What You Need to Know: Water System Operation

In the previous post we discussed the importance of accurate water supply analysis when looking at a new development.  In this post we will look at more details on public water systems, how they are designed and operated, and what impacts these have on the water supply available for a new development.

The public water system consists of all the components necessary to supply water to our homes and businesses.  This can include the raw water source, treatment system, storage tanks, pumps, piping and other components that deliver water to the customer.  While all these components are critical to delivering water; when looking at an existing water system’s ability to supply water for a future development, the most important aspect to understand is how the water provider maintains pressure on their system, as this typically has the biggest impact on the water supply for a new development.

At the most basic level, water departments typically maintain their system pressure or hydraulic grade in one of two ways.

The first and probably most common is with an elevated storage tank(s), commonly known as a water tower.  With this arrangement, the water system “floats” on the level of the water in the tank.  The tank elevation and the water level in the tank set the system pressure.  Pumps either at a water treatment plant, or a booster station are operated based on tank level.  When the level drops to a certain point, pumps are brought on line to refill the tank.   Larger systems with multiple pumps may bring on pumps in a staggered arrangement, with the first pump coming on at a certain water level and additional pumps brought on if the level in the tank continues to drop.  On some systems, the pumps deliver water directly to the tank; however it is more common that the pumps discharge into the distribution system which, when pumping capacity exceeds system demand, will fill the tank indirectly.  Appropriately, this method is called an indirect pumping arrangement. Continue reading “What You Need to Know: Water System Operation” »

What You Need to Know: Meeting Specialty Fire Hydrant Flow Requirements

Every jurisdiction has fire protection codes and requirements for new construction and remodels.  Many require only that you follow the International Fire Code and have signed sealed hydraulic calculations, but others have their own requirements. 

Alternatives in Engineering can help you with signed sealed hydraulic calculations and any unique requirements a jurisdiction can throw at us.

Here are some examples of unique requirements around the country:

City of Austin Fire Protection Rule requires the following:

For hydrant flow calculations, follow Appendix B of 2012 IFC but limit reduction of fire flow to 50% for certain building types

Accepted “C” values for calculations are 110 for PVC & Copper 80 otherwise

Austin Water also requires General Construction Notes and project information on drawings.

Port St. Lucie, FL requires the following in stamped sealed calculations: Continue reading “What You Need to Know: Meeting Specialty Fire Hydrant Flow Requirements” »

What You Need to Know: Water Supplies for New Development

While seemingly a small part of the overall scope of a large development, accurate water testing and modeling of infrastructure to support new development is critical to ensuring adequate water supplies are available without excessive costs.

A complete water supply analysis for a new development consists of three critical parts, testing and analysis of the pubic supplies, accurate estimations of the water needs of the development, and proper modeling of the water infrastructure associated with the development.

Determining the capacity of the existing water system

The first step is to determine the capacity of the public supplies.  This generally begins with obtaining flow test data.  Performing a hydrant flow test is a relatively simple procedure, and many jurisdictions will provide this information for free or for a minimal charge, but often this low-cost option comes with a hidden expense.  Many of the public personnel that perform flow testing on their system fail to understand the importance of the flow test data, tests are performed on the incorrect hydrants, an inadequate amount of water is flowed compounding errors, and the accuracy of these tests is often of concern as low cost, or poorly calibrated gauges are commonly utilized.  Continue reading “What You Need to Know: Water Supplies for New Development” »

Water Supplies for Fire Protection Service, Part 1

By Chad Lueders, P.E.

The vast majority of fire protection systems utilized in buildings today rely partially or completely on the municipal water system to provide the water necessary to control or suppress the fire.  While seemingly only a small part of the overall fire protection system, an understanding of how municipal water systems are operated, and what their limitations are, is vital to ensuring a reliable and functional fire protection system.

At the most basic level, water departments typically maintain their system pressure or hydraulic grade in one of two ways.

The first, and probably most common, is with an elevated storage tank(s), commonly referred to as a water tower.  With this arrangement the water system “floats” on the level Continue reading “Water Supplies for Fire Protection Service, Part 1” »

Why You Should Choose a Third Party to Perform a Fire Hydrant Flow Test

By Scott Repke, P.E.

When designing a fire sprinkler system for any building, one of the first, and most important, steps is to analyze the water system in the area by having a fire hydrant flow test performed. Why is this so important? To work properly and control a fire, a sprinkler system must flow a certain amount of water with enough pressure to be effective. The entire design must be based upon how much water flow and pressure is available from the water system – if this information is not accurate, the design may fail and the fire will not be controlled!

There are many choices when it comes to getting a flow test done. Some will go right to the source and have the water department or fire department perform a test. Others have the fire sprinkler contractor working on the project go out and run a test, while yet another Continue reading “Why You Should Choose a Third Party to Perform a Fire Hydrant Flow Test” »