Transcript Revised Chapter 8, Winter Operations and Salt, Sand and

Strategies to Mitigate the Impacts
of Chloride Based Deicers to the
Environment
Laura Fay
IECA Environmental Connection
February 18, 2015
This work is based on NCHRP Synthesis
449 Strategies to Mitigate the Impacts of
Chloride Roadway Deicers on the Natural
Environment, Revised Chapter 8, Winter
Operations, Salt, Sand and Chemical
Management, and Toxicological Effects of
Chloride-Based Deicers in the Natural
Environment.
Support for these research projects came
from AASHTO Standing Committee on
Highways, Transportation Research Board
(TRB), National Highway Cooperative
Research Program (NCHRP), and the
National Academies.
Acknowledgements…
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Dr. Xianming Shi
Jiang Huang
Michelle Akin
David Veneziano
Eric Strecker
Marie Venner
Outline
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Winter Maintenance Practices
Environments at Risk
Mitigation Techniques
Conclusions
Overview of WM Operations
WM practices - Plowing
The physical removal of snow from the road
using a snowplow.
Sanding
The application of sand, cinders, ash, etc. to
improve friction on the road way.
Anti-icing
The snow and ice
control practice of
preventing the
formation or
development of bonded snow and ice by
timely applications of a chemical freezingpoint depressant.
Deicing
The snow and ice control
practice of breaking the
bond between snow and
ice and the pavement
surface through applications of a chemical
freezing-point depressant.
Pre-wetting
Application of liquid to solid material prior to
placement on the road surface.
Examples
Salt brine sand
Salt brine rock salt
Winter Maintenance Products
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Sand
Treated sand (sand + 10% salt (s,l))
Chlorides – NaCl, MgCl2, CaCl2 (s,l)
Ag-based – beet, corn (l)
Acetates & formates (s,l), glycols (l) &
glycerin (l)
Product Application Rates
• Sand – 100 to 1000 lbs/l-m (32°F and colder)
• Salt/sand – 400 to 1000 lbs/l-m (32 to 0°F)
• NaCl (32 to 15°F)
• solid – 100 to 800 lbs/l-m
• liquid – 10 to 40 gal/l-m
• pre-wet – 8 to 20 gal/l-m
• MgCl2 (32 to -5°F) and CaCl2 (32 to -15°F)
• solid – 100 to 500 lbs/l-m
• liquid – 10 to 40 gal/l-m
• pre-wet – 8 to 20 gal/l-m
Benefits of W.M. Operations
• Fewer accidents, improved mobility, reduced
travel costs, reduced fuel use
• Sustained economic productivity, continued
emergency services, …
W.M. in the U.S.
• > 70% roads, 70% population
affected
• Hwys: 2.3 $bln/yr + 5 $bln/yr
MnDOT Case Study:
• (4,600 crashes)= 29% ↓
• $10.9M in travel time savings
• $48.4M in user fuel savings
• Total $227M saved, b/c of 6.2
• Intangible benefits
Ye, Z., Veneziano, D., Shi, X. Transportation Research Record, 2013, 2329: 17.
Fay, L., Veneziano, D., Ye, Z., Williams, D., Shi. X. Transportation Research
Record 2010, 2169: 174.
Impacts of Salt and Chloride Based Deicers
www.modot.org
Photo courtesy of M. Mills
www.witnerservices.net
www.miissoulanews.bigskypress.com
www.clf.org
www.syracuse.com
www.ci.bellevue.wa.us
Impacts of Acetate Based Deicers
Reduces available oxygen
for organism is the soil and
aquatic environments.
BOD
www.ci.bellevue.wa.us
Impacts of Sand and Abrasives
www.mto.gov.on.ca
www.utah.sierraclub.org
$$$
www.kcsq.com
www.itd.idaho.gov
www.thunderbay.ca
Strategic Planning for Reduced
Salt Usage
• Proactive versus Reactive Measures
Performance Measures
• Winter Operations Performance Measures
– Mobility, reliability, accessibility, safety
– Example: time to bare lane
– Measured as: return to speed, friction, visual
inspection, etc.
www.pbase.com
Performance Measures
• Environmental Performance Measures
– Maintain or improve ecosystem, habitat,
biodiversity, water quality, wetlands, air
quality.
– Example: water quality monitoring
– Data collection: hydrologic, biologic,
atmospheric, etc.
• Resources
– Environmental Guidebook (FHWA), Environmental Review
Toolkit (FHWA), Center for Environmental Excellence
(AASHTO), Eco-Logical, FHWA INVEST Sustainable Highways
Self Evaluation Tool
Salt Management Plans
– A statement of policies and objectives
– Identifies:
• Road use, salt vulnerable areas, storage sites, snow
disposal sites, training, etc.
– Documentation
– Proposed approaches
– Training and Management Review
Iowa DOT Salt Model
• Allocates salt to garages based on
weather conditions and policy usage
requirements.
• Creates a salt budget for each garage
Garage Salt Use Summary
78%
CC
100%
0
Through 4/15/2012
Scale:
200%
Statewide Salt Use vs. Target
Annette Dunn, Iowa DOT
D1
551602
551604
551605
551607
551608
551609
551611
551612
551613
551614
551802
551803
551804
551806
551807
551808
551809
Garage
Ames
Marshalltown
Tama
Grundy Center
Iowa Falls
Williams
Fort Dodge
Gowrie
Jefferson
Boone
Malcom
Grinnell
Newton
Altoona
Des Moines North
Grimes
Carlisle
< 90%
Allocation
(Tons)
Salt Used
(Tons)
Salt Target
(Tons)
3,057
1,871
1,315
1,714
1,796
2,179
1,573
840
1,005
1,263
1,185
1,106
2,370
1,261
2,778
3,750
1,603
1,163.4
829.6
717.8
459.8
512.4
726.3
558.3
156.0
459.3
688.2
628.4
488.5
921.3
542.6
972.4
1,264.8
542.7
1,710.4
1,081.7
642.5
689.1
820.6
1,133.7
771.6
449.4
488.1
573.5
674.4
568.9
1,045.9
410.9
1,012.0
1,636.0
429.6
90% - 100%
% Target
Used
68.0%
76.7%
111.7%
66.7%
62.5%
64.1%
72.4%
34.7%
94.1%
120.0%
93.2%
85.9%
88.1%
132.0%
96.1%
77.3%
126.3%
Payperiod 13 & 14
Over 100%
% Allocation
Used
38.1%
44.3%
54.6%
26.8%
28.5%
33.3%
35.5%
18.6%
45.7%
54.5%
53.0%
44.2%
38.9%
43.0%
35.0%
33.7%
33.9%
Training for Salt Management and
Winter Maintenance Operations
• Assess the needs of your staff
• Consider who is being trained and how to
best convey that information
• Design training based on learning goals
• Training methods:
– Classroom, field, post-storm debriefing,
simulator, etc.
Training Continued…
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Have experienced staff conduct the training
Evaluate your training program
Assess how much information was learned
Common training methods:
– Annual operator training, Snow University,
Snow & Ice Rodeo, Computer Based Training
(CBT)
www.capitalbay.com
www.triblocal.com
Monitoring and Keeping Records
• Determine your baseline
• Use collected data to find trends
• Consider tracking:
– Total length of road
– Winter severity rating
– Number of events
– Material used
– Calibration dates
– Treatment effectiveness
Calibration
• Is a must
• Why: to realize savings gained from
investment in new technology
• Train how to calibrate & keep records
• When to calibrate:
– When first acquired, points throughout a
season, whenever a new material is used,
after repairs, if there appears to be
discrepancy in material usage
Material Storage
• All products should be stored in a manner
to minimize any loss of product.
www.syracuse.com
Anti-icing
“the snow and ice control practice of prevent
the formation or development of bonded snow
and ice by timely applications of a chemical
freezing-point depressant”
• LOS, product, abrasives & plowing
• 10 – 40 gal/l-m
• Cost savings, mobility & safety
• Side benefit of reducing impacts to the
environment, infrastructure, and
vehicles.
• Limitations:
– Cold temps, rain/sleet, blowing snow, air temp above
freezing and rising, high humidity
Pre-Wetting Solid Material
• Adding liquid to products or
abrasives at stockpile or at the
spreader
• Benefits
– Eases product management and distribution
– Accelerates breakup of snow/ice and enhances
melting
– Minimizes bounce and scatter, improves performance
– Increases longevity on road = less frequent
applications
Reducing Sand Usage and
Managing Traction Materials
• Pre-wetting
– Liquid product
– Hot water
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Heating sand
Using other materials
Reduce bounce/scatter
Apply in appropriate locations
– Low speed roads, hills, curves, intersections
Sand and Abrasives Continued..
• The detrimental environmental impacts of
abrasives generally outweigh those of
chemical products.
• Abrasives require more material and
provide a lower LOS
www.mto.gov.on.ca
www.syracuse.com
www.witnerservices.net
RWIS
Real-time road condition information
• Used to time treatments and
determine which treatments to
use
• Benefits:
– LOS
– Cost savings
– Aid in maintenance response
– Efficiency
• Cost-benefit ratio : 1.4 to 11
Pavement Sensors &
Thermal Mapping
Maine DOT
• Monitoring, planning, treatment
strategies, forecasting
• Invasive and non-invasive
www.enterpriseflasher.com
www.cbc.ca
www.bangordailynew.com
www.vaisala.com
Friction Measurements
www.vaisala.com
• Indicator of road condition
• Monitoring, planning,
treatment strategy, prevent
over application
• Friction to assess
Performance Measures
(CDOT)
– Non-contract friction measurements
– Noticed difference in products
performance
– Provide good short/long term
assessment of product performance
www.mastrad.com
www.highfrictionroads.com
www.dot.state.oh.us
Residual Chemical Measurement
Salinity sensors have been used to make educated decisions
about reapplication (Ye et al., 2012).
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Monitor road surface product concentration
On-vehicle, embedded, or non-contact
Accurate/recalibrated application rates
Link measurements with automatic spreader
controls
• Benefits:
– Prevents over application, saves material and $$$
Road Weather Management
Decision Support
Tools that integrate road weather forecasts, coded maintenance
rules of practice, resource data to provide recommended
treatment strategies (FHWA 2011)
• Software application, weather forecast and
predictions, road weather reports, training tools.
• Benefits:
– Cost and material savings, benefit-cost: 1.33 to 8.67, less
use of vehicles
• Lessons learned:
– Time needed to refine forecast & get management on board,
continued training and exposure
MDSS
Weather Forecasts and Information
Services
• Research has shown that winter maintenance
costs decrease as the use of weather
information increases (Ye et al., 2009).
• Accurate and timely forecasts have been shown
to save 11–25% (labor) and 4-10% (material),
but using a bad forecast can cost you (Shi et
al., 2007)
• Improved spatial resolution will provide greater
expected benefits to service levels (Fu et al.,
2009).
Drift Control and Snow Fences
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Reduce blowing and drifting snow
Low cost snow storage
Increased safety
Reduce need for snow & ice control product
25 year lifespan at $1.40 per ft2
Wildlife habitat, control
erosion, improve water quality,
reduce spring-time flooding,
sequester carbon.
≥8 ft
Proactive BMPs
• EPA pollution prevention for operation and
maintenance of highways:
– Cover salt storage piles and deicing materials
– Store all materials outside of the 100 yr flood
plain
– Regulate application rates
– Use specialized application equipment
– Avoid dumping snow into surface waters
Reactive Strategies
So there are deicing chemicals and sand out
on the road and in the environment, what do
we do now
- Clean it up
- Capture it
- Dispose of it
Storage and Release
• Detention, Retention, &
Evaporation Ponds
• Wetlands and Marshes
The primary
mechanism of
storage and release
BMPs is mixing of
runoff to reduce
peak chloride
concentrations .
Infiltration
Infiltration trenches and
basins treat runoff and
reduce surface runoff
water by allowing water
to infiltrate into the
Avoid if location has a
surrounding/underlying shallow water table.
soils and groundwater
Chlorides can be stored
systems.
and later released in
greater concentration.
Alternatives methods to remove
chlorides?
• Capturing chlorides in filter media
(dolomite, calcium, or recycled concrete)
– > Sorption of chloride to filter media.
– More research is needed to determine the
effectiveness.
(Villagran-Zaccardi et al., 2008)
Conclusions
Deliver the right type & amount of materials in
the right location at the right time
effectiveness & efficiency of winter operations
material usage, $$$, environmental footprint
Balancing LOS vs. sustainability:
best practice in technology &
management domains
Questions?
www.cylelicio.us
Thank you for your time.
Laura Fay
Winter Maintenance & Effects Program Manager
Research Scientist II
Western Transportation Institute
Montana State University
[email protected]
406-600-5777