UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

Office of Air Quality Planning and Standards

Research Triangle Park. North Carolina 27711

1JUN 1982

..

MEMORANDUM

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

Redesignations

FROM: G.T.

Ozone/Carbon

Helms, Chief

Monox.ide

jJ. (.

Programs

\~Branch (1·10·-15)

TO: 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 Schult~ at (919) 541-5511.

Attachment
ATTACHMENT

Example of Ozone Contingency Plan Provisions:

The following provisions might be included in a contingency plan:

1) Inclusion ot 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 to

the 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 new and 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 voe emission offsets for new and modified maj~r 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 new sources (less than 100 tons) and

requiring reasonably available control technology on sources

covered by new Environmental 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.
2

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 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 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.