Chapter 16.16
TECHNICAL STANDARDS FOR
LAND SURVEYORS
Sections:
16.16.020 Standards – Land titles and location.
16.16.050 Field measurement standards for traverse surveys.
16.16.010 Adoption.
The board of County commissioners adopts the standards published by the State Department of Natural Resources as the technical standards for land surveying as required under the County subdivision and plat ordinance until further publication of standards is made, as required by RCW 58.17.260, and subsequently adopted by the board by resolution. (Res. 146-1971)
16.16.020 Standards – Land titles and location.
A. Every parcel of land whose boundaries are surveyed by a licensed surveyor should be made conformable with the record title boundaries of such land. The surveyor, prior to making such a survey, shall acquire all necessary data, including deeds, maps, certificates of title, centerline and other boundary line locations in the vicinity.
B. He shall compare and analyze all of the data obtained and make the most nearly correct legal determination possible of the position of the boundaries of such parcel. He shall make a field survey, traversing and connecting all available monuments appropriate or necessary for the location and coordinate the facts of such survey with the predetermined analysis. Not until then shall the monuments marking the corners of such parcel be set, and such monuments shall be set in accordance with the full and most satisfactory analysis obtainable.
C. The subdivision of land shall conform to the statutes of the state and as prescribed by the United States government surveys and the instructions relating thereto. (Res. 146-1971)
16.16.030 Land description.
Any description written for conveyance or other purpose defining land boundaries shall be complete and accurate from a title standpoint, providing definite and unequivocal identification of the lines or boundaries, and definite recitals as to use or rights to be created through such descriptions. Any form of description, regardless of presence or absence of any or all dimensions, but specifically tying to adjoiners, which fulfills the foregoing conditions, is acceptable. However, such description, insofar as possible, in addition to all necessary ties to adjoiners, shall contain sufficient data of dimension, determined from accurate field survey, to enable the description to be completely platted. The following information shall be included in land description as minimum requirements:
A. Lot or tract in a recorded plat.
1. Lot and block number or designation;
2. Addition or subdivision name and number and its location by section, township, range and meridian;
3. Easements, use, rights and exceptions;
4. Plat book and page number of recorded plat;
5. Recording office.
B. Lot or tract described by metes and bounds.
1. City and/or county and state;
2. Section, township, range, meridian, donation land claim, grant or treaty;
3. Measurement to section, grant or treaty corner or recognized subdivision corner thereof with physical description of such corners;
4. A traverse of the boundary giving:
a. Place of beginning and/or initial point,
b. Bearings in degrees, minutes and seconds,
c. Distances in feet to the nearest one hundredth,
d. State name of adjoiners where applicable, giving deed record and page number, fee number and recording office,
e. State if course is a dividing line of a section subdivision when applicable,
f. Give bearing reference meridian,
g. If area is given, indicate to the nearest one hundredth acre,
h. Easements, use or rights,
i. Ties to physical features where practical. (Res. 146-1971)
16.16.040 Maps.
A. Every land survey requires a map properly drawn to a convenient scale, showing all the information developed by the survey; also a proper caption, proper dimensions and bearings or angles, and references to deeds and other matters of record pertinent to such survey, including monuments found and set.
B. Boundary survey maps shall include the following:
1. Title and purpose of survey;
2. Land surveyor certification by showing name, address, license number, signature and seal;
3. Date;
4. North arrow and bearing reference;
5. Deed calls and reference to control monuments;
6. Indicate monuments found and set;
7. Bearings or angles in degrees and minutes and seconds and distances to the nearest one hundredth of a foot;
8. Traverse must mathematically close;
9. Names of adjoiners;
10. Indicate gaps or overlapping boundaries;
11. Physical appurtenances (fences, structures, etc.) if required in surveys for title insurance, to indicate encroachment, lines of possession or other pertinent reasons. (Res. 146-1971)
16.16.050 Field measurement standards for traverse surveys.
Field measurement standards for traverse surveys which determine boundaries, subdivisions and land titles are as follows:
A. Linear Closure.
1. City: central and local business and industrial areas — 1:10,000 min.
2. City: residential and subdivision lots — 1:5,000 min.
3. New subdivision boundaries for residential lots and interior monument control — 1:10,000 min.
4. Suburban: residential and subdivision lots — 1:5,000 min.
5. Rural: cultivated areas — 1:5,000 min.
Preliminary or reconnaissance surveys shall maintain an accuracy of not less than one part in 5,000, except in those cases where general information only is to be obtained and no precise monumented corners are to be created.
B. Angular Closure.
1. Where 1:10,000 minimum linear closure is required, the maximum angular error in seconds shall be determined by the formula 10. n, where “n” is the number of angles in the closed traverse with the number of azimuth courses between azimuth checks not to exceed 25.
2. Where 1:5,000 minimum linear closure is required, the maximum angular error in seconds shall be determined by the formula 30. n, where “n” is the number of angles in the closed traverse with the number of azimuth courses between azimuth checks not to exceed 36.
C. Major Network Control. Classification and standards of accuracy of geodetic control surveys.
1. Basic Geodetic Program.
a. A basic program for establishing geodetic control described in these classifications is in progress to provide adequate spacing as well as sufficient strength and accuracy to meet the needs and satisfy the requirements of engineers and scientists engaged in the development and conservation of the resources of the United States.
b. The horizontal control network of the United States consists of a framework of arcs of triangulation extending north to south and east to west and crisscrossing each other at intervals of about 60 miles. The areas between the arcs are subdivided with networks of single triangles, supplemental arcs or traverses.
c. The basic program for the ultimate development of the vertical control net of the United States is to form loops of first-order lines spaced at 60-mile intervals, divided by lines of second-order leveling spaced at 25- to 35-mile intervals. In areas where the interest and need for leveling require closer spacing the first-order spacing may be less than 60 miles. In areas where conditions require it, a spacing of second-order lines at six-mile intervals may be established. The reference datum shall be mean sea level.
2. Horizontal Control. Generally, the density of permanently marked control points should be in direct ratio to land values. In metropolitan areas and along interstate highway systems a spacing at one- or two-mile intervals may be required and in rural areas of high land value a spacing of three to four miles may be desirable. Although wider spacing may suffice for federal topographic mapping, closer spacing may be needed for property surveys, highway programs, transmission lines, reclamation projects and numerous other engineering activities. The more closely spaced stations should be so situated that they are readily available to local engineers.
3. Triangulation.
a. Economic, engineering and scientific progress has brought an increasing number of requests for higher accuracies in basic first-order triangulation. The range of accuracies is so great that it is necessary to divide first-order into three classes so that satisfactory standards of accuracy can be established.
First-order, Class I. The high value of land in urban areas, the study of small systematic movements in the earth’s crust in areas subject to earthquakes and the testing of military equipment for the national defense require that the triangulation used by engineers and scientists in these varied activities should have an accuracy of at least one part in 100,000. Extensive surveys of this nature should make adequate connections with the arcs that make up the national triangulation network. Surveys of such accuracy are designated as Class I of First-order.
First-order, Class II. The basic national horizontal control network consists of arcs of triangulation spaced about 60 miles apart in each direction, forming areas between the arcs which are approximately square. The arcs are planned as chains of quadrilaterals or central point figures, so that the lengths of the sides may be computed through two different chains of triangles. The program for the completion of the network in the United States includes establishing area networks of triangulation within these squares or loops formed by the arcs. To maintain satisfactory mathematical consistency within the area networks, these basic arcs should be measured with an accuracy of at least one part in 50,000. Most of these primary arcs have closures in length and position which are of the order of one part in 75,000 or one part in 100,000. Triangulation of this standard of accuracy is designated as Class II of First-order.
First-order, Class III. There are many additional demands for first-order triangulation within this national framework and in some cases even independent of the national net. State, County and private engineering organizations as well as branches of the federal government have need for horizontal control that would have a minimum accuracy of one part in 25,000. Surveys of this accuracy have long been recognized both nationally and internationally as first-order and have attained the status of a widely accepted standard.
b. In the adjustment of the first-order national network, the surveys of Class I will have precedence and should not be distorted to adjust them to surveys executed under the specifications of Class II. When the surveys of Class III are rigidly adjusted to the basic network, their accuracy should be improved.
c. The placing of first- or second-order control points within the loops of the basic network requires the extension of area networks, cross arcs or traverses. These specifications list two classes of second-order triangulation.
Second-order, Class I. This class includes the network covering the areas within the arcs of the basic network and, if area nets are not feasible, it includes the cross arcs which would be used to subdivide the area. The internal closures of this class of survey should indicate an average accuracy of one part in 25,000, with no portion less than one in 20,000.
Second-order, Class II. This class of triangulation is used to establish control for hydrographic surveys along the coastline and inland waterways. It may also be used for further breakdown of control within any of the higher classes of triangulation. This class of survey or any of the higher classes may be used by engineers for controlling extensive property surveys. The minimum accuracy to be allowable in Class II of Second-order is one part in 10,000.
Third-order Triangulation. Triangulation of this order should be supplemental to triangulation of a higher order for the control of topographic or hydrographic surveys, or for such other purposes for which it may be suitable. Although it will usually be established as needed for a specific project, third-order triangulation should be permanently marked, and azimuths should be observed to visible prominent objects, so that the work may be available for future projects and miscellaneous uses in the area. Points located by third-order triangulation may be expected to have an absolute position determination within 10 feet or less in relation to the adopted datum defined by higher-order positions in the area. The work should be performed with sufficient accuracy to satisfy the standards listed in Table I, on file in the planning department.
d. Standards for surveys below third-order are not included in these classifications.
4. Bases. Bases for the control of the lengths of lines in the triangulation should be measured by appropriate methods and instruments, so that the standards in Table I are satisfied. Recent developments in electronics indicate that accuracies comparable to those obtained with invar tapes may be expected from the Bergstrand geodimeter or similar instruments. The intervals between bases should be such that the standards regarding strength of figure (ΣR1) also are satisfied.
5. Traverse.
a. Traverses are used to supplement all orders and classes of triangulation and to provide closer and more adequate spacing of horizontal control points. A triangulation net in an urban area provides a framework for a complete traverse network of first- and second-order accuracies. It is neither economical nor feasible to use triangulation for this closer spacing. There are some sections of the United States in addition to these urban areas where traverse can be used efficiently to subdivide the basic network and provide the fundamental spacing of control specified in the national program.
b. First-order traverses should preferably be connected to first-order triangulation stations of Class I or Class II. If they are connected to Class III of first-order they might be used and given some weight in the adjustment of this class of triangulation. The minimum requirement of accuracy for a first-order traverse is one part in 25,000, yet first-order traverse networks, properly executed, will average about one part in 40,000. This value is expected and desired. Detailed standards are listed in Table II, on file in the planning department.
c. Traverses of second- and third-order accuracy are tied to triangulation or traverse of the same or higher order. They are used extensively for cadastral or property surveys and mapping. For property surveys, the value of the property should, in general, determine the accuracy to be used. For map control, the scale of the map and the positional accuracy required usually govern. Details of these orders of traverse are also listed in Table II.
6. Trilateration. Electronic techniques are increasingly used for the measurement of distances and, through the geometric combination of these distances, networks of trilateration or traverse are developed. In general, the same standards in regard to position closure may be applied as are used in triangulation and traverse.
7. Vertical Control – Leveling.
a. One of the most important items in the development of a control level net is establishing marks that will remain stable. Releveling has shown that there is considerable vertical movement of bench marks. In some sections of the country there are many factors contributing to vertical change, such as removal of underground water, removal of underground gas and oil, frost action, settling of the soil due to increased moisture content during the rainy seasons, changes in the underground water table, fault lines, earthquakes, etc. Some of these are so deep-seated that in some areas it is impossible to establish a mark that will remain stable. However, some of these vertical changes can be overcome by installing “super” or “basic” marks at intervals along the line of leveling. The usual practice is to establish a concrete post type mark at one-mile intervals along a line of first- or second-order leveling, with a “basic” mark at five-mile intervals. Releveling has shown so many vertical changes that it is advisable to consider releveling first-order lines at least at 25-year intervals, and in areas where the vertical change is rapid, releveling at least at five-year intervals. Where vertical change has reached a rate of one foot per year, releveling every two years may be advisable. In addition to the determination of the elevations of regular bench marks, which are installed along the routes of precise level lines, supplementary elevations should be determined at points such as road intersections, railroad crossings, etc., which can be readily identified in aerial photographs.
b. In first-order leveling the requirement is for a forward and backward running to agree within 0.4 mm times the square root of the length of the section in kilometers. If second-order leveling is run with the same equipment as first-order, it can be single run, with loop closures within the criterion 8.4 mm times the square root of the distance around the loop. In remote areas where a second-order line is longer than 25 miles due to the fact that routes are unavailable for an additional network development, the line should be double-run. This is defined as Class I of Second-order. The single-run area leveling is defined as Class II of Second-order. Summaries of these classifications are listed in Table III, on file in the planning department.
c. Third-order leveling should be used to subdivide the area surrounded by first- and second-order leveling and should be performed so that the standards in Table III are satisfied. Trigonometric leveling may be considered as fourth-order leveling, and the elevations thus determined are listed with the triangulation data. (Res. 146-1971)