Rural Water Shuttle Operations – Part 2: Dump Site Operations

In a water shuttle operation, the opposite end from the fill site is the dump site. The dump site is located close to the incident, and its goal is to provide a continuous source of water supply to the apparatus attacking the incident. A variety of methods can be used to run a dump site, as well as a variety of methods that may be employed to discharge water from the tender. As with fill site operations, we mention a number of these methods, but focus on those that are generally recognized as the most efficient for long-term, high-volume water shuttle operations.

Dump Site Primary Operational Methods

Three primary methods can be used to operate a dump site:

1. Direct pumping operations.
2. Nurse tender operations.
3. Portable water tank operations.

Direct pumping operations. The direct pumping method involves having a tender pump the water from its tank directly into the fire pump of the attack pumper. This method is typically accomplished by having the attack pumper lay out a supply line that ends in a location that is easily accessible to the tenders approaching the scene. When the tender arrives at the dump site, the supply hose is connected to a discharge on the fire pump of the tender (Figure 1). The contents of the tender's water tank are then pumped to the attack pumper. In some cases, a siamese is placed at the dump site that allows two tenders to pump into the supply line.

The only real advantage of the direct pumping method is that it reduces the need for the tender to drive up small roads or driveways to park directly next to the attack pumper before pumping its water to it. The disadvantages of this method are many. It is very difficult, if not impossible, to provide a constant supply of water to the attack pumper. There will always be an interruption of flow when tenders are disconnecting and connecting. It requires every tender to have its own onboard fire pump.

Tenders that have small-capacity pumps or no pumps at all are basically useless if this method is employed. Tenders with small-capacity pumps may not be able to supply water to the attack pumper at the same rate the attack pumper is discharging water on the fire.

Nurse tender operations. This method generally involves a very large tender that parks immediately adjacent to the attack pumper. The attack pumper is supplied by a discharge line from the pump of the nurse tender or drafts directly from the tank of the nurse tender. Departments that use tractor-trailer tenders typically use them in this manner, as they are highly ineffective as shuttle apparatus in most cases.

The primary advantage of this method is that in many cases the nurse tender itself is so large that the fire is controlled before there becomes a need to refill its tank. There are several disadvantages to this style of operation. Once again, every shuttle tender is required to have a sizable fire pump in order to pump its load into the nurse tender. Even with a sizable fire pump, the dumping time for each tender is significantly higher than if it was able to discharge through its large-diameter direct tank discharge (dump) valve.

Portable water tank operations. The most efficient way of operating a water shuttle is to use portable water tanks as the dump site supply source. When using this method, one or more large portable water tanks are positioned in a strategically sound location near the emergency scene (Figure 2). Dump site location selection was discussed in Part 1.

Once the tanks are positioned, a pumper - called the dump site pumper - deploys hard intake hose with a low-level strainer into one of the tanks and prepares to draft water from the tank. When the first tender arrives on the scene, it discharges its water into the portable tank. The dump site pumper may then begin drafting from the tank and supplying water to the attack pumper. In some situations, the dump site may be located directly adjacent to the scene and the attack pumper may draft from the portable water tank.

This method does not require shuttle tenders to be equipped with a fire pump, as long as they have an adequate-sized direct-tank discharge valve, herein referred to as a "dump valve," and adequate venting. This method is also the easiest of the three methods to ensure a constant supply of water to the attack pumper, although no method is foolproof if not operated properly. The primary disadvantage of this method is that if a multiple-tank operation is to be employed, a substantial amount of working space is required for the dump site.

Water Tender Discharge Methods

Water may be unloaded from a tender to the dump site in three basic ways:

• 1. Using a pump on the tender.
• 2. Using a dump valve.
• 3. Pumping and dumping simultaneously.

Tenders may pump their water into a portable tank (or nurse tanker) through one or more discharges or hoselines. This should only be done when the tender is not equipped with a dump valve.

In general, it is not possible to pump water out of the apparatus as fast as a dump valve empties the tank. The limiting factors are flow capacity of the tank-to-pump lines, pump size, venting capability and the ability to control hoselines at the delivery point. In addition to the longer amount of time required to empty the tank, this method also requires that the tender driver/operator place the fire pump in gear before discharging water and that he takes it out of gear before heading back to the fill site. Both of these factors increase the overall time spent at the dump site.

If this method is used, some type of mechanical device must be used to hold the hoses that are discharging into the tanks. Commercial or homemade clamps or fill spouts are available. Some jurisdictions choose to tie a section of hard intake hose to the portable tank and connect the fill lines to it. Any method is suitable, as long as firefighters are not required to manually hold the lines.

The most efficient method of unloading tankers is to dump the water into portable tanks through a gravity or jet-assisted dump valve (Figure 3). Dumping, with sufficient portable tank capacity, allows tankers to deliver their water rapidly and get back on the road. The actual amount of flow through the dump valve is dependent on the design and size of the dump valve, the baffling in the tank and the venting capability of the tank. Baffles must have sufficiently sized openings to allow free water movement at the bottom of the tank and air movement at the top during rapid filling or unloading. National Fire Protection Association (NFPA) Standard 1903 requires all tenders to be able to dump at a minimum average flow rate of 1,000 gpm for the first 90% of the tank. It is most desirable for the apparatus to be able to dump off either side and the rear of the truck.

In theory, an apparatus equipped with both a fire pump and dump valve could simultaneously pump and dump its load at the same time. In reality, this is not a very timesaving operation. The time spent engaging the fire pump and making any connections necessary for the pumping portion of the evolution generally negates any time advantage that might be gained. It is better to simply use the dump valve on apparatus that also has a fire pump.

Operating The Dump Site

As stated earlier in this article, the most efficient method for operating a dump site is to have tenders dump their loads into one or more portable water tanks. A dump site pumper is responsible for drafting from the portable tank and supplying water to the attack pumper. Most jurisdictions find this to be the optimum way to provide a constant high flow of water using a shuttle operation.

Single portable tank operations. The simplest form of a dump site operation is one in which a single portable water tank is used. In this case, the tenders dump their water directly into the tank from which the dump site pumper is drafting (Figure 4). A single portable tank works on fires that require relatively low overall flow rates (less than 300 gpm). The portable tank and the dump site pumper must be positioned so that easy in-and-out access is allowed for the tenders that are dumping into the tank.

The most common style of portable water tank is the folding type. This tank is removed from its storage position on the apparatus in much the same manner as a ground ladder would be removed. It is then carried to its deployment position and simply unfolded. Portable tank drains should be tucked inside the tank to prevent leakage or dislodging. Some departments choose to place a salvage cover on the ground beneath where the tank is deployed. This saves wear on the portable tank liner. Several other types of portable water tanks may be used in some jurisdictions. One type comes in several sections that must be assembled at the scene. Once the metal framework is assembled, the liner is attached to it and flaked out around the tank. When totally assembled, this type resembles the folding type previously described.

Yet another type is the self-supporting or frameless portable tank. This tank is a large bladder that has a floating collar around the opening. As water enters the tank, the collar continues to rise until the tank is filled. This style of tank has an intake hose connection in the bottom of the tank from which drafting may be achieved.

Regardless of the style of portable water tank that is used, it is recommended that the portable water tank have a capacity that is at least 500 gallons larger than the capacity of the water tank on the apparatus carrying it. This allows the apparatus to dump its entire load into the tank, even when on a slight incline or a road with a high crown.

The dump site pumper should have a low-level strainer attached to the hard intake hose. This allows continuous drafting ability down to a point where only about two inches of water is left in the tank (Figure 5). Low-level strainers that are designed for use in portable tanks are commercially available or may be homemade.

Once the tank has been deployed, the first tender may dump its load of water into the tank. A dump site spotter or the dump site officer should wave and guide the tender into position. Adequate guidance must be given to assure the tender driver/operator that the dump valve is properly aligned with the tank.

When the tender is in position, the dump valve is opened, and water flows into the portable tank. Once the level of water in the portable tank is sufficient for drafting, the dump site pumper should prime its pump and start water flowing. It is recommended that the dump site pumper flow a booster line back into the portable tank or use some other type of waste line arrangement to ensure that prime is not lost when other discharge lines are shut down.

Once the first tender has emptied the contents of its water tank into the portable tank, it should immediately proceed to the fill site to reload. If there is still space available in the portable tank, the next tender should be brought into position and its water should also be dumped into the portable tank until it is filled.

If the second tender is not able to empty its entire load before the portable tank is full, it should remain in position and empty its tank when room in the portable tank becomes available. Additional tenders should be staged and ready to proceed to the portable tank as soon as their water is needed to refill the tank.

Multiple portable tank operations. Incidents that require flow rates in excess of 300 gpm are best served by a multiple portable tank dump site operation. The number of portable tanks that may be used at a dump site is limited only by the number of tanks and the amount of water transfer equipment available at the scene. In reality, the most common multiple portable tank operations used in most jurisdictions range from two to five portable tanks.

When multiple portable tanks are used, each of the tanks is positioned so that water may be transferred from one tank to the next. The ultimate destination of the water in all the tanks is to be routed into the last tank, from which the dump site pumper is drafting water that is being supplied to the attack pumper (Figure 6).

The basic goal of the multiple tank operations is to keep the final tank in the chain, from which the dump site pumper is drafting, full at all times. Water is constantly being transferred from the preceding tanks in the operation to achieve this goal. When this is done, the upstream tanks empty first and are available for dumping without delay.

There are a number of methods for transferring water between tanks. The simplest method is to connect two tanks by their drain openings. However, because most commercially constructed tanks only have one drain, this limits you to a two-tank operation. Using this method maintains the same level of water in both tanks at all times. In general, this method is discouraged by most authorities on water shuttles.

The most efficient method uses jet siphons to move water from one tank to another. The jet siphon is a device that is attached to either a section of hard intake hose or a piece of PVC or aluminum pipe (Figure 7). The jet siphon has an inlet for a 11/2-inch or larger hose to be connected to it. When the jet siphon, hard intake hose, and 11/2-inch hose are assembled, the end with the jet siphon is placed into the tank from which water is transferred. Once that tank has a sufficient amount of water in it, the 11/2-inch hose is charged. As this flow of water begins through the hard intake hose, water from the portable tank is also drawn in. All of this water flows through the hard intake hose and into the next tank in line (Figure 8). If the next tank becomes full, the 11/2-inch line is shut down to stop the flow.

Care must be taken to ensure that water remains in the apparatus water tank at all times. If the apparatus water tank runs dry, the pumper is not able to supply the jet siphon if the drafting tank becomes empty and pump prime is lost.

If only two or three tanks are going to be used in conjunction with a jet siphon operation, the dump site pumper should be able to supply the hoses to the jet siphons. This requires a little more work on the part of the dump site pumper driver/operator, but it is not unreasonable. If four or more tanks are to be connected using jet siphons, it is advantageous to have a second pumper draft from the tanks solely to supply some or all of the jet siphon lines.

The procedure establishing and running a multiple portable tank shuttle operation is as follows:

• Step 1. The first portable tank is deployed in the same manner as described previously in the single tank operation section. Make sure that the tank drain is on the downhill side of the tank.
  
• Step 2. The dump site pumper driver/operator and crew deploy their hard intake hose and strainer into the first portable tank.
  
• Step 3. The first tender on the scene dumps its water into the first tank. The dump site pumper may then begin the drafting operation.
  
• Step 4. A second portable tank is set up next to the first one. A tip-to-tip diamond array is generally the preferred method for arranging the tanks (Figure 9). If immediately available, use different colored portable tanks to help the dump site officer direct apparatus to the appropriate tank for dumping. However, this is not so crucial that you should wait for a different color tank to arrive on the scene. Whichever tanks are available should be deployed as quickly as possible.
  
• Step 5. The jet siphon equipment is assembled. The end with the siphon is placed in the second portable tank, and the discharge end of the assembly is positioned over the edge of the first portable tank and secured.
  
• Step 6. The next tender dumps its load into the second portable tank. Once the water level is sufficient, the jet siphon supply hose is charged to begin the process of transferring water from the second tank to the first.
  
• Step 7. If additional portable tanks are desired, each tank should be set up and operated as was described for the second tank in Steps 4 through 6. Tenders should always dump into the end-most tank that has room for water. The dump site officer should advise the tender driver/operator of which tank to dump in as he positions the apparatus.
  
• Step 8. The dump site pumper driver/operator or jet siphon pumper driver/ operator should monitor the level of water in each tank and adjust the siphon lines accordingly.

The dump site officer should monitor the ground conditions around the dump site as operations proceed. It is inevitable that a significant amount of water will be spilled in this area.

During freezing conditions, ice may begin to form. It may be necessary to have sand or road salt brought in to improve the road conditions. If the road is not paved, it may begin to become soft. In some instances, it may be necessary to relocate the dump site if this occurs. However, this has a significant negative impact on the fireground operation if this becomes necessary.

If all the portable tanks become empty at some point during the operation, the dump site pumper may continue to support fireground operations using water that is in its onboard water tank. When this becomes necessary, firefighters in hazardous positions should be withdrawn as loss of water to attack lines may be imminent. Once the portable tanks are refilled, normal operations may resume. The driver/operator of the dump site pumper should refill the apparatus water tank as soon as possible.

Shutting Down The Dump Site

Once the need for a continuous water supply is no longer present, the dump site operation may be disbanded. Before disassembling the operation, it is generally a good idea to make sure that the attack apparatus and dump site pumper have topped off their onboard water tanks. This is because often a little more water is required for overhaul operations.

When the apparatus tanks are full, all the drafting and water transfer equipment can be disassembled, cleaned and stowed. The portable tank drains may be opened to allow the remaining water to drain out. If there is a lot of sediment or debris left in the tank(s), it should be rinsed out before stowing on the apparatus.

Any tenders that were staged in preparation for dumping may be returned to service or used in any other manner the incident commander deems appropriate. In some jurisdictions, one full tender is left at the scene with the attack apparatus to provide sufficient water for extended overhaul operations or to provide attack capability in the event of a major flare-up.

Conclusion

Effective water shuttle operations do not just "happen." They occur as a result of proper planning and training. No jurisdiction should expect to pull off a perfect water shuttle after reading one article. However, these principles when put into place over a period of time will surely allow for more efficient water shuttles to occur.