My firm does a lot of small projects that undergo a pretty high level of scrutiny. These small projects do not bring in enough money for an engineer to spend a lot of time with the project. I have heard a number of people tell me Civil 3D is overkill and too complicated for for the small projects. Projects so small that you may not even think about an FG surface unless you needed profiles, sections or soil movement numbers.
We have a number of project like these. Yes small enough not to warrant any FG surface. Heresy you say? Off with his head!? Well consider a proposed rectangular pool going into someone’s back yard at existing grade. Would you grade this out if the final plan sheet would show 1 or 2 proposed contour lines, you could do the volume calc in your head (pool area time 5′ avg depth) and you could label the FG elevations with one text string (Tip: Use a Civil 3D General Note Label instead) copied to the 4 corner locations of the pool patio? My firm needs to get as much profit from these small projects as we can and we try to stick with the KISS (Keep it Simple Stupid) principle. With this all said I am going to provide a multi-post article that outlines some of the grading practices we use on the smaller projects to minimize our time investment.
Post 1. Clearing
Many of our projects involve clearing trees for a small stretches of new sewers or pressure conduits, clearing of paved areas or demolishing buildings. These small projects are not highly detailed and are typically labeled, “Clear & restore to existing grade”. They also do not require resurfacing materials to be itemized. When these projects pop up, we often need a fast FG surface for profiles & sections. How do we get the FG surface & project complete without a great time investment, a corridor or gradings? Find out after the jump.
The fastest FG surface we create is with a simple clearing area that typically has no EG breaklines representing large grade breaks within the grading/disturbance area. As an example we may have a tree clearing or sewer replacement under a road as I mentioned above. In the image below I am depicting both. A small sewer replacement & and an extension into a wooded area. In both cases I need to restore existing grades. I also need a plan & profile sheet for each sewer branch depicting the limit of clearing & the sewers for engineering review.
With projects like this I am able to create my proposed pipe network before I having an FG surface since we are restoring existing grade and EG is FG. I draft the pipes and the structures are linked to the EG (they can be quickly changed later in Panorama if needed). Inverts are adjusted & I more to creating an FG surface.
I start the FG by forming a 2d polyline for the limit of disturbance. Here I centered the pipes in a polyline to represent a 10’ wide trench. I select the EG surface, copy it with the AutoCAD copy command and rename the surface appropriately. Apply the limit of disturbance/grading as a boundary & the FG surface is done. The polyline is retained for a Civil 3D Line label to display the area disturbed to the soil conservation district.
What if we were demolishing a building, removing curb or walls? These are the areas where EG breaklines typically exist within the grading area as shown below.
If we take a building to be demolished as an example, draw a feature line around the building (TIP: use NCOPY on your Xref’d base maps if 2d linework exists) and assign elevations from the EG surface. I create a new surface and add that feature line to it. The building is filled. FG is complete. Similar methods can be employed for curbs & walls. A bit more data may be required with wider clearing areas. When curbs are involved, you may want to explore using a bottom of curb border on a copy of the EG & raise the surface the curb height.
This information may not be new and simply creating the FG surfaces alone may not be a tremendous time saver over LDD. But start adding time saved with Civil 3D pipe networks, alignments & profiles from those pipes all drawn automatically and in one process with the Profile Creation Wizard, Civil 3D labels & this little project took less than 20 minutes of engineering time with all of the plan labels I would need.
We can profit off of that.