SUPPLEMENTAL BASIS STATEMENT

CHAPTER 111

PETROLEUM LIQUID STORAGE VAPOR CONTROL
COMMENTERS

1. William Ward Mobil Corporation

2. Patti Aho Maine Petroleum Association

3. Burton S. Russell Sprague

4. Donald Lee Griffin, Jr. Citgo Petroleum Corporation

1. The routine visual inspection to be conducted through roofhatches every month is above and beyond the most stringent federal New Source Performance Standards for storage tanks regulated under Subpart Kb. The Subpart Kb regulation requires an annual inspection ofthe floating roofthrough roofhatches. The existing Chapter 111 requires semi-annual inspections and should stay that way. (commenter 4)

The monthly inspections have been incorporated into most licenses because this procedure is already being done by industry. This amendment will update the rule to be consistent with license requirements.

2. The rule needs to reflect the requirements ofthe New Source Performance Standards for storage tanks by allowing 10 years between complete inspections if annual visual inspections are performed. Mobil recommends 10 years for all subject tanks since the rule already requires monthly inspections which meet the annual inspection requirements in 40 CFRPart 60. (commenters 1,2)

The Departmentagrees andis amending the rule to reflect the New Source Performance requirementwhich allows tenyears between complete inspections.

,• 3. Chapter 111 amendments wouldmandate emptying and degassing the tanks to perform the complete inspection, whereas federal requirements do not. Under the federal requirements, internal inspections ofthe internal floating roofcan be performed from atop the floating roofwhile the tank remains in service, under certain conditions. (commenter 1)

### The Departmentagrees that inspections can be done withoutdegassing the tank, but inspections mustbe conductedso there is visual access to alldeck components.
4. Chapter 600 regulations currently propose that storage tanks be cleaned on a more frequent schedule than previously required. The June 1 to August 31 prohibition for emptying and degassing tanks will inhibit terminal operators' ability to comply with proposed Chapter 600 amendments regarding cleaning, inspections, repair and upgrading ofabove-ground storage tanks (AST). By prohibiting complete inspections during 50% ofthe construction season, tank upgrade and inspection requirements will be nearly impossible to meet. (commenters 1,2,3,4)


### In order for industry to meet the anticipated requirements ofChapter 600 and the Department to address the concernfor reducing VOC emissions on high ozone days, the prohibition section has been redrafted. The Departmentaddedaprohibitionprovision beginning January 1, 2000 thatprohibits emptying anddegassing tanks on those days for which the Department has issuedan ozone health warning. Beginning January 1, 2004, tank emptying anddegassingfor thepurpose of performing a complete inspection isprohibitedbetween June 1andAugust31 ofeach year. The January 1, 2004 date ties in with Chapter 600provisions which require cert(lin tanks to be inspectedby 

### then, therefore many ofthe tanks will have been inspected, repaired, and upgradedbefore the three-monthprohibition becomes effective.

5. Chapter 600 may require the installation ofrelease prevention barriers or double bottom systems in all large ASTs in the near future. This will result in major construction efforts in the summer. Chapter 600 also encourages the use ofan internal liner (a coating, such as epoxy or fiberglass, which is applied to the upper surface of the bottom ofthe tank following inspection and repair) which must cure at temperatures that only occur during the summer months. The June 1 to August 31 prohibition will make it very difficult to comply with these requirements. (commenters 1,2,3)


### The Department believes that the two-part approachforprohibition requirements will allow industry to comply with the requirements oftheproposed Chapter 600 and Chapter 111.

6. The prohibition onthe ability to empty and degas an aboveground storage tank during the period ofJune 1-August 31 does not provide an exemption for emergencies. For example, an emergency may include a problem with the internal floating roof, or with the vapor recovery control unit, which could require the emptying and degassing ofthe 

## t3.¥. As is currently drafted, the regulation would require the terminal to continue with the emergency situationuntil the prohibitionperiod has passed. (commenter 2)

### The Department believes that the rule as drafteddoes notprohibit emptying and degassing tanksfor emergency situations, but the Department has added language to address the commenter's concern.
7. As drafted, the regulation assumes that many volatile organic compounds (VOC) emitted into the atmosphere are done so during the degassing operation. Infact, most VOC losses from aboveground storage tanks occur from in service standing losses and not from the tank cleaning process. Tank cleaning may actually place a tank out of service for an extended period oftime (up to two months). The emissions from the tank may be greater when it is in service over this period rather than from the single event ofevacuating the tank for maintenance purposes. (commenters 1,2,4)


### The commenterdid notprovide any data to quantify the emissions andsubstantiate this comment. Emissionsfrom an in-service tankmay ormay not be greater than emissions from degassing a tank andhaving it remain emptyfor two months.

8. EPA has recently proposed that the 1-hour ozone standard would cease to apply in the Portland, Maine area since no current violation ofthe 1-hour ozone standard, based on the most recent available data (1996-1998) has been measured. This is a significant achievement and demonstrates that the control measures already adopted both in Maine and in upwind areas have achieved the necessary emission reductions to reduce ground level ozone pollution. Based on the limited number ofgasoline storage tanks which will be cleaned each year and the relatively few days when the ozone level
even approaches anunhealthy level, it does not make sense to prohibit the emptying and degassing throughout the summer period. (commenter 1) 

### Although EPA revoked the 1-hourozone standard in Maine (including York, Cumberland and Sagadahoc counties), on July 16, 1999Maine monitoredthree exceedances ofthe old 1-hour ozone standard. The Kennebunkport monitor recordeda 1-hourmaximum ozone level of126partsperbillion (ppb), the McFarland Hill Monitor · (Acadia National Park) recorded a 1-hourmaximum ozone level of125ppb, and the Cadillac Mountain monitor recorded a 1-hourmaximum of127 ppb. The Kennebunkport exceedance couldhave significantprogram impacts 

### ifthe 1-hourozone standard is reinstated by 

### EPA*, since this was thefourth such exceedance in three years. 

### Ifthis area is once again designatedas nonattainmentfor the 1-hourstandard, Maine will be required tofulfill several outstanding Clean AirAct (CAA) requirements, including receiving approvalfor its 15% Plan andAttainmentDemonstrations. Prohibitions against emptying anddegassing bulk terminal storage tanks couldplay an integral r..ole in receiving EPA approvalfor these and other CAA requirements.
While the 8-hour ozone standardhas now been remanded back to EPAforfurther consideration, it is our expectation that this health-basedstandardwill soon be implementedon a nationwide basis. The Department expects that at leastfive sites will monitor unhealthy ozone air quality under the new standard, andbelieves that reducing

### local emissionsfrom bulkstorage tanks couldplay an important role in ourattainment strategy.
*Due to several recent court decisions, EPA is currently considering reinstatement of the 1-hourstandard.

9. Maine recently amended Chapter 119 to require that 7.8 psi RVP gasoline be provided in place ofRFG in the formerly RFG area. The VOC emissions due to AST cleaning will be less for the 7.8 psi RVP gasoline than for the RFG that it replaced. In 2000, 7.2 psi RVP gasoline will be required and the tank cleaning VOC emissions from it will be more than 10% lower than for RFG (Phase 1). Why is Maine now choosing to prohibit the emptying and degassing during the summer months when the air is already getting cleaner, the state is in attainment for ozone, and the VOC emissions are already being reduced with the replacement gasoline? (commenter 1)


### VOC controls have reduced VOC emissions, butadditional controls such as lowerRVP gasoline and restricting storage tank emissions can only help tofurther reduce ozone levels. Ozone is one ofthe most widespreadpollutants that effects the greatest number of people in the State of Maine and the Departmentbelieves reducing VOC emissions is
apriority.

10. The primary source ofozone pollution in Maine is regional transport from upwind areas. Further reduction ofvolatile organic compound emissions inMaine will not provide significant reductions in ozone levels within Maine. EPA's primary focus for the prevention ofground level ozone formation is moving to reduction ofNOx emissions, not additional VOC controls. Maine's current proposal does not address NOx emissions. EPA simply requires that the current VOC reduction strategies be maintained. ( commenter 1)


### While it is true that the majority of Maine's ozoneproblems are due to ozone and ozone precursortransport, there is little support for the contention thatadditional VOC controls will not have a significant impact on airquality in Maine. There is a wealth of photochemical gridmodeling thatshows the importance of both NOx and VOC emissions to ozoneformation, with NOx controls being most effective at reducing longrange transport, and VOC controls having theirgreatest impact locally. The Department believes that theproposal can significantly impactair quality in the areas downwind of bulk terminalfacilities, and is a cost-effective means of safeguarding against 1-hourand 8-hour exceedances.
,• . ,• 11. Industry has not had the opportunity to review any empirical data quantifying the actual impact oftank inspections on air quality standards. Therefore, they are unable to determine ifthe additional air quality benefits attained will in fact outweigh the increased risks incurred from deferred tank maintenance. ( commenter 4)The data supplied to the Department by the Environmental ProtectionAgency indicates that, as an example, degassing a 1501ootdiameter tank is estimated to generate approximately 3 tons ofVOC.

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