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August 14, 2013
Amendments issued for O&G storage tanks

Responding to petitions for reconsideration, the EPA has issued significant amendments to provisions contained in the Agency’s April 2012 New Source Performance Standards (NSPS) affecting volatile organic compound (VOC) emissions from storage tanks used in oil and natural gas production and transmission.

Included in the amendments is an alternative emissions limit for tanks from which VOC emissions have declined.  According to the EPA, emissions from tanks covered by the rule decline over time; the alternative allows operators to shift control equipment to higher-emitting tanks.

Generally, the NSPS requires a 95 percent reduction in VOC emissions for storage tanks emitting at least 6 tons per year (tpy) of VOCs and located anywhere along the oil and natural gas production and transmission process.  Storage tanks in refineries and fuel tanks are not subject to the rule. Neither are tanks with enforceable permit limits under federal, state, local, or tribal authority if those limits are less than 6 tons a year.

The rule included the first federal air standards for natural gas wells that are hydraulically fractured, along with requirements for several other sources of pollution in the oil and gas (O&G) industry, which were not previously regulated. 

Petitions for reconsideration of the action came from many O&G associations and a handful of well-known environmental groups.

Major changes

The amendments address the following:

Compliance dates.  The amendments allow different compliance dates for two groups of tanks.  Group 2 tanks are those that come online after April 15, 2013, or within 60 days after start-up.  Group 1 tanks are those constructed between August 23, 2011, and April 12, 2013.
Within 30 days of start-up, owners/operators (O/Os) of Group 2 tanks must estimate the potential to emit (PTE) VOCs from their tanks and determine whether they are subject to the rule.  O/Os of Group 2 tanks have an additional 30 days to control VOC emissions.  O/Os of Group 1 tanks have until October 1, 2013, to estimate their PTE VOCs and determine whether their tanks are subject to the rule and until April 15, 2015, to control emissions as required by the amendments.

Alternative emissions limit.  An O/O may comply with an uncontrolled actual VOC emission rate instead of the 95 percent control requirement where it can be demonstrated that, based on monthly records of actual emission rate for the 12 consecutive months immediately preceding the demonstration, uncontrolled actual VOC emissions from the tank have been below 4 tpy.  The O/O must reevaluate the uncontrolled VOC emissions on a monthly basis.  If emissions increase to or above 4 typ, the 95 percent reduction requirement must be met within  30 days.  However, if the increase was associated with the fracture or refracture of a well supplying the storage tank, the O/O must meet the 95 percent control  limit as soon as liquids from the fractured or refractured well are routed to the tank.

Reports.  O/Os are given an additional 60 days after the end of the compliance period to submit annual reports on well completions, along with information on storage tanks and other equipment constructed or modified during the year. 

Monitoring.The NSPS requires a performance test and a continuous parametric monitoring system to demonstrate compliance with the 95 percent reduction standard.  Industry noted that these requirements are difficult to meet for remote tanks.  In the amendments, the EPA states that it is still evaluating this issue.  While the evaluation continues, the amendments allow streamlined monitoring; specifically, monthly inspections of covers, closed-vent systems, and control devices are required.

Also, while the EPA reviews issues raised in the reconsideration petitions related to field testing protocol requirements, the amendments allow O/Os to use control devices that are designed to reduce VOC emissions by 95 percent.  The Agency expects to address this issue by the end of 2014.

Click here for information about the amendments.

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