Sanitary Sewer Manhole Inspections Study and Rehabilitation Recommendations

The City of Columbia currently operates and maintains approximately 16,000 manholes.  The City has a long-term commitment to improving and maintaining the City’s sanitary sewer infrastructure.  Current actions taken by the city have reduced the number of emergency calls however are limited to improvements and maintenance of sanitary sewer pipes.  During CCTV inspections, many manholes have been identified in fair or poor condition, thus recognizing the need to complete a comprehensive manhole inspecting project.   TREKK Design Group was contracted by the City to conduct a manhole inspection project at a rate of 2,000 manholes per year over a 10 year period.  The scope of services consists of providing manhole inspection, evaluation, reports, and final manhole rehabilitation construction plans. 

As part of TREKK’s responsibilities, the following tasks have been completed:

3,000 Manhole Inspections – Exceeded the 2,000 manholes per year by 1,000 manholes in the first year.

Customized Inspection Forms – The standard TREKK manhole inspection form was modified to match the City’s preferred data collection format.

Wet Weather Inspections – All inspections have been conducted during high ground water conditions.  Additional field crews were mobilized to complete maximum inspections during times of excessive wet weather conditions.

ArcGIS/Hydra Compatible Database – A customized Microsoft Access database was designed that is compatible with the City’s current ArcGIS program and the City’s current hydraulic model, Hydra. 

Rehabilitation Demonstrations – TREKK sponsored several manhole rehabilitation product demonstrations for the City.  A number of manholes identified for rehabilitation during inspection, were evaluated and various rehabilitation products were demonstrated and evaluated over time to guarantee the best final product recommendation for the manholes in the City of Columbia.

Manhole Rehabilitation Construction Plan – Delivered complete manhole rehabilitation construction plan package to the City.  This package included a detailed manhole rehabilitation schedule, scanned inspection forms, inspection photos, database of collected data, bid documents, and construction specifications.