Mercury Work Group
Phase II Reports >> Hg Management Guidebook

This Guidebook is a product of the Phase II MWRA/MASCO Mercury Work Group, Mercury Management Subcommittee, Mercury Management Plan Subgroup. It can be used as a reference by industrial facility owners in the development of a Mercury Management Plan to solve sewer discharge compliance problems. The plan of action may involve initiation of a source reduction program or enhancement of an existing one, and it may also involve implementation of an industrial wastewater pretreatment strategy.

This Guidebook is intended to help owners of industrial facilities to understand the process of identifying, reducing, and eliminating sources of mercury; provide information on methods for monitoring and treating mercury discharges; and present industry-specific case studies on mercury sources and successful control programs. Several subject areas and processes are highlighted that may help MWRA-permitted sewer dischargers to find solutions to mercury compliance problems.

The Mercury Management Subcommittee of the MWRA/MASCO Mercury Work Group hopes that this Mercury Management Guidebook will be a valuable and practical tool for many facilities, providing insight into the many variables associated with creating and successfully implementing a comprehensive Mercury Management Plan.

Section 3.0 (References) of this document lists sources of additional information on mercury-related issues. More information, or copies of materials referenced in this Guidebook, can be obtained from:

Requests for copies of the reports of the MWRA/MASCO Mercury Work Group should be sent to the MWRA at the above address. Note that the Work Group reports can also be found on the Internet at the following Web-site addresses: http://www.mwra.state.ma.us and http://www.masco.org/mercury.

The reports from Phase II of the Work Group effort provide new and updated information that generally supersede earlier reports. The Phase II reports are as follows:

# Facilities Loadings Subgroup Report - estimated sewer discharge loadings of mercury from five types of facilities discharging to the MWRA sewerage system.

# Pretreatment Guidance Manual - recommended steps for implementing coordinated source reduction, source segregation, and pretreatment including mercury pretreatment.

# Technology Identification Subgroup Report - background and results of a bench-scale feasibility testing project involving six different mercury pretreatment technologies.

# Mercury Management Guidebook - recommended steps for overall management of mercury to reduce and control the mercury concentration of sewer discharges (this document).

In addition, the Work Group has prepared a computerized database called the Mercury Products Database listing approximately 8,000 chemicals used by hospitals and institutions. For about 800 listed products, the Database includes the results of analytical testing for mercury content. The Mercury Products Database can be obtained from the MWRA at the above address and can also be found on the Internet at the following Web-site addresses: http://www.mwra.state.ma.us and http://www.masco.org/mercury.

In areas served by municipal sewers, facilities with industrial wastewater discharges are often required to limit the discharge of toxic, corrosive, or other pollutants into the sewer system and associated sewage treatment facilities. Sewage treatment facilities owned by states and municipalities are known as Publicly Owned Treatment Works (POTW). In the Greater Boston area, the MWRA operates a POTW that serves 43 communities.

In districts served by a POTW, both general and specific discharge limits are usually applied to industrial users of the POTW system. Overall, industrial wastewater sewer discharges must be controlled to prevent:

• Harm or interference with the sewerage system or any POTW treatment process, including sludge use, management, or disposal.

• Passage (pass-through) of untreated pollutants through the POTW that could cause a violation of any federal or state law, permit, or water quality criteria or that could cause any adverse effects on the receiving waters.

• Threat of endangerment of the life, health, or welfare of any person or persons (including sewer and POTW workers) or of the public health, safety, or welfare, or the environment, or public property (including fire or explosion hazards in sewers or the POTW).¹

As part of the EPA National Pollution Discharge Elimination System (NPDES) permit system, the operator of a POTW is required to evaluate periodically the specific discharge limits it sets for industrial wastewater relative to existing federal and state environmental quality criteria. These specific industrial discharge limits are called Local Limits. To conform with federal and state guidelines, an evaluation of Local Limits must be based upon a substantial body of analytical data including the quantity and quality of industrial and nonindustrial sewer discharges, treatment plant pollutant removal rates, and residual biosolids (sludge).

In the Boston Metropolitan Sewerage Service Area, the MWRA found in its Local Limits evaluations that specific industrial discharge limits were required for several heavy metals and organic compounds and, furthermore, that prohibitions were required for industrial discharges of pesticides, polychlorinated biphenyls, phenanthrene, and mercury. The applicable Local Limits and discharge prohibitions are included in the MWRA Sewer Use Regulations (360 CMR 10.000) and appear as requirements in MWRA sewer use permits issued to industrial dischargers.

To enforce the mercury prohibition, the MWRA developed an enforcement limit where an industrial discharge would be considered a violation if a representative sample had a mercury concentration of more than 1.0 microgram per liter (�g/L).²  The basis for this 1.0 �g/L (ppb) enforcement limit is a recognition that the method detection limit of EPA Method 245.1 for mercury in wastewater samples was typically 0.2 �g/L (ppb). Thus, a wastewater sample measuring greater than 1.0 �g/L (ppb), which is five times the typical method detection limit, would certainly contain the prohibited mercury.

To come into compliance with MWRA Local Limits including the prohibitions, each permitted industrial facility should begin by studying its proposed or existing process wastewater discharges to find the most economical and practical approaches to meet the Limits. For some facilities, compliance with all Local Limits may be achieved by implementation of a source reduction program. For other facilities, source reduction combined with source segregation and pretreatment, or pretreatment alone, may be required. Often, the lowest capital and operating costs for a new pretreatment system can be realized when the system at each discharge point is integrated with source reduction, source segregation, and other aspects of facilities management.

In March 1997, the MWRA announced its intentions to implement a new Mercury Enforcement Plan, known as the Safe Harbor Program, effective July 1997. The Program reduces enforcement requirements for facilities that show reductions in mercury discharges. Therefore, the Program rewards facilities that continue to reduce their mercury contributions to the sewer system.

To initiate the Program, the MWRA assigned its noncompliant mercury dischargers³  into two groups. Group 1 dischargers consisted of sewer users whose discharges contain 4 �g/L or less of mercury; Group 2 dischargers consisted of sewer users whose discharges contain more than 4 �g/L of mercury. All sewer users, regardless of assigned group, were expected to work actively toward having no greater than 1.0 �g/L (ppb) of mercury in their sewer discharges.

Each of the Group 1 and Group 2 sewer users were issued an enforcement order that outlined the applicable Safe Harbor requirements. Group 2 sewer users had more stringent requirements such as requirements to evaluate, design, install, operate, and improve (if necessary) a full-scale end-of-pipe pretreatment system for mercury. Any facility that operated outside the Safe Harbor Program would be subject to escalating enforcement including monetary penalties. Refer to Appendix G for a copy of the MWRA Safe Harbor Program memorandum.

The MWRA will review its mercury discharge prohibition upon its next Local Limits evaluation that will be done according to EPA requirements. The Local Limits evaluation and report will be completed and submitted to the EPA regional office early in 2000.

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