N.H. Admin. Code § Lan 503.06

Current through Register No. 45, November 7, 2024

Section Lan 503.06 - Applicable Specifications

The following minimum applicable specifications shall apply to all survey classifications unless listed below:

(a) All survey field work shall be performed with methods of practice and equipment capable of attaining the tolerances as specified in Table 500.1, Survey Classification Precision and Accuracy providing for:

(1) Elimination and reduction of known systematic errors and mistakes;

(2) Sufficient redundancy to clearly state that the accuracy requirements have been achieved;

(3) Analysis of field procedures and data processing to achieve the accuracy and precisions; and

(4) Documentation verifying compliance with these standards.

(b) All survey instruments shall be kept in good repair, close adjustment, and operated according to manufacturers' specifications. A record of surveyor equipment maintenance shall be maintained by the surveyor.

(c) All pertinent information, measurements, and observations made in the field during the course of the survey shall be recorded as field notes in (d) below. Computer printouts of raw data downloaded from an electronic data collection device shall be considered a form of field notes.

(d) All field notes shall indicate:

(1) Location;

(2) Street names;

(3) Client;

(4) Instruments;

(5) Date;

(6) Field crew;

(7) Weather conditions; and

(8) Purpose of field work.

(e) Searches for evidence believed to be ferrous or magnetic in nature shall be conducted with a magnetic or metal detector when evidence is possibly buried or not visible.

(f) Survey traverses shall be based on a bearing system determined from astronomic observations, GPS observations, or from geodetic monuments incorporated into the traverse. If neither method is practical the survey shall be based on a magnetic bearing observed with a compass having a scale permitting interpolations to one-half of a degree. An alternate method shall be orientation of the survey to an existing survey. Except for farmland surveys, angle measurements of the field traverse shall be repeated 2 or more times and each set of angular measurements shall be made with the telescope both in the direct and inverted by 180 degree position.

(g) Sideshots from the traverse to monumentation or other physical features controlling the position of a property line shall be minimized. Except for farmland surveys, angle measurements to those points shall be repeated 2 or more times. Precision of measurements from the traverse points to sideshot points shall be a minimum of half the horizontal scale reading with distance measured to the hundredth of a foot. The exceptions to this shall be stone walls and fence posts which may be measured to the nearest tenth of a foot, and centerline and edges of water bodies which may be measured to the nearest foot.

(h) When feasible, vertical data shall be referenced to the North American Vertical Datum of 1988, or to the National Geodetic Vertical Datum of 1929.

(i) When vertical data is required, a minimum of 2 benchmarks shall be established on the subject tract. Benchmarks set as nails in trees shall be placed at the root collar of the tree and not the usable portion of the tree.

(j) The establishment of benchmarks shall be done with care and sufficient redundancy to ensure that the elevations are accurate and reproducible. Whenever possible and practical, a minimum of 2 known benchmarks shall be included in all level runs. All level runs shall either begin and close on separate known marks, or shall be a closed loop beginning and ending on the same known mark. Benchmarks shall be established by differential leveling using an instrument equipped with an automatic compensator or spirit level vials. The misclosure tolerance between benchmarks shall be 0.05' square root of M where M is the one-way distance in miles. The misclosure tolerance of a closed loop shall be 0.04' square root of M where M is the distance of the loop in miles.

(k) If a benchmark set or maintained by a government agency is utilized, and if that government agency seeks input from the public sector regarding the status of such monument, then a report, following the agency's guidelines, on the condition of the mark shall be submitted to the agency.

(l) Compass and tape methods may be used provided that the property lines shall be predominantly bounded by physical evidence, and shall possess a minimum number of angle points. Compass surveys shall be performed with compasses having a scale permitting interpolations to one-quarter of a degree. When compass surveys are employed, traverse lines shall be observed both as a foresight and a backsight. Taping shall be accomplished by use of a standard steel tape and corrected for slope.

(m) All topographic surveys shall be referenced to a vertical control system comprised of closed level loops.

(n) Grid lines for detailed cross-section work shall be closed and tied to the control system.

(o) Secondary traverses or level loops shall begin and end at points on the control system.

(p) When aerial photogrammetry is to be used to compile a topographic map the horizontal and vertical photo control points shall be incorporated into the horizontal and vertical control system.

(q) Measurements to physical features or improvements shall be taken with a precision compatible with the detail being located as follows:

(1) Linear measurements shall be taken to the nearest foot when locating feature such as:

a. Streams;

b. Ditches;

c. Wetlands;

d. Poles;

e. Pavement;

f. Curbing;

g. Ledge outcrops;

h. Boulders;

i. Manholes;

j. Catch basins;

k. Culverts; and

l. Signs;

(2) Horizontal and vertical angles to the features shall be taken to the nearest minute;

(3) Elevations shall be taken to the nearest hundredth of a foot on building floors, manhole rims, curbing, pipe inverts, pavement; and

(4) Natural ground elevations and water levels shall be taken to the nearest tenth of a foot.

(r) Measurements shall be taken to a precision compatible with the construction tolerances for the project.

(s) Construction layout monuments shall be of a type and character and set in a manner so as to provide a degree of permanency consistent with the terrain, physical features and intended use. Sufficient monuments and offset information shall be provided to enable the user to check the accuracy of any points or lines established there from. Any stakes that show offsets and/or cut and fill data shall also show sufficient information to identify the horizontal position of the points to which they refer.

(t) All buildings, structures, or foundation layouts shall have the perimeter closed, or in the case of a rectangle, the diagonals measured.

(u) Accuracies and classification of GPS surveys shall be as specified in Lan 503.04 Table 500.1, Survey Classification Precision and Accuracy.

N.H. Admin. Code § Lan 503.06

#5934, eff 12-9-94, EXPIRED: 12-9-00

New. #7425, INTERIM, eff 1-13-01, EXPIRED: 7-12-01

New. #7549, eff 8-25-01; amd by #7950, eff 9-10-03; ss by #9340, eff 1-1-09

Amended by Volume XXXVI Number 45, Filed November 10, 2016, Proposed by #12031, Effective 11/1/2016, Expires 11/1/2026.