Site setup with no Control

First I have some questions. 1.) Do you have a set of plans for the project? 2.) Are the 3 pins shown on the plans? 3.) What are GCM monuments? 4.) Do you have a total station or robot to get better measurements on the 6 GCM's and 3 pins?

If you have no control, the best you can do is make everything relative to itself. You have no idea how you relate to the property or any other adjoining elevations. If that is all you need, your method works. 95% of the time control is needed though and you can't do a site set up without it. 

@landbutcher464mhz yes full cad file and access to property lines, the pins are adjacent to a main road and appear to have been buried by a plow and run over many times. Geodetic control markers or monuments they are a set of control that the government maintains in British Columbia. No just a gnss rover and base

@lurker I don't think no control was the right way of putting it as I can still be geographical accuracte with the government maintained gcm. How would you go about verifying your accuracy if you used government markers to setup your equipment

@ctower I'm not familiar with British Columbia but the government monuments are likely giving you a position relative to the earth. You need to know your position relative to the property and as far as I know neither Canada or the U.S. has cataloged property parcels with coordinates. Therefore you may know where you are in the world by using the government monuments but you still need to know where you are relative to the property that you are building on. Maybe you are building on a 40 acre site and are no where near the boundary lines and there are no easements across the property. Then you in all likelyhood will be at no risk of putting the building in a location that could be costly in the future. However if you are on a typical lot with set backs and easements and you put the building in the wrong place, the mistake can be very expensive. the designed plans can be placed anywhere. Control relative to the property is needed to place the design on the property correctly. This typically is the responsibility of the civil engineer and in most municipalities in the U.S. you can not get a building permit without showing the proposed building relative to the property. Putting it other than in the approved location can be costly. Location being both vertical and horizontal.

Your procedure for establishing coordinates for your base station seem solid.

For me the bigger question would be how to relate the design to the GMCs.  Are the plans on the same coordinate system as the GMCs? 

I for one think it is unprofessional (verging on negligent) not to provide semi-permanent control on design documents including pre-design surveys.  We are paid to provide a foundation for the design and construction of the project.  Withholding the control used in the creation of this foundation is basically defrauding the client.  The only reason I can see for not providing control is to limit one's liability or give them a leg up in pricing layout.  I doubt it does either. 

Here is a guide from the NGS that is worth your time:

UserGuidelinesForSingleBaseRealTimeGNSSPositioningv.3.1APR2014-1.pdf

I suggest setting up base station locations at about 1200m (3/4mile) intervals along your route that are well outside of the construction zone and that have near perfect sky. Better base conditions make for less trouble at the rover. 

And I second the warning that your project coordinate system may not be exactly the same as your government issue "GCM" system. Confirm that.     

@john-putnam  @Norman_Oklayoma yes I believe it's a requirement for design to have the project designed in the correct coordinates relative to the earth, but I do triple check my site based on points established by the survey team who designed the projects to give me the confidence that im correct. I suppose I can use the property pins as the limit as it is included with the cad file and ensure that my site setup and property line are equivalent geographically and I am familiar with that text as one of the guys I learned from recommended it along with one from Jan Van Sickle

Are there any existing conditions that you can locate and relate to the CAD file that you've been provided?  It's always the first thing I do to make sure that the control network wasn't translated somehow.

Your plan sounds good for establishing control.  If you want to tie to the Canadian system, you might try running a couple of your points through their precise point positioning service: https://webapp.csrs-scrs.nrcan-rncan.gc.ca › geod › ppp  to get the Canadian NAD83 position and to be able to compare your position relationships on the two points just to check them.    

***Trigger warner, this is not a helpful comment, please don't read it.

It'd be amazing to have a global system that would allow all surveyors to measure to the same mathematical model of some massive spheroidal object. Maybe add a temporal component too to titillate the geophysicists.  No more worrying about silly little chunks of metal or stone getting jostled or destroyed. Everything would be relative. Surveyors could just setup their receivers and begin working without blowing budgets having to beg ignorant parties for information vital to the success of the project. Oh well, just a sci-fi dream, time to go reshoot a mower- mangled right of way monument or five and hope the magic localization button does me good. Oh wait, there's a manhole lid I can check to, lucky day!

@murphy it's all good I did find my manhole

I would start by running a good static survey over those three marks you do have

Then compare your numbers with the 'official' 

That should tell you whether you can rely on them.

I would also include a known-good local mark or two.

If you really can't make anything fit - pick one and work everything relative to it