A major project to rehabilitate sewer and stormwater reticulation systems at Park Station in Johannesburg has received a top award from the Southern African Society for Trenchless Technology (SASTT).

The project was awarded the 2015 Joop van Wamelen Award of Excellence at SASTT’s 25^th AGM at Johannesburg Water’s Zandfontein Depot earlier this year.

“This project was an important showcase of our total solutions package, from initial investigation to preliminary design report, construction drawings and overseeing the entire construction process,” explains Meghan Brinkley, Professional Engineer, Management and Advisory Services, SMEC South Africa. SMEC South Africa completed the project in partnership with contractor Trenchless Technologies.

“I would like to thank the entire team, both from Trenchless Technologies and SMEC South Africa, for their efforts in ensuring the successful completion of this project, under extremely difficult site conditions,” Brinkley comments.

 

Going trenchless

Horizontal Directional Drilling (HDD) was used for the refurbishment of the Park Station sewer network. This is a steerable trenchless method of installing underground pipes whenever trenching or excavating is not practical.

Conventional trenching techniques were not an option as the line that had to be replaced ran underneath the railway lines at Park Station. HDD has a minimal impact on the surrounding area, making it ideal for a range of applications and soil conditions.

HDD was used to drill a new 160 mm Ø HDPE pipeline diagonally underneath the train tracks at Park Station in order to connect existing manholes with the new main-line manhole constructed on PF11 (Platform) and PF12. A new 250 mm Ø HDPE line was also drilled from the new manhole on PF11 to PF12 to the municipal connection manhole under Harrison Avenue Bridge.

 

Prioritising maintenance

In order to prioritise effective maintenance, the new reticulation network was structured for easy accessibility. SMEC South Africa’s investigation called for repairs on existing sewer pipes inside sewer ducts. In addition, inspection eyes had to be installed and joints adequately sealed.

All sewerage flowing from the aboveground shopping outlets and toilets between PF1 to PF10 is now collected by four 110 mm diameter uPVC pipelines, supported by a service tray for easy access and visible inspection.

It is critical that these pipelines run parallel to the train tracks and do not cross the train power lines at any point. Four 110 mm Ø uPVC pipelines drop vertically and offload sewerage into platform manholes, as well as a new manhole constructed on PF9 to PF10.

“Going forward, continued maintenance will ensure effective operation of the sewer network for years to come,” concludes Brinkley.