Improved Water Flow Betters Insurance Rating
As of March 1,1983, the City of Decatur, Ga., was given the ISO insurance classification of “2.” The class 2 insurance ratings are not rare in themselves, but when your entire city only encompasses a total area of 4 square miles, it is extremely unusual to have a classification this low.
Decatur, just east of Atlanta, is the DeKalb County seat. Population at night is roughly 18,000 but swells to nearly 100,000 during the business day, due to the county offices and other businesses. Therefore, the small city has the typical characteristics of a metropolis during daylight hours but tapers off to a small town at night.
Decatur is an old city and, in fact, is older than its larger sister city to the west, Atlanta. Some of the water system has been in the ground many, many years, and low flows are obtained in various areas. At one time, Decatur had its own water system but it was sold to DeKalb County. DeKalb has significantly upgraded the entire sytem.
Previously, Decatur had a class 5 ISO rating, but due to the county’s adding some 20-inch and 12-inch mains to assist in regridding the existing large mains, water problems were then limited to small areas, mostly in residential neighborhoods.
With better water supply, the Decatur Fire Department decided to try some large-diameter hose. The initial bids were for either 4 1/2 or 5-inch hose and a portable hydrant. The low bid was for 5-inch so the city purchased 600 feet. This was loaded onto one of the fire department’s three engines, while the remaining half of the hose bed was left loaded with 3-inch hose. From the various drills and tests that were conducted on several fires, the data compiled showed the 5-inch was preferred and additional hose was ordered. The eventual goal is to have 600 feet of 5-inch hose on each of the three engines, or a total available stock of 1800 feet.
The engines were also adapted for other hose changes as the booster lines were removed. The smallest line now carried is a preconnected l 1/2-inch. There are also preconnected 2 1/2-inch and a deluge gun on each engine. At this time Chief Sherrard White can rapidly “move” his hydrant 600 feet by use of the 5-inch hose and a portable hydrant.
Recently, the city had a major fire. With the total on-duty response of three engines, one aerial, one chief officer and 15 men, the department was able to flow 3500 gpm, supplying two 3-inch feed lines to its elevating platform, four 1 1/2-inch and two 2 1/2-inch handlines from one 5-inch lay. Divided out, this is roughly 232 gpm per fire fighter on the scene.
These flow results say a lot about the value of the large-diameter hose. The out-of-service time while hose is reloaded and equipment is returned to a state of readiness for the next alarm is greatly reduced, since there are no longer piles of “spaghetti” in the street. The 5-inch hose can be reloaded wet with very little effect on its useful life.
Several cities have decided that 4-inch hose instead of 5-inch is the ideal size and feel the benefits are sufficient as a reduced cost.
Carson City, Nev.’s goal was to equip engine companies with sufficient hose of the proper diameter to supply 1000 gpm to a fire scene 1000 feet from a water source. It chose 4-inch hose after considering several factors:
- The capability of the city’s overall water system,
- Which areas of the city would require large quantities of water in order to mount a successful attack, and
- The distance between hydrants in those areas.
The Decatur objectives were to:
- Provide optimum gpm per engine and fire fighter, with available resources.
- Provide a fire flow of 3500 gpm with on-duty personnel, normally about 14.
- Decrease equipment and apparatus out-of-service time following a major fire so that the department could be prepared to respond to another incident as quickly as possible.
Assistant Chief Mike Lane stated that purchasing 5-inch hose to move water from a poorly supplied hydrant is a waste of money because the flow will not be sufficient to use the large-diameter hose effectively. The DeKalb County water system upgrading of the Decatur main system has now provided adequate water close enough to make the use of 5-inch hose very practical.
The ability to move good water supplies into streets and areas where less than desirable hydrant flows were available became a bonus when the Insurance Services Office rated the department recently. This, along with their rigid training program, inspections, pre-fire planning and public education helped gain the class 2 rating. Chief White and Assistant Chief Lane both feel that a city of only 4 square miles having a class 2 insurance rating may qualify them as the smallest city in the United States to have an ISO rating this low.