 The World War II facility used forced labor of the Schlier-Redl-Zipf subcamp of the Mauthausen-Gusen concentration camp and included a liquid oxygen generation plant in a nearby tunnel.After an August 1944 explosion at the liquid oxygen plant stopped Schlier production, the third V-2 liquid oxygen plant (5000 tons/month) was built at a slate quarry at Lehesten near the Mittelwerk (turbopump/chamber compatibility testing for Mittelwerk production was also performed at the Lehesten facility).Karl Heimberg, who had worked at Peenemünde Test Stand 7, was transferred to ""Vorwerk Sued"" at Redl-Zipf and then, for the period from late 1944-early April 1945, to Lehesten (he later returned to Peenemünde with Walter Riedel III to burn design office files and participated in the post-war Operation Backfire.)