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 roof hatches 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 of the floating roof through roof hatches. 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 of the 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 CFR Part 60. (commenters 1,2) 

The Department agrees and is amending the rule to reflect the New Source Performance 

requirement which allows ten years between complete inspections. 

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3. Chapter 111 amendments would mandate emptying and degassing the tanks to 

perform the complete inspection, whereas federal requirements do not. Under the federal 

requirements, internal inspections of the internal floating roof can be performed from atop 

the floating roof while the tank remains in service, under certain conditions. 

(commenter 1) 
The Department agrees that inspections can be done without degassing the tank, but 

inspections must be conducted so there is visual access to all deck 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 of above-ground storage tanks (AST). By prohibiting complete inspections 

during 50% of the 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 of Chapter 600 and the 

Department to address the concern for reducing VOC emissions on high ozone days, the 

prohibition section has been redrafted. The Department added a prohibition provision 

beginning January 1, 2000 that prohibits emptying and degassing tanks on those days 

for which the Department has issued an ozone health warning. Beginning January 1, 

2004, tank emptying and degassing for the purpose of performing a complete inspection 

is prohibited between June 1 and August 31 of each year. The January 1, 2004 date 

ties in with Chapter 600 provisions which require cert(lin tanks to be inspected by then, 

therefore many of the tanks will have been inspected, repaired, and upgraded before the 

three-month prohibition becomes effective. 

5. Chapter 600 may require the installation of release 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 of an internal 

liner (a coating, such as epoxy or fiberglass, which is applied to the upper surface of 

the bottom of the 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 approach for prohibition requirements will 

allow industry to comply with the requirements of the proposed Chapter 600 and 

Chapter 111. 

6. The prohibition on the ability to empty and degas an aboveground storage tank 

during the period of June 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 

of the t3.¥. As is currently drafted, the regulation would require the terminal to 

continue with the emergency situation until the prohibition period has passed. 

(commenter 2) 
The Department believes that the rule as drafted does not prohibit emptying and 

degassing tanks for 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. In fact, 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 of time (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 of evacuating the tank for maintenance purposes. (commenters 1 ,2,4) 

The commenter did not provide any data to quantify the emissions and substantiate this 

comment. Emissions from an in-service tank may or may not be greater than emissions 

from degassing a tank and having it remain empty for 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 of the 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 of gasoline storage 

tanks which will be cleaned each year and the relatively few days when the ozone level 

even approaches an unhealthy level, it does not make sense to prohibit the emptying 

and degassing throughout the summer period. (commenter 1) 

Although EPA revoked the 1-hour ozone standard in Maine (including York, 

Cumberland and Sagadahoc counties), on July 16, 1999 Maine monitored three 

exceedances of the old 1-hour ozone standard. The Kennebunkport monitor recorded a 

1-hour maximum ozone level of 126 parts per billion (ppb), the McFarland Hill Monitor · 

(Acadia National Park) recorded a 1-hour maximum ozone level of 125 ppb, and the 

Cadillac Mountain monitor recorded a 1-hour maximum of 127 ppb. The 

Kennebunkport exceedance could have significant program impacts if the 1-hour ozone 

standard is reinstated by EPA*, since this was the fourth such exceedance in three 

years. If this area is once again designated as nonattainmentfor the 1-hour standard, 

Maine will be required to fulfill several outstanding Clean Air Act (CAA) requirements, 

including receiving approval for its 15% Plan and Attainment Demonstrations. 

Prohibitions against emptying and degassing bulk terminal storage tanks could play an 

integral r..ole in receiving EPA approval for these and other CAA requirements. 

While the 8-hour ozone standard has now been remanded back to EPA for further 

consideration, it is our expectation that this health-based standard will soon be 

implemented on a nationwide basis. The Department expects that at least five sites will 

monitor unhealthy ozone air quality under the new standard, and believes that reducing 
local emissions from bulk storage tanks could play an important role in our attainment 

strategy. 

*Due to several recent court decisions, EPA is currently considering reinstatement of 

the 1-hour standard. 

9. Maine recently amended Chapter 119 to require that 7.8 psi RVP gasoline be 

provided in place of RFG 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, but additional controls such as lower RVP 

gasoline and restricting storage tank emissions can only help to further reduce ozone 

levels. Ozone is one of the most widespread pollutants that effects the greatest number 

of people in the State of Maine and the Department believes reducing VOC emissions is 

a priority. 

10. The primary source of ozone pollution in Maine is regional transport from 

upwind areas. Further reduction of volatile organic compound emissions in Maine will 

not provide significant reductions in ozone levels within Maine. EPA's primary focus 

for the prevention of ground level ozone formation is moving to reduction of NOx 

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 ozone problems are due to ozone and ozone 

precursor transport, there is little support for the contention that additional VOC 

controls will not have a significant impact on air quality in Maine. There is a wealth of 

photochemical grid modeling that shows the importance of both NOx and VOC 

emissions to ozone formation, with NOx controls being most effective at reducing longrange transport, and VOC controls having their greatest impact locally. The 

Department believes that the proposal can significantly impact air quality in the areas 

downwind of bulk terminal facilities, and is a cost-effective means of safeguarding 

against 1-hour and 8-hour exceedances. ,• . ,• 

11. Industry has not had the opportunity to review any empirical data quantifying 

the actual impact of tank inspections on air quality standards. Therefore, they are 

unable to determine if the 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 Protection Agency indicates 

that, as an example, degassing a 1501oot diameter tank is estimated to generate 

approximately 3 tons of VOC. 

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