GIS PROJECT PROFILE

GIS Conversion of the Town of Wilton Sewer and Water Data
 

Early in 2005, C.T. Male’s GIS Group contracted with the Town of Wilton Sewer and Water Authority to set up GIS technology for the Town of Wilton to manage and map water and sewer system data. The purpose was to streamline and facilitate water and sewer system engineering, capital improvement project planning, maintenance, repairs and day-to-day operations. 

To quote from Opflow, the American Water Works Association Bulletin
(Vol. 30, No. 10, October 2004, p. 20):

“Up-to-date geographic information for water and sewer lines is crucial for organizing and implementing a water or wastewater utility’s distribution system maintenance activities and creating and updating hydraulic modeling. For example, operations personnel must track how many feet of pipe to flush, how many gate valves to exercise and how many fire hydrants to repaint within certain time frames. Statistical information is also required for governmental regulatory agency surveys and questionnaires.”

Project Scope

1. Digitizing of sewer and water system maps, including the addition of attributes such as pipe type, length, material, slope, etc. into GIS file format. 
2. Addition of “hot-linked” image or other document files to the water and sewer files.
3. Field verification of selected water and sewer system features, by means of GPS (Global Positioning System) surveying.
4. Addition of townwide base map information to the GIS project.
5. Setup of GIS project – including the acquisition and purchase of software – to utilize the above information.
6. Training in how to use the GIS software and data.
7. Purchase and setup of GPS receiver.
8. Linkage of GPS output to GIS.
9. Training in the use of GPS and GPS/GIS data conversion.

Project Procedure

1. Digitizing

   Hard-copy maps were scanned so the originals could be returned to the Town of Wilton within a week.  Digitizing was accomplished using GIS street centerlines and digital tax parcels as guides, and the state aerial photography from the spring of 2001 as the base map. This “heads-up” digitizing technique of locating each element according to the surrounding geography is both accurate and time efficient.  In the few cases where the geographic positioning was in question or the infrastructure was somewhat complex, we georeferenced the scanned image to the base map using our GIS software, and then “traced” the features on the screen. An example of the georeferenced scan is shown as Figure 1. 

   

   Figure 1: Town of Wilton hard copy as-built map that has been scanned and georeferenced to the correct geographic location. This raster file is used to "trace" infrastructure elements into GIS vector files. Attributes are added from the map annotation.

   Attributes were added to the database based on the annotation found on the original maps, and an example of data stored with each geographic feature can be seen in Figure 2 below.

   

   Figure 2: Identify button shows the details for any geographic feature. Information must be added as attributes to the GIS database, using map or field derived data.

   We created the data layers as ESRI shapefiles, then imported these into an ESRI personal geodatabase. This geodatabase format will allow future additions of geodatabase “relationships” such as those required for flow analysis, while the shapefile format allowed the town to use the GIS layers for mapping, data analysis, GIS queries and all other functions that relied on shapefiles at that time. 

   The “hot-link” referred to here is the addition of image or other (for example, Word Document) files linked to the GIS point features. This allows the user to “point and click” using the hot-link button, which results in the image or document popping up in the GIS window.  We found that this task was less useful than the other applications, and not too much time was spent on it.
    

2. GPS Field Verification

   We researched the GPS Receiver market, with the help of our Survey Group. A competitive quote from Waypoint was accepted. C.T. Male’s GIS/GPS technician, Pat Rooney, helped the Town create a Data Dictionary using Trimble Pathfinder Office – one that was consistent with the database design established for infrastructure features. Mr. Rooney subsequently accompanied Mike Mooney in the field to show him how to collect the data. GPS training was thus accomplished while locating and field verifying selected water and sewer features. Once the training was complete, Mr. Mooney was able to do this task on his own.

   While the downloading of field-collected data into an existing GIS database is addressed, in detail, in the Trimble manuals and in the GPS Training, Pat Rooney worked through the specific data for the Town of Wilton.  Pat created a short, data-specific user’s guide, complete with detailed screen shots.
    

3. GIS Project – Setup and Data Addition

   Publicly available data was added to the Town’s GIS project. This included street centerlines, tax parcels, federal and state designated wetlands, state aerial photography, USGS quad sheets, elevation contours (same accuracy level as the USGS map) and a variety of other information available through the NYS GIS Clearinghouse and the data sharing cooperative associated with the state GIS Clearinghouse.
    
   We created several mosaics from the aerial photography in order to make digital orthophotography files less unwieldy. We made sure that appropriate USGS maps without “collars,” projected to the coordinate system to match other GIS data, were available in the GIS.

   We set up the Town of Wilton GIS Project on the C.T. Male server in our office before we delivered it to the Town. Having an exact copy here allowed us to give continuing telephone tech help after the project installation.
    

4. Training – GIS and GPS
   
   Our GIS Technician, Chris Secor, is particularly talented in teaching novice GIS users how to get maximum value from their GIS. Chris taught Mike Mooney how to use the project – including which buttons and tools do what. Chris planned the training sessions around the questions relating to this specific project. In addition, he made a short Users’ Guide, or “cheat sheet” to leave beside the Town of Wilton GIS computer, and he is still involved in telephone tech help on occasion. As detailed above, the GPS training was accomplished while actually collecting usable data. 

Results

As is the case with most of our GIS projects, once the work is underway and the client begins to use the application for day-to-day work flow, the original scope may shift and/or expand. For the Town of Wilton, all of the available maps and CAD data incorporated were into the project, rather than just the 50 or so maps suggested in the original scope. We are still on call for tech help – by phone, and on a few occasions, with visits to the Town Water and Sewer Department. This project has been an unmitigated success, according to all parties concerned. Infrastructure maps (as shown in Figure 3 below) at almost any scale can be created in minutes, once the template has been set up.

Figure 3:  Map created from Town of Wilton 11X17 layout template. Scale and Legend are automatically updated to show what is on each particular map.