Studies and inspection observations on tank emissions routed to control device:

• In Sep. 2015 EPA issued a compliance alert on this topic that is full of descriptive concrete design and O&M considerations to ensure tank emission make it to their intended control device: EPA Observes Emissions from Controlled Storage Vessels at Onshore Oil and Natural Gas Production Facilities September 2015. 
• Storage Tank Emissions Pilot Project (STEPP): Fugitive Organic Ccompound Emissions From Liquid Storage Tanks In The Uinta Basin Final Report to The Utah State Legislature July 17, 2017. USU, TriCounty Health Dept, UDAQ. [454 sites surveyed, 39% of sites with controlled tanks emitting before control device]
• Hydrocarbon Emission Detection Survey of Uinta Basin Oil and Gas Wells. November 2018 Bingham Research Center, Utah State University [517 sites surveyed, 31% of sites with controlled tanks emitting before control device]
• Aerial Surveys of Elevated Hydrocarbon Emissions from Oil and Gas Production Sites, Environmental Science and Technology, 2016, 50 (9), pp 4877-4886, publication date April 5, 2016. Over 90% of almost 500 detected sources were from tank vents and hatches. Although tank emissions may be partially attributable to flash gas, observed frequencies in most basins exceed those expected if emissions were effectively captured and controlled, demonstrating that tank emission control systems commonly underperform. Although this study does not delineate controlled tanks from uncontrolled, one could make educated guesses about this. For example, in the Bakken (one of the 7 basins flown over) all the shale oil development would have controlled tanks due to the high production volumes, high tank emissions, and State and FIP regulations in place.
• EPA region 8 inspection findings – R8 first started in Colorado’s DJ Basin (an ozone nonattainment area) by looking at a large enough sample size of a company’s wellpads to ascertain frequency of occurrence where OGI observed tank emissions not making it to the intended control device. We then approach the company with our findings and have settled for design and O&M mitigation at their entire fleet of wellpads in the field/basin. We have done similarly in the Bakken as well.
  • CO – Four joint EPA/CO cases completed or underway with a range of 18%-63% wellpads with controlled tanks and OGI observations of tank emissions not making it to control device. CO has continued this approach with other companies on their own.
  • ND – Five EPA cases completed or underway with a range of 36%-90% wellpads with controlled tanks and OGI observations of tank emissions not making it to control device. EPA addresses Indian country in a similar approach described above and ND is approaching industry on their own in their own way on state lands.
  • UT – EPA inspections to-date have observed an average of ~47% wellpads with controlled tanks and OGI observations of tank emissions not making it to control device.