Plateaus in a process plant site 1

[Fachoalto]

Hi, gentlemen,

My company is going to set up a big process plant in Brazil. The selected site has a total area of 20 km². The plant layout covers roughly 70% of this area. Natural topography has elevations between 15 meters and 50 meters. The company has recently contracted basic and detailed earthwork projects, including drainage. As an input to these projects, my colleagues have defined plateaus, at different levels, with areas ranging from 0.5 km² to 4 km².
My questions are:
Is there any advantage in having horizontal plateaus of so huge dimensions?
Wouldn't it be better if we allowed some declivity (ok, below a specified maximum) for the final grading (i.e., instead of horizontal plateaus, they would have a slight declivity)?
Wouldn't it be better if the final grading followed natural topography (i.e. we would just specify the maximum declivity allowed in the graded surface)?

Thanks in advance for your opinions.

 

[cntw1953]

In planning stage for large scale project, it is beneficial to subdivide the land into parcels for ease of communication and for later handling (division of work among groups). To me, there are two aspects need to be considered carefully - overall dranage plan for entire project area and approxate balance in excavation and borrowing. Keep in mind that the initial plan will likely undergo several changes, the final may not look like the original, Site planning is usually handled by very knowledgeable/experienced persons, talk to them, and understand and learn from their's experiences.

 

[Fachoalto]

cntw1953,

The problem with the knowledgeable/experienced persons is that, in general, they can't produce better answers than "It has always been done like that". Believe me that I am always trying to understand from their experiences. The problem is that they usually can´t answer to questions that go beyond common practice.

Also, I always keep in my mind that, as you say, initial plan will likely undergo several changes. For this reason, I think that site preparation should not be strongly dependant of the structures that are going to be built. On the contrary, structures themselves should be designed to conform to the site final topography.

 

[cntw1953]

The big accomplished companies usually have well delevoped ways to handle things based on past experiences. After a while, the reasoning falls victim to project delivery, which is to follow the routine without spend time to re-invent the wheel. Also bear in mind, the best engineer may not be the best communicator. You may need to dig out yourself by work through this project.

 

[bimr]

The ideal situation would be a level surface for the project.

I would have to say that in a typical processing plant, there will be some areas such as in a large assembly building or a steel mill where it is necessary and required to have the entire building at the same grade.

You would also want adjacent buildings where products are continuously transferred back and forth to be situated at more or less the same level.

However, the answer to your question depends on what type of processing plant is being planned.

The area that you are working with seems to be very large. It is difficult to envisage a requirement for such a large level plant site.

 

[cntw1953]

There is 25m elevation differential in 25km² land, without knowing site topography, it is not possible to come up a good recommendation.

 

[ishvaaag]

Just for comparison here in Zaragoza, Spain, there has been an 8 km2 industrial development where the lots between main transverse streets are about 0.75 km2. I think of it mainly as a way of putting in some general order, in this case main parcels along a spine. You can see it in google-earth, a white area at the SE of the town, destined to process junkyard and every kind of recovery of products that have ended their useful life. Haven't gone there yet, it seems to be very small slope or flat, anyway continuous enough to allow the scheme you can see.

 

[Fachoalto]

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cntw1953,

The actual figures are: 35 meters of elevation differential, in 20 km².

But the main question is: What kind of problems we would incur into, if we decide to allow a slope of 1% or 2% along any direction? Up to the moment, I can't visualize any. Most of the buildings or facilities won´t lie directly over finished grade. There will always be a slab under the first level. Take the parking lots, for instance. They are going to be graded flat and horizontal. Don't you agree with me that this doesn't make any sense?

 

[cntw1953]

Yes, first grade mistake.

I guess this (level plan) is initial rough grading. Each pracel will ultimately having slopes after fine tuning the layout of plants, roads, .. etc, within it. I agree with 1% - 2% final grade to allow surface runoff.