Slide Welcome to the Southern African Society for Trenchless Technology

The Southern African Society for Trenchless Technology was founded to help inform the public, as well as any interested parties, on the workings and benefits Trenchless Technologies bring to our ever-expanding communities and the role it plays in the development of our country.

What is trenchless technology?

Trenchless technology is a type of subsurface construction work that requires few trenches or no continuous trenches. It is a rapidly growing sector of the construction and civil engineering industry. It can be defined as “a family of methods, materials, and equipment capable of being used for the installation of new or replacement or rehabilitation of existing underground infrastructure with minimal disruption to surface traffic, business, and other activities.”

SASTT Award of Excellence

Submissions

Orsco - Winner of the 2020 SASTT Award of Excellence

Orsco

The client, Sun City Resort in the Bojanala Region of North West province of SA, used the Lock Down (announced by our {president Cyril Ramaphosa to begin on March 26th 2020,) as the perfect time to conduct routine maintenance to the hotels, casino and water parks. One such project that was tackled was the main water supply pipeline at the Valley of the Waves due to the high level of water loss (1000’s of litres weekly) that was taking place.

 

After an investigation using CCTV Inspection, Pipeline Location, pressure testing and other condition assessments systems, Orsco (Pty) Ltd identified many misplaced joints, broken and jammed butterfly values, numerous pinhole leaks and not pipe material degradation due to age (the pipe being more than 28 years old,). The entire pipeline was found to be in very poor overall condition. After survey results were analysed by our surveying technicians & lining rehabilitation engineer Mr Alaster Goyns recommendations were made and forwarded to Mr Bret Hoppe & Mr Thulani Malinga of Sun City that rehabilitation of the DN500 was necessary.

 

The 500mm diameter supply pipeline runs from the pump room around the edge of the valley of the waves, a total length of 173 meters. Excavating to replace and install a new pipeline would have meant weeks and possibly months of no water supply and the added expenses of the new pipeline, excavation, installation etc.

 

Orsco (Pty) Ltd offered the alternative solutions of the ASOE in-line and Nu Cure Lining technology to the Client, highlighting the fast turnaround time without the need to excavate at crucial access points and how the disruption to the park features would be minimized. Orsco offered the fastest, safest and most environmentally friendly solution available which was a combination of a short length of CIPP and the balance being the ASOE hose. Although this was the first time the latter was to be used in South Africa
and the Client accepted in view of the technical and economic the advantages provided.

 

Rehabilitation Method
The first 36 m section was rehabilitated by Orsco and Nu Cure Laboratories using a triple layered 100% glass epoxy liner – this was because no other technology was viable at the time to accommodate the sharp double 90-degree bends. This was compounded by four different pipe materials in the section before and after the double 90 degree bends namely:

 

  • Rubber coating
  • Old existing CIPP Epoxy
  • Steel pipe
  • Asbestos Cement

 

These sections needed to be cleaned and the substrates prepared.

 

It was decided that the 137 m of pipeline between Pit 1 and 2 would be re-lined with a pull in place ‘lay-flat’ type Asoe liner which is used for pressurised pipelines. Three options were submitted, and the decision-making process was carried out between the Contractor & Client and the proposed solution with terms and requirements for each was agreed upon before implementation.

 

The Challenge:

 

A working combination of CIPP and ASOE through carbon steel, cast iron, rubber lining, previous CIPP, Asbestos cement through two double 90’s and then another 6 bends.
Transported: Water
Host Pipe Diameter: DN500
Host Pipe Material: Carbon Steel, Cast Iron, Polyethylene and Asbestos Cement.
Total Length: CIPP – 36m, ASOE – 137m = Total 173meters
Operating Pressure: 1 bar, test pressure: 1,5 bar
Systems Used: Nu Cure G2 DN 500 liner, polymer epoxy & ASOE PE/PE covered press-flat Pipe-in liner DN 500
Breakdown: The project was broken up into 3 phases, condition assessment, CIPP and Pipe-in Liner.

 

Well done and thank you too:
Ewen Nisker – Nu Cure Laboratories
The entire team from Orsco (Pty) LTD
Deon Pohorille – Nu Flow (Pty) LTD
Alaster Goyns – consulting engineer; PIPES CC
Marco Camarda and his entire team – Trenchless Technologies
Tumelo Yarona with the excavation of the two chambers
Beake Engineering with the design and construction of the two chambers
RPM Plastics with the installation of puddle flanges & pipe fittings
Aaron Homing Ni – Asoe Hose Manufacturing Inc

BODOTEX

BODOTEX

The Kirstenbosch National Botanical Garden is known worldwide for its beauty and location in Cape Town. Kirstenbosch was founded in 1913 as the first botanical garden in the world, its main purpose was to preserve the indigenous flora of South Africa. Movement in and around Kirstenbosch is severely restricted, the gardens are unique and are under the protection of the South African National Biodiversity Institute.

 

During the water crisis in Cape Town’s 2017 to 2019 drought, the main waterline feeding Kirstenbosch Gardens irrigation dam became severely damage. This 410 meter DN200 Asbestos Cement pipeline from a weir on Table Mountain was critical in keeping the Kirstenbosch garden alive. Budget constraints and a fast reaction time became critical factors for the gardens survival which was dependent on the waterline’s rehabilitation.

 

To make matters even more complicated, the rules around any rehabilitation or construction efforts within the garden were designed around minimal disruption to flora and fauna.

 

  1. Any remediation method cannot damage the garden.
  2. Minimal noise and disruption was expected.
  3. The 410 m pipeline had to be rehabilitated in one attempt within a maximum of 1 week.
  4. If machinery was to be employed, it would be for short periods only

 

Flexibility in solution was required for an installation where flora was thickly growing within the installation area but was not to be damaged at all.

 

For 1 year, from June 2018 this project was delayed because of budget constraints and the gardens construction limitations until WBHO Pipelines, Bodotex and Amex|Sanivar joined together in a subsidized project and effort to provide a solution at cost to Kirstenbosch Gardens. In this project, the preservation of Kirstenbosch, the pride of the city
and South Africa was more important than any project profits. This effort from industry leaders provided technology in a time of drought and lack of funding.

 

The pipeline is situated both below and above-ground, only one small trench was dug at the lower end / dam end of the pipeline for liner reconnection and replacement of a valve. The challenges in this project were diverse. Before the project even began, everything from liner transportation, liner placement, amount of staff and machinery employed had to be approved by the gardens.

 

In the field, the liner had to be folded up and taped by hand while it was hand winched down to the reservoir at the exit point. Every part of the liner – from the storage, insertion, winching, reconnecting etc. had to be closely monitored to ensure the gardens were not damaged.

 

The entire installation of 410 meters took place during June 2019 in a timeframe of 12 hours. After careful work, placement and planning, the AMEX|Sanivar , Bodotex and WBHO crews were able to successfully hand winch the entire 410 m of SaniTube® by hand without any permanent damage to the protected areas.

 

The host pipeline, a DN200 Asbestos Cement pipe was reinstated after pressure tests, and the first use of the SaniTube® in South Africa was a resounding success.

 

Please see our video on the attached link which details and documents the installation process and results: https://youtu.be/16mzJ6o3tSw

 

SaniTube specifications:
Pressure rating – 16 Bar
Liner Type – potable water ensuring no contamination of irrigation water to flora and fauna.

 

Before pictures:
Tricky landscape and very difficult working area at the starting / installation point of the pipeline.

 

Irrigation dam at critically low levels due to pipeline damage

CSV Construction

 CSV Construction

Project Scope:

 

The project consisted of the construction of a new low lift sewer pump station, rehabilitation of an existing 1000mm diameter concrete outfall gravity sewer and construction of a new downstream section of new gravity pipeline.

 

Trenchless Scope:

 

  • 488m of DN 991 thermally cured unreinforced CIPP liners with thicknesses of 16 mm
  • Inversion lengths ranging from 61 m to 122 m
  • 24 361 kg resin used

 

Over pumping

 

The Main Contractor set up an over pump system at the existing low lift pump station to bypass the gravity main and to pump the sewer flows 1100m further directly to a downstream pumpstation . A temporary 450mm HDPE was used to convey the flows. The over pumping was critical to the exercise to ensure the initial bulk pipe cleaning would not have to be repeated before the actual installation of the liner was to commence.

 

Cleaning of the host pipe

 

Bulk cleaning was required to enable profiling of the existing pipe and a condition assessment to be undertaken and this came with a few challenges. The use of a bucketing system was decided on to start with the initial cleaning process. Ground water and a couple of unidentified (illegal) connections added to the challenge of cleaning the pipe. Local over pumping stations where used to assist with the unwanted inflow during the cleaning process.

 

Access to the Gravity Line

 

Access to the existing gravity main was also hampered due to the dilapidated state of the manholes on the line. The main contractor had to ensure the necessary modifications were made to the manhole cover slabs and internal rings to enable access for cleaning and to ultimately complete the liner installation.

 

The cleaning process took around 8 weeks and was the most challenging part of the entire project.

 

Design and order of liner

 

After confirmation of the structural design the 6 individual liners where ordered from a leading manufacturer in Europe.

 

Installation

 

Working in a volatile area and with installations happening during the evening was one of additional challenges faced. Each installation had to be properly planned and lasted +-36 hours with a continuous shift system in place.

 

The impregnation team prepared the liner by impregnating it under factory conditions with up to 5 tonnes of catalysed resin and it was then transported to site submerged in ice.
Due to the limited working window before the resin-impregnated liners start to cure meant that once the process started, it could not be interrupted. Teamwork was critical: the
consequence of liners curing prematurely would have severe financial implications, as would the time delays required to ship in a replacement liner.

 

Once liners have been cured and cooled down, test samples were cut and sent to a laboratory for integrity testing, to confirm strength and quality.

What are the Benefits of Trenchless Technology?

Environmentally Friendly

Using specialized equipment underground infrastructure is installed, repaired or replaced with minimal ecological disturbance. Infrastructure can be installed under buildings, under forests, under wetlands and bodies of water.

Minimal Disturbance to Surroundings

No one likes their home, business or morning commute to be affected by construction. The footprint for a trenchless construction zone is smaller and often times done in an existing right of way.

Decreased Rehabilitation Time

Because trenchless construction methods require little digging, the time to rehabilitate the work area to as-found or better condition is decreased.

Saves Time

With decreased disturbance, projects using trenchless methods take less time to complete. Less time means less inconvenience associated with a construction project.

International No-Dig 2022 Helsinki

3 Oct, 2022 – 5 Oct 2022

Messuaukio 1, 00520
Helsinki
Finland
Link to Map (opens in new tab)

NODIG Live 2021

Type: Conference,Exhibition
Venue: East of England Showground
Geographical Area: Europe

Hosted/Endorsed by: UKSTT
Contact: Paul Harwood
Email: paul@westrade.co.uk

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