Trenchless Sewer Rehabilitation

Project Highlights

The City of White Rock retained Kerr Wood Leidal to develop and implement a city-wide sanitary sewer rehabilitation program designed to reduce inflow and infiltration (I&I).

Program’s Components and Goal

The program’s goal is to meet the GVRD Liquid Waste Management Plan’s objectives for I&I reduction.  This comprehensive program includes flow monitoring, field inspection, system modelling, I&I characterization, rehabilitation and post-rehabilitation assessment.

System Assessment and Repairs

The 8-hectare rehabilitation area consists of benched and sloped development, containing some 7,000 metres of AC, PVC, and VT pipe ranging in size from 150 to 375 millimetres in diameter.  KWL assessed the condition and performance of the sewer system via CCTV inspection of the sewers and flow monitoring.  It then identified specific pipes requiring repair and the appropriate repair techniques.  These included relining (segmental and manhole-to-manhole), grouting (mainline joint and service interface), and open trench point repairs.

The rehabilitation work consisted of the following:

• relining of 460 metres of pipe, plus 6 segmental point repairs
• testing and/or grouting of 5,100 metres of pipe, including 250 service interfaces
• excavated point repairs at 23 locations.

Contract Administration

Contracts for the repair work were awarded based on rehabilitation technique.  KWL recommended that follow-up pressure testing be awarded to a different contractor to ensure independent verification that the work was completed as specified.

Next Phase

KWL will continue the flow monitoring program to assess the effectiveness of the rehabilitation work.  The results will also be used to identify and prioritize future rehabilitation projects, ensuring that the City of White Rock progresses towards compliance with the GVRD’s Liquid Waste Management Plan in a well-planned and efficient manner.