REGION IX
75 Hawthorne Street
San Francisco, CA 94105-3901

Mail Code W-5-2

March 13, 1995

Dear Mr. Hart:

In your letter of March 6, 1995 to Jacqueline Ríos of my staff you described the acid cleaning process performed at the Special Products Division at Carpenter Technology's San Diego facility ("Carpenter Technology") and requested that EPA review the process to determine if the facility is covered by categorical pretreatment standards. We disagree with your conclusion that the process is regulated solely by local limits established by San Diego. The process described in your letter is a chemical etching operation rather than a cleaning operation and the process is therefore regulated by the metal finishing standards at 40 CFR 433.

In your letter, you stated that "...Ms. Sharatz also advised us that EPA believes the categorical pretreatment standards at 40 CFR 433 (Metal Finishing) are applicable to stainless steel acid cleaning operations which are considered by EPA to be chemical etching and bright dipping." In Carpenter Technology's description of the process, you indicated that "The purpose of the acid cleaning process is to remove oxide from the surface of the steel that occurs as a result of the annealing process." Carpenter Technology argues that the acid cleaning process is not bright dipping. While the acid cleaning operation may not fit the common usage of the terms "chemical etching and milling", EPA concludes that the process is nevertheless covered by the Metal Finishing regulation, regardless of the terminology used to describe the operation.

When the Development Document was written, EPA had planned to regulate all of the 46 processes which are covered by the Metal Finishing category and therefore did not fully distinguish the differences between the processes. After the final Metal Finishing regulations were adopted which tied coverage under the category to the six primary metal finishing processes, EPA has had to clarify the applicability of the regulation.

The purpose of cleaning operations as defined in the Development Document is to remove the bulk of soils (oil and dirt) prior to phosphating, electroplating, painting, pre and post penetrant inspection, burnishing and polishing, or after any other operation that produces an oil bearing part (See pg. V-41 of Development Document). The Development Document does not fully distinguish the difference between acid cleaning as cleaning and acid cleaning as etching.

Although acid cleaning (also referred to as pickling, acid dipping, descaling, or desmutting) is referenced in the Development Document under the description of cleaning (on pages III-26 and V-42), EPA has determined that the removal of tarnish and scale using an acid is chemical etching rather than cleaning. Including the removal of oxides in addition to oil and dirt in the description of acid cleaning conflicts with the intent of the metal finishing regulations. When acid removes oxides in addition to the oil and dirt, EPA interprets the operation as an etching operation. The metal finishing regulation intended for processes which dissolve and remove metal (including metal oxides formed on the surface) from a work surface using acids to be covered as primary metal finishing operations. For this reason, bright dip operations are included as a primary metal finishing operation. If an acid removes any basis material or metal oxides the operation is etching and is covered as a primary metal finishing operation.

Under 40 CFR 433.10(a) the metal finishing regulations ". . . apply to plants that perform . . ." electroplating, electroless plating, anodizing, coating, chemical etching, or printed circuit board manufacturing and extend to other operations on-site associated with metal finishing specifically listed in 40 CFR 433.10(a). The metal finishing standards apply to the entire facility including the discharges from the 40 associated operations listed at 40 CFR 433.10(a). Carpenter Technology qualifies as a metal finisher because the chemical etching process is a metal finishing operation. When a facility performs one of the metal finishing operations, the standards apply to the entire facility even when the electroplating, electroless plating, anodizing, coating, chemical etching, or printed circuit board manufacturing process and/or associated rinse does not discharge wastewater to the sewer system. Discharges from the primary as well as the associated metal finishing operations at Carpenter Technology are subject to the metal finishing standards at 40 CFR 433.

In your letter, you also stated that the total acid-cleaning flow is about 250 to 500 gallons per operating day and that "Given the low volume of the discharge and the current controls we have in place, there is hardly any chance that discharges from the Special Products Division could cause interference with POTW operations or pass through of pollutants at the POTW." In the preamble for the metal finishing regulations (48 FR 32478) in response to a comment that there should be a small plant exemption from the Metal Finishing regulations, the Agency responded that there would be no significant economic impacts if small plants were covered by the metal finishing standards and that a small facility exemption was not warranted.

Local limits are intended to prevent pass through and interference at POTWs and may be more or less stringent than categorical standards depending on the POTW. Categorical standards, which apply to Carpenter Technology for cadmium, chromium, copper, lead, nickel, silver, zinc, cyanide, and toxic organics, are effluent limitations reflecting the ability of best available technology economically achievable to reduce effluent discharges for designated industry categories such as metal finishers. Federal Categorical pretreatment standards are developed based on technology designed to meet standards in 99 out of 100 samples. The treatment technology on which the metal finishing standards are based are segregation of wastestreams, oily waste removal, recovery of precious metals, dechelation of complex metal wastestreams, destruction of cyanide-bearing wastestreams using chlorine, reduction of chromium wastestreams from the hexavalent to the trivalent state, flocculation, chemical precipitation and settling, and source control measures to reduce toxic organic discharge.

If you have any further questions regarding this matter, please do not hesitate to call Jacqueline Ríos at (415) 744-1908.

Sincerely,

Alexis Strauss, Acting Director Water Management Division

Attachment (March 6, 1995 letter from Michael Hart to Jacqueline Ríos)

FEDERAL EXPRESS March 6, 1995

Dear Ms. Rios:

On February 17, 1995, we were advised by Ms. Barbara Sharatz of the City of San Diego Metropolitan Wastewater Department that EPA has concurred that categorical pretreatment standards set out at 40 CFR Parts 420 (Iron and Steel), 459 (Photographic Processing), 468 (Copper Forming) and 471 (Non-Ferrous Metals Forming) do not apply to Special Products Division operations. Ms. Sharatz also advised us that EPA believes the categorical pretreatment standards at 40 CFR Part 433 (Metal Finishing) are applicable to stainless steel acid cleaning operations which are considered by EPA to be chemical etching and bright dipping.

We do not agree with your preliminary determination and we request that you reconsider your position based upon the following:

Etching and chemical milling are defined in the Metal Finishing Development Document (EPA 440/1-83/091, June 1993) at page III-25 as follows: "These processes are used to produce specific design configurations and tolerances or surface appearance on parts (or metal-clad plastic in the case of printed circuit boards) by controlled dissolution with chemical reagents or etchants. ... Bright dipping is a specialized form of etching and is used to remove oxide and tarnish from ferrous and non-ferrous materials and is frequently performed just prior to anodizing. Bright dipping can produce a range of surface appearances from bright clean to brilliant depending upon the surface smoothness desired for the finished part."

As described in our recent correspondence to the Metropolitan Wastewater Department, a limited amount of stainless steel tubing is acid cleaned at the Special Products Division. The tubes are annealed in an open-air atmosphere prior to acid cleaning. The purpose of the acid cleaning process is to remove oxide from the surface of the steel that occurs as a result of the annealing process. The tubes are cleaned in an unheated combination acid solution comprised of 30 to 40% nitric acid and 3% hydrofluoric acid. The tubes are dipped into the acid bath in bundles, removed and manually spray-rinsed. Rinse flows are controlled by manual operation of the water sprays used for rinsing. Note that because of the critical surface quality requirements for these products, the acid-cleaned tubes are first spray-rinsed with fresh potable water and then thoroughly spray-rinsed with de-ionized water. We estimate that the total acid-cleaning rinse flow for stainless steel tubes is about 250 - 500 gallons per operating day, depending upon the number of batches acid cleaned per operating day. Stainless steel tubes are not processed every day.

The above process is not utilized to produce specific design configurations and tolerances or surface appearances, but simply to clean the surface of the steel. Our process is precisely defined at page III-26 of the above-referenced Development Document: "Acid cleaning is a process in which a solution of an inorganic (mineral) acid, organic acid, or an acid salt, in combination with a wetting agent or detergent, is employed to remove oil, dirt, or oxide from metal surfaces. Acid cleaning is done with various acid concentrations can be referred to as pickling, acid dipping, descaling, or desmutting. The solution may or may not be heated and can be an immersion or spray operation.

Our acid cleaning process is not bright dipping because we do not perform this process to produce a bright finish and the resulting surface finish is actually a dull matte-type finish, not within the range of surface appearances from bright clean to brilliant, as described in the definition of bright dipping.

On the basis of this review, we conclude that we do not perform Chemical Etching and Milling. We also do not perform any of the other five Metal Finishing operations listed in the applicability section of Part 433 (i.e., Electroplating, Electroless Plating, Anodizing, Coating, Printed Circuit Board Manufacture). Accordingly, the categorical pretreatment standards at Part 433 do not apply to the operations at the Special Products Division. Also, because no other categorical pretreatment standards apply to operations at the Special Products Division, we should be limited solely by local limits established by the San Diego Metropolitan Wastewater Department pursuant to the National Pretreatment Standards at 40 CFR 403.5 and 403.8.

Also, please be advised that the total process wastewater discharge from the Special Products Division is in the range of 10,000 gallons per day; and, we have installed a physical/chemical wastewater treatment system for treatment of spent acids and acidic and alkaline rinse waters. This system is equivalent to best available technology considered by EPA when developing the national

categorical pretreatment standards. Given the low volume of the discharge and the current controls we have in place, there is hardly any chance that discharges from the Special Products Division could cause interference with POTW operations or pass through of pollutants at the POTW.

We trust you will agree with our conclusions. If you have any questions about our operations please call me at (610) 208-2470 at your earliest convenience. I will call to review this letter with you not later than March 24, 1995. We request that you advise the Metropolitan Wastewater Department of your findings by letter so that we can obtain our renewal permit from the Department as soon as possible. Thank you for your prompt consideration of this matter.