Document ID: EPA-HQ-OAR-2008-0708-0579
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2010-10-19T04:00Z

----- Forwarded by Melanie King/RTP/USEPA/US on 10/19/2010 10:04 AM
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  |Melanie King/RTP/USEPA/US                                                                                                                 
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  |"Holmstead, Jeff" <Jeff.Holmstead@bgllp.com>                                                                                              
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  |Mike.Wasson@Exterran.com, "Rentz, Rebecca" <Rebecca.Rentz@bgllp.com>, 
RobertJ Wayland/RTP/USEPA/US@EPA, Michael Horowitz/DC/USEPA/US@EPA  |
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  |10/18/2010 04:26 PM                                                                                                                       
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  |Re: Concerns about CPMS Requirement                                                                                                       
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Hi Jeff,
Thanks for your note outlining the concerns about the CPMS requirement.
As discussed in the response to comment # 8.1 in the summary of comments and 
responses for the final rule, we believe that these systems are available and 
our cost information is based on quotes from vendors of these systems.  I have 
copied an excerpt from the response below.  Our cost estimates for the final 
rule included not only the equipment cost discussed in the response, but also 
costs for operating and maintaining
the systems.   We believe that we have appropriately accounted for the
CPMS costs in our analysis.  Without more information on the basis for your 
estimates, we cannot determine why they are different from EPA's estimates.  
We believe that the continuous temperature monitoring is necessary to 
demonstrate that the emission limitations are being met on a continuous basis.  
The catalyst inlet temperature is an important determinate of catalytic 
activity and resulting emissions reduction.

Excerpt from response to comment # 8.1:
"EPA disagrees with the commenters’ views that affordable, long-lasting, off-
the-grid systems to measure and record temperatures and pressure differential 
at unmanned, remote locations do not exist. One instrument packager and vendor 
suggested use of his firm’s off-theshelf, battery-operated components. Stand-
alone temperature measurements could be made and recorded using a single 
channel data logger ($129), a temperature sensor ($40), and a copy of software 
($99), while stand-alone pressure differential measurements could be made and 
recorded using a multi-channel data logger ($485), a differential pressure 
sensor ($220), and a copy of software ($89). As the battery life for such 
systems is over 14 months and the data loggers can hold over 43,000 data 
points – more than 14 months of 15 minute readings – each system could operate 
unattended for more than a year. Assuming that an average source has 4 
engines, equipment costs for a stand-alone temperature system would be under 
$200 per point, while equipment costs for a stand-alone pressure differential 
system would be under $370 per point. Of course, these equipment costs could 
be further reduced by consolidating the number of data loggers. Given that 
off-the-shelf equipment is available and that plant personnel are expected to 
visit each remote site at least once per year, when the data loggers could be 
downloaded or swapped out, we find no barriers for measuring and recording 15-
minute temperature and pressure differential data at remote sites."

Melanie King
Energy Strategies Group
Sector Policies and Programs Division
Office of Air Quality Planning and Standards U.S. Environmental Protection 
Agency

Mail Code D243-01
RTP, NC  27711

Phone:  (919) 541-2469
Fax:       (919) 541-5450
king.melanie@epa.gov

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  |"Holmstead, Jeff" <Jeff.Holmstead@bgllp.com>                                                                                              
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  |RobertJ Wayland/RTP/USEPA/US@EPA                                                                                                          
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  |Melanie King/RTP/USEPA/US@EPA, "Rentz, Rebecca" <Rebecca.Rentz@bgllp.com>, 
<Mike.Wasson@Exterran.com>                                     |
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  |10/15/2010 05:42 PM                                                                                                                       
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  |Concerns about CPMS Requirement                                                                                                           
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Bob,

Sorry for the delay in getting back to you with more information about the 
requirement for continuous parametric monitoring systems (CPMS) on 4SRB and 
4SLB RICE > 500 hp.  As I mentioned, we had not really focused on this issue 
before the rule came out because the table in the proposal seemed to suggest 
that CPMS would not be required at area sources.

Over the last couple months, the Exterran folks have spent a lot of time and 
effort (including meetings with CPMS vendors) trying to understand what this 
requirement would actually mean for their fleet.  They didn’t want to go back 
to you and Melanie unless it was a big issue for them, but they really believe 
that the CPMS requirement for >500 hp engines at area sources will be much 
more costly than EPA has estimated – quite a bit more expensive than actually 
installing and operating catalytic controls on the engines.  They also point 
out that the rule already includes 2 other compliance assurance mechanisms 
that they believe will be more effective than CPMS, and that the CPMS 
requirement won’t really accomplish anything in terms of reducing emissions.

It looks like the full cost of CPMS installation and operation is not 
reflected in the Agency’s cost assessments for 4SRB and 4SLB > 500 hp at area 
sources.  EPA has estimated that the cost of the CPMS requirement is about 
$568 per engine.  Based on everything we have seen (including meetings to seek 
pricing from vendors), the actual cost for Exterran to purchase and install 
CPMS will be in the range of $6,000 - $8,000 per engine.  But this is not the 
full cost – especially for engines at area sources, which are generally 
located in remote areas.  On top of the initial cost, Exterran estimates that 
the annual operating costs (primarily for gathering, reviewing and processing 
the raw CPMS data) will be in the range of $9,000 - $13,000 per engine.  The 
biggest part of this cost is for the time it will take to review the CPMS data 
and match it up with operating events to explain the frequent temperature 
variations that will occur at virtually all their engines.

Using our best estimates of the cost of CPMS requirement (including 
installation and ongoing operation), we believe that the cost per ton of 
formaldehyde reduced will be about 3 times higher than the estimates in the 
final rule for both 4SLB and 4SRB > 500 hp at area sources.  Our estimate (and 
we can provide you with a lot of backup data and analysis) is that it will 
likely be more than $89,000 per ton of formaldehyde reduced for 4SLBs and 
about $320,000 for 4SRBs.

Our technical folks also believe that CPMS is unlikely to achieve any 
additional emission reductions because it is just one of three compliance 
assurance provisions in the rule.  CPMS measures the catalyst inlet 
temperature and is one indicator of catalyst performance but not the most 
relevant one.  They believe that the required monthly measurement of 
differential pressure across a catalyst is actually a better indicator for 
catalyst performance because it will show whether a catalyst is plugged (as 
indicated by high pressure differential) or has been blown out by an engine 
backfire (as indicated by low pressure differential).  In addition to the 
monthly measurement of pressure differential, the ZZZZ performance-testing 
requirement is another compliance assurance mechanism.  Given the additional 
cost and technical challenges associated with installing CPMS at area sources, 
we really don’t believe that CMPS is warranted for these engines.

Although CPMS provides a near continuous measurement of inlet temperature, 
operators will still need to go out and gather the data periodically and then 
review it against past operating events.  Thus, CPMS will not identify 
potential catalyst problems any sooner than the monthly measurement of 
pressure differential.  In place of CPMS data collection (and associated 
retroactive data review), we believe that regular temperature checks, together 
with the required pressure readings and performance tests, makes much more 
sense for the thousands of unmanned area sources.  This approach would ensure 
regular on-the-spot checks and immediate maintenance actions, as opposed to 
the retroactive data analysis that would be conducted for each semi-annual 
report submittal.  Regular manual collection of temperature and pressure 
differential would give a better indication of compliance by allowing the 
operator to review both measures at the same time and then implement any 
necessary maintenance actions immediately at the site.

Again, I am sorry we were not able to get this information to you sooner, but 
we wanted to be sure that we really understood these issues before raising 
them to you.  Please shoot me a message or give me a call
if you have any questions.   202-828-5852.

Jeff