Concrete Pipes

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Precast concrete drainage technical guide revised to align with new standards for pipelines structural design

The British Precast Drainage Association (BPDA) has published a new edition of its precast concrete drainage sector Complete Technical Design Guide. Several amendments were made to the Guide and new content was introduced to meet the requirements of the revised pipeline structural design standard, BS 9295, published last year. The Technical Guide revision comes at the back of an earlier overhaul we carried out in 2019 to include further content on hydraulic design, Eurocodes compliant loading and new chapters on the structural design of box culverts.

The new 2021 edition is now fully aligned with all the principal design changes introduced in BS 9295. These include the addition of a “wide trench condition” method to rigid pipelines’ design, new bedding factors, Eurocodes-aligned traffic loading and a new design option based on Limit State Design. Further changes were also introduced to align the standard with the new DCG sewers adoption guide and latest government advice on CE Marking and post-Brexit UKCA mark.

A copy of the new Technical Guide can be downloaded from our website, here:
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It’s a winner! Latest pipe jetting resistance test proves Precast Concrete Pipes as most reliable

Compared to various plastic pipe alternatives, concrete pipes are more likely to withstand a blockage clearance operation requiring 4,000 psi water jetting, a typical high‐pressure jetting range used regularly by contractors to clear some of the most challenging sewer blockages. This is according to results from a series of jetting resistance tests published by BPDA. On the other hand, it could take no more than 3 to 5 seconds for some plastic pipe alternatives to experience irreversible piercing damage when cleaned at the same water jetting pressure.

BPDA carried out a series of high-pressure stationary water jet tests in late 2019. Eight samples of concrete and plastic pipes were included. The tests were carried out with a jetting pressure of 4,000 psi, a water jet pumping pressure range not recommended for all types of pipes but frequently used by cleaning contractors to clear some of the most challenging sewer blockages involving fatbergs, wipes, rags and tree roots.

As a precaution, and to avoid damage from high-pressure jetting, the Manual of Drain & Sewer Cleaning advises that the jetting nozzles should not be kept stationary at one single spot for more than 90 seconds. It was, therefore, reasonable to expect some resistance from all types of pipes (including plastic) to high-pressure stationary jetting that would last for at least 30 to 60 seconds. However, in almost all plastic pipe samples tested, this was not the case. Four of the six plastic pipe samples all experienced significant internal layer piercing damage inside 5 seconds. The pipe walls in all four samples were fully penetrated within a few seconds. One sample experienced significant internal layer piercing damage inside 3 seconds only, raising fears that any potential blockage clearance where high-pressure jetting is the only option may result in permanent damage and replacement or rehabilitation for such types of pipe.

The other two plastic pipe samples, currently being advertised as resistant to 4,000 psi jetting, also experienced significant piercing damage to the inner surface within 5 to 60 seconds. In both samples, the jetting water dispersed through the core material within the pipe wall, exposing the recycled core material and raising blisters on the inner surface. All the concrete pipe samples tested passed the test.

Colin Richardson, President of BPDA, noted that these test results should serve as warning to the industry about the risks of deregulation. The new Water industry sewers adoption code no longer allows water companies to impose their own restrictions and rules on sewers adoption. At least three Water Companies used to restrict adoption to sewerage pipes that can resist high-pressure water jetting up to 4,000 psi. “Every year, Water Companies deal with up to 300,000 sewer blockages across Britain”, he noted, “it is fully acknowledged that consumer’s behaviour needs to change. But there is more that we can do as an industry to ensure that our sewerage systems are capable of withstanding the implications of a sewer blockage clearance”. Colin Richardson believes that all Water Companies need to introduce strict limits to pipes’ jetting resistance.

Results of the test report can be found here.
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Lack of verified sewerage & drainage pipes carbon data can jeopardize efforts to address Climate Change in the sector

Ten years on since we published the first third party verified carbon footprint for UK manufactured concrete pipes and manholes, the drainage & sewerage sector continues to struggle with the availability of verified and representative carbon data for certain construction products and components. The case for pipeline products is specifically concerning: While the UK concrete drainage sector have representative and 3 rd party verified carbon footprint data accurately reflecting their supply chain, the situation with the carbon data for other types of pipeline products is completely different as non-representative supply chain data is still being used.

Ten years ago, BPDA was one of the first construction product sectors to publish a 3 rd party verified carbon footprint for concrete pipes and manholes to standard PAS 2050. BPDA members would then introduce a wide range of measures and initiatives to reduce carbon, from precast base manholes to a number of concrete pipes lifting and installation equipment designed to improve H&S and reduce emissions from traditional installation methods. The EPD we published in 2018 revealed a 9% reduction to the carbon footprint of concrete pipes.

In 2011, there was very little attention to this topic within the sewerage and drainage sector. Today, the situation is totally different. An Infrastructure Carbon Review in 2013, first launched with Government support, resulted in the development of a new Carbon Management guidance standard for the industry, known as PAS 2080. A number of Water Companies today operate sufficient carbon accounting systems to ISO 14064 and Water UK has even launched a carbon routemap to 2030.

However, in order to properly assess and quantify the Capital Carbon of water & wastewater projects, there is a need for robust and reliable embodied carbon data for different products and materials in accordance with recognised methodologies. PAS 2080 identifies a number of specific methodologies. Only verified EPDs or Carbon Footprints to EN 15804, ISO 21930, ISO 14067 or PAS 2050 can be used. Such EPDs will need to be representative of the components, products and technologies employed. The carbon data needs to be “regionally applicable” and “reflect the technologies used in the supply chain” of that project. For a pipeline study to be acceptable under PAS 2080, there is need for these representativeness requirements to be fulfilled.

Unfortunately, this is currently not happening. While the UK’s concrete pipe sector has so far published at least three carbon footprint reports to PAS 2050/ EN 15804 and three 3 rd party verified comparative studies, the UK’s plastic drainage sector has not made any UK-specific carbon footprint data publicly available. The plastic pipe industry across all Europe currently has a single set of data covering the entire sector. The data is believed to be reliant on earlier plastic resin studies by Plastics Europe which are based on 100% European resin production. This may no longer be the case in the EU or UK market as some evidence suggests that imported HDPE resin already makes a significant proportion of resin consumed in the EU (JRC, 2020). A JRC study last year suggested that almost two thirds of all plastic resin imported to the EU comes from the Middle East where completely different energy sources and technologies are employed (see Table 4.6 here). If it turns out that plastic drainage manufacturers continue to use Middle Eastern resin, then this should reflect on their generic carbon footprint (currently based on an old study carried out 15 years ago). Last year, a study conducted by Circular Ecology for BPDA revealed that an HDPE pipe manufactured from Middle Eastern resin can have a carbon footprint 33% higher than one made of resin imported from a European country like Norway.

10 years on, and in preparation for a new roadmap initiative that would account for embodied carbon reductions, there is a need for further scrutiny and more detailed guidance will need to be imposed to ensure that embodied carbon data reported by pipeline manufacturers is accurate and representative of their true supply chain. The fight against Climate Change cannot be won with questionable embodied carbon data. For more information about the UK concrete pipeline industry’s carbon footprinting, EPD and sustainability work, please visit:
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Aqua-SlotTM offers a durable, effective drainage solution for the M6

In their quest to find a suitable drainage solution, which can be rapidly installed at their M6 J13-J15 upgrade scheme, Kier Highways worked closely with Stanton Bonna to develop an offsite linear drainage system called the Stanton Bonna Aqua-Slot TM Drain.

Kier Highways was faced with a challenge in their M6 J13-16 upgrade. Their traditional manufacturing method for surface water slot drains used in-situ concrete slip-forming, a process which can be considerably time-consuming, leading to significant delays due to the extended partial highway closure, and vulnerable to weather conditions. In-situ concrete also meant more trades, deliveries, traffic, and workforce on site. Kier Highways wanted a solution that enabled them to have more control over the project’s time and schedule. It was evident to Kier Highways, especially after discussions with Stanton Bonna Business Development Manager, Neil O’Sullivan, that an offsite solution was the way to go.

The discussion with Stanton Bonna led to a decision to replace the in-situ concrete slipform system with an offsite precast concrete system which can be mass produced and rapidly installed for such Motorway upgrade schemes. The M6 project was just a start for such a new system in constructing slot drains in highways.

As the scheme required up to 31km of Aqua-slot TM Drain, it was necessary to get early input from the client, design team and Stanton Bonna, allowing mass production to start far ahead of on site installation. The factory production programme was tightly aligned to the scheme’s requirements. As the Aqua-Slot TM Drain units are manufactured in Stanton Bonna’s factory in Derbyshire, the central UK location was ideal for the direct, just in time delivery to site. The units were then rapidly installed on site at a speed of around 200m per day, with almost no delays due weather conditions.

Kier Highways’ project director, Richard French, was very pleased with the offsite winning formula employed with Aqua-Slot. He noted that the “…Outputs are better than expected and we are very pleased with the product. Any reduction in trades and numbers in what is a very constrained environment has to be seen as a positive”.

Find out more about the Award winning Aqua-slot, from Stanton Bonna, here:
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Marshalls CPM offsite manhole system offers best sustainable option for housing development in Leighton Buzzard

Working in a 95 hectare Redrow housing development in Leighton Buzzard, civil engineering contractors Fox (Ownby) Ltd were faced with the challenge of supplying a low carbon, high quality drainage system for the development. Marshall CPM’s precast-based Perfect Manhole offered the ideal solution.

Once completed, Redrow’s Leestone Park housing development at Chamberlin Barn, Leighton Buzzard, will consist of 950 homes, shops, a local centre and a new lower school. The main project’s civil engineering & earthworks contractor, Fox (Owmby), were faced with the challenge of reducing the overall embodied carbon impacts of their operations. The Market Rason based contractor contacted Marshalls CPM to enquire about carbon-efficient solutions for the drainage systems.

Marshalls CPM proposed an offsite solution using their precast based “Perfect Manhole”, employing a range of 1200mm, 1500mm and 1800mm manhole systems. The choice was based on a study carried out a few years ago by international consultants Carbon Clear on different manhole systems which found that a precast sealed manhole system can have a 30% and 45% lower carbon footprint than plastic and traditional box-based concrete manholes (respectively). The use of the Perfect Manhole sealed system eliminates the need for concrete surrounds to improve watertightness and resistance to flotation. Carbon Clear also found that concrete pipes can lower the carbon emissions of construction by 35% on average compared to equivalent plastic pipes. A more recent study found that savings may actually double over the whole-life of a project as, unlike plastic manholes, precast based manholes are designed and manufactured to meet a 100+ years Design Life. Another advantage of precast-based systems is the ease and speed with which it can be installed.

James Stewart from Fox (Owmby) Ltd noted “this is the first time we have used Marshalls CPM sealed systems. We cannot believe how easy it is, with all the benefits that it offers we will continue to install the Perfect Manhole solution”.

More information on Marshalls CPM “Perfect Manhole” can be found here:
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