Newsletter: Summer 2015

Posted by & filed under eNewsletters & eBlasts.

Welcome to the Summer 2015 issue of Pipelines

The popularity of precast manhole base systems is rising as users appreciate the many benefits they offer. However, there are still many installers, developers, specifiers and clients missing out.

If you are interested in reducing risk on site, cutting installation time and costs, improving quality and eliminating leakage and you are not using CPSA members’ precast manhole base systems, it’s time you took a closer look…

Stuart Crisp, Director, CPSA

Concrete manhole system, packed with many benefits that will satisfy designers, contractors and operators alike

Traditionally, manhole construction has required the base to be formed in-situ where building of the channel, connections and benching occurs in the trench, often in confined spaces that can present a safety hazard for operatives frequently encountering wet and unpleasant conditions.

The process can take around 40 hours per manhole to complete and is not always successful, particularly in terms of water-tightness, where egress of waste water can lead to contaminated groundwater and where ingress can contribute to overloaded sewer networks plus increased energy usage, carbon emissions and running costs at treatment works and pumping stations.

These issues can be avoided by using the new circular precast concrete manhole base systems available from all CPSA members. They comprise a circular precast concrete base unit, complete with channel and benching with predetermined / bespoke combinations of inlet(s) and outlet and new chamber rings with watertight flexible joints and no lifting holes, thereby removing points of possible leakage.

Base units and chamber rings are made with thicker, stronger walls. The robust design means that the requirement for a concrete surround is eliminated in most cases, considerably reducing the total volume of concrete required and resulting in up to 43% lower(*) embodied carbon for the installation. The excavation is backfilled sooner and there is less need for men to work in confined spaces. This reduces time spent in the excavation, further improving site safety and reducing installation time and costs.

(*)CPSA Manhole Systems Comparison Report

The manhole system the drainage industry has been waiting for

Precast Concrete Manhole Installation

Installation of the whole system is speedy and efficient. Take a look at CPSA members’ demonstration videos

CPMs Perfect Manhole Installation

Fast, Safe and Efficient Installation of FP McCann’s Easi Manhole Unit

Stanton Bonna The Perfect Manhole System

Enviromental Advantages

Less concrete is used, there is less waste and less excavated material disposed to landfill. An estimated UK annual saving of over 22,000 tonnes of CO2e could be achieved if all traditional manhole components manufactured by members of CPSA changed to the new precast base system.

All systems are manufactured under factory conditions by third party certified companies to ISO 9001 quality management system. Products are Kitemarked to BS EN 1917:2002 and BS 5911-3 and tested under laboratory conditions.

The precast manhole revolution: safer, higher quality, faster, cheaper – are you missing out?

Posted by & filed under Pipes & Manholes.

Traditionally, manhole construction has required the base to be formed in-situ where building of the channel, connections and benching occurs in the trench, often in confined spaces that can present a safety hazard for operatives frequently encountering wet and unpleasant conditions.

The process can take around 40 hours per manhole to complete and is not always successful, particularly in terms of water-tightness, where egress of waste water can lead to contaminated groundwater and where ingress can contribute to overloaded sewer networks plus increased energy usage, carbon emissions and running costs at treatment works and pumping stations.

These issues can be avoided by using the new circular precast concrete manhole base systems, which are available from all CPSA members. They comprise a circular precast concrete base unit, complete with channel and benching with predetermined/bespoke combinations of inlet(s) and outlet and new chamber rings with watertight flexible joints and no lifting holes, thereby removing points of possible leakage.

Base units and chamber rings are made with thicker, stronger walls. The robust design means that the requirement for a concrete surround is eliminated in most cases, considerably reducing the total volume of concrete required and resulting in up to 43% lower(*) embodied carbon for the installation. The excavation is backfilled sooner and there is less need for men to work in confined spaces. This reduces time spent in the excavation, further improving site safety and reducing installation time and costs

Benefits of the Precast Manhole
• Improved safety on site
• Reduced construction time; c50% (min 20%)
• Decreased installation cost; c30% (min 15%)
• Superior quality; factory made in a controlled environment
• Watertight; reduced leakage = reduced energy consumption, operational carbon emissions and running costs at treatment works and pumping stations
• Typically, no concrete backfill/surround required
• Reduced embodied carbon; up to 43% per manhole

(*) CPSA Manhole Systems Comparison Report

The Concrete Pipe Lifter: Safer, Easier, Faster, Cheaper

Posted by & filed under Construction, Health & Safety, Innovation.

The Concrete Pipe Lifter is a cost effective, simple-to-use system, which has been introduced to the UK by CPSA. It is a chance to improve safety, reduce costs and increase productivity.
The Concrete Pipe Lifter is a collaboration across all members of the CPSA who are working to reduce risks and to increase efficiency during deliveries, offloading and installation of sewer pipes in open cut trenches.

Concrete Pipe Lifters connect to an excavator via a quick hitch attachment and have no motorized parts making it easier to maintain. The lifting arm is inserted horizontally into the barrel of the pipe and raised to make contact with the internal crown of the pipe. The clamp arm will press down onto the top of the pipe at the socket end and hold it in position.

The concrete pipe is lifted without using slings or chains and without the need for an operative working at height on the bed of a lorry during offloading. The Pipe Lifter can be used to install the pipe with no-one in the trench and to push the pipe home to ensure formation of the correct joint gap.. The pipe may also be tilted up to 30 degrees from horizontal and manoeuvred between struts on trench support systems.

The Concrete Pipe Lifter is suitable for standard UK specification BS EN1916 concrete pipes from DN 300 to DN 1200 and the Type 2 lifter is designed for larger pipes DN1350 to DN2000.
Concrete Pipe Lifters make handling and installing concrete pipes safer, faster, easier and cheaper.

For more information and videos on The Concrete Pipe Lifter visit us today.

Newsletter: Spring 2015

Posted by & filed under eNewsletters & eBlasts.

Welcome to the Spring 2015 issue of Pipelines

In this issue we are focusing on the Concrete Pipe Lifter. For many, this incredible, award-winning piece of equipment may be an overlooked gem.

There is nothing more important than the safety of construction site operatives during the offloading and installation of pipelines. Often, the introduction of safer working practices can lead to lower productivity and higher costs. In contrast, the Concrete Pipe Lifter is a rare chance to greatly reduce risk on site with the combined opportunity to significantly increase productivity and reduce costs.

The sad news of the death of workman in Swindon during the installation of cast iron sewer pipes is a stark reminder of the real risks that workers are exposed to and the importance of proper risk assessments and safe working methods.

The Concrete Pipe Lifter is a major step towards safer, faster, cheaper pipeline installation. It must not be ignored.

Stuart Crisp, Director, CPSA

Lay concrete pipes quicker with less cost and less hassle

Traditional methods for lifting and offloading concrete pipes include the use of slings or chains connected to integrally cast lifting hooks built into the pipe. These methods require an operative on the back of a vehicle during offloading to connect the slings / chains to the pipe and in the trench during laying to disconnect the lifting tackle from the installed pipe. It is reported that more than 75% of major fall-from-vehicle incidents occur during loading and unloading activities. The HSE estimated in 2004/05 that the human and economic cost of reported fall from-vehicle incidents was over £36.5 million.

The Concrete Pipe Lifter is a simple-to-use, inexpensive system introduced to the UK by CPSA. It is a collaboration across all members of the Association who are actively driving to improve site safety and increase efficiency during the delivery, offloading and installation of sewer pipes in open cut trenches.

The Concrete Pipe Lifter is connected to an excavator via a quick hitch attachment and uses no motorised parts making it easy to maintain. The lifting arm is inserted horizontally into the barrel of the pipe and raised to make contact with the internal crown of the pipe. The clamp arm will press down onto the top of the pipe at the socket end and hold it in position. The pipe may now be lifted and transferred to a suitable storage location or placed into the prepared trench and jointed following the application of an approved joint lubricant to the pipe spigot, if required. The pipe may be tilted up to 30 degrees from horizontal and manoeuvred between struts on trench support systems. It can also be used to push the pipe home to ensure formation of the correct joint gap.

Find out how you can buy or rent the Pipe Lifter from CPSA’s supply partners here.

Manual Handling

Lighter weight products made from other materials may initially appear easier to use and some suppliers have suggested that these items can be used without the need for mechanical lifting equipment. In fact, according to Health & Safety Executive guidance on weight limitations for manual handling, many lighter weight products are in excess of the upper limit for safe lifting. In many cases, this means that HSE guidelines and Safety Best Practice are not being followed and the use of “light weight” as a marketing tool could lead to lack of appropriate risk assessment and safety management on site. CPSA’s Information sheet on Manual Handling offers information on this.

The Impact of Totex on SuDS

Posted by & filed under SuDS, Sustainability.

Peter Martin, Technical Director at Black & Veatch recently produced a blog on the Susdrain website  ‘How might SuDS look in the water industry’s (brave) new world’.  I would like to pick up on Peter’s point 3 on Totex in his blog.

Peter has stated how water company costs are now measured on a total expenditure basis, also known as ‘Totex’ rather than the previous capital expenditure (capex) and operating expenditure (opex) basis.

He expresses the importance of cost distribution within water companies and how it looks like water companies will now be able to partake with others in jointly funding projects and refocus their business on delivery of outcomes that directly benefit customers in place of project outputs biased towards asset creation.

Whilst these changes in principle make sense, they represent a profound change in business orientation that cannot be successfully implemented overnight on the back of a simple change of policy. It will require a culture change across all areas of the business and a suitably planned and co-ordinated change management programme.  Currently, some water companies seem to be paying lip service to totex when in reality it is suspected that they continue to drive down capital expenditure using existing procurement models and supplier terms of contract as a basis to demonstrate reducing total expenditure.

A big challenge for asset owners in demonstrating authentic totex savings is the need to make reliable forecasts of the future performance of assets and the interventions required in order to extend the service life of the asset.  This will be particularly challenging if accepting higher capex costs in order to deliver lower (opex and) totex costs.  The design team must have confidence that the asset will perform as predicted and there needs to be adequate operational data and experience relating to the asset dating back, in some cases, many decades.

By way of an example, the UK’s sewerage infrastructure is up to 160 years old and we know that at the current level of investment in replacement and renovation that a sewer constructed today will need to last, on average, 800 years.

Is it likely that the funding for maintenance and the replacement of proprietary SuDS assets will be evidently different to that for sewers?  Our knowledge of the sewerage market should help to inform us of the likely outcome with SuDS and the need to design systems that are durable.  Totex cannot be determined reliably without proper consideration of the long term performance of assets in addition to capital cost efficiencies.

Concrete is inherently strong and robust and is well placed to offer capex savings through reduced cost bedding designs and safer, faster installation using the concrete pipe lifter whilst simultaneously providing opex benefits as a result of its proven long service life.

For more information on Sustainable Urban Drainage Systems or SuDs, follow the link or give us a call today!

 

Overspecification of pipe bedding – the implications

Posted by & filed under Costs, Design.

CPSA_FB_POSTBedding is an essential component in every “open cut” pipeline installation. Its primary function is to transfer loads between the pipe and the surrounding soil.  However, the design of the bedding system can have a significant impact on the cost of an installation and also on the environmental impact of the project as a whole.    We believe that overspecification of bedding systems contributes unnecessary cost to pipeline installations.

There are numerous pipe bedding Classes such as Class S, B, F and N with different construction details using varying amounts of imported granular material and different load distribution characteristics.  Bedding Classes B, F and N require significantly less granular material than Class S which requires a pipe to be completely surrounded.

The actual bedding Class required can differ depending on the type of drainage pipe used.  British Standard 9295: Guide to the Structural Design of Buried Pipelines provides examples of common pipe materials, their strength and their classification.   Pipes will generally be considered either “rigid”, “semi-rigid” or “flexible”.

Flexible pipes, such as thermoplastics, derive up to 95% of their structural strength from the embedment either side of the pipeline.  Generally this means that flexible pipes have to be fully surrounded by the correct granular material, sufficiently compacted, as defined under Class S.

This design of embedment will require considerable quantities of aggregate to be extracted and transported to site while the material excavated from the trench will often need to be removed and disposed of in landfill. This process has both a financial cost and an impact on carbon emissions.

By contrast in rigid pipes, such as precast concrete, up to 80+% of the design strength is inherent in the pipe itself, which in many cases allows users to choose from a range of bedding solutions requiring less granular embedment.

An acceptable design for a concrete pipeline in many instances is bedding Class B, which entails only surrounding the lower half of the pipe with bedding material – often termed 180o granular bedding.

Given the pressure on contractors to minimise cost, installation time and environmental impact, choosing the most appropriate bedding design is clearly in the best interests of the project. However, in many instances there is a lack of understanding of pipe embedment design.  This can lead to a conservative approach being adopted and the unnecessary overspecification of a bedding solution.

The materials savings achieved from using bedding Classes B, F and N as opposed to Class S can be considerable.  To help designers and installers assess the scale of savings, the CPSA has developed a web-based Structural Design Calculator to help in the selection of appropriate bedding Classes for buried pipelines.  www.concretepipes.co.uk/page/structural-design

When bedding Classes have been selected, the costs of alternative designs can be compared using the CPSA’s online Material Cost Calculator www.concretepipes.co.uk/calculators/material-cost

 

 

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Hydraulic efficiency of different pipe materials

Posted by & filed under Design.

Reliable estimation of the hydraulic performance of pipeline systems is one of the most important aspects of drainage design. There are many determining factors and many debates arguing the case for different pipe materials and configurations. To achieve hydraulic analysis accuracy, it is imperative that the designer has the correct design information and makes appropriate assumptions regarding the behaviour of the pipeline system over its operating lifetime.

Here are just a few of the key hydraulic drainage design criteria that need to be considered:-

Size, shape and profile.

The nominal size of the conduit assumed for design purposes may vary from the actual dimensions of the manufactured product.  Check that the nominal diameter of the section of pipeline under consideration is actually available at the size being considered in the design.  Be careful not to specify a pipe nominal diameter that is greater than the available pipe size. For example, according to Hydraulics Research Design Tables based on Colebrook-White equation for pipes flowing full and using a hydraulic roughness Ks = 0.6mm for storm water sewers, a DN300 pipe laid at a gradient of 1:60 will have a reduction in capacity from 140 l/s to 136 l/s if the internal diameter is 291mm, i.e 3% below the 300mm nominal internal diameter. For larger diameter pipes the shortfall may become more significant, particularly if compounded with other capacity-reducing factors. Check out the manufacturing tolerances of different pipe materials and product designs. You may be surprised at what you find.

This may seem obvious, but it is usually overlooked. The hydraulic design of circular cross section pipeline systems assumes that the pipe maintains its circular cross section shape over its service lifetime. The ovalisation of flexible pipes (where the vertical diameter reduces compared with the horizontal diameter) will reduce the hydraulic efficiency of the pipeline. For example, in storm water sewers the majority of rainfall events will lead to flows within pipes at less than 50% proportional depth. An ovalised pipe will lead to lower average pipeline velocities at a specific flow rate compared to the original circular profile. This may lead to greater risk of sedimentation and accumulation of detritus within the pipeline and may be of particular relevance in areas where (a) extended dry periods exist, (b) high intensity rainfall at or close to the design value, where self-cleansing velocities are achieved, is encountered on an infrequent basis or (c) where the sediment entering the system is significant. The fact that rigid pipes such as concrete do not deform or lose their shape during their service life also means that the hydraulic performance of the cross section used in the original hydraulic design is preserved without compromise.  Use your design software to determine the reduction in hydraulic performance of ovalised flexible plastic pipes at 5% (which is allowable in many client authorities) and add this effect to any variance in nominal diameter.

It is also important that pipelines maintain their longitudinal straightness to ensure optimum hydraulic efficiency. They should be constructed with a proper understanding of the ground conditions into which they will be buried, the loads applied to them and provided with sufficient support to ensure that their profile does not waver with localized dips and high points throughout their length. If pipelines deviate out of alignment, additional head losses can result within the system. Flexible pipes have low resistance to bending and can be vulnerable to ground movement over their length.

Hydraulic roughness

The hydraulic capacity of a pipeline depends on the gravitational energy lost due to friction as water flows over the surface of the wall of the pipe.  It is therefore unsurprising that much attention is focused on the smoothness of the parent material of the pipe that makes up the interior pipe wall. The smoother the wall, the greater the hydraulic capacity of the pipeline system, assuming

(a) Any comparison between different pipe materials takes into account other factors such as variance against nominal diameter, consistency of cross sectional shape over the operating life of the pipeline and longitudinal profile.

(b) That the walls of the pipe remain unaffected by the build up of slime or accumulation of sediment that would change the effective hydraulic roughness of the pipe surface.

Wastewater pipelines are required to perform over a very long period, typically in excess of 100 years.  Over its service life, the pipeline will only behave in an “as new” state for a short period, even assuming regular and frequent maintenance.  For this reason, it can be misleading to base hydraulic designs on the “as new” condition using the hydraulic roughness value for the pipe material.  It would be far wiser to use a practical hydraulic roughness value based on a degree of sliming and siltation, such as those used in Sewers for Adoption (Ks=1.5mm for foul sewers; Ks=0.6mm for storm water sewers) for all pipe materials.

Additionally, many flexible sewer pipes incorporate a “ribbed” structure to the outer wall of the pipe. As a consequence of the manufacturing process, the outer ribbed surface of the pipe will often be reflected to some degree on the inner wall of the pipe resulting in a corrugated internal surface. Accordingly, the hydraulic roughness of structured wall (ribbed) plastic pipes can be greater than that of smooth bore pipes, leading to reduced capacity of the pipeline system.

When using concrete pipes, the risks associated with size tolerance, consistency of cross sectional shape, longitudinal profile and corrugated internal bore may be avoided. Clients, designers and installers should understand these basic hydraulic design factors so that they can more accurately determine the long term hydraulic performance of the pipeline system.

For more information on Hydraulic Design please visit the CPSA site.

Some pros and cons of the Government’s new SuDS legislation

Posted by & filed under SuDS, Sustainability.

In November I wrote about industry concerns with the Government’s proposed approach to implementing sustainable drainage systems. In December the Government took the path of least resistance and announced that sustainable drainage systems (SuDS) are to be introduced to England and Wales through existing planning policy.

In the long-awaited announcement, Communities Secretary Eric Pickles explained that local authorities will have responsibility to ensure that new developments of 10 or more homes and all major new commercial and mixed use developments include SuDS. [http://www.parliament.uk/business/publications/written-questions-answers-statements/written-statement/Commons/2014-12-18/HCWS161/]

Under a SuDS solution surface water run-off is managed using landscaping and underground storage solutions. SuDS is about dealing with rain where it falls, which is in contrast to conventional drainage solutions which are designed to carry run-off from a development to an outfall as quickly as possible. The new SuDS arrangements will take effect on 6th April 2015, and planning policy will be strengthened accordingly.

While the new approach may avoid delays to the planning process, it is not as far reaching and clear as the original 2012 proposal, which was based on implementation through SuDS Approval Bodies. The withdrawal of Schedule 3 of the Flood and Water Management Act 2010 and the changes to existing planning policy mean SuDS will not be a legal requirement alongside the planning process. Instead it has been diluted to a planning consideration; as such it will be down to each individual planning authority to lay down their requirements for SuDS.

Under these new arrangements local planning authorities should now consult the lead local flood authority on the management of surface water to satisfy themselves that a development’s proposed SuDS solution is appropriate under the approval process. The lead local flood authority should be able to assess the risk of surface water flooding across planning boundaries to help reduce the likelihood of flooding.

This arrangement makes sense and should help overcome concerns about the capacity and technical expertise of local planning authorities to deal with drainage issues. A proposal to make the lead local flood authority a statutory consultee is the subject of a new consultation, which closes on 29 January. https://www.gov.uk/government/consultations/planning-application-process-statutory-consultee-arrangements.

That said, this is a piecemeal approach, with individual local authorities consulting with individual lead local flood authorities, which could result in inconsistencies nationally that may lead to disputes occurring between developers and local authorities.

The ongoing maintenance of SuDS is a concern despite the SuDS approval process requiring local authorities to ensure developers have ‘economically proportionate’ arrangements in place for maintenance over the lifetime of a development. The issue of SuDS ownership is crucial; for example, maintenance could be carried out by the local authority, water company or by a private contractor, which means there will be less certainty over who actually has responsibility for a scheme’s maintenance which could leave property owners saddled with high maintenance costs.

SuDS will only apply to medium and large scale developments, those of 10 or more homes and major commercial and mixed-use developments. The Government says this threshold is to avoid “excessive burdens on business”. However, developers could exploit this loophole with partial development of plots in stages of up to nine homes at a time. Furthermore, there is no reference to the size of the properties or square area of the total development site.

Similarly, if there are a lot of small developments in an area the cumulative effect of run-off from all of these may not be addressed. However, the 10 home-trigger is a practical starting point for the new rules, provided the threshold is reduced over time.

Eric Pickles announcement also gives developers and planners a SuDS opt-out clause: SuDS do not have to be provided if they can be “demonstrated to be inappropriate”. As such, this could allow planners to choose not to insist on SuDS when the costs associated with them are deemed to affect the viability of a development. So, if an authority is set on developing an area, it can do so regardless of the consequences on drainage.

It is also worth noting that with this announcement the government has chosen to adopt a far narrower definition of SuDS than the one generally accepted as best practice. Water quantity and flood mitigation are referred to at length, but water quality, amenity and biodiversity are given far less prominence.

The CPSA’s members welcome the introduction of SuDS as part of a range of drainage solutions to help protect people and property from the risk of flooding. As manufacturers of dependable SuDS components, including flood control, attenuation and underground storage systems, CPSA members are able to work with designers and installers to provide precast concrete SuDS solutions that offer excellent whole life value. For more information on Sustainable Urban Drainage Systems follow the link.

CPSA to support free 2015 CPD RoadSeminar programme

Posted by & filed under Training.

CPSA will attend six Construction CPD RoadSeminar events throughout 2015.

The RoadSeminar Tour itself has been running successfully for over ten years. RoadSeminar events are free to attend and will give you up to 6 CPD hours. It provides a platform for professionals to meet and learn about industry changes and developments.

CPSA will be presenting the well-received seminar “Surface Water Management using proprietary precast concrete SuDS systems”. This seminar provides an introduction to the legal framework driving changes in the design and construction of surface water management systems in the UK . It also highlights the basic principles associated with sustainable drainage systems (SuDS) and their ownership, operation and maintenance. In this context, proprietary precast concrete SuDS components and systems will be identified and their specific uses examined.

RoadSeminars attended by CPSA: 

  • Manchester 15th April
  • Leeds 16th April
  • Edinburgh 14th May
  • London 2nd July
  • Nottingham 7th October
  • London 12th November

Find out more on our website or visit the Construction CPD Website for more information about the 2015 RoadSeminar Tour.

Newsletter: Winter 2014

Posted by & filed under eNewsletters & eBlasts.

Welcome to the Winter 2014 edition of Pipelines, your eNewsletter from CPSA.

In the Spring 2013 edition of Pipelines we discussed the introduction of a new National Standard for sustainable drainage (SuDS). It was expected to come into force in April 2014. Well, that didn’t happen – and we are still waiting! In the intervening period, the bank of knowledge and reference material has grown, through excellent sources such as Susdrain. Some important changes have taken place, not least the launch of a new consultation on SuDS by DEFRA and DCLG. See below for more information on the proposed changes and what it may mean for SuDS.

Also in this issue, a reminder of the considerations for air testing newly constructed sewer pipelines, including a video providing helpful, practical guidance.

We have also included a link to the full CPSA video library. There’s a wealth of useful and interesting information in there.

If you are up to speed with social media, CPSA is well served on numerous platforms and we also have a blog, so why not get connected?

And don’t forget, we have a number of free CPD seminars to keep your professional development up to date, independently accredited by CIWEM and Construction CPD Certification Service. These are available to book at your office or other suitable location.

Stuart Crisp, Director, Concrete Pipeline Systems Association

We’re delighted to announce we are a Susdrain Supporter

CPSA has joined an impressive cross-sector group of organisations dedicated to supporting the www.susdrain.org initiative, further demonstrating growing industry support for widespread delivery of Sustainable Drainage Systems (SuDS).

Over the next two years, it is anticipated that there will be a significant increase and improvement in the delivery of SuDS, with positive change driven by new guidance and the potential implementation of National Standards for Sustainable Drainage.

Susdrain will help support improvements in SuDS delivery through a range of initiatives including new resources, summaries of the latest guidance, case studies and a series of topical SuDS events.

CPSA is one of 29 organisations including Defra, the Environment Agency and other key industry players involved in the project from September 2014.

Since its launch in 2012, Susdrain has provided a valuable range of resources for those involved in delivering SuDS. Susdrain will continue to support drainage and highways engineers, planners, urban designers, landscape architects, land or housing developers, suppliers, flood risk managers, biodiversity / environment managers and the general public to increase knowledge and confidence in the delivery of SuDS.

New SuDS consultation – for better or worse?

On 12 September 2014, Defra and DCLG launched a joint consultation document, which set out a possible approach for implementing sustainable drainage systems and mechanisms for ensuring their long term maintenance. There are some important differences between the proposed new approach and the previous direction that the industry was heading.

The proposed new approach may avoid delays to the planning process, compared with the SuDS Approval Body (SAB) approach, but SuDS and drainage expertise is still required. This is not generally found in the town/district/borough councils and therefore may have to be sub-contracted. The anticipated general consensus to the consultation is that the proposed approach is the path of least resistance and therefore could see SuDS delivered more quickly. There is however concern for the quality that will be delivered.

Read the full blog here

Fires in sewers, combustible pipes and pipeline integrity – is it worth the risk?

On 28th September 2014 fire-fighters were called to a fire at a building site at Cargo Fleet Lane, Middlesbrough after reports that 20 large plastic sewerage pipes had deliberately been set alight. The blaze resulted in the streets surrounding the site having to be cordoned off after the area was blanketed in a cloud of noxious black smoke.

Similar incidents have been reported in America. One such example is where children playing in a 42″ diameter storm culvert built a fire to keep warm; this then set light to the HDPE pipe which resulted in fire damage spreading for over 800′ along its length.

It is not just arson that pipe users need to be aware of, brush fires, vandalism, fuel spills and industrial accidents all have the potential to initiate fires in pipelines. As a result, designers, installers and asset owners should consider combustibility and the risk of fire when selecting pipe materials, gully tops and drain gratings.

Plastic burns. If these pipelines had been constructed from a non-combustible material, such as precast concrete, it is unlikely that either of these fires would have occurred, simply because concrete does not burn.

Where a fire has occurred in a drainage pipeline a secondary consequence of a fire is the impact of the fire on the pipe itself. Fires in concrete pipes generally do not affect their structural strength, flow capacity or corrosion and abrasion resistance, whereas plastic pipes can melt and collapse.

All of which raises the question: is the use of drainage pipe materials other than concrete really worth the risk? Concrete has inherent strength and a proven service life of over 100 years … and it is non-combustible.

Read the full blog here

Leak-Tightness testing in pipelines

All newly-laid drainage pipes, including manholes, should be tested for leak-tightness prior to backfilling.

There are two basic tests; the air test and the water test. An air test involves using inflated stoppers at both ends of a section of the pipeline under test. Pressure is then introduced into the section of pipeline and after a stabilisation period the pressure is checked. In the event of a single or continued air test failure, recourse to a water test is allowed and the result of the water test alone shall be decisive.

A water test involves creating a head of water in the pipeline which is examined for tell-tales signs of leakage. Following a period of settlement and acclimatisation, the level of water in the header tank is monitored for a specified period and the loss of water measured and checked. It is not unknown for a pipeline that has failed an air test to pass a water test.

For more information about leak-tightness testing refer to BS EN 1610:1998 – Construction and testing of drains and sewers.

We have a video on how to air test concrete pipelines on our YouTube channel. Please click here to view the video