The pressure to deliver a cost effective drainage installation with minimum environmental impact has never been greater, but despite this, some pipelines are still fully surrounded in expensive imported granular bedding when a more considered approach to the design and selection of the pipe material could result in the use of a less costly, lower carbon installation.
There are various classes of bedding, providing varying degrees of support for the pipe. What is required will depend upon the material of the pipe, the surface load (traffic, weight of the ground and any overlaying fill) and the reaction from the ground below to support the pipe.
For structural design purposes pipe materials are classified – in BS 9295: Guide to the Structural Design of Buried Pipelines – as either rigid, semi-rigid or flexible. Concrete and clay pipes are defined as “rigid”; ductile iron and thick-walled steel are all classed as “semi-rigid” while thermoplastic, glass reinforced plastic and thin-walled steel pipes are all classed as “flexible”.
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The practice of carbon accounting for pipeline products and sewerage construction projects is not new, but PAS 2080 introduces something new. In this blog we identify how five carbon accounting principles in PAS 2080 will change the sector’s understanding of embodied carbon.
Many water companies, highway authorities, other drainage infrastructure asset owners and supply chain partners already employ project carbon calculators. However, there are significant differences between these tools. PAS 2080 introduces a structured approach to tackle this inconsistency problem: It also provides clear boundary rules and a framework for whole life carbon accounting based on European standard EN 15978 where carbon claims can be verified and low carbon solutions can be robustly assessed.
PAS 2080 could mark the end of unproven claims for manufacturers of pipeline products. Data sources such as the Bath University ICE database will no longer be the main source of embodied carbon data. For manufacturers, PAS 2080 introduces five main principles which will change how embodied carbon is dealt with: These are
- Consistency in methodology
- The ‘Cradle-to-Grave’ approach
- Data Quality Requirements
- Third party accreditation
- Data challenging and re-baselining
FIVE FACTS THAT MAKE PAS 2080 DIFFERENT
PAS 2080 states “Consistent methodologies and data sources for carbon management and assessment are to be used to allow comparisons of emissions over time”. Users are obliged to assess inconsistencies and continuously challenge their suppliers for more accurate and robust data. The standard doesn’t embrace a specific methodology but European standard EN 15978 indicates that the European Commission’s TC350 methodology is probably the route to be taken by any future revision of PAS 2080. This means that the Bath University ICE Database may no longer be an automatically valid option as it compiles carbon values from a wide range of studies that are not aligned to EN 15978 requirements.
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Published by the Treasury in late 2013 the Infrastructure Carbon Review documented the prospect of infrastructure value chain participants to collaborate in the expansion of low carbon infrastructure developments.
PAS 2080:2016 Carbon management in infrastructure was commissioned to facilitate this into reality. Mott McDonald and Arup developed the standards with support from the Green Construction Board (GCB). Figureheads within the infrastructure sector described the new standard as a ‘game changer’ which will pave the way for ‘consistency of methods and reporting’ across the supply chain.
It is specifically targeted to decision makers (asset owners/managers, designers, constructors and material suppliers) PAS 2080 provides a regular framework on how to manage whole life carbon when delivering infrastructure assets.
Manufacturers should take note that PAS 2080 introduces a new requirement for providing precise carbon data for their products, which ideally is 3rd party accredited. This puts emphasis on the whole life evaluation and through its adoption of boundary defined modular approach, carbon assessments now need to be more inclusive than ‘Bath University ICE database’ assumptions. In order to become a more reliable, representative and transparent format, similar to the one used in standards such as EN 15978 and ISO 21930.
You can also find PAS 2080 is available at the BSI Website for £100 HERE
THE CARBON FOOTPRINT OF CONCRETE PIPES
In 2010 we commissioned Carbon Clear consultancy to consider the performance of precast concrete pipes and manholes with their plastic counterparts. The study concluded that concrete pipes’ carbon footprint was 35% lower than the plastic alternative.
Credited to: Hafiz Elhag, Sustainability Manager, British Precast
In 2015 the planning regulations in England and Wales were amended to ‘expect’ Sustainable Urban Drainage Systems (SuDS) to be included in all new housing developments of 10 or more homes.
SuDS is about dealing with rain where it falls, this is in contrast to conventional drainage solutions which carry run-off from a development to an outfall as quickly as possible.
To deal with the surface water where it falls clients, designers and installers have the option of using hard and soft SuDS solutions. Hard SuDS include proprietary engineered products installed underground such as precast concrete soakaways, attenuation tanks and treatment chambers whereas soft SuDS are generally landscaped, vegetated features such as swales and detention ponds.
Soft SuDS are a useful starting point when considering design options because they can provide amenity to a development. The downside is that vegetated features often require larger areas of land, land that could otherwise have been used for development. By contrast, proprietary solutions such as precast concrete underground systems help ameliorate run-off without using valuable land. A balance of both hard and soft SuDS components is often the most appropriate and cost effective sustainable drainage solution.
Hard SuDS solutions can help developers manage surface water run-off without using up valuable development land explains Stuart Crisp, Business Development Director at the Concrete Pipeline Systems Association (CPSA).
To help introduce customers to sustainable drainage principles and precast concrete SuDS components, the CPSA has produced an accredited, free CPD seminar entitled Surface Water Management using Proprietary Precast Concrete SuDS systems.
The Concrete Pipe Lifter is a safer way to offload, handle and install pipes whilst simultaneously speeding up operations and reducing costs. You simply attach it to your excavator using the quick–hitch coupling. The Pipe Lifter has no slings or chains that hands could get trapped in, and requires no additional power requirements or hydraulic links. By removing people from the process, the risk of harm is eliminated. Nobody is needed on the vehicle during offloading and nobody is needed in the pipe trench during jointing. We’ve published a factsheet on the risks of manual handling in accordance with HSE’s best practices. It concludes that pipes of any material DN300 and over should be mechanically lifted.
Concrete pipeline systems have been part of the backbone to the UK’s sewerage network for over 150 years for good reason. The inherent strength of precast concrete products, their durability and their availability in a wide choice of sizes and cross-sectional shapes has made them a favourite choice. This blog adds some of the detail behind the headlines in our Heavyweight campaign.
The reasons concrete products were selected for use in drainage systems over a century ago are as valid now as they were then. But in today’s competitive drainage market the lower installed cost and whole life cost benefits resulting from their long service life coupled with excellent environmental credentials is ensuring precast concrete drainage products are still in favour with today’s engineers, contractors and asset owners.
Installed cost savings can be significant. For example, because concrete pipes are structural elements they can often be laid without the need for a full granular bedding surround. This may also save on installation time. It also means the quantity of imported granular material can be kept to a minimum while providing the opportunity to reuse excavated material, saving on disposal costs. And, once placed in the pipe trench, the inherent weight of concrete products ensures that they offer a natural resistance to flotation.
Despite the heavy weight of concrete pipes, using the award-winning pipe lifter can make unloading pipes from the delivery vehicle and the installation process up to half the time of traditional methods and, most importantly, safe as no-one is required on the vehicle or in the trench during the operation.
In addition to saving money, the inherent strength of concrete pipes makes them the preferred choice where loads from traffic running over the buried pipeline are significant. Their strength also makes them the preferred choice for deep installations where greater ground loads are imposed on a pipe.
Once installed the advantage of concrete pipeline products is immediately apparent. They do not deform or lose shape over their service life which ensures their hydraulic efficiency and structural integrity is maintained. They are also more resilient to damage from maintenance using high-pressure water jetting compared to many lightweight systems.
Concrete pipes also offer some major advantages when it comes to environmental sustainability; for example they are made from responsibly sourced local materials. In fact, a study by the CPSA and Carbon Clear demonstrated that a DN2100 concrete pipe has up to 35% lower embodied carbon on a like-for-like Class S cradle to site basis compared to the same size HDPE pipe.
Modern drainage asks for so much from its materials that it is clear that this is not a job for a lightweight. What is needed is Concrete, the Heavyweight Champion of the Drainage World.
The introduction of asset management period six, known as AMP6 by industry regulator Ofwat has seen water company costs measured on a total expenditure basis for the first time, which requires the proper consideration of the long term performance of assets in addition to capital cost efficiencies.
The five year period of AMP6 between April 2015 and March 2020 aims to increase the efficiency of asset management without increasing costs for consumers.
Under previous asset management periods, water companies have tendered contracts to construction firms to update some of the company’s assets and to keep existing infrastructure properly maintained for the five-year duration of the AMP. Ofwat, however, was concerned that under these AMPs water companies may have been using capital expenditure (capex) to build assets, such as water treatment works, to make a business more valuable for its shareholders rather than on reducing operational expenditure (opex) to deliver better value to customers.
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This blog focuses on deflection of flexible (e.g. plastic) sewer pipelines and aims to inform the reader so that appropriate decisions can be made when designing, specifying, buying, installing and operating a sewer pipeline.
It is vitally important that users understand the differences between flexible pipes such as plastic and rigid pipes such as concrete and to appreciate how these materials perform in terms of structural integrity and hydraulic efficiency.
CPSA has produced a number of publications covering this subject, all of which can be downloaded free of charge on our web site.