By Kyle Dent
Part 1 (March 2022) began the discussion on developing an alternative water supply (AWS) for departments whose service areas are expanding beyond their municipal water supply sources.
It reviewed how to understand needed fire flow (NFF), identify and classify natural water sources, and the logistics of suppling water for meaningful fire attacks. Part 2 will discuss methods of moving water.
The two primary methods of water delivery are relay pumping and tanker shuttles. Both are very effective delivery platforms, and both have their place in your AWS. Typically, relays can safely move a greater quantity of water with fewer resources than a tanker shuttle. However, they can have a long initial setup time to start a sustained flow and can be restricted by distance. Tanker shuttles are better at long distance movements but require lots of moving parts and personnel.
Relay Pumping
Relay pumping is using two or more pumpers, working in series, to boost inadequate water pressure over an extensive distance from source to incident (photo 1). Two common types of relay pumping are a maximum distance relay (MDR) and a constant pressure relay. The MDR is a preplanned event, generally applied at target hazards. This method is covered in most textbooks and uses a chart that reflects the maximum distances a given quantity of water can move through a select hose size. This chart takes into account pump size and higher pump pressures used to achieve these flows. The chart will tell you the maximum spacing you can use between apparatus to achieve a given flow. This will allow you to plan the layout to a given event at said target hazard.
The constant pressure relay is simply using what you have on that first alarm to start and then plugging in additional apparatus as they arrive or as needed. Pressures generally start at 100 pounds per square inch (psi) pushed forward and can escalate to 125 psi and 150 psi from the source. Once a flow is achieved, it is held constant, and any excess is managed using dump valves on the apparatus to bleed off unused pressure.
Note: When using dump valves, it’s best to direct flow in a safe direction. You can use a section of 3-inch hose from the discharge and direct the flow wherever you want. In colder climates, you don’t want to create a skating rink next to your engine (photo 2).
If more is required, a pressure increase to the next setting is started from the source and pushed forward by each successive pumper in the relay to the attack; then this pressure is held. The maximum flow that can be attained will be set by the resources available. This may start with only a source engine and an attack engine. Keep in mind more than 500 gallons can be moved over a mile through 5-inch hose with no relay. Usually at least one relay pumper can be present mid-relay and decent volume can be produced, though the exact gallonage will vary depending on what the distance is between pumpers.
Now let’s look at what our effective reach will be so we can determine at which fires we can use relay pumping and which fires will need a shuttle. We will suppose for these delineations that we are trying to set up with a first alarm. Extended scenes with multiple alarms and strike team packages allow for different tactics, and larger distances can be covered, but we are trying to set up with immediate availability and begin sustained water flow with first-alarm units. So, we can first look at how much total large-diameter hose (LDH) arrives with the first alarm.
In my department, the response package for a confirmed structure fire in these areas will be three engines, one truck, and one tanker. The engines and tanker each carry 1,100 feet and the trucks 500 feet. When we drop, we will keep 100 feet in each hosebed for burst hose, so 4,400 feet of hose will be on the first alarm. This would seemingly be the effective range of our relay capability. Using a MDR or any type of preplanned event, you have a better chance of actually getting all of that hose. The reason is the first-arriving unit will know exactly where to stop and lay in, dropping its 1,000 feet and arriving perfectly at the structure. The first engine needs to get on scene and set up to begin fire flow, so a reverse lay and then doubling back to the fire will take too much time. MDR allows for every apparatus to know their lay points, who needs to set up in the relay, and where. This can be done more rapidly and efficiently. In the constant pressure relay, the attack engine will likely go to the scene and then each arriving unit will lay to the source until it is reached or from the source to the fire, depending on the logistics and locations of the scene and the source.
We have a 12,000-square-foot church in our relay response area. This church is 3,240 feet from the waterway at the top of the road. The constant pressure relay would lay out as follows:
- The first-due engine responds to the fire and sets up to begin flow at 250 gpm.
- The second-due engine arrives and lays 1,000 feet from the attack engine toward the water source and then continues to the source to set up a draft and pump as the source engine.
- The next apparatus to arrive in this area will be the tanker, which will lay an additional 1,000 feet and then proceed to the scene and prepare to supply the attack engine using a rural hitch method. (The attack engine lays a section of hose out from its intake; at the end is a siamese. The tanker attaches to one inlet of the siamese and begins nursing the attack engine. The relay hose is attached to the other side of the siamese. Once the relay flow begins, the flow can transition from the tanker to the relay flow without interruption.)
- The truck will arrive next and drop its 400 feet and return to the scene to set up for truck work.
- The last engine will arrive and lay the remainder of 900 feet to the source and takes its place as a relay pumper at the 1,600-foot mark. Once set, the water can begin to move forward and fireground flow can be drastically increased. So, if we expect water flow to begin at the 5-minute mark and that flow to be 250 gpm, then with a nurse tender set up (our tanker is 3,000 gallons) we have around 21 minutes from arrival on scene to having the relay established. That is more than enough time to be up and running. Also consider that with time and proficiency, 21 minutes is enough time to bring in additional mutual-aid engines and can eventually allow you to stretch your radius of capability wider than just your first-due apparatus. But again, this takes training and experience to gain that proficiency as a department.
For larger events, the use of “pipeline” engine companies can bring in large volumes of water to a fire scene to supplement an existing municipal supply or supplement a smaller initial relay setup. A strike team of “pipeline” engines can bring 4,500 to 5,000 feet of 5-inch hose with pumpers spaced 900 to 1,000 feet evenly, giving the ability to move serious quantities of water and pressure to a large event.
When using any form of relay operation, remember the basic rules of relay pumping. The performance of the relay will not exceed the size of the smallest pump or the smallest hose in the relay. We found out that because we never considered any real form of distance relay pumping, our apparatus were ill-equipped to do it efficiently. Some of our pumpers were 1,250-gpm pumps, and all the discharges were 2½-inch. When mixed in with our 1,500-gpm pumpers with 3-inch discharges, we were always limited by what volume we could get out of the 2½-inch discharge or by the diminished pump capacity of those pumps as they struggle to keep up with advancing a given volume.
1 Relay pumping. (Photos by Justin Cammarata unless otherwise noted.)
2 Watch out where you operate your dump valve.
Another issue we found was that some of our intake valves were 5-inch storz to 3¼-inch. Now we purchase intake valves with at least 5-inch openings at the back, but it was obvious which pumper was letting less water into its pump. Often, we can buy the right pump with the right engine size and then kill ourselves with the plumbing and appliances we use with it.
So, when we look at our effective reach for a relay, from the credible water source in a given area, we will set it between 4,400 feet with target hazards and 3,400 feet from any other structures. Once we breach that distance, we are now anticipating switching tactics to a tanker shuttle.
Your ability to become proficient at relay pumping can pay real dividends in hydrated areas as well. Many times we may have target hazards that, if under any sizable fire involvement, can quickly overwhelm the capacity of the immediate hydrants that service this structure. The ability to tag outside hydrants on separate looped mains and bring this forward to the fire scene can open a whole new world to your firefighting capabilities.
3 Using tankers to move water from the source to the scene.
4 A diamond pond arrangement. (Photo by author.)
Tanker Shuttle
Having set the parameters for our relay pumping capabilities, it’s time to look at how to move water outside of this reach. This will be through tanker shuttles. Moving water from the source to the fire through tankers is an essential skill in rural firefighting. Setting up a tanker shuttle focuses on four components—the number of tankers, the dump site, the fill site, and routes—to get your AWS up and running. Deficiencies in any one of these can cost you in the production of gpm (photo 3).
How many tankers. Deciding how many tankers will be most dependent on the NFF and the distance to your water source. Once you know those two things, there are a few methods for calculating the number of tankers needed. From our earlier discussions, we know that we are minimally responsible for at least 250 gpm sustained, but for our fire needs, 500 gpm is the best minimum starting point. Now that we know our area and have tagged where the primary water sources are, we simply locate the nearest one to the fire event to which we are responding. There are a few models for making these calculations. They work well, but T = 0.65 x 1.7D and CFC = V/A+B+T seem a bit much to run through your head while you’re responding to your event or even when first on scene and trying to manage initial command. These formulas are great for preplanning an event, typically target hazards. Once again, what would be best for the fire we weren’t expecting? How about this: tank size/sum of travel time + fill and dump times – 10%.
Let’s look at the parameters of this formula. Tank size is exactly that, how much water the tanker carries. This is where it is important to know the particulars of not only your department’s tanker but also of the tankers in your surrounding area. Typically, tanker shuttles are a mutual-aid event.
5 An inline pond arrangement.
6 A fill site using draft.
So, let’s start with a 3,000-gallon tanker. Travel time: ISO uses 0.65 x 1.7D; this reflects a tanker traveling at 35 mph and its corresponding acceleration and deceleration factors. It’s not user friendly. So, we make the travel time average 30 mph, or a ½ mile a minute. Now we simply take the total distance (round trip) and multiply it by 2. So, three miles (round trip) is a travel time of 6 minutes. (When running the time using ISO, don’t forget to double it—the ISO formula automatically outputs a one-way time. The time differs by seconds.)
Next come fill and dump times. These are estimated at an “industry standard” of fill rate at 1,000 gpm and dump rate at 1,000 gpm. For our 3,000-gallon tanker, that totals 6 minutes. So, we are left with 3,000 gal/12 min = 250 gpm – 10% (another “industry standard” value on waste and loss in tanker use) = 225 gpm. So, a 3,000-gallon tanker with a water source 3 miles away (round trip) can sustain 225 gpm for your fire event. If your NFF is 500, then at least three of these tankers are needed.
There is one more consideration that you should not overlook. A tanker shuttle is a constantly moving event. The tankers can be moving, nonstop, for quite a while. Mechanical equipment fails. We have all had it happen. We always add a plus one on the end of our equation to account for Mr. Murphy. With that many moving parts, the chances go up that at least one has a mechanical issue. So now we are at a four-tanker shuttle.
Dump site. How close you get to the actual fire scene is not always up to you. So, take the following principles and shove them as close to the scene as you can. First, there is pond layout. Once the ponds are set and filled, they are set and that’s where you are going to operate, like it or not. Make a plan early. How much space do you have for ponds? Generally, you want around 10 times the NFF as storage on the ground. So, if the NFF is 1,000 gpm, then you’ll want 10,000 gallons of storage ponds on the ground. I typically do not include the main drafting pond as part of that storage, but that’s debatable. For the 500-gpm flow, you’d need at least two to three ponds on the ground. Also, keep in mind that some of your responding tankers may be less (or more) than 3,000 gallons. Typically, those tankers will carry ponds with a capacity that corresponds to the gallonage they carry.
Next, there are space considerations: Are you going to run your ponds in a diamond pattern or inline pattern? Diamond is going to be your best bet if you have exclusively rear dumping tankers. This design allows the tanker to have an avenue to reverse to the pond without turning at a complete 90° and thereby cutting off the road all together. However, this design takes up large amounts of space—taking a 13 x 13 pond and turning it diagonal now takes up 18.5 feet of space. Residential streets average about 16 feet, so this won’t work. For large commercial events or wherever you have lots of room, diamond is great (photo 4). Otherwise, an inline setup is more feasible.
Inline ponds are favorable for side dumping tankers and give the ability to keep one lane of travel open for the tankers to approach, dump, and depart. Typically, this may mean that your drafting engine will have to be inline with the first pond as well. In essence, set up the dump site so there is no, or very little, tanker repositioning to dump (photo 5).
Fill site. Most important for selecting a fill site are accessibility to the water and the source’s ability to provide a minimum of 1,000 gpm. Whether from a hydrant or a draft, 1,000 gpm is the standard to meet. An engine company with at least three personnel is ideal, even from a hydrant. If you are drafting, make sure the engine has enough suction hose to reach the water and that the crew is experienced with drafting. Drafting is easy—the pump and primer do all the work. Troubleshooting a draft takes knowledge and experience (photo 6).
7 An appliance set up to drain 5-inch hose and still capable of filling dual 2½-inch hose. (Photo by author.)
8 Using cam locks is a big time saver compared to threaded couplings.
Different tankers have different fill routes. Some use dual 2½-inch intakes, some 4- or 5-inch storz. No matter what the avenue for filling, the fill site needs to be prepared to handle all of them, and quickly. Five-inch storz ports are great and allow for rapid filling; however, some have no drain valve or, if they do, it’s often very small. This means that when trying to disconnect a filled 5-inch section of hose that is perpendicular to the ground, it is a very difficult and not efficient task. So, use various appliances to rig and create a relief valve that can rapidly drain that water and pressure (photo 7).
Fill sites need to have a clear approach and departure lane as well. The site should be set up so that two tankers can be engaged simultaneously—one actively being filled and another with connections made, waiting to be filled. One person positioned at a manifold can turn off the full tanker and immediately turn on to the next one. The full tanker departs and the next one moves up and gets connected, waiting to be filled. Fill sites should operate like race car pit crews. We don’t encourage tankers to “drive faster” to get more performance out of our shuttle. What we can do is streamline the fill sites and dump sites. Every few seconds you can shave off here and there translates into minutes saved. Minutes saved translates into gpm increases (photo 8).
Routes. Shuttle routes are often overlooked and can create some of the biggest obstacles to an efficient shuttle. Shuttle routes are ideally circular in nature. The fewer turns, stops, and starts and backing or repositioning that the tankers have to make, the better. Choose routes that are safe and, if at all possible, do not involve heavy traffic areas or traffic lights that they aren’t turning right at. Use law enforcement and create continuous lanes of travel that restrict any civilian traffic. Watch out for time of day.
We once were running a shuttle that started in early afternoon and then, at midafternoon, two school zones became active in our route. The shuttle bottlenecked and the scene flow was reduced as a result.
If at all possible, try to anticipate what traffic patterns are doing not only at the time you start but during extended operations. Account for dirt roads, bridges, and overhangs that may restrict movement. The shortest distance may not amount to the fastest travel time. Try to avoid tankers making three-point turns, as most tankers have a horrible turning radius so a three-point turn may in fact be a six-point turn.
Essentially, the common theme for a tanker shuttle is efficiency. Try to make every transaction that the tankers make as efficient as possible. The best way to do this is appliances and training. Find and use the right appliances, from the low-level strainers to jet siphons, manifolds, siamese, gates, floating strainers, adapters, cam locks, and so on. Since a tanker shuttle is going to be a mutual-aid event, you have to be able to mechanically interact with the responding departments both to fill and received the water from their tankers. Training is also essential. Exercising these skills is the only way to be able to perform them at a fire.
Standard operating procedures (SOPs). Have SOPs that outline what to do and when. Without a clear understanding of how these systems work and when to deploy one vs. the other, it will lead to confusion and chaos when various apparatus start to show up. The department needs to establish the framework for these systems so that all responding units and personnel know exactly what to do and how to do it. Assigning a water supply officer (WSO) at the onset of an event is a must to orchestrate the movement and positioning of the various assets. The WSO should acquire a dedicated channel for water supply and will bring in units to accomplish the goals of NFF as set by the incident commander.
Rural water supply is becoming a reality in our districts and communities. The ability to perform is not inherent to us and is a different animal than we are accustomed to, having been spoiled with municipal water supplies readily at hand. We have to study and rethink what we know and how we use our equipment and personnel on a fire scene. As our communities stretch into rural areas, simply building stations and putting an engine and staff in them will not solve this problem. More often than not, these crews and apparatus are equipped with tactics and equipment based on the firefighting that we have been doing in an urban setting. So, the personnel are improperly trained, and the apparatus are ill-equipped to handle any rural event that stretches beyond the capability of their tank water.
The good news is that this is a manageable problem. Your department may not have the budget to completely reoutfit its rural engines; however, the purchase of a few key items (suction hose and floating strainers) will drastically change your ability to capture rural water. Follow that with some training specific to drafting and transporting this water, and you can increase your ability to effectively and efficiently establish a sustainable fire attack in a rural setting.
Kyle Dent is an 18-year veteran of the fire service and is an engine lieutenant and the designated water supply officer for North Port (FL) Fire Rescue. He designed, developed, and implemented the department’s Driver Engineer Program as well as the Alternative Water Supply Strategy and Tactics plan. He is a Florida state certified fire officer, fire instructor, live fire instructor, and driver/pump operator.
