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### . ~114 l aFOtE~ MEMORANDUM 

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SUBJECT: Contingency Measures for Ozone and Carbon Monoxide (CO)

Redesignations FROM : TO: 

### UNITEDSTATESENVIRONMENTALPROTECTIONAGENCY

OfficeofAirQualityPlanningandStandards ResearchTrianglePark,NorthCarolina27711

G.T. Helms, Chief Ozone/Carbon Monoxide Programs Branch (MD-15) Air Branch Chief, Regions I-X 

### Several Regions have asked for specific examples of what a contingency plan should contain. In general, a contingency plan should identify the measures that the State will adopt and the-- factors that will determine when the measures will be adopted. An example of this is attached. The attached example is only one approach to the contingency plan; it is not the only approach. If you have any further questions concerning this subject, please contact Laurel Schultz at (919) 541-5511 . 

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Example of Ozone Contingency Plan Provisions: 

### The following provisions might be included in a contingency plan: 1) Inclusion of several potential scenarios that could trigger implementation of the contingency plan - A State may choose to establish a number of indicators to trigger contingency measures. For example, one scenario for ozone may be an increase in volatile organic compounds (VOC) emissions which exceeds a predetermined "action line" level (encroaching into the emission margin of safety), but does not necessarily produce ozone violations
. Another situation, regardless of the actual VOC emissions, may involve actual violations of the national ambient air quality standards (NAAQS) for ozone. For CO, the trigger will probably have to be based on ambient concentrations, but a specified emission level may be used as a supplement in some situations
. 2) Structured levels of measures to be implemented due tothe extent of the problem- Once the State has established the indicators and trigger levels, it may identify specific measures to correspond to each of the triggers. For example, if the first scenario involving ozone occurs with no violations, then certain defined measures may be taken, such as: (a) requirement for VOC emission offsets for newand modified major sources at 1 .1 to 1, as required for "marginal" areas under the Clean Air Act; (b) completion of comprehensive VOC emission inventory; and (c) implementation of one or more transportation control measures sufficient to achieve at least 0.5 percent reduction in actual areawide VOC emissions. Where violations do occur, additional defined measures may be implemented, such as Stage II vapor recovery or enhanced inspection/maintenance program . Finally, if the above controls still are not successful in curtailing violations of the ozone NAAQS, additional measures may be employed (e.g., requirement for VOC emission offsets for newand modified major sources at 1.15 to 1, as required for "moderate" areas pursuant to the Act)
. Even more extreme measures may be implemented, such as requiring VOC controls on minor newsources (less than 100 tons) and requiring reasonably available control technology on sources covered by newEnvironmental Protection Agency (EPA) control techniques guidelines documents. As a last resort, if the above measures fail to bring the area back into attainment, the State could commit in its contingency plan that it will request designation to nonattainment at the appropriate classification. This last measure is not essential, as EPA has the authority under section 107 to unilaterally redesignate an area.

### 3) Detailed description of particular measures to be

undertaken - The State should provide as much detail as possible concerning the contingency measures to be implemented. For example, if transportation control measures are included, the plan should specify the levels to which they will apply. For instance, such specifications could include trip reduction programs for employers of more than x_ number of employees that will mandate a specified vehicle occupancy rate; transit improvements such as purchase of y number of buses to be placed on specified routes; traffic flowimprovements (e.g., no left turns at specified blocks) ; alternative fuels programs for fleet vehicle operations over a specified size fleet; vehicle antitampering programs; and other innovative transportation control measures. 

### 4) Discussion of preparatory actions necessary before actual implementation of certain measures - The plan should identify the procedure to be used to adopt and implement the contingency measures to ensure promptness. For instance, before implementation of Stage II vapor recovery, affected individuals/industries need proper notification. Local and State officials should be well informed of any changes. An official notification scheme should be included as part of the contingency plan. In addition, the State should submit a schedule of when each of these elements of the procedure will be completed. The schedule should also account for the time needed by the State to adopt specific measures.