Commissioners approve Diamond Spear SUP amendment to allow seasonal asphalt plant, with DEQ permit requirement

Park County commissioners approved an amended special use permit for Diamond Spear LLC to allow a temporary hot‑mix asphalt batch plant on an existing gravel pit, choosing a seasonal operating window and imposing conditions that require state construction permits and mitigation measures before operation.

Planning staff described the request as an amendment to SUP 256 for a gravel mining operation on a roughly 157‑acre parcel with a designated 15‑acre operating area. The applicant estimates initial material needs tied to a state resurfacing project on Highway 14A of roughly 34,000 tons of mix (staff cited an applicant estimate of about 1,600 truckloads for the work). Because of the nature of asphalt plants, staff determined the change was not minor and required board approval; staff presented three timing options: unlimited, seasonal (Apr. 1–Oct. 31), or a single limited year option.

Dozens of nearby residents testified over two hearing sessions, citing concerns about air quality, dust and particulates, noise, trucking and traffic, groundwater and irrigation impacts near the Garland Canal and Shone River, and property values. Several speakers described family members with respiratory issues and urged strict limits and monitoring. "There is evidence that fine particulate matter from this kind of processing... are common with known impacts on asthma," one resident said when urging caution.

Mountain Construction representatives and the owner’s counsel responded that the gravel resource will be mined and trucked regardless of whether an on‑site asphalt plant is present, and that portable asphalt plants are permitted and regulated by the Wyoming Department of Environmental Quality (DEQ). The company’s general manager, Kim Wilson, told the board that the hot plant type proposed has a current DEQ air‑quality permit template and that DEQ performs stack testing and permit oversight; she referenced a permit (CT1919) on file with DEQ and described baghouse and emissions testing procedures.

Commissioners questioned enforceability of open‑ended mitigation language and asked whether DEQ had authority and technical standards to monitor emissions, dust and noise; staff and agency notes referenced noise decibel standards and DEQ air‑quality oversight. After discussion the board approved the amendment with staff’s recommended conditions and selected option two: allow asphalt operations seasonally between April 1 and October 31 each year, subject to two key preconditions: the applicant must provide evidence of required DEQ construction/air permits before commencing operations, and the operator must mitigate noise, emissions and dust to the greatest extent practicable. The board also retained original SUP conditions.

The approved amendment contains operating windows, required state permits and monitoring obligations; commissioners said the seasonal limit and DEQ oversight were intended to balance property‑owner rights and neighbor protections.

Next steps noted in the hearing: the applicant must secure and submit DEQ construction/air‑quality permits and demonstrate compliance before starting asphalt production at the site.