MARIPOSA COUNTY AIR POLLUTION CONTROL DISTRICT
RULE 411 - EMISSION OFFSET ELIGIBILITY
- Except in the case of seasonal sources, emission offset quantities shall be calculated on annual, and daily
bases. Per seasonal sources, emission offset quantities shall be calculated on the basis of the season date span
of operation, and daily emission rate, either estimated for proposed sources or averaged over the two year period
preceding the date of application, or other appropriate periods as determined by the Air Pollution Control Officer,
for existing sources.
- Emission offsets may be developed by the reduction of emissions from existing stationary, and non-stationary
sources. Offsets from stationary sources not exempt from the provisions of Rule 501 shall be certified by the Air
Pollution Control Officer through conditions attached to the Permits to Operate of the emission-reducing sources.
Offsets from non-stationary sources, and exempt stationary sources shall be certified by the Air Pollution Control
Officer through new facility Permit to Operate conditions, contracts, or other means deemed adequate by the Air
Pollution Control Officer. Such emission offsets shall take effect no later than 120 days after initial operation
of the new facility or modification.
- The ratio of emissions offsets to the emission from a new facility or modification shall be:
- 1.0:1 for offsets within the facility;
- 1.2:1 for offsets upwind in the same or adjoining Air Pollution Control District, or within a 15 mile radius
of the proposed new facility or modification.
- Sufficient to demonstrate an air quality benefit through modeling in the area affected by emissions from the
new facility or modification for offsets located in areas other than those of 1. or 2. above.
- If an applicant certifies that the proposed new facility or modification is a replacement for a facility or
source which was shut down or curtailed after January 1, 1981, emission reductions associated with such shutdown
or curtailment may be used as offsets for the proposed facility or modification. Sources which were shut down or
curtailed prior to January 1, 1981, may be used to offset emissions increases for replacements for such sources,
- The shutdown or curtailment was made in good faith pursuant to an established plan approved by the Air Pollution
Control Officer for replacement and emission control, and in compliance with air pollution laws, rules and regulations
at the time; and
- The applicant demonstrates to the satisfaction of the Air Pollution Control Officer that there was good cause
for delay in construction of the replacement sources.
- Notwithstanding any other provisions of this rule, any emissions reductions not otherwise authorized by this
Rule may be used as offsets or emission increases from the proposed facility or modification provided the applicant
demonstrates to the satisfaction of the Air Pollution Control Officer that such reductions will result in a net
air quality benefit in the area affected by emissions from the new facility or modification.
- Emissions reductions resulting from measures required by adopted federal, state, or District laws, rules or
regulations shall not be allowed as emissions offsets unless a complete application incorporating such offsets
was filed with the District prior to the date of adoption of the laws, rule or regulations.
- Emissions reductions of one precursor may be used to offset emissions increases of another precursor of the
same secondary pollutant provided the applicant demonstrates to the satisfaction of the Air Pollution Control Officer
that the net emission increase of the latter precursor will not cause d new violation, or contribute to an existing
violation, of any national ambient air quality standard. The ratio of emission reductions between precursor pollutants
of the same secondary pollutant shall be determined by the Air Pollution Control Officer based upon existing air