I filled a 6 yard skip with crushed concrete and soil once making sure that it was all compacted very well and every inch of capacity was used and that it wasn't 'too much' higher than the sides. When the lorry came to pick it up, the hydraulic support legs just sank straight through the 8 inch concrete in our back alleyway and made it rather awkward to pick up - he managed it after putting plenty of packers under the legs though. Franko.