Limerock Road Dust Control - Hernando County FL

Brian Malmberg, P.E.
2011-08-17
Hernando County

LIMEROCK ROAD DUST CONTROL 

HERNANDO COUNTY, FL

Presented by Brian Malmberg, P.E.

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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

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APPLY SUPPRESSANT

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FINAL GRADE & COMPACT

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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

Gorilla-Snot®

$682.50

$11,314.29

2

$239.33

$23,789.74

Soiltac®

$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.

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