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==Cost information== | ==Cost information== | ||
− | + | Data compiled from the [https://stormwater.pca.state.mn.us/index.php?title=Case_studies_for_street_sweeping case studies in this manual] are illustrated in the adjacent table. The median cost per curb mile is $94 while the mean cost is $487, showing the wide variation in cost information. The cost information provided by the cities typically does not include equipment costs but typically does include disposal costs. | |
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+ | Three cities from the case studies (Mankato, St. Cloud, Roseville) reported information on mass or volume of material collected. We used the [[Street Sweeping Phosphorus Credit Calculator]] to estimate cost per pound of phosphorus removed. We used the wet mass method and calculated values for fall and for the remainder of the year. | ||
+ | *Mankato: Cost ranged from $293-408 per pound of phosphorus | ||
+ | *St. Cloud: Assuming a bulk density of 0.11 kg/L for material collected, cost ranged from $174-243 per pound of phosphorus. The City estimates the cost as $195-246/lb-P over a period of four years, with a median cost of $226/lb-P. | ||
+ | *Roseville: Cost ranged from $85-119 per pound of phosphorus. The City estimated $193/lb-P in their calculations. | ||
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+ | The City of Prior Lake and University of Minnesota researchers conducted [https://stormwater.pca.state.mn.us/images/5/5e/Prior_Lake_Street-Sweeping-Study_final-9-24-2014.pdf an intensive study of street sweeping in Prior Lake] (Kalinosky et l., 2014). This study included a literature review of other sweeping studies. Cost per mile swept was computed on a monthly basis and ranged from $20-29 per mile. This is similar to the cost data reported by Mankato and St. Cloud, which were the two best documented case studies. Cost effectiveness of sweeping was $41-lb-P in October, less than $100/lb-P during March, April, October, and November, and $400-600/lb-P in the summer months. | ||
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+ | A discussion of cost consideration can be found [https://stormwater.pca.state.mn.us/index.php?title=Recommended_street_sweeping_practices_for_water_quality_purposes#Cost_considerations at this link]. | ||
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Overview, water quality benefits, and other co-benefits of street sweeping
This page provides an overview of street sweeping and a discussion of water quality benefits and co-benefits of street sweeping.
Street sweeping (also called street cleaning) refers to removal of sediment, litter, or other accumulated substances on roadways, particularly in urban and suburban areas. Street sweeping does not include removal of large quantities of leaves brought to the street/verge for removal, large debris or bulky items; removal of these items is typically handled by large vacuum leaf collectors or dump trucks, respectively.
Historically, street sweeping was conducted manually by a sanitation worker with a broom or shovel to remove animal waste from horse-drawn vehicles and other detritus on roadways. Mechanical sweepers such as broom systems attached to horse carts came about in the mid-1800s, and in the early 1900s street cleaning wagons sprayed water onto roadways to wash away debris. Motor-driven street sweeping vehicles were patented in the US in 1917.
Modern street sweeping has improved efficiency of debris removal from roadways dramatically. The focus of street sweeping was simple large “cosmetic” debris removal until the 1970s when concerns about water quality arose. In the decades following, improvements in street sweeping technology focused more on the removal and collection of coarse sand particle-sized street dirt, and smaller particles which contribute to instream sediment and nutrient pollution when swept off of or washed into waterways. Even when a street was cleaned of large refuse, the amount of tiny particulate matter that could not be effectively removed manually remained to wash-off into waterways following precipitation. Pollutants in stormwater runoff have long been recognized as contributors to aquatic habitat degradation, nuisance algal growth, low dissolved oxygen and toxicity in receiving water bodies . More recently, there has been a focus on street sweeping to remove the organic matter produced by street trees (leaves, seeds, flowers, etc), which can contribute significant amounts of phosphorus to runoff, especially in the fall during leaf drop. Particulate matter (air) also poses significant air-quality concerns when entrained in the air due to wind.
Roadways accumulate debris and material such as sediment, vegetation, vehicle debris/waste, industrial emission particle deposition, and litter. Harmful pollutants which accumulate on roadways, parking lots, and pavement include metals, organics, nutrients, and particulate matter, which street sweeping helps remove. The effectiveness of street sweeping for removing specific pollutants depends on the timing and methods of sweeping, including season, frequency of sweeping, timing relative to runoff events, type of sweeper(s), sweeping practices such as speed of sweeper and vehicle parking, and the characteristics of the surface being swept (land use, surface roughness, etc.). Below is a qualitative summary focused on pollutant and sweeper type.
For more information on stormwater and pollutants in stormwater, link here.
Street sweeping provides several benefits in addition to water quality improvement. The most cited co-benefits include improved appearances (aesthetics), improved roadway safety, potential reduction in flooding associated with clogging of stormwater conveyance systems, and reduced air pollution. Many key benefits associated with street sweeping have cumulative impacts as well. For example, increased removal of fine particulate matter can reduce the sediment load to downstream BMPs, extending the life of these practices which provide improved water quality further downstream.
Cost and maintenance information for street sweeping for water quality
Information on cost and maintenance for implementing a street sweeping program is variable. This is due to several factors, including but not limited to equipment cost and maintenance, frequency of sweeping, operator skills, and disposal methods.
Data compiled from the case studies in this manual are illustrated in the adjacent table. The median cost per curb mile is $94 while the mean cost is $487, showing the wide variation in cost information. The cost information provided by the cities typically does not include equipment costs but typically does include disposal costs.
Three cities from the case studies (Mankato, St. Cloud, Roseville) reported information on mass or volume of material collected. We used the Street Sweeping Phosphorus Credit Calculator to estimate cost per pound of phosphorus removed. We used the wet mass method and calculated values for fall and for the remainder of the year.
The City of Prior Lake and University of Minnesota researchers conducted an intensive study of street sweeping in Prior Lake (Kalinosky et l., 2014). This study included a literature review of other sweeping studies. Cost per mile swept was computed on a monthly basis and ranged from $20-29 per mile. This is similar to the cost data reported by Mankato and St. Cloud, which were the two best documented case studies. Cost effectiveness of sweeping was $41-lb-P in October, less than $100/lb-P during March, April, October, and November, and $400-600/lb-P in the summer months.
A discussion of cost consideration can be found at this link.
City | Annual cost ($) | Curb miles swept | Cost per curb mile |
---|---|---|---|
Lakeville | 246000 | 1200 | 205 |
Mankato | 400000 | 11814 | 34 |
Rochester | 80000 | 11000 | 7 |
St. Cloud | 70000 | 1825 | 38 |
Bloomington | 850000 | 342 | 2485 |
Fridley | 225000 | 1500 | 150 |
Costs typically do not include sweeper replacement cost |