Waste or treasure?

How do you see your street sweeper debris?

Robert L. Wagner
Public Works Director
City of Yuma, Arizona

Tons of debris, including metals, wood, plastic, paper, etc. are swept off our streets each year. Along with it, in many parts of the country, huge amounts of soil and sand are picked up. In some areas, such as the southwestern deserts, this consists primarily of wind-blown dust and sand. In other areas it may be sand deposited from winter snow and ice operations.

In Yuma, Arizona, a small group of sweeper operators and street maintainers in the City's Public Works Department noted that most of the 3,600-plus tons of debris going to the landfill was just soil and sand. Like many areas throughout the country, reduction of landfill use is a major concern. Our landfill operations were facing the prospect of moving to a location that would force much higher transportation costs on the City. Anything we could do to reduce the amount of debris being hauled would be a direct savings to our budget.

The City had recently initiated a new program to flatten the organizational structure and encourage and empower employees to find better, faster, and less expensive ways to serve its customers. These employees decided to pool their talents and experience to see if their idea would hold water.

While visiting with the marketing representative of an equipment supplier, the team asked if it would be possible to have an onsite demonstration of a portable screening machine. The test would be used to determine the amount of usable sand and soil that could be recovered. They would also be able to evaluate the condition of the soil and its potential for reuse. The company agreed and the test was performed. The result showed that 96 percent of the sweeper debris was found to be usable fill material.

The next step was to have the City's Environmental group check the fill for contamination and suitability for use in various public works projects. There was some concern that pollutants such as petroleum products or agricultural chemicals could have been spilled or blown onto the streets and residue may still be present. After some research and testing, it was determined that the soil was sufficiently clean for use in routine pothole and other street maintenance operations. The wind, sun, and high temperatures encountered in this part of the country tend to speed the dissipation of contaminants from loose soil.

The team then calculated the probable savings based on landfill tipping fees and other disposal costs. The 96 percent reduction in volume resulted in a projected savings of $98,800 for the first year. Purchasing the Screen-All machinery would cost $58,181. The expected result would be a first-year savings of just over $40,000. Amortizing the equipment cost over a longer period would realize even higher annual cost avoidance. Each subsequent year could be expected to net about $100,000.

Subsequent accounting audits have verified much larger savings than originally predicted. This is based on a doubling of tipping fees as well as rapid growth of the City that has resulted in a dramatic increase of street mileage due to annexations. The tons of debris per year are much higher than those originally studied. The savings have been used to help purchase a new street sweeper to support growth and to fund an employee gain-sharing program in addition to the purchase of the screening unit.

When the original proposal was made, it was presented to the City administration for approval to implement. When it became apparent that the idea was successful, the team submitted it to the Arizona Clean & Beautiful Program for a Governor's Pride Award. It so impressed the judges that it was awarded and the three team members were publicly acknowledged for their initiative and efforts to improve our environment.

In addition, the City of Yuma has initiated a Gain Sharing Program to reward efforts such as this and many other innovative ideas that have emerged from the workforce.

There have been many winners in this story. Obviously, the three-member team has profited and garnered recognition. The City has benefited tremendously from the realized savings. The citizens enjoy their clean streets. The landfill volume has been reduced. And our whole community looks better and feels better about its image.

For more information, please contact Robert L. Wagner at 520-783-1287 or at pubwrks@primenet.com.