MWD, Preliminary Design of Pre-stressed Concrete Cylinder Pipe (PCCP) Rehabilitation Project – Allen-McColloch Pipeline

UltraSystems Environmental, Inc. (UltraSystems) completed an environmental review, on behalf of Brown and Caldwell (BC), to identify significant hazardous material issues that could affect the construction, feasibility, and cost of proposed rehabilitation of the Metropolitan Water District (MWD) Prestressed Concrete Cylinder Pipeline (PCCP) portion of the Allen-McColloch Pipeline (AMP) in Orange County, California. Review of federal and California databases identified 53 sites where reported or potential unauthorized releases of hazardous materials or petroleum products could impact soil and/or groundwater within one mile of the PCCP alignment. Based on review of each of these releases, environmental sampling was recommended along five reaches of the PCCP, if excavation is needed, to: (1) assess the presence and composition of potential contaminants, (2) estimate the potential volume of contaminated soil that may be encountered, (3) estimate the potential volume of contaminated groundwater that may be removed (dewatered), (4) identify areas where methane and volatile organic compound monitoring should be adopted for worker safety during excavation activities, and (5) evaluate the feasibility and cost of managing hazardous materials that may be encountered.