Contra Costa Water District
Contra Costa Water District has over 800 miles of pipeline in the ground, of which approximately 20 miles of steel pipeline are installed in high traffic areas, with limited or no cathodic protection. The objective of this assessment was to identify the corrosion protection needed to prolong the service life and system reliability of approximately 20 miles of steel pipelines. The pipelines of concern were installed between 1950 to 1995 — with limited or no corrosion protection — and most are located in high traffic areas making repairs difficult. Most of these pipelines were installed with rubber gasket joints (not welded), which make the pipelines electrically discontinuous and expensive to retrofit with corrosion protection.
This assessment included an evaluation of soil and pipe characteristics to identify which pipelines were susceptible to corrosion. The subject pipelines are primarily mortar-coated steel or asphaltic-coated steel pipe. There are also two short sections of ductile iron pipelines. Sections of pipe in areas with highly corrosive soils were excavated and examined. The pipeline contract drawings were reviewed in order to determine the steps that were taken during the original construction to protect the pipe, such as applying cement mortar coating over dielectric-coated steel at pipeline joints.
This was a very large project with a significant budget and a challenging schedule. Our firm completed this project on-time and under budget.
Zone 7 Water Agency
Project: Development of an overall corrosion control program and develop a GPS coordinate database for all test stations and Cathodic Protection system components.
This project involved the development and implementation of a comprehensive corrosion control program for the Zone 7 Water Agency. The Zone 7 Water Agency facilities/structures consist of 2 water treatment plants as well as over 50 miles of water transmission pipelines of various diameters, several clear wells, and numerous water wells and water storage tanks. The Zone 7 Water Agency cathodic protection system consists of both impressed current and galvanic anode systems. All of the major mortar-coated steel transmission pipelines are provided with either a cathodic system or a corrosion monitoring system.
A GPS coordinate database was created for all coal tar coated steel pipelines and the corrosion monitoring systems for the cement mortar coated steel pipelines owned and operated by the Alameda County Flood Control and Water Conservation District, Zone 7 Water Agency. The structures covered by this project are located in Dublin, Pleasanton and Livermore, CA. The cathodic protection systems consist of a combination of impressed current and sacrificial anode type cathodic protection systems for external corrosion protection of the pipelines. The structures, which were surveyed and included as a part of this database, consisted of approximately 160,000 feet of water transmission pipeline.
Project: Inspect internal coating system for export pipeline
Our firm conducted a coating evaluation of the interior of the export pipeline for LAVWMA. The purpose for this inspection was to assess the condition of the western most section of the LAVWMA Export Pipeline where it extends into the marshland area and connects to the East Bay Dischargers Authority (EBDA) interceptor in San Lorenzo. This condition assessment consisted of internal inspection of the pipeline via four vaults. The coal tar enamel lining was disbonded from the interior surfaces of the pipeline in large areas (reported up to 50% loss of coating coverage) and the underlying steel pipe was actively corroding at a rate which is common for all mild steels when exposed to fresh water.