Knowledge of the ‘as-is’ structural integrity and hydraulic performance of buried sanitary conveyance systems is crucial and provides guidance to municipalities on (i) prioritizing repair and replacement projects, (ii) avoiding costly and disruptive emergency repairs and (iii) importantly, minimizing public and environmental impacts. The current work reports the development and implementation of a systematic condition assessment program for (i) a 2.3 km long 560 mm forcemain and (ii) 5 km long 600 mm forcemain. Both forcemains are welded steel pipelines, with 12 mm coal tar epoxy and/or 25 mm insulation, overlaid with yellow jacket. The latter forcemain has a section buried under the Yukon River.

For the condition assessment of these critical forcemains, we employed its in-house Condition Assessment Systematic Approach, developed from combining concepts from the fields of (i) forensic engineering, (ii) data integration/fusion processes and (iii) statistics. The proposed approach considers the sewers’ parameters (e.g., MOPs, wastewater chemistry, age, burial depth, material, etc.), expected current and future level of service, operational requirements, constraints, and history (e.g., surcharge, repairs), the remaining structural/hydraulic capacity, biogenic corrosion potential, external corrosion vulnerability assessment and the projected rate of deterioration, to design applicable renewal and/or asset management interventions. Operational and other site constraints largely informed the choice of inspection technologies and our 5-stage project delivery approach which includes (1) Desktop Assessment, (2) Field Work Planning, (3a) In-line Leak & Gas Pocket Detection, (3b) ‘As-is’ Structural Integrity Data Collection (including soil corrosivity analysis), (4) As-built Design Evaluation, Integrity Assessment & Remaining Service Life Evaluation, and (5) Recommendations & Implementation Plan.