The containment mat, a Latimat Containment Pad, is distributed by Environmental Cleaning Systems, Inc. (figure 6). The rubber mat is 19 feet wide and 33 feet long. Cylindrical pieces of foam are inserted into sleeves along the sides of the mat, forming raised sides (3 inches high) that contain the wash water. A reel has been fabricated and mounted on the back of the trailer to make the mat easier to set up and store.

Figure 6—A 19- by 33-foot mat keeps the wash
water where it can be recycled. Foam tubes are
placed in slots along the mat's edges to create a
3-inch lip on all sides. The mat shown here was set
up at the Cathedral Fire near Darby, MT, during
August 2002. The wash water drains to the lower
right corner of the mat, where a sump pump
draws water for filtering and reuse.

The mat is very durable, but users should ensure that sharp debris is not underneath it. Rubber-tired vehicles probably will not puncture or rip the mat unless the mat is placed over an extremely sharp object. A felt liner the same size as the mat helps protect the mat from cuts or punctures. The liner, stored in a box on the trailer, is unfolded on the ground before the mat is unreeled.

Tracked vehicles, such as dozers or small excavators, require special attention. Place industrial strength conveyor belting under their tracks to prevent them from damaging the mat. Long vehicles, such as school buses, also require special handling. Typically, half of the vehicle is driven on the mat and washed, then the vehicle is moved to wash the other half.

Patching material that comes with the mat can repair punctures or holes. The patching material is the same material as the mat and can be cut to any size. The patch is applied to the mat by heating the edges with an industrial heat gun, melting the patch to the mat.

Water is stored in a 550-gallon tank mounted on the trailer (figure 7). A high-pressure, high-volume diaphragm pump (figure 8) supplies water to the underbody washer and wands at a pressure of 800 pounds per square inch and a flow of 20 gallons per minute. The diaphragm pump is powered by a 25-horsepower, two-cylinder gasoline engine. A 40-micron strainer between the tank and the pump prevents particulate from damaging the pump.

Figure 7—A 550-gallon tank is the main storage tank that supplies
water to the washer.

An overflow bypass valve (figure 9) protects the pump. Between washings, when no water is needed, the valve routes unused water back to the holding tank to prevent damage to the pump. The valve is one of the few consumable parts of the washer. The internal stainless steel seats can wear if the wash water contains a lot of grit or fine particles. As the seats wear, pressure to the wands and underbody washer will decrease, because water will be diverted continuously to the main holding tank.

Figure 8—A high-pressure and high-volume diaphragm pump pro-vides water to the wash wands and underbody washers. A 25- horse-power, two-cylinder engine powers the pump.

Figure 9—A bypass valve directs water back to the holding tank when water is not needed for the wands or underbody washers. This valve will prevent damage to the pump, but its internal parts can wear and require replacing. Hydraulic fittings make the valve easier to replace.