020-17 Wyo. Code R. § 17-43
When site specific geological data/information are not available to calculate acceptable soil cleanup concentrations, default remediation standards shall be based on a child's exposure using both oral ingestion and inhalation pathways, and the potential for soil contamination to migrate to groundwater. The default soil condition for organic compounds has been established as a sandy clay formation with a minimal organic carbon content of 0.1% and a depth to the first groundwater table from the bottom of the default contaminated soil zone equal to one foot. The default thickness of contaminated soil is five (5) feet. The annual precipitation rate is fourteen (14) inches per year with a 50% infiltration rate. These conservative default soil conditions indicate residential exposures with protection of groundwater quality to EPA/WDEQ drinking water or equivalent drinking water levels.
020-17 Wyo. Code R. § 17-43