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UNPAVED ROAD DUST MANAGEMENT
A Successful Practitioner's Handbook

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CHAPTER 1 - INTRODUCTION

The compelling incentive for this handbook on Unpaved Road Dust Management, and the earlier 2010 Survey and National Scan of Best Practices for Chemical Treatments on Unpaved Roads, was the recognition that road dust, and the chemicals used in its control, pose difficult engineering, economic, regulatory, health, safety, and environmental challenges. These challenges need to be better understood and overcome so that chemical treatments are used appropriately across the nation. This handbook is aimed at practitioners who deal with such challenges on the ground and whose individual challenges may be unique to their region.

Even though this document touches on road management issues at the program level, it is not a blueprint for project level unpaved road construction and maintenance. It is not a prescription for determining the correct type and quantity of dust abatement chemical to apply to roads. It is not a checklist for measuring how one county's program
ranks against others across the nation, and it is not a research reference documenting the effectiveness of chemical treatments used in experiments and field trials. While the authors find value in these goals and believe that some warrant further study, they are not within the scope of this work because:

  • Different types of roads require different levels of service (Figures 7 and 8).
  • Each locale faces different challenges in terms of subgrade soil types, climate, topography, availability of wearing course aggregates and chemical additives, population and traffic demands, etc. - all of which affect the longevity of a road and the durability of its treatments.
  • Different agencies have different equipment fleets.
  • Different funding mechanisms require different approaches to road management and, in the end, dictate what is possible for road improvement efforts.

Figure 7. Photo. Low volume access road.

Figure 8. Photo. High volume haul road.

For example, most chemical treatments rely on mechanical and/or chemical reactions with the soil to be effective. Roads constructed with geologically young glacially deposited material are going to behave very differently from roads constructed with highly weathered basalt materials with high clay contents. Consequently, different road management approaches and different chemical treatment programs will need to be followed.

A wide variety of generic and vendor-specific chemical treatments are available to road practitioners. Although it would be nice to identify the single best cost-effective chemical treatment on the market, guaranteed to work the first time, every time, on the more than one million miles of unpaved roads constructed in the 3,141 counties in America, there are just too many variables for that to be a realistic goal. With balanced judgment of their effectiveness, availability, cost, and safety, practitioners will find that more than one product will probably provide efficient and effective road dust management solutions for a given set of conditions.

What's possible in Bonner County, Idaho, where property valuation reaches $6 billion and the road network totals 700 miles with 425 miles of unpaved roads, is probably not achievable in Woodbury County, Iowa, with a road network twice that size and little more than a tenth the property valuation.

WHY CHEMICAL DUST CONTROL?

Depending on the situation, treating an unpaved road with an appropriate additive generally limits the fines loss. Fines are the "glue" that holds the larger aggregates of an unpaved road together to form the surface layer. Keeping fines in the road leads to:

  • Reduced dust levels;
  • Improved safety and driver experience;
  • Improved air and water quality by reducing particulate matter and sediment runoff;
  • Improved quality of life of nearby residents;
  • Extended intervals between gravel replacement needs;
  • Reduced maintenance costs through extended intervals between grader blading needs; and
  • Reduced public complaints.

PURPOSE OF THE HANDBOOK

Cover of handbook

This handbook is offered as a guide that supplements existing manuals and guidelines to creating sustainable, long-term management programs for maintaining unpaved roads in counties, and on federal lands, forests, mines, farms, and other jurisdictions. Sustainable is meant as meeting objectives and being affordable, cost-effective, and with minimal environmental impact, both in terms of the chemical treatment applied and the aggregate retained through conservation of fines and road shape. It also means providing a level of service to road users that affords them safe and comfortable transportation and a nuisance-free environment, not simply to reduce complaints but also to assure their continued willingness to fund effective road management efforts through their tax dollars.

IT'S THE PROCESS, NOT JUST THE PRODUCT

One of the aims of this handbook is to elevate road managers' thinking to a broader scope about the process of unpaved road management using chemical treatments as a road management tool, not just focusing on the use of a specific chemical treatment or product. Understandably, once a certain treatment is used, it can be difficult to redirect from the inertia. But focusing on one product can be risky. What happens when market demand drives up prices, a supplier goes out of business, a local supply is used up, or new research flags a favored product as potentially unsafe or toxic? The point is even with experience and a treatment that seems to work, it is always a good idea to stay abreast of other available additives, technologies, and techniques.

"I conduct product testing with vendors. I tell them I'll pay if it works as they say it will. If it doesn't, at least I learned something." - Scan tour host

Experimenting with different products can be worthwhile, but only if new information is gathered, a basic scientific procedure is followed in the evaluation (that is, comparing a new approach with the existing approach and/or an untreated control), and the process is documented. In a similar way, hard-won knowledge gained from experience is often lost when staff members move on or retire. Careful thought should be put into succession training for employees to maintain continuity and ensure that valuable wisdom stays in the shop. While it may be necessary due to limited budgets for one person to do it all, a better program consists of a team of individuals, who document what they do, how they do it, and what they learn (both good and bad experiences). All of this thinking about process will help justify the costs and savings.

It's not enough to hear "it works," "it's environmentally friendly" or "it's cheap." When the vendor or contractor is required to meet product and/or aggregate specifications, there should be follow up to see that these have been met. Furthermore, product specifications and Material Safety Data Sheets (MSDS) should be verified with an independent accredited laboratory. Colleagues in neighboring jurisdictions, peer-reviewed research and relevant associations can be great sources of information. At the base of it all, succeeding in the process of unpaved road management using chemical treatments requires a solid understanding of quality road construction because a product is only as good as the road on which it is applied.

Key Terminology

Different words mean different things to different people in different parts of the country. In this handbook the following general terminology is used:

Product - chemical treatment, additive, palliative or stabilizer applied for the purpose of dust control (that is, fines retention) and/or stabilization (that is, improved all weather passability).

Material - aggregate, gravel or soil to which the product is applied.

Unpaved - unsealed, unsurfaced or gravel roads.

The terms Dust Control and Road Stabilization - Keeping the fines on the road (dust control) helps maintain the cementitious matrix needed to keep the road aggregate in place (road stabilization).

SUGGESTED READING

The following documents provide guidance on all aspects of unpaved road design, construction, and maintenance. Most of the documents include discussion of dust control and unpaved road stabilization. All of the documents can be downloaded from the Internet. Full references are provided at the end of the document.

  1. Dust Palliative Selection and Application Guide. (Bolander and Yamada, 1999).
  2. Dust Control Guidance and Technology Selection Key. (Gebhart, Denight, and Grau, 1999).
  3. Gravel Road Management: Implementation Guide. (Huntington and Ksaibati, 2010).
  4. Chemical Treatments on Unsealed Roads: Establishing a Chemical Treatment Program. (Jones, 2008).
  5. Chemical Treatments on Unsealed Roads: Additive Selection Guide. (Jones, 2008).
  6. Chemical Treatments on Unsealed Roads: Unsealed Road Evaluation Guide. (Jones, 2008).
  7. Chemical Treatments on Unsealed Roads: Protocols for Researching the Performance of Additives. (Jones, 2008).
  8. Chemical Treatments on Unsealed Roads: Fit-for-Purpose Certification of Additives. (Jones, 2008).
  9. Dust Control Field Handbook: Standard Practices for Mitigating Dust on Helipads, Lines of Communication, Airfields, and Base Camps. (Rushing and Tingle, 2006).
  10. Gravel Roads Maintenance and Design Manual. (Skorseth and Selim, 2000).
  11. Guidelines for Cost Effective Use and Application of Dust Palliatives. (Smith, Makowichuk and Carter, 1987).
  12. Unsealed Roads: Design Construction and Maintenance. (Paige-Green, et al, 2009).
  13. Guidelines for Geometric Design of Very Low-Volume Local Roads (ADT ≤ 400), 1st Edition.

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