Field exploration elevation - how do you obtain it? 1

[dirt-nerd]

For more important projects (e.g., bridges, retaining walls, culverts, etc.), I require my client's surveyor to go out and survey my borings. However, we do not have that luxury on smaller, less elevation critical projects (e.g., mass grading, small buildings, etc.).

I would still like accurate location & elevation data.

Short of getting lat/long from phone or handheld personal GPS and plopping our location on a contour map and estimating elevation, is there a better way of obtaining relatively accurate x/y coordinates and elevation? How do you estimate x/y/z coordinates of explorations?

I'm wanting within ~1-2ft in all directions. I'd like to have something easy to use/process and < $2k. I don't want to tip into the survey world but rather just have accurate x/y/z coordinates.

 

[LittleInch]

How much money do you want to spend?

A decent survey std GPS comes in around $1-2,000.

A decent handheld prob half that, but then your accuracy will decrease, but still maybe within the 1-2 ft / 0.5m with elevation more like 1-2m.

GPS is an incredible tool and not sure why you're trying to go back a few decades....

Even Google Earth would probably do you if you want to be within 3-5m x,y and maybe 3m Z.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[MTNClimber]

Does your state have a free RTK network? You can get a decent GIS-grade GPS unit for accurate x and y for $500 (Trimble Catalyst DA2 Receiver Kit). If you want accurate elevations too you can use one of the Emlid products. The Reach RX is only $2,800 with a pole. If your state doesn't have a free RTK network, you would have to purchase one. Point One has a good NTRIP network.

 

[TigerGuy]

In my experience, elevation information on boring logs is priceless. I can't say everybody I have encountered views it the same.

If you perform exploration, and many years later, after massive earthwork takes place, a question arises about expanding the project, your boring location and elevation makes it quite simple to move forward.

 

[ABTSGeoScience]

I usually use a combination of 2 or 3 apps on my iphone and compare the elevation results and see if they tend to merge. Then when I get back to the office look on Google Earth and/or USGS maps to see if I'm in the ballpark. The apps I use are called; GAIA GPS, My Altitude, and Altimeter+. They generally tend to be pretty close to one another. I also always include a bullet in my reports that I did not have site specific topographic information and that I used a hand-held GPS with an accuracy of about 15 ft (+/-) and that they not represent that actual elevations on the site.

 

[dirt-nerd]

I agree @TigerGuy. Hence why I'd like to get accurate elevation and location data for all projects.

@LittleInch, I'm hoping to get more accurate than +/- 3-6 feet in elevation. In the geotech world, that can mean fairly significant change. Do you have any recommendations on handheld GPS to get +/- 1-2ft in elevation and x/y coordinates or do those simply not exist? I'm hoping for something < $2k but willing to go higher if it's worth it.

@MTNClimber, I am not sure if we do or do not. I am in Nevada. We need a device that is fairly user friendly with some training for our geotech folks to be capable of collecting the data during field exploration and result in usable x / y / z coordinates within 1-2ft. Is the Reach RX user friendly and is that the only device I may need?

 

[MTNClimber]

Pretty much all survey-grade rovers are easy to use once they are set up. Someone unfamiliar with the process may need some help initially setting it up, but that’s what the distributor is for. Search for Emlid videos on YouTube and see if you’re interested in them. They also have the new RS3 that has tilt compensation, which eliminates the need to plumb the rod, which may give you peace of mind if you have a lot of users in the company.

 

[geotechguy1]

We used to use trimble GPS...sometimes you can get a used one for 4-5k. I think you will probably struggle to get something with good elevation accuracy for under 2k although maybe things have changed.

 

[TigerGuy]

Some drill crews carry a basic level and rod set up, then reference some easily identifiable benchmark at the site (manhole, fire hydrant, building corner, etc.) That doesn't always work when you are busting open a new area.