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Surveys From's 'Sweeping as a BMP' Seminars Provide Insight Into California Sweeping Programs

The survey results from's May 2006 seminars showcased how California cities and other agencies are currently sweeping.

by Ranger Kidwell-Ross

In May of 2006, the first seminars in recent times that were exclusively dedicated to discussing the effectiveness of sweeping as a Best Management Practice (BMP) for stormwater pollution runoff were held in the L.A. and San Francisco areas of California.

Sponsored by, and co-sponsored by Allianz/Madvac, the seminars were designed to assist decision-making by state and local administrators charged with reducing the amount of pollution in the state's storm water runoff. As seems so often the case, California has taken the lead in taking action designed to reduce runoff pollutants.

At each of the seminars, held in at the Orange County Fairgrounds and in San Jose, respectively, a survey form was distributed to attendees. Those who directly represented a city or other agency that conducted, or contracted for, sweeping were asked to fill out the survey. A total of 15 completed surveys were returned for each location. Below are screenshots showing the results of both surveys.

Seminar attendees were asked to list how often the organization they represented swept each of a variety of areas. These included:

  • Residential
  • Arterial Streets and Highways
  • Central Business Districts
  • Industrial Areas
  • Parking Lots

They were additionally asked to list whether or not they had any type of program that sifted or otherwise made a secondary use of sweeping debris, and whether or not they required cars to be removed prior to sweeping.

Considering that California is probably leading the way toward developing BMP standards for reducing stormwater runoff pollution, my analysis of the survey is that there's a great need for additional education about what sweeping can do for pollution removal. Following are the 'high points' of that analysis, starting from the top of the survey information.

Good was that 23 of 30 respondents cite their city as sweeping residential areas at least monthly. However, a surprising 23% of the total do so with a mechanical broom sweeper. Since broom machines don't pick up fines as well as air sweepers and cost more to operate, cities that use broom sweepers on a routine basis for residential sweeping should at least evaluate that decisionmaking process. Since most residential areas would stack up little debris in even a month, unless there is some type of debris that tends to clog intake tubes with a high frequency air sweepers would seem to be the better choice.

I also found it surprising that 43% of the cities are sweeping arterial streets and highways on a weekly basis. Anecdotally, I think this is significantly higher than the national average. For this process, the choice between air sweepers and broom machines is pretty evenly split.

Only 2/3 of respondents cite sweeping their Central Business District on at least a weekly basis. Since it is becoming increasingly difficult to keep a healthy downtown core, with the pressure from outlying malls and box stores, one of the best ways to keep a CBD looking presentable is via sweeping. Especially now that small sweepers like Allianz's Madvac line and Applied Sweepers' Green Machines are now available in the U.S., it has become easier and cheaper than ever to keep downtown areas sparkling.

It was good to see that just over 25% were sweeping their industrial sectors on a weekly basis, with just under 50% reporting a sweeping frequency of at least monthly. Those waiting longer than that need to realize that their industrial areas may well be one of their last large-scale sources of non-point pollution runoff. Plus, the chemicals and metals from these areas can be quite nasty.

Since many types of industrial production are still not covered under the Clean Air and Water Acts -- and since some of those mandated under the Acts are not in compliance -- there is typically no requirement for cleaning frequency for the company parking lots. Unlike with shopping centers, where cleanliness is usually maintained in order to keep shoppers happy, that's not the case with industrial parking lots. As a result, runoff from industrial facility parking areas can potentially be a major pollution source.

Although only 14 of the participants knew what type of sweepers were used for industrial sweeping, eight of those were broom machines. Because a highly disproportionate percentage of pollutants are found in smaller material -- up to 80% of EPA-targeted pollutants on a typical street are found in the 25-to-60% of the total that are sized 250 microns or smaller -- except in unusual circumstances an air sweeper is probably a better call for industrial sweeping.

It was good to see an awareness of the need to keep parking lots clean, with half cleaning on at least a monthly basis. However, the higher level of broom sweepers shown as being used for that purpose may be a reflection of cities using the big broom machines they have for a non-standard usage in a parking lot.

Unless these cities are actually using small ride-on or walk-behind sweepers for this purpose, they probably would be better off to purchase a smaller air machine to do the job. Alternatively, they might well find it a better value to contract out that part of their city's sweeping needs.

Another area open to improvement is finding ways to reduce the waste stream from sweeping. Only two attendees noted their cities as utilizing sifting or other reuse options for debris picked up while sweeping. Since sifting can offer up to 70% reduction in landfilling amounts, as well as offering other environmental benefits, this is clearly an option worthy of more investigation.

The final category also offered a surprise, especially since pollution runoff from streets is such a relative hot button in California. About half of the cities responding to our seminar survey are not even requiring cars to be moved during sweeping.

Although sometimes a political 'hot potato,' this is an action that can provide immediate pollution reduction benefits. In the seminar, it was clear that many managers had not thought through the fact that each car parked on the street during sweeping actually represents about three car lengths that go unswept. That's because it takes the sweeper about a car length to swing around a car, with another required to get back to the curb.

If reducing non-point pollution runoff is, indeed, a serious factor to an agency, it is vitally important that parking restrictions are put into place. Many cities doing so have discovered that fines will more than pay for their sweeping programs.

If you have questions or comments about any of the analysis shown above, I invite you to contact me via email sent to, or by calling 360-724-7355.

You may find it helpful to download the PowerPoint presentation used at these seminars. It was developed by Roger Sutherland, co-presenter and President of Oregon-based Pacific Water Resources. Sutherland's contact info is; phone 503-671-9709, ext. 24.

Bay Area Survey Results

Orange County Survey Results

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