

Since August 2020, MassDEP has required quarterly monitoring of per- and polyfluoroalkyl substances (PFAS) in residuals that have an Approval of Suitability (AOS) and are permitted to be reused through land application. This increased frequency in monitoring, which had been required annually since January 2019, was implemented to address the need for more information on PFAS characteristics in residuals.  This data is uploaded to a public portal.

More information

For more information about MassDEP’s regulation of residuals, contact the Residuals Program at massdep.residuals@mass.gov.

PFAS and Residuals Technology and Management Study

In 2024 MassDEP awarded 2 contracts to analyze sludge disposal and reuse capacity in and outside of the Commonwealth.  These contracts are collectively referred to as the PFAS and Residuals Technology and Management Study (“Sludge and Septage Study”). Part 1 focuses on the current and near-term destinations for Massachusetts sludge and septage and was conducted between February and June 2024. Part 2 focuses on the intersection of sludge and PFAS, including how legislative and policy decisions regulating PFAS may affect sludge disposal capacity, and PFAS reduction and destruction technologies.  The Part 2 contract was awarded 5/1/24 with expected completion in early 2025. A stakeholder meeting is expected to occur in Fall 2024, and a final report will be published for both studies.

Part 1 Overview

Part 1 focuses on the current and near-term destinations of Massachusetts sludge.  This includes information surveyed from wastewater treatment plants, sludge disposal facilities, and septage disposal facilities to determine: volume of sludge and septage produced in Massachusetts currently and in 5 years, the cost of sludge/septage disposal currently and in 5 years, and the capacity of sludge/septage disposal options.

Part 1 included the following reports:

Part 2 Overview

Part 2 focuses on the intersection of sludge and PFAS.  It includes PFAS reduction and management technologies for wastewater and sludge, contributions of PFAS into POTWs (Indirect Discharges), PFAS impacts on sludge disposal methods as well as options for POTWs and regulators to consider. 

Final PFAS and Residuals Technology and Management Study Meeting: Parts 1 and 2

MassDEP’s consultants Tighe & Bond and Brown and Caldwell presented a summary of the Sludge Study Parts 1 and 2 on January 31st, 2025, from 9:30 AM - 11:30 AM.

If you have remaining questions after the meeting, please send them via email to MassDEP.NPDES@mass.gov.

Frequently Asked Questions about Residuals

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

Sludge is the solid material in wastewater, either from wastewater treatment plants or on-site septic tanks. Biosolids is sanitary sludge that has been treated to ensure that it can be applied to land as a fertilizer or soil amendment. Residuals is a general term for both sludge and biosolids.

How are biosolids and residuals 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 available for use as fertilizer or soil amendments.

Does the EPA regulate biosolids and residuals?

EPA only regulates the beneficial reuse of biosolids through land application (but not non-sanitary residuals). 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.

More information about land application of biosolids and residuals in Massachusetts 

MassDEP regulations for the Land Application of Sludge and Septage (310 CMR 32.00) require that treated sludge meet the following conditions:

  1. Sampling and Analysis Plan: documents how samples of biosolids or residuals 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.
  3. Land Application Certification: management standards for the spreading and incorporation of biosolids or residuals on a specific parcel of land. Land Application Certificates must be updated each year.

In addition, biosolids and residuals must meet regulated treatment requirements. The type of treatment dictate whether biosolids are categorized as Type I, Type II, or Type III. Available uses for each Type are outlined below:

  • Type I biosolids and residuals may be used as commercial fertilizers and soil conditioners.
  • Type II biosolids and residuals require additional MassDEP permitting in order to be applied to land. Their use is restricted to a specific parcel of land.
  • Type III biosolids and residuals is restricted and any application must be recorded on the deed to the parcel of land on which it is applied.

Additional Resources

Wastewater Treatment Plants that produce biosolids

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

Billerica Public Works
70 Letchworth Ave.
Billerica, MA 01862
978-671-0956

Dartmouth Water Pollution Control Division
759 Russells Mills Road
Dartmouth, MA 02748
508-999-0740

Greater Lawrence Sanitary District
240 Charles Street
North Andover, MA 01845
Email

Hoosac Water Quality District
667 Simonds Road
Williamstown, MA 01267
413-458-5016

Ipswich WWTP
20 Fowlers Lane
Ipswich, MA 01938
978-356-6635

Marlboro East WWTP
860 Boston Post Road
Marlboro, MA 01752
508-624-6920

Massachusetts Water Resources Authority

Mansfield WWTP
6 Park Row
Mansfield, MA 02048
508-261-7330

Nantucket WWTP
188 Madaket Road
Nantucket, MA 02554
508-228-7244

Pepperell WWTP
47 Nashua Road, P.O. Box 319
Pepperell, MA 01463
978-433-9859

Somerset WWTP
116 Walker Street
Somerset, MA 02725
508-646-2838

Springfield WWTP
P.O. Box 995
Springfield, MA 01101
413-787-6269

Southbridge WWTP
P.O. Box 1020
83 Dresser Hill Road
Southbridge, MA 01550
508-764-4927

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