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Residential Street-Dirt Accumulation Rates and Chemical Composition, and Removal Efficiencies by Mechanical-and Vacuum-Type Sweepers, New Bedford, Massachusetts, 2003–04

U.S. Geological Survey, Scientific Investigations Report 2005-5184

By Robert F. Breault, Kirk P. Smith, and Jason R. Sorenson

In cooperation with the U.S. Environmental Protection Agency, Massachusetts Department of Environmental Protection, and the City of New Bedford Department of Public Works


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Abstract

The U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency, Massachusetts Department of Environmental Protection, and the city of New Bedford Department of Public Works, examined accumulation rates and chemical composition of street dirt in residential areas in 2003 and 2004 and analyzed the effectiveness of two types of street sweepers. Street-dirt accumulation rates were determined on two streets within an area of predominantly multifamily homes in the city of New Bedford, Massachusetts. Accumulation rates were determined for 1-, 2-, or 3-day intervals; street dirt with particle sizes larger than 125 micrometers was collected; and finer material was flow-proportionally sampled. Chemical composition of street dirt was determined at the two residential locations from a handheld vacuum equipped with a 0.2-micrometer high-efficiency particulate air filter. Vacuumed material was analyzed for elements (including trace metals) and polyaromatic hydrocarbons (PAHs), which are contaminants typical of urban environments. Street-sweeper efficiencies were determined by applying a known mass of dirt to a street and measuring the mass of dirt swept by mechanical- and vacuum-type sweepers. Street dirt swept by the city in routine sweeping by both types of sweepers was analyzed for particle-size distribution, elements, and organic compounds, and these data were used to estimate the mass of contaminants removed from the city's streets.

Street-dirt accumulation rates ranged from about 2.1 to 41 grams curb-meter day with an average of 14 grams curbmeter day; about 56 percent of the material collected was coarse sand (gravel, fine sand, silts and clays combine to make up the remaining 44 percent). Residential street dirt had substantial concentrations of trace metals and PAHs. Trace metal and PAH (sum of parent PAHs) concentrations were generally greatest on fine-grained particles (less than 63 microns in size). Coarse-grained particles, however, generally accounted for the largest mass of the trace metals&cadmium, chromium, copper, lead, nickel, and zinc (about 30 percent) and sum of parent PAHs (about 27 percent), because of the greater mass of coarse-grained particles. Ratios of some PAHs measured in street dirt collected during this study were similar to those measured in other studies elsewhere and closely resemble those measured in asphalt and used motor oil. Street-sweeper efficiencies ranged from about 20 to 31 percent for the mechanical sweeper and from about 60 to 92 percent for the vacuum sweeper for the particle-size range tested. Efficiencies for particle sizes between 2 millimeters and 250 micrometers (or coarse sand) were at least 1.5 to 5 times greater for the vacuum sweeper compared to the mechanical sweeper. Data collected in this study indicate that New Bedford's street-sweeping program has successfully removed about 3.8 million kilograms of street dirt, which contains potentially toxic chemicals such as trace metals and PAHs that may otherwise end up in the city's catch basins, treatment plants, and rivers and streams that receive urban runoff. Results of this study can also be used in simulation models to analyze the effects of street contaminants and street sweeping on the quality of receiving water in other cities throughout the northeastern United States.

Table of Contents

Abstract

Introduction

Purpose and Scope

Previous Studies

Field Methods and Laboratory Analysis

Street-Dirt Accumulation Rates

Street-Dirt Chemistry

Street-Sweeper Efficiencies

Bias and Variability

Street-Dirt Accumulation Rates

Street-Dirt Chemistry

Metals

Polyaromatic Hydrocarbons

Street-Sweeper Efficiencies

New Bedford's Street-Sweeping and Contaminant-Load Reduction Program

Summary and Conclusions

Acknowledgments

References Cited

Figures

1. Map showing location of Query and Central Streets, street-dirt accumulation and chemical-composition study areas, in the city of New Bedford, Massachusetts

2–5. Photographs showing:

2. A, Query Street and B, Central Street, street-dirt accumulation and chemical-composition study areas, New Bedford

3. A, Street-dirt collection device installed in the Query Street catch basin; B, Query Street washing with the Vactor machine; C, collection of wash water with entrained street dirt as part of the street-dirt accumulation experiments; and D, equipment used to measure discharge and sample wash water, New Bedford

4. A, Pelican Series P mechanical sweeper and B, Johnston 605 Series vacuum sweeper, used in the evaluation of sweeper efficiencies

5. Street-sweeper efficiency tests. The process here was carried out on both types of sweepers. A, Precleaning of sweeper; B, dirt application; C, sweeping; and D, collection of swept dirt, as part of the street sweeping-efficiency experiments, New Bedford

6–9. Graphs showing:

6. Relation between street-dirt accumulation rates and average daily wind speed, New Bedford

7. Total recoverable concentration of selected metals and total polyaromatic hydrocarbons (sum of parent polyaromatic hydrocarbons) measured in street dirt, by particle-size range, New Bedford

8. Street-sweeper efficiencies measured for the Pelican Series P mechanical sweeper and the Johnston 605 Series vacuum sweeper, New Bedford

9. Estimated mass of selected metals and total polyaromatic hydrocarbons (sum of parent polyaromatic hydrocarbons) removed by street sweeping during 2004 by the city of New Bedford

Tables

1. Street-dirt accumulation rates and particle-size distribution for two streets in a predominantly multifamily area of the city of New Bedford, Massachusetts

2. Inorganic element concentrations by particle size measured in street dirt collected in an area of predominantly multifamily homes in the city of New Bedford

3. Hierarchy of the relative solubility of trace elements commonly studied in highway runoff

4. Polyaromatic hydrocarbon concentrations and ratios of selective parent and polyaromatic hydrocarbons by particle size measured in street dirt collected in an area of predominantly multifamily homes in the city of New Bedford

5. Element and polyaromatic hydrocarbon concentrations and ratios of selective parent and alkyl polyaromatic hydrocarbons in five constituents of swept street dirt

6. Results of street-sweeper efficiency experiments with a Pelican Series P mechanical sweeper and a Johnston 605 Series vacuum sweeper, by particle size

7. Particle-size distribution of solids swept by the city of New Bedford by a Pelican Series P mechanical sweeper and a Johnston 605 Series vacuum sweeper

8. Element and polyaromatic hydrocarbon concentrations measured in solids swept in the city of New Bedford by a Pelican Series P mechanical sweeper and a vacuum sweeper


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Suggested Citation:

Breault, R.F., Smith, K.P., and Sorenson, J.R., 2005, Residential street-dirt accumulation rates and chemical composition, and removal efficiencies by mechanical- and vacuum-type sweepers, New Bedford, Massachusetts, 2003–04: U.S. Geological Survey Scientific Investigations Report 2005-5184, 27 p.

For more information about USGS activities in Massachusetts, visit the USGS Massachusetts-Rhode Island Water Science Center home page.



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