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EPA Proposes Strict MP&M Effluent Guidelines
by: Mike McGinness
CleanTech, Vol.1, No. 3, Pages: 24-27; March, 2001

Is wastewater treatment in your future?

When the newly proposed final rule for the metal products and machinery (MP&M) point source category under the Clean Water Act (CWA) goes into effect, it just might be. The latest episode in the 12-year saga of MP&M rulemaking was the publication of the newly proposed rule on January 3, 2001. This version could drastically affect the way the majority of cleaning operations in the United States conduct business. The aim of the Environmental Protection Agency (EPA) is to reduce the discharge of conventional pollutants by at least 115 million pounds per year, priority pollutants by 12 million pounds per year, and nonconventional metal and organic pollutants by 43 million pounds per year.

The EPA estimates that almost 90,000 facilities in the United States fall into the MP&M point source category. However, the EPA is proposing to cover only approximately 10,000      facilities with the new rule.

New Versus Existing Sources

The latest version of the rule is divided into two categories: (1) effluent limitations for new sources; and (2) pretreatment standards for existing sources. The final rule is scheduled to go into effect by December 2002, at which time all new sources will have to comply with the new source effluent limitations. Existing sources will have three years after the final rule goes into effect to comply with pretreatment standards.

The guidelines cover a broad range of facilities, including some not previously covered by either electroplating or metal finishing pretreatment standards. In general, facilities that manufacture, rebuild, and maintain metal parts, products, or machines will be covered by the rule. Surveys indicate that approximately 89,000 MP&M facilities would fall into the MP&M point source category. Of these, approximately 26,000 either do not use or discharge wastewater, or use a contract hauler for their wastewater disposal.  

The remaining 62,752 facilities, or 71 percent of MP&M facilities, are wastewater-discharging facilities that could be subject to the regulation. These facilities include 57,948 indirect and 4,804 direct dischargers. ("Indirect" signifies discharge to a publicly owned treatment works [POTW]. "Direct" signifies discharge directly to rivers/streams under a National Pollution Discharge Elimination System [NPDES] or equivalent permit.)

Pollutant Terminology and Parameters
"New source" is a new or existing facility that is about to undergo process changes that are not classified as maintenance. "Performance standards" are standards for performance for pollution control devices. Abbreviations of pollutant discharge parameters are shown in Table 1.

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A Brief History
The EPA published an Effluent Guidelines Plan in the January 2, 1990, issue of the Federal Register (55 FR 80), in which schedules were established for developing new and revised effluent guidelines for several industry categories commonly referred to as Categorical Pretreatment Standards of the CWA. One of the industries for which the agency established a new schedule and category was the Machinery Manufacturing and Rebuilding Category. (The name was changed to Metal Products and Machinery in 1992.)

The Natural Resources Defense Council, Inc. (NRDC) and Public Citizen, Inc. challenged the Effluent Guidelines Plan in a suit filed in the U.S. District Court for the District of Columbia (NRDC et al v. Reilly, Civ. No. 89-2980). The plaintiffs charged that the EPA’s plan did not meet the requirements of section 304(m) of the CWA. A Consent Decree in this litigation was entered by the court on January 31, 1992. The terms of the Consent Decree were reflected in the Effluent Guidelines Plan published on September 8, 1992 (57 FR 41000). This plan required that the EPA propose effluent guidelines for the MP&M category by November 1994 and take final action on these effluent guidelines by May 1996.

An Effluent Guidelines Plan was published on August 26, 1994 (59 FR 44235). The EPA filed a motion with the court on September 28, 1994, requesting an extension until March 31, 1995, for the EPA administrator to sign the proposed regulation and a subsequent four-month extension for signature of the final regulation in September 1996. On May 30, 1995, the EPA published a proposal on effluent limitations guidelines, pretreatment standards, and new source performance standards for MP&M, referred to as Phase I or the 1995 proposal.

The EPA’s original intention was to handle the proposed regulation in two phases, based on industrial sector. The agency planned to propose a rule for Phase II sectors three years after Phase I. Public comment during Phase I, however, played a role in the EPA’s decision to combine both phases of regulation into one proposal (the 2001 proposal), which will completely replace the 1995 proposal.

Under the proposed MP&M Phase I regulation, an estimated 1,895 direct and 8,706 indirect discharging facilities were to be required to obtain permits. Typical MP&M unit operations were to include any one or more of 48 categories and numerous suboperations within those. In addition to wastewater that was generated from these operations, associated rinses and water-discharging air pollution control devices were also to be included. Wastewater from noncontact, nondestructive testing was also included.

Significant Changes

The schedule for the MP&M rulemaking is included in a new consent decree between the EPA and the NRDC. Although effluent limitations are based on specific process or treatment technologies to control pollutant discharges, there are no requirements to use a specific technology. Individual facilities may meet the requirements by adopting any combination of treatment technologies, practices, and processes that best suit their needs while meeting the discharge limits.

According to the EPA, this rule is expected to reduce the discharge of pollutants that have serious environmental impacts, including pollutants that kill or impair fish and other aquatic organisms; cause health problems through contaminated water, fish, or shellfish; or that degrade aquatic ecosystems. This would include substances that do not readily biodegrade, those that are not removed by POTWs, and those that would pass untreated into U.S. waters even if pretreated at a POTW. It also includes heavy metals that if removed at the POTW would render the sludge toxic and no longer recyclable as fertilizer.

The rule would establish technology-based effluent limitations and pretreatment standards for wastewater discharges for new and existing facilities engaged in manufacturing, rebuilding, or maintenance of metal parts, products, or machines to be used in one of the following 18 industrial sectors: aerospace; aircraft; bus and truck; electronic equipment; hardware; household equipment; instruments; job shops; mobile industrial equipment; motor vehicle; office machine; ordnance; precious metals and jewelry; printed wiring boards; railroad; ships and boats; stationary industrial equipment; and miscellaneous metal products.

For the proposed rule, the EPA reviewed these 18 industrial sectors and divided the MP&M      industrial category into eight subcategories: general metals; metal finishing job shops; printed wiring boards; nonchromium anodizing; steel forming and finishing; oily wastes; railroad line maintenance; and shipbuilding dry docks.

The majority of cleaning facilities would fall in either the general metals or oily subcategories. The EPA has proposed low-flow exclusions for both subcategories. Facilities in the general metals subcategory that discharge less than 1 million gallons a year and facilities in the oily wastes subcategory that discharge less than 2 million gallons a year would not be regulated by the MP&M rule. The EPA states that these low-flow exclusions will exclude more than 50,000 facilities from the proposed rule.


One of the most significant changes to the proposed MP&M rule is the deletion of iron and aluminum from the list of regulated metals with discharge limits for flows to POTWs. They      were removed from the list thanks to an outcry from the POTWs, who use aluminum and iron salts to aid in wastewater clarification. They advised the EPA that POTW operating costs would increase because they would be forced to buy more iron and aluminum salts to replace what was being removed by the rule. Facilities covered by existing categorical pretreatment rules that are covered under the new MP&M rule will need to comply with the most stringent parts of the overlapping rules. Table 2 shows a comparison of current proposed effluent limits versus the 1995 proposed rule limits.

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Major flaws in the earlier proposed rule seem to have been adequately addressed in the latest proposed rule. Barring any further legal challenges or significant public comments that would require the EPA to rewrite the rule, it is conceivable that the final rule will be very similar. The rule must be signed by December 2002. Indirect dischargers will have three years to comply. Direct dischargers must be in compliance at the issue, re-issue, or modification of their permit.

Ensuring Compliance

Look out for easily overlooked processes in your shop that take place only occasionally. For instance, consider contaminant concentrations in monthly or quarterly cleaner bath dumps versus daily rinse water discharge concentrations. Order of magnitude (10 times) differences in the amount of pollutants in used cleaner baths versus rinses can be a major source of waste treatment system problems. This problem increases as the bath gets older and more contaminated. Chelating agents in the cleaner chemistry that can solublize ionic dissolved heavy metals, resulting in increased metals removal costs, may be a source of trouble. These unsteady state process issues in job shops, batch operations that are done on an odd schedule, such as Friday afternoon shop floor cleaning, once-a-month maintenance procedures, once-a-week batch jobs, versus daily procedures can cause havoc with wastewater treatment systems, which are typically not designed for large fluctuations in feed concentrations.

The EPA predicts that implementation of this rule will result in the closure of some marginal businesses. Therefore, it would seem prudent for every facility to take a much closer look at      the actual rules and determine an action plan and expected costs for their situation. In addition, your comment can affect the regulation (see the Comments sidebar).

Many of the features of the rule are complex and, as a result, beyond the scope of this article. Based on the potential impact this rule may have on your business, it would be wise to contact your industry trade association or the EPA for more details — Michael Ebner, (202) 260-5397, or Shari Barash, (202) 260-7130.

A short public hearing and comment period remains before the EPA’s proposed MP&M rule becomes final. The deadline for submitting comments is May 3, 2001. Comments (identified by docket number W-99-23) may be submitted via e-mail to ASCII, WordPerfect 5/6/7/8/9, and Microsoft Word 97 are acceptable formats for file attachments. If writing, comments (original and three copies) should be mailed to Michael Ebner, Office of Water, Engineering and Analysis Division (4303), U.S. EPA, 1200 Pennsylvania Ave., NW, Washington, D.C. 20460.

The complete proposed MP&M rule can be downloaded from the EPA site at the following      URL address:

About the Author
Mike McGinness is vice president of Technology at EcoShield Environmental Systems (Houston, TX) ( and holds a degree in chemical engineering from the University of Houston. He has 26 years of experience in industrial metal finishing processes and chemistry.

To contact him, call (877) 326-7443.

EcoShield Environmental Systems, Inc. P.O. Box 1476 Houston TX, 77251 USA

Toll Free (877) 326-7443 Fax (877) 326-9090