4. Availability of Control Equipment

Comment: Some commenters believe that there will be a 

shortage of control equipment available to meet the proposed 

storage vessel requirements, and recommend revisions to the 

compliance deadline for storage vessels based on a variety of 

considerations, including the availability of control devices, 

lead time needed for manufacturer testing of their combustors to 

be compliant with the NSPS and time needed to install the 

compliant devices.

Response: We agree that it will likely take some time 

beyond the promulgation date of the NSPS for combustor 

manufacturers to have control devices constructed, tested, 

documented and available for operators to install in efforts to 

comply with the storage vessel requirements of the NSPS. Under 

the final rule, operators are not required to conduct individual 

performance tests on combustors installed in the field if the 

combustor manufacturer tests and documents for the owner or 

operator that the model achieves a control efficiency of 95.0 

percent. The time required for testing and documentation is 

often longer than for a single model when manufacturers provide 

multiple models for varying applications based on capacity. We 

believe this testing and documentation program would require an 

“adjustment period” for manufacturers to be ready to supply the 

operators with the correct equipment they need.
We evaluated whether controls other than combustors would 

be available during this adjustment period. Although vapor 

recovery units can provide 95.0 percent control for storage 

vessels and are one means of meeting the storage vessel 

standards in the NSPS, VRUs cannot be used in every situation. 

For example, storage vessels located remotely where there is no 

available electrical service may not be able to be controlled 

using VRUs. In addition, storage vessels with low concentration 

emission streams or fluctuating emissions may not be amenable to 

control by VRUs.

In light of the above, we conclude that there is no BSER 

for storage vessel affected sources during the first year after 

promulgation, which we believe is appropriate for the adjustment 

period mentioned above. At the end of this adjustment period, 

we believe owners and operators should have no problem securing 

control devices that are manufacturer-tested and have 

appropriate documentation for determining control efficiency. 

Accordingly, the final rule provides for a one-year delay 

beginning [INSERT DATE OF PUBLICATION IN FEDERAL REGISTER] 

before the 95.0 percent control requirement is effective.

With regard to providing time for operators to establish 

the need for controls and install them where called for, the EPA 

agrees that some lag time may be needed after initial start-up 

for the owner or operator to determine the long-term production 
level of a well and to procure the appropriate control 

equipment. EPA evaluated the approach taken in the Wyoming rules 

for new sources, which allows from 30 to 90 days for a source to 

achieve compliance, depending on the area of the state. Wyoming 

allows only 30 days in ozone nonattainment areas, 60 days for 

concentrated development areas or 90 days elsewhere in the 

state. EPA believes that taking a similar approach in this NSPS 

is appropriate for new storage vessels at wells sites with no 

wells already in production.

However, for replacement storage vessels or additional 

storage vessels at well sites with one or more wells already in 

production, we believe the operator already should have 

information on liquid composition and throughput. This 

information would allow estimation of VOC emissions to determine 

applicability of control requirements and for acquisition and 

installation of a control device concurrent with the replacement 

or additional storage vessel being installed. In the final rule, 

for storage vessels constructed, modified or reconstructed at 

well sites with no well already in production, we have provided 

for a 30-day period for throughput to stabilize and for the 

operator to estimate VOC emissions to determine whether a 

control device will be required. If VOC emissions are estimated 

to be at least 6 tpy, the operator is provided an additional 30 

days for the control device to become operational. We believe 
that the Wyoming experience illustrates that this will be 

sufficient time to size and obtain suitable controls.