The aim of this calculator is to help contractors and quantity surveyors estimate the material cost (bedding, infill material, and pipes) of installing different types of sewer pipeline systems. The calculator uses two possible classes of bedding for concrete pipes B and S and the single bedding class usually used for plastic pipes S.

About Bedding Classes The load bearing capacity of an installed pipeline relates directly to the construction of the bedding which is intended to level out any irregularities in the formation, and provide uniform support around and along the length of the pipe barrel. The strength of an installed pipeline depends on a combination of the strength of pipe and the class of bedding. The selection of the bedding class is influenced by many factors, which include the nature of the ground, the loads acting on the pipeline in the trench, the strength of the pipe, and the local cost and availability of the bedding material. Click on images opposite to enlarge.

Where imported granular material is expensive and where supervision of site work cannot be guaranteed, it is preferable to specify a lower class of bedding with a higher strength pipe, and this is the main reason why bedding material costs for concrete and plastic pipes are different. Class B is based on 180º granular bedding with selected backfill material, Class S requires full 360º granular bedding and therefore costs more (additional costs of bedding material with more Aggregate Levy paid per metre run of pipe laid, costs of excavated material transported from site, etc.)

The normally accepted classes of pipe bedding are shown in Table A2 and in Fig. A3 at CPSA Technical Guide No.1.
It should be noted that the cost breakdown is calculated as per metre run of pipe laid. To use the calculator you will need the following information:

• Size/ internal diameter (DN) of the pipe
• Cost of pipe (per metre run)
• Cost of material transported from site to landfill (per tonne)
• Unit cost of bedding used (per tonne).