Changes to Tank Degassing and Cleaning Rules Texas Association of Environmental Professionals

1. Changes to Tank Degassing and Cleaning Rules Texas Association of Environmental Professionals

2. Tank Degassing and Cleaning Rules What are the current requirements? Why were the rules changed? What changed? When do changes take effect? Questions

3. What are the current requirements? 30 TAC Chapter 115 Subchapter F Division 3: Degassing or Cleaning of Stationary, Marine, or Transport Vessels Applicability: Stationary tanks with capacity = one million gallons Transport vessels with capacity = 8,000 gallons Marine vessels with capacity = 420,000 gallons Vapor space partial pressure = 0.5 psia

4. What are the current requirements? Control Requirements: 90% control of vapors No avoidable leaks Must use vapor-tight connections No intentional bypass of vapor control device

5. What are the current requirements? Vapors must be routed to control device until: Partial vapor pressure < 0.5 psia; 19,000 ppm by weight; 34,000 ppm by volume as methane; OR Turnover of at least four vapor space volumes has occurred Vapors can be vented to the atmosphere after any of the above conditions is satisfied

6. Why were the rules changed? Studies have indicated that VOC emissions in HGB area are under-reported in emissions inventories. Remote sensing study results have indicated that degassing emissions are under-reported. Rule changes were made to reduce the previously under-reported emissions.

7. What changed? Eliminated “four turnover” condition for allowing vent to atmosphere Confusion over measurement: must be volume passing through tank vapor space; not measured after combustion control Does not account for presence of residual liquid in the tank

10. What changed? Control degassing vapors until VOC concentration of vapors = 34,000 ppmv as methane, or < 50% of lower explosive limit

11. What changed? Monitor VOC concentration of degassing vapors according to 115.545(11) Allow flexibility in monitoring methods Maintain records to demonstrate that method works for compounds present

12. What changed? Specified monitoring methods: Test Method 21 (40 CFR Part 60, Appendix A) Test Method 18 (40 CFR Part 60, Appendix A) Bag samples Test Method 25A (40 CFR Part 60, Appendix A) Portable hydrocarbon gas analyzer using appropriate detector Lower explosive limit detector calibrated and maintained according to manufacturer's specifications Test Method 21 (40 CFR Part 60, Appendix A); can use average composition to determine instrument response factor Test Method 18 (40 CFR Part 60, Appendix A); can use only one bag sample Bag samples Test Method 25A (40 CFR Part 60, Appendix A) Portable hydrocarbon gas analyzer using appropriate detector that is effective in the concentration range being measured, calibrated with compounds of interest, calibrated and maintained according to manufacturer's specifications Lower explosive limit detector calibrated and maintained according to manufacturer's specifications Test Method 21 (40 CFR Part 60, Appendix A); can use average composition to determine instrument response factor Test Method 18 (40 CFR Part 60, Appendix A); can use only one bag sample Bag samples Test Method 25A (40 CFR Part 60, Appendix A) Portable hydrocarbon gas analyzer using appropriate detector that is effective in the concentration range being measured, calibrated with compounds of interest, calibrated and maintained according to manufacturer's specifications Lower explosive limit detector calibrated and maintained according to manufacturer's specifications

13. What changed? Monitoring must continue while vapors are vented to atmosphere: At least once every 12 hours if ventilation is continuous If ventilation ceases for more than 4 hours, concentration must be rechecked before venting to atmosphere Monitoring can be discontinued after five consecutive readings less than 34,000 ppmv or 50% of LEL Test Method 21 (40 CFR Part 60, Appendix A); can use average composition to determine instrument response factor Test Method 18 (40 CFR Part 60, Appendix A); can use only one bag sample Bag samples Test Method 25A (40 CFR Part 60, Appendix A) Portable hydrocarbon gas analyzer using appropriate detector that is effective in the concentration range being measured, calibrated with compounds of interest, calibrated and maintained according to manufacturer's specifications Lower explosive limit detector calibrated and maintained according to manufacturer's specifications Test Method 21 (40 CFR Part 60, Appendix A); can use average composition to determine instrument response factor Test Method 18 (40 CFR Part 60, Appendix A); can use only one bag sample Bag samples Test Method 25A (40 CFR Part 60, Appendix A) Portable hydrocarbon gas analyzer using appropriate detector that is effective in the concentration range being measured, calibrated with compounds of interest, calibrated and maintained according to manufacturer's specifications Lower explosive limit detector calibrated and maintained according to manufacturer's specifications

14. What changed? Require control of vapors for smaller tanks: Capacity = 250,000 with vapor pressure = 0.5 psia Capacity = 75,000 with vapor pressure > 2.6 psia

15. When do changes take effect? Compliance date for new requirements is January 1, 2009

16. For more information Teresa S. Hurley, P.E. TCEQ Air Quality Planning Section 512-239-5316 thurley@tceq.state.tx.us