Imperial County

Imperial County Air Pollution Control District (IAPCD)

California’s ambient air quality standards classified Imperial County as nonattainment for ozone and PM10. Based on EPA standards, the county was designated moderate nonattainment for the 2008 8-hour ozone standard and PM2.5. Some parts of the county were also designated as serious nonattainment for PM10.

ERCs are available for six different pollutants:

Pollutant Significant Emission Rates
NOx and ROG >137 lbs/day
PM10 and SOx >150 lbs/day
PM2.5 and CO >550 lbs/day

To satisfy offset requirements, new or modified major facilities in nonattainment areas must obtain ERCs to satisfy the offset ratio requirements for proposed emission increases.  The offset ratios for nonattainment area for ozone is shown in the table below.

Location Offset Ratio
Within the same source 1 to 1
Within 50 miles of the source >1.2 to 1
More than 50 miles from the Source, and within air basin No greater than 3 to 1 or less than 1.2 to 1

That means if 100 tpy of VOCs are emitted from a proposed new or modified major facility located in a nonattainment for ozone, the facility could offset emission increases if it would obtain 100 tpy of ERCs if within the same source; 120 tpy of ERCs if within 50 miles of the source; or no greater than 300 tpy and not less than 120 tpy of ERCs if source is more than 50 miles away.