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Ahtna is mapping out the path of the tunnel at the steel yard. On March 26, 2012, our team mobilized and initiated the remediation process of tunnel OTM112911 (Calle de Linea) in Otay Mesa, California. A 24-inch diameter access hole was drilled to allow equipment into the tunnel to map out the entire path of the tunnel. The tunnel was located and marked on the surface from the warehouse (6754 Calle de Linea) exit breach to the primary fence (International Border). Three access holes were drilled in the loading area behind the warehouse. The existing concrete was saw cut in a 4 foot x 4 foot dimensions to allow for adequate drilling. There were 16 24-inch diameter access holes drilled along the length of the tunnel. The backhoe with a hydraulic hammer was used to break up the concrete in the access holes in the loading area. All drilled access holes were successful into the tunnel. An 8 foot x 10 foot steel plate was installed in the tunnel at the primary fence location as a bulkhead. The tunnel will be filled with low viscosity and 3000psi concrete. The steel plate was incased with 3000 psi concrete. A 30 foot x 24 inch corrugated pipe with a smooth interior was installed inside the tunnel in the field area between the primary and secondary fences. A 30-foot x10 inch PVC pipe was installed vertically into the 24-inch pipe to allow access into the corrugated pipe. 3000 psi concrete was pumped, poured, and vibrated into all access holes up to 4 feet below the surface between the secondary and the primary fences. The 3000psi concrete was poured under the main truck road in the tunnel. The remainder of the tunnel was filled with low viscosity concrete up to 6 feet below the surface between the secondary fence and the warehouse loading area. The remainder of all the access holes was filled with 3000 psi concrete. Reinforcing steel was installed in all access holes in the loading area and in the existing exit breach in the warehouse as required by the structural engineer. 3000 psi concrete was pumped and vibrated into the existing exit breach in the warehouse. The exit breach was completed with a smooth finish. All three access holes in the loading area were completed with a broom finish and dated. The remainder of the access holes shafts between the primary and secondary fences as well as the access holes in the steel yard was filled with native soil and compacted. The field was graded and restored to its natural state. The service road was restored to a serviceable condition. The job site was swept and cleaned of all excess spoils, debris, and trash that were disposed of at the designated area provided by CBP. The project was completed and accepted by the CBP representative on April 6, 2012.
Categories: Construction