SUMMARY OF WORK

The Carthage Mine Safeguard Maintenance Project is located between the towns of SanAntonio and Bingham in Socorro County, New Mexico. The project area (see Sheet No. 2) is on private surface ownership in Section 10, 15 and 21, Township 05 South, Range 02 East (USGS 7.5’ Canon Agua Buena and Cerro De La Campana Quadrangle).

This project involves maintenance to existing mine safeguard structures and safeguarding of a subsidence feature. Four features were addressed:

Feature AML C-4 Maintenance: o Shaft with a depth of over 100 feet. Maintenance required removal of the previous AML safeguard structure from 1993. The previous structure consisted of 12’ x 3” robust treated timber planks. No historical mine timber cribbing was impacted during construction. The newly constructed safeguard method included a concrete collar supporting carbon steel grating and a bat gate with removable bars made of TS 2×4 mild steel. The ground was excavated, moisture conditioned and compacted before construction of the concrete collar.

• Feature AML C-6 Maintenance: o Decline adit that was previously safeguarded in 1993 with backfill using mine waste and on-site material, the feature began to experience subsidence. Safeguard method included construction of a polyurethane foam (PUF) Plug Backfill safeguard feature to abate subsidence. A PUF form was constructed with filter textile and chicken wire. Two feet of backfill was mounded over cured PUF, moisture conditioned and compacted.

• Feature AML C-7 Maintenance: o Decline adit that was previously safeguarded in 1993 with a bat gate culvert including a gabion wall. Maintenance included replacement of the Master lock with a new lock to ensure easier access to the swinging gate. Any damage to the gate from accessing old lock was repaired.

• Feature AML R-10 Maintenance: o Decline adit that opened to a height of 8 ft extending back about 25 ft deep and pinched closed to a height of 2 ft. Previously safeguarded in 1997 with backfill, construction of a berm and reclaimed GOB piles. The adit feature had historic timber cribbing. In 2023 the adit demonstrated good aspects for bat habitat. Over time, stormwater caused subsidence the adit became less bat friendly. NM AMLP Constructed a PUF plug and backfilled feature to abate subsidence. A PUF form was constructed with filter textile and chicken wire. Two feet of backfill were mounded over cured PUF, moisture conditioned and compacted. An earthen berm was constructed perpendicular to a dry watercourse to divert stormwater away from AML feature R-10 and prevent future subsidence.

• Seeding and mulching of all areas disturbed by construction.