Simulations using the Argonne National Laboratory cumulative air modeling assessment indicated potential for future ozone concentrations from development of disposed lands to temporarily exceed the 0.084 ppb standard for select areas of Las Vegas Valley. The temporary exceedances were considered a “worst-case” scenario because the model was constructed using very conservative approaches and only included reformulated fuels as a VOC reduction strategy.

The Argonne National Laboratory air-quality model also assumed a disposal rate of approximately 4,000 acres per year based upon the rate of sales at the time and the assumption that the market could support this rate of disposal into the foreseeable future. In the past 2-3 years, deteriorating economic conditions have reduced demand for additional housing and land; the number of acres actually disposed has dropped considerably in the Las Vegas Valley from a high of 10, 000 acres [2003-2006] to a low of 100 acres [2007-2010]. The current downward trend in land sales is expected to continue for the next several years based on the present economic conditions.

The results projected in the ozone model still adequately address future expected levels of ozone in the Las Vegas Valley. Future ozone concentrations resulting from development of disposed lands probably will be less than predicted by the model because of the greatly reduced rate of land disposal, conservative modeling approaches and likely implementation of VOC reduction measures not considered in modeling scenarios. The current 0.075 ppb ozone standard is not likely to be exceeded based upon this rationale, but there is some uncertainty involved with modeling results. In order to address uncertainty, the following measures will be implemented. BLM will coordinate CCDAQEM to ensure federal actions are consistent with the future guidelines provided by CCDAQEM. BLM, in coordination with CCDAQEM, also will determine if additional modeling is needed in the future if disposal rates increase to initially assumed values and specific VOC reduction measures are identified and implemented under a revised SIP.

A dust control permit will be required for this proposed action. Ensure compliance with dust regulations for the duration of the proposed action.