High level of structural and waterproofng stability leads to long-term service life in underground infrastructures.Interaction between aggressive groundwater with tunnel causes corrosion and damage in concrete structure due to steel reinforcement corrosion and concrete cracks.This study introduces a double waterproofng shield system(DWS)as an innovative solution to waterproofng and structural failures in underground concrete structures.In this method,ordinary shotcrete mixture replaces by an organic polymer concrete(OPC)to construct a water-resistant temporary support right after each partial excavation.Two groups of specimens including reference concrete and OPC specimens were provided and tested in accordance with ASTM C 642.Waterproofng parameters including porosity,pore volume,permeability and hydraulic conductivity have been determined.Results show a remarkable reduction in mentioned parameters for OPC compared with ordinary concrete.Improvement in waterproofng performance of temporary support corresponds to a healthy fnal lining and increase in service life of the structure. High level of structural and waterproofng stability leads to long-term service life in underground infrastructures. Interaction between aggressive groundwater with tunnel causes corrosion and damage in concrete structure due to steel reinforcement corrosion and concrete cracks. This study introduces a double waterproofng shield system (DWS ) as an innovative solution to waterproofng and structural failures in underground concrete structures. In this method, ordinary shotcrete mixture replaces by an organic polymer concrete (OPC) to construct a water-resistant temporary support right after each partial excavation. Two groups of test reference concrete and OPC specimens were provided and tested in accordance with ASTM C 642. Waterproofng parameters including porosity, pore volume, permeability and hydraulic conductivity have been determined. Results show a remarkable reduction in mentioned parameters for OPC compared with ordinary concrete. Improvement in waterproofng performance of temp orary support corresponds to a healthy fnal lining and increase in service life of the structure.