How often should streets be swept? What is the best frequency for a particular community? Well, it depends. The most obvious factors include:
- How dirty gutters become between sweeps;
- The acceptable level of cleanliness;
- What is affordable;
- What regulations require; and
- How well landscape irrigation can be controlled.
The reason cities sweep is seldom aesthetics, though at times cleanliness seems like the paramount goal. The main goals are to remove debris before it is flushed into storm drains and allow the easy flow of water to reduce algae and the liability of its slippery effects.
Gutters are the natural accumulation site for litter, leaves, landscaping material and dust and dirt that settle on the street from wind. Normal traffic movement blows 97 percent of the debris into gutters. This debris then sits in the gutter, blocking irrigation water flow and being tracked by cars into driveways and garages.
When it rains, debris is flushed into a storm drain system and can clog it—causing local flooding—or wash into bays and oceans. While flood control channels were never meant to be clean enough areas for swimming or fishing, taking reasonable steps to remove debris before it gets into the pipes and channels is worthwhile.
Consider the following factors when designing or tailoring a community street sweeping plan.
Gutters. How dirty gutters become between sweeps is the result of many factors, including irrigation runoff (wet gutters hold debris); age; street condition; landscape maturity and type; and littering habits of residents and motorists.
Cleanliness. The acceptable level of street cleanliness can cause debate among neighbors. Some items to consider include:
- How often do crews sweep the streets of neighboring cities to which a community in question is compared?
- Are the community’s gutters maintaining property values or detracting from them?
- If an algae-related slip and fall lands the community in court, have reasonable steps been taken to reduce algae?
- Do kids ride bikes or play in the street?
- Do low spots drain, or are they turning septic and odorous?
- Is debris from the street tracking into residents’ homes?
- Is lack of sweeping speeding up the need for costly street repairs or resurfacing?
Also, is the backed-up water in the gutter causing the sweeper to leave an unsightly stain? No sweeper can effectively handle water in the gutter without some staining. Coordinate the automatic timers or sweep to allow water to flow better.
Are sweeping results optimized? Frequency of sweeping has an effect on how clean sweepers can get a street, just as in landscaping if one lawn is mowed once a week and the other once a month. If both get mowed the same day, the weekly one looks better; the same applies to streets and sweeping.
Is enough of the street being swept? Most homeowners associations have some cars parked in the street. The sweeper will miss these areas, and that portion of the curb will go twice as long between sweeps. Assuming cars cause 10 percent of the curb to be missed each sweep and that it is a different 10 percent next service, 100 percent will be swept at least twice per month with weekly sweepings.
Do the streets meet personal tests? No matter what frequency is used, check the streets the day before the sweep. Of course they will not be clean, but are they acceptable based on all the above criteria? If so, sweeping frequency is sufficient. If not, increased frequency is in order.
Affordability. So many items compete for a community’s dollars. Fortunately, sweeping can be one of the smaller line items in a budget. Sweeping can also extend street life, reducing this major expense.
Keep in mind the savings for increased frequencies. Weekly sweeping is a 100 percent increase in service over twice per month, yet it may only cost 60 percent to 80 percent more. Higher frequencies have a lower number of parked cars. Staying off the street every Wednesday is easier to remember than the first and third Wednesday of a month, and sweeping only on the third Wednesday is almost impossible to remember. Fewer parked cars mean more of the gutter is swept, resulting in more value for funds spent.
Regulations. Thinking long term, sweeping at least weekly and installing expensive catch basin filters/trash catchers may be required. Meeting new storm water runoff regulations can be costly, but street sweeping is considered a best management practice and should be part of a community’s storm water runoff permit.
Landscape Irrigation. Controlling landscape irrigation to keep gutters dry on sweep day is the best thing a community can do to have clean streets. For communities that cannot (or think they cannot) reduce the water flowing into gutters from homeowner irrigation, sweeping more often will reduce debris flowing into storm drains and improve water flow in gutters. The flatter and wetter a street is, the more likely it is to need weekly sweeping.