Peter, What you said is true if the drain system treats all fluids equally. But consider the difference between these fluids. It is much more important that sewage water, with its Constant Flow Rate, get to its intended destination and not leech its pollutants into the ground. Storm water, with a bursty Variable Flow Rate, will not cause environmental damage if leeched into the ground during overflow cases. What is needed is a drain system which can distinguish between storm water and sewage. Prabhu ______________________________ Reply Separator _________________________________ Subject: Re: a generic water encapsulation technique [Re: floods] Author: peter@tdi.net at SMTPLINK Date: 4/10/97 10:56 PM Kent W. England wrote:

We could also multiplex the rain water with the sewage water in a multi-mode drain system. Internet drain specialists tend to take religious points of view on whether we should have separate drain systems, should combine them, or outlaw one in favor of the other. But, clearly, encapsulation is the favored approach.

The multiplexed drain system will never work. Sewage water we know to be a fairly constant flow over time, and in fact sanitary engineers refer to it as having a Constant Flow Rate. Storm water, on the other hand, is very bursty in nature, and sanitary engineers describe that as Variable Flow Rate. In the old days they tried combining drain systems, sharing the resources between the CFR water and the VFR water, and called the result AFR (or available flow rate). AFR had one weakness, however: it relied upon a phenomena called precipitation shaping to keep the VFR storm water from interfering with the CFR sewage water. As the clouds and the ground didn't have enough buffering to do proper precipitation shaping, the result was a drain system which periodically suffered massive congestion, and all users were equally unhappy. -peter