Graeme Monteith,Tunnelling Engineering Manager at Barhale Construction, has been appointed chairman of the Pipe Jacking Association and Jim Kirby, anAssociate at consulting engineer Donaldson Associates, vice-chairman.
Graeme, a graduate of Camborne School of Mines, has over 30 years experience in tunnelling, pipe jacking and associated civil engineering, much of this within the water sector. Jim Kirby has 24 years contracting and consultancy experience, specialising in tunnelling and pipe jacking,shafts and pipelines.
Commenting on hisappointment Graeme Monteith said: “ The PJA has been active in a number of key areas to include education and research, technical innovation and industry standards. We plan to continue and grow these activities and to raise the awareness of pipe jacking as one of the primary methods for installing drainage and other utilities in urban areas with the minimum of disruption, and significantly reduced carbon outputs”.
A thesis covering the disaggregation of soil during slurry pipe jacking has been published by the Geotechnical Engineering Research Group at City University, London. The dissertation has been submitted for a Doctor of Philosophy degree by Neil Philips who was supported throughout the project by funding from the Pipe Jacking Association.
The thesis can be downloaded from the research section of the Pipe Jacking Association website : here
The abstract summarising the research appears below:
Pipe jacking is an environmentally friendly technique for the installation of services and utilities, which leads to minimum disturbance during installation. It is an important construction method for urban environments where disruption to transport is expensive. The need to tunnel through varying geologies requiring support during tunnelling has led to the increased use of slurry tunnel boring machines. The slurry is used to stabilise the tunnel face and transport the excavated spoil to the surface.
The research detailed in this dissertation assesses the magnitude of soil disaggregation during the excavation and pumping of the arisings within the slurry to the separation plant. The two main objectives were to create a mixing test that would allow the disaggregation of the soil to be predicted prior to specification of the separation plant and to link the results of this test to typical soil properties. In addressing the second objective efforts have also been made to characterise the
different mechanisms of disaggregation observed in the mixing tests. The typical soil testing methods used to classify the soil samples were; Atterberg limits, particle size distributions, unconfined compressive strength, mineralogy (XRD) and chemical analysis (XRF).
A mixing test has been designed using a Hobart planetary mixer to classify the amount of soil cuttings that disaggregate during mixing with a slurry fluid. This test was found to produce repeatable results using Speswhite Kaolin samples and then used to assess the differences in disaggregation rates of London Clay, Upper Mottled Beds and Fleetwood Silts. In total 71 mixing tests were completed during the development of the test and the classifying of the soils. The test involved mixing distilled water with 10 clay cuttings for varying times. The resulting solid particles
were then sized through a series of sieves and sedimentation tests carried out to produce a particle size distribution of the resulting soil.
The mixing tests showed the Upper Mottled Beds to have the highest rate of disaggregation, with the Fleetwood Silts displaying the least. This has been attributed to the level of cementing within the soil and the microstructure of the clay and silt sized particles.
The liquidity index and initial soil strength were not found to be important factors in the predicting the rate of disaggregation of a particular soil type, but were significant for some soils. The Fleetwood Silts had the lowest unconfined compressive strengths but also produced the least amount of disaggregated soil. The soil macrofabric, although not quantified, also appeared to have an effect on the rate of disaggregation of a particular soil. An increase in discontinuities within the sample produced more cuttings larger than 4.75 mm but a lower amount of 63 ?m sized fraction disaggregated.
In addition to the mixing tests carried out using water, a series of tests were completed using a polymer based slurry, HydroCut CF. This showed mixed results; The polymer prevented any clay or silt sized particles from passing through the 63 ?m sieve. However, there was no overall reduction in disaggregation and a significant increase in the time it took to sieve the slurry.
The Pipe Jacking Association currently has funds available and wishes to offer a number of bursaries to universities that are currently, or propose undertaking, MSc or other postgraduate research projects in subjects which can be considered to support pipe jacking, tunnelling or complementary activities. The proposed bursaries are £2,000 each although these could be increased in appropriate circumstances. Applications should be sent to the Pipe Jacking Association secretary, firstname.lastname@example.org , with a brief description of the research proposal, the manner in which the funds will be spent, and the relevance of the research to the industry.
The Pipe Jacking Association is a trade association with a successful history of research collaboration with Oxford and Cambridge Universities, as well as Leeds and Newcastle and our current project is nearing completion at City University. In addition, the Pipe Jacking Association has been instrumental in establishing and supporting tunnelling technology courses at Bridgwater Technical College and Kingston University. It has also disseminated results of its research to both industry and designers through conferences, seminars, lectures, papers, and Pipe Jacking Association publications which are freely available. Full details of our past research activities can be viewed on our website: www.pipejacking.org .
Applications should generally be made by mid-September for the following academic year. In the event of a Pipe Jacking Association bursary being awarded the Pipe Jacking Association will delegate a suitably experienced representative from a member company to attend research meetings, as appropriate, and support the project as required.
Digging up urban roads creates massive carbon emissions compared to non-disruptive tunnelling solution. Now, savings of up to 75% in carbon emissions have been demonstrated by a web-based application (www.pipejackingco2calculator.com) which compares open-cut utility installation with non-disruptive solutions, such as pipejacking or microtunnelling, for the installation of sewers and other utilities in urban highways. The comparison tool has been developed on behalf of the Pipe Jacking Association by TRL (Transport Research Laboratory), the international consultancy that provides research, consultancy, testing and certification for all aspects of transport.
The Pipe Jacking Association represents the major contractors and suppliers in the pipejacking and microtunnelling industry. Pipe jacking, generally referred to in the smaller diameters as microtunnelling, is a non-disruptive technique for installing underground pipelines, ducts and culverts. Powerful hydraulic jacks are used to push specially designed pipes through the ground behind a shield at the same time as excavation is taking place.
The 75% saving in carbon emissions, (>370 tonnes), was achieved by comparing the installation of 500 metres of 600mm pipeline, 6 metres deep, using non-disruptive techniques with open-cut construction. Additionally, the construction period for the trenchless installation was projected to be less than half that of the open-cut construction1. At shallower depths carbon savings are typically in the range of 50-60%.
The free and easy to use carbon dioxide emissions calculator, that in seconds can produce indications of comparative emissions, has been verified by WRc plc, an independent research-based consultancy that provides sustainable solutions for the protection, enhancement and maintenance of the natural environment.
TRL’s project manager, Matthew Wayman commented: “The findings should encourage water and other utilities to consider pipejacking and other non-disruptive trenchless techniques when appraising new utility installations.” The application enables the user to identify more carbon (and energy) efficient options, and can therefore assist them to meet reduction targets established as a result of applying carbon regulations or other voluntary guidance, including the Department of Energy & Climate Change’s CRC Energy Efficiency Scheme (formerly Carbon Reduction Commitment)2, or other independently initiated key performance indicators.
Data for the calculator has been drawn from a number of authoritative sources that include the University of Bath’s Inventory of Carbon and Energy for construction materials, the Concrete Pipeline Systems Association, and outputs from the Department for Transport’s QUADRO program (Queues and Delays at Roadworks) developed by TRL. Reports can readily be produced that not only provide comparative emissions data for open-cut and non-disruptive options, they also detail data sources and assumptions utilised in the calculations.
Further options are available to input detailed additional data as a project progresses.
Notes to Editors
1 Roadworks related congestion is estimated to cost the UK economy around £4 billion a year (DfT press release 26 January 2012: New powers for councils to control roadworks: see note re link below). Successive governments and London mayors have expressed concern and attempted to control the disruption caused by utility companies and in early 2012 the Government announced enhancements to the New Roads and Street Works Act enabling local authorities to charge utility companies up to £2,500 per day for digging up busy roads at peak times (lane rental). Apart from carbon savings and the disruption costs, open-cut construction followed by re-instatement is estimated to reduce highway life by up to 30% representing a substantial additional community cost for highway authorities. It is hoped that lane rental charges, together with readily available evidence of carbon savings, and the community cost of highway degradation occasioned by open-cut installation will encourage utilities to adopt non-disruptive trenchless options wherever and whenever possible.
2 CRC is a mandatory scheme aimed at improving energy efficiency and cutting emissions in large public and private sector organisations which are responsible for around 10% of the UK’s emissions and features a range of reputational, behavioural and financial drivers. The Environmental Key Performance Indicators (KPIs) are an initiative by Defra to help businesses demonstrate their corporate sustainability credentials, in particular across a range of environmental indicators that include water and waste.