Limerock Road Dust Control - Hernando County FL
Brian Malmberg, P.E.
LIMEROCK ROAD DUST CONTROL
HERNANDO COUNTY, FL
Presented by Brian Malmberg, P.E.
INTRODUCTION
◉ 375 miles of limerock roads
◉ Low volume local roads are not cost effective to pave with permanent surface at current funding levels
◉ Fugitive dust generated by limerock roads can be an nuisance issue
DUST ABATEMENT
◉ Particles passing No. 200 sieve
◉ Particles form binder in road surface @ Provide agglomeration of particles @ Adhere/bind the surface materials
together
◉ Increase the density of the road material
DUST SUPPRESSANTS
|
Dust Suppression Category |
Typical Suppressants |
Selection for Review |
|
Water |
Water |
Minimal effective duration |
|
Water Absorbing Products |
Magnesium Chloride Calcium Chloride |
Not commonly found in FL Selected for further review |
|
Organic Petroleum Products |
Emulsified Asphalt (sand seal) |
Selected for further review |
|
Organic Nonpetroleum Products |
Animal fats, lignosulfonate, vegetable oil |
Cost prohibitive for large area applications |
|
Electrochemical Products |
Enzymes, ionic products, sulfonated oils |
Cost prohibitive for large area applications |
|
Synthetic Polymer Products |
Polyvinyl acetate, vinyl acrylic |
Cost prohibitive for large area applications |
|
Clay Additives |
Bentonite, Montmorillonite |
Long term constructability Issues, Environmental concerns |
CALCIUM CHLORIDE
◉ Classified as a salt
◉ Deliquescent and Hygroscopic Properties
◉ Applied at 1 to 1.5 lbs/sq. yd.
◉ Scarify, apply, grade, compact
◉ Reduces grading to 3 month cycle
◉ Disadvantages: slippery when wet, vehicle corrosion, degradation of nearby vegetation, potential water pollution
EMULSIFIED ASPHALT
◉ Emulsified asphalt w/ sand coat
◉ Specialized equipment to apply
◉ Forms solid surface and seals roadway
◉ Reduces grading to 4 month cycle
◉ Disadvantages: Must be torn up and completely reapplied at each cycle; potential spills or leaching if not allowed to cure
SCARIFY & REGRADE ROAD
APPLY SUPPRESSANT
FINAL GRADE & COMPACT
COST ANALYSIS
|
Product/ Material |
Limerock Material Cost, $/mile/year |
Suppressant Cost, $/mile/year |
Grading Cycles per Year |
Grading Cost, $/mile/year |
Total Cost, $/mile/year |
|
Crushed Limestone |
$2,275.00 |
$0.00 |
8 |
$239.33 |
$4,189.67 |
|
Calcium Chloride |
$1,137.50 |
$4,375.00 |
4 |
$239.33 |
$6,469.83 |
|
Emulsified Asphalt |
$568.75 |
$4,320.00 |
3 |
$4,320.00 |
$13,528.75 |
|
$682.50 |
$11,314.29 |
2 |
$239.33 |
$23,789.74 |
|
|
$682.50 |
$15,027.69 |
1 |
$239.33 |
$15,949.53 |
Calcium chloride quote – South Eastern Road Treatment Polymer quotes – Soilworks LLC
CONCLUSION
◉ Periodic limerock replacement and grading is most economical
◉ Calcium chloride is most economical dust suppressant but would incur additional costs when compared to current method
◉ Roads under 100 vpd are not cost effective to treat w/ dust suppressant
COMPARISON COSTS
20 Foot Wide Roadway Paving Estimates
ASPHALT PAVEMENT (Cost per mile of Roadway)
|
Description |
Unit Type |
Unit Cost |
Quantity |
Total Cost |
|
Prepare Limerock base for paving |
SY |
$1.90 |
11,733 |
$22,293.33 |
|
Bituminous Prime Coat |
SY |
$0.50 |
11,733 |
$5,866.67 |
|
1-3/4" FC-9.5 Asphalt |
ton |
$80.00 |
1,129 |
$90,346.67 |
|
|
|
|
Sub-Total: |
$118,506.67 |
35% contingency for permitting, additional limerock & swale work Total: $159,984.00
CHIP SEAL SURFACE TREATMENT (Cost per mile of Roadway)
|
Description |
Unit Type |
Unit Cost |
Quantity |
Total Cost |
|
Prepare Limerock base for paving |
SY |
$1.90 |
11,733 |
$22,293.33 |
|
Double Course Chip Seal |
SY |
$3.90 |
11,733 |
$45,760.00 |
|
Fog Seal |
SY |
$0.30 |
11,733 |
$3,520.00 |
|
|
|
|
Sub-Total: |
$71,573.33 |
35% contingency for permitting, additional limerock & swale work Total: $96,624.00
ESTIMATED TOTAL COUNTY PAVING COST
Asphalt Paving Cost $59,994,000
Chip Seal Application Cost $36,234,000
*Approximately 375 miles of limerock roads in Hernando County.
|
COMPARISON COSTS Yearly Comparison Cost |
|
|
PRODUCT/MATERIAL |
TOTAL COST,$/MILE/YEAR |
|
Crushed Limestone |
$4,189.67 |
|
Calcium Chloride |
$6,469.83 |
|
Gorilla-Snot® |
$23,789.74 |
|
Soiltac® |
$15,949.53 |
|
1-3/4” Asphalt Pavement |
$15,998.40 |
|
Double Chip Seal Surface Treatment |
$13,803.43 |
ASSUMPTIONS:
- South Eastern Road Treatment: 3,500 gallons to treat 1 mile, 20' wide, @ $1.25/gallon = $4375
- Soiltac® is 1 gal/65 sf with 1:6 dilution, 275 gallon tote cost $2543.75, 12 month duration
- Gorilla-Snot® is 1 gal/35sf with 1:3 dilution, 275 gallon tote cost $1,031.25, 6 month duration
- Assume 10 year life-span on asphalt pavement
- Assume 7 year life-span on double chip seal pavement
REFERENCES
◉ Bolander, P., & Yamada, A. (1999). Dust palliative selection and application guide. United
◉ States Department of Agriculture, Forest Service. Washington, DC.
◉ Brown, G. M. & Haliburton, T. A. (1984). Road dust control with calcium chloride. Vermont
◉ Local Roads Program Fact Sheet. Colchester, VT: Saint Michael’s College.
◉ CPWA, (2005). Dust control for unpaved roads, a best practice by the national guide to
◉ sustainable municipal infrastructure. Canadian Public Works Association, http://www.infraguide.ca/lib/Db2File.asp?fileid=4555, accessed on April 1, 2011.
◉ FDOT, (2010). Standard specifications for road and bridge construction, Florida Department of Transportation. Tallahassee, FL.
◉ Lohnes, R.A. & Coree, B.J. (2002). Determination and evaluation of alternate methods for
◉ managing and controlling highway-related dust. Final report for Iowa Highway Research Board TR449. Iowa Department of Transportation, Department of Civil and Construction Engineering, Iowa State University, Ames Iowa.
◉ Morgan, R. J., Schaefer, V.R., & Sharma, R. S. (2005). Determination and evaluation of alternate
◉ methods for managing and controlling highway-related dust, Phase II demonstration project. Final report for Iowa Highway Research Board TR506. Iowa Department of Transportation, Department of Civil and Construction Engineering, Iowa State University, Ames Iowa.
◉ Sanders, T. G., Addo, J. Q., Ariniello, A., & Heiden, W. F. (1997). Relative effectiveness of road dust suppressants. Journal of Transportation Engineering, Sept/Oct 1997.
