HomeMy WebLinkAbout1.02 Fire Sprinkler System - Water Supply Report 08.07.2015Shaner Life Safety
PO Box 1073, Frisco, CO 80443
970.409.9082; fax 970.797.1898
August 7, 2015
Michael G. Fa, NCARB
M.DesignFusion, LLC
6020 E. Monte Cristo Avenue
Scottsdale AZ, 85254-6534
Re: Glenwood Springs, FedEx Ground facility
In response to the requirement outlined in Ron Biggers' letter dated May 11, 2015, I have
conducted a review of the FedEx Ground facility to be located in Glenwood Springs.
The facility will be built in a rural part of Glenwood Springs which does not have access to a
municipal water system. The building will be sprinklered. To determine the necessary water
storage, calculations for both sprinkler system water and site fire flow must be conducted. The
following sections outline recommendations for fire protection systems as well as calculations
and code references for support.
Fire Sprinkler System/Water Supply
For the sprinkler system, NFPA 13, Installation of Sprinkler Systems, will be used as the design
standard. The system will be a standard, wet pipe system as the building will be conditioned.
This building is not intended for storage, but rather distribution and processing of FedEx
packages. That said, some short term storage may be expected during busy shipping seasons.
As noted later in this report, the maximum recommend height for any storage is 12'.
An Ordinary Hazard, Group 2 hazard classification is recommended. NFPA 13 defines this as,
"5.3.2.1 Ordinary hazard (Group 2) occupancies shall be defined as occupancies or
portions of other occupancies where the quantity and combustibility of contents are
moderate to high, where stockpiles of contents with moderate rates of heat release do not
exceed 12 ft and stockpiles of contents with high rates of heat release do not exceed 8 ft."
If storage is kept to a level of 12' or less, a single layer of sprinklers at the ceiling will provide
adequate protection. A standard wet pipe system, Ordinary Hazard, Group 2 at a height of
approximately 24' will carry a system demand of approximately 400 gpm inside the building.
Per NFPA 13, Table 11.2.3.1.2, 60-90 minutes of water are required. For this calculation, the
lower duration of 60 minutes is used in accordance with Section 11.2.3.1.3, "The lower duration
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Fire Protection Engineering Review Page 2
values in Table 11.2.3.1.2 shall be permitted where the sprinkler system waterflow alarm
device(s) and supervisory device(s) are electrically supervised and such supervision is monitored
at an approved, constantly attended location." A fire alarm system (to be detailed later in this
letter) will be provided to supervise the sprinkler system.
At 400 gpm for 60 minutes, the required storage for the fire sprinkler system is 24,000 gallons.
NFPA 13 generally requires a hose stream allowance to be added to the fire sprinkler demand.
However, in this case, because site fire flow is being calculated separately and because the water
supply is a private tank and pump, this hose stream is not included. The calculation for site fire
flow includes 1000 gpm of site fire flow which will qualify as meeting the hose stream demand.
The fire sprinkler system will be supported by a fire pump. This pump will be sized based on the
calculated hydraulic demand of the system.
Use of ESFR sprinkler heads — alternative to standard sprinklers
If package storage will occur above a height of 12', a more robust sprinkler system is
recommended. This can be accomplished with the use of ESFR sprinkler heads. Additionally, if
there is concern for the presence of the Material Handling System (MHS), the use of ESFR
sprinklers could provide an alternative to sprinklering within this system. The MHS will be
installed by FedEx's preferred vendor and will be typical of other FedEx facilities. Note that I
have visited the Kremmling, Colorado facility and have also reviewed photos of other typical
facilities. This system will be used to sort and move packages throughout the facility. Based on
my observations, the conveyer system does not required a separate level of sprinklers, nor will
storage over 12' be expected. However, this recommendation is provided in the event that an
alternative to standard sprinklers is necessary.
ESFR sprinklers flow considerably more water than standard sprinklers. A system demand of
750 gpm would be expected with the use of ESFR sprinkler heads. At a 60 minute duration, this
would require 45,000 gallons of water storage.
Site Fire Flow/Water Storage
For the site fire flow storage, NFPA 1142 is the recommended design standard. NFPA 1142,
Standard for Water Supplies for Suburban and Rural Fire Fighting provides a method for
calculating the minimum water supply required for a rural facility. Calculations are based on
building volume, use and construction type.
NFPA 1142's formula for determining minimum recommended water supply is as follows:
Minimum Water Supply = (Total Volume of Structure)/(Occupancy Hazard Classification
Number) x Construction Classification Number
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The Occupancy Classification numbers are assigned by Section 5.2, NFPA 1142 and are based
on the specific use of the building. The FedEx Ground building has been assigned an Occupancy
Classification of 4 which includes General Storage, Freight Terminals and Warehouses.
The Construction Classification number is assigned by Section 6.2 and is based on the materials
of building construction. Because this building is metal and of non-combustible construction, a
Construction Classification of Type I is assigned, which carries a .5 Classification Number.
Occupancy Hazard Classification Number = 4
Construction Classification Number = .5
Approximate Building Volume = 663,200 cubic feet
Minimum Water Supply = 663,200 cu.ft./4 x .5 = 82,900 gallons for site fire flow
This number will be rounded to 85,000 gallons for simplicity and to provide a small factor of
safety.
Per Table 4.6.1, NFPA 1142, this water must be made available to the fire department at a rate of
1000 gpm. The recommended distribution is through pressurized hydrants located per fire
department requirements. The minimum operating pressure of a fire hydrant is 20 psi.
Summary of Required Water Storage
Scenario #1 (Recommended)
Site Fire Flow = 85,000 gallons
Sprinkler Water (standard heads) = 24,000 gallons
Total: 109,000 gallons
Scenario #2 (ESFR heads, storage over 12')
Site Fire Flow = 85,000 gallons
Sprinkler Water (ESFR) = 45,000 gallons
Total: 130,000 gallons
The recommend water storage for this facility for fire protection and firefighting water is
109,000 gallons (130,000 gallons if ESFR sprinklers are used). Additional water needed for
domestic demand or irrigation must be added to this number. This represents a minimum
amount of water needed for fire protection use.
Fire Alarm System
At a minimum, a fire alarm system must be installed to monitor the fire sprinkler system and
provide occupant notification. Although only one is required at the panel, manual pull stations at
all exits are recommended to allow for quick activation of the fire alarm system in the event of a
fire. The system will require an outside horn/strobe above the fire department connection.
Horns and strobes will be installed throughout the facility to alert occupants of a fire. The
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sprinkler system waterflow and tamper switches will be monitored. The fire alarm panel will be
equipped with an automatic dialer to call the fire department if the system is activated. The fire
pump will also be monitored by this system. Temperature sensors and a tank level sensor are
also recommended features for the fire alarm system. This will allow for notification if the fire
protection system is in danger of freezing or if the tank level drops below the minimum required
level.
Of course, other building features such as exit signs, proper egress, fire extinguishers and
emergency lighting are required in accordance with the adopted codes of Glenwood Springs
building and fire departments.
I have attached a photo of a typical facility and a site plan showing the building location.
Please do not hesitate to contact me if you have any questions.
Sincerely,
Deborah L. Shaner, P.E.
Fire Protection Engineer
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