WORK IN PROGRESS

7-31-03

The Vanderburgh County Surveyor’s Office is undertaking the reclaiming and locating of existing “apparent” section corners. At this time the office is only interested in section corners and quarter corners (1/2 mile corners). The corners are being located with dual frequency GPS equipment in the static mode. A normal corner location will be based on two HARN points and will be adjusted by least squares network adjustment utilizing those HARN points used in the survey. It is this office’s intent to have the coordinates and elevations of the corners to be of high enough accuracies that engineers and surveyors can use these corners for their horizontal and vertical control on “local surveys.” It is the hope of this office that future engineering surveys and land boundary surveys will be done with Indiana state plane coordinates, based on the control established.

As stated in the above paragraph, this office is currently concentrating on locating existing corners. This office has 60 to 80 corners calculated to reset based on the information so far gathered from previous section corner locations. These corners will be reset basically on an “as-needed basis." It is the Surveyor’s position that all apparent corners should be located first, then the office will spend time resetting the lost or obliterated corners. As of the above date, the Surveyor has located approximately 564 corners. There are approximately 800 section corners to locate or re-establish in the county. It is this office’s goal to establish all section corners with state plane coordinates and elevations. This office believes that it has completed approximately 72 % of corner replacement and restoration.

Currently, section corners (1/2 mile and mile corners) in Township 6 South, Range 11 West (Perry and German Civil Townships) are almost completely re-established. About 1 to 2 corners are left to locate and/or re-establish. The crew has moved into Township 5 South, Range 11 West (German and Armstrong Civil Townships) and will attempt to complete that township in the next month. Currently, this office has approximately 6 corners left to set in Township 5 South, Range 11 West.

Office personnel are currently working on updating the section corner reference cards (Tie Cards). The old references on file are being redrawn into AutoCAD drawing files. Currently, this office has completed the AutoCAD part of the project and is nearing completion of the process of proofreading the drawings. Then, these files will be posted on the Internet (GIS) for public use in the very near future.

For additional information pertaining to the FEMA flood plain maps, please read the Surveyor’s Annual Report on regulated drains attached to this Web site.

In addition, the surveyor’s office has been conducting some in-house test of the new National Geodetic Survey’s OPUS program. OPUS allows users to submit their GPS date files in Rinex format to NGS, where the data will be processed to determine the position using NGS computers, software, and various COORs stations. This office has found the program to be easy to use, and the results seem to be very accurate. We have tested the program against the published coordinates available for various HARN points in the county and found the calculated coordinates to be within 0.02 feet horizontal and about 0.30 feet vertical. It appears to be a relatively simple way to use one receiver to determine accurate positions. The NGS recommends collecting at least two hours of data, with three to five hours yielding the best results. The receiver must have the ability to collect dual frequency GPS signals.

The Vanderburgh County Surveyor’s GIS Web site is up and running. This site has information such as coordinates and elevations (NAD 1988) for apparent section corners, new contours for the County, street locations and names, subdivision boundaries and names, individual parcel tax ID numbers, etc. This site will not be static and will be updated continuously. The site has added a few NGS vertical benchmarks (BM) into the GIS system for user review. The benchmarks were entered based on scaled latitude and longitude at this time. At a later date, these benchmarks may be resurveyed using GPS equipment to attain more accurate horizontal positions; furthermore, the section corners in the GIS have elevations as well as horizontal coordinates.

Furthermore, the Surveyor’s Web site has two new links on the Electronic Records page. The first one is the Indiana Geographical Survey showing the location of Indiana coal mines (surface and underground). The second link illustrates the Indiana Department of Natural Resources (DNR) Division of Water and its county benchmark information.

There have been numerous discussions and arguments about the intent of the “old” Surveyors Books A-E. Research will be undertaken to determine the origination of the Legal Land Survey Statute and the intent of the books. Some local surveyors in the area are of the opinion that the books are legal survey books. This surveyor is not of that opinion, but research will be conducted to determine the answer. As of this date, the Vanderburgh County Surveyor’s Office still has had no response from any of the office’s various contacts. This office now has the ability to scan 11” x 17” documents and is discussing scanning the old survey record books onto the Internet if the quality can be legible, etc.

During 1939 and 1940 a large control survey, both horizontal and vertical, was undertaken in the city. In the future this survey will be reclaimed and converted to the NAD 1988 datum currently used in the Evansville/Vanderburgh GIS.

Any help from the engineers and surveyors in the local area in locating corners is greatly appreciated. This combined effort will better serve Vanderburgh County residents.

D. McDonald, PE, LS

812-435-5210

DMCDONALD@VanderburghSurveyor.com

Return to the Vanderburgh County Surveyor's Home Page