The Carlisle Mosquito Online

Friday, July 18, 2008

Carlisle Fire Department’s cistern project improves fire protection

How can a community improve its firefighting ability when it has no municipal water supply? The short answer is that the fire department has to be aware of every possible water supply that can be used to battle a fire and it must be able to get the water to the site quickly.

Excavation for the 30,000-gallon Oak Knoll fire cistern was underway during the winter of 2007. (Courtesy Photo)

According to Fire Chief David Flannery, after a 1927 fire in the town center, Carlisle considered building a water tower on Schoolhouse Hill (site of current school) with the hope that gravity could be used to deliver water to the center in the case of another fire. Although the tower was never built, fire ponds were dug throughout the town to augment natural water sources. Today the Carlisle Fire Department is implementing a plan that will eventually provide a creditable water source within 2,000 feet of each residence in town. The plan, known as the cistern project, involves identifying the areas in town that do not have an adequate water supply, prioritizing those areas and providing a cistern, or underground water storage tank, for each of those areas.

New firefighting standards

Current standards set by the National Fire Protection Association (NFPA) for rural fire protection require larger and more consistent (drought resistant) water supplies. According to Flannery, “A source must provide 500 gallons per minute for one hour to meet the NFPA standard.” Flannery noted that by utilizing all of the fire trucks, the department can arrive with approximately 6,000 gallons of water which could last for about 10 minutes of firefighting. “If there is no supply nearby, we can call in tankers from Billerica, Lincoln, Boxborough and Hanscom, and begin shuttling the tankers from water sources to the site. But that takes time. To be more effective we need a source nearby.”

Flannery noted that cisterns are the current standard recommended by NFPA but that Carlisle

Hose is connected to the completed Oak Knoll cistern during a Fire Department drill this past May. (Courtesy Photo)

began requiring cisterns for all subdivisions more than 20 years ago. “In towns that have a municipal water supply developers are required to provide hydrants and connections to the water supply,” Flannery explained, “Here we require cisterns at a fraction of the cost. The first cistern was used in the Munroe Hill/Aaron Way neighborhood. A 5,000-gallon cistern was used, since there was no volume standard at the time. Later a 10,000-gallon cistern was required at Elizabeth Ridge. But today we require at least 30,000 for any new development.”

Each cistern has a well and pump to keep it filled, therefore making it less vulnerable to drought than the fire ponds. Flannery noted that cisterns in new subdivisions are sometimes close enough to be used in other nearby neighborhoods. Currently, there are 32 cisterns in Carlisle.

Effects on fire insurance

To determine the level of fire protection available to a homeowner or a community, insurance companies use ratings supplied by agencies such as the Insurance Service Office (ISO). These ratings are based, in part, on the size and location of an adequate water supply. The rating received by the town or neighborhood has a direct effect on the cost of homeowner’s insurance. Flannery noted, “Towns are rated on a scale of 1 to 10 with 10 indicating ‘no protection.’ A city like Cambridge would be a Class 1. Carlisle is currently rated a Class 9, meaning ‘unprotected.’ Most communities without municipal water supplies are Class 9 but an increase in the number of cisterns would help move the town to a Class 8B, or ‘limited water supply.’” According to Flannery, to receive this rating, Carlisle would need to show “creditable” water sources. The 30,000-gallon cisterns are acceptable, but for natural sources such as ponds to be deemed creditable, pipes must be installed by a registered engineer and a hydrologist must ensure that the source can provide at least 30,000 gallons of water even in a 50-year drought. “The Benfield Pond has worked well for us, but it is not always easy to get approval for natural water sources.” Flannery indicated that the town would likely ask to be re-rated soon, “Carlisle has done a significant amount since our last rating about 15 years ago.”

Carlisle cisterns

At a recent meeting of the Board of Selectmen, Flannery outlined progress on the cistern project, “In the last two decades the town has often been able to incorporate cisterns at no cost to the town as part of the construction plans of new housing developments. However, some regions of town – particularly the town center and neighborhoods that are away from the newer subdivisions – need additional sources of water.” Flannery noted that after risk analysis had been completed, 12 areas had been identified as having inadequate water supplies for firefighting and those areas had been prioritized.

Criteria used to identify higher risk geographical areas include: the number of houses, the density of the housing, the age and size of the structures, adequacy of and distance from natural water sources, elevation and distance from the fire station. The potential for development in the area was also considered, since developers must now provide cisterns. As a result of the risk analysis, the following areas were identified as highest priority: Oak Knoll Road/Hemlock Hill, Carlisle Center and the Autumn Lane/Estabrook Road/ Bellows Hill Road area.

Town-financed cistern

In May 2006, Town Meeting authorized spending $200,000 for the installation of cisterns and in February of 2007 construction for the Oak Knoll fire cistern began. According to Flannery, “It was hoped that a cistern could be installed for approximately $100,000. The original contract for the 30,000-gallon Oak Knoll cistern was $91,000, however, unexpected ledge was uncovered during excavation and the associated blasting and ledge removal increased the cost by $34,657.” Flannery added that the cistern was quickly put into use. Less than a year later, Carlisle firefighters used it to combat an out-of-control brush fire on Oak Knoll.

Future plans

Flannery stated that the next town-funded cistern would be situated in the town center, most likely at the fire station. He reiterated the department’s plan that eventually all dwellings should be within 2,000 feet of a water source. “This is an issue of fire safety. If we do a number of things we can also change our rating and decrease insurance costs for everyone in town. But if you are already near a cistern, it can already be lower. Call your insurance company.” ∆

Priority Ratings

for Additional Cisterns

1. Oak Knoll Road; Carlisle Center; Autumn Lane/Estabrook & Bellows Hill Roads.

2. Lowell/Ember Lane/Orchard Acres Drive; School Street near school.

3. Evergreen Lane/Forest Park & Carlisle Pines Drives; Bedford Road/Stoney Gate; North Road.

4. Judy Farm & Heald Roads; Concord Street 100 - 500; East Street/Ice Pond Road; South Street.


© 2008 The Carlisle Mosquito