The Fire Suppression Rating Schedule (FSRS) recognizes alternative water supply systems, including dry hydrants, suction points, large-diameter hose relays, and hauled water using tanker shuttles.
The water delivery system must be available 365 days a year and provide 250 gpm for a 2-hour duration within 5 minutes of the arrival of the first apparatus. If a community uses a dry hydrant or suction supply point, ISO may need certification of the water capacity available during a 50-year drought cycle — by a state-certified professional — and many state and local governments have geological engineers or hydrologists who can provide that information. A good place to start is with the local department of environmental conservation. ISO treats suction points — with or without dry hydrants — in the same way it treats standard fire hydrants. Any property within 1,000 feet of a creditable suction point may be eligible for a protection class better than Class 9, provided the building is within 5 road miles of a responding fire station and the community has obtained 20 percent credit or more under the FSRS.
ISO may extend credit beyond 1,000 feet of a fire hydrant when the company uses large-diameter hose — if the fire department can demonstrate a standard procedure for deployment of hose and establish a relay operation.
To determine your fire department’s eligibility for recognition of a tanker shuttle, ISO needs to understand the delivery capability of each apparatus. ISO considers:
- fire-site pump capacity
- drop-tank capacities
- distance of responding apparatus from the fire station to the fire site
- distance of responding supply pumper to supply site
- distance from the fire site to the supply site
- amount of water carried by apparatus
- discharge rate of water supply apparatus
- fill rate of water supply apparatus
- quantity of water available and the rate available from the supply source
- set-up times
The procedure for determining your system’s capability involves running a timeline analysis. ISO considers apparatus arrival times, travel times, discharge rates, fill rates, fire flow at the fire site, wait time for apparatus to fill or discharge their water supply, and supply delivery capability.