Using handheld field computers and GPS units to acquire data during I/I investigations for sanitary sewer systems

“Do more with less” is the motto in the wastewater utility industry as new technologies continually emerge for use by managers and maintenance professionals of the nation's sewer systems. Still, only a relative few organizations have used handheld field computers and global positioning system (GPS) units to acquire data during inflow and infiltration (I/I) investigations of sanitary sewer systems. This streamlined data-collection process results in higher worker productivity and enhanced quality of information, which in turn can be used to populate a geographic information system (GIS) for use by planning and maintenance managers. The total process integrates pentop computers for data collection, Web cameras for a direct link to the database, and GPS receivers for real-time location during data collection. Once the data is collected (or even as it is being collected), it can be integrated into a GIS and used to identify defect locations and magnitude as well as recommend rehabilitation methods.These technologies were used for projects in Concord, North Carolina, and Charleston, South Carolina, and are currently being used for the Metropolitan St. Louis Sewer District in unincorporated St. Louis County (more than 96 municipalities). The St. Louis project includes approximately 4,500 miles of sewer pipe, with the data being collected from such field tests as smoke testing, dye-flood testing, dye tracing, and manhole inspections. Collected field data will be used to determine any necessary additional tests and to make recommendations for rehabilitating the defects.This paper summarizes why a utility should consider a technology-based process for data collection and sewer assessment, and highlights two case studies where this approach was used successfully.Electronic data collection has several benefits and challenges, including: BenefitsReduced field time/costs. Data can be collected four times faster than with traditional methods.Reduced office time/costs. Data can be collected to be directly integrated into a GIS.Increased quality control. Data collectors are prompted for important information in the field, thus reducing the incidence of missing or inaccurate data. Also, the standardized format of the collection process reduces subjective interpretation of findings.Enhanced photo-capturing capabilities. Digital cameras are wired to a computer so photos can link directly to specific defect data.Increased flexibility. Once electronic data has been collected, it can be reconfigured into other formats (hydraulic models, Web page displays, or computerized maintenance management (CMMS) programs).Increased, immediate location accuracy. The geographic location can be recorded automatically with GPS.Reduced storage-space needs. A tremendous volume of data can be handled with minimal physical storage space.ChallengesSpecialized field data collection equipment is required. This equipment is more costly than the traditional paper and pencil and requires ongoing maintenance.The equipment requires field personnel to be familiar with computer technology and electronic data handling.The data must be backed up nightly and extreme care must be taken not to accidentally erase the data.Multiple field computers need individual identification systems so data is not overwritten.The project must be very organized – pre-planning is required