GIS for Sewer System

GIS Assessment, Sewer Mapping, Sewer Data Management, and Inventory Assessment

Weston & Sampson was retained to develop a Geographic Information System (GIS) for the City of Lebanon’s sewer system. Weston & Sampson evaluated the city’s existing resources for use in a comprehensive, scalable GIS focused on asset management and modeling. Our evaluation included a detailed investigation and close coordination with local users and decision-makers regarding their proposed interaction with and use of the GIS.

The city’s sewer manholes were surveyed using a Real Time Kinematic Global Positioning System (RTK-GPS) to obtain highly accurate horizontal and vertical positions. This process ensures that a consistent elevation dataset exists across the entire system. Accurate and consistent elevation data is vital to modeling. More than 1,600 manholes were surveyed throughout the city. This data was incorporated into the city’s GIS.

The city’s existing records were used as a source of pipe connectivity and attributes. The sewer pipe and manhole attributes were populated with all information available on the record plans. A geometric network was created to enable proper connectivity of sewer structures in the GIS and to allow for advanced network tracing routines. All sewer structures were assigned unique asset IDs based on subarea and flow direction. The scanned record drawings were linked to the GIS.

The city’s existing manhole inspection, television inspection, and rehabilitation project data were linked to the GIS to show the history of maintenance and repairs.

Once complete, the sewer GIS was used to develop a plan for performing additional sewer assessment work, including smoke testing, television inspections, and manhole inspections. The GIS will be used by the city for capital improvement planning and to track maintenance and repair operations.


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