Interagency Working Comments on Draft Rule under EO 12866 8/5/2010 

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Below are additional working comments from the interagency review of the draft rule titled, 

“National Emission Standards for Hazardous Air Pollutants for Reciprocating Internal 

Combustion Engines--Existing Stationary Spark Ignition (Gas-Fired).” 

Comments:  

Having followed the recent interagency discussion, we share many of the concerns that have been

raised by SBA and others, specifically:

 The inclusion of rural area sources with limited rationale or supporting documentation.   

 The potentially significant regulatory and cost burden of the RICE SI rule on small business,

marginal wells, and other small oil and gas production facilities.   

 The low cost‐effectiveness of some aspects of the rule.

Potential actions:  

 Exclude rural areas sources.  [As we understand this may be difficult for EPA to accomplish within

the timeframe for issuing the final rule, alternative approaches that  raise area source engine

size thresholds to 750 HP or higher, or that reduce or eliminate work practice, monitoring and

testing requirements could increase the cost‐effectiveness of the rule.]

 Raise area source engine size thresholds to 750 HP or higher, specifically:   

o Establish 750 HP or higher as the threshold for control standards for 4LB and 4RB area

source engines,  

o Establish 750 HP or higher as the threshold for work practices for 4LB and 4RB area

source engines, or alternatively increasing the interval between mandatory

maintenance practices, e.g., 4,230 hours.   

 Revise the MACT floor and associated numeric control standards upward for major and area

source engines to reflect variability in engine design, loads, operating conditions, and

performance.  

 Revise the Floor for 4SLB with uncontrolled engines, rather than controlled engines, to

be consistent with the proposed rule.



Potential benefits:  

 Reduces the complexity and cost of the rule.  

 Addresses the marginal economics and limited technical expertise of marginal well and other

small oil and gas production operations and avoids premature well abandonment.  

 Addresses the difficulty of control retrofits on older engines and emission monitoring and

testing in remote areas.   

Background

The RIA and supporting rule documentation mask the regulatory burden and cost of the rule by

aggregating the universe of affected oil and natural gas facilities, not differentiating between urban and

rural sources, and not fully addressing marginal well economics.   
Interagency Working Comments on Draft Rule under EO 12866 8/5/2010 

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EPA data show that the benefits of regulating area source engines below 750 HP are questionable, and

suggest that in some cases a 1,000 HP cut‐off may be appropriate or that controls other than catalysts

and NSCR may be warranted.   

Revised EPA data (8‐2‐2010) show:  

 The overall cost/effectiveness of the rule for a 500, 750 and 1000 HP 4SRB engine is $93,000,

$68,000, and $56,000 per ton of HAP removed using AP‐42 emission factors.    

 Annual costs of control per ton of HAP removed for a 500 HP engine range from $93,000

(4SRB/NSCR) to $28,000 (4SLB/catalyst) per ton and do not appear cost‐effective.      

 In aggregate, regulating area source engines of 500 to 750 HP may yield relatively small emission

reductions, i.e., 1,200 tons of HAP annually.   

Data provided to EPA by API and INGAA suggest the MACT floor and control standards for 2SLB, 4SLB

and 4SRB major and areas source engines should be markedly higher, accounting for variability in

engine design, loads, operating conditions, and performance.  

For engines in remote locations, increases in HAPs and CO2 for service vehicles should be included in the

RIA.