Condition Assessment and Rehabilitation of a 150 year old Brick Sewer Inventory in Victoria

Abstract

This paper outlines an overview of a condition assessment and rehabilitation program for the City of Victoria’s 150-year-old brick sewer infrastructure. AECOM has provided engineering services for inspection and renewal of storm drain assets since initiation of this program in 2009. The inventory is comprised of nearly 10 km of brick sewer (originally combined sewers, now strictly stormwater) with largely non-circular cross sections including both egg and arch shape cross sections ranging in sizes from 914 mm x 610 mm to 2100 mm x 2855 mm (HxW). The physical condition of the inventory ranges from sewers in excellent condition (Structural Performance Grade (SPG) of 1, 100+ years later) to some in advanced states of deterioration (SPG 5). To date, approximately ½ of the system has been rehabilitated with fully structural liners. The program has employed risk-based condition assessment techniques and the deployment of a suite of conventional and advanced condition assessment tools. The rehabilitation approach has used trenchless technologies including CIPP and slip-lined segmental GRP. The program has spanned the evolution of non-circular liner design, including WRc Type 1 and 2 designs modified for arch shaped pipe, up to the current ASCE MOP 145 approach. The paper provides an overview of the City of Victoria’s brick drain inventory, a summary of the drivers of degradation of brick sewers, the approach to condition assessment, rehabilitation methods used, liner design approach and procurement considerations.