1. Presented by Brian Malmberg, P.E.

2. 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

3. 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

4. DUST SUPPRESSANTS Dust Suppression Category Typical SuppressantsSelection for Review Water Minimal effective duration Water Absorbing Products Magnesium Chloride Calcium Chloride Not commonly found in FL Selected for further review Organic Petroleum ProductsEmulsified 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 ProductsPolyvinyl acetate, vinyl acrylic Cost prohibitive for large area applications Clay AdditivesBentonite, MontmorilloniteLong term constructability Issues, Environmental concerns

5. 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 $13,528.75 Gorilla-Snot$682.50 $11,314.29 2$239.33$23,789.74 Soiltac$682.50$15,027.691$239.33$15,949.53 Calcium chloride quote – South Eastern Road Treatment Polymer quotes – Soilworks LLC

6. 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

7. COMPARISON COSTS Yearly Comparison Cost PRODUCT/MATERIALTOTAL COST, $/MILE/YEAR Crushed Limestone$4,189.67 Calcium Chloride$6,469.83 Gorilla-Snot$23,789.74 Soiltrac$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