Up until this time, the bottom of cylinders were capped off by welding a flat plate to it.
The accident investigation resulted in a change in the code required construction of the cylinder bottom in 1972. The cylinders, after 1972, were required to have a dished or rounded plate at the bottom, as well a double bottom with a small hole in the secondary bottom to allow a more controlled decent if the primary bottom were to fail.

The double bottom cylinder is one issue. Another concern is the way the cylinders were put into the ground. Up until about 1986, cylinders were buried in the ground without any cathodic protection. In some cases, however, they were wrapped in fiberglass and mastic materials. Unfortunately, one nick in the wrapping allowed contact with the soil. This exposure to the soil opened the possibility of corrosion
the entire length of the cylinder, which in some cases, could be as much as 70 feet.

While not specifically required by code, most elevator manufacturers have adopted the following installation procedure:

1. A steel outer casing is set in the hole which is typically 3'-0" diameter
     with a capped bottom.
2. Inside the steel casing a capped schedule 80 PVC pipe is set.
3. The hydraulic cylinder is set inside the PVC isolating it from the soil.

Figures 1 & 2 refer to the details of the pre-1985 and after drawings for Cylinder/Plunger Installations.