Stroygroup JSC concluded with a farm

Stroygroup JSC concluded a contract with the Kakhovskoye farm for dumping building rubble and materials from demolished houses at the site of future construction into a ravine on the farm´s territory. Crushed stone and materials were transported by a construction organization. For the export of crushed stone and materials, Stroygroup JSC paid a fee to the farm based on each cubic meter of cargo. When performing the work of Stroygroup JSC, it became known that the farm extracts metal fittings, pipes and other metal parts from dumped materials and sells them to organizations for the preparation of secondary raw materials. Stroygroup JSC filed a lawsuit against the farm for the reimbursement of income unreasonably received at the expense of another person. Can crushed stone be recognized as a product in this case? Is the requirement of Stroygroup JSC legitimate?