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On August 27, 2012 Ahtna Engineering Services (AES) mobilized and initiated the remediation process of tunnel YUM070712 (Archibald) in San Luis, Arizona. Equipment was lowered into the exit breach of the tunnel to map out the entire path of the tunnel. The tunnel was located and marked on the surface from the warehouse (508 Suite A) exit breach to the primary fence (International Border). The existing sandy soil condition was a constant problem for all access holes. The primary fence access hole was 60 inch diameter with a corrugated pipe installed to create a bulkhead in the tunnel. The primary fence access hole was filled with 3000 psi, low viscosity concrete, and backfilled with native material. There were nine (9) 24 inch diameter access holes drilled along the length of the tunnel. The access holes collapsed except holes number 3, 4, and 5. The remaining access holes were sleeved with 18 inch diameter HDPE pipe to maintain their stability and prevent the possibility of collapse. The tunnel was filled with low viscosity concrete up to 4 feet below the surface between the primary fence and the warehouse. Reinforcing steel was installed in the existing exit breach in the warehouse as required by the structural engineer. 3000psi concrete was pumped and vibrated into the existing exit breach in the warehouse. The exit breach was completed with a smooth finish. The access holes shafts between the primary fence and warehouse were filled with native soil and compacted. The parking lot and park were graded and restored to their natural state and serviceable condition. The job site was swept and cleaned of all excess spoils, debris, trash, and were disposed of at the designated area provided by CBP. The project was completed and accepted by the CBP representative on September 6, 2012.

Categories: Environmental