UNITED STATESENVIRONMENTALPROTECTIONAGENCY OfficeofAirQualityPlanningandStandards ResearchTrianglePark.NorthCarolina27711 

# 1JUN1982

.. MEMORANDUM
SUBJECT: Contingency Measures for Ozone and Carbon Monoxide (CO) Redesignations
FROM: G.T. Helms, Chief

## jJ.(.**\~** Ozone/Carbon Monox.ide Programs Branch (1·10·-15)
TO: Air Branch Chief, Regions I-X

Several Regions have asked for specific examples ofwhat 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**Schult~** at (919) 541-5511.
AttachmentATTACHMENT Example ofOzone Contingency Plan Provisions:
The following provisions might be included in a contingency plan:

1) Inclusionot several potential scenarios that could trigger implementation of the contingency plan

- AState may choose to establish a number of indicators to trigger contingency measures. For example, one scenario for ozonemay 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 ofthe actual VOC emissions, may involve actual violations ofthe 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 ofmeasures to be implemented due to the extent of the problem

- Once the State has established the indicators and trigger levels, itmay identify specific measures to correspond to each ofthe triggers. For example,'ifthe first scenario involving ozone occurs with no violations, then certain definedmeasures maybe taken, such as: (a) requirement for VOC emission offsets for new andmodifiedmajor sources at 1.1 to 1, as required for "marginal" areas under the CleanAirAct; (b) completion of comprehensiveVOC emission inventory; and (c) implementation of one ormore transportation control measures sufficient to achieve at least 0.5 percent reduction in actual areawide VOC emissions. Where violations do occur, additional definedmeasures may be implemented, such as stage II vapor recovery or enhanced inspection/maintenance program. Finally, ifthe above controls still are not successful in curtailing violations ofthe ozone NAAQS, additional measures maybe employed (e.g., requirement for

### voeemission offsets for new andmodified**maj~r** sources at 1.15 to 1, as required for "moderate" areas pursuant to the Act). Evenmore extrememeasures may be implemented, such as requiring VOC controls onminor new sources (less than 100 tons) and requiring reasonably available control technology on sources covered by new Environmental ProtectionAgency (EPA) control techniques guidelines documents. As a last resort, ifthe 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 lastmeasure is not essential, as EPAhas the authority under section 107 to unilaterally redesignate an area.2 3) Detailed description ofparticularmeasures to be undertaken

- The state shouldprovide as much detail as possible concerning the contingency measures to be implemented. For example, iftransportation 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 ofmore than x number ofemployees that will mandate a specified vehicle occupancy rate; transit improvements such as purchase ofy number ofbuses to be placed on specified routes; traffic flow improvements (e.g., no left turns a.t specified blocks); alternative fuels programs for fleet vehicle operations over a specified siz.e fleet; vehicle antitampering programs; and other innovative transportation control measures. 4) Discussion ofpreparatory actions necessary before actual implementation of certainmeasures
- 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 ofthe contingency plan. In addition, the state should submit a schedule ofwhen 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.