A dispersion and receptor model analysis of a western community's PM-10 problem.

Abstract

Telluride is a resort community located in southwest Colorado at an altitude of 8800 feet above sea-level. The town is situated in the San Miguel Valley near the end of a box canyon surrounded on three sides by mountains. Telluride's permanent population of 1200 can increase to an overnight population of over 4000 during peak ski periods. With the promulgation of a new PM-10 standard in July 1987, Telluride was categorized as a nonattainment Group I PM-10 area. The technical analysis performed to meet the PM-10 Group I State Implementation Plan (SIP) requirements has been described in detail. A brief summary of that analysis which looked at the wintertime problem is presented. The vertical particulate profiles taken in west Telluride consistently showed a well-mixed layer up to 14 m, which corresponds approximately to the maximum plume height of woodsmoke emissions. Above this height, concentrations decreased and reached background levels of about 35 m. Temperature profiles taken concurrently with the particulate data showed temperature inversions had little impact on the mixing depth during stable, drainage conditions. The findings of the DRI study were incorporated into the dispersion modeling in the form of mixing heights and by modifying the vertical profile ofmore » particulates in a box. The uniform distribution initially assumed by the model was modified to that which was observed.« less