Road Stabilization Report

Tooele County, Utah

June 2001 – October 15, 2002

Rod Thompson – Road Engineer, Tooele County, UT

Raymond Johnson – Director of Public Works, Tooele County, UT

Jon Sedgwick – Director of TerraZyme Development, Nature Plus, Inc.

GENERAL USE OF TERRAZYME SOIL STABILIZER IN ROAD BASE REHABILITATION AND UNSURFACED ROADS

1. INTRODUCTION

This work discusses the use of TerraZyme soil stabilizer and its application in the infrastructure of unsurfaced roads. It summarizes work on Benmore road constructed near Vernon, Utah County, Utah, USA during late June of 2001 and subsequent work completed on additional roads. The purpose was to demonstrate the broad use of TerraZyme soil stabilizing technology in municipal, state and National Forest Service projects, and to discuss measured results.

TerraZyme is used world-wide in strengthening of base layers of unsurfaced roads or soil roads, in base layers and sub-base layers of highways covered with asphalt material, with recycled pavement, in surfaced and unsurfaced pavements of urban streets, shoulders of highways, restoration of pavement of irregular stones and on forest highways. Among the soil materials stabilized by TerraZyme are sandy clay, silty clay, sandy silt, plastic and non-plastic clay, sandy loam, fine loam, loam mixed with clay, soil mixtures with milled recycled asphalt pavement, among others.

2. CONCLUSIONS

After evaluation of this project using TerraZyme stabilization of soils, it was concluded that the stabilizer promotes the following benefits versus non-treated soils:

Increases in CBR% improved the capacity of the road surface to support greater vehicle loads. The average untreated sub base CBR was 18-22% on the initial Benmore road sections. The CBR of TerraZyme treated sections averaged 79% after six weeks of curing and the most recent data of 10-15-02 shows an average CBR of 134% for road sections treated with TerraZyme. This increase in resistance has greatly reduced the commonly seen surface problems of rutting, potholes, wash boarding and other deformations.

Minimizes the loss of gravel from erosion or abrasion by the traffic on the soil roadways, preserving more closely the original transverse sections and slopes; reduces the ongoing cost of gravel replacement, including its transport and spreading; improves safety by preventing the accumulation of loose surface gravel that reduces surface integrity and prevents contact between tires and firm surface during braking, acceleration and turning – a common cause for loss of vehicle control on graveled road surfaces.

Impedes the widespread occurrence of dust from loose fine material in the surface of the soil roadways; which is becoming a health and cleanliness concern. Dust reductions of about 75% occur with stabilization of the road surface.

Reduces the quantity of construction materials purchased and transported for road repairs and maintenance by upgrading and improving lower quality in-situ soils, making them suitable for local road use.

It is recognized that successful treatment of locally available soil materials at the road sites will provide an economic solution to minimize the project maintenance cost, without depriving road function and durability. This work demonstrates that this new concept of stabilization of soils will

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provide important savings in the construction costs and maintenance costs of roads: rural, access, and farm unsurfaced roads.

3. BACKGROUND

The decreasing availability and growing cost of acquiring road construction materials is forcing engineers to consider more economically methods of building highways using locally available soils that may not fall within specifications. The situation is made more critical by the growing demand for roadways in underdeveloped and rural areas. In addition, pressures in industries, such as mining, agriculture, forest, and others to minimize production costs, are requiring the construction of roads with suitable quality, but lower maintenance costs while minimizing the harmful impact to the environment of production and use of crushed aggregate and historical mineral stabilizers in road construction. An economical solution to reach these objectives has presented itself here for evaluation - the stabilization of soils with bio-enzymes. Appendix H. provides more information on this technology.

A survey of current road conditions in Tooele county reveals typical problems associated with roads constructed of round gravels and cobbles, including wash boarding, material loss, loose surface gravel potholes and dust. These conditions degrade the utility of the road surface, increase maintenance costs and cause accidents through loss of a firm surface at higher speeds. Ruts and potholes can become severe during wet weather. See Appendix A for dry weather photographs of existing, unstabilized roads. Note the common accumulation of loose aggregate and rutting on the existing road surface. Loose material that is moved from the surface to the borrow no longer protects the road. But, the presence of unsecured aggregate and loss of friction are a safety concern for drivers.

Additionally, materials for roads that meet the necessary construction standards are becoming more expensive and scarce. Frequently, it is required to import materials from another areas resulting in great transport distances and consequent increases in the cost of the project. Often when lower quality materials are used in unsurfaced or soil highways, they exhibit unsatisfactory effects from vehicles loads or humidity conditions.

For many roadways, especially with low traffic volume, as rural, local and capillary roads or even high traffic highways, the local soil contains a high percentage of fines, a high plasticity index and do not have appropriate soil characteristics. However, if these soils can be upgraded by stabilization, they can be used successfully to supply material for bases and sub-bases.

The Tooele County Public Works used graders with sacrifiers to open up the road surface, to a depth of 6 to 8 inches (15 to 20 cm.), to mix the soil well and prepare a loose bed for TerraZyme treatment. The TerraZyme 11X at dosage was mixed into the water tanks and this solution distributed well over the bed surface to bring it to about Optimum Moisture Content. The treated soil was mixed well with the graders and compacted with a 10-ton smooth drum roller, using vibratory and static passes. See Appendix B for an example sequence of photographs of TerraZyme applications steps.

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4. MEASUREMENT OF RESULTS

Information on the performance of the TerraZyme treated soil structural layers of the Tooele County roads came from measurements in the field with DCP (Dynamic Cone Penetrometer) equipment. Dynamic Cone Penetrometer (DCP) equipment measures the resistance of penetration of a machined cone point into the soil bed from repeated drops of an 8 kg weight. The less the penetration in mm per drop (the less the slope), the greater will be the resistance and the firmness of the soil bed. These values correlate closely with the California Bearing Ratio (CBR%), a primary indicator of the load handling capability of the road to traffic loads. It is well known that road beds with higher CBR readings are less susceptible to pot hole and rut formation and aggregate and fine material loss. Therefore, less maintenance is needed.

5. DEMONSTRATION ROADS STUDY

Four roads were selected in Tooele County for demonstration of the effects and benefits of soil stabilization. They were the Benmore Road, Center Street-Lakepoint, Old Lincoln Highway and Pony Express. These results will be the basis and justification of future, more extended road projects.

Benmore Road

This road was to remain unsurfaced after stabilization. The existing road surface was treated without adding amendment. Experimental road sections on Benmore Road had stabilizer applied at the end of June 2001 and analyzed with the DCP in early September 2001 (after six weeks), and on the 15th of October of 2002.

In late June of 2001, through a effort organized and supervised by Engineer Rod Thompson and County Public Works construction workers and equipment, a segment of about 100 yards of the Benmore road starting from Utah State Road 36 was stabilized using TerraZyme. Conventional construction equipment was used (road grader with scarifying teeth, water truck, and a steel drum roller.

Soil Characteristics

The average characteristics of the material of the base treated with TerraZyme are approximately as shown below. The soil shows good gradation, some of which is a result of gravel added during historical maintenance. The fine material had limited plasticity. The CBR% values of the untreated road soil Base ranged from about 23% to 33%. See Appendix D, Figures 1 and 2 for CBR% data on the untreated Base and Sub Base.

% Passing Screen – Base Material

Atterberg Limits

2” 1” 3/8” No 4 No 10 No 40 No 200 LL LP IP

100 93 82 70 61 51 24 - 19 -

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CBR Improvement

The stabilized sections were measured after 45 days of traffic usage. TerraZyme treatment more than doubled the CBR% values. The monitoring of the CBR in the top 15 cm treated surface, with the DCP, showed an important increase in the load bearing capacity through stabilization. In Appendix D, Figure 2 also shows the CBR values for the upper 15 to 20 cm (6 to 8 inches) of treated soil from 3 different sampling locations on the road, at least 200 feet apart. The lesser slopes on the TerraZyme treated zone indicate less penetration per drop of the DCP weight. The average CBR% is 79% after 6 weeks. This is well above the untreated CBR% values of 23% to 33% for the untreated base on Figure 1. Observation of surface condition indicates a corresponding improvement in durability and surface quality, with few surface defects. Some small depressions were noted. They seemed to be partially filled with loose aggregate. DCP measurements, taken of the stabilized soil, showed good soil stability and firmness. This suggests the cause of the depression to be inadequate mixing of the soil in that surface spot. Below the shallow deformities, CBR values were consistent with other sections.

Elsewhere, good surface hardness was achieved and the efficiency of the enzymatic stabilizer action demonstrated. Further, experience has confirmed reductions in dust levels of about 75% from stabilization by better securing the fine material on the road surface.

Note also on Figure 2 how the penetration per drop slope increases greatly, once the treated zone is exceeded. This indicates less resistance to penetration per drop of the DCP weight. The resistance of the road surface to potholes, ribbing and rutting are strongly correlated to increased CBR increase. The improvement in CBR% is commonly seen through stabilization. This is dramatically seen on the first photograph in Appendix C. One can see where the stabilization was terminated, by the appearance of road defects in the upper road section.

The average value of CBR = 79% for the Benmore Road was reached after 6 weeks. On Figure 3. stake 1 is the location for CBR values after 15 months (June 2001 treatment) with average center values of 97%. In many road projects, stabilization upgrades the local soil, replacing crushed stone with considerable savings in materials, transportation and therefore construction costs. It is important to note also that on photograph 3, Appendix C the lower section was stabilized, whereas the upper section was not. Note the appearance of wash boarding of the untreated section.

During the summer of 2002, more sections of Benmore road were stabilized following the same procedure as used in the initial sections (represented on Figure 3 as stakes 2 to 10). Observations by Utah State University Technology Transfer officials prompted an increase in moisture content at compaction after initial sections of road had been completed using too little water. Additional data were gathered on October 15th, 2002.

Reviewing stake locations completed with too little water (stakes 2 – 6) showed an average CBR of 63% Those completed after increasing water content at compaction (stakes 7 –10) showed average values of 243%. The average CBR of the untreated Control is 20%. This experiences shows the importance of adequate moisture and proper application methods by the construction team.

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Center Street, Lakepoint

This road had a deteriorated asphalt surface that was to be stabilized and repaved. Early in 2002, Tooele county crews gave Center Street an overlay of recycled asphalt product (RAP) taken from milling on State Highway 30. Within a short time, the RAP had begun to ravel and the surface to degrade and Center street was selected for rehabilitation using full depth stabilization technology. In June of 2002, Tooele Public Works Department began base material rehabilitation in preparation for the new paved asphalt surface. A small milling/recycling unit (Asphalt Zipper) was used. It was connected by hose to a water truck carrying a mix of TeraZyme soil stabilizer and sufficient water to bring the RAP and underlying base materials to near OMC for compaction. By cutting to a target depth of from 9-12 inches, the RAP materials were milled and mixed with the underlying granular base and a moderate quantity of plastic fines. A few areas where the depth of the granular base exceeded 12 inches did not show appreciable fines in the mix. The one-step cutting/mixing operation allowed immediate treatment and compaction of the milled RAP and base materials that resulted in minimal moisture loss to evaporation in the treated layer. This also helped with the problem of the bed drying excessively before compaction. Some moisture variations occurred where milling passes overlapped as well as during the initial training passes due to uneven equipment speed, or because of failure to cut water flow when equipment was stopped. Remedial spot compaction the day after the milling/application operation helped to resolve the initial moisture regulation concerns and achieves adequate compaction. About 3 weeks later, on July 9th of 2002, DCP values were taken which indicated that stabilization was progressing. CBR values ranged from 14% at the unstabilized edge to a high of 48.5% in the traffic lanes. The overall average CBR had reached 32%. See Apprendix E, table and diagrams 1, 2, 3 for CBR data displays. Longer-term data were schedule to be taken before the road was to be paved directly on the rehabilitated base materials. The paving contractor prevented this plan from being carried out on the road section. In October of 2002, Willie Jaramillo, Road Department Quality Control, reported the following series of events taken by the paving contractor. ‘In October the stabilized section of Center Street-Lake Point road was scheduled to be paved. The paving company, hhhh, expressed concerns that country crews had not given the stabilized road surface sufficient camber or cross slope. To ensure acceptance of the finished surface, they attempted to grade the road to loosen soil and change the cross slope. This attempt failed because the stabilized surface was too hard to allow blading. A subsequent attempt was made to to scarify the stabilized surface layer. This effort resulted in “large plates of soil, 6 to 8 inches thick” being lifted up and was abandoned. Finally, a reclaimer was brought in to mill the stabilized material so that the new slope could be established and the material recompacted.’ This was a mistake by the paving company, did not allow the stabilized road was to be paved as planned. However, the effort clearly showed to observers the surface hardening results of stabilization of the Center Street Road. Similar experiences as this have occurred in other countries.

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Old Lincoln Highway

A layer of RAP placed on the existing gravel surface in 1997 had degraded severely over the years, with over 50% of the surface showing potholes and base-layer gravel. On July 2, 2002, stabilization and reconditioning of existing base materials and overlaying RAP were begun on 2.5 miles of the Old Lincoln Highway starting from SR 138 and continuing southeast to the boundary of Grantsville. The milling/mixing depth was adjusted to about 8 inches to avoid contact with quartzite cobbles present under the degraded RAP and base layers. By limiting milling depth, damage to the milling machine was avoided, but this prevented the incorporation of significant plastic fines available deeper in the structure of the road. This limitation caused the final gradation to appear skewed towards the more sandy gravel materials present nearer the surface. Reconditioning progressed at a rate of about 1,500 lineal feet per day on a road width of 22-24 feet. Five gallons of TerraZyme liquid organic stabilizer were applied for each 1,500-foot section along with water to approach OMC. DCP testing on the 9th of July showed an overall average CBR of 43%. See Appendix F, table and diagrams 1, 2, 3 for CBR data displays. On July 31, 2002 the reconditioned base material was given a double chip seal.

Pony Express Road

A 528-yard section of the Pony Express Road was stabilized beginning on September 1, 2002. The section is located by traveling south from Tooele on SR 36, turning right (west) onto the Pony Express road just past 199 and continuing to the “Y” that splits towards Vernon and the Dougway overlook. The section that received treatment was a steep grade, estimated at 30, that contained two sharp curves, beginning at the “Y” and continuing to the top of the overlook hill. The road was 28 feet wide and treated to a depth of about 3 inches using a grader blade and scarifying teeth. Two gallons of TerraZyme 11X were mixed into a 4,000-gallon water truck and about 3,000 gallons of the mix was applied to the prepared gravel road surface, mixed with the grader and then compacted with a nine-tire rubber-tired roller. Weather was warm and the surface received a light wetting from rain just following compaction. DCP testing on the 18th of October 2002 showed an average center CBR of 263%. See Appendix G for table and profile of CBR values across the road section. This road was to remain unsurfaced after stabilization. On December 13, 2002 Tony Perry commented that the road has received rain and snow and that it looks “pretty good”. Additional observations will be made after the spring thaw.

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Monitoring Reduction in Maintenance Cost

The county will now be able to monitor the treated roads and compare maintenance costs with untreated roads. A percent reduction in maintenance can then be estimated. Furthermore, dust levels will have greatly reduced and driving safety and comfort improved greatly.

A higher quality road surface was achieved through the TerraZyme stabilization program. The reduction in maintenance will free up equipment for use on other roads. Actual maintenance cost savings will be calculated as the road stabilization is expanded to more kilometers.

6. ACKNOWLEDGEMENTS

We thank the engineers and road teams of Tooele County for all the information on the soils, field evaluations and for the given photos, without what we could not have turned this work informative and pleasant for the reader.

Nature Plus, Inc, an ISO 9002 Certified Company, manufactures TerraZyme Soil Stabilizer. For more information: www.TerraZyme.com

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LOOSE GRAVEL RUT DEPRESSIONS – 20 cm

APPENDIX A. EXISTING, UNSTABILIZED TOOELE COUNTY ROAD CONDITIONS

APPENDIX B. STANDARD TERRAZYME APPLICATION PHOTOGRAPHS

Removal of loose gravel Scarifying of road surface

Spreading of loosened soil

Application of TerraZyme Uniform mixing Compaction

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APPENDIX C. VIEWS OF TERRAZYME STABILIZED TOOELE COUNTY ROAD AFTER 6 WEEKS

Only lower section treated – note ribbing of untreated above.

Close up of stabilized surface

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FIGURE 1

APPENDIX D. ROAD STRENGTH RESULTS – CBR%

FIGURE 1

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FIGURE 1

APPENDIX D. ROAD STRENGTH RESULTS – CBR%

FIGURE 2

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100120140160

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Average CBR % for all Stations

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FIGURE 3

0.010.020.030.040.050.060.070.080.0

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Avg. CBR - Compacted below OMC

Treatment Date Stake LE LC C RC RE AVG CTR AVG EdgeJune 2001 1 22.0 94.1 70.1 127.2 60.5 97.1 41.3

Summer 2002 2 14.4 58.3 52.8 36.2 12.9 49.1 13.6Summer 2002 3 17.7 68.4 45.6 37.1 21.4 50.4 19.5Summer 2002 4 46.9 44.4 86.0 97.6 31.4 76.0 39.2Summer 2002 5 33.5 82.2 110.3 94.2 55.2 95.6 44.4Summer 2002 6 19.9 51.7 38.1 37.3 28.7 42.4 24.3Summer 2002 7 42.9 149.5 88.3 91.8 21.1 109.8 32.0Summer 2002 8 53.1 300.3 322.4 87.2 21.9 236.6 37.5Summer 2002 9 30.0 301.8 246.6 360.7 32.2 303.1 31.1Summer 2002 10 49.8 194.4 319.4 449.2 42.7 321.0 46.3

Average Base CBR 33.0 134.5 137.9 141.9 32.8 138.1 32.9Average Sub-base CBR 31.7 21.6 27.2 27.5 25.5 25.4 28.6

Average CBR - Initial Trial 1 22.0 94.1 70.1 127.2 60.5 97.1Average CBR - Too Dry 2-6 26.5 61.0 66.5 60.5 29.9 62.7

Average CBR - Near OMC 7-10 44.0 236.5 244.2 247.2 29.5 242.6

Tooele County, Benmore Road - CBR % for Stakes 1-10

APPENDIX E.

Section Avg. CBR%Average CBR 1 38.2 27.6 41.2 48.5 14.4 34.0Average CBR 2 14.4 42.8 48.2 21.7 20.8 29.5Average CBR 3 22.8 29.7 38.4 42.8 42.1 26.8 33.8

Average CBR ALL 25.1 33.3 42.6 37.7 25.8 26.8 31.9

Figure 1 - Center Street Lake Point (Data from 7-9-02)

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Average CBR = 34.0%

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Average CBR = 29.5%0.0

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Average CBR = 33.8%

APPENDIX F.

Section Avg. CBR%Average CBR 1 27.1 65.8 40.0 96.5 46.4 55.2Average CBR 2 21.1 32.4 40.0 66.9 33.8 38.8Average CBR 3 22.8 29.7 38.4 42.8 42.1 26.8 33.8

Average CBR ALL 23.7 42.6 39.5 68.7 40.8 43.0

Old Lincoln Highway (Data from 7-9-02)

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Average CBR = 55.2

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Average CBR = 38.8

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APPENDIX H.

TerraZyme is a fermented-enzyme product, a chemical, organic, and liquid concentrated substance, used with increasing frequency to improve the stability of aggregates and soil materials in the roadways and other pavement structures. In other parts of the world, these materials are providing great economic benefits. In Utah, they are only now being used for rural and secondary road projects in private sectors, but they have applications in municipal and state projects. It is foreseen that in the near future, in order to not become static and inattentive to progress seen elsewhere, the counties of Utah and the State Department of Highways and Roads will begin to establish standards through research and extensive observations in field, for these proprietary soil products.

This concentrated stabilizer liquid are specifically formulated to modify the engineering properties of soils and aggregates; it requires dilution in water before the application to allow for the product to be dispersed and uniformly mixed with the particles of soil material being treated. The dosage levels of the stabilizer concentrates vary from .75 gallons up 1.25 gallons for 165 yd3 of soil, depending on the soil type and soil characteristics. The amount of dilution water depends on soil dryness. In the field, measurements are made to determine the difference between the actual field soil moisture content % and the optimum moisture content % for maximum compaction. This calculated amount of water brings soil up to optimum moisture content. In cases where the soil material contains high amounts of fines or high plasticity, the water added is often from 1 to 2% below optimum moisture.

In countries that are using organic-enzyme stabilizers, in general the usage costs are much lower than conventional chemical stabilizers. This is because there initial price is lower, the application is simpler and less expensive and transport is cheaper. In these countries economic factors continue to open new application areas. Even when modest increments in the road stability occur, there is an increase cost-effectiveness and improvement in performance and durability of the roadways. Government studies in the country of Malaysia have documented results showing over 75% reduction in maintenance over a three-year period on TerraZyme treated secondary roads.

The verification that TerraZyme soil stabilizer can provide significant improvements in the properties of the treated materials is a requirement for road engineers and researchers, who have not had previous field observation, experience and analysis of this technology.