1.1.1 Incident Category

Mine Category Assessment Protocol (MCAP) reconnaissance in support of the Tronox settlement

1.1.2 Site Description

120 mine claim areas, 26 mine claims are specifically identified in the Tronox settlement, with an additional 6 mine claims determined as 'other mines' within the Tronox settlement

The MCAP Target Sites, historical site screening information, and other relevant layers supporting the MCAP site visits are displayed on the Region 9 Navajo Operational Viewer located at: https://r9.ercloud.org/navajoops/.

1.1.2.1 Location

Red Valley, AZ 86544 - The MCAP effort will take place throughout the Northern agency of the Navajo Nation, extending from the Lukachukai Mountains north to Teec Nos Pos

1.1.2.2 Description of Threat

Potential releases and the threat of future releases of hazardous substances, namely: uranium and its progeny (i.e., radium-226 and radon) and ionizing gamma and alpha radiation associated with those progeny.  The likelihood of direct human exposure, via ingestion and/or inhalation of hazardous substances, and the threat of future releases and migration of those substances, pose an imminent and substantial endangerment to the public health or welfare or the environment based on the factors set forth in the NCP, 40 CFR § 300.415(b)(2). 

2.1.1 Narrative

On Tuesday, April 19^th, two MCAP field teams successfully visited portions of 12 AUM sites and 10 Non-AUM Areas of Concern found throughout the areas of Mesa V, Mesa IV, and the access road leading the mesas.  The field teams found the upper extents of the AUMs were generally reclaimed, although scattered waste rock was still present at many of the sites.  It was also determined that further reconnaissance would be necessary to better evaluate the potential waste accumulation areas found within the lower extents of many of the mines.  Many of the non-AUM target areas (as identified during the ASPECT flyover gamma scanning) were found to largely consist of areas that did not appear to be impacted by any mining operations, with relatively low levels of gamma radiation, however some isolated areas of elevated gamma readings were found at those non-AUM target areas along the upper plateau of Mesa V, and along apparent former haul roads alongside the primary access road, north of Mesa V.

2.1.2 Assessment activities to Date

On April 19, 20 of the 96 planned sites were evaluated. Two of the sites were only partially evaluated because a portion of the site was below a cliff. A strike team on ATVs will be deployed to further evaluate these incomplete sites at a later date.

2.1.3 Progress Metrics

20 of the 96 site have been evaluated to date, this represents 21% completion.

A list of all of the sites and their MCAP status can be found at:
https://www.epaosc.org/sites/11282/files/MCAP%20Target%20Sites%20041916.xlsx                    

On Wednesday, April 20th, the MCAP field team plans to locate access routes to reach the lower ranges of Mesa V, and delineate the extent of mine waste that has been pushed off the Mesa areas, as well as continue conducting site visits throughout the Mesa VI and Mesa IV areas.

1 OSC

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