Semen Berlyant was a Ukrainian Jew working on a German-run farm near Kiev during the war. In early September 1943, he was taken from there to Babi Yar, a place where tens of thousands of Jews are said to have been shot and buried by the Germans in mass graves in late September 1941 (see the entry on Babi Yar). He was interrogated by the NKGB on 16 November 1943 about his alleged experiences at Babi Yar.
Among other things, Berlyant stated that he and some 320 other slave-labor inmates were put in chains and had to exhume mass graves and burn the extracted bodies on pyres. Those pyres had 300 corpses in one layer, alternating with layers of wood, with a total of 3,000 bodies per pyre. This results in ten layers.
Let’s assume that a running meter of a pyre two meters wide can accommodate four corpses. Each corpse requires 250 kg of freshly cut wood (see open-air incinerations). The density of green wood is roughly 0.9 tons per m³, and its stacking density on a pyre is 1.4 (40% for air and flames to go through). This means that the wood required to burn just one layer of corpses is some 0.75 meters high. Adding the body layer gets us to roughly a meter. Ten such layers result in a pyre ten meters high. It would have been impossible to build such a pyre, and also impossible to burn it down without it collapsing and spilling burning wood and corpses all over the place.
Berlyant claimed that in total 70,000 corpses were burned at Babi Yar. Cremating 70,000 bodies thus requires some 17,500 metric tons of wood. This would have required the felling of all trees growing in a 50-year-old spruce forest covering almost 39 hectares of land, or some 87 American football fields. An average prisoner is rated at being able to cut some 0.63 metric tons of fresh wood per workday. To cut this amount of wood within the five weeks this operation is said to have lasted (35 days) would have required a work force of some 800 dedicated lumberjacks just to cut the wood. Berlyant claims his unit consisted only of 320 inmates, all busy digging out mass graves, extracting bodies, building pyres, and according to other testimonies, also sifting through ashes, scattering the ashes and refilling the graves with soil. Berlyant says nothing about where the firewood came from.
Berlyant also asserted that people murdered in gas vans were brought to Babi Yar for cremation. However, considering that the front was getting very close to Kiev during September 1943, it is unlikely that anyone would have operated gas vans in Kiev’s vicinity. All this apart from the fact that gas vans are a figment of Soviet atrocity propaganda (see the entry on gas vans).