Øvre slamdam

Det blei drive forsøk med flotasjon på Flåt gruver frå 1916, men kapasiteten var liten. Etter at flotasjonsanlegget brann ned i 1929, blei det bygd anlegg med mykje større kapasitet. Dette ureina vass­draget så mykje at det blei reist rettssak mot Raffineringsverket NS på 1930 talet.

Øvre slamdam blei bygd kring 1934. Dei lasta fyllkasser i dei store stein­tippane og køyrde ut stein med seks lastebilar og fleire hestar. Selskapet kjøpte myra nord for gruva til vassbasseng. Der skar dei ut torv til tet­ting av demninga. Nokre gonger rauk slamdammen. Då blei Otra far­ga brun heilt ned mot Hægeland, 25 km sør for Evje.

Upper sludge pond (from 1934)

Flotation was tried from 1916, but with small capacity. The flotation plant burned in 1929, and a new plant with much larger capacity was built. This contaminated the local river system to such extent that it led to a trial against Raffineringsverket around 1930. 

The upper sludge pond was built in 1934. Grates were loaded with rock at the tip and freighted by six trucks and several horses. The company had bought a marsh for water reservoir, and peat was cut from here and used to seal the dams with. 

At times the dam would break. Otra was then coloured brown with sludge all the way to Hægeland - 25 km south of Evje.

Publisert 23.10.2025 10:32