By: David S. Coleman, Brandon D. Selle, and Larry Massing

When the City of Stuart, Florida questioned their fire protection system they turned to GIS to analyze the situation. ArcInfo and ArcView GIS software were instrumental in identifying the spatial arrangement and hydraulic limitations of the protection system.

Outdated hardcopy maps and a more up-to-date digital tabular database were utilized with a digital basemap to create the fire hydrant coverages. The coverages allowed for a newer method to analyze fire protection.

In the analysis, a service radius of 500 feet for each hydrant was delineated through buffer generation to determine coverage. Flow data was collected for the 600 hydrants in the system, which allowed the assignment of the National Fire Prevention Association�s (NFPA) standard categories in the GIS. In the final map depicting the City�s fire protection, areas without coverage and low-pressure areas were easily identified and evaluated for correction by adding new hydrants.

This repair and improvement program has resulted in a color-coded mapping system based on hydrant flow rates, and painting of the actual hydrant bonnets to correspond with the map. The City�s Fire-Rescue Department now maintains laminated copies of the GIS-based map in each vehicle, and has readily available flow data on each hydrant in the system. In addition, the City now has an enhanced GIS that can be maintained and built upon in the future.

Geographic information systems (GIS) are widely known for their ability to simulate complicated real world phenomena, making them easier to understand. When the question "How good is your fire protection system?" was posed to the City of Stuart, Florida, they and their consultant Lindahl, Browning, Ferrari and Hellstrom, Inc. (LBFH) realized that GIS could help them answer this question.

From a fire protection perspective, GIS permitted Fire-Rescue Department personnel to evaluate key elements of the City�s 600-plus hydrant municipal water distribution network with respect to its adequacy for fire suppression purposes. In addition it allowed better decision making to lead to its compliance with the local adopted standards relating to fire protection. These standards were based on the National Fire Prevention Association (NFPA) and the Insurance Services Office (ISO) for fire flow requirements for specific property risks. The NFPA and the ISO rate each water system by its ability to meet minimum national standards for public safety. The results of the rating system impact the City�s liability and/or assets in meeting fire protection. Perhaps most importantly, an evaluation of the system could also result in improvements that reduce the risk of lives and property in the future.

The Fire-Rescue Department has for many years collected and archived in a database, fire flow data from each fire hydrant both public and private throughout the municipality and tracked the distribution of these devices on a hardcopy map of the municipality. Such data is operationally essential to the Fire-Rescue Department, so it may ensure an adequate volume of water is nearby and accessible for fire suppression purposes. This represents the basic premise by which the insurance industry operates when determining rates for specific properties. Thus, it is a significant element of the Insurance Services Office Fire Suppression Rating process.

The City of Stuart was motivated to evaluate and improve both its water distribution system and fire protection system in an attempt to positively affect the local insurance rates of its constituents. This could be accomplished by improving its Fire Suppression Rating and assuring that required fire flows were being delivered to specific properties. It was clearly apparent that such a task could not be accomplished in a timely fashion without the unique capabilities of GIS.

The scope of the task was twofold. First, it was necessary for the City to evaluate fire hydrant distribution, both public and private throughout the City. According to the Insurance Services Office, maximum credit is achieved when a fire hydrant is located within 1000 feet of a structure. Therefore the direction to the consultants was to evaluate existing hydrant distribution based upon a maximum protection radius of 500 feet per device and make recommendations to the City for additional devices based upon the outcome of the query.

The second direction was to evaluate the existing network utilizing GIS and hydraulic modeling in an effort to determine the capability of the network to deliver specific fire flows to specific areas throughout the City. These flows varied with respect to the areas evaluated. They ranged from 1000 gallons per minute at a residual pressure of 20 pounds per square inch for single family residential areas to as high as 3500 gallons per minute at a residual pressure of 20 pounds per square inch for larger unprotected multi-family and commercial occupancies. The consultants utilized for the most part existing data provided by the Fire and Public Works Departments in order to complete the analysis, this fact contributed greatly to the overall cost effectiveness of the project. Very little fieldwork was necessary to complete this project and when such fieldwork was necessary, either the Fire or Public Works Departments carried out the task.

In summary, the City had to provide the following to meet locally adopted requirements:

1. At least one fire hydrant with the ability to operate at a minimum flow of 1,000 gallons per minute (gpm) within 500 linear feet (as a hose lays) from a structure
2. In areas of higher demand, more than one hydrant within 500 feet of the structure with the ability to flow a minimum of 1,000 gpm simultaneously, and
3. In areas of the highest demand, fire flows up to 3,500 gpm.

Thus, to model the actual situation, GIS would show the spatial arrangement of the hydrants and the fire flow category of each hydrant.

In the past, the Stuart Fire-Rescue Department relied mostly on first hand knowledge of fire hydrant locations when a call came in. The best documentation of the hydrant locations was a map on the wall of City Hall that was under development. LBFH and the City took this opportunity to update and digitize hydrant locations, thus allowing them to undertake a modeling effort.

The effort spanned throughout various departments in the City. City Planning Department personnel worked with the Fire-Rescue Department and LBFH to map all the locations, precisely within a few feet on the City basemap. City Public Works Department personnel worked with LBFH to map locations and determine diameters of water mains in the City. LBFH compiled this information, along with a CAD representation of the City�s roads and shoreline, and created ArcInfo coverages. Two coverages, FHYDS and WMAINS, were "heads up" digitized and manipulated on top of a third coverage, BASEMAP. Draft maps of hydrant locations were output via ArcView for City personnel to quality assure and quality control by field inspection.

A hydrant identification system was needed to facilitate the mapping and modeling efforts. Thus, a hydrant identification system devised by the Fire-Rescue Department was used. The numbering system was based on geography, for example, hydrants 20xxx would all be found in the same area of the City. This hydrant identification number would also be the link to tabular data previously residing outside the GIS.

Tabular data was input and converted from various sources. Data existed for some of the hydrants, including hydrant type, date installed, manufacturer, and identification number. This data was preserved when possible. Although database development was not the primary goal of this study, it will facilitate efforts for inventory, operations, and maintenance in the future.

Directly pertinent to this study was the fire hydrant flow data collected by the Fire-Rescue Department, which routinely measures and records flows at each hydrant using standardized equipment. Hydrant fire flow was mathematically calculated to reflect the flow when the residual pressure in the distribution system is at 20 pounds per square inch (psi). This represented the lowest pressure the distribution system should have at any time. This data, along with identification numbers for the hydrants, was kept up to date by the Fire-Rescue Department in a spreadsheet file. After adjusting the hydrant identification numbers in the spreadsheet file to match the coverage, an ArcInfo JOINITEM was performed. Thus, with an up to date and accurate GIS database of the water distribution system and its hydrants in place, the analysis could begin.

The first step in the analysis was to create 4 separate coverages of fire hydrants based on the NFPA fire flow rating system. Table 1 shows the flow ranges, NFPA Code, and color. The color for each flow range would be the primary method for visualization of the flow adequacy on the GIS-based maps. Blue depicted the highest flows, and conversely, red showed the lowest.

The 4 new coverages were created through the ARCEDIT module, using RESELECT and PUT commands based on the FLOW attribute. The coverages were named as follows: FHYD-C, FHYD-B, FHYD-A, and FHYD-AA.

The next step was to depict the 500-foot zone around the hydrants, allowing easy visual analysis of the zones� spatial arrangement. These zones, or buffers, were created using the ArcInfo BUFFER command for each of the four hydrant coverages. Using the resultant coverages, maps with color-coded features (hydrant points and hydrant buffer polygons) were created as illustrated in Figure 1.

Figure 1.

To more accurately model the situation, the analysis needed to include major obstacles; certainly, firefighters cannot pull fire hoses over everything. Thus, an OBSTACLES coverage was created which contained geographic features such as large bodies of water, major roadways, and railroad tracks. The OBSTACLES coverage was displayed as bold arcs on the maps, making visual interpretation much easier.

ArcView software was then used to plot maps of the available data, areas requiring fire protection improvements could be more easily determined. The maps produced were given to LBFH engineers for this evaluation, who in turn marked-up maps with the improvements necessary to receive a higher NFPA rating. Then, additional coverages of proposed hydrants and water mains, P-FHYD and P-WMAIN, were created and additional maps were plotted. LBFH engineers could now evaluate the maps with and without improvements simultaneously. Figure 1 shows a sample of existing inadequate hydrants having low or no flow identified as red and orange zones. Further investigations of the low flowing hydrants were completed using historical flow data, basic hydraulics, and the best available information with regards to the layout of the distribution system in an attempt to provide corrective action. All of the recommendations for the installation of additional water mains were supported with further study and hydraulic models of the distribution system. These other modeling efforts supported the GIS-based findings. The results and evaluations were discussed with Public Works and Fire-Rescue Department staff during the development of the recommendations.

Some results of the study were readily apparent upon visual evaluation of the maps. For instance, there were gaps in the 500-foot buffer, which represented a potential lack of fire protection. Also, areas covered with red and orange stood out as low-flow areas. However, the maps showed that the overall scenario for Stuart was favorable. In fact, 70% of the hydrants produced flows in the highest range (blue) and covered a large part of the city. Of the remainder of the hydrants, 18% fell in the NFPA�s next highest range (green), 8% fell in the next range (orange), and only 4% fell in the lowest range (red).

Further evaluation led to specific recommendations for fire system improvement. The recommendations included the addition of approximately 30 hydrants, improvements to the water distribution system, and the identification of specific existing hydrants that required either further inspection and/or maintenance. In the case of the latter, the GIS-based maps made apparent these hydrants did coincide with engineering logic. One example was low flow hydrants found on large diameter water mains. Another example was several hydrants with extremely low flows relative to other nearby hydrants on the same water main. All of these recommendations were prioritized based on lowering risks to life and property. In most instances, the GIS was able to facilitate this decision making.

GIS technology facilitated this fire protection study in an extremely timely fashion, the graphical results painted a definitive picture of those areas of the City necessitating system improvement and made priority areas were clearly conspicuous. These attributes of GIS permitted the City to make better-informed decisions as to where capital improvement funds could be invested more effectively. This study provided the City with the information needed to achieve its ultimate goal, reducing local insurance rates.

The outcome of this project exceeded the Fire-Rescue Department�s expectations. The GIS format provided a clear and concise graphical representation of the existing hydrant distribution and their protection radii, as well as clearly defining those areas which were adequately protected in terms of fire flow and the areas which were marginally or ill-protected. By combining data spatially, which prior to this study had been isolated to individual City departments, the consultants were able to identify restrictions in the distribution network, which generally resulted in the discovery of closed or gated valves. This in and of itself was a major accomplishment of the project.

Since the recommendations were given to the City, the staff has undertaken a Capital Improvements Plan project to improve the fire protection system. High priority improvements are currently being completed and lower priority improvements should be completed in the years to come.

This repair and improvement program has resulted in the painting of the actual hydrant bonnets to correspond with the map. This caused enough interest that the local paper, The Stuart News, wrote a story about it (Figure 2).

Figure 2.

The City�s Fire-Rescue Department now maintains laminated copies of the GIS-based maps in each vehicle, and has readily available flow data on each hydrant in the system. This eases fire fighters jobs. Now, when they arrive at a scene, it is simple to tell what the hydrants� capabilities are.

Finally, the City now has an enhanced GIS that can be maintained and built upon in the future. Potential future plans include using the GIS for other operations, inventory, and maintenance programs for the hydrants, water mains and the mapping and incorporation of other geographic features.

Appreciation goes to City of Stuart Manager David Collier, Public Works Director Samuel Amerson, as well as other members of the City of Stuart staff who worked on this project. Also, appreciation goes to Steven Doyle and Thomas Vokoun of LBFH for their efforts and guidance throughout the project.

Insurance Services Office Public Fire Suppression Rating Schedule. 1980.

David S. Coleman, M.S.

GIS Analyst

Lindahl, Browning, Ferrari and Hellstrom, Inc.

2400 S.E. Monterey Road, Suite 300

Stuart, FL 34990

Phone: 561.286.3883

Fax: 561.286.3883

Email: lbfhst@gate.net

Brandon D. Selle, E.I.

Project Engineer

Lindahl, Browning, Ferrari and Hellstrom, Inc.

Larry Massing

Fire Chief

Stuart Fire-Rescue Department