Our Skim Pile Drain Caisson treats deck drains for strictly regulated applications w/ an Intermittent Flow utilizing multiple baffles and oil risers, while separating oil from water and sand.

Skim Pile Cutaway


SKIM PILE ≥50 MICRON (Intermittent Flow)

Open and Closed Drains intermittently enter the caisson. As the liquid flows down the caisson, it enters a baffled section (typically starting at EL (-) 20’-0’ LAT). The baffles are spaced equivalent to the caisson diameter and this section is where the oil/water separation occurs. There are many advantages to the tightly spaced baffles:

The ESI Skim Pile Cleans sand as it tumbles and rolls down the baffles, and has a greater surface area for oil to collect and coalesce.

1. Allows a shorter distance for free oil droplets to rise.

2. Creates a quiescent zone under each baffle allowing optimal conditions for oil/water separation.

3. Greater surface area for oil to collect and coalesce.

4. Cleans sand as it tumbles and rolls down the baffles.

Meanwhile, oil risers prevent the remixing of coalesced oil with the downward flow of water. Based on an intermittent flow of 2”/hr. rainfall for 20 minutes, ESI guarantees the removal of all free oil larger than 50 microns.

SKIM PILE ≥500 MICRON (Continuous Flow)

If the specification requires a continuous flow, then the caisson diameter must increase. This allows the larger oil droplets (≥500 micron) to rise faster than the exiting velocity. The baffles are spaced equal to the internal diameter and extend past the centerline for more surface area. Oil risers are used to prevent re-mixing oil with the water.