|
Methods: Since the health department does not generate and maintain base geographic files of the county, the Zanesville/Muskingum County Health Department (ZMCHD) has worked closely with the Muskingum County GIS department to obtain current geographic files to be used in GIS projects. An accurate centerline file with address ranges provides the most use since most health department data sets contain an address. In the past, ZMCHD relied on TIGER road files for most GIS projects. Recently, Muskingum County was one of the first counties in Ohio to take advantage of the Location Based Response System (LBRS) initiative. LBRS is a state effort to share the county’s cost (determined by the road miles and addressable structures in the county) of obtaining accurate, field verified, road centerline data with address ranges. Additionally, every residence’s road access (i.e. driveway) was also collected so the data includes a field verified address point for every residence in the county. Now the health department is able to accurately geocode its data using these point and centerline files. Other local geographic data such as land parcels, contours, spot elevations, orthophotography, flood plains, and soil composition were used to implement the sewage treatment system GIS. Utilizing a Mircosoft Access data set of sewage treatment system information, existing system locations were geocoded using ArcGIS 9.0. The goal was to locate a point as close as possible to the actual sewage treatment system using existing data. To accomplish this, two geocoding services (address locaters in ArcGIS 9.1) were created. The first geocoding service was created using the “Single Field (file)” style. The reference data used was the LBRS address point file, and the “Key Field” was the field containing the address consisting of house number and street name, labeled LSN in our data set. System defaults for matching options of 80 for spelling sensitivity, 10 for minimum candidate score, and 60 for minimum match score were used. Output fields of “X and Y coordinates”, and “Standardized address” were also selected. The geocoding service was run matching the sewage treatment system address, labeled Address in our data set, and saved as a point shapefile. The second geocoding service was created using the “US Streets with Zone (file)” style with reference data being the LBRS centerline file. Fields were matched to the LBRS centerline file for “House from Left”, “House to Left”, “House from Right”, “House to Right”, “Street Name”, “Street Type”, “Left Zone”, and “Right Zone”. System defaults for matching and output fields were the same as in the first geocoding service, so that the two resulting shapefiles could be easily merged. The first geocoding service was run enabling a point to be placed on the property where the sewage treatment system is actually located. It is understood that it is not the actual location of the system on the property, only that it is matched to the property. The systems that could not be matched to the address point were then matched using the second geocoding service to approximate the system’s location on the road centerline. Unmatched records were reviewed to determine why geocoding by either method was unsuccessful. Included in the sewage treatment system database is a scanned sketch of the system layout, as documented by the licensing sanitarian. Being able to locate the sewage treatment system with a point, enabled ArcView’s hyperlink feature to be utilized (Figure 1). This now allows the sanitarian reviewing the sewage treatment system to view the sketch without having to retrieve the paper record. NOTE: The scanned image was included in the Access data set as an embedded OLE object. Extracting the path location of the sketch required the use of a Visual Basic program in order for the hyperlink feature to be utilized.  Figure 1: Image of scanned sketch of sewage system accessed from the map using a hyperlink. Results: Of the 10,426 existing sewage treatment systems records, 8,386 (80.4%) were successfully geocoded to the address point file. Manual geocode matching was performed to place as many as possible to the address point. This was done to compensate for typographical inconsistencies between the LBRS centerline file and address information in the health department’s sewage treatment system database. The remaining 2,040 records were geocoded to the address verified centerline file to approximate the system location. 1,801 (17.3%) systems were successfully geocoded to the centerline file leaving only 239 (2.3%) that were unable to be geocoded. Upon review of the unmatched records, most were older records that lacked an address, or only designated by a lot number or street name. While detailed timesaving data is not available, the sewage treatment system GIS has reduced the number of man-hours needed to manage the program. Using the GIS has eliminated the sanitarian’s requirement to review printed parcel maps only available in the auditor’s office located in another building. It has reduced time needed to leaf through paper files to review system configuration. Some site visits have been eliminated due to the ability to assess the property information using GIS. |