Method by which well location coordinates were determined for wells/locations in the PDMS.
The following values are used:
Location spot was measured on-screen using Digital Raster Graphics (Digital Topographic Maps). Measured locations are generally considered accurate to about 50 feet.
Location spot was determined by digitizing from 1:24,000-scale topographic map or by batch processing software.
All well spots in the PDMS have been visually examined and compared with earlier manually spotted well location maps at the scale 1 inch = 1 mile. Obvious discrepancies have been corrected by measuring the well locations on-screen (using a computer monitor). However, lesser accuracy is likely for the well location spots in many densely drilled areas. These spots will eventually be measured as time allows.
The spot was adjusted to a visible well location on Digital Orthophoto Quadrangle (DOQ) aerial photograph with 1-meter or better resolution.
A Digital Orthophoto Quadrangle (DOQ) aerial photograph with 1-meter or better resolution was used in the field to determine the well location, however signs of the well location are not visible on the photo (because the photo and well activity where of a different time).
Location spot with coordinates was determined by Global Positioning Satellite (GPS). Beginning in 2005, well locations in the PDMS have been determined using GPS with a best accuracy of +/- 15 feet. A comment is added in the Field Check Subtable if the GPS unit reports an error greater than 20 feet.
GPS is never used to determine elevations because the margin of error is too large.