Due to time constraints, rehabilitation of sewers needed to be performed concurrently with an urban environmental upgrading project involving decorative paving and resurfacing works. Non-disruptive trenchless techniques were identified as the only viable rehabilitation solution for these challenging site conditions.

Acidic effluent had severely corroded the concrete sewer lines. The most severe deterioration was detected at the sides of the larger line, where high flow velocities created 60 mm (2.5 inch) wide sills on either side above the low flow level. It was estimated that sections of sewer would collapse within 10 years.

SPR^®EX / Expanda^® and SPR^®PE / Ribline^® technologies both provided complete no-dig pipe rehabilitation solutions, with liners able to be installed through existing access chambers.

Compact installation equipment made rapid daily mobilization and demobilization times possible, which was essential given both lines are located beneath heavily trafficked areas.

SEKISUI Rib Loc Australia’s unique RIB LOC^® spirally wound structural liners met hydraulic capacity requirements and maintained their circular shape and quality during installation despite the sharp edges of the sills.

This was the first project in Africa to use spiral wound technology. Despite the difficult challenges encountered, a genuine no-dig solution was able to successfully rehabilitate the two sewer pipelines without any disruptions to traffic or the public.

In recognition of the success of this project, Trenchless Technologies cc was awarded the International Society for Trenchless Technology (ISTT) 2012 Annual Project Award.