Project planning and design is a complex task, often demanding a strategic blend of professional judgement, cost considerations, risk, and sustainability. In response to these challenges, Presto Geosystems developed the Presto Geo P³ Project Planning Portal, a free, web-based suite of geotechnical calculation tools. Designed with engineers, contractors, landscape architects, and project owners in mind, Presto Geo P³ streamlines your project planning process, allowing you to quickly perform calculations to evaluate a wide range of possible technical solutions for your project.

Presto Geo P³ Unique Features & Benefits

With its pioneering support for geocells—a first in the industry—and integration of calculations for aggregate and vegetated porous pavements and site access, the Presto Geo P³ portal sets a new standard in value engineering evaluations.

Key offerings of the Presto Geo P³ include:

• Geotechnical Calculations:
  • Soil Stabilization: Unpaved, Flexible Pavements, and Rigid Pavements
  • Porous Pavements: Vegetated and Aggregate Surfaces (Rigid and Flexible)
  • Site Access: Access Roads
• Personalized Dashboard: Users can efficiently organize their projects and associated calculations for easy access and review.
• Customizable Output: Detailed calculation output with customizable fields for your project/firm/client name, a summary of input parameters and calculation results, and a cross-sectional graphics illustrating user-selected layer thicknesses and material types.

Resource Library

Presto Geo P³ also serves as a comprehensive resource hub. With access to a vast library of technical documents and product resources, you can deepen your industry knowledge, stay up-to-date with the latest product advancements, and make more informed decisions when it comes to your projects.

Designed to revolutionize project planning and execution, Presto Geo P³ empowers you to build smarter, faster, and more sustainably. Start planning your next project today.

Written By: Cory Schneider, Environmental Scientist, Presto Geosystems

Natural resources are finite, or at a minimum, can easily be consumed faster than they can be replaced. As such, the conservation of natural resources is a pragmatic endeavor. Geosynthetics—widely available materials used in construction, civil engineering, and environmental protection—can be useful in promoting the conservation of these resources. When used as intended, geosynthetics can enhance soil properties and reduce the demands placed on natural resources.

Types of Geosynthetics

Geosynthetics are typically made from synthetic polymers, such as polyethylene, polypropylene, and/or polyester, and are designed to be durable and resistant to weathering and other environmental factors.

General groupings of geosynthetics include:

• geotextiles,
• geogrids,
• geomembranes,
• geocells,
• erosion control blankets (ECBs),
• and turf reinforcement mats (TRMs).

Geotextiles (permeable) and geomembranes (impermeable) provide separation, while geogrids and geocells provide varying degrees of stabilization and confinement. ECBs and TRMs, made with a combination of natural and synthetic fibers, resist surficial erosion by preventing seed washout prior to germination.

Application areas where these geosynthetic materials are used typically include:

• load support,
• slope, shoreline, and channel protection,
• and earth retention.

Using Geosynthetics in Load Support Applications to Conserve Natural Resources

In load support applications, geogrids, geotextiles, and geocells can all be used to reduce structural cross-section depths, thereby conserving natural resources. The figure below illustrates this benefit and provides a comparison of four structurally equivalent unpaved road sections over a very weak subgrade with a CBR of 0.5%.

As shown, the conventional cross-section in this case would require more than 36 inches of aggregate to achieve minimal stability, while the planar geosynthetic option (geogrid + geotextile) would require 26 inches of aggregate. Most notably in this case is that geocells—specifically the GEOWEB® Geocells—can be used to achieve an optimal section thickness of only 15 inches, and where suitable on-site material (OSM) is available, it is possible to limit imported aggregate to just the wearing course.

How Geocells Conserve Natural Resources

Through full-depth confinement, geocells allow for the use of lower-quality, non-cohesive soils and recycled materials (concrete, asphalt), further conserving resources through beneficial reuse. Beneficial reuse of any of the aforementioned reduces imported material requirements, thereby conserving aggregate, and with the additional benefit of less truck traffic to the site, conserves oil and gas and puts less stress on local roadways. Properly designed geosynthetics can also increase your roadway´s useful life and reduce or eliminate maintenance needs.

In slope, shoreline, and channel applications, ECBs, TRMs—and to a further extent—geocells, help prevent surficial soil erosion—a process that can cause significant damage to natural ecosystems and lead to the loss of valuable topsoil. While ECBs and TRMs are suitable to protect the surface, adding geocells to the cross-section can prevent supersaturated soils below these products from washing downslope or downstream, and can improve the hydraulic performance of the materials used in the geocells.

Finally, geosynthetics can be used in constructing retaining walls and embankments, which can help conserve resources by reducing the need for land excavation and fill. In retaining wall construction, geogrids—and occasionally geotextiles—are used as tiebacks in Mechanically Stabilized Earth (MSE) structures, while geocells and TRM wraps are just a few of the many different geosynthetic facing options available. Geocells can not only be used to create living green walls to help stormwater infiltrate naturally and add an aesthetically pleasing finish to a structurally sound engineering solution, but research has also shown that geocells can withstand high levels of seismic shaking and may be a suitable option in many earthquake-prone parts of the world.

Let Our Engineers Run Design Calculations on Your Next Geocell Project.

See the Cost and Material Savings for Yourself!

Presto Geosystems’ engineering team works closely with you to provide free project evaluations, with engineering support from the preliminary stages through construction. The project evaluation will deliver a technically sound, cost-effective solution based on four decades of accredited research and project experience.

Contact our knowledgeable staff and network of qualified distributors to discuss your project needs today and see how we can help you save money while conserving natural resources. Responsible use of engineered materials designed for long-term performance in the environment can help you achieve a more sustainable approach to construction.

Use our free online tools to keep your projects moving forward.

Written By: Michael J. Dickey, P.E., Samantha Justice, P.E., Bryan Wedin, P.E.

When constructing roadways over soft soils and weak subgrades, geocells are one of the most powerful value engineering tools available to the civil engineering and construction industries today. Understandably, some engineers may be apprehensive about using a geosynthetic product for which they have an incomplete technical understanding. So, if you’ve ever wondered how geocells work in load support applications – and the relationship between lateral confinement and hoop stress – you’ve come to the right place.

Generally speaking, geocells can be used to alter the geometry of a soil pressure bulb beneath an applied load through a phenomenon known as the mattress effect. Key to the mattress effect is a physical mechanism unique to geocells known as lateral confinement. When a load is applied to a geocell-reinforced layer, lateral earth pressures develop within the infill material, which is confined laterally by the cell walls against movement, in turn developing upward shear resistance along wall interfaces throughout the interconnected network of cells. In essence, lateral confinement converts horizontal earth pressures into upward resisting shear forces.

When combined with suitable base reinforcement (i.e., an enhanced woven geotextile), it becomes possible to construct over very weak subgrade materials, including those with standard penetration resistance (SPT-N) values less than 2 blows per foot (CBR < 0.5%), where most planar geosynthetic products, such as geogrids, would otherwise fail.

Now, where does hoop stress come into play, and how does it relate to lateral confinement?

Hoop stresses develop within the cell walls as earth pressures propagate radially in response to an applied load at ground surface. In other words, the same earth pressures responsible for developing interface friction between the geocell and the infill material also result in hoop stresses within the cell walls. Although not perfectly cylindrical, geocells can be envisioned to behave similarly to an interconnected network of pressurized cylinders, wherein hoop stresses are a function of the net pressure that develops due to the internal and external pressures acting within and around each cell.

In this manner, radial pressures that develop within each cell are resisted by those that develop in the adjacent cells, and hoop stresses may be estimated using the classic equation for hoop stress for a pressurized thin-wall cylindrical vessel:

σ_H = p_net*(D/2t)

Where,

σ_H = hoop stress

p_net = net pressure = p_i – p_e

p_i = internal pressure

p_e = external pressure

D = geocell diameter

t = wall thickness

The internal active earth pressure in a cell directly beneath a point load can be calculated using Boussinesq’s point load stress equation. Concerning external, or “passive”, earth pressures in adjacent cells, Emersleben (2009) investigated the interaction between hoop stresses and passive earth resistance in geocell systems and observed that lateral pressures in adjacent cells decrease exponentially with increasing distance from the actively loaded, or “source” cell(s) – in effect, defining a pressure gradient. Based on Emersleben’s findings, it is possible to evaluate the net earth pressure that develops between the interior and the exterior of a cell wall, using the thickness of the cell wall as the distance between two points along the defined pressure gradient line.

Not surprisingly, the largest net earth pressures, and largest hoop stresses, occur in cells directly beneath the perimeter of the load footprint, the wheel contact area in the case of vehicle loads. Based on this, it is possible to estimate the maximum hoop stresses that would be expected to develop in geocells in response to standard AASHTO load conditions.

Accordingly, the table below summarizes the estimated hoop stresses that would be expected to develop under standard AASHTO load conditions in a 6-inch geocell-reinforced layer overlain by 2 inches of aggregate wearing course. The calculations assume a 9.5-inch diameter geocell infilled with coarse sand having an internal friction angle of 32 degrees.

As shown, the corresponding tensile forces that develop under working load conditions are relatively modest due to the lateral confinement effect of the adjacent cells. When compared to the typical yield strength for most high-quality HDPE geocells, the above-referenced tensile forces are well within the elastic region for the material, and would not be expected to undergo any permanent deformation or “creep” over time, even when subject to repeat traffic loads over many years.

With regard to strain, the elastic response of the geocell-reinforced layer will ultimately be governed by the elastic properties of the infill material and provided that suitable granular infill is used, the development of any significant strain in the cell walls will be heavily constrained by the effects of lateral confinement. Because of this, the actual strain that develops in the cell wall will be far less than the amount of strain represented on a typical stress-strain curve generated from laboratory tests such as ISO 10319 or ASTM D4595 where samples are subjected to tensile forces in an unconfined state.

This is not to say that hoop stress is not important. Development of hoop stress is essential for the proper engagement of the lateral confinement mechanism. Moreover, the ability to estimate hoop stresses under specific project circumstances can be useful as it allows designers to develop a preliminary (and very conservative) understanding that tensile forces in the cell wall will remain within the elastic region for the material (with the caveat that many laboratory test methods such as ISO 10319 ignore the effects of confinement, and therefore tend to overestimate strain levels).

In terms of long-term hoop integrity as it pertains to the cell wall (junctions are another matter altogether), dynamic mechanical analysis using a method such as ISO 6721 allows for more accurate characterization of expected material behavior under repeat dynamic loads at reduced strain levels. In general, provided the product is a high-quality HDPE geocell with a flexural storage modulus of at least 116 ksi (800 Mpa) and a 100-year durability rating (ISO 13438), the product can be expected to perform as intended throughout the life of the project.

References:

Emersleben A. et al (2009). Interaction Between Hoop Stresses and Passive Earth Resistance in Single and Multiple Geocell Structures. GIGSA GeoAfrica 2009 Conference, Cape Town 2 – 5 September 2009.

When extreme weather events occur, communities are often left to grapple with the devastating effects. An increase in extreme weather patterns, coupled with aging or inadequate infrastructure, amplifies the often dangerous and costly damage that ensues—especially for vulnerable communities living in low-lying areas.

According to a recent study, the United States could see a 26.4% increase in flood risk by 2050, which could cause significant damage to existing infrastructure. For this reason, it is vital to build resilience into infrastructure projects to mitigate climate risk and ensure the long-term reliability of critical infrastructure.

Incorporating geosynthetics into infrastructure can improve the ability of communities to withstand and recover from extreme weather events. For example, in hurricane-prone parts of the country, designing robust access roads along power transmission lines allows repair crews to safely and quickly restore power to communities that might otherwise be without electricity for days or even weeks. Geosynthetic products, such as geocells, can be used to construct reliable access roads along transmission infrastructure, which often traverse very remote areas with difficult terrain and very soft ground conditions. Through an interconnected honeycomb-like network, geocells confine and stabilize soils that would otherwise be unstable under loading.

When used in load support, slope stabilization, channel protection, and retaining wall applications, geocells are a powerful weapon against the long-term effects of climate change. This article discusses several examples where GEOWEB® geocells were successfully used to help communities adapt to, and recover from, extreme weather events.

GEOWEB Porous Pavements Used for Rebuilding Roads, Replacing Transmission Lines Damaged During Hurricane Michael in Florida’s Panhandle

Hurricane Michael caused extensive damage to Florida’s power grid network, leveling more than 100 transmission towers in a 34-mile right-of-way from Port St. Joe to Callaway. This right-of-way crosses swampy, remote, and hard-to-reach areas, making rebuilding the grid even more challenging. This extremely wet, muddy ground prevented repair vehicles from accessing the area. Helicopters were employed to transport the new steel towers installed on-site.

Accessing the lines for maintenance would require a stronger roadway to support heavy vehicles in the wettest areas. The GEOWEB Load Support System was used to make the roads operational and improve performance in saturated conditions.

The GEOWEB system was placed over an enhanced geotextile and filled with crushed aggregate to create access roads across critical wetlands and stabilize pole pads. The access roads and pads are permanent.

GEOWEB Geocells Repair Storm-Ravaged Trail & Maintenance Road

In the spring of 2018, several storms violently swept through areas along southern Maine’s coastline, devastating the beaches and trails of Fort Foster—a town-owned park in Maine. Known as “nor’easters,” these destructive storms form along the east coast, bringing strong winds, rain, and flooding to the New England states. As the storms rolled past, the damage was visible to Fort Foster and Kittery Point’s 2.1-mile-long shoreline walking trail and maintenance road, as well as on the slopes leading down to the beach.

The park’s goal was to repair the damage and protect the slopes, maintenance road, and recreational trail from future storm damage. The GEOWEB® Soil Stabilization System was chosen to restore and protect two sections of the park’s shorelines and trails.

By using the GEOWEB System, the park was able to armor the maintenance road, recreational trail, and slopes from future storm events. Since being installed in 2018, the GEOWEB Load Support and Shoreline Protection Systems continue to perform as designed, allowing the community to once again enjoy the trail system and local beaches.

GEOWEB Hard-Armored Shoreline Protection System Protects Vulnerable Riverbank from Erosive Forces

The extreme El Niño event caused the western Pacific to warm, developing atmospheric convection and increased rainfall. The storm events caused catastrophic flooding and severe erosion in the eastern equatorial region of Ecuador and Northern Peru. A portion of the Zarumilla River, located in the remote Tumbes region in Northwestern Peru, was experiencing severe erosion and required a shoreline protection solution to prevent further deterioration of the riverbank.

The GEOWEB® Shoreline Protection System was selected to protect the Zarumilla riverbank against future storm events. The GEOWEB system with concrete infill provides economical, hard-armored protection of slopes and channels exposed to high flow velocities and high shear stresses. The system has been proven to withstand sustained flow velocities over 36 ft/s (11 m/s) and shear stresses of 20.9 psf (1.0 kPa), outperforming rip-rap, gabions, and other conventional hard armor strategies.

The product was shipped to the site in September 2020, and installation was complete by December 2020. The project was completed on schedule and within budget. The GEOWEB® Shoreline Protection System is performing to expectations and will provide much-needed protection to the Zarumilla River and the communities that depend on it when the next major storm hits.

GEOWEB Geocells Used for Erosion Protection of Canal Floodwall

Erosion of the 17th Street Canal’s flood protection system was a major concern for the Southwest Louisiana Flood Protection Authority-East. The Authority required a solution to protect the canal’s slope against erosive forces and prevent a floodwall breach in the event of a tropical storm event.

To mitigate channel slope erosion, engineers chose the GEOWEB® Confinement System to stabilize the slopes along the Metairie side of the drainage channel. By confining the infill material, the GEOWEB system prevents flow from causing scour and erosion on slope surfaces.

The construction company installed approximately 380,000 square feet of GW40 (mid-cell size, six-inch deep panels) over a woven geotextile along the canal’s slope and infilled the cells with crushed aggregate sized based on research and testing at Colorado State University hydraulics lab.

The GEOWEB System:

• Allows the use of smaller, less expensive rock—even waste rock which decreases installation and transportation costs.
• Creates a permeable, cover when drainage is desired but vegetation cannot be established.
• Resists high velocities and tractive forces.

Design Support & Resources for the GEOWEB System Applications

The engineering team at Presto Geosystems works closely with engineers and project planners, offering free project evaluation services and on-site support. Our recommendations will deliver a technically sound, cost-effective solution based on four decades of accredited research and testing data.

Please contact our knowledgeable staff and network of qualified distributors and representatives to discuss your project needs today.

How long have you been with Presto Geosystems?

Time flies when you are having fun! I have been with Presto Geosystems going on 14 years. In that time, I got to work with some really great people and enjoyed speaking with Gary Bach on how geocells were invented back in the late 70s and early 80s.

Can you tell us a bit about your background?

I grew up in the Upper Peninsula of Michigan and enjoyed doing all things outdoors. My father was an Olympic ski jumper, so I had no choice but to strap on a pair of skis and follow in his footsteps. I became pretty good and was in three junior Olympics before a bad fall ended that part of my life. I grew up before video games, so we were always outside playing football, baseball or just riding bikes.

After a year at Michigan State University, I attended college at Michigan Tech University in Houghton, MI and graduated with a degree in Environmental Engineering. After graduation, I moved to Green Bay, WI, and worked for Foth & Van Dyke and then Robert E. Lee engineering consulting firms before joining Presto Geosystems.

What attracted you to the world of engineering and geosynthetics?

I was lucky enough to land a wonderful job out of college at Foth & Van Dyke in Green Bay, WI. Foth was a growing consulting firm at the time and the staff was always at the leading edge of technologies. When I started in consulting, geosynthetics were just becoming an option for roadway and earth retention projects. I got to see early on how engineers included geosynthetics in their projects and how the approval agencies accepted them. I guess I’m really showing my age…

What does your job entail? Can you take us through a day in the life as the Chief?

The best part of my job is that every day is different and it seems there are no “typical” days. Our products can solve so many soil stabilization problems that I am blessed to work with engineers all over the world on their challenging projects. It is rewarding to walk away from my computer at the end of the day knowing that the Geosystems Team and our worldwide distribution network work together to make a difference.

What do you like most about your job and/or what do you like most about this industry?

The people and relationship building through the years has been enjoyable. Our industry really works closely to ensure successful geosynthetic projects. I enjoy working on the AREMA, ASTM, and ISO committees and the discussions with the industry experts.

What is the most challenging part of your job?

How do you turn it off? When I first started consulting 35 years ago, we didn’t have the technology we have today. We didn’t even have AutoCAD or personal computers at the time! Everything was done by hand, and I think we understood the calculations better. When you left work, it allowed you to unwind. Today, it seem it is 24/7, especially with the advancements in technology. It can be a challenge to turn it off.

What do you enjoy doing when you aren’t out helping solve the world’s soil stabilization and erosion challenges?

My wife and I stay pretty active, especially in the summers. We live on a golf course, and you will always find us out playing or enjoying a cocktail on the 19^th hole! Family is a big part of our life. We are lucky to have four wonderful kids who have moved out of the house and are employed! They have given us three beautiful grandchildren (one more on the way in December) that we love to spend time with and spoil which is what grandparents are supposed to do.

What is your favorite place in the world to visit?

I have been lucky to have traveled all over the world for leisure and work. A few of my favorites include Austria, Switzerland, Australia, and Banff in Canada. If had to pick one it would have to be Punta Cana since my wife and I have the best of times when we visit. We have so many great memories there. We both have stressful jobs, so it is nice to get away, relax on the beach, enjoy some cocktails and let someone else do the cooking.

If you could meet anyone, living or dead, who would you meet?

This is an easy one but hard to decide which person. I am a huge old western movie fan. It is to the point that if I am watching tv and scrolling through the channels and come across one, my wife just gets up and goes to another tv. I would have to pick my top 20, throw them in a hat, and just pick one and would be fine.

What would you name the autobiography of your life?

Never a Dull Moment.