Croy Engineering provided GPS/GIS/Surveying Services for the data collection effort for the entire stormwater structure network within the City Limits of Smyrna. The City of Smyrna encompasses approximately 15.1 square miles and includes 10,400+/- storm structures (not counting 190+/- detention ponds). The inventory data was determined to be “survey grade” quality and subsequently this data will be used for modeling at the completion of the inventory process. 

This effort included the inventory of all major storm structures within public rights-of-way and the adjacent structures onto private properties (where permissible).  Typical driveway ditch culverts were not included in this work, unless it was a part of the main storm network system. About 3.5% of the total storm structures were buried/inaccessible, at which point a general location list was provided for the City to investigate and either “raise to grade” or provide access to obtain the inventory information.

Croy’s used a grid system to methodically work from north to south from the northerly city limits boundary to the southerly city limits boundary. This entire project was directed by a GIS/Survey Project Manager who coordinated field efforts with the Survey Field Manager and downloaded the final processed data into a GIS database. The GIS software used was ESRI ArcMap 10 and an FTP site was established for the transfer of data for the City’s GIS specialist. The GIS file was separated into storm structure types, pipe connectivity and inventory information required for modeling the network system. 

The field data was compiled using “Survey Grade” Trimble 5800 RTK GPS units, utilizing a Virtual Reference Station (VRS) broadcast system and TGO (Trimble Geomatics Office) software. If conditions were not conducive for GPS, conventional survey means were used. One to two surveys crews were assigned for the duration of the project, which also included the identification of creeks, ponds, and wet-weather ditches; monthly Inspection Reports; monthly GIS updates; and quality checks, as needed. Final grid-plots produced using AutoCAD were provided to the client in order to keep them apprised of progress.