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April 14, 1994


Ms. Sara Giobbi
Industrial Waste Inspector
Industrial Waste Program
Water Utilities Department
City of San Diego
2799 Caminito Chollas
San Diego, California 92105-5039

Dear Ms. Giobbi:

This is in response to your December 20, 1993, letter in which you asked us to determine whether the sulfide precipitation and settling process at the Merry X-Ray Chemical Corporation facility in San Diego is regulated under the nonferrous metals manufacturing requirements at 40 CFR 421.126. I apologize for the delay in responding to your letter. We conclude that Merry's process is not regulated under 40 CFR Part 421.

Based on the regulatory history, we conclude that the discharge requirements under 40 CFR Part 421 apply only to dischargers engaged in nonferrous metals manufacturing as their primary business. Consequently, the Agency did not intend to apply the secondary silver requirements at Part 421, Subpart L to those facilities that recover silver incidental to their primary business or for the purpose of wastewater treatment. For example, a photo lab large enough to justify an electrolytic recovery unit to meet a silver local limit does not become a secondary silver manufacturer even if the wastewater treatment unit generates a profit.

Subpart L of Part 421 establishes effluent limitations that apply to discharges resulting from the production of silver from secondary silver facilities processing photographic and nonphotographic raw materials. When EPA was developing these requirements we found seven secondary silver plants that were direct dischargers. We also found 26 plants that were indirect dischargers, and 28 plants that were zero dischargers. Of the 26 plants that discharged wastewater, five plants processed only photographic materials, and two processed both types. The average plant age was between 15 and 24 years. The Agency would have found thousands of sources subject to the categorical standard if we had intended this category to cover facilities that use a regulated process incidental to its primary business, or recover silver for the purpose of wastewater treatment.

Merry X-Ray performs precipitation and filtration of silver from photographic solutions. Although these are regulated processes under Part 421, this categorical standard does not apply to Merry X-Ray because the Company's primary business is not the recovery of secondary silver, nor other nonferrous metals manufacturing operations. Merry X-Ray performs precipitation and filtration processes to regenerate photographic fixer solution. The Company's recovery of silver is incidental to its primary business of supplying x-ray film and photochemicals to hospitals and other medical facilities.

It is likely that the company that collects the Merry X-Ray sludge is regulated as a secondary silver manufacturer under 40 CFR Part 421. If the collection company's primary business is nonferrous metals manufacturing including collecting such sludges and other photographic waste and further processing them for the purpose of recovering silver, the collection company would be subject to the categorical standard if it performs one or more of the regulated processes even if its final product is not free metallic silver. For example, assume the collection company performs the following operations:

  • Gathers silver sludges and other waste photographic solutions;
  • Performs sulfide precipitation and filtration to concentrate silver;
  • Discharges the supernatant to the sewer system; and
  • Sells the silver-laden sludge to another company for further processing into free metallic silver.

Under these circumstances the collection company would be subject to the secondary silver requirements at 40 CFR Part 421. In this example, the company's primary business concerns reclaiming silver and the company performs a regulated process from which there is a discharge of process wastewater.

This was an excellent question to bring to our attention. Similar questions have occurred in other parts of the country and we have developed this response after considering information from other EPA Regions and Headquarters. If you have any questions regarding this matter, please call me at (415) 744-1907.

Very truly yours,

L. Keith Silva
Pretreatment Coordinator
cc: Ms. Barbara L. Sharatz
Permits Supervisor
City of San Diego