Mitigation particle deposition

The question of durability of the mitigation system arises not only from the need for lifetime operation in the house, but also from concerns about the environment to which the SSD system is subjected.13 15 Soil gas is often very humid, causing condensation problems in the piping and the fan of the mitigation system. Also, particles can be drawn from the gravel bed or soil they in turn may line the pipes and deposit on the fan or possibly interfere with the fan bearings. 

Particle trapping is also a substantial economic issue, as in many countries the sUtation time scale is relatively short (about 100 yr on a global scale). In alpine reservoirs this time scale is much longer, and measures to mitigate siltation had low priority. However, in the future, sediment management, including removal, will be unavoidable. An occasionally used method is to divert the early arrival of a turbid flash flood past the reservoir, so that most of the sediment is delivered to the downstream river. Also, sediment removal and downstream re-deposition is periodically applied, especially when the downstream river suffers from erosion. 

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