Concrete and The Disguntled Employee

A recent article in the St. Louis Post Dispatch discussed a large damage to property at a concrete producer. Concrete is produced as a powder and hardens as water is added- we've all seen concrete trucks on the highway. In this instance, someone destroyed a huge supply of concrete and intentionally pouring water into a large tank that contained the concrete sunstance. You guess it- the material hardened and was unusable. To make matters worse, the company could not service cusotmers who ordered concrete, resulting in employee layoffs. The company suspected someone who had access to the company's facility and knew (obviously) what they were doing. How could this have been prevented?
Written procedures- properly implemented- may have prevented this from happening. Let's assume the person who created the damage was a disgruntled former employee. When the employee is fired, there should be procedures in place to ensure that this person cannot use their knowledge of the business to access cash or other company assets (vehicles, equipment, buildings, etc). Specifically: All keys, access codes, swipe cards, etc. should be returned and logged in as returned. Any codes, passwords used by employees should be changed. Finally, a manager or supervisor should be responsible for pulling a procedure manual off the shelf implmenting these procedures. Removing employees is a stressful process. However, don't make things worse by leaving yourself open to retaliation.