Road Stabilization

Erosion Control

Environmental, Health & Safety Information

Recent field testing of PennzSuppress^® D proves the product to be highly effective for controlling dust from unpaved roads. Dust caused by vehicles traveling on unpaved roads has been identified by United States Environmental Protection Agency (US EPA) as a health and environmental concern.

According to recent US EPA survey data, unpaved roads account for 28% of the nationwide dust emissions formally known as PM-10 (dust particles 10 microns or less). Recent US EPA National Ambient Air Quality Standards have redefined particulate emissions using a PM-2.5 standard (dust particles 2.5 microns or less). PennzSuppress^® D has been field tested by the independent Midwest Research Institute (MRI) and found to be very effective at reducing PM-2.5 and PM-10 dust emissions from unpaved roadways.

Known for its success in developing numerical emission models and field-particulate measurement methods for the U.S. Environmental Protection Agency, the not-for-profit MRI began its PennzSuppress^® D testing in April, 1997. Institute researchers chose an open-pit copper mine and a county road near Tucson Arizona as test sites. Cactus Transport, Inc., the PennzSuppress^® D distributor for Arizona, prepared the road sites for testing by both stabilizing and topically applying the product to test sections.

THE SCOPE OF WORK

The purpose of the field testing was to determine the long-term, average control efficiency expected through regular use of PennzSuppress^® D on the road surfaces treated. The test program captured the following information at each site tested:

• mean vehicle speed
• mean vehicle weight
• average traffic rate

• intensity of applied product (volume of diluted product per unit of road surface area)
• dilution ratio of product
• frequency of product reapplications (number of applications per unit time)
• application method

• materials of construction for the road surface and subgrade
• crowning, curves and other physical layout variables

• precipitation
• wind speed, direction
• temperature
• barometric pressure

Emission Measurement Technique

The emission testing used the exposure profiling method to quantify mass emissions from the test roads in both controlled and uncontrolled conditions. Exposure profiling uses a direct mass-balance calculation scheme similar to stack testing methods rather than relying on an uncalibrated dispersion model to indirectly back-calculate an emission rate.

The method required simultaneous measurement of particulate concentrations and wind speed at various points over the effective height of the plume of suspended particulate matter. Background concentrations are measured upwind of the test road.

Sampling Equipment

Sampling equipment consisted of a high-volume cyclone operated at 40 cubic feet per minute (cfm) staged downwind of the test area at heights of 1.3, 2.7, 4.1, 6.0 meters. Additionally, a high-volume cyclone followed by a 3-stage cascade impactors were operated at 20 cfm and staged upwind and downwind of the test area at heights of 1.3 and 4.1 meters. This equipment is consistent with that used to develop the particle size multipliers used in EPA's AP-42 predictive emissions factor equations for paved and unpaved roads. The aerodynamic particle sizes measured by this equipment included 15, 10.2, 4.2, and 2.1 microns.

Test Sites

Two application methods were evaluated on PennzSuppress^® D treated roads on three unpaved roadways. Detailed information on application methods for each test site is provided below.

• Week 1 - One 0.25 gal/yd² application of a 9:1 dilution of PennzSuppress^® D (nine parts water to one part PennzSuppress^® D concentrate).
• Week 2 - One 0.25 gal/yd² application of a 9:1 dilution of PennzSuppress^® D.
• Total ground inventory of PennzSuppress^® D concentrate after treatment was 0.15 gal/yd².

• Week 1 - Three 0.25 gal/yd² applications of a 9:1 dilution of PennzSuppress^® D.
• Week 2 - Three 0.25 gal/yd² applications of a 9:1 dilution of PennzSuppress^® D.
• Week 7 - Maintenance application of three 0.25 gal/yd² applications of a 9:1 dilution of PennzSuppress^® D.
• Total ground inventory of PennzSuppress^® D concentrate after treatment was 0.225 gal/yd².

• Road was bladed and sprayed with 0.5 gal/yd² of a 4:1 dilution of PennzSuppress^® D then blade-mixed.
• Second spray of 0.5 gal/yd² of a 4:1 dilution of PennzSuppress^® D then blade-mixed.
• Road surface was static rolled followed by vibratory rolling.
• Final topical application of a 0.5 gal/yd² of a 4:1 dilution of PennzSuppress^® D.
• Total ground inventory of PennzSuppress^® D after treatment was 0.3 gal/yd².

TEST RESULTS

Field testing spanned a period of approximately 120 days with traffic counts ranging from 35 to 200 vehicles per day and with cumulative vehicle traffic totaling up to 7,000 passes. Airborne PM-10 and PM-2.5 dust particles generated by vehicle traffic on treated and untreated road surfaces were sampled. The control efficiency was calculated by comparing dust emission measurements from the PennzSuppress^® D treated roads to the untreated roads.

Control efficiency results are illustrated in the Figures 1 through 3. At the end of 5,500 to 7,000 vehicle passes, PennzSuppress^® D still controlled PM-10 emissions in the range of 86% to 98% and controlled PM-2.5 emissions in the range of 83% to 97%. The field data indicated that PM-2.5 control efficiency was typically within 4% ± of the PM-10 control efficiency.

The control efficiency data from the field testing was compared to past studies on dust palliatives. According to MRI:

The average control efficiencies of PennzSuppress^® D are of greatest interest from a control strategy development standpoint, because they determine the emission reductions achievable with this product.

MRI has confirmed what many PennzSuppress^® D users have already experienced. PennzSuppress^® D is highly effective in reducing dust caused by vehicle traffic on unpaved road surfaces.