Interconnections and valve retrofit improvements were needed to the City of San Diego Mid-City water transmission pipeline. The project included construction of 855 linear feet of new 36 to 66 inch welded CML&C pipe. These sections were located in residential streets and in El Cajon Blvd, which is a major arterial roadway. TC Construction  procured and installed five, large diameter, custom made, triple offset butterfly valves. One valve was 36 inches in diameter, two measured 48 inches, and two measured 66 inches. A portion of the project had to be installed by constructing a 26 feet deep, 84 inch jack and bore tunnel under El Cajon Blvd. Completion of the project required extensive hydrostatic and operational testing prior to the connection to the adjacent San Diego County Water Authority flow control facility.