Soilworks products are the industry’s top standard due to our insistence on creating high performance soil stabilization and dust control products that stand up to rigorous testing – both in the lab and in the field. Our commitment to quality and performance has led to our involvement and testing in hundreds of real-world situations. The following library of reports, presentations, specifications, approvals and other similar documents provide you, our customer, the transparency and dependable assurance that is expected from Soilworks.
NAVfAC
NAVAL FACILITIES ENGINEERING COMMAND
Washington, DC 20374-5065
NFESC
User Data Package
UDP-2006-ENV
USER DATA PACKAGE FOR POLYMER AND LIGNOSULFONATE TYPE
DUST SUPPRESSANTS
November 1999
19991215 069
Approved for public release; distribution is unlimited.
() Printed on recycled paper
|
NSN 7540-01-280-5500 Standard Form 298 (Rev. 2-89)
Prescribed by ANSI Std. 239-18 298-102
EXECUTIVE SUMMARY
Wheeled and tracked vehicle operation on dry, unsurfaced landscapes creates tremendous amounts of fugitive dust as soil particles are dislodged and carried into the atmosphere through wind action. During wet weather, these dislodged soil particles are subject to water erosion, which has the potential to carry them into surface waters and thereby reduce water quality and create sedimentation problems for streams and wetlands.
Historically, numerous products have been developed and used to control dust on unsurfaced landing zones, roads, and trails. Some products, such as used motor oils, industrial manufacturing wastes, and other petroleum based derivatives, have damaging environmental effects and their use is now prohibited. However, recent developments in dust-control technology have provided a number of environmentally safe materials similar in cost, efficacy, durability, and maintenance requirements, especially on unimproved roadways where rougher terrain may make traditional road maintenance more difficult and costly.
The dust control measure of most common resort is that of applying a material to the dust source that prevents the dust emissions. Dust control products currently on the market are categorized as petroleum oils/resins, lignosulfonates, asphaltic emulsions, or polymer emulsions. The information in this User Data Package (UDP) is intended to provide guidance to Public Work Centers, environmental, and safety managers in the use of polymer and lignosulfonate type dust suppressants. This UDP discusses the suitability of these dust suppressants, selection criteria, site preparation, product application, product evaluation, and maintenance of treated areas.
11
ACKNOWLEDGEMENT
This work was funded by the Pollution Abatement Ashore program, managed by Naval Facilities Engineering Command and sponsored by the Environmental Protection, Safety and Occupational Health Division (N45) of the Chief of Naval Operations. A majority of test and evaluation data was obtained from Natural Resources Environmental Affairs located at Marine Corps Air Ground Combat Center in Twentynine Palms, California.
Page
1.0 Introduction 1
2.0 User Data Package For Polymer And Lignosulfonate
Type Dust Suppressants 1
3.0 Regulatory Requirements and Reporting Issues 2
4.0 Description of Polymer and Lignosulfonate Suppressants 3
4.1 Polymer Type Dust Suppressants 3
4.2 Lignosulfonate Type Dust Suppressants 3
5.0 Dust Suppressant Suitability For Various Field Applications 4
6.0 Considerations For Dust Suppressant Selection 5
6.1 Soil Properties/Soil Survey 5
6.2 Important Soil Characteristics 5
6.2.1 Grain Size Distribution And Plasticity Index 5
6.2.2 pH
6.2.3 Moisture Content 6
6.2.4 Soil Strength 6
6.2.5 Rate of Compaction 8
7.0 Climatology 8
7.1 Rain 8
7.2 Temperature 8
7.3 Humidity 8
8.0 Environmental Product Selection Criteria 9
9.0 Dust Control Selection 10
10.0 Equipment And Operator Requirements 10
11.0 Site Planning and Preparation 11
12.0 Product Application 11
12.1 Application of Polymer Type Dust Suppressants 11
12.2 Application of Lignosulfonate Type Dust Suppressants 12
12.2.1 Method A 12
12.2.2 Method B 13
13.0 Test Bed Selection Criteria 14
14.0 Test Monitoring 14
15.0 Methods For Evaluating Dust Generation 15
15.1 Sedimentation
15.2 Filtration 16
15.3 Photometric Method 16
16.0 Health And Safety 17
16.1 General Guidelines 17
16.2 Guidelines For PVA Solutions 18
16.3 Guidelines For Lignosulfonate Solutions 18
17.0 Maintenance of Treated Roads 18
17.1 Maintenance of Roads Treated with PVA 19
17.2 Maintenance of Roads Treated with Lignosulfonates 19
References 20
Appendix A: Regulatory Agencies Points of Contact A-1
Appendix B: List of Dust Suppressant Suppliers B-1
Appendix C: Photos of Soil Survey Equipment C-1
Appendix D: Dust Control Selection Key Field Guide D-1
Appendix E: Photos of Application Equipment E-1
Table 1: CBR Values and Compaction Equipment for Various Soil Types
Page 7′
1.0 INTRODUCTION
Wheeled and tracked vehicle operation on dry, unsurfaced landscapes creates tremendous amounts of fugitive dust as soil particles are dislodged and carried into the atmosphere through wind action. During wet weather, these dislodged soil particles are subject to water erosion, which has the potential to carry them into surface waters and thereby reduce water quality and create sedimentation problems for streams and wetlands.
Fugitive dust generated from helicopter, wheeled, and tracked vehicle training exercises has the potential to create many different problems. Most notable of these are associated with safety, air quality, increased military vehicle maintenance requirements, and tactical considerations. Dust clouds generated from helicopter landing pads and tank trails impair the visibility of military vehicle operators and increase the likelihood of accidents and· injury. Excessive dust from tank trails acts as a respiratory irritant to military operators and is considered a safety and air quality hazard when it drifts into nearby housing and administrative areas or onto adjacent highways and streets. Excessive wear and tear on military vehicles and aircraft results from the intrusion of dust into engine and turbine compartments, air-filtering systems, and other sensitive mechanical and electrical components. Finally, dust generated from helicopter and tank movement provides an unmistakable signature to enemy forces in a tactical scenario.
Historically, numerous products have been developed and used to control dust on unsurfaced landing zones, roads, and trails. Some products, such as used motor oils, industrial manufacturing wastes, and other petroleum based derivatives, have damaging environmental effects and their use is now prohibited. However, recent developments in dust-control technology have provided a number of environmentally safe materials similar in cost, efficacy, durability, and maintenance requirements, especially on unimproved roadways where rougher terrain may make traditional road maintenance more difficult and costly.
2.0 USER DATA PACKAGE FOR POLYMER AND LIGNOSULFONATE TYPE DUST SUPPRESSANTS
The dust control measure of most common resort is that of applying a material to the dust source that prevents the dust emissions. Products currently on the market available for use are too numerous to mention by name but most products fall into one of the following generic material categories:
The information in this User Data Package (UDP) is intended to provide guidance to Public Work Centers, environmental, and safety managers in the use of polymer and lignosulfonate types of dust suppressants. This UDP discusses the suitability of these dust suppressants, selection criteria, site preparation, product application, product evaluation, and maintenance of treated areas.
3.0 REGULATORY REQUIREMENTS AND PERMITTING ISSUES
Regulations governing construction/demolition activities, feedlot operations, landfill/disposal sites, open areas/staging areas handling and storage of bulk materials, paved roads, and unpaved roads require the permittee to prepare a written dust control plan to the air control agency as part of the permitting process. This plan must identify the measures and strategies to be followed by the permitee in preventing/controlling airborne emissions of particulate matter with diameters equal to or smaller than 10 microns. In addition, dust control measures must be environmentally safe. Any dust control products should not break down and become airborne emissions, nor should they present a threat to ground water, plant and/or animal life. Prior to procurement of a dust control product, consult with the regional air quality and water quality control agencies regarding the potential dust control products under consideration for use.
Air Quality regulations and Water Quality regulations are in potential conflict when it comes to selecting a dust control material. Air quality considerations require that dust emissions be prevented at the source and the use of dust control materials is often required. Water quality considerations require that no material be applied to the soil that will contaminate or damage the water supply.
Water and air quality control agencies sometimes have lists of products on the market that are available for use, but the products named on these lists are neither “approved” nor “not approved”. At the present time, it is possible to select a product from a product list provided by one regulatory agency and that product could be totally unacceptable based on the environmental considerations of another regulatory If a dust control product is environmentally unacceptable for a known reason, the agency can be expected to reject the product or limit its use and advise accordingly. However, the agency will not approve products that it has no reason to reject. Those products may be used to control dust. If a company or public agency submits a product to the water control agency and the water control agency does not reject the product, then the company or public agency remains responsible if it uses the product and later finds that the product is environmentally unsafe.
The use of acceptable product selection criteria, which provide meaningful information about the environmental acceptability of a dust control product, minimizes the possibility of an incorrect decision. The more thorough the product selection criteria, the more information available to help reach an environmentally correct decision. Section 8.0 discusses criteria for selecting dust control products. Appendix A includes points of contact information for various regulatory agencies.
4.0 DESCRIPTION OF POLYMER AND LIGNOSULFONATE SUPPRESSANTS
The primary objective of dust control materials is to prevent soil particles from becoming airborne. PVA and lignosulfonate type dust suppressants, as opposed to other types of dust suppressants, typically do not contain petroleum products and, therefore, are more compatible in sensitive environments and less likely to be rejected by regulatory agencies. PVAs and lignosulfonates are not soil stabilizers that increase the bearing strength of the trafficked area. Therefore, an important factor limiting the applicability of these dust palliatives in traffic areas is the extent of surface rutting that will occur under traffic, especially by tracked vehicles. The effectiveness of the treatment is destroyed rapidly by rutting and any remaining dust palliative is quickly stripped from the ground surface. Appendix B provides a partial list of vendors that supply PVA and Lignosulfonate type dust suppressants.
4.1 Polymer Type Dust Suppressants
Polymer type dust suppressants are generally polyvinyl acrylic (PVA) proprietary emulsions modified with plasticizers, surfactants, and other compounds. The PVA dust control products are suitable for many types of soil and climatic conditions and have been used extensively throughout the United States by various mining industries for dust control on haul roads and The product is supplied in a concentrated form that resembles white latex paint yet, when cured, produces a clear hard surface-binding film that retards dust formation. PVA must be diluted with water before application according to each manufacturer’s recommendation. Generally speaking, the dilution ratios range from 1:1 to 1:7 of product to water. Application rates range between 1/3 to 2/3 gal/yd2• PVA type dust suppressants can be applied with a water truck equipped with spray bars or an asphalt distributor. A clear hard film is produced when cured by drying in approximately 4 hours depending upon ambient weather conditions.
4.2 Lignosulfonate Type Dust Suppressants
The lignin type dust suppressants are derived from an industrial paper making waste product that contains lignin and other carbohydrates in aqueous suspension. However, specific composition depends on the chemicals and processes used to extract the cellulose and the tree type. Lignin acts like a natural cement to bind the fibers of wood together in plants. Consequently, the lignin polymer and wood saccharides act as a glue to bind soil particles together when used in road treatment. The most common process used in extracting lignin from the pulping liquor is the sulfite process. The lignin derivative produced is called “lignosulfonate” and is water soluble. The term Spent Sulfite Liquor (SSL) is used interchangeably with lignosulfonate.
Initially, the aim of lignosulfonate treatment was simply dust-abatement, which was accomplished by spraying light applications of dilute raw lignosulfonate solutions onto dirt roads. The method gained importance when concentrated lignosulfonate was shown to promote the stabilization and consolidation of roadway mixtures. The lignosulfonates act essentially as clay dispersants, making the clay more plastic at lower moisture content which, after compression, leads to a denser, firmer road cap. For this reason, clay is very important component of a good road soil, and a prerequisite for successful road binding with lignosulfonates. Once the road is properly compacted and consolidated, the void spaces between soil particles become minimal, water uptake is greatly reduced and loss of binder by rain leaching is minimized.
Lignosulfonates have been used extensively by the Department of Transportation and in the southwestern United Sates and the forestry industry in the western and southeastern United States for dust control on unsurfaced county and logging roads, respectively. The wide range of soil and climatic conditions encountered in these regions attest to its broad applicability. Generally speaking, a good soil mixture should contain particles less than 1 inch in diameter and should be composed of about 40 percent each of coarse and fine aggregate and of about 20 percent of clay and silt. An addition of at least 10 percent clay to a pure sand soil is recommended. If this is not feasible, using a lignosulfonate mixture of 50 percent total solids and 50 percent water is recommended.
The lignin-based dust suppressants are available in dry and concentrated liquid forms and must be mixed or diluted with water before application according to each manufacturer’s recommendation. The dilution ratios typically range from 1:1 to 1:7 of product to water.
Application rates range between 1/3 to 2/3 gal/yd2 Most lignosulfonates type dust suppressants dry in approximately 4 hours depending upon ambient weather conditions. Lignin can be applied with a water truck equipped with spray bars or asphalt distributor capable of metered application at rates generally between 0.45 and 0.65 gallon per square yard.
Lignosulfonate solutions are noted to be corrosive to aluminum and its alloys due to the presence of caustic compounds used in the extraction process. Some products such as calcium carbonate can be added to raise the pH to minimize corrosivity. The carbonate is also noted to reduce the solubility of the compound and thus prolong the dust suppressing effect. The addition of dichromate to lignosulfonate in a chrome-lignin soil stabilization study revealed that the mixture formed a gel and acted as a waterproofing agent. The study also reported an increase in stability of the soil.
5.0 DUST SUPPRESSANT SUITABILITY FOR VARIOUS FIELD APPLICATIONS
Due to differences in traffic type and volume, soil types, and roadway/trail surface characteristics, product performance can and will vary. Neither lignosulfonate nor PVA type dust suppressants have successfully withstood traffic from track-equipped vehicles.
Lignosulfonates have successfully withstood the following field applications:
PVAs have successfully withstood the following field applications:
6.0 CONSIDERATIONS FOR DUST SUPPRESSANT SELECTION
6.1 Soil Properties/Soil Survey
Soil surveys can help in evaluating the properties that effect the maintenance of roads open areas treated by dust suppressants. Among the important soil properties described in soil surveys are:
Natural soil drainage
Permeability
Infiltration rate
Flood hazard
Soil structure
Shrink-swell potential
Erodibility
Acidity and alkalinity
Load bearing capacity
Slope
Sand, silt, and clay content
Corrosivity
In addition, soil properties are key factors when selecting a suitable dust control product for unpaved roadways. Soil composition, grain size distribution, pH, and moisture content are general characteristics that are requested by the dust suppressant applicator to determine whether a given product will be effective, and to determine optimal application rates and methods.
6.2 Important Soil Characteristics
6.2.1 Grain Size Distribution And Plasticity Index
As previously mentioned, lignosulfonates act essentially as clay dispersants, making the clay more plastic at lower moisture content, which, after compaction, leads to a denser, firmer road surface. For this reason, soil fines are an important component of the road surface material and a prerequisite for successful road binding with lignosulfonates.
One should compare the aggregate particle size distribution with the recommended aggregate mix to achieve a good surface course. Without sufficient fines the larger size aggregates cannot bind together into a tight matrix, and thus aggregate pullout is easier. The recommended aggregate particle size distribution percent passing No. 40 (425-µm) and No. 20 (75-µm) standard sieves are between 25-45 percent and 10-25 percent, respectively. For soils lacking in sufficient fines, such as sandy soils, one may either add clay to the aggregate mix or use a PVA type dust suppressants. Appendix C includes a photo of a soil sieve for field use.
6.2.2 pH
The pH of the soil should be determined before selecting a particular dust suppressant since some dust suppression products break down in an alkaline soil. Appendix C includes a photo of a soil pH meter.
6.2.3 Moisture Content
Some manufacturers claim that their PVA and lignosulfonate type dust suppressants can be applied on dry soil. However, most manufacturers agree that product penetrability is increased if the soil has been prewetted. For dry soils, prewetting with water breaks the soil’s surface tension and allows for a more uniform coverage of the dust control product.
6.2.4 Soil Strength
The California Bearing Ratio (CBR) test was recommended to the American Society for Testing and Materials (ASTM) as a standard test and is now designated as ASTM 1883. The CBR estimates the bearing value of sub-bases and sub-grades. Sub-bases are the road bed excavations while the sub-grades are the fill material laid on the sub-bases up to where the road surface is applied. The stronger the sub-base, the more likely the treated road will resist rutting and washboarding. The test consists of pushing a standard plunger into the soil at a constant rate and measuring, in suitable intervals, the force required in order to maintain that rate. The graphical load-penetration relationship can be drawn and the loads corresponding to standard penetrations are expressed as ratios (percent) of standard loads. The accepted percentage is known as the CBR value of the soil in the condition is which it was tested. The CBR value can be regarded as an indirect measure of the shear strength of the soil, but it cannot be directly related to shear strength parameters. Table I shows the CBR values (compacted density) for various soils and the type of compaction equipment required on the sub-base to achieve that CBR value.
Appendix C includes a photo of a field CBR jack. The jack consists of a corrosion protected body that houses an enclosed worm and wheel gear. The carefully selected gear ratio provides a hand wheel speed that can be comfortably maintained particularly with soils of a high CBR value. A quick release device in the screw jack allows for rapid adjustment of the plunger prior to the test. Final adjustments are then carried out via the handwheel.
Major Soil Division | Soil Description | Drainage
Characteristics |
Compaction Equipment | Field CBR (Compacted
Density) |
Gravel and gravelly soils |
Gravel or sandy gravel,
well graded |
Excellent | Crawler-type tractor, rubber-tired equipment,
steel-wheeled roller |
60-80 |
Gravel or sandy gravel,
poorly graded |
Excellent | Crawler-type tractor, rubber-tired equipment,
steel-wheeled roller |
35-60 | |
Gravel or sandy gravel,
uniformly graded |
Excellent | Crawler-type tractor, rubber-tired equipment | 25-50 | |
Silty gravel or silty sandy gravel | Fair to poor | Rubber-tired equipment, sheepsfoot roller | 40-80 | |
Clayey gravel or
clayey sandy gravel |
Poor to
practically impervious |
Rubber-tired equipment, sheepsfoot roller | 20-40 | |
Sand and sandy soils |
Sand or gravelly sand,
well graded |
Excellent | Crawler-type tractor, rubber-tired equipment | 20-40 |
Sand or gravelly sand,
poorly graded |
Excellent | Crawler-type tractor, rubber-tired equipment | 15-25 | |
Sand or gravelly sand,
uniformly graded |
Excellent | Crawler-type tractor, rubber-tired equipment | 10-20 | |
Silty sand or silty gravelly sand | Fair to poor | Rubber-tired equipment, sheepsfoot roller | 20-40 | |
Clayey sand or clayey gravelly sand | Poor to
practically impervious |
Rubber-tired equipment, sheepsfoot roller | 10-20 | |
Low compressibility soils |
Silts, sandy silts, gravelly silts,
or diatomaceous soils |
Fair to poor | Rubber-tired-equipment, sheepsfoot roller | 5-15 |
Lean clays, sandy clays, or gravelly clays | Practically impervious | Rubber-tired-equipment, sheepsfoot roller | 5-15 | |
Organic silts or lean organic clays | Poor | Rubber-tired-equipment, sheepsfoot roller | 4-8 | |
High compressibility soils |
Micaceous clays or
diatomaceous soils |
Fair to poor | Rubber-tired-equipment, sheepsfoot roller | 4-8 |
Fat clays | Practically
impervious |
Rubber-tired-equipment, sheepsfoot roller | 3-5 | |
Fat organic clays | Practically
impervious |
Rubber-tired-equipment, sheepsfoot roller | 3-5 |
7
6.2.5 Rate of Compaction
A penetrometer is used to assist identifying soil types using the most common soil behavior classifications by determining the rate of compaction for any soil at different depths. To use, constant pressure is applied on the handgrips to push the rod and cone into the soil. Resistance of the soil is determined by dividing the reading by the surface area of the selected cone. A drag counter records the highest measurement. A photo of a handheld penetrometer is included in Appendix C.
7.0 CLIMATOLOGY
The climate will have a varying influence on the performance of dust suppressant products depending on the product’s chemical and physical properties. For example, products, such as lignosulphonates and uncured PVA, are soluble and may leach out under a heavy rain decreasing their effectiveness as well as posing a threat to contaminate groundwater. Due to potential impact on product performance, rain, temperatures, and humidity are discussed below.
7.1 Rain
Precipitation, even if infrequent, is important to product application for the following reasons:
DO NOT ATTEMPT TO APPLY DUST SUPPRESSANTS DURING OR BEFORE A RAIN. IF RAIN IS PREDICTED WITHIN 24 HOURS OF THE ANTICIPATED COMPLETION OF THE DUST SUPPRESSANT’S DRYING OR CURING TIME, THE PROJECT SHOULD BE POSTPONED.
7.2 Temperature
Temperature is important to product storage and application because many dust suppressant products are liquid in the stored state and are affected by extreme temperature. Specific issues that temperature may influence are:
According to dust suppression/soil stabilizer distributors, some suppressants require a minimum temperature above 63 degrees Fahrenheit to cure. Cure time is also influenced by temperature as it affects evaporation and chemical reaction. Desert temperatures can fluctuate dramatically reaching as high as 118 degrees F and as low as 18 degrees F.
7.3 Humidity
As opposed to other products that are hygroscopic and require a minimum of 30 percent humidity, lignosulfonate and PVA type dust suppressants may be used in low and high humidity conditions. One can expect curing times to increase or decrease in high or low humidities, respectively.
The environmental safety of a dust control product may be ascertained by asking a series of questions that can provide the basis for determining the degree to which a product may be regarded as environmentally acceptable or unacceptable:
By using questions like these as selection criteria, one can be relatively sure that proper environmental consideration is given to the selection of a dust control product. It is extremely unlikely that any dust control product will offer a favorable response to all of the questions. Depending on the situation, some of the questions are of primary importance and others are secondary. For example, it would be environmentally incorrect to select a water soluble dust control product to treat a roadway next to a trout stream. A dust control product that emits odoriferous vapors would not be the correct choice of product to control dust in a populated area. Once the responses to the selection criteria questions are determined, an environmentally correct decision is possible.
In any event, using acceptable selection criteria provides a method of rating or ranking the environmental acceptability of given dust control products. The use of acceptable selection criteria greatly reduces the possibility of inadvertently using a product that causes environmental damage.
9.0 DUST CONTROL SELECTION
The U.S. Anny Environmental Center (USAEC) has developed a Dust Control Guidance and Technology Selection Key and the Dust Control Selection Key Field Guide. The key was designed to help military installations evaluate solutions for dust control problems.
It recommends categories of chemical dust palliatives according to traffic volume, climatic factors, and soil types and textures. The categories include lignosulfonate and polymer type dust suppressants as well as other dust palliative types.
A copy of the Selection Key and Field Guide is included in Appendix D. Copies of the Selection Key and Field Guide may also be obtained by contacting the U.S. Army Environmental Hotline at (800) USA-3845, DSN 584-1699. The Web-based versions may be viewed at the following web site:
http://aec.army.mil/prod/usaec/et/conserv/conserv.htm
10.0 EQUIPMENT AND OPERATOR REQUIREMENTS
The following lists and briefly describes the equipment requirements for applying PVA and lignosulfonate type dust suppressants:
Experienced operators are required for the motor grader, compaction equipment, water truck, and asphalt distributor. A civil engineering technician or an engineer familiar with dust control material application should be present when the material is being placed.
Photos of the required application equipment are included in Appendix E.
11.0 SITE PLANNING AND PREPARATION
The following is a general procedure for planning the application of dust control products to an area:
1) Determine the area to be treated (square yards).
2) Evaluate the surface soils and classify according to Unified Soil Classification Consult TM 5-830-3/AFM 88-17, Chap.3 (Headquarters, Departments of the Anny and Air Force 1987) and with product manufacture representatives to determine suitability of treatment method and application rates.
3) Select a suitable dust suppressant that is compatible with the soil and the environment. Section 0 discusses basic methodologies to test and evaluate the effectiveness of dust suppressants if a field study is required prior to product selection.
4) Order enough material to treat the m:ea.
5) Plan the project so equipment and personnel are available to accomplish the preparation and application procedures in an orderly step-by-step process.
6) Select a storage area for the materials near the project
7) Locate a convenient water The water point should be located and a large capacity (4,000-5,000 gallons) water distributor is recommended. If a stream or pond is used for the water point, a pump will be required to fill the distributor. If . prewetting is performed, any water that has ponded should be broomed or swept away before product is applied.
12.0 PRODUCT APPLICATION
12.1 Application of Polymer Type Dust Suppressants
The following lists a general construction procedures for applying polymer type dust control products to an area. Actual procedure may vary according to specific product manufacturer’s recommendations. For example, compaction may be required before and/or after the application step or the prewet step. Some products do not require the prewet step or/and others may require two to three coats in varying concentrations.
Testing may be necessary to determine the procedure that works best for a particular soil type.
12.2 Application of Lignosulfonate Type Dust Suppressants
The following subsections describe two methods of general construction procedures for applying lignosulfonate type dust control products onto an area.
12.2.1 Method A
12.2.2 Method B
13.0 TEST BED SELECTION CRITERIA
Sometimes testing several products in the field is necessary to determine the product best suited for a particular soil and/or field operation. Selecting an appropriate test site is critical since many variables can skew the test results. If at all possible, a straight level unpaved stretch of road with uniform soil is desired. Section the roadway into 0.3-mile long sections in preparation for application of dust-control treatments. Prior to dust control agent application, all roadway and tank trail segments should be graded to remove excess surface material, potholes, and washboarding. Install magnetic traffic counters to record traffic volume. This data can be used to relate traffic volume to dust control agent effectiveness and durability. Following grading and traffic counter installation, each 0.3- mile-long roadway and tank trail section should be treated with each of test dust suppressants following the manufacturer’s application recommendations.
The wind conditions can also have an influence on the performance evaluation of dust suppressant and soil stabilizers. Wind speed and direction are key elements of importance since any test area evaluated will have some exposure to fugitive dust transported by wind. Field tests will require an evaluation of adjacent land use based on their potential to contaminate sites with fugitive dust. Wind speed is also important from the standpoint that it affects soil lift and dust generation. These variances occur when wind blows migrate dust into or out of the proposed test bed area, and should be considered when evaluating different test products. Generally speaking, the optimum test bed or road section orientation should be perpendicular to the prevailing winds.
14.0 TEST MONITORING
Following application to a roadway, select a control speed (i.e. 30 mph) and post the desired speed sign along the test roadway. Set up a traffic counter to record traffic volume and allow normal traffic to resume. Immediately begin dust control/traffic test monitoring of each treatment in each road way section for three to six months. Record traffic volume via the traffic counter and use data to estimate monthly traffic volume as it relates to product durability over time. Road test sections should be inspected and monitored after each rain event.
The performance of each dust control material should be documented by recording visual observations in a field notebook as traffic tests are being conducted and after the· completion of tests. Visually inspect traffic as it passes along the road test sections, recording when dust generation begins. Note when ruts, potholes, and washboarding begin to develop. It is also suggested that the pilots of aircraft that operate on treated runways be interviewed to determine the extent of dust control on assault runways.
Normally a treated area can be expected to be effective for approximately six months to one year, but the effectiveness of any dust control product is largely dependent upon weather conditions and the volume and type of vehicles that traffic the treated area.
15.0 METHODS FOR EVALUATING DUST GENERATION
Commercial and military activities have employed numerous products in an attempt to control dust generated from vehicles traveling over unpaved roadways. Frequently, dust suppressant products are selected based on one or more of the following criteria: manufacturers’ literature review, product’s past performance, bench scale testing, and field evaluation. Numerous tests and evaluations have been performed to quantify dust generated from vehicles traveling over unpaved road. Testing the best product candidates can help determine the best product for a given set of soil and climate conditions. Numerous methods used to evaluate dust generation includes one or more of the following methods: sedimentation, filtration, or photometric. The following is a brief description of the limitations and advantages of these three methods. These methods used to evaluate the effectiveness of dust suppressants vary from simple to complex and inexpensive to expensive. It is possible to employ these methods of evaluation periodically throughout the duration of a test. Depending upon the product and test situation, it may only be necessary to evaluate product performance once a week for three months or once a month for a year. For areas requiring highly advanced methodologies to evaluate dust generation, one may refer to Test Evaluation of Dust Suppression Product Conducted for Marine Corps Air Ground Combat Center, a site specific report which is included in the list of references on page 20 of this UDP.
15.1 Sedimentation
Sedimentation is a fairly inexpensive method to determine dust generation rates. The method, which depends on gravitational forces to settle out lifted dust, is a mass measurement technique using open top collectors such as cans or glass jars to trap dust particles. These containers are positioned at various distances from a treated roadway. After an exposure for a set period of time, typically 30 days, the particulate in each container is weighed and compared to other treated test areas. Variables that skew direct comparison exist in open field studies (and uncontrolled traffic), where different products are laid in parallel or adjacent to one another. In general, these variables have been the cause of dispute. The concern is not so much with the capture collection method, but with the uncontrolled source of the dust captured. Influencing factors are cross contamination from adjacent test plots, product carry-over from adjacent areas, variations in soil, and unequal exposure to rain water run-off. Other variables such as fugitive dust, traffic flow, braking, variable vehicle speed, weight and shape of vehicles can also skew direct comparison.
The following describes a simple sedimentation test procedure:
Following application to roadway, select a control speed (i.e. 30 mph) and post along test roadway. Place a tared, oil-coated dust collection pan at each comer of the helipad to be evaluated. Place on each side of the treated roadways, tared, oil-coated dust collection pans between 15 and 20 feet away from the center of the road or trailing positions that avoid possible contamination from adjacent treatments. Allow normal traffic to resume and begin recording counter data.. After the set test period has passed, retrieve dust collection pans and reweigh, and determine the amount of dust collected.
Relate the amount of dust collected to the traffic volume to estimate product durability overtime.
15.2 Filtration
Quick results can be obtained by using the filtration method to determine dust generation. Filtration basically consists of high volume air samplers that collect dust by using a vacuum pump and filter medium. The air samplers should be capable of accurately measuring airborne particulate matter utilizing 8 in. by 10. in filter paper that traps particles a small as 0.01 micron size. Mount the samplers on a tripod positioning the filter paper 42 inches above the ground. Filter systems can also be mounted on moving vehicles.
The main concern with past tests performed using filtration technology is the variability of traffic and wind conditions on sections of treated roadway. Dust capture will vary because ambient wind conditions are not uniform, causing variability at the dust collection capture point. Costs are high, since several vacuum pump systems must be placed at various locations around the test strips so that wind changes can be modeled into dust capture mass determination. To avoid modeling, some activities have mounted a vacuum system _close to the tire of a test vehicle. This method has provided some quantitative results.
The following describes a filtration test procedure:
Following application to roadway, select a control speed (i.e. 30 mph) and post along test roadway. Place a filtration system at each comer of a helipad to be evaluated. Place filtration systems at the midway point of each test section of roadway, one on each side of the road. Begin recording counter data and running the air samplers. Samplers are typically run for periods of 2 to 4 days. Allow normal traffic to resume. After the predetermined test period has passed, retrieve the tared filters, and determine the amount of dust collected. Relate the amount of dust collected to the traffic volume to estimate product durability over time.
15.3 Photometric Method
The photometric method is based on measuring light transmission through the dust cloud created by a passing vehicle on an unpaved road. Opacity measurements are taken right after passage of a control vehicle across a select point. Generally speaking, the method is subject to the same inaccuracy as the previous two and is subject to additional uncertainties caused by the equipment’s response to wind speed, wind direction, sunlight intensity and cloud cover.
Videographic images can be used during every traffic test to evaluate and quantify the degree of dust control afforded by the different agents. The following describes a videographic test procedure:
Following application to roadway, select a control speed (i.e. 30 mph) and post along test roadway. On the shoulder of the treated roadway section, install a six-foot long board vertically along the edge of each roadway test item at the center of the item. Paint the board white and mark with black symbols and numbers so the height and density of the dust clouds generated by the traffic vehicles can be determined. Begin recording counter data and allow normal traffic to resume. Use a video camera and 35 mm camera to obtain video tape and photographs of dust obscuration levels immediately preceding and at five seconds after controlled vehicle traffic passes the white board. Digitize the images and analyze for level of obscurity using computer image processing techniques to determine changes in the mean value level of images due to dust. Relate the dust generation levels.
16.0 HEALTH AND SAFETY
16.1 General Guidelines
The following guidelines should be followed when handling any dust suppressant:
Carefully read the Material Safety Data Sheets (MSDS) for the product to determine whether the dust suppressant product may pose a risk to human health and the environment. Although many products are considered biodegradable, it is advised to check with the manufacturer and MSDS. Comparing analytical tests on samples of untreated soil and treated soils can determine the background concentrations of metals in the soil and the concentration of any organic solvents in the dust suppressant product.
Some of these tests may include Total Threshold Limit Concentration (TTLC), Soluble Threshold Limit Concentration (STLC), Total Organic Carbon (TOC).
16.2 Guidelines For PVA Solutions
The following are special guidelines for handling PVA solutions:
16.3 Guidelines For Lignosulfonate Solutions
The following are special guidelines for handling lignosulfonate solutions:
17.0 MAINTENANCE OF TREATED ROADS
Normally a treated area can be expected to be effective for approximately six months to one year, but the effectiveness of any dust control product is largely dependent upon weather conditions and the volume and type of vehicles that traffic the treated area.
Generally speaking, treated roads should be inspected monthly and after each rain event. Traffic wear over a period of time may result in formation of potholes and raveling of the treated surfaces. This is especially true when water accumulation occurs on the surface by an improperly shaped crown or when the aggregate is insufficiently mixed with binding soil. Maintaining treated roads can vary from product to product. The following subsections address methods to repair damaged roads.
17.1 Maintenance of Roads Treated with PVA
Surface aggregate material can reduce the effectiveness and durability of some polymers. Vehicle movement across aggregate covered surfaces causes surface abrasion and shifting, which can quickly destroy the sealing/binding characteristics associated with a particular polymer. Polymers are surface sealers and binders requiring a relatively smooth, stable road surface to maximize performance. In addition, PVA is biodegradable and will dissolve from a treated soil area with continued exposure. For low traffic areas, a second application at one-half the rate of the first application should be planned following 10 to 14 months of service. For high traffic areas, a similar type application should be planned following six months of service.
For roads treated with PVA type dust suppressants, the preferred method for minor repair is patching rather than total regrading or blading. Patching mixtures should have a composition similar to that of the road surface. To repair potholes fill the holes with a 1 to 1 product to water mix. Fill the holes with dirt and allow the dirt to absorb the polymer until saturated. After saturation is complete, tamper the dirt down. Follow with a topcoat of polymer and allow the road to dry.
17.2 Maintenance of Roads Treated with Lignosulfonates
For roads treated with lignosulfonates, the preferred method for minor repair is patching rather than total regrading or blading. Patching mixtures should have a composition · similar to that of the road surface. Use a lignosulfonate solution to moisten the bottom of the potholes. Fill the pothole with a patching soil-binder mixture and compact. The patching mixture should contain at least 1 percent lignosulfonate solids based on soil weight.
If raveling, pothole formation or dusting becomes excessive, the surface must be reworked. This is best done after a rain, or after pretreatment with water or a lignosulfonate solution to soften the surface. The road surface is then best cut to the bottom of the potholes, and the loose material treated as suggested under Section 12. Grading of the dry, treated road loosens the bonded road surface and may create some dusting. Hence, grading should only be done when general shaping, or major repair is needed.
References
Addo, J.Q. and Sanders, T.G. Effectiveness and Environmental Impact of Road Dust Suppressants. Department of Civil Engineering, Colorado State University, Fort Collins CO, March 1995.
Anguiano, G., Sandoval R., and Webb T. Evaluation of Dust Suppression Products Conducted for the Marine Corps Air Ground Combat Center, Twentynine Palms, CA. Site Specific Report SSR-2343-ENV, Naval Facilities Engineering Service Center, Port Hueneme, CA, Nov. 1997.
Gebhart, D.L. and Hale, T.A. Dust Control Material Performance on Unsurfaced Roadways and Tank Trails. V. S. Army Construction Engineering Research Laboratories, Champaign, IL, Sept. 1996.
Grau, R.H. Evaluation of Methods for Controlling Dust. Technical Report GL-93-25,
U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS, Sept. 1993.
Grau, R.H. Dust Proofing Unsurfaced Areas. Miscellaneous Paper GL-92-9, U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS, March 1992.
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APPENDIX A
REGULATORY AGENCIES
POINTS OF CONTACT
APPENDIX B
LIST OF DUST SUPRESSANT SUPPLIERS
APPENDIX C
PHOTOS OF SOIL SURVEY EQUIPMENT
APPENDIX D
DUST CONTROL SELECTION KEY FIELD GUIDE
APPENDIX E
PHOTOS OF EQUIPMENT
Copyright Soilworks, LLC 2003-. All Rights Reserved. Soilworks®, Soiltac®, Gorilla-Snot®, and Durasoil®are registered trademarks of Soilworks, LCC.
Copyright Soilworks, LLC 2003-. All Rights Reserved. Soilworks®, Soiltac®, Gorilla-Snot®, and Durasoil® are registered trademarks of Soilworks, LCC.