DPC units are designed to be installed directly on a stable surface. Good quality soil fill should be used to build up to a non-flooding elevation. A gravel, crushed concrete, or caliche cap should be considered to stabilize the surface.
The skid should be relatively level to insure proper operation: Two (2) inches maximum out of level along the long axis of the skid, and one (1) inch across the width of the skid. Do not allow the skid to be twisted by uneven support. This may put the equipment and piping in a bind and create undue stress on pressure retaining components. The greatest weight is under the heat exchanger support beams, and therefore the most benefit will be obtained by supporting these beams from the pad.