bacteria including aerobic and low nutrient. Certain types of bacteria( thermophiles)have been found to survive significantly high temperatures Conclusion. An evaluation of the cathodic protection system showed the design to be adequate provided it was eliably powered. Cathodic protection is one means of controlling MIC, although interruption in the cathodic protection service will adversely affect its performance. The effectiveness of the cathodic protection on established microbial deposits is questionable Recommendations. The tank floor was ultrasonically tested, and portions of the floor replaced based on the remaining wall thickness. Doubling the wall thickness of the replacement floor plates was recommended Example 3: Preventive Maintenance for Buried Pipelines. Corrosion is a major contributor to the deterioration of buried infrastructure such as pipelines in the United States. Figure 4 shows the result of an unexpected corrosion failure of a 100-year-old riveted steel water transmission main. The snowplow and icing of the power lines in the photograph indicate that repairs had to be made under less than ideal weather conditions. The costs associated with the evaluation, modifications, and cathodic protection of a water system typically represent less than 10% of the total cost to replace the buried infrastructure. These savings can be obtained through the implementation of a comprehensive corrosion-control program 一爬 Fig 4 Corrosion failure of 100-year-old riveted steel water transmission main Courtesy ofs. Paul Corrtech. inc To ensure that the proper corrosion-control method(s)are employed and the full infrastructure service life is realized, local factors contributing to corrosion must be understood. Where history or analyses indicate that the environment is aggressive, corrosion-control methods need to be developed and initiated. To evaluate corrosion-exposure conditions for metallic piping networks, field conditions such as soil type, soil pH, stray current effects, and electrical continuity require quantification by field investigationbacteria including aerobic and low nutrient. Certain types of bacteria (thermophiles) have been found to survive significantly high temperatures. Conclusion. An evaluation of the cathodic protection system showed the design to be adequate provided it was reliably powered. Cathodic protection is one means of controlling MIC, although interruption in the cathodic protection service will adversely affect its performance. The effectiveness of the cathodic protection on established microbial deposits is questionable. Recommendations. The tank floor was ultrasonically tested, and portions of the floor replaced based on the remaining wall thickness. Doubling the wall thickness of the replacement floor plates was recommended. Example 3: Preventive Maintenance for Buried Pipelines. Corrosion is a major contributor to the deterioration of buried infrastructure such as pipelines in the United States. Figure 4 shows the result of an unexpected corrosion failure of a 100-year-old riveted steel water transmission main. The snowplow and icing of the power lines in the photograph indicate that repairs had to be made under less than ideal weather conditions. The costs associated with the evaluation, modifications, and cathodic protection of a water system typically represent less than 10% of the total cost to replace the buried infrastructure. These savings can be obtained through the implementation of a comprehensive corrosion-control program. Fig. 4 Corrosion failure of 100-year-old riveted steel water transmission main. Courtesy of S. Paul, CorrTech, Inc. To ensure that the proper corrosion-control method(s) are employed and the full infrastructure service life is realized, local factors contributing to corrosion must be understood. Where history or analyses indicate that the environment is aggressive, corrosion-control methods need to be developed and initiated. To evaluate corrosion-exposure conditions for metallic piping networks, field conditions such as soil type, soil pH, stray current effects, and electrical continuity require quantification by field investigation