Module 4a: The Role of Street Cleaning in Stormwater Management

Transcription

1 Module 4a: The Role of Street Cleaning in Stormwater Management Major Sediment Source Along Highways Robert Pitt Department of Civil and Environmental Engineering University of Alabama, Tuscaloosa, AL Roger Bannerman Wisconsin i Dept. of Natural Resources, Madison, WI Roger Sutherland Pacific Water Resources, Beaverton, OR Wisconsin Dept. of Natural Resources Heavy Street Dirt Loadings after Snowmelt Roger Bannerman photo 1

2 Some Early Street Cleaning Research Projects Pitt, R., Demonstration of Nonpoint Pollution Abatement t Through h Improved Street t Cleaning Practices Bannerman, R. et. al, Evaluation of Urban Nonpoint Source Pollution Management in Milwaukee County, WI Terstriep, M.L., et. al, Evaluation of the Effectiveness of Municipal Street Sweeping in the Control of Urban Storm Runoff Pollution Street and catchbasin cleaning, and inlet controls most effective for smaller rains or heavily paved areas. 2

3 Redistribution of Street Dirt During Street Cleaning Pitt 1985 Total Solids Removal by Street Cleaning Particle Size Distribution of Street Dirt 3

4 Street Dirt Chemical Quality (mg/kg) (Milwaukee, WI; San Jose, CA; Bellevue, WA; Toronto, Canada; Reno, NV; Champaign, IL) Phosphorus (P) Total Kjeldahl Nitrogen Chemical Oxygen 65, ,000 Demand Copper (Cu) Lead (Pb) Zinc (Zn) Cadmium (Cd) <3 5 Chromium (Cr) Pitt, Bannerman, and others Role of Street Cleaning in Leaf and Nutrient Control in Fall? Size Distribution of Total P in Street Dirt Percent < >250 Leaves Microns 4

5 Sawtooth Pattern Associated with Deposition and Removal of Particulates Washoff of Street Dirt, Bellevue, WA Pitt 1985 Total Solids Removal by Street Cleaning 5

6 Washoff Plots for Heavy Rain Intensities, Dirty Streets, and Rough Pavement Textures Ratio of Available SS to Total SS Street Dirt Loadings Pitt 1987 Pitt 1987 Particle Size Distributions during Washoff Tests (high rain intensity, clean and smooth streets) Pitt 1987 Pitt

7 Measured Particle Sizes, Including Bed Load Component, at Monroe St. Detention Pond, Madison, WI Particle Settling Rates; Stoke s and Newton s Laws Total Particulate Loading, Keyes Good Asphalt Test Area 7

8 Total Solids Accumulation Since Last Cleaning Deposition and Accumulation of Street Dirt Pitt 1979 Example Deposition and Accumulation Rates (many studies) Particle Resuspension Rates Caused by Vehicle Passage for an Asphalt Road Initial load Depos. Rate Days to (g/m) (g/m-d) max. load Reno, NV, smooth and good condition San Jose, CA, good condition 35 4 >50 Castro Valley, CA, mod. condition Ottawa, Ontario, mod. condition, indus >10 Toronto, Ontario, mod. condition, resid >10 Bellevue, WA, smooth, heavy traffic San Jose, CA, oil and screens overlay >50 Ottawa, Ontario, rough >10 8

9 Measured Fugitive Dust Losses from Streets, San Jose, CA Effects of Parked Cars on Street Cleaning Keyes, good asphalt Keyes, oil and screens asphalt Tropicana, good asphalt 6 lb/curbmi/day 4 lb/curbmi/day 6 lb/curbmi/day 0.33 grams/vehiclemi 18 grams/vehicle-mi 2.5 grams/vehiclemi 9

10 High-Efficiency Street Cleaner Tests, Milwaukee, WI -mile) After load (lb/curb y = x R 2 = Before load (lb/curb-mile) WI DNR and USGS ) Test site s.sed (mg/l) Comparison of Suspended Sediment at Test and Control Sites for Swept and Unswept Periods Test Site Control Site No Sweep y = x R 2 = Swept y = x R 2 = Control site s.sed (mg/l) Summary of Current Street Cleaning Tests Linear Regression Robust LTS Regression SWEEPER Slope Efficiency Slope Efficiency Pelican % % Plastic Bristles % % Crosswind % % Whirlwind % % 2,000 1,800 1,600 1,400 "No Change" Pelican Sweeper Efficiencies These are street dirt loadings, not outfall TSS concentrations. Post Sweeping (lbs./ /curb mi) 1,200 1, Minimum initial load for which sweeping has a positive effect Initial load BASIN (lbs/curb-mile) Piping Rock 700 Kroncke ,000 1,200 1,400 1,600 1,800 2,000 Pre Sweeping (lbs/curb mi) 10

11 Conclusions Sediment in urban streams is a serious problem. Rains only remove a small fraction of the total particulate load from paved surfaces, mostly the smallest particles. Street cleaning only removes a small fraction of the street dirt loading, mostly the larger particles. The accumulation rate is much less than expected due to residual load. Particle size distributions at outfalls are mostly made up of small particles (larger particles that wash off accumulate in sewerage) Particle size distributions of source area sheetflows have large particles, but many of these aren t effectively transported to outfalls. Most models are out of balance on source area contributions. Conclusions (cont.) Water Quality Benefits of Street Cleaning is Limited Best in Spring Role in Aesthetics and Safety Performance Effected by Street Load, Particle Size, Street Texture, e, Method of Operation, & Parking More Effective for Particles > 250 micron (which are few in runoff waters) Three Components to Modeling Street Cleaning Street Cleaning Dates Street Cleaner Productivity Parking Conditions Street Cleaning Data Street Cleaning Dates and Frequency 11

12 Street Cleaning Data Street Cleaner Productivity Parking Conditions Street Cleaning Sensitivity Street Cleaning Performance Plots If BeforeEventLoad < B / (1 - M) Then AfterEventLoad = BeforeEventLoad Else AfterEventLoad = M * BeforeEventLoad + B End If Washoff Details.csv Street Dirt Removal.csv Additional Output Washoff or Street Cleaning.csv BEGIN STREET CLEANING/WASHOFF LOOP FOR STREET 1 Event Type Rain# St# Date JulDate AccumDur CurrentLoad BeforEvntLoad AftEvntLoad PartSolYield Washoff /12/ , , , Washoff /14/ , , , Washoff /20/ , , , Washoff /21/ , , , Washoff /22/ , , , Washoff /25/ , Street 1, Dirt Washoff 1, and 0.81 Washoff /30/ , , , Washoff /31/ , Removal 1, due 1, to Street Washoff /01/ , , , Cleaning Washoff /03/ , , , Washoff /08/ , , , Washoff /09/ , , , Washoff /14/ , , Street Cleaning Street Cleaning Washoff /24/ Washoff /28/ Washoff /30/ Washoff /01/ Washoff /02/ Street Cleaning Street Cleaning Washoff /17/ Washoff /21/ Street Cleaning Washoff /22/ Washoff /24/ Street Dirt Changes Over Time Level (lbs/curb-mi) Street Dirt Example Accumulation, Washoff and Street Cleaning Curve Maximum Load on Street t 1, , Time (days) Street Cleaning Dates 12