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    CHUG STILL

    Isle of Wight, United Kingdom

    PBF Drainage Service Ltd

    Picote Flexi-Sliplining System

    Trenchless Repair
    Location:
    Isle of Wight, UK
    Date:

    April 2023

    Time frame:
    2 days
    Pipe:

    Discharge pipe with root ingress, cracks, fractures and infiltration issues

    Contractor:

    PBF Drainage Service Ltd

    Work:

    Picote Flexi-Sliplining System

    Pipe:

    DN150 (4"), 2 lengths totalling 180m

    Background

    PBF Drainage Services Ltd were contacted by Metro Mechanical Services Ltd
    to carry out drainage repairs to a foul water discharge to sea pipe on the Isle of Wight. 
    The works involved full length lining of a DN150 VC pipe that ran from the private treatment works to the outfall in the sea. Total length of the works was 180m in two separate lengths.

    location map

    A Challenging Location!

    Access from the treatment works was difficult due to multiple large treatment tanks and various pipes and electrical conduits. Access to the middle chamber was via a small overgrown track, through a heavily wooded and boggy area with little to no access for equipment. The last chamber before the outfall was located just above the high-tide mark on the beech located on hard standing and with plenty of space.

    location image

    The Pipe

    The discharge pipe had substantial amounts of root ingress, multiple infiltration locations and various cracks and fractures along its length. The system itself had high flows during wet weather and the outfall pipe was backfilling during high tide and so limited working windows were available.
    in pipe images

    The Problems

    The team looked into various methods of repair including full length CIPP using either UV light cure, hot cure using either hot water or steam, LED light curing methods, spray coating and also ambient curing methods. Due to the limited working times between high- and low-tide the working window was approx. 8 hours between the beach chamber and intermediate chamber becoming surcharged, CIPP was not a viable option.

    Lining upstream was considered but due to the amount of infiltration this was not feasible and the added costs of stopping the infiltration first were prohibitive and increased the risks involved. Spray lining methods were discounted due to the difficulty of getting the pipe dry before coating.

    IN HOST

    The Picote Solution

    Traditional slip-lining requires access pits, large winching or pushing equipment, expensive pipe welding equipment, and additional labour and plant on site.

    PBF Drainage Services Ltd have worked closely with S1E Ltd and Picote Solutions for many years on projects ranging from Picote Brush Coating™️, Picote Miller machinery and Picote tooling for removing failed liners, hardened deposits, and concrete. PBF Drainage have a large array of equipment to carry out all these tasks.

    After discussing the works with Terry Ingleby from S1E Ltd, the consensus was to use a new product from Picote Solutions. Terry had been trained on the new Picote Flexi-Sliplining system and after discussing this method in detail the decision was made to use this product. 
    This would be the first use of the Picote Flexi-Sliplining method in the UK, and another first for PBF Drainage. 

    IOW CASE STUDY COVER SMALL

    The Picote Flexi-Sliplining Method

    The Picote Flexi-Sliplining method does not require any excavation. It uses a small portable welding rig, lightweight materials and the pipe is very flexible so that all works could be carried out from the existing chambers and ground space on site. 
    The final pipe sizes and pipe wall thicknesses were taken into consideration, and it was determined with the help of S1E Ltd that the OD of 140mm and ID of 125mm would not be an issue due to the increased flow characteristics of the finished materials. 
    All the relevant information was gathered and submitted to Metro Mechanical who in turn discussed options and risks with the end client.
    Training was carried out at the Picote Training Centre in Sandhurst as arranged by S1E. This was only a short training session due to the previous experience with sliplining,

    The works would require some initial root cutting, CCTV surveying and high-pressure jetting all carried out by Metro Mechanical's in-house team the week prior to the actual repair works. The final surveys were provided to PBF Drainage to ensure everything was satisfactory. 

    Due to the layout of the downstream chamber a small amount of benching was removed to allow for the access and the guide frame to be placed inside the chamber. This was due to the direction change in the chamber.

    TRIM

    The winch rope was pulled through the entire length of pipe to the downstream chamber.

    Everything was ready for installation on the first day on site, which took approx. 4 hours to complete.

    The materials for the repair works were delivered to site and then transferred onto a smaller vehicle due to the limited access on site. This was possible due to the lightweight design of the 6m lengths of DN140 pipe. Each length could be lifted and transported very easily by a single person. 32 lengths of pipe were transferred to the works location, where the pipe welding would take place. 

    Picote flexi sliplining

    Progress!

    The long access road to the beach with a large open grassed area was ideal for carrying out all the initial preparatory works. The welding rig was set up and powered by a small generator, rollers were placed at various locations to aid the process of pulling the pipe as it grew. The small welding equipment with pipe clamps, joining frame and cutting tool were all lightweight and extremely easy to use. Both lengths of pipe were welded in a single shift with each weld taking approx. 10 minutes to complete. In total the welding of both full lengths took approx. 6 hours in total. 


    The final day on site consisted of setting up the pipe frame which guided the pipe into the 
    downstream chamber, where each section would be pulled in from. The first upstream length would be pulled through the intermediate chamber until it arrived at the treatment works. 


    The pulling head was secured into the start of the pipe and the winch rope attached. The pipe was guided over the frame and through the pipe guide in the base of the chamber. A small battery-powered capstan winch was used to pull the pipe into place. The pulling process was carried out at a rate of approx. 8m per minute. Once the pipe was on its way there were no other additional works 
    required as the pipe fed itself over the rollers and into the host pipe. 


    Once the front of the pipe reached the upstream chamber the pipe was allowed to rest for 45 minutes allowing any tension in the pipe to naturally reduce. The pipe was then cut to length allowing a small amount to be used to bench the new pipe into the channel of the host pipe and chamber. The second downstream section was pulled into place the same as the first using the upstream chamber as the winching point. All the pipes were secured into the existing chambers, the benching repaired. All works were completed within 2 days on site.

    ERECT
    If you would like to book a call with one of our team to discuss you own project, please use the contact form below and we will be in touch with you as soon as possible. 
    Contact Picote Request Form
    LIFT LENGTH
    Lightweight and easy-to-handle lengths of pipe reduce transport costs and waste.
    GRASS
    Minimal disruption to the local environment.
    RIG TRIM-1
    Simple and fast onsite assembly is key to reduce shipping issues and material waste.
    ATTACH END
    The end of the triple-walled pipe is secured ready for pulling.
    PROGRESS
    The pipe starts to pull in with the powerful winch, the pipe flexibility eliminates the need for digging.
    Picote Flexi sliplining assembly in the field
    Assembled on site 
    Picote Flexi-Sliplining case study

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