City of Phoenix Cathodic Protection Surveys

Coffman was selected for a three year term contract to provide the City of Phoenix cathodic protection inspection services on their water distribution system. The project includes the survey and testing of both galvanic and impressed current cathodic protection systems for ductile iron, prestressed concrete, welded steel, and reinforced concrete pipelines.

The survey encompasses over 1200 test points, 900 of which are located near the City of Phoenix Valley Metro light rail transportation system. Since the majority of the test stations are located near the light rail, Coffman is tasked with evaluating both the assets and cathodic protection systems for signs stray current interference potentially coming from the light rail. Upon gathering and evaluating the data, Coffman will develop test plans or methods to test possible interferences from the light rail return current. In addition to the scope as stated in the RFP, Coffman improved data collection by setting up cooperative testing with Southwest Gas, obtained anode and pipe open circuit potential measurements, and provided submeter GPS locations for all test stations.