R2004-08 AUTHORIZING AGREEMENT - Laserfiche WebLink

Home Browse Search

• PROJECT SCOPE Over the past several years, the City of Decatur has been maintaining annexation records through a detailed set of books showing city lots, streets and annexations with record numbers in color. The City now requires that a listing of right-of-way acreage per year annexed be calculated for accounting purposes. The best approach to use in calculating acreages is through the utilization of a Geographic Information System (GIS). The GIS will use two sets of polygons, or bounded areas, where acreages are digitally calculated. These polygons will include right-of-way areas as delineated by Macon County's parcel GIS, and annexation areas as delineated through the process described below. Services to be Provided bv the Contractor: The City's Engineering Department has been building a digital representation of the manual annexation books for several months. This data is created using a digital CAD map of City lots and right-of-ways as a backdrop as all historical annexations are drawn on top using hundreds of legal descriptions and plat maps for reference. Although the annexation map is in a digital form, it now needs to be converted from an AutoCAD format to an ESRI GIS format for calculation purposes. While converting the CAD maps to a GIS format, the data will be reprojected into a different . coordinate system to match the County's GIS format. The current coordinate system is Illinois State Plane East Zone North American Datum 1927. The new format will be Illinois State Plane East Zone North Amencan Datum 1983. Once this conversion is completed, manual realignment to the County's GIS data will begin. This will involve the inspection of each annexation and most likely the redrawing or realigning of all annexations to the new parcel base map. This ensures that all annexations will follow the appropriate boundaries as researched by the Engineering Department while drawing the original maps. Each annexation polygon will then be tagged (attributed) with the appropriate year in which the annexation was approved. Once all annexation polygons and attributes are checked for quality assurance, acreages will be calculated for all polygons. Using the County's right-of-way polygons, each annexation will be intersected to create new polygons which represent only the right-of-way portions of each annexation. The GIS will automatically calculate the acreage of these new polygons. A table listing the annexation year and acreage will be created and provided to the Engineering Department. Information to be Furnished by the City of Decatur: The City of Decatur shall furnish the following information at no charge to the Contractor: • Digital annexation map. • Macon County digital parcel base map. • • Any other information necessary for the completion of this contract. �2004 Contract between Bruce Har•ris&Associates, Inc. and the City of Decatur, Illinois p. 2