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Rio Grande Resources Corporation

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1.0 Site Identification

Type of Site: Uranium Recovery Facility
Location: Hobson, TX
License No.: R02402
Docket No.:
License Status:  

2.0 Site Status Summary

A radioactive material license was issued to Chevron Resources Company in September of 1977 authorizing radioactive materials for a Troxler Model 3411 moisture/density gauge.  The license was subsequently amended in October of 1977 to authorize processing of uranium ore into uranium concentrate.  From that license the Panna Maria mill site was developed and operated.  The mill site consisted of a milling complex, with a dryer, and a tailings impoundment of approximately 160 acres adjacent to the mill complex to dispose of tailings and other waste from the milling process.  The mill processed ore from conventional surface mines in Texas and ore from the Chevron Mt. Taylor mine in New Mexico.  Ore from mines in Texas were transported by truck to the mill, while ore from the Mt. Taylor mine was shipped by rail to a spur near the Panna Maria mill facility.  Ore was off loaded from the rail cars to trucks and transported the remaining distance to the mill site for processing.

In addition to the by-product material and other waste from the Panna Maria Mill Site operations, the licensee was also authorized to receive processed materials containing uranium for the purpose of reprocessing for its uranium content.  Additionally, the licensee was authorized to receive uranium processing waste from other uranium operations for disposal in the mill tailings pond.

Authorization for processing was removed from the license in July of 1993 and replaced with an authorization for possession incidental to decommissioning and reclamation activities.

Chevron sold the facility to Rio Grande Resources Corporation (RGR), a subsidiary of General Atomics.  The license was amended in May of 1997 to reflect the transfer of the facility to RGR.  

Rio Grande Resources Corporation completed decommissioning of the mill site.

The tailings impoundment has been capped and a vegetative cover established.

The tailings impoundment is still being monitored for performance.

Since all structures and equipment have been removed from the site, there will be no release of equipment and materials to unrestricted use.  The criteria for release of the site/termination of the license includes demonstration that the tailings impoundment does not exceed the radon flux limit of 20 pCi/m2-sec; gamma levels are indistinguishable from background; radium-226 concentration in soil does not exceed 5 and 15 pCi/g of radium-226 in the first 15 centimeters, and subsequent 15 centimeter soil horizons, respectively; demonstration that the radium benchmark dose is not exceeded; demonstration that the tailings impoundment and disposal cell have stabilized; and either demonstration that the groundwater does not exceed the limits specified in a table that is comparable to Paragraph 5C in 10 CFR 40, Appendix A, or does not exceed alternate concentration limits, if so established.

3.0 Major Technical or Regulatory Issues

Groundwater remains an outstanding issue.  The licensee has submitted an application for alternate concentration limits.  The licensee continues a groundwater sampling program and is in the process of reestablishing background groundwater concentration levels for groundwater compliance.

The licensee has obtained a separate license to operate an in situ leach uranium recovery processing facility on a parcel of land adjacent to the tailings impoundment.  The licensing and operation of such a facility should in no way interfere with final closure of the tailings impoundment.  Thus, termination of R02402 for the tailings impoundment can proceed independently of any other site activity.

Page Last Reviewed/Updated Thursday, August 23, 2018