CO Land Surveyor cheat sheet

Retracement follows the footsteps of the original surveyor; it does not re-establish lines by proportionate measure unless the original monuments are lost and the record evidence supports it.

Priority of evidence: natural monuments, then artificial monuments, then courses and distances, then area (federal rule). Intent of the original parties controls over mathematical precision.

A boundary line is fixed where the original monument stood; subsequent movement or destruction does not move the legal line.

Adverse possession in Colorado requires 18 years of actual, adverse, open, notorious, exclusive, and continuous possession; payment of taxes is not a statutory element but is evidence of claim.

Unwritten rights such as prescriptive easements require 18 years of adverse use; easements by necessity arise from unity of title and strict necessity, not convenience.

Ambiguity in a deed is construed against the grantor; a call for a monument generally prevails over a call for a distance or area.

Corner search: check the record, plat, and field notes, then search for original evidence within a reasonable radius; accept the best available evidence and document all found and set monuments.

Occupational lines and possession lines may define practical boundaries but do not, standing alone, override the written deed description.

A boundary survey should show the record description, the measured position, found monuments, and any discrepancy; the client must understand that a survey is an opinion, not a guarantee of title.

The PLSS is based on principal meridians and base lines; Colorado has several, including the Sixth Principal Meridian and the New Mexico Principal Meridian, plus other principal meridians in the state.

Townships are 6 miles square, containing 36 sections of 1 square mile (640 acres); sections are numbered boustrophedon from the northeast corner, 1 through 36.

Standard parallels (correction lines) and guide meridians limit the accumulation of error; standard parallels are generally every 24 miles north of the base line.

Section corners include standard corners, closing corners, quarter-section corners, and meander corners; meander corners are set at the intersection of survey lines with navigable water bodies.

A regular quarter-section corner is at the midpoint of a section line; a closing corner is set where a surveyed line closes on a previously established line and may not be at midpoint.

The 1873 and later rules: when original corners are lost, re-establish by proportionate measurement between the nearest existing original corners, preserving the record of the original survey.

Fractional lots along navigable waters or reservation boundaries are numbered and their areas computed from the actual meander lines, not from 40-acre nominal divisions.

Subdivision of a section: quarter sections by quarter-quarter corners; the center quarter-section corner is common to four quarter sections and is set at the intersection of lines connecting opposite quarter-section corners.

A cadastral survey by the BLM is an official survey; private surveys retracing federal corners must follow the 2009 Manual of Surveying Instructions and report discrepancies to the BLM.

NAD83 (2011) and NATRF2022 are horizontal datums; NAVD88 is the vertical datum, realized through tidal benchmarks and replaced by NAPGD2022. Datum tags must accompany every coordinate.

SPCS83 in Colorado uses Lambert Conformal Conic projections with zones North, Central, and South; scale factor combines grid scale and elevation (sea-level) factor.

Grid distance = ground distance × combined factor, where combined factor = grid scale factor × elevation factor; elevation factor ≈ R/(R + h) using mean Earth radius.

State plane coordinates are grid coordinates, not ground coordinates; a surveyor must state whether distances shown are grid or ground and apply the combined factor to convert.

GNSS static observations yield geodetic coordinates; OPUS solutions provide NAD83 (2011) coordinates and orthometric heights with reported accuracies.

Geoid models (GEOID18, and newer) convert ellipsoid heights to orthometric heights: H = h − N, where N is the geoid undulation.

A control network should have redundant observations and a least-squares adjustment; report reference variance, standard deviations, and error ellipses.

Traverse closure: linear misclosure divided by total traverse length gives relative precision; angular misclosure is compared with allowable error based on the number of angles.

Monument stability and centering errors dominate short-baseline GNSS work; use longer occupations and check ties to published control before accepting a network.

Coordinate geometry: northing = distance × cos(azimuth), easting = distance × sin(azimuth); inverse computes azimuth and distance from coordinate differences.

Azimuths are measured clockwise from north; bearings are measured from north or south toward east or west and must state the quadrant.

Traverse area by coordinates (shoelace): 2A = Σ(Xi × Yi+1 − Xi+1 × Yi), taken in order around the traverse; the sign indicates direction.

Curve formulas: tangent T = R tan(Δ/2); length L = RΔ (Δ in radians); chord C = 2R sin(Δ/2); external E = R(sec(Δ/2) − 1); middle ordinate M = R(1 − cos(Δ/2)).

Degree of curve: arc definition D = 5729.578/R; chord definition D = 2 arcsin(50/R). Colorado highway work typically uses arc definition.

Vertical curves: parabola with rate of change r = (g2 − g1)/L; elevation at distance x: y = g1x + rx²/2; high or low point where slope equals zero.

Leveling: elevation difference = backsight − foresight; loop misclosure is distributed in proportion to distance or number of setups; curvature and refraction correction ≈ 0.0206 D² (D in hundreds of feet).

Least-squares adjustment distributes residuals by observation weights; weights are inversely proportional to variance, and a blunder check should precede adjustment.

Measurement uncertainty: report standard deviations and confidence intervals; 95% confidence uses a coverage factor of about 1.96 for normal distributions.

Construction staking converts design coordinates to field positions; check design coordinates against control and report any discrepancy before staking.

Horizontal and vertical control must be established and held; benchmarks and traverse points should be set outside the construction limit of disturbance.

Subdivision plats in Colorado are governed by municipal or county subdivision regulations and must be prepared by or under the supervision of a licensed land surveyor.

Floodplain and drainage design rely on FEMA FIRM data; elevations are referenced to NAVD88 and must match the datum used in the design.

ADA accessibility and drainage grades require precise control: typical minimum slope for paved surfaces is 1% to 2%, and ponding must be avoided.

Machine control and GPS-guided grading require a site calibration tying design coordinates to local control; verify calibration residuals before production work.

As-built surveys compare constructed improvements with design; report deviations and verify that monumentation and easements are in place.

Easement and right-of-way lines must be staked and shown on improvement plans; utility conflicts are identified through record research and potholing.

Colorado requires a surveyor's seal and signature on plats and reports; unlicensed practice is prohibited under Title 12, Article 120, C.R.S.

Colorado licenses land surveyors through the State Board of Licensure for Architects, Professional Engineers, and Professional Land Surveyors under Title 12, Article 120, C.R.S.

Licensure requires education, experience, and examination; a licensed surveyor must obtain continuing professional development hours each renewal cycle as set by the Board.

Sealing and signing work: a licensee may seal only work they performed or directly supervised; sealing work beyond competence is a violation.

The surveyor's duty runs to the public health, safety, and welfare; conflicts of interest must be disclosed, and contingent fees that compromise professional judgment are prohibited.

Colorado boundary surveys must be filed with the county in specified circumstances, and plats and monument records are public records.

A land surveyor may not practice law; title opinions and legal interpretations of deeds should be referred to counsel, though boundary evidence analysis is surveying.

Confidentiality: client information is not disclosed without consent except as required by law or to prevent serious harm.

Competence and supervision: field and office work must be performed under responsible charge; unlicensed staff may perform tasks but not sign or seal.

Statutory and professional standards require accurate records, monument perpetuation, and reporting of errors; falsifying field data is grounds for discipline.