Looped distribution system

[capnspa]

We are reviewing plans for a new theme park water distribution system. At this time it is to be tapped off of an 8 inch municipal main at one point and is a looped 8 inch on the property, there are about 10 hydrants on this system and it will also be the domestic water supply for the park.
The fire flow calcs are acceptable with one tap.
What is considered good standard practice for the number of taps off of the main line into an area. Their doesn't seem to be a standard in any codes that I have researched that give the number of taps off of a main line. I have seen different municipalities that have many different rules on this.
Although the system is looped within the property it is not looped off of the municipal main line.
Thanks, TWM

 

[rconner]

I noticed you had not yet gotten any response to this inquiry. I am not an expert in such designs, nor in whatever fire protection/risk management/insurance codes or local practices govern or otherwise deal with such things as theme (or amusement?) parks. You may wish to contact someone closely involved with this business, as it is possible such decisions could effect safety as well as insurance rates (perhaps depending on many potentially complicated factors, including what you have stated but maybe also what is actually in and around the park). However, I suspect it would probably be a good idea, if there is any way possible, to at least figure out some way to provide a "looped" supply to this system. Apparently only one "tap" (hydrant?) out of a group of ten to be available at one time, I would assume spaced throughout the park (with other theme/water demands?), and also drawing from a single-feed line sounds like a combined assumption that could eventually be questioned by someone. I think by doing a brief web search you may probably find that there have been some fires in some parks somewhere that resulted in folks hooking to more than one hydrant for water supply and even "made the news" (e.g., while I'm sure a far larger park than yours, you might be interested in the account at

http://www.nfpa.org/categoryList.as... Journal®/May / June 2002/Online Exclusives).

There are maybe even some folks making a living sort of from this business, such as

http://www.themeparksafety.com/.

 

[Maury]

The single connection to the municipal system means that the service line within the site isn't truly looped. I'm surprised that your fire flow calculations show that this is adequate, but maybe the theme park isn't tht large. Make sure your calculations are based on available pressures during the peak depend time. Have you or the municipality done a fire flow test near the point of connection to verify this? It would be preferable to have two or more connections to the public main, separated as much as possible, depending on the size of the service main. This does create a problem if the ystem has to be metered, you would need more than one meter.

 

[gtrainor]

A two point connection should almost always be required. Not so much for adequacy of pressure and flow, but more for safety. If one connection point is broken or shut off for repairs, then at least the flow can come from the other connection point. Even if the points of connection were relatively close at least you would have two supply line pipes.

 

[WayneMacD]

One service connection and an internal looped system is not unusual, especially for manufacturing facilities and large properties that will be metered based on total flow used on the property from one large meter. The loop will spread out your servicing ability internally within the property to reach all required serviced areas.

It sounds like you have determined that the fire flows will be adequate based on this arrangement. You may want to determine what your expected consumption will be, as if it is low, you may run into low disinfection residuals and stagnant water on the site.

Many municipalities do not want to incorporate private looped systems as free flowing entities with two or more services unless they take ownership and manage the infrastructure (e.g. a subdivision). From a consumption standpoint, numerous services are more difficult to control, and from a health perspective, a back-flow preventer should be installed to prevent any backflow into the municpal system.

If, however, fire flows are not adequate, additional services may provide the required flows, with back-flow preventers on each service and a Pressure Reducing Valve which will open one service during large flows only.