Introduction

Noxious weeds, invasive plants, and harmful fungi pose an increasing threat to native ecosystems, croplands, and other plant communities throughout the United States. While weeds have long been recognized as a problem for agriculture, now their potential to harm other plant communities, including those in forests and wildlands, is receiving greater attention.

An estimated 2,000 species of invasive and noxious weeds (figure 1) are already established in the United States. All ecosystems are vulnerable to invasion, even those that are largely undisturbed.

Figure 1—Leafy spurge (left, by William M. Ciesla) and spotted knapweed
(right, by Jim Story, Montana State University) are just two of the weed species
whose seeds the MTDC portable vehicle washer can remove from fire vehicles.
— Photos courtesy of Forestry Images (http://www.forestryimages.org).

Land managers may use several methods to control noxious and invasive plants. These methods include chemical spraying, hand picking, and biological control. Prevention measures can help keep noxious and invasive plants from becoming established. For example, many States have implemented programs for certifying weed-free hay and straw for pack animals.

One measure that can help prevent the spread of weeds is to wash vehicles before they enter a weed-free area or when they leave an infested area. Weed seeds and fungal spores can be transported in the mud or dirt on vehicles. Firefighting vehicles can be deployed on fires throughout the country, giving them the potential to transport seeds to remote locations. Several Forest Service ranger districts and some contractors have assembled vehicle-washing systems that have been used to clean firefighting vehicles.

Some of these systems use high-pressure wands and nozzles (similar to those in a standard car wash) to wash the vehicles. Others use underbody spray systems to remove dirt and mud from the underbody of the vehicles. Because the wash water is not recycled, these systems use large amounts of water.

The Missoula Technology and Development Center (MTDC) was asked to design a portable vehicle-washing system that would:

• Wash a vehicle to remove dirt and mud deposits on the exterior of the vehicle in 5 minutes. The emphasis of the cleaning should be in the wheels, wheel wells, bumpers, and underbody of the vehicle where most mud and dirt collects. The washing needs to be done quickly so it does not slow down firefighting and other operations.
  
  
• Fit on a single trailer that can be towed by a ¾-ton pickup truck. The system should be small enough to be transported easily an should not take up a lot of space when it is deployed.
  
  
• Reuse wash water. This requirement should eliminate the need to constantly fill holding tanks or have a water supply at the washing site. Also, spores and seeds can be filtered from the wash water for disposal.
  
  
• Be operated easily by no more than two persons with minimal training.
  
  
• Be inexpensive to produce. Low production costs will allow forests, districts, and private contractors to purchase them.
  
  
• Wash vehicles ranging from lowboy trailers to all-terrain vehicles (ATVs).