The Town vs. The Fire Department: The Determination Of Fire Risk Levels

At some point after identifying the level of fire risk in your community, you will have to address the most serious question of all: Just how much fire protection is needed to address the risk? Before going any further, an important distinction must...

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To more closely approximate the real world, the National Fire Aca-demy has determined that the initial attack capability is to be measured after 10 minutes. This allows five minutes for turnout and response, then an additional five minutes of operational deployment time. We would suggest that rather than conducting responses to actual buildings with apparatus and personnel, approximations be made. You need to determine:

  • Average time needed to process an alarm.
  • Response time to your identified target hazards.
  • Time variations for the different fire stations.
  • Time variations for the companies due to respond.

Response time information to certain districts may be available and could be used for this purpose.

When we perform a municipal risk survey, we always suggest the same approach. Trials are conducted using a drill ground, training facility or someplace where a safe trial can be held. Using a stopwatch, apparatus can begin to work at appropriate intervals based upon the pre-determined times.

Apparatus would begin to operate at staggered times based upon their designated arrival times. At the 10-minute mark, the amount of water flowing, in concert with the number of personnel delivering the fire flow, is recorded based on these criteria:

  • The number of 200-foot hoselines each manned by two personnel in protective clothing.
  • One pump operator for each pumping engine.
  • Minimum of two personnel for search and rescue. (An additional two people for each 2,000 square feet of occupied property must be factored in for larger buildings.)
  • One person for support functions, such as forcible entry and utility controls.
  • A minimum of two people for ventilation. (In situations requiring roof top ventilation, these two people must reach the roof location within 10 minutes.)
  • One person must be available for command.
  • One person to be safety officer.

1 1/2 - inch line 100 gpm
1 3/4 - inch line 150 gpm
Two - inch line 200 gpm
2 1/2 - inch line 250 gpm
(Must have three properly attired personnel.)

The evaluator will record all appropriate observations. This is done to determine the operational capability of the department. It is also used to ascertain the level of fire suppression resources which can be delivered at the 10-minute mark.

With the sustained attack flow, a paper analysis of the department and its water supply is usually sufficient. Owing to the logistical problems of developing a large sustained attack flow, this is an earlier approach. This is also done because most jurisdictions will not want to disturb mutual aid fire units for the water delivery capabilities that are needed in excess of their own. However, periodic large mutual aid drills can be conducted to confirm hypothetical figures and meet various requirements.

Suppose we have determined that a target hazard exists with an initial attack flow requirement, within its largest open area, of 750 gpm. During the drill ground simulation, you find that at the 10-minute mark, the following situation exists:

  • A 1 3/4-inch hoseline is operated by two personnel wearing full protective equipment (including self-contained breathing apparatus). A pump operator is at the pumping engine.
  • A crew of two people is searching the 4,000-square-foot building.
  • One person is in the building with a search crew for forcible entry.
  • Two people are on the roof performing ventilation.
  • A fireground commander is in place to control the operation.

Is this a force sufficient to protect the property? NO, because where a flow of 750 gpm is indicated by the flow formula, only 150 gpm is available. Where two people are searching, four would be required. There-fore, we have a deficiency of 600 gpm and insufficient firefighters to deliver water and search the building. At this point, there is an unprotected risk level of about 600 gpm in the initial attack formula for the target hazard.

How is this shortfall to be addressed? The answer lies at the heart of the our next column. We are going to begin studying how you go about developing a community fire defense program.

Over the past few columns, our discussions have centered on the need for tailoring fire protection delivery systems to the actual needs of the community. The subject of fire risk has been presented as it relates to the delivery and consumption of a community's fire protection resources.