Some simple studies of completing water supply from Lake Brusdalsvannet, Ålesund Municipality

Sammendrag

Ålesund city wants to make their water supply more secure by building a new independent waterworks that can be operated as a main waterworks, or as reserve-, or in practical cooperation with the existing one. The intake should be put at 50 m depth offshore from Reitane on the northern shore, or outside Uraneset, also at 50 m depth, on the southern shore of the lake. If the Reitane intake alternative is chosen, the water treatment plant could be put on ground close to the lake. This would be the cheapest in case of the new facility mainly should be used as reserve. If the new facility should be used as a main water supply unit for longer periods, it could be better to put the treatment facility higher up in the hillside to be able to distribute water by gravitation instead of pumping. A subterraneous solution would add more security. If the intake outside Uraneset is chosen, it would likely be best to have the treatment plant at Litlestølen not far from the existing water treatment plant, and have the intake pipeline going in-lake instead of on-shore. The new pathway for the E39 should be along the Ellingsøy Fjord, and not along Lake Brusdalsvatn. With respect to sewage remediation in recreation areas and areas of scattered dwellings along the Lake Brusdalsvatn, the best method seems to be a system of collecting the toilet water (black water) in water tight tanks with contractual emptying, whereas the wash water (grey water) being treated in grey water treatment facilities.