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Pacific Southwest, Region 9

Serving: Arizona, California, Hawaii, Nevada, Pacific Islands, Tribal Nations

Reasonably Available Control Measures (RACM) for Vacant Lots and Open Areas

NOTE: This content is no longer being updated. The most up to date information can be found in Federal Register Notices and Approved Air Quality Implementation Plans in Region 9.

Motor Vehicle Disturbances (i.e. trespassing)

What is considered motor vehicle trespassing?

Trespassing is unlawful and occurs when motor vehicles, including cars, trucks and off-road vehicles, drive across a vacant lot. Typically, trespassing occurs when drivers see opportunities to take "short-cuts"across property to access a public road or destination. Tire tracks are evidence of trespassing. Trespassing includes vehicles parking on a lot not intended for public access. Trespassing does not include the owner's use. However, if the owner disturbs ½ acre or more on a vacant lot, the surface is subject to RACM under the "Disturbed Surfaces" provisions.

What is required?

The owner/operator is required to either:

1) prevent motor vehicle trespass from occurring; or

2) stabilize the trespassed surface with washed gravel or a chemical/organic stabilizer.

If gravel or stabilizer is applied and trespass continues to occur, the gravel/stabilizer may need to be maintained over time so that the surface is stabilized according to the FIP rule vacant lot test methods.

Some examples of how to prevent trespass include:

putting up 3 foot tall fencing (metallic, wood, plastic, etc.);

using posts and cable (posts should be greater than or equal to 2 inches in diameter and cable should be greater than or equal to 1 ½ inches thick and hang no lower than 1 foot;

planting shrubs or trees;

using cement blocks/barriers or boulders 1 ½ feet in diameter, spaced no greater than 5 feet apart;

constructing a rock or cement wall 1 ½ feet tall;

roping off a part(s) of the lot.

"No trespass" signs may be used. However, if they are not observed by trespassers, then trespass will not be prevented as required.

Are barriers required around the whole lot?

In many cases, barriers around the whole lot will not be necessary. Barriers should be placed wherever corners are being cut, or along access points to trespassed parts of the lot. The preventative measure selected should be tailored to meet the specific trespassing circumstances.

When are RACM required?

RACM are required 60 calendar days following the initial determination of disturbance.

Disturbed Surfaces

Under what conditions do RACM apply?

RACM apply whenever there is ½ acre or more of disturbed, unstabilized surface area on a vacant lot or urban or suburban open area that remains vacant for more than 15 days. The disturbed surface area does not need to be continuous for requirements to be triggered. Once the disturbed areas on the lot have been tested for stability, if the total size of unstable surface adds up to at least ½ acre, the unstable areas need to be controlled.

What is required?

The owner/operator is required to stabilize the surface. Once the surface is stabilized, it is important that further disturbances be prevented, or alternatively, that the owner/operator take steps to stabilize the surface within 60 days following any future disturbances.

Some options on how to stabilize the surface include:

watering to form a crust;

planting vegetation;

applying chemical/organic stabilizer;

applying gravel; or,

restoring the lot to its natural (undisturbed) state.

Whatever the RACM chosen, the surface needs to be stabilized in accordance with the FIP rule's vacant lot test methods. Before applying RACM, the owner/operator should consider whether the chosen control will effectively stabilize the surface and the quantity needed. For example, watering may not work on all types of soil and its success is subject to the amount of water used.

What are the requirements for weed abatement?

If a lot is weed abated by disking, blading, plowing under or any other means that disturbs the soil, all of the following RACM are required:

Apply water or chemical/organic stabilizer immediately prior to weed abatement;

Prevent or eliminate dirt track-out onto paved surfaces and access points adjoining paved surfaces;

Stabilize the surface immediately following weed abatement using water, chemical/organic stabilizer, gravel, compaction or an alternative control measure.

If a lot is weed abated by mowing or cutting so that at least 3 inches of weed stubble remains, no RACM are required. Also, if the weed abatement is covered under an approved permit by Maricopa County Environmental Services Division, the FIP rule requirements do not apply. If an owner/operator anticipates that the surface will need to be weed abated on a regular basis, it is best to take preventative measures, such as using a weed abatement technique that does not disturb the soil in order to maintain compliance with the FIP rule in the future.

When are RACM required?

RACM are required 60 calendar days following the disturbance. Weed abatement requirements apply at the time the lot is being disturbed.

If a disturbed vacant lot has naturally re-stabilized, are RACM still required?

No. In some cases, significant rainfall will cause a crust to form and re-stabilize a disturbed surface. RACM are not required to stabilize an already stable surface, but are required if the surface is re-disturbed and rendered unstabilized again.

For more information:

Please contact Colleen McKaughan, Associate Director, air Division, U.S. EPA Region 9 at (520) 498-0118. Send questions and comments to r9.phoenixdust@epa.gov.


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