a major problem was sewage: most of london's waste was allowed to flow into the thames resulting in a horrendous smell in the summer months. in 1855 and 1858 there were especially bad summers with the latter being known as "the great stink". a notable achievement of the board was the creation of the core london sewerage system, including 75 miles (120 km) of main and 1000 miles (1650 km) of street sewers, which solved the problem. a large part of the work of the mbw was under the charge of the chief engineer, joseph bazalgette, previously engineer with the metropolitan commission of sewers.