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Condition Evaluation of Sanitary Sewer Systems with Geographic Information System Integration of Close Circuit Television Data

Carroll Engineering Corporation (CEC) is conducting condition evaluations of sanitary sewer systems using geographic information systems (GIS) by integrating data, television reports and sewer inspection videos directly into GIS. CEC used integrated GIS and sewer televising to complete a three year evaluation of Westtown Township’s sanitary sewer system.  The project goal was to update Westtown’s GIS to improve data accuracy so sewer defects could be mapped using GIS queries.

CEC hired Sewer Specialty Services Company (SSSC), a sewer televising company based in Leicester, New York, as a sub-consultant to provide closed circuit television inspection and evaluation of Westtown’s sewer system. CEC’s GIS Department worked with SSSC to coordinate the work prior to SSSC’s mobilization in the field.  CEC produced base mapping and geodatabases identifying the work areas along with site specific naming conventions for manholes, sewer mains and flow direction.  Each pipe and manhole was assigned a unique identifier that served as a key between data sets developed by CEC and SSSC.

Television inspection was performed using the National Association of Sewer Service Companies (NASSCO) standards as described and adopted in the Pipeline Assessment Certification Program (PACP); the North American Standard for pipeline defect identification and assessment.  The goal of PACP is to provide standardization and consistency of defect assessment throughout the industry.

In addition to television inspection of sewers, CEC field personnel conducted manhole inspections, with reports and photographs also linked to corresponding sewer assets in GIS.

Data obtained in the field is imported directly into the sewer GIS using the unique identifier. This allows inspection results, including videos, photos, and reports to be linked directly to the corresponding sewer asset in GIS; and allows the data to be viewed within GIS mapping software.  In addition to inspection data, CEC used field data to update the original base mapping and geodatabase with lateral stationing, pipe length, size, and material.

With a complete GIS based condition survey of Westtown’s sewer system, CEC began evaluating the condition of the sewer system using PACP codes. Querying PACP codes in GIS allows the generation of maps based on specific defects.  Defect categories were grouped for subsequent queries to produced maps that illustrate areas of the sewer system in most need of attention.  With inspection data linked directly to sewer assets, review of inspection reports and videos can be prioritized for areas of the sewer system in need of repair.  Manhole defects were mapped in the same fashion as sewer defects to identify needed repairs.

The GIS environment allows multiple personnel to simultaneously work with sewer inspection information using GIS viewing applications. The use of GIS to evaluate the condition of Westtown’s sewer system also allows CEC to prepare GIS based maps and plans for sewer repair contracts.  Standard symbology is used to identify types of defects and defect information can be labeled on plans directly from the geodatabase.

CEC continues to build our sewer GIS capabilities. We have added handheld applications for manhole inspections including, global positioning system (GPS) acquisition of manhole locations, and direct linking of photographs taken with smartphones or tablets.  The applications are available to be used by our client’s field personnel to update sewer system data during their regular duties.  Data acquired in the field can be forwarded to CEC to update the sewer GIS.