Millions of dollars are lost each year because of corrosion. Much of this loss is due to the corrosion of iron and steel from oxide formed by oxidation that does not firmly adhere to the surface of the metal. This flakes off easily causing pitting. Widespread pitting eventually causes structural weakness and disintegration of the metal. Many factors affect the rate of corrosion but the presence of water, moist conditions and hydrogen sulfide which are inherent to wastewater environment accounts for the fact that corrosion occurs much more rapidly at wastewater related facilities. As a part of the City of Columbus continuing efforts to preserve its investment in assets (buildings, process equipment, pumps, pipes, valves, supports, etc), the City hired Chester Engineers to assess the condition and provide recommendations for rehabilitation of the Southerly Wastewater Treatment Plant corrosion prevention and protective coatings systems.
The Interdisciplinary Approach
Chester Engineers worked to collect the field data needed for a systematic approach to the rehabilitation of the plants’ assets. Chester utilized SSPC and ASTM standards to rate plant assets such as process piping and equipment in each individual tunnel, building and other structures. The individual ratings were then used to give the tunnel/building/structure an overall ranking. The buildings and tunnels were then prioritized based on their overall rankings. Once the field survey was completed, Chester developed a budgetary cost estimate to allow the City to allot the necessary funds over the next three years to complete the coating rehabilitation at the Southerly WWTP. Chester then divided up the areas into the three phases starting with the highest ranking areas to approximately fit the allotted budget.
The Sustainable Result
Chester Engineers produced a set of bid documents for Phase 1 of the entire coating rehabilitation. The result for Phase 1 and the following Phase 2 and Phase 3 will be the protection of the plant’s assets for the next 10-15 years.