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(Page 2) MINE fD # OR PROSPECTING ID #: ~~-~nnn_nsn INSPECTION DATE: n~/ni/ns INSPECTOR=S INITIALS: ~ iw OBSERVATIONS This inspection was conducted as the result of a citizen's complaint from Toby Espinosa by and through his attorney, Frank Ruybilad. The inspection was performed by Tony Waldron and Harry Posey from DMG along with Phil Dorenkamp of Las Animas County. The landowner, Andy Castillo, was also present during the inspection. The site is located approximately 12 miles west of Trinidad, Colorado and sits on an alluvial or colluvial terrace on the south side of the Purgatoire River. The county recently converted an existing 1 l Oc.oper~tion to a 1 12c by adding 8.84 acres to the existing 9.90 acres for a new total permitted area of 18.74 acres. The new area was down-slope from the existing disturbed area that presently occupies an upland position along a small ridgeline. The focus of the complaint is the presence of an old and poorly marked cemetery near the northwest corner of the permit area. The complaint continues to allege that mining related activities are occurring too close to the cemetery. The cemetery is situated on a relatively levetpart of the terrace, approximately 100 feet before the terrace out-slope drops off into the Purgatoire River valley. A gravel layer that is the target of mining underlies the terrace. During permitting of this site the landowner and the operator entered into an agreement (per Rule 6.4.19) to protect the cemetery by maintaining a setback of 10 feet on the south and west side boundaries, and mining no closer than the existing fence line on the north and east sides. The operator further delineated the boundaries of the cemetery by means of tee-posts and a single strand of barbed wire to prevent any confusion about where the cemetery boundary was located. The closest disturbance allowed i510 feet from the perimeter of the fenced area. In addition, based on a previous complaint concerning this site, the county agreed to expand the perimeter of the cemetery by an additional 5 feet in this area and continue to maintain the 10-foot set-back from this newly delineated boundary as well as expand the boundary in the area where the "unmarked graves" are reportedly located. This was verbally agreed to on the site, furthermore, the county indicated that they would mine through the overburden at 3H:1 V until they exposed the gravel deposit at which time they would mine the deposit vertically followed by backfilling at 3H:1 V. As the overburden appeared to be 4-6 feet thick in this area, this would have moved the actual gravel mining another 12 to 18 feet away from the perimeter of the cemetery for a total distance of approximately 30 feet away from the perimeter fence before any actual gravel extraction took place. However, based on this inspection, a new and more clearly defined set-back is being required. A general (and conservative) rule of thumb is that protected structures should be at least twice the distance away horizontally as the depth of the excavation. In other words, if the pit were to be excavated 20 feet deep the horizontal distance from the toe of the slope to the protected structure would be 40 feet to prevent slope failure from extending into the protected structure. Although this is only a "rule of thumb", it is conservative and it was suggested that the operator observe it until a full stability analysis could be conducted. The analysis is likely to demonstrate that mining could occur safely at a distance closer to a protected structure. This conclusion is based on past experience with numerous mining sites in varying types of geologic conditions. Also, even though the last inspection report indicated that DMG collected samples and would conduct a stability analysis, it has since been determined that the operator must conduct the analysis if they want to mine closer than 2H:1 V from a protected structure with DMG review and approval. In order to clarify this issue, the proposed set-back will be cited as a problem on page 4 of this report along with corrective actions which will be to submit a technical revision to the permit application clearly identifying the proposed set-backs and slope mining restrictions or providing a stability analysis demonstrating that steeper mining could occur while maintaining protection of the identified structures. With respect to the specific concerns raised in the letter that stimulated this inspection, the operator has not expanded the disturbance beyond what existed during the last inspection on the south side of the cemetery. They did excavate additional material along the east side as well as stripping additional topsoil along the west