In order to prevent pollution of the Caspian Sea the Company uses stepped steel structures with a special filling material that reinforce the coastline against landslides. These are known as ‘Reno mattresses’. At the Teren-Uzek and Zapadnaya Prorva deposits of NGDU Zhylyoymunaigas some 8.6 km of protective dam is being reinforced. As part of the industrial environmental control programme, the quality of sea water and seabed deposits are monitored annually at seven control points; the condition of sea wells is studied monthly; and samples are taken quarterly and certificate of inspection are issued.