introduCtion Durability Considerations Durability of a pipe material is as significant as its ability to perform intended structural and hydraulic functions. The capability of the pipe to continue to perform satisfactorily for an economically acceptable period is a fundamental engineering consideration. Unfortunately, predictions of durability cannot be made with the same degree of precision as can structural and hydraulic performance, and, in too many instances, durability is not accorded adequate consideration. At the present time, there is no known material completely inert to chemical action and immune to physical deterioration. Concrete is no exception, but, under what might be considered normal conditions, it has a very long life. Durability is concerned with life expectancy, or the endurance characteristics of a material or structure. In no type of facility is long term integrity more critical than in sewer lines and culverts. Much attention has been directed to the durability of pipe, but the vagaries of climate, soils and geology, fluid impurities, construction materials, and the construction process itself prevented the development of a systematic and practical theory for predicting performance. The problem has been compounded by the assumed requirement that pipe must last almost indefinitely. Concrete pipelines have a long history of excellent durability, and it is unlikely this record will change. Pipelines are beneath the ground where temperatures have very little variation, where atmospheric exposure is either not present or greatly reduced, and where the materials in close proximity to the pipe are usually nonaggressive. Laboratory test results, and damage records for cast-in-place concrete that has been exposed to atmospheric conditions, should not be related to buried precast concrete pipe until it is determined that comparable conditions will exist. Improper application of data could lead to overdesign and excessive cost. ConCrete pipe stormwater treatment teChnologies box seCtions manhole and CatCh basin material LAFARGE PIPE eMANUAL PAGE 45