Soil Classifications

The following ASTM D2487/US Bureau of Reclamation Soil Groups classify different soils for embedment, i.e., soils which are used for placement in the trench surrounding the pipe, compacted or uncompacted, to provide support for the pipeline. These groups classify naturally occurring soils as well as manufactured materials. The groups are also for use in classifying undisturbed trench wall materials.

GROUP A -- Angular graded stone (6mm - 40mm), including a number of fill materials that have regional significance, such as crushed stone, crushed gravel, and crushed shell.

GROUP B (GW, GP, SW, SP ) -- Coarse-grained soils with little or no fines, no particles larger than 40mm, including a number of fill materials that have regional significance which have rounded grains, such as pea gravel.

GROUP C (GM, GC, SM, SC, CL, ML, ML-CL, CL-CH, ML-MH ) -- Coarse-grained soils with fines and fine-grained soils with medium to no plasticity, with greater than 25% coarse particles, liquid limit (LL) less than 50%.*

GROUP D (CL, ML, ML-CL, CL-CH, ML-MH ) -- Fine-grained soils with medium to no plasticity, with less than 25% coarse particles, liquid limit (LL) less than 50%.*

GROUP E (CL, MH, CH, MH) -- Fine-grained soils with medium to high plasticity, liquid limit (LL) greater than 50%.

GROUP F (PT) -- Organic soils.

*Designer must determine percentage of coarse particles to accurately determine soil group.

INT Maximum Recommended Depths of Cover (m) (Access Roads, Soil Type C, Bedding in 100mm Loose Material)

Maximum Recommended Depths of Cover (m) (Access Roads, Soil Type C, Bedding in 100mm Loose Material)
Nominal Size (mm)	Class	Trench Type II	Trench Type III
100	K9	40	40
150	K9	18	19
200	K9	12	13
250	K9	9.9	10
300	K9	8.4	9.4
350	K9	7.4	8.6
400	K9	6.7	8
450	K8	4.9	6.4
450	K9	6.3	7.9
500	K8	4.6	6.3
500	K9	5.9	7.3
600	K7	3	4.9
600	K8	4.4	6.2
600	K9	5.4	7
700	K7	2.7	4.6
700	K8	3.9	5.7
700	K9	5.1	6.7
800	K7	2.5	4.4
800	K8	3.5	5.4
800	K9	4.9	6.6
900	K7	2.4	4.3
900	K8	3.3	5.2
900	K9	4.5	6.3
1000	K7	2.3	4.2
1000	K8	3.1	5
1000	K9	4.2	6
1200	K7	2.1	4.1
1200	K8	2.9	4.7
1200	K9	3.9	5.7
1400	K7	2	4
1400	K8	2.7	4.6
1400	K9	3.6	5.4
1500	K7	2	4
1500	K8	2.7	4.5
1500	K9	3.5	5.3
1600	K7	2	3.9
1600	K8	2.6	4.5
1600	K9	3.4	5.2

INT Maximum Recommended Depths Of Cover (m) (Main Roads, Soil Type C, Bedding in 100mm Loose Material)

Maximum Recommended Depths Of Cover (m) (Main Roads, Soil Type C, Bedding in 100mm Loose Material)
Nominal Size (mm)	Class	Trench Type II	Trench Type III
100	K9	40	40
150	K9	18	19
200	K9	12	13
250	K9	9.7	10
300	K9	8.2	9.3
350	K9	7.2	8.4
400	K9	6.5	7.8
450	K8	4.6	6.2
450	K9	6	7.4
500	K8	4	6.1
500	K9	5.6	7.1
600	K7	2.3	4.6
600	K8	4	5.9
600	K9	5.1	6.8
700	K7	*	4.3
700	K8	3.5	5.5
700	K9	4.8	6.5
800	K7	*	4.1
800	K8	3.1	5.1
800	K9	4.6	6.4
900	K7	*	4
900	K8	2.8	4.9
900	K9	4.2	6.1
1000	K7	*	3.9
1000	K8	2.6	4.7
1000	K9	3.9	5.8
1200	K7	*	3.7
1200	K8	2.3	4.5
1200	K9	3.5	5.4
1400	K7	*	3.7
1400	K8	2.1	4.3
1400	K9	3.2	5.2
1500	K7	*	3.7
1500	K8	2.1	4.3
1500	K9	3.1	5.1
1600	K7	*	3.6
1600	K8	2	4.2
1600	K9	3.1	5

Notes:
*Type III Trench should be used for this condition.