Cost-efficiency of the dust binding and street cleaning measures

Transcription

1 Cost-efficiency of the dust binding and street cleaning measures Results from REDUST Action 3 Jarkko Niemi Helsinki Region Environmental Services Authority (HSY) REDUST final seminar 30 September 2014 Helsinki 1

2 Cost-efficiency of dust binding and street cleaning Cost-efficiency = Cost of measures ( ) / Dust emission reductions (kg) To estimate cost-efficiency, the following street-specific information was calculated for REDUST city routes PM 10 street dust emissions in spring Emission reductions and costs caused by dust binding and street cleaning 2

3 City routes for emission and cost calculations PM 10 dust emissions and costs of reductions were calculated for the REDUST city routes in Espoo Helsinki downtown (Centre, East, West) Vantaa The number of different street sections 28 and their total length about 20 km 5 km Espoo Espoo Helsinki Vantaa Helsinki West Centre East 3

4 Calculation method - street dust emissions in spring 1. Dust load increases in street environment during winter due to use of studded tyres and traction sanding. Dust resuspension mainly suppressed since icy, snowy or wet streets. 2. Dust emission peak occurs in early-spring as streets dry out 3. Dust load and emission decrease during spring due to self-cleaning by water flows (rain and melting snow) and air flows (traffic and wind) dust binding and street cleaning 4

5 Street dust emissions only from dry streets Dust emission estimate = Potential dust emission x Dry street proportion (% of daily hours) Dust emissions only from dry streets No dust emissions when wet, icy or snowy streets Road surface dryness data (conductivity sensors combined with remote surface state sensors) from 4 major roads in the Helsinki region was used to estimate dust resuspension Source: Finnish Transport Agency,

6 Change relative to reference Dust emission reduction by street scrubber Modern street scrubber (PIMU cleaning) PM 10 dust emission reduction during first day after cleaning even 40% for very dusty streets and only 10% for cleaner streets Impact of cleaning was estimated to end gradually during one week Long-term impacts of cleaning were neglected Impact of street scrubber on PM 10 streetside PM 10 dust emission reduction by street scrubber in the REDUST calculations: Street dust level before * Treatment day cleaning (Sniffer, μg/m 3 ) Day 1* Day 2 Day 3 Day 4 Day 5 Day 6 Day 7 Day 8 over % -30 % -20 % -16 % -12 % -8 % -4 % 0 % % -26 % -18 % -14 % -11 % -7 % -4 % 0 % % -23 % -15 % -12 % -9 % -6 % -3 % 0 % % -19 % -13 % -10 % -8 % -5 % -3 % 0 % % -15 % -10 % -8 % -6 % -4 % -2 % 0 % % -11 % -8 % -6 % -5 % -3 % -2 % 0 % below % -8 % -5 % -4 % -3 % -2 % -1 % 0 % Street scrubber 6

7 Change relative to reference Dust emission reduction by vacuum sweeper Traditional vacuum sweeper alone is not efficient in reducing PM 10 dust but subsequent water flushing improves efficiency PM 10 dust emission reduction 10% during the first day after cleaning for every street dustiness levels Impact of cleaning was estimated to end gradually during one week Might be underestimation more tests needed if future Long-term impacts of cleaning were neglected Impact of vacuum sweeper on PM 10 streetside Vacuum sweeper + water flushing PM 10 dust emission reduction by vacuum sweeper and water flushing in the REDUST calculations: Day 1* Day 2 Day 3 Day 4 Day 5 Day 6 Day 7 Day 8 Same for all dust levels -10 % -8 % -5 % -4 % -3 % -2 % -1 % 0 % * Treatment day 7

8 Dust emission reduction by dust binding In the Helsinki region, the dust binding solution is mainly dispersed with specially designed spreader systems to kerbsides and sometimes also between the lanes (but not usually to the center areas of lanes) CaCl 2 solution usually 5 10 weight-% (even 15% for some streets, if no risk for slippery) PM 10 dust emission reduction by targeted dust binding in the REDUST calculations: Dust binding area Day 1* Day 2 Day 3 Kerbside && center between lanes 40 % 20 % 0 % * Treatment day 8

9 Street-specific adjustments of calculations The calculation model was adjusted separately for every street section (total # 28): Dust emission peak level based on Sniffer measurements Reduction by dust bindings Reduction by street cleanings The best fit between calculated and measured dust emissions after mid-march --> results were only calculated for the most reliable 2 months period (blue rectangle) In February and at the beginning of March, the local snow and ice melting waters caused discrepancies Hämeentie street Sniffer 9

10 Indicative PM 10 emission (kg/km) Emissions = number of vehicles x emission factors Indicative daily dust emissions (kg/km) were calculated for every street vehicles per weekday Heavy duty vehicles 3 22% Emission factors (EF) based on Sniffer upwind-downwind tests in the REDUST project Daily EF levels for light duty vehicles were mg/vehicle-km, depending on dustiness and dryness of streets Indicative PM 10 dust emissions (kg/km) caused by traffic in Hämeentie street Date 10

11 PM 10 dust emission (kg/km/day) Results - dust emissions in springs Large variation in PM 10 dust emissions for different streets during the two-month spring periods Indicative dust emissions typically 10 kg/km/day, ranging between 1 and 40 kg/km/day The highest emissions in busy and dusty streets The lowest emissions in low-traffic and clean streets Differences between years the highest emission in spring 2013 due to cold and dry weathers Dust from construction works Centre East West Vantaa Espoo 11

12 Dust emission results on map - Helsinki In Helsinki downtown, high dust emissions and PM 10 concentrations often occur in busy street canyons, where buildings prevent dilution of air pollutants by winds. Therefore, the most efficient dust mitigation measures are needed in Helsinki Hämeentie Mannerheimintie 12

13 Daily PM 10 emission (kg/km) Emission reductions by dust binding and cleaning Clear differences in dust binding and street cleaning in spring 2014: Dust binding (#) Street cleaning (#) Helsinki Centre street scrubber Helsinki West vacuum sweeper Helsinki East 8 1 vacuum sweeper Vantaa mainly street scrubber but also vacuum sweeper Espoo street scrubber or vacuum sweeper Helsinki Centre Mannerheimintie1 Helsinki West Mannerheimintie2 Vantaa Tikkurila1 Espoo Leppävaarankatu 13

14 Reduction by dust binding (%) Emission reductions by dust binding in The emission reduction by dust binding varied from 0 to 23% in the city routes The highest total reduction 23% in Helsinki Centre in 2012 due to numerous (# 26) dust bindings Dust binding was no more used in Espoo in years Centre East West Vantaa Espoo 14

15 Reduction by cleaning (%) Emission reductions by cleaning in The emission reduction by street cleaning varied from 1 to 4% in the city routes The highest reduction 4% in Vantaa in 2014 due to several cleanings with street scrubber The efficiency of cleaning underestimated, since not enough knowledge on total impacts (longterm impact, various combined cleaning methods in use) Centre East West Vantaa Espoo 15

16 Cost estimates for dust binding and street cleaning Costs were estimated for three typical procedures Dust binding with CaCl 2 solution (5 10%) on kerbside 40 /km Traditional street cleaning with vacuum sweeper often complemented with water flushing 400 /km Street cleaning with modern street scrubber (PIMU-cleaning) sometimes complemented with water flushing 600 /km These rough price estimates include the costs of machinery, materials (water and CaCl 2 ) and wage The price estimates do not include Removal of coarse gravel from streets and sidewalks with mechanical sweepers Moving of improperly parked cars before cleaning Cleaning of special areas, such as bus stops or bridges Administration costs The same unit price estimates were used for every street in this work, since better input data was not available Targeted dust binding Street scrubber Vacuum sweeper + water flushing 16

17 Cost-efficiency of dust binding and cleaning The unit cost per reduced dust emissions varied much in different areas The REDUST city routes in spring 2014 as an example; The lowest cost (8 17 /kg) in the Helsinki routes. The frequent use of dust binding in busy streets decreased costs per reduced dust. The highest cost (130 /kg) in Espoo. Dust binding was not used and late cleaning times. Costs of measures / Emission reductions > Cost per reduced dust 17

18 PM 10 dust emission reduction (kg/km) Dust binding of different streets in High variation in input costs ( /km), dust emission reductions (kg/km) and costefficiency ( /kg) Typical indicative cost per reduced PM 10 dust emission was only 5 /kg Highest cost-efficiency (2-4 /kg) when high traffic count and dustiness level Lower cost-efficiency (10-20 /kg) when very low traffic rate too late timing in spring (already clean) rains after dust binding Costs ( /km) 18

19 PM 10 dust emission reduction (kg/km) Cleaning of different streets in High variation in input costs ( /km), dust emission reductions (kg/km) and cost-efficiency ( /kg) Typical indicative cost per reduced PM 10 dust emission was quite high 120 /kg Highest cost-efficiency (~20 /kg) when street scrubber was used on streets with high dust load Lower cost-efficiency (~300 /kg) when too late cleaning times in spring (already clean) very low traffic rate rainy days after cleaning (masks the impacts of cleaning) Costs ( /km) 19

20 PM 10 emission (kg/km) Maximum spring dust reduction in Helsinki Centre Dust bindings # in February-May: 1. The first dust bindings in early-spring targeted to kerbs due to night frosts 2. Whole street dust bindings during the most severe dust episode days 3. Targeted spreading in late-spring Multistep combination cleaning with street scrubber at the beginning of April: 1. Parking not allowed during cleaning day 2. Mechanical sweeper collects coarse sanding materials 3. Street scrubber reduces PM 10 dust containing material 4. Water jet truck flushes PM 10 dust to street drainage sinks Additional cleanings before and/or after the combination cleaning Street scrubber (or vacuum sweeper) used 1-4 times during spring Helsinki Centre HSY / Kai Widell 20

21 Toolbox for street dust mitigation measures Several dust mitigation measures are needed to achieve clean urban air in spring wet-sieved sanding materials (e.g. 1-6 mm), non-studded and light-studded winter tyres, low driving speeds 21

22 Conclusions Both dust binding and efficient street cleaning are needed most intensive and early measures on streets with high traffic rate Intensive dust bindings may reduce even 25% of PM 10 dust emissions in spring cost-efficient way to decrease high dust concentration peaks does not remove dust, but gives time for cleaning to do it optimization based on air quality monitoring and weather forecasts potassium formate better than chlorides in groundwater areas (Finnish Environment Institute) Street scrubber and combination cleaning reduce PM 10 dust vacuum sweeper alone is not efficient efficient combination; mechanical sweeper + street scrubber (or vacuum sweeper) + water jet most efficient cleaning when high dust load early timing and repeat later total efficiency underestimated, long-term impacts? R&D still needed to improve cleaning efficiency 22

23 Thank you! Materials available from the REDUST webpages HSY / Kai Widell HSY / Kai Widell jarkko.niemi@hsy.fi 23