AK2

Wimbledon, UK

Picote Flexi-Sliplining
Copse Hill Park, London

Public Sewer Services (PSS)

Location:

Wimbledon, London, UK

Date:

September 2023

Work:

Picote Flexi-Sliplining to renovate deformed pipe 

Contractor:

Public Sewer Services (PSS)

Pipe:

375mm deformed plastic pipe

Special thanks to:

Trenchless Works (taken from November 2023 edition)

Introduction

Works were recently carried out on a Public Sewer Services site in Copse Hill Park, Wimbledon, southwest London, UK. A poorly installed 375 mm diameter twin wall plastic pipe was significantly deformed.

The Details

The site comprised mature woodland, meadow land, a park area, playing fields, a nature reserve, swale and footpaths. The area also exhibited delicate soil conditions as well as a fragile ecosystem. The acidic soil type attracted unique plants and wildlife. Residents from the affluent surrounding area were also concerned about any works that were required as there are very few green spaces accessible to them. With limited site access and the stakeholder restriction on any excavation, options for a purely trenchless method were sought. After considering various options, discussions with rehabilitation systems provider Picote Solutions identified a solution using its new Flexi-Sliplining system

The Solution

The Flexi-Sliplining system utilises German manufactured Flexirohr pipe with tooling designed by Picote. The pipe has a corrugated outer skin so there is minimal use of oil in its production, resulting in a much-reduced overall weight and therefore the installation is also free of potential toxic waste. The corrugated pipe is DIBt certified and has been utilised in several European countries as well as South America. The major advantage of the system is that no excavation is needed in an installation between two manholes (in sizes >800 mm diameter). This offers a huge advantage compared with traditional PE sliplining as no lead-in trench is required. The structure of the pipe allows it to negotiate smaller bends in the host pipe, should they exist. The FlexiSliplining system can be used for host pipes between DN100 to DN300.

picote flexi sliplining installation

Installation is achieved by connecting the liner pipe to a winch cable which pulls it through the host pipe at a rate of up to 8 m (26 ft) per minute. Once installed the ends of the pipe are fixed in the manholes at either end. The system has also pull-resistant couplings for any pipe connections. One innovative addition to the Flexi-Sliplining system is the new pipe welding system. Picote R&D has developed unique tools for this welding process, including: a new welding rig, welding inserts, pipe cutters, pulling heads and welding balls. Also, the equipment used for pulling in the pipe has been significantly redesigned. All of these new tools make the installing process easier, faster and more efficient. The tools are simple, light-weight and have good ergonomics. The Hurner welding rig used is specially adapted for Flexi-Sliplining with a barcoding system, so that users can determine the temperature and time for each weld. 

Given these advantages, the Flexi-Sliplining systems it was chosen for the Wimbledon project. PSS mobilised its experienced specialist pipe bursting team with bursting equipment to work in conjunction with the Picote team and equipment to install a new replacement pipe. Utilising a Picote welding rig, Picote Battery winch, winch plate and guide poles, Picote pipe guide, Picote Flexi-pipe cutter, Hurner welding rig, and a Picote Lower guide, three surface water drain pipes of 375 mm i.d. were rehabilitated. Two pipes were 42 m long, and the third was 72 m long. Each was lined with 270 mm o.d. Flexi-Sliplining pipe which was supplied in in 6 m long sticks. In this instance the pipe for the lining work was supplied by RSM. In a display of customer service, when a tool broke late on the first afternoon, RSM had a replacement tool on site with the installation crew by 7 a.m. the following morning. According to Dawn Greig, Senior Director with Picote: “This was really was exceptional service and allowed the site crew to continue the works uninterrupted. The Picote Technical Team stayed on site with PSS to complete the job. Whilst there were several unexpected challenges on the project, the combined team used their expertise to overcome the difficulties to succeed in a job which was originally considered to be potentially unviable.” The start date for the works was 18 September, with the final installation being completed and the site cleared by 20 September, a total of just 3 days on site. Production, once the liner pipes were welded to the required lengths and moved into the towing position, was impressive with each of the 42 m pulls taking approximately 25 minutes to complete and the 72 m pull took just 40 minutes.

Picote flexi sliplining in Wimbledon

PSS, utilising a design consultant, selected a specialist flowable mortar with appropriate strength to grout the annulus between the Picote pipe and the host pipe to ensure long term structural stability. For PSS, Steve Tierney, Delivery Manager stated: “This has been a challenging job from the very outset including the pipe layout, site conditions and the number of stakeholders involved. We worked hard to source a suitable ‘best for task’ method and worked closely with Picote to complete an innovative No-Dig project using new technology.” Commenting on the project Dawn Greig, Senior Director with Picote said: “Public Sewer Services was one of Picote’s first customers when the company started in the UK back in 2012. We were therefore delighted that the company chose to utilise our Flexi-Sliplining system for this challenging project, which was not only one of our first in the UK but also the largest diameter here to date. We truly appreciate their continued support. We would like to thank their excellent team for this opportunity and hope to work with them on future trenchless projects.” 

Picote Flexi-Sliplining Wimbledon case study
Picote Flexi-Sliplining in Wimbledon
Picote Flexi-Sliplining Wimbledon case study
Picote Flexi-Sliplining in Wimbledon
Picote Flexi-Sliplining Wimbledon case study
Picote Flexi-Sliplining installation in Wimbledon
Picote Flexi Sliplining Wimbledon case study
Picote Flexi-Sliplining in Wimbledon