This was posted on Peter de Jager's forum. It describes the date/time calculations necessary for disposing sewage.
I used to live in Mahattan Beach, California. The next town north is El Segundo. There resides an outflow system for Los Angeles' sewage. Once in a while, we could smell it, or thought we could.
After reading this, I'm glad I moved.
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Date: Wed, 10 Jun 1998
From: "Huggins, Paul P"
Subject: Re: Embedded Systems: Water, Sewer, Traffic
An outflow system allows sewage or waste to flow into river/sea one hour either side of high tide. The system uses a controller linked to a PC that has a tide table of the form dd/mm/yy. The computer looks at its system date then checks this against the tide table to see when it should stop the flow.
The language the system is written in has a bug which means that the year 2000 is represented as 100. Come one hour after high-tide on 1/1/2000 there system checks for a match against 1/1/100. It can't find such a match and therefore remains open...........
Year 2000 Project Co-ordinator
BHP Petroleum ERAME