Flat rough grade is always better.  
If there are to be several plateau elevations, they should be set on a material balancing method if possible, the amount cut, should equal the amount of fill + swell factor as nearly as possible.  The fill areas should be in areas of the plant that will not require heavy foundations.  Heavy foundation areas should be placed in cut areas if possible to minimize preconsolidation times.  Foundations on fill will require preloading for a relatively long time before appropriate preconsolidation conditions are reached thereby allowing foundations to be placed in soil that will not settle inappropriately.  Talk to your geotechnical consultant and get their recommendatins based on your predicted loadings as to where those equipment items will be best supported by the site's underlying soils.
 

**********************
"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/

BigInch,

Thank you for your reply, but the primary reason for considering landform grading is exactly the search for minimum earthwork. It is not just a question of balancing cut and fill, but also of minimizing their amount. With some exceptions, I don't think that process facilities will lie over direct foundations (of course I can be wrong; this is my first refinery). Googling in the Internet, I´ve come to know a work by Horst J. Schor and Donald H. Grayn (an ASCE publication) whose abstract follows:

"Transportation corridors and residential developments in steep terrain both require that some grading be carried out to accommodate roadways and building sites. The manner in which this grading is planned and executed and the nature of the resulting topography or landforms that are created affect not only the visual or aesthetic impact of the development but also the long-term stability of the slopes and effectiveness of landscaping and revegetation efforts. Conventionally graded slopes can be characterized by essentially planar slope surfaces with constant gradients. Most slopes in nature, however, consist of complex landforms covered by vegetation that grows in patterns that are adjusted to hillside hydrogeology. Analysis of slope-evolution models reveals that a planar slope in many cases is not an equilibrium configuration. Landform-graded slopes on the other hand mimic stable natural slopes and are characterized by a variety of shapes, including convex and concave forms. Downslope drains either follow natural drop lines in the slope or are hidden from view in swale-and-berm combinations. Landscaping plants are placed in patterns that occur in nature as opposed to random or artificial configurations. The relatively small increase in the costs of engineering and design for landform grading are more than offset by improved visual and aesthetic impact, quicker regulatory approval, decreased hillside maintenance and sediment removal costs, and increased marketability and public acceptance."

©1995 American Society of Civil Engineers

Your main process facilities will have very large foundations with very heavy dead loads and high overturning moments from wind loads on those columns.  

The reference you have found seems to be mainly devoted to aesthetics.  All very well and good, but of no to little importance in the typical refinery.

A slope of even 1/4" per ft when sustained over those large runs will amount to a significant difference in tops of concrete and grade from one side of a unit to another, or do you plan on having different toc elevations?  That wouldn't be good.

Another factor you may run into with many elevations is trying to move large (LONG) vessels and towers up/down steep slopes and level areas when constructing.  Very bad.

You seem to be considering cut and fill balance, but letting drainage control the configuration, rather than the needs for basically horizontal piping.  What doesn't run downhill, you have to pump uphill.

Its not my first refinery and I can tell you, you will regret not having it as flat as possible when you try to construct.  That said, locate refinery supply tanks high up, but not above ship discharge pumping heads.  Locate finished product tanks low.  Locate everything else in the middle elevations.  Pick large stable areas for tanks.  They of all creatures do not like differential settlements.  High vapor pressure products (gasoline over 100F, butanes, light hc) go to the higher elevations when convenient.  

Good luck.

**********************
"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/

what about use the elevation to minimise pumping efforts?
take crude in on top,end products at bottom
 

Sometimes crude and finished products move in and out on ships, so you might want the crude low and the finished products high.

**********************
"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/

BigInch has a point. Geographically, if it is located next to a major waterway, keep the crude low.