Business Center

Structure Excavation Design Aid

TABLE 1
Excavation Rates for Flexible and Rigid Culverts
(Volume to be included in cost of culvert)
Inside Dia. Ba(inches) Flexible Pipes-Plastic and Metal Rigid Pipes-Concrete Flexible Pipe 0.3Ba Rate
(Cu. Yd./Ft.)
Rigid Pipe 0.3Bc Rate
(Cu. Yd./Ft.)
Rate/Ft.
(Cu. Yd.)
With 12" Bedding Bedding
Depth = 3"
Bedding
Depth = 12"
A B C D E F
15 0.36 0.51 0.45 0.57 0.06 0.10
18 0.42 0.59 0.53 0.65 0.08 0.13
24 0.56 0.75 0.69 0.83 0.11 0.14
30 0.71 0.91 0.88 1.04 0.15 0.20
36 0.89 1.11 1.09 1.26 0.20 0.24
42 1.08 1.32 1.32 1.50 0.26 0.32
48 1.30 1.56 1.58 1.77 0.31 0.38
54 1.53 1.81 1.85 2.06 0.38 0.45
60 1.78 2.08 2.15 2.37 0.45 0.53
66 2.05 2.36 2.47 2.70 0.52 0.62
72 2.33 2.66 3.81 3.06 0.60 0.72
78 2.64 3.00 3.17 3.43 0.69 0.82
84 2.96 3.33 3.55 3.83 0.78 0.93
96 3.67 4.08 4.38 4.69 0.98 1.16
 

Ba = Inside diameter of culvert Bc = Outside diameter of culvert.

Use Column A for structure excavation calculations for flexible pipes (metal and plastic) in soil trench when pipe is in a cut section. A cut section is defined to be when the final roadway template is above the top of the culvert by more than one foot. (See attached structure cross section).

Use Column B for flexible pipe trench in rock. Additional 12" of bedding material is required.

Use Column C for rigid pipes (concrete) in soil trench when pipe is in a cut section. Three inches of bedding material is required for all rigid culverts.

Use Column D for rigid pipes in rock trench when pipe is in cut section.

Additional 12" of bedding material is required.

Use Column E for all flexible culverts in fill section. A fill section is when the original terrain is below the 0.3 Ba line.

Use Column F for all rigid culverts in fill section. A fill section is when the original terrain is below the 0.3 Bc line.

The volumes obtained using Table 1 are to be included as "For Information Only" on the plans. This quantity is included in the cost of the culvert.

The rates in the Table are intended to save time and make the calculations easier. Use the table whenever possible. For example if you estimate that the average trench height for a 24 inch metal culvert is 18 inches, use half the rate in the table A since the table is based on a trench height of Bc + 1' or 36 inches. Since these volumes are for information only, a good, reasonable estimate is acceptable.

Structure Excavation to be paid for under the 206 Bid Item:

All structure excavation that is between the one foot above the top of the culvert line and the final roadway template is to be paid for as item 206-Structure Excavation.


Colorado: The Official State Web Portal