Use of State Plane Coordinates - Public Resources Code

[Sunburned_Surveyor]

I've got a couple question sabout the use of State Plane Coordinates on a Record of Survey, and I was hoping you guys might be able to help me out with the answer.

Section 8801 to Section 8819 of the California Public Resources code provides code governing the use of State Plane Coordinates.

Section 8813.1 is the section that I'm particularly interested in. It states, in part: "After December 31, 2005, any survey that uses or establishes a CCS83 value or values shall meet all of the following requirements:..."

It then lists some of the requirements. Here is my first question:

If you have a Record of Survey that uses a basis of bearing based on CCS83, but that does not show CCS83 coordinate values, must you still meet the requirements of this section?

The requirements in this section basically state that your survey must be reference to one or more stations that are a CSRN station or meet the requirements to be a CSRN station. I have looked online, but I have been unable to find these requirements. Here is my second question:

How do I find out the requirements for a station to be included in the CSRN, or determine if a control point used in part of my survey meets the requirements for inclusion in the CSRN and thus fulfills the requirements os Section 8813.1 of the public resources code?

It is also interesting to note that Section 8813 of the California Public Resources code, which doesn't appear to apply after January 1, 2006, requires ties to at least two horizontal reference stations, while Section 8813.1, which applies after January 1, 20006, requires ties to "one or more" horizontal reference stations.

Is there a reason for this change, or was a mistake made in the drafting of the 8813.1 section?

One more thing. :]

Section 8813.3 states that: "After December 31, 2005, when a survey that uses or establishes a CCS83 value or values is shown on any document, the station or stations to which the CCS83 value or values are references and connected and the CCS83 value or values and the published or stated accuracy or accuracies of that reference station or stations shall be shown also on the document."

Does the reference to "value or values" in this section mean "coordinates"? Could I have a basis of bearing on a Record of Survey that is based on two (2) CCS83 points, indicate this by identifying the name of the control points, but not show the coordinate values of the points?

Does use of a "grid" bearing based on CCS83 mean I have to meet the requirements of the sections I've talked about here?

Thanks in advance for the help.

The Sunburned Surveyor

[Bob Hart]

This is not as simple as you may think, but it only matters if you are claiming a specific accuracy. Good Luck, and I hope Tom Taylor is available to comment.

[Steve Martin]

If you are going to use the California Coordinate system for a Basis of Bearings, then you have to tie to one or more stations as indicated in 8813.1

I personally think the "one" in one or more is a mistake, but it was changed to accommodate RTK users who use only a single base station. When you do that, the "Basis of Bearings" really comes from the broadcast orbits of the GPS constellation (WGS84 related datum) and not from the NAD83 Datum. But some operate on the "close enough" principle.

By using the term value, I believe the intent is to show either a CCS83 coordinate or a Geodetic NAD83 position. It is just good practice to show the "value" a survey is based upon right on the face of the map rather than have future readers wonder what was used.

So yes, grid bearing does mean meeting the requirements of the PRC.

[pls7809]

I was actually just dealing with this issue regarding a survey in Ventura County I was working on.

A CSRN eligible station is defined in PRC 8856. I had to look it up as well.

Basically 5 criteria need to be met for a station to qualify as CSRN stations: (I think 8013.1 should tell you CSRN as defined by 8856, or something similar)

1 - Be referenced to NAD83
2 - determined by GPS methods
3 - published by NGS or CSRC
4 - a NGS or CSRC published network accuracy of 2 cm or better as defined by FGDC or a NGS or CSRC published accuracy of first order or better as defined by FGCS.
5 - a NGS or CSRC published horizontal velocity or a horizontal velocity that can be determined using procedures and values published by NGS or CSRC.

I take values for stations to mean coordinates. I personally always show the Coordinates of the NGS points I'm tying to, the bearing between them and the published horizontal order of the points.

[Sunburned_Surveyor]

Thanks for all of the responses gentlemen.

Thanks especially to Ryan, who provided the reference for Section 8856, which is what I really needed.

I also called to clarify this with my County Surveyor. He said that he would like to see the two control monuments used to establish the grid basis of bearing with at least one tie line back to the project site. He also said that I would not need to show the coordinates for the control points if state plane coordinates are not used elsewhere on the map.

It would be nice if we could clarify whether or not a basis of bearing that is a grid bearing triggers the requirements for use of state plane coordinates listed in the PRC. Perhaps that could be suggested to our legislative committee?

Thanks again for the help guys.

The Sunburned Surveyor

[akw]

The City of San Diego has standards and procedures for this. This will be part of the City's Subdivision Manual that is near completion and will be published. Send me an email and ask for the coordinate ties: awake@sandiego.gov

[dmi]

The question you have asked really has nothing to do with the PRC. What you are really asking or ought to be asking is WHAT DATA IS TO BE INCLUDED ON THE MAP OF MY SURVEY SO THAT OTHERS WILL FIND IT USABLE AND BE ABLE TO RETRACE MY SURVEY?

If there is insufficient data on the map, how can anyone compute convergence, scale factor, figure out where you are in the Zone, what the epoch of the control is or the epoch of the survey is? Why bother with a grid basis of bearing at all, just find 2 mons and call it North for the purpose of your survey.

[PLS7393]

Originally Posted by Sunburned_Surveyor

It would be nice if we could clarify whether or not a basis of bearing that is a grid bearing triggers the requirements for use of state plane coordinates listed in the PRC. Perhaps that could be suggested to our legislative committee?

You bring up a good question, the clarification of basis of bearing?

I've done some research looking for a good definiton of basis of bearing, but haven't found one. I think we all assume (or should) that a basis of bearing is two known (found) monuments. I've seen maps which call a deed line their basis of bearing, but they don't even hold the found corners shown??? Please see my new thread posted instead of threadjacking Sunburned's original question.

[E_Page]

If you are claiming CCS83-Zone Whatever, you are implying that all of the map values shown are based on that datum.

Are you also stating a CSF to convert grid to ground or vice versa and also stating whether the distances shown are ground or grid?

If you are simply using the monuments and their stated CCS83 bearing as your bearing base, but not actually running the project in CCS83, you should not claim CCS83 as the Basis of Bearings, but instead state that the bearings are based on monument X and monument Y with the bearing from X to Y being DD MM SS. No mention of CCS83.

If you are running your project in CCS83, ignore that last paragraph.

[Peter Ehlert]

as a minimum (in all cases) you should state that the bearings are based on monument X and monument Y with the bearing from X to Y being DD MM SS.
if the Mons are SPC then you should ALSO state the coordinates used on each monument and the source and datum (never leave out the epoch).
If you ate using topo quality (RTK) then you should say so.

[Steve Martin]

While I think Evan's posts on this forum are usually well thought out and right on point, I disagree with the statement:

"If you are simply using the monuments and their stated CCS83 bearing as your bearing base, but not actually running the project in CCS83, you should not claim CCS83 as the Basis of Bearings, but instead state that the bearings are based on monument X and monument Y with the bearing from X to Y being DD MM SS. No mention of CCS83."

An inverse of California Coordinate System (CCS83) coordinates yeilds a CCS83 bearing. Otherwise it is just an assumed bearing from assumed coordinates. The County Engineer's Association Record of Survey guide Ryan Versteeg refers to in the "Basis of Bearing?" thread,
limits acceptable basis of bearings to a) a record line, b) a solar observation, c) the California Coordinate system, to paraphrase the document. http://www.ocgeomatics.com/pdf/record_of_Survey_and_Corner_Record_Guidelines.pdf
There is no mention of assumed basis of bearings being acceptable, in fact I believe the intent is to prohibit an assumed basis of bearings.

If it walks like a Duck, talks like a Duck and is a Duck, I think you have to call it a Duck. Calling a CCS83 bearing a random bearing leaves the reader of your map wondering where the bearing came from and does not meet the statutory requirement for establishing a basis of bearings in my County.

It would be perfectly acceptable to add a statement "This survey is based up the California Coordinate System bearing between monument x and monument y being DD MM SS, however distances shown are ground distances and this survey is not projected to the CCS83 grid".

Make it clear on your map what you used and what you did. Use the California Corrdinate System, it is a great tool to account for geodetic corrections and to control error on a survey. Include the coordinates used, datum, epoch, combined grid factor and convergence angle for CCS83 control points to help future users of your map.

[E_Page]

I like that solution even better, Steve. My concern was that a BoB note that calls CCS83 when only the initial bearing was from CCS83 but the rest of the job not run as such would still give the impression that all info on the drawing was CCS83.

[Steve Martin]

We use the California Coordinate System here at the County of San Diego. Our maps will be on the grid and we are carefull to so note. We also include a statement the "Quoted bearings and distances may or may not be in terms of the California Coordinate System" to let the reader know that there may be some grid verses ground differences in record bearings and distances.

Mixing and matching between the California Coordinate system and ground or hybrid scaled to ground coordinate systems is a problem in our industry so documenting with statements how the survey and map were prepared is vital.