Finding a level over long distances

[slowworm]

I need to find a level over 200m. Over a shorter distance I've used a hose and water although that wasn't that reliable. I've also used a laser level but there area I need to do this is wooded so a laser not much use.

Do any of the GPS devices come up with an accurate height above sea level? I need something within say 50cm. I had thought about a mobile phone app but there is no signal in that location.

Any other ideas?

 

[ESpy]

Theodolite.

 

[TLM]

Depends on your accuracy requirement. Yes, high precision GPS gives your altitude within a few mm but that is relative to the geoid in use. For good results it needs a clear signal so woodland is bad.

Actually the definition of "level" is not quite clear cut.

A theodolite gives a tangent to that point so at 200m it is not quite a tangent any more.

A water hose gives equipotentials for gravity, if no air bubbles it is quite accurate.

 

[Broch]

My Olympus TG5 camera, fitted with GPS, show the altitude but only to the nearest metre.

 

[Toddy]

Theodolite, and trig works.....and an accurate distance measure. They used to use chains, but archaeologists just used tapes.

 

[Pattree]

Agree - theodolite or simple Dumpy level.

The ancients did it with T squares and spirit level.

There exists a simple hand held level as well: a little sighting tube fitted with a spirit level and a mirror that brought the bubble in line with the cross wires. We used them for putting in drainage ditches in the Forestry Commission. They are probably “collectibles” by now but they must be about. You’d still need a tape/chain, at least three sighting poles, a good compass and a good mate.

EDIT TO ADD
They seem to all be in America but if you eBay “Hand held sighting level you will get an idea of what they are.

 

[Pattree]

Just connected my two brain cells.

If you are using the survey method your laser level will work just the same if not better than a sighting level or a theodolite that you’re not used to. (Don’t use a theodolite anyway unless that’s what you have available. Use a “Dumpy”. It doesn’t complicate things with declination (vertical measurement) it just sets up a horizontal, level sight plane and you can wander about with your sighting rods but you can do that with your laser anyway.

If it’s important and critical then hire a surveyor.

I’m an old fart and I don’t know what your project is but I don’t think I’d trust a phone app to the degree of accuracy that you are looking for.

 

[TeeDee]

I need to find a level over 200m. Over a shorter distance I've used a hose and water although that wasn't that reliable. I've also used a laser level but there area I need to do this is wooded so a laser not much use.

Do any of the GPS devices come up with an accurate height above sea level? I need something within say 50cm. I had thought about a mobile phone app but there is no signal in that location.

Any other ideas?

I haven't gotten any smart answers - but would be interested in why you are doing it?

 

[Mesquite]

If the site is wooded as you said then a theodolite or dumpy lever won't be much use either as they rely on line of site, same as a laser level.

Personally I'd use a laser level with a ranging pole and just keep moving the level to the pole in steps until you reach the point you want to establish the height at.

You might have to zig zag through the woods a bit but it's not impossible to do.

 

[Toddy]

Thing is you can hire theodolites/ dumpies, but you don't really get things like Plane tables these days.
It's old school, but it works.
If you can make certain that your table is level, then it might be the easiest method.

Plane table - Wikipedia

en.wikipedia.org

 

[Pattree]

This crossed with @Mesquite but budgeted if I’ll delete it all now
You may be getting a bit too much advice right now but.

Sorry if the what follows is known to you already. I also have an excellent egg sucking technique if you’re interested

The area is wooded so whatever you use you will have to work in steps. Map out a series of rough straight lines that take the closest route to your project. Each end point to give a straight line view to the next.
if you are going to fell trees then obviously do that first to get the straightest line. If not, work around them as @Mesquite suggests.
Start with a datum point, preferably in the ground. It doesn’t have to be an OS datum and it doesn’t matter what it’s actual height is as long as its position is permanent for the duration of the project and is recorded. You could just drive in a post to nearly ground level and use that. Work the longest useful straight line that is available, one that takes you to the next straight line. Establish your new level and sight up the next one until you reach your end point. We did this around the perimeter of a forest plantation in Delamere Forest - nearer to 2KM than 200M and in a circle.
I’ve also brought a level from the roadside to half way down Belle View Park in Newport (Gwent) full of ornamental trees.
It takes time so give yourself time.

 

[slowworm]

Thanks for the replies. I did think a theodolite would suffer the same problems as a laser level.

Without spending large amounts of money on a fancy GPS device the best I can come up with is as has been suggested, use the laser level in stages (probably just chalk the level on the trees as I go).

I'm trying to work out if there's a better solution to our water supply. It's a spring that is captured in a holding tank then pumped to our house tank. The supply pipe is long and may need to be a special pipe so I was considering adding a 2nd holding tank nearer the house which is filled by gravity - hence needing to work out the level.

 

[Dogoak]

I’d be interested in why you need the level, and to that accuracy?

Just use alkathene pipe.
I had to replace my spring water pipe at my old place. 600m of alkathene, from holding tank across a moor down to the house, 1m deep! a gravity system, so no hassle with pumps

 

[slowworm]

I’d be interested in why you need the level, and to that accuracy?

The water is pumped up using a ram pump so fall is crucial to it working. As for accuracy a nearer holding tank would need to be built into a slope so I'd like a reasonable idea of where it could go and if that leaves a decent fall for the ram pump.

 

[slowworm]

My Olympus TG5 camera, fitted with GPS, show the altitude but only to the nearest metre.

I'm wondering if a drone would also show height and if it would reliably fly level? I'd guess a cheapie one wouldn't.

 

[gg012]

I'm wondering if a drone would also show height and if it would reliably fly level? I'd guess a cheapie one wouldn't.

Not to any decent sort of accuracy, no. A dumpy level is your best bet, unless you can find one of those optical levels mentioned above.

Sent from underground

 

[Pattree]

I like your idea of laser and chalk. It’s what you’ve got and it’s worth a first try at least. Have you got a height adjustable tripod like those for a camera that will take your laser level?

I can’t get my head around your set up, not that is any of my business

The spring is below your home tank and at a distance.
The ram pump is decanting its drive water/main flow further on down below the spring.
It is pushing its pressurised/delivery water up to you holding tank. I’m just wondering where the level bit comes in -
Don’t waste electrons explaining this unless you really want to. I’m a bit hard-of-thinking these days.

 

[slowworm]

The spring is about 10m lower than my house but about 200m away. If the pump is next to the spring the delivery pipe needs to be 200m long. If I have a holding tank nearer the house then the delivery pipe can be much shorter. If the ram pump fails I could also use an electric pump which would be easier with about 15m of cable and pipe rather than 200m.