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I .'-~ .:............. ~ HORIZONS,INC.@ I ~ -- 3600 Jet Drive . PO Box 3134 . Rapid City, SD 57709-3134 I Aerial Mapping Professionals I May 22, 2002 I Mr. Dan Bare McLaughlin Water Engineers 12596 West Bayaud Ave., Suite 200 I Lakewood, CO 80228 RE: Adams County, CO - Comanche and Wolf Creek Floodplain Delineation I Dear Mr. Bare, The services rendered on this project were performed in a manner consistent with the level of care and skill ordinarily I exercised by similar members of the photogrammetric profession of good standing. Sound and generally accepted photogrammetric principals were adhered to with regard to photo scale, equipment calibration and operator experience to achieve the accuracy required by the scope of work. The accuracy of this data is based upon the ground control survey I contracted by McLaughlin Water Engineers to Accurate Consultants, Inc., a qualified registered land surveying company. The data collection procedure was designed to meet the requirements of the National Map Accuracy Standards. Ninety pen:ent of all contours are within 1/2 contour interval except where obscured, and the If"fllllinmg ten percent of such I elevations are within one contour interval except where obscured. Ninety pen:ent of all well-defined features are positioned with 1/30th of 1 inch at map scale from their true coordinate position. The data collection procedure for orthophotography was designed to meet National Map Accuracy Standard for I orthophotography that states 90% of all visible features will fall within 1/30th of 1 inch at map scale from their tnle coordinate position. The remaining 10% of all visible features will fall within 1/15th of 1 inch at map scale. I Ground survey was collected within the project using coon:linates set to the Colorado State Plane Central Zone with NAD83 horizontal and NA VD88 vertical datums with a modification transformation to ground coordinates. Please reference the ground survey report for a full disclosure of the datum and coordinate basis of this project. Aerial photography utilizing Airbome GPS and computer-aided navigation was obtained on this project on April 28th, 2000. The flying height was I established at 7200' above the terrain to support the creation of 1 "=200' orthophotography. LiDAR technology was applied to provide the high-resolution elevation model for the creation of contours at a 2' contour interval. Stereo photogrammettic compilation was utilized to compile planimetric mapping features and edit elevation models. Cartographic editing was employed to provide map annotation and cartographic mapping features. I Mapping procedures undertaken on this project were provided by qualified mapping professionals and supervised by a Professional Engineer, Mr. Lany R Deibert. Horizons, Inc. certifies that the mapping on this project meets National MAp I Accuracy Standards. Sincerely yours, I HORIZONS, INe ~~ ~ I Lany R Deibert, PE President and General Manager I I Phone (605) 343-0280 Telecopier (605) 343-0305