Leeds based ground worker and civil engineer, Athena Civil Engineering, has taken the initiative on a new housing development in Roundhay, near Leeds, to reduce the amount of primary aggregate used on the pipe drainage works. This is in line with industry guidelines which indicate that using a full surround class ‘S’ granular bedding in conjunction with large diameter precast concrete pipes is often over specifying the buried pipeline design.
Working on behalf of housing developer Chartford Homes at their new Hampton Park site, Athena has constructed a storm attenuation tank using FP McCann’s large diameter reinforced concrete spigot and socket pipes. By adopting a class ‘B’ embedment design, Athena has achieved significant cost savings and minimised environmental impact on site without sacrificing installed performance of the completed pipe system.
The attenuation tank set out in four pipe runs consists of 21 standard DN1800 2.5 metre spigot and socket pipes, 4 DN1800 pipes with end caps and 4 DN1800 pipes with end caps and cast in side entry access.
Using the Concrete Pipeline Systems Association (CPSA) structural design and material cost calculators based on BS 1295-1 “The structural design of buried pipelines”, Athena were able to determine the optimum bedding design to adopt for the project and calculate the cost benefits versus a plastic system with a full Class ‘S’ granular surround. Key inputs into the model included pipe sizes and comparative costs and imported granular material prices. Consideration was also given to the trench excavated material which was deemed suitable for final backfill purposes.
Commenting on the installation, Jonathan Hotham, Project Manager for Athena Civil Engineering said, “We had every intention of using plastic pipe on this project, but when FP McCann’s Area Manager, Igor Skoro, took us through the CPSA structural design and material cost calculators, it gave us the opportunity to present a more cost-effective and efficient approach to the job for our client and builder, Chartford Homes, who took on board our proposal. We shall certainly be using the CPSA material cost calculator on future schemes and a closer consideration of pipe choice, in conjunction with bedding options, will be something we’ll continue to develop.”
The CPSA Structural Design Calculator can be accessed via www.concretepipes.co.uk /calculators/material-cost