A. Purpose. The purpose of a field run topographic survey is to locate, describe, or map, or all of these, the elevations and positions of the physical features and characteristics of the surface of the earth including spot elevations, contours, and other features.
(1) The results of a topographic survey shall clearly show the results of the field and office work and shall be presented, depending on the type of professional services requested, in the form of:
(a) A plat;
(b) A worksheet;
(c) Raw data; or
(d) Adjusted data.
(2) Plats are intended for a release as stand-alone products. Worksheets and raw data are intended as components to be included in other surveying or engineering documents and are not intended as stand-alone products. Worksheets and raw data are not required to comply with this regulation.
C. Field Procedures.
(1) Field work shall be performed in accordance with accepted surveying theory, practice, and procedures as specified in this section.
(2) A surveyor in responsible charge shall adhere to the following procedures:
(a) The vertical datum of a topographic survey shall run from a known bench mark, if possible, or as otherwise specified in the scope of survey services for the project;
(b) A closed level loop, where practical, shall run through or include a second established bench mark to confirm the vertical datum;
(c) A minimum of one bench mark shall be established on or near the surveyed site;
(d) Topographic data may be obtained based on an assumed vertical datum, if the base elevation of the datum is obviously different than the existing datum, and if the final document clearly indicates that the data was obtained based on an assumed vertical datum; and
(e) Field data satisfying the requirements of these regulations shall be gathered, and the surveyor shall make a reasonable effort to maintain the data.
(1) An original plat of a topographic survey shall be a reproducible drawing at a suitable scale clearly indicating the results of the field work, computations, research, and record information as compiled, checked, and analyzed.
(2) A plat shall be prepared in conformity with the following procedures:
(a) A reasonably stable and durable drawing paper, linen, or film of reproducible quality is considered suitable material for topographic survey plats;
(b) Plats may not be smaller than 8-1/2 X 11 inches;
(c) The source of the vertical datum shall be noted on the plat;
(d) Relevant natural or artificial visible features shall be labeled and represented by a symbol on the plat in its proper location, and each symbol shall clearly indicate what is being represented or shall be labeled for identification either individually or in a separate key to symbols;
(e) Plats shall show a north arrow;
(f) A statement indicating the source of the bearings shall be made on the plat;
(g) The source of a coordinate system, if used on the plat, shall be identified;
(h) A description and the elevation of a minimum of two bench marks established on or near the site for the survey shall be indicated on the plat;
(i) Cemeteries and burial grounds found by the surveyor within the premises being surveyed shall be noted on the plat;
(j) Different line weights or delineating letters or numbers shall be used to clearly show the limits of the survey; and
(k) Spot elevations shall be shown in accordance with vertical accuracy standards as specified in §E(3) of this regulation.
(3) In addition to the criteria set forth in §D(2) of this regulation, the plat shall show the following:
(a) Caption or title and general location of the property or a vicinity map;
(d) Name and address of the firm or surveyor;
(e) A statement to the effect that a licensee either personally prepared a topographic survey or was in responsible charge over its preparation and the surveying work reflected in it, all in compliance with requirements set forth in Regulation .12 of this chapter; and
(f) Seal and signature of the surveyor who personally prepared or was in responsible charge over the preparation of the topographic survey.
(1) Horizontal tolerances for topographic mapping shall meet the following accuracy standards of this subsection. On maps with publication scales larger than 1:20,000, not more than 10 percent of the points tested shall be in error by more than 1/30 inch, measured on the publication scale, and on maps with publication scales of 1:20,000 or smaller, 1/50 inch. These limits of accuracy shall apply in all cases to positions of well-defined points only. Well defined points are those that are easily visible or recoverable on the ground, such as monuments or markers, including:
(a) Bench marks;
(b) Property boundary monuments;
(c) Intersections of roads;
(e) Corners of large buildings; and
(f) Other similar points.
(2) In general, what is well defined may also be determined by what is plottable on the scale of the map within 1/100 inch.
(3) Vertical tolerances for topographic mapping shall meet the accuracy standards of this subsection. Vertical accuracy, as applied to contour maps on all publication scales, shall be such that not more than 10 percent of the elevations tested shall be in error more than 1/2 the contour interval. In checking elevations taken from the map, the apparent vertical error may be decreased by assuming a horizontal displacement within the permissible horizontal error for a map of that scale.