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GENERAL SECTION

EPA Approves Cheaper
Chromium Emission Controls

SUBPART N - NESHAPS STANDARD REVISED
On July 19, 2004, U.S. EPA revised the National Emissions Standard for Hazardous Air Pollutants (NESHAP) for Chromium Emissions from Hard and Decorative Chromium Electroplating and Chromium Anodizing Tanks (See 69 FR 42885). The revisions affect five technical areas of the original 1995 standard:

1. The use of fume suppressants for controlling chromium emissions from hard chromium electroplating tanks;
2. A revised surface tension limit for decorative chromium electroplating tanks when measured with a tensiometer;
3. An alternative emission limit for hard chromium electroplating tanks equipped with enclosing hoods;
4. Revised definitions of chromium electroplating and chromium anodizing tanks; and
5. A revised operating limit for pressure drop monitoring across composite mesh pad (CMP) control systems.

CONTROLLING SURFACE TENSION AS AN ALTERNATIVE
The original 1995 standard set chromium emission limits of 0.03 milligrams per dry standard cubic meter of air (mg/dscm) for existing hard chromium electroplating tanks and half that, 0.015 mg/dscm for new tanks. Data collected by U.S. EPA’s Office of Research and Development (ORD) has indicated that the 0.015 mg/dscm standard can be met when the surface tension in the plating bath is held below 45 dynes per centimeter (dynes/cm) when measured by a stalagmometer and 35 dynes/cm when measured by a tensiometer (which typically yield readings about 20 percent lower than stalagmometers).

Based on this research, the revised NESHAP standard allows operators to meet the surface tension limit as an alternative to the chromium emissions concentration limit.

NEW EMISSION RATE LIMIT FOR ENCLOSED TANKS
Since the 1995 standard was adopted, a number of electroplaters have installed new, state-of-the-art tanks with enclosing hoods. Because of the significantly lower ventilation rates associated with these tanks, it can be difficult to achieve the emission concentration limit, even though the total emissions are well controlled. Recognizing this,
U.S. EPA also included in the new rule an alternative mass emission rate limit for these enclosed tanks.

OTHER REVISIONS
Under the old rule, the definition of affected sources resulted, in at least one case, in a replacement tank being considered as reconstruction and therefore subject to the more stringent emission limits placed on new sources. Because U.S. EPA considers tank replacement to be routine maintenance, they did not intend this result and have therefore indicated they revised the definitions to make it clear that replacement tanks are not new sources.

In addition, the new standard increases the allowable pressure drop across a CMP of ±2 inches of water in recognition that higher pressure drops sometimes occur immediately after the cleaning or replacement of the pads. The site-specific pressure drop range is established during the initial performance test.

For additional information regarding this recent NESHAPS revision or for assistance with other Clean Air Act permitting and compliance issues, please contact Mike Zimmer or Emily Rynders at 513.489.2255 or by email to mpz@paynefirm.com or ear@paynefirm.com. Please also visit our website at www.paynefirm.com.