The standard ČSN 73 30 50 divided soil into a total of 7 following classes. The summary gives a simplified feature.

ClassSoil characteristics
1Compact soil of soft consistency and incompact loose soil with gravel grains up to 5 cm (max. 10 % volume)
2Compact soil of ridgit consistency and medium lying down of soil with gravel grains up to 10 cm
3Compact soil of solid - ridgit consistency, clay soil with soft – ridget consistency and incompact lying down of soil, gravel grains up to 10 cm, cement gravel and weathered rock
4Clay gravel solid – ridget consistency, rough gravel with grains up to 25 cm and bouldery component up to 0,1 m3, gravels with clay cement, weathered rock
5Rough gravel grains 10 – 25 cm, incompact soil of 4 th class with clay cement solid consistency. Healthy weathered rock
6Strengthened weathered rock, incompact soil with bouldery up to 0,1 m3
7Healthy rocks

Accurate definition of 1st class according to KOPOS KOLIN a.s. recommends that the KOPOFLEX and KOPODUR shields are covered with soil with grains up to 50 mm in a maximum volume of 10% in soil. The detailed conditions are determined by EN 1610, which replaces an already invalid ČSN 73 30 50. Here is a description of the soil, which is already ivalid according to the standard but it describes the exact nature of the soil.

a) Compact, soft consistency. E.g. arable land, clay, sand clay, muddy sand
b) incompact, loose grains of up to 20 mm with grains over 20 to 50 mm in volume up to 10% of the total volume of first class soil eg sand, sand with gravel, sand gravel, small and medium gravel or gravel with stones
c) construction waste and weights of a similar nature to soil classified as first class