Pacific Water Conference 2020

Brown and Caldwell (BC) recently completed a field inspection and condition assessment of portions of stormwater system in the Central Maui neighborhoods of Wai‘ehu, Kahului and Wailuku for the Department of Public Works. The County recently experienced failure of several stormwater pipelines in the project area. The combination of intense storms and deterioration of aging pipelines resulted in collapsed pipe walls that lead to sinkholes. The failures resulted in real property damages to County roadways and privately-owned property. The County’s intent was to complete a condition assessment of the storm drainage system in known problem areas and prioritize repair or replacement projects for their upcoming CIP budget.
Initially, the scope of work for this project envisioned to include cleaning and CCTV inspection of all structures and pipelines in the project area. However, due to budgetary constraints, BC developed an alternative approach that includes screening level inspection of nearly 100% of the project's 425 structures and nearly 60,000 feet (>12 miles) of pipeline by using a pole-mounted zooming camera system. The benefits of using the pole-mounted zooming camera system are multiple. The pole-mounted zooming camera system does not require pipes be pre-cleaned for inspection. The system is lightweight and portable allowing operators to walk to structures that are off-road or within private property. Typically operated by a 2-person inspection crew, the system is run from ground surface, so permit required confined-space entry is not necessary.
In addition, BC completed light detection and ranging (LiDAR) sensors scanning system on select assets within the project. Current technology stitches the collected data into one, single point cloud that can be viewed and analyzed for asset geometry, configuration and condition. The data collected will fill in and validate the County’s GIS database, track changes of structure dimensions and condition over time, and estimate the size of defects or other undesirable conditions within the manhole.
Results from the inspection were used to identify and prioritize assets in poor condition that need immediate cleaning and re-inspection and/or structural repair. The remaining stormwater system assets, based on their operational and structural rating, were prioritized for point repair, rehabilitation, future planned cleaning, screening level inspection or detailed CCTV inspection.