How do I create | determine the proposed platform level from NGL | OGL surface?

[kuguzevu]

I have a surface described as OGL, please how would I assume or determine the proposed platform level | design elevation for the surface. Attached is a screenshot of OGL

[Anonymous]

More information needed with regards to "proposed platform level." What are you trying to design? A road, a building pad with parking lot, a landfill? What are your design criteria, such as maximum slope from proposed to existing surfaces? Do you have the horizontal geometry of the "proposed platform" determined? Your question is way too open ended to expect useful answers from here.

[kuguzevu]

Thanks for your response.

Residential units and roads would be on it. Assumed a 2% slope from the proposed to the existing surface. There are many units coming on it. What I want to know is, if I have an existing surface (blank surface) and a building pad is coming on it. Let us take an instance,  a building is coming on that contour lines. How would I go about determining the proposed platform level?

I think the first thing to do is to determine the proposed platform level before grading the building pad. Kindly put me through, thanks.

[Anonymous]

I'm still not clear on what you mean by platform. If you mean the first floor elevation (FFE), we typically put the FFE 1.0 ft above the adjacent finished ground. To model this you would have to use a feature line at FFE, then offset it a minuscule distance outward and lower it 1.0 ft. From this second feature line you would grade your parking lot, sidewalks, etc., until you get to the edge of the improvements. From there you could use grading to match into the existing ground at the desired slope.

If you do not know the FFE to begin with you could guess, create the proposed surface, see what happens when you send the grading into the existing surface, then raise/lower the entire proposed surface ass necessary to better fit exiting conditions. It it have to be handled on a building by building case with grading the parking in between appropriately.

[kuguzevu]

Very helpful, I do not know the FFE (first-floor elevation), I will go with the second option. Please,  do not mind that I am disturbing you with questions. I want to ask this last question regarding the attached JPEGs and PDF.

A proposed level is used for cut and fill after the retaining wall in the Figure below. Let us assume, I want to use the parcel for farming and I want a levelled surface. How would I determine the cut and fill if I do not have a proposed elevation?

Please, check the Jpeg below and I have also attached a PDF. How do you determine the final level for the cut and fill outside the building pad?

[kuguzevu]

what I meant by the platform is the surface, If I want to create another surface as a comparison to the existing ground. just to determine the cut and fill.

If I assume that the surface is flat, I can draw a polyline around the boundary and create a feature line from it. I can assign an elevation to the feature line. How would I determine the mean elevation or actual elevation to use.

I need your advice, thanks.

[kuguzevu]

what I meant by the platform is the surface, If I want to create another surface as a comparison to the existing ground. just to determine the cut and fill.

If I assume that the surface is flat, I can draw a polyline around the boundary and create a feature line from it. I can assign an elevation to the feature line. How would I determine the mean elevation or actual elevation to use

[tcorey]

"How would I determine the mean elevation or actual elevation to use."

Do you mean, if you already have a finished ground surface, how to you obtain its mean elevation? Go to Surface Properties, Statistics tab. Expand General. Mean elevation will be listed last in this section.

[Anonymous]

Oh boy, that is not an easy question to answer. You mentioned grading of the parking lot - there will be slopes and changes in elevation all over. And it is not a simple site. It isn't as simple as creating a feature line with mean elevation. Are you looking for a place to begin? I'm not sure I understand.

If you have created all the grading you need for building pads, pavement, curbs and sidewalks with feature lines or other entities that have valid elevations you can create a new surface and add teh objects as breaklines. Then add that boundary as a border. Then create a feature line that extracts elevations from the new proposed surface and daylight it into existing ground at the desired slope. If you have errors daylighting you can either change the slope or raise/lower the surface.

[kuguzevu]

Thank you for your response. I got the meant elevation, which is 991.545m.

Is it right to assign a building pad to this elevation if I want to grade, assuming I want to do earthwork design-having a finished ground surface and building pad (100sqm)?

Is it possible to assign the contour lines to an elevation of 991.545m (the same elevation) that would be used as a comparison surface?

Another problem that might arise is this, in a steep slope, it would not be proper to a constant design elevation because you might have to retain the soil and the design or proposed elevation varies.

[wfberry]

Let's just be blunt here.  You need to contact someone who knows how to design a project that you have.

Bill

[kuguzevu]

Thank you for your precious time. I know it is not an easy question to answer. I do understand the two-paragraph. Let me say I am looking for a place to start. Assuming I have a finished ground surface and building pad (100sqm)? And the mean elevation is 991.545m. How do I go about it?

[kuguzevu]

Yes, you are very right.  I am into road and stormwater design. I just want to get the concept.

Let me say I am looking for a place to start. Assuming I have a finished ground surface and building pad (100sqm)? And the mean elevation is 991.545m. How do I go about it?

[Anonymous]

If you have a finished surface you should be able to create a feature line around the outside of it and use grading tools to daylight it into the existing surface. If you can post a sample drawing so that we can provide better answers.

[Joe-Bouza]

There is a lot grade subassembly for that.

[kuguzevu]

Thanks, I will do just that

[kuguzevu]

Thanks

[fcernst]

You need to design preliminary profiles for all those internal roads, then do preliminary overlot grading to determine which lots will drain as FHA Type A, B, G or W lots. Then do detailed individual lot grading. 

The required Top of foundation (TOF) elevations to meet Code are calculated and fall out at very end of the process … as a function of the detailed lot grading. 

[kuguzevu]

Thanks

[fcernst]

You need to refer to your contract with the Developer. Some civil engineering  contracts with the Developer will stop at Overlot Grading. Then the Developer sells the lots in their Overlot Grading condition to Builders who are responsible for hiring a Civil Engineer (maybe you) to create a detailed grading plot plan and calculate the required TOF elevation as part of their building permit requirement.