If your fleet average in-use emission rate is greater than your target rate for a given compliance year then you must apply best available control technology (BACT) to a percentage of your fleet. The percentages differ by fleet size and year.
The first thing you need to do is get the percentages. You can find these by clicking on the one following boxes in the compliance chart:
BACT is defined as:
Installing a Verified Diesel Emission Control Strategy (VDECS) on the vehicle's engine, or retiring a vehicle, designating a vehicle as a permanent low-use vehicle, repowering a vehicle with a higher tier engine, or rebuilding the engine to a more stringent emissions configuration.
A VDECS must be verified by ARB as a Level 2 VDECS (reduces PM by 50%-84%) or Level 3 VDECS (85%+ reduction in PM). The highest efficiency VDECS available for each engine and application must be used.
You can also meet BACT using a variety of different types of credits. As indicated by the compliance chart, once you have determined your percentage BACT obligation for a given year the next step is to see if you have credits you could use to meet your BACT obligation for a given year.
If you are assessing the use of VDECS the following ARB website lists verified devices.
For engine specific availability see: