October 15, 2009

Air and Radiation Docket and Information Center Environmental Protection Agency 1200 Pennsylvania Avenue, NW Washington, DC 20460 Attn: Melanie King Submitted via email to king.melanie@epa.gov

Re: Docket ID No. EPA-HQ-OAR-2008-0708

The Bay Area Clean Water Agencies (BACWA) Air Issues and Regulat ions (AIR) Committee appreciates your timely response to our comments in the lette r dated 8/19/2009 on the proposed national emission standards for hazardous air pollutants (NESHAP) for stationary reciprocating internal combustion engines (RICE).

In response to the questions you asked our committee in your 8/20/ 2009 email, our members have provided the following feedback regarding thei r facilities’ operation and maintenance of their on-site RICE engines.

You requested any stack test data that our member agencies may have from their engines. We have included the Source Test Results for RICE engines condu cted and approved by the local air district, the Bay Area Air Quality Management District (BAAQMD). Two of our member agencies have submitted their facilities’ engine te st results for your reference: East Bay Municipal Utility District (EBMUD) and San Jose Water Poll ution Control Plant (WPCP). The test result reports are recent, ranging from 2007 to 2009. P lease note that the engine size and digester gas percentage vary. All of these engine s are cogeneration engines which utilize digester gas, a product of the wastewater treatment process, in combination with natural gas to fuel the engines and recover heat from the e ngines for process heating. Please see Attachment 1 for the stack test data reports. Also, inc luded in Attachment 1 is the testing method used by BAAQMD and cited in the engine testresults for your reference,

Source Test Procedure ST-6.

The overall average carbon monoxide (CO) emission level fromthe attached reports, by

method ST-6 at 15% O 2 , was about 285 ppm. This average is about 60 percent higher than the proposed standard of 177 ppmvd. Therefore, according to the pro posed regulation, these engines would be subject to emission mitigation meas ures or have to be replaced.

In response to your second question regarding our members’ maj or source status, BACWA is comprised of about fifty-five local government agencies of varied jurisdiction sizes throughout the San Francisco Bay Area. BACWA members own and ope rate publicly owned treatment works (POTWs) that serve over 5 million people , treating all domestic,commercial and a significant amount of industrial wastewater. BA CWA members fall into

both regulatory categories: major and area sources. The two agencie s that are submitting stack test data, EBMUD and San Jose WPCP, are both major sources o f criteria pollutants.

In response to your third question regarding requiring work p ractice standards in lieu of an emissions limit, we believe that this is a complicated quest ion. Operating and maintaining the equipment to improve efficiency may reduce levels of HAP s per engine output (mechanical work performed or electricity generated) but may not necessarily result in lowest emission concentrations. In addition, operating condit ions are sometimes driven by the need to simultaneously achieve emission limitations for multiple pollutants. Engine owners and operators must adjust operation and maintenance pro cesses to meet CO and NOx emission limits. To lower the current CO level, operators would need to raise cylinder exhaust temperatures to meet CO limits, but this, in turn, woul d raise the NOx emissions. Achieving compliance for one parameter potentially affects the engine’s ability to meet other emission and/or operational requirements.

The AIR Committee would like to emphasize that our member agenci es’ digester gas fueled RICE engines meet local air emission and operating requiremen ts and that an annual or biannual compliance test would be sufficient to ensure engin e compliance. Continuous monitoring is not only costly and maintenance intensive, but m ost importantly does not yield dramatically different or more accurate results than a less frequent engine emissions

test.

This regulation would potentially discourage the use of valuab le and readily available alternative fuel sources (e.g. digester gas and landfill gas). Ut ilities may find purchasing power from a utility company and flaring digester gas to be a more ec onomical alternative. However, this would have the negative impact of decreasing t he number of renewable energy co-generation systems that are ubiquitous in wastewate r treatment plants. The AIR Committee urges the EPA to consider the overall cost compare d to net environmental benefit of regulating these types of engines, which are already u tilizing a form of alternative

fuel.

To retrofit or replace existing digester gas-fueled engines w ould be a heavy financial burden on our member agencies, all essential public services. The AIR C ommittee would like to echo the comments of the National Association of Clean Water Ag encies (NACWA) that the proposed “low emission levels may be an appropriate requireme nt for new engines, but the cost to retrofit existing engines and install emissions co ntrols has not been justified in the proposed rule.” Also, these measures would likely cost each uti lity millions of dollars; in addition to the investment to retrofit or replace engines, subs tantial investment may be required in cleaning biogas to reduce siloxane and reduced su lfur concentrations. We would support conducting a more detailed cost analysis of the regulat ion as it affects digester engine owners and operators.

A suggestion the AIR Committee would like to make regarding the implementation of the proposed changes to the NESHAP for RICE would be staggered co mpliance deadlines based on facility categories. The AIR Committee requests that E PA consider providing an extended compliance schedule for engines combusting renewab le biogas to provide time for evaluating and implementing cost-effective compliance techn ologies. This lessens the financial impact of these types of regulations on local entitie s. It also allows for our public agencies to form a long-term plan of emission mitigation and to plan ahead and budget for the needed funding to implement these measures.The Air Committee would welcome an EPA-funded early complianc e incentive program

that would supply grants to agencies that meet certain criteria to help fund equipment retrofits or replacement. The projects funded by these grant s would provide the needed data to assist our member agencies in identifying cost effectiv e compliance approaches during these challenging economic times.

Lastly, the AIR Committee would like to clarify that references m ade in our previous letter to total organic carbon (TOC). TOC is more appropriately used whenreferring to carbon content in an aqueous stream. Instead, we would like the EPA to consider the option to use the non-methane hydrocarbons (NMHC) as an alternative surr ogate parameter to carbon monoxide. The committee proposes giving the owners and operat ors the option of meeting a NMHC limit in lieu of meeting a CO limit. This gives flexibi lity to an engine’s owner/operator while still minimizing HAP emissions.

Thank you for your consideration of our comments on the propos ed NESHAPs for RICE. Please contact me at (510) 287-1337 or scheng@ebmud.comif you have any questions about

the AIR Committee’s comments.

Sincerely,

Chair, Air Issues and Regulations Committee