Any regulated portable equipment brought to an active jobsite within the Yolo-Solano AQMD must have either a valid District Permit to Operate (PTO) or a valid statewide Portable Equipment Registration Program (PERP) placard and sticker issued by the California Air Resources Board (ARB).
Regulated portable equipment under these rules includes:
- Non-road Internal Combustion (IC) engines rated over 50 horsepower
- Abrasive blasting operations (confined or unconfined)
- Concrete batch plants
- Sand and gravel operations (screening, crushing, or recycling)
- Tub grinders or trommel screens
Local Permit vs. Statewide Registration
PERP was created in 1997 to address concerns from the business community and local air districts. Most districts required local permits for portable equipment, but enforcing permit rules on transient operators proved difficult and expensive. Meanwhile, businesses who complied with these regulations found obtaining permits in multiple air districts – many of which had different rules – cumbersome and expensive. Statewide registration was developed as a ‘method to streamline and simplify the permitting of portable equipment’. The statewide program is ‘voluntary’, however the underlying requirement in most districts throughout the state (including Yolo-Solano) is not voluntary. So, equipment owners can comply with the underlying permit requirement in each district they operate, or if their equipment qualifies, they can obtain a single registration in the voluntary statewide program.
Under state rules, equipment registered under PERP and operating in compliance with the requirements of the program is not subject to a similar local operating permit requirement.
Sample PERP placard
Businesses found operating regulated equipment within Yolo-Solano AQMD without either a valid PERP or a District Permit to Operate will be cited for enforcement action.
Regulated Engines
Non-Road IC Engines
Non-road engines are often called portable engines. These are engines which do a work function separate from providing propulsion. They are often towed behind a vehicle, and include generators, compressors, concrete pumps and tree chippers. They are sometimes mounted as an auxiliary engine on a vehicle, such as a compressor or generator mounted on the bed of a truck. These engines are subject to the portable diesel engine Airborne Toxic Control Measure (ATCM).
As stated above, in order to operate in our district (and most other districts throughout the state), non-road engines (including those which are part of a two-engine vehicle – see below) must be permitted with our District or have a valid PERP. If you are registered in the PERP program, you must display the green metal PERP placard on the outside of the equipment and keep a copy of the certificate and conditions with the unit. The District enforces these requirements.
Engines rated less than Tier 4 cannot be registered in PERP, but in some cases may be eligible for a short-term District permit. Contact the District at 530-757-3650 for more information.
Off-Road Vehicles
Off-road vehicles such as tractors, graders and tracked vehicles are subject to a separate state regulation and, unless exempt, must be registered through ARB’s Diesel Off-Road Online Reporting System (DOORS). Once registered, the vehicle should have a red sticker with white letters showing the Engine Identification Number (EIN). Vehicles used exclusively for agricultural purposes are among those exempt from this regulation under state rules.
Sample DOORS sticker showing EIN
The District does not enforce this regulation locally – it is enforced by the ARB. More information can be found at ARB’s website.
On-Road Vehicles
On-road vehicles such as trucks, buses and privately owned street sweepers are subject to the ARB’s on-road regulation and must be registered in the Truck Regulation Upload, Compliance and Reporting System (TRUCRS).
The District does not enforce this regulation locally – it is enforced by the ARB. More information can be found at ARB’s website.
Two-engine Vehicles
Non-road engines may be an integral part of a two-engine vehicle, such as a street sweeper, vacuum truck, drilling rig, or crane. For most two-engine vehicles, both engines are subject to the off-road diesel engine ATCM, which dictates when the engines need to be upgraded. Two-engine vehicles need to be registered in two programs in order to operate in Yolo-Solano AQMD:
- Two-engine off-road vehicles need to be registered in DOORS and if the auxiliary engine is over 50 hp, it needs to be registered in PERP.
- Privately owned street sweepers need to be registered in TRUCRS and if the auxiliary engine is over 50 hp, it needs to be registered in PERP.
Publicly owned Vehicles
Publicly owned vehicles (including two-engine street sweepers) are subject to the Fleet Rule for Public Agencies and Utilities. Non-road and auxiliary engines that are over 50 hp need to be registered with PERP.
How to Register in PERP
Visit the ARB’s PERP webpage to register a portable engine.
