CAD topo maps?

I was wondering if there are topographical maps in CAD that show an
elevation change of a foot for an area 1/4 mile by 1/4 mile. I found some
30 meter maps from topodepot.com but that is too big. If not one foot, what
is the smallest elevation increment that is available? Thanks.
Reply to
Jerry
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Thanks for the info. The company I work for is expanding the building by adding a big warehouse. I have laid out all of the information such as square footages of new roads and parking but my mangaer wants to see if I can find out how much earth will have to be moved. All this info will be turned over to the contract company who is going to be handling the project. Although they will most likely get their own information as to how much earth will be moved and such I am basically getting it before hand to help with the cost esimates so the bosses will know if their is enough money in their budget to do what they want to do.
Reply to
Jerry
The USGS type information IS NOT good enough for that, FWIW. The TopoDepot stuff would be suspect at best for that purpose, as well.
I'd suggest getting a surveyor. If you explain the situation, and the site is generally open, it shouldn't cost very much. If that's out of the question, you'll have to get someone with a level and do a quick grid-type survey to get elevations worth using to get volume calculations. If you need a more detailed description, let me know.
In any event, BE CAREFUL with how you get your number for earthwork. There are MANY issues involved here that can DRASTICALLY effect the number, not the least of which is the accuracy of your 'existing ground' information.
Is it safe to assume that your ground is relatively flat? You mentioned a building, parking area, road, etc. This is the type of work I do, and frankly, from what you're describing, you could be asking for alot of trouble, dabbling in earthwork calculations.
Reply to
TomD
Thanks again. Yes, the area is fairly flat, change of elevation of about 3 feet across the area I am working on. We actually have the original site map with the building on it that has the elevation to the tenth of a foot but it is a lot of information and the print is twenty years old print so I will obviously have to tranfer the information to CAD. Since all we need for now is a rough estimate I will be generating a 3D model of a small area ( 700ft x 500ft ) of land and subtracting the volume from the new warehouse to get an estimate of how much earth needs to be moved. Since the land is mostly flat I think the numbers I get from the solid model will be fairly accurate to the volume of earth needed to be moved. I don't do this all of the time like you but I think this way should get the results I am looking for.
Reply to
Jerry
Sounds reasonable to me. Given a change of only 3', you could probably eyeball an average depth and multiply by your areas. Just make sure your boss won't hold you to the volumes. ;)
Good luck to you.
Reply to
TomD

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