Continuous Operating Reference Station
Land Survey Services System Manual for Horizontal and Vertical Datum
This Manual was prepared for the benefit of those doing work in the City of Scottsdale pertaining to ground surface measurement. The staff of Inspection Service's Land Survey Unit compiled the data found within the Manual.
Published by Land Survey Unit, Inspections and Land Survey Services Division and the Planning and Development Services Department. (Revised: 11/3/98)
Table of Contents
- Station Numbering System
- Horizontal Control System
- City of Scottsdale - Prime Network
- Vertical Control System
- Minimum Standards for Land Boundary Surveys
- Data Column Explanation
Station Numbering System
The City of Scottsdale Land Survey Unit has elected to utilize the GPS station numbering system established by Hunsaker and Associates and described in their report of 1990. A station number has four(4) significant digits that indicate the Township and Range, Section number and the particular corner of the section. There are a few rules regarding the station numbering system and are explained as follows:
The first digit of the station represents the Township code.
The middle two digits represent the Section number with single digit Section numbers being preceded by a significant Zero.
The fourth digit represents a Section corner code. When corner is common to two Townships or Ranges, use code for Township to North and Range to East.
Corners unique to one Section, yet not in the Northeast quarter, use corner codes 5 through 9 (see Corner Code Table).
|Township Codes||Corner Codes|
|T. 6 N., R. 5 E.||= 0||1 =||NORTH|
|T. 5 N., R. 4 E.||= 1||2 =||NORTHEAST|
|T. 4 N., R. 4 E.||= 2||3 =||EAST|
|T. 3 N., R. 4 E.||= 3||4 =||CENTER|
|T. 2 N., R. 4 E.||= 4||5 =||SOUTHEAST|
|T. 1 N., R. 4 E.||= 5||6 =||SOUTH|
|T. 5 N., R. 5 E.||= 6||7 =||SOUTHWEST|
|T. 4 N., R. 5 E.||= 7||8 =||WEST|
|T. 3 N., R. 5 E.||= 8||9 =||NORTHWEST|
|T. 3 N., R. 6 E.||= 9|
The Horizontal Control System
The basis of the horizontal control system for the City of Scottsdale is the Land Survey performed by Hunsaker and Associates (H&A) as published on January 17, 1991. H&A values were achieved through the use of the Global Positioning System (GPS). H&A data in their report included latitude and longitude values along with respective state plane coordinate values.
The City's Land Survey Unit converted the H&A state plane coordinate values into a modified coordinate system for the purpose of establishing a horizontal basis for the City's Geographic Information System (GIS) . The method used in creating the modified coordinate system is unique but produced values compatible with the varying surface of the earth. The modified coordinate system will be hereinafter referred to as the "City Grid".
Station 7192 of the H&A report is the initial point of the City Grid. Station 7192 was also a primary control station of the H&A network. The state plane coordinate of this station has the same numerical value as the City Grid bearing the same station number. All other state plane values will be different when compared to City Grid values. The bearing and distance value determined by inversing between any two City Grid coordinates will be equal to actual field measurements on the surface. Station 7192 is a 1919 Government Land Office (GLO) brass cap on a 2 inch iron pipe 0.88 feet above the surface representing the Northeast corner of Section Nineteen (19), Township Four(4) North, Range Five(5) East of the Gila and Salt River Meridian, Maricopa County, Arizona, Latitude 33° 41' 01.02932" North, Longitude 111° 52' 26.82154" West and being also the intersection of Deer Valley Road and 96th Street.
A scale factor of 0.999801686 (ASF) was determined as the common scale factor. The common scale factor represents the average of all H&A station scale factors for stations within the city. The common scale factor was applied to each state plane coordinate station inversed from the initial point. This method yielded reasonable accuracy when comparing any station to station dimension for surface values.
The GIS has as its origin the City Grid as established through the above described process. The City Grid coordinates are a part of this document and are to be used when doing work within the City of Scottsdale having to do with land measurement and when data is presented to the city for its consideration.
ground distance = ASP Grid Distance ÷ ASF
5000.992 = 5000.000 ÷ 0.999801686
To ASP Distance = COS ground distance x ASF
5000.000 = 5000.992 x 0.999801686
ASP refers to Arizona State Plane.
COS refers to City of Scottsdale.
ASF refers to Average Scale Factor for COS.
City of Scottsdale Prime Network
The Vertical Control System
The prime benchmark used for the purpose of establishing a vertical network for the city is NGS mark "U 365" having a NAVD 88 elevation of 1449.708 feet (COS NGVD29 elevation of 1447.935 feet). The orthometric height was determined by differential leveling and adjusted by NGS in June, 1991.
Mark "U 365" is a Bench Mark Disk set by Coast and Geodetic Survey in 1967 and stamped "U 365 1967". Set in rock outcrop and flush with the ground. Horizontal coordinates at an accuracy of +/- 6 seconds are Latitude = 33 31 23 N and Longitude = 111 58 11 West.
Land Survey personnel have performed many leveling circuits throughout the city to fortify a consistent system. The prime equipment used in the leveling process was a Wild NA2002 electronic level utilizing a bar coded leveling rod. Distance balanced readings were observed and recorded electronically as well as noted in a hardbound fieldbook.
Elevations published herein are those that have been verified in the leveling process. Monuments with elevation values have actually been observed in the field by city personnel and are described on pages 14 thorugh 45 in the Data Table section of this manual. It is requested that any person occupying a City of Scottsdale horizontal and/or vertical point/monument, and who's measurements differ in description and/or value, to immediately notify the Land Survey Unit to report their findings. It is the desire of the Land Survey Unit to correct and update this manual whenever discrepancies are found or reported by internal or external sources. City of Scottsdale Land Survey Unit phone number (480) 312-5782.
International System of Units, or simply SI, from the French name Le Système International d'Unités. The name metric comes from the fact that one of the base units of this system is the metre.
The metric system was introduced in France in year 1790. In 1866 the United States Congress proclaimed the metric system to be legal in the United States. Metric standards were defined by an international treaty. The United States signed the treaty in 1875, and Canada, in 1907.
The METRIC system will be our future system of measurement. Included with the Data Tables herein you will find along with the "X", "Y", "Z" values in the English system, the corresponding metric value.
Although the City of Scottsdale does not presently require submittals in metric, we must keep in mind the general direction of governmental agencies throughout the country adopting the metric system. Measurements made on the surface of the earth for Federal, State and County highway construction projects must conform to the metric system. This City may someday, mandate the use of metric, if only to keep in step with movement of conversion.
The Arizona Department of Transportation (ADOT) Intermodal Transportation Division has published the METRIFICATION GUIDELINE (3rd edition), January, 1996, to provide assistance in the usage of Metric. The ADOT Office of Metrication have a training manual for the Basic Metric System available to the public.
SI units - Conversion to metres: (* DENOTES VALUE EXACT)
Foot multiply by 3.048 x 10 -1*
Mile (International) multiply by 1.609 344 x 10 -3*
Mile, Nautical (Int'l & US) multiply by 1.852 x 10 -3*
Rod (US Survey) multiply by 5.029 *
Yard multiply by 9.144 x 10 -1*
Meters = Horizontal distance (SI units) x 0.3048
100.00 (meters) = 328.084 (SI feet) x 0.3048
SI feet = Meters ÷ 0.3048
328.084 (SI feet) = 100.00 (meters) ÷ 0.3048
Minimum Standards for Land Boundary Surveys
The Code and Rules of the Arizona State Board of Technical Registration effective May 1, 1995 state the "Minimum Standards for Arizona Land Boundary Surveys". It is the responsibility of the Professional Land Surveyor to adhere to good and accepted practices when providing land survey services in the City of Scottsdale.
Land boundary surveys and legal descriptions are prerequisite to the division of any land parcel. Observance of these minimum standards should be considered whenever the work is subject to the City review. The minimum standards section of the Code and Rules is reproduced hereon for the benefit of the public.
Minimum standards for Arizona Land Boundary Surveys
The following statements of standards for surveying practice are promulgated as minimum standards governing the creation, establishment, retracement or resurvey of land boundaries within the State of Arizona. Applicable statues and regulation are to be observed in addition to these minimum standards of practice.
Responsibility for adherence to the minimum standards rests with the registered land surveyor in responsible charge of work.
- The land surveyor must make a diligent search for pertinent record documents. Copies of applicable deeds, maps, title report or title opinions may be necessary. If the subject property is referenced to or described as an aliquot part of the U.S. Public Land Survey System, or a fraction thereof, relevant U.S. Government plats, field notes, appropriate Manual of Surveying Instructions and special instructions should additionally be consulted, when appropriate.
- The land surveyor must thoroughly examine the information and data required.
- The land surveyor must diligently search for and identify monuments and other physical evidence which could affect the location of the subject property's boundaries. A reasonable attempt must be made to recover controlling monuments for references thereto. The positions of controlling monuments which have been obliterated should be recovered or reestablished using the best available evidence. Physical evidence of apparent use and possible rights in the subject property by others should be evaluated. Lines of possession and occupation must be located, described, and where practical, an age determination made.
- The land surveyor must conduct field measurements necessary to adequately relate the position of all apparent evidence pertinent to the boundaries of the property. All findings resulting from the field investigation must be accurately and completely recorded and retained permanently.
- The land surveyor must make computations to verify the correctness of field data acquired and to confirm that measurement results are within acceptable tolerance limitations. Computations must be made to determine the relative positions of all found evidence.
- In the event of a material discrepancy or disagreement with the measurements or monumented corner positions of another land surveyor, the land surveyor must make a reasonable attempt to contact the other land surveyor and attempt to resolve the disagreement.
- The land surveyor must make an analysis, reach a final conclusion and set monuments so as to represent the location consistent with the best evidence available of corner positions and boundary lines. The land surveyor must advise the client of discrepancies which raise doubts concerning the boundary lines of the subject property and he should provide the client with a copy of the survey report.
- All monuments, whether set or found, must be described and specifically identified as set or found, whenever shown on maps or referred to in documents prepared by the land surveyor. Descriptions of monuments must be sufficient in detail to readily facilitate future recovery and to enable positive identification, including map references. Monuments required by this section shall be metal, magnetically detectable, not less than one-half inch in diameter, not less than sixteen inches in length, and shall bear the land surveyor's registration number affixed, except however, the monument for a corner which falls upon solid rock or concrete shall be metal, magnetically detectable, firmly embedded, and stamped with the land surveyor's registration number.
- The land surveyor shall prepare a scaled drawing of the results of survey for presentation to the client unless adequate existing information is available. In cases where a certification is required by state or local ordinance, the land surveyor must certify only those matters personally known to be absolutely true and must declare all other items only to the limit of the land surveyor's knowledge and belief.
- The land surveyor must prepare and cause to be recorded corner records and record of survey documents if a material discrepancy exits in angular and/or lineal calls as compared with new survey values as defined under Measurement Specifications paragraph 2 of these standards of practice
When a land surveyor is called upon to prepare a legal description of real property, the land surveyor must include the following:
- Sufficient caption, body and, where applicable, qualifying clauses.
- Clearly stated relationship between the real property being described and the survey control or basis of unique location.
- Clearly stated basis of bearings or language which otherwise makes definite the method of direction and orientation for the lines of the subject property being described and the survey control related thereto when applicable.
- Full and complete citations to maps, plats, documents, and other matters of record, fact or pertinence, which are intended to be incorporated into and made a part of the legal description by reference thereto.
- When called out, complete and detailed descriptions of physical monuments, both natural and artificial, such as to facilitate future recovery and to enable positive identification.
- When appropriate, incorporated either directly or by citation, sufficient data to enable a check of mathematical closure for the subject property being described.
- The land surveyor's validated Arizona seal.
Measurements for the performance of land surveys as defined in A.R.S. *32-101(B)(19)(a)(b) & (c) (Land Surveying Practice shall comply with the following required.
- In order to properly apply the specifications herein to achieve the required accuracy the land surveyor must first classify the survey relative to the "Class of Survey" listed in Table 1. The land surveyor shall then apply at least the minimum specifications as listed in the appropriate column in Table 2. An error of measurement which is less than 0.03 feet between sequential monuments shall not by itself constitute a material discrepancy in any class of survey.
- The significance of a discrepancy between the angular and lineal calls of record versus that resulting from the use of these specifications may only be determined from an analysis predicted on the law of random error propagation. If such a material discrepancy is found to exist, appropriate action as outlined in these standards of practice shall be applied by the land surveyor.
TABLE NO. 1
Class A. Urban Surveys:
Surveys of land lying within or adjoining a city or town. This would also include the surveys of commercial and industrial properties, condominiums, townhouses, apartments, and other multi-unit developments, regardless of geographic location.
Class B. Suburban Surveys:
Surveys of land lying outside urban areas. This land is used almost exclusively for single family residential use or residential subdivisions.
Class C. Rural Surveys:
Surveys of land such as farms and other undeveloped land outside the suburban areas which may have a potential for future development.
Class D. Mountain and Marshland Surveys:
Surveys of land which normally lies in remote areas with difficult terrain and which usually has limited potential for development.
TABLES 1 AND 2 Extracted from "Minimum Standard Detail Requirements for ALTA/ACSM Land Title Surveys as adopted by American Land Title Association and American Congress on Surveying & Mapping," 1986.
|ADOT||ARIZONA DEPARTMENT OF TRANSPORTATION|
|AHD||ARIZONA HIGHWAY DEPARTMENT|
|BLM||BUREAU OF LAND MANAGEMENT|
|B.O.R.||BUREAU OF RECLAMATION|
|B/C||BACK OF CURB|
|C/L||CENTER LINE OF ROAD|
|CHNG||CHANGED INFORMATION CODE|
|COP||CITY OF PHOENIX|
|COS||CITY OF SCOTTSDALE|
|COT||CITY OF TEMPE|
|E.P.||EDGE OF PAVEMENT|
|E.S.||EAST SIDE ( PREFIX DETERMINES POLAR DIRECTION)|
|G.L.O.||GENERAL LAND OFFICE SURVEY|
|HUNS,HUNSKR,H&A||HUNSAKER & ASSOC. DESCRIPTION|
|ID/OD||INSIDE DIAMETER/OUTSIDE DIAMETER|
|MCED||MARICOPA COUNTY ENGINEERING DEPARTMENT|
|MCHD||MARICOPA COUNTY HIGHWAY DEPARTMENT|
|NS||NOT SHOT-NO ELEVATION|
|SRPMIC||SALT RIVER PIMA MARICOPA INDIAN COMMUNITY|
|U.S.C.&G.S.||UNITED STATES COAST & GEODETIC SURVEY|
Data Column Explanation
- STA.NO. IDENTIFICATION ASSIGNED BY H&A
- EAST/WEST ALIGN STREET HEADING EAST/WEST
- NORTH/SOUTH ALIGN STREET HEADING NORTH/SOUTH
- MONUMENT DESC MONUMENT MARKINGS OR PHYSICAL LOCATION
- FOUND BY POSITION DETERMINED/FOUND OR RECORDED FOR COS.
- SEC SECTION NUMBER AS DEFINED BY BLM
- COR CORNER POSITION OF SECTION AS DEFINED BY BLM 1
- TN/RN TOWNSHIP "NORTH or SOUTH" AND RANGE "EAST or WEST" AS DEFINED BY BLM1
- ENGLISH (CITY GRID) IN INTERNATIONAL FEET
- METRIC (CITY GRID) IN SI METER UNITS
- COS DATE DATE CITY FIELD SURVEY PERFORMED
- CHNG FOR FUTURE REVISION
- OLD 29 PREVIOUSLY PUBLISHED CITY VERTICAL DATUM
- OLD DESC PREVIOUSLY PUBLISHED DESCRIPTIONS (CHANGED DUE TO CONSTRUCTION, DISTURBANCE OR ACTUAL REPLACEMENT OF MONUMENT)
- STA.NO. IDENTIFICATION ASSIGNED BY H
B) EASTING "X" COORDINATES (DEPARTURES)
C) NEW 29 "Z" COORDINATES (VERTICAL) VALUES NGVD29
D) NAVD88 "Z" COORDINATES (VERTICAL) VALUES NAVD88
B) EASTING "X" COORDINATES (DEPARTURES)
C) NEW 29 "Z" COORDINATES (VERTICAL) PER NGVD29
D) NAVD88 "Z" COORDINATES (VERTICAL) PER NAVD88