The Permian Delaware Basin in New Mexico is host to extensive potash deposits. The Delaware Basin deposits were the principal source of U.S. potash beginning in 1931. These deposits continue to be mined today. When New Mexico potash production was near its peak in 1966 and before the giant potash deposits of Canada were discovered, the Delaware Basin was the source of about 25 percent of the world’s potash (Jones and Madsen, 1968). In 2006, the Delaware Basin deposits supplied 19 percent of the potash for domestic use (Barker and others, 2008).

The Delaware Basin formed in what today is west Texas and southeast New Mexico. The basin is bordered on the east by the Central basin platform and on the west by the Guadalupe Mountains. Midland Basin, east of the Central basin platform, is not known for potash deposits. The Delaware and Apache Mountains border the basin on the southwest and south, respectively. The basin has a 9,144-m-thick accumulation of Cambrian to Quaternary sedimentary rocks. Potash formed in the 609-m-thick Salado Formation that is part of the Ochoa Series (Lowenstein, 1988). The Ochoa Series is a sequence of ocean-basin carbonate reef, shoal, shale, and turbidite sandstone deposits. The series formed when a Permian seaway advanced into the area of what is today southern Arizona and New Mexico; northern Sonora, Mexico; and west-central Texas (Hayes, 1964).

Salt evaporites that contain potash form stratiform beds that overlie the basin, reef, and shoal marine-carbonate deposits. The McNutt zone of the Salado Formation contains multiple potash beds that are interbedded primarily with halite and polyhalite but also contains minor siltstone and anhydrite (Lowenstein, 1988).

The project is proposed to consist of six injection wells, five extraction wells, and three monitoring/extraction wells to facilitate the injection and extraction of process brines to and from the former workings. The design of these wells includes triple casing/cementing and the use of specific construction materials to function in a saline environment.

Six injection wells would be located to allow the injection of conditioned brine up to the maximum flood level of the former potash mine workings. Conditioned injectate would be composed of Rustler groundwater and NaCl. A flow rate of up to a maximum 2,000 gpm would be divided between the six injection wells and sequenced to facilitate strategic filling of the mine units.

Over time, the leach lakes would dissolve potash remaining in the former workings. The pregnant brine would then be recovered through the five extraction wells positioned at the lower portions of the former workings. Extraction wells would also be used to monitor fill elevations for flood control and to collect brine for quality monitoring. Each well will be equipped with instrumentation to allow flow rates and pressures to be monitored, and the static brine level (elevation of the flood pool) to be monitored, recorded, and connected to an automated alarm/shutdown system. This monitoring and control system will provide automated safeguards to maintain the flood pool elevations at or below the maximum levels

The project is designed to recover and process potassium chloride ore from pillars and limited adjacent areas of the back, floor and ribs from former underground workings which are no longer economically recoverable via conventional mining techniques. The area proposed for potash extraction occurs within existing Intrepid leases. Limited surface disturbance would occur in the form of surface pipelines, well pads, utility conveyances, solar evaporation ponds, and a new processing mill. Surface disturbance would primarily occur on Intrepid owned land but also on BLM, State of New Mexico, and other deeded surface.

Components of the Proposed Action:
•Extraction and conditioning of groundwater from four Rustler Formation wells to form an injectate solution. Components of the Proposed Action
• Injection of the injectate solution via six injection wells and a surface piping system into the lower portion of four separate former underground mine workings areas ........