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Protecting Environmental Geomembrane Covers With Suspended GEOWEB Geocells

Posted by Katie Bocskor

Economic pressure, the desire for green solutions, and the intensification of climate extremes have converged to create a need for better methods to effect soil stabilization. Fortunately, a proven technology exists that addresses issues associated with these conditions and provides a more stable cover solution for landfill covers, lagoons, stormwater containment basins, and other geomembrane-covered systems. Soil, aggregate, and concrete protective covers over geomembranes can be secured against known gravitational, hydrodynamic, and seismic forces using the GEOWEB® Soil Confinement System.

Soil and aggregate are commonly used as a protective cover over liners on slopes of 3H:1V or less. However, when slope gradients are greater, unconfined soil and aggregate covers are typically unstable and not used. In arid areas, cover depth may range from 75 mm (3 in) to 150 mm (6 in). Where conditions support vegetation, cover depth may range from 100 (4) to 600 mm (24 in) or greater where the final depth is a function of the characteristics of the desired vegetation. Regardless of cover depth, if an extreme rainfall event occurs that is 10%, or greater than what would typically be expected, soil mass increases, assumed friction angles decrease, and factors of safety for soil stability drop to a point where failure of the cover occurs and exposure of and/or damage to the geomembrane results.

Suspended GEOWEB Solution
The use of the GEOWEB 3D slope cover system best addresses critical details when designing or remediating geomembrane covers. With the aging infrastructure of dams, impoundments, and landfills, design engineers are looking for innovative and cost-effective solutions to build and repair new and existing facilities. The adaptability of the 3D system provides geomembrane protection while contributing to an easier and faster installation process.

Structural Support System
Because traditional stake anchoring would puncture the geomembrane, the GEOWEB system is suspended from the crest of the slope through an integrated structure of tendons and load transfer clips. This structural support system directly protects the geomembrane from accidental puncturing and natural degradation–which indirectly prevents soil contamination and erosion. The structural support also allows the GEOWEB system to work on slopes that are much greater than 3H:1V.

A variety of infills may be used, tailored to a project’s specific needs. When lining a landfill cover, crushed aggregate or vegetated infills are common because they put less pressure on the geomembrane cover and allow for growth of the landfill if necessary. For more structural projects, such as dam linings, concrete infill may be the better choice and may allow a thinner concrete cross-section for a reduced cost. This demonstrates another unique aspect of the geocell system, in that the 3D structure of the geocell can act as the formwork for a concrete pour, eliminating the need for expensive and timely construction techniques. Full design evaluations should be performed in order to analyze the loading, shear forces, and factors of safety on each project.

 

Read Technical Paper >>

Original paper entitled, “Failure of a Landfill Cover and Remediation using Geocells” was presented at the First Pan American Geosynthetics Conference & Exhibition, March 2008, Cancun, Mexico. Original paper was co-authored by Mauricio Abramento, PhD, CEG Engenharia, Marcos Mello Rocha Campos, MSc, GEOKLOCK Consulting and Environmental Engineering, Claudia Vasquez Bastias, Fiberweb Bidim and Daniel Senf, PE, CPESC, Presto Geosystems.

GEOBLOCK Grass Pavers: Fire Lane Access System

Posted by Katie Bocskor

GEOBLOCK® POROUS PAVEMENT SYSTEM

Environmental regulations that control and limit stormwater runoff, reduce impervious surfaces, and increase green space have resulted in the growth of permeable pavements for traffic areas. The GEOBLOCK Porous Pavement System offers support for all vehicular loadings and protects the grass from the  damaging effects of traffic while allowing natural groundwater replenishment.

Examples of the GEOBLOCK system providing solutions for fire access lane requirements are illustrated in this case study summaries below.

Test 1: The City of Kentwood (1994)

Kentwood, Michigan

GEOBLOCK System Put to the Test

The City of Kentwood, Michigan put the GEOBLOCK system through a worst-case scenario field test to measure performance and prove the system’s capabilities.

Prior to testing, a series of less-than-ideal installation conditions were established:

  • Five inches of sand subbase was installed, developing a base support capacity of only 2.8% CBR.
  • GEOBLOCK units were laid parallel (rather than perpendicular) to the direction of traffic.
  • Edge restraints, typically used to help prevent block shifting until vegetation, were omitted—both of which help anchor the system.
  • The test area was not proof-rolled prior to load applications.

The fire marshal directed a 60,000 lb (22,400 kg) ladder/pumper to drive onto the unfilled 13 ft x 48 ft (3.9 m x 14.6 m) GEOBLOCK test pad, drop its outriggers and begin tests while geotechnical engineers monitored the systems performance.

After a series of rigorous tests, the ladder/pumper stayed on the GEOBLOCK pavement for a full hour.

The Results:

Under loading, inspection revealed only a 1/2 in (13 mm) deflection in the pavement system. After removal of the load, the GEOBLOCK pavement rebounded to its original condition in less than one hour, and the units were recovered for future use. As a result of this test and the system’s performance, the City of Kentwood approved the GEOBLOCK Grass Pavement System for use on its fire access lanes.

Case Study 1: Microsoft Campus (1996)

Redmond, Washington

The Challenge

As Microsoft Corporation’s facilities expanded through the years, so did their need for fire access lanes at their campus buildings. Grassed access lanes rather than hard-surface paving were desired to enhance the aesthetics of the new building and grounds. The search for a reliable porous pavement system led them to the GEOBLOCK Grass Pavers.

The Solutions

At their Washington State Campus, 8,600 square feet of the GEOBLOCK system was installed for permeable, grass fire access lanes around nine campus buildings.

Previously, 9,000-square-foot installations were installed around three other campus buildings. At other locations, existing fire access lanes were expanded using the GEOBLOCK system to meet new code requirements.

The Results

Implementation of the GEOBLOCK system helps preserve the campus’ natural look while providing the load support necessary to accommodate all emergency vehicles.

Test 2: AT&T Corporate Center (1994)

Basking Ridge, New Jersey

A worst-case scenario field test was also required by the Lyons Township Fire Department, New Jersey prior to approving the GEOBLOCK System for a fire access lane at the new AT&T corporate convention facility.

A test pad was installed in front of the facility adjacent to a concrete block entrance drive. Side restraints, sometimes used to anchor the pavement system, were purposely omitted. A few weeks later with only light grass established, the Lyons Township Fire Department was ready to begin the testing.

Under full pressure, firemen turned the hose directly on the GEOBLOCK platform and proceeded to saturate the test pad. With water still standing on the pad, an 80,000 lb. fire engine was backed over the saturated area, and with the outriggers lowered, was lifted off its tires. A series of tests were performed under full load and less-than-ideal conditions to determine the capabilities of the GEOBLOCK system.

The Results

After passing the tests successfully, the Fire Department approved the GEOBLOCK system at the AT&T Corporate Center for fire access use.

Case Study 2: Friends University (1999)

Wichita, Kansas

The Challenge

When officials at Friends University planned to beautify the exterior of the campus’ newly renovated Davis Hall, it included removing the large driveway leading up to the building’s main entrance. The university wanted to create a large open area, or pedestrian mall, where campus events could be held in front of the 110-year-old Davis Hall. The new design included a 76-ft diameter paving stone mosaic at the Rose Window Plaza in front of the hall to replicate the pattern of the stained glass window. The finished concept would include sidewalks, flowerbeds, and period lights.

Removing the frontage road and circle drive left the mall with diminished emergency vehicle access. The university sought an alternative to hard surface paving that would blend naturally with the green look of the campus while providing the necessary load support for maintenance and emergency vehicles.

The Solution

The GEOBLOCK Load Support Solution was chosen to best complement the new pedestrian mall and paving stone design work. About 9,000 square feet of the GEOBLOCK system was installed with an engineered base of sand and topsoil. Topsoil and a hearty bluegrass and fescue blend sod were placed in the cells of the GEOBLOCK units.

The Results

The GEOBLOCK system met the University’s need for vehicular and pedestrian load support over grassed areas while complementing the aesthetically pleasing entrance and protecting the grass from the harmful effects of the traffic.

Case Study 3: Homestead Village Complex (1997)

Bellevue, Washington

The Challenge

Faced with the common problem of providing emergency vehicle access while maintaining desirable green space, architects and contractors building the Homestead Village Complex rejected traditional paving materials in favor of a permeable system.

The Solution

The GEOBLOCK System was utilized in three areas at the apartment complex—two fire access lanes and one access road to the complex’s water detention pond. Three areas totaling 3,000 square feet were installed in less than three days, starting from site preparation through seeding.

The Results

After the system was fully vegetated, tests were performed by the local fire department, and the GEOBLOCK system was approved for use.

Case Study 4: Intervet, Inc. (2002)

Desoto, Kansas

The Challenge

The mall area in front of the pharmaceutical company’s office building was designed with a series of intersecting concrete roadways for emergency access. The owner desired green space for visual appeal in the large adjacent areas. However, a typical turf-only surface would not reliably support the load of fire trucks and emergency vehicles.

The Solution

The GEOBLOCK system was chosen for its aesthetic appeal, ease of installation, and load support capabilities. The GEOBLOCK units were placed on a prepared base such that their tops were flush with the adjacent concrete roadways. Units were set in place, cut as needed to conform to site irregularities, infilled with topsoil, and seeded.

The Results

The landscape contractor and owner were very satisfied with the final solution. When tested under full load, less than one-half inch of deflection was noted in the loaded areas.

GEOWEB Geocells Combined with a Turf Reinforcement Mat (TRM)

Posted by Katie Bocskor

GEOWEB® System – Research Synopsis

Research Objective
Measure the performance of the GEOWEB (GW) material combined with a turf reinforcement mat (TRM) (integrated system) with topsoil infill and vegetation under varying shear stresses and flow rates to quantify both hydraulic forces and
corresponding soil loss.

The test consisted of a series of continuous one-hour flows over the GW-TRM system at incrementally increasing discharges. The performance threshold was defined as the point at which 0.5 inches (13 mm) of soil loss occurred.

Research Scenario

The Research Facility
Steep-Gradient Overtopping Facility (SGOF) at the Hydraulics Laboratory of the Engineering Research Center (ERCD) at Colorado State University (CSU), Ft. Collins, Colorado

Test Timeframe
April 2005-August 2006

Test Materials

  • GEOWEB Soil Stabilization System
  • North American Green C350 Turf Reinforcement Mat

Scope of Test

Hydraulic performance testing was conducted on an integrated system comprising the GW30V textured/perforated GEOWEB System and the North American Green C350 composite turf reinforcement mat. The C350 TRM was chosen for its known performance in the test apparatus. Six tests were conducted under the research program to measure the performance of the integrated system, identify stability threshold conditions, and quantify both hydraulic forces and soil loss.

Assembling the Test Components

  • The selected textured/perforated GEOWEB section was placed in the test apparatus and topsoil infill added.
  • When the GEOWEB cells were completely infilled with topsoil, the soil was lightly tamped.
  • Grass seed and mulch were added to finalize the growing medium.
  • The turf reinforcement mat was secured over the textured/perforated GEOWEB section by ground staples at defined intervals in conformance with the manufacturer’s recommendations.
  • Vegetation was established over a 14-week period to allow root system integration within the perforated cells of the GEOWEB material. Kentucky bluegrass was the chosen vegetation for this series of tests.

Test Procedures/Result

The test apparatus is lifted and positioned in place in the flume with a 2h:1v slope. In an effort to model storm conditions, the soil was saturated prior to the six tests. The integrated system was subjected to flow discharges ranging from 10 ft/sec (3.0 m/sec) to 27 ft/sec (8.2 m/sec). Two sets of water surface elevation data were taken; one at the beginning and one at the end of each hour-long flow to obtain an average depth. Vegetation density counts were also measured prior to and directly after each test at upstream, midstream, and downstream locations.

Observations

Exposed to the extreme flows, and despite ordinary topsoil infill and typical TRM staple patterns, the system showed no measurable soil loss. It was observed that the vegetation had decreased stem and blade count during the total testing timeframe, however at a decreasing rate of loss for each incremental test.

Chosen vegetation type will influence the stem and blade loss. Typically a hardier grass type or blend would be used for field applications rather than pure Kentucky bluegrass. At the completion of the test, an extracted soil sample showed vegetative root penetration to a depth of 1.5 inches (38 mm), with larger roots interacting with the cell wall perforations. As future growth occurs, root interaction will increase.

Testing Summary/Conclusions

No system instability was observed for shear stresses up to 15.9 lbf/ft2 (77.6 kgf/m2) and for average velocities up to 26.5 ft/sec (8.1 m/sec) with peak velocities over 29 ft/sec (8.8 m/sec). Due to facility constraints that prevented testing higher velocities than those reported, system failure limits were never found. The test results for the integrated system far exceed the limits of separately reported values of the GEOWEB Cellular Confinement System (CSS) and turf reinforcement mats with topsoil/vegetated soil.

Field Applicability

The results of this integrated system testing can be applied to highway drainage ditches, spillways, dam, and pond overflow systems and other vegetated channels exposed to high shear forces and intermittent, longer-duration velocities. This system replaces rip rap with a less expensive, low maintenance, aesthetically pleasing green solution.

Exclusivity of Results

The results of the testing are exclusive to the materials utilized in this test. Specifically, no inference shall be drawn from this research review indicating suitability of any cellular confinement system other than the genuine GEOWEB Cellular Confinement System. Due to the challenging nature of the projects for which this application applies, we strictly warn the reader of the potential for significant infill loss, project failure, and/or loss of property or life if substitutions are made including, but not limited to the GEOWEB Cellular Confinement product and a properly prepared engineering design analysis.

Certifiable Results

Results of this testing/research are certifiable and only available through Presto Geosystems.

Download CSU Vegetated Research Summary >>

Solar Installations on Closed Landfills: Using Geosynthetics to Overcome Redevelopment Challenges

Posted by Ashley Beyer

Written by: Michael Dickey, P.E. (WI, FL, GA, NC), Director

Redevelopment of closed landfills and capped solid waste sites represent a unique opportunity for landfill owners, solar developers, and communities to work together to put underutilized properties back into productive use. Moreover, many such sites are conveniently located near existing transmission infrastructure and may be easier and more economical from an interconnection standpoint than rural greenfield sites.

However, building over a closed landfill poses unique challenges because most landfills are covered by an engineered cap not typically designed to support loads from permanent foundations or heavy equipment. Additionally, state and federal regulations generally prohibit any activity that could potentially breach or damage the cap. Therefore, retrofitting a closed landfill for utility-scale or community solar projects requires careful planning. Ultimately, the project must not jeopardize the intent of the original cap design; that is, to protect human health and the environment.

closed landfill with vegetation

Selecting a Suitable Foundation

Concrete slabs and pre-cast ballast footings are both foundation options for solar system installations on landfill caps. In general, concrete slab foundations are heavier than ballast footings and pose a higher risk of creating landfill settlement and side-slope stability issues. Ballasted footings are a lighter-weight option and may be suitable for flat landfill surfaces; however, engineering difficulties emerge as the slope of the landfill surface increases. Ultimately, the foundation must be designed to protect the system against wind uplift and sliding without exceeding the allowable bearing capacity of the cap.

Allowable bearing capacity is very site-specific and is typically a function of cap thickness and composition, combined with appropriate considerations to account for the makeup and age of the underlying waste material. For example, old construction debris that has been previously compacted will not experience significant settlement because of low biochemical degradation; therefore, the likelihood for damage to the cap, or the solar installation, can be expected to be relatively low. Conversely, a thin cap over a relatively new landfill cell containing unconsolidated municipal waste, which would see short- and long-term settlement, may be at a much higher risk of damage, and any new construction may therefore be subject to a much lower allowable bearing capacity requirement.

There are methods to improve bearing capacity and mitigate settlement for new developments on previously closed landfills. Geosynthetics can be employed to dissipate loads from foundations and construction equipment and provide long-term protection against the damaging effects of differential settlement. Geocells, in particular, can be integrated into the leveling course beneath ballast footings, or the base layer beneath a concrete slab, to improve the allowable bearing capacity and protect solar foundations from cracking and settlement problems.

Improve Allowable Bearing Capacity, Protect Against Differential Settlement Using Geocells

Geocells—recognizable by their unique three-dimensional honeycomb-shaped appearance—are a specialized geosynthetic material widely used in construction for load support, slope/channel protection, erosion control, and mechanically stabilized earth (MSE) walls. Compared to planar geosynthetic products such as geogrids—which commonly rely on expensive imported high-quality aggregate—geocells are highly versatile and can be filled with a variety of commonly available and economical infill materials. Compatible infill materials include sand, soil, aggregate, concrete, pulverized debris, recycled asphalt, or other locally sourced materials.

geoweb loadWith geocells, it is not uncommon to see an overall reduction in the required thickness of the base layer or leveling course in a load support application by 50% or more, along with an overall improvement in allowable bearing capacity. This applies to foundations as well as permanent or temporary site features, such as access roads or construction platforms.

In load support applications, when a static or dynamic load is applied to a geocell-reinforced layer, lateral earth pressures are mobilized and transferred across a three-dimensional network of interconnected cells. The layer essentially performs like a composite material, facilitating a phenomenon known as the mattress effect. As a result, applied loads are more widely spread, resulting in a uniform distribution of applied stresses, as well as a reduction in the magnitude of these stresses to underlying layers. This results in an effective increase in the allowable bearing capacity and a reduction in differential settlement.

Moreover, in many cases, geocells allow for the beneficial reuse of on-site materials, eliminating the need to purchase expensive aggregate or imported structural fill. These advantages not only offer the potential for savings in overall construction costs, but they also contribute to a significant reduction in carbon emissions due to less aggregate/fill processing, transportation, and handling.

GEOWEB® Geocells: A Versatile Site Development Solution for Solar Projects

The GEOWEB Geocells have been used for load support and foundation applications worldwide for more than 40 years. Developed in collaboration with the U.S. Army Corps of Engineers in the late 1970s, Presto co-invented the technology known today as geocells. Since that time, Presto has endeavored to improve and innovate geocell technology, creating what is known around the world today as the GEOWEB® Soil Stabilization System. GEOWEB Geocells are made of 100% high-density virgin polyethylene and do not contain any recycled material, fillers, or exotic polymer, all of which can negatively affect performance. Complete with a full line of accessories for ease of installation and long-term performance, the GEOWEB Soil Stabilization System is the most advanced geocell technology in the industry.

photo of solar panels on solar farm with blue sky and clouds background

The GEOWEB system has been used on every continent and on thousands of load support, slope stabilization, channel protection, and retaining wall projects. Based on accredited third-party laboratory analysis using internationally recognized test methods, The GEOWEB geocells are predicted to be durable for a minimum of 50 years and are extremely resistant to long-term weathering and UV degradation. This makes the GEOWEB Geocells an ideal site solution for solar projects that must withstand the long-term effects of climate change and extreme weather events.

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.

Related Articles and Case Studies

How GEOWEB geocells were used to combat severe erosion at the Spotsylvania Solar Farm

The History of Geocells

Posted by Ashley Beyer

Geocell technology has come a long way over the past four decades. In its early days of development, the geocellular soil confinement system consisted of wax-coated craft paper; a plastic drainage pipe matrix fastened with staples; paper-thin, hexagon-shaped, glued aluminum; low- and medium-density recycled materials; pure polyethylene without UV stabilization; and square cells similar to old-fashioned egg carton separators.

The Invention of Modern Geocell Technology

In the late 1970s, the U.S. Army Corps of Engineers (USACE) contacted Presto Products Company—a private-label consumer packaging manufacturer—to develop a more robust honeycomb-shaped confinement system that would maintain load-bearing strength under heavy vehicle loads.

Working with Steve Webster at the Waterways Experiment Station (WES), Presto’s Gary Bach devised a method to weld polyethylene strips to form a cellular structure. This innovative system became known as Sandgrid and was used by the military primarily for road applications.

After the development of Sandgrid, Presto Products created a new business unit to focus solely on the geosynthetics business. With this expansion, Presto Geosystems® was established.

Presto Geosystems and the USACE tested various resin blends and concluded that virgin high-density polyethylene (HDPE) provided superior weld consistency and structural strength. Presto Geosystems introduced the GEOWEB® Cellular Confinement System (CCS) to the geosynthetics market in the early 1980s.

In the years following the initial testing, the geocell technology continued to advance, paving the way for the use of geocells in new civil and military applications. In addition to a load-support solution, the GEOWEB system provided soil stabilization for the rapid construction of fortified walls in the United States’ Middle Eastern combat zones, starting with Operation Desert Storm in the early 1990s.

The GEOWEB System’s Big-Screen Debut

The GEOWEB system made its Hollywood debut in the 1994 sci-fi action-adventure movie, Stargate. To serve as the desert landscape in the film, filmmakers chose the barren setting surrounding Yuma, Arizona. However, very loose sands at the film location made transportation around the site virtually impossible. Crews used the GEOWEB system to create an “instant road,” using on-site sand as the infill, that allowed vehicles and heavy equipment to move around the desert with no rutting or loss of traction.

Director Roland Emmerich stated, “We never would have been able to move around the desert without [GEOWEB].”

Fast-Forward to Today’s GEOWEB Geocells

The GEOWEB system did not let fame go to its head, but these early applications and projects did help cement its stardom in the world of geosynthetics. Since its introduction in the 1980s, the GEOWEB Soil Stabilization System has been used on every continent and on thousands of load support, slope stabilization, channel protection, and retaining wall projects.

Presto Geosystems is a leader in the stormwater and site development industry with eco-friendly, custom-tailored solutions to meet the most demanding soil and water problems. We have been manufacturing high-quality, innovative products for over forty years. Our proven solutions are designed to handle unique challenges, lower project costs, and reduce construction time with minimal environmental impact. Our products are backed by accredited research, internationally recognized testing, and quality processes, ensuring high-performing and long-lasting solutions.

We are committed to the complete project cycle. We invest with partner engineers, contractors, and owners to solve their site challenges. Our value starts with design assistance, and we stay with you through project completion.

Our Mission is to Give the World a Strong Foundation to Build On.

With the commercialization of geocell soil confinement technology in the early 1980s, Presto Geosystems made history as one of the early pioneers in the world of geosynthetics. Four decades later, that innovative spirit is as alive today as it was at the beginning of our journey. Our products have been used on every continent and on thousands of projects to improve infrastructure reliability and environmental quality for communities around the world. We believe in the human spirit of innovation, and we believe that reliable infrastructure and environmental quality are foundational to the prosperity and well-being of the world’s communities.

Design Support & Resources for GEOWEB Applications

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

Download The History of Geocells Article >>

Advancing the Mining Industry’s Transition to Sustainable Practices with Geosynthetics

Posted by wpengine

Written by: Michael Dickey, P.E. (WI, FL, GA, NC)

Mined materials are essential to our everyday lives. We use these valuable minerals in nearly every sector of the economy—they are necessary to construct roads and buildings, manufacture vehicles, build computers, and generate electricity. Additionally, the mining industry stimulates economic growth by providing employment opportunities and generating tax revenue that helps fund vital public services, such as hospitals and schools.

As the mining industry navigates environmental, social, and governance (ESG) issues, there is a sense of urgency to adopt sustainable or “green” mining practices. Green mining can be defined as technologies, best practices, and mine processes that are implemented to reduce the environmental impacts associated with the extraction and processing of metals and minerals.

The Mining Industry Faces Unique Challenges

When it comes to sustainable development, operation, and closure of mines, the industry faces myriad challenges—not the least of which are poor soil conditions, weak subgrades, and other geotechnical challenges that can complicate miners’ efforts to meet ESG goals.

In this regard, some of the more common geotechnical challenges that mine operators must contend with include:

  • Constructing and maintaining heavy-duty haul roads.
  • Stabilizing and protecting slopes.
  • Tailings management and site reclamation.

Compared to conventional methods, integrating geosynthetics into designs can help achieve a more sustainable approach to overcome many of these types of geotechnical challenges.

Heavy-Duty Haul Roads

Haul roads are an integral asset to a mining operation, in the same manner as trucks and shovels. They are a critical component of mining infrastructure, and they directly influence the operational efficiencies of mine sites. Haul truck payload capacities range from 36 tons up to a staggering 450 tons (for ultra-class trucks), so these roads require special design considerations to withstand heavy and continuous traffic. However, extreme weather conditions and soft subgrades present challenges to both the construction and long-term performance of heavy-duty haul roads.

At a gold mine in Latin America, owners adopted a value engineering approach to optimize haul road design and minimize long-term costs associated with recurring maintenance and repair. They accomplished this by using the GEOWEB® Cellular Confinement System to stabilize and confine road-base materials. The geocell system allowed for the beneficial use of abundantly available coarse river sand for the placement of base materials.

GEOWEB mining haul road

Due to the improved bearing capacity of the system, there was also a substantial reduction in overall section thickness requirements. This resulted in construction savings of over $150,000 per kilometer. Additionally, because of improved road stability, mine operations saw a 65% reduction in maintenance costs as fewer grader passes were needed and requirements for frequent replacement of wear course materials were substantially reduced.

Slope Protection

In addition to haul-road applications, geocells can be used on slopes to resist sliding, prevent severe erosion from surface runoff, and facilitate the construction of steep slopes.

The New Caledonia mine in the South Pacific—one of the largest nickel mining sites in the world—faced the formidable challenge of protecting the mine slopes from erosion due to highly erodible soils, mountainous terrain, and extreme weather (cyclones).

The owner ultimately selected a slope protection strategy consisting of the GEOWEB geocells infilled with waste aggregate. The GEOWEB Slope Protection System was designed to perform as a robust protective veneer over the existing terrain. The beneficial reuse of readily available onsite materials meant direct cost-savings to the owner compared to previous, less successful methods.

geoweb mining slope

Tailings Management and Site Reclamation

Tailings are waste products that result from mining, crushing, grinding, and chemically treating ore. Tailings storage facilities typically contain crushed rock, water, and chemicals, and are designed to prevent the uncontrolled release of material into the environment during operation and closure. These facilities are often set up as settling ponds that are later capped in place during site reclamation activities.

At the Moon Creek abandoned mine site in Idaho, for example, reclamation efforts included the construction of a tailings repository for onsite disposal of approximately 88,000 cubic yards of flotation tailings, contaminated soils, and waste rock. Project objectives were to reduce the release of heavy metals to Moon Creek, rehabilitate the site to limit human health and ecological exposures, and improve trout habitat.

The tailings repository was built on a special foundation, allowing its construction over soft, saturated in-situ tailings. Foundation elements included an impervious below-grade scour-protection berm, gravel and limestone wick drains, and a GEOWEB mattress filled with waste rock to provide a surcharge over the tailings and lateral load reinforcement.

Following the placement of waste materials, the repository was covered with an engineered cap composed of a geosynthetic clay liner, overlain by a gravel drainage layer and two feet of soil. Lastly, an erosion protection mat was installed over the surface of the cap to provide root matrix reinforcement for the native grasses used in the seed mixture.

geoweb mattress

Design Support & Resources for Mining Applications

The engineering team at Presto Geosystems works closely with civil engineers, offering free project evaluation services and on-site support for mining haul roads, slope protection, basin containment, channel armoring, and tailings protection.

Innovative Design of Sludge Drying Beds Using 3D GEOWEB® Geocells

Posted by Ashley Beyer

 

Wastewater treatment facilities have long had to contend with the challenge of dewatering sludge to minimize waste and achieve overall cost efficiency for disposal. Large-scale facilities commonly use mechanical filter presses or centrifuges to dewater sludge. This equipment is often too cumbersome and expensive for many smaller facilities, so they rely on sand filter drying beds for sludge dewatering. Because small tractors or loaders cannot be operated on the loose sands of a conventional drying bed, a system must be implemented to stabilize the sand and improve load distribution for routine cleanout operations.

Transforming Infill Material with the GEOWEB® Geocells

GEOWEB geocells

GEOWEB 3D Soil Stabilization System

Through an interconnected honeycomb-like network, 3D geocells confine and stabilize soils that would otherwise be unstable under loading conditions. Geocells are efficient and economical for fast-built unpaved roadways and retaining walls, erosion control of slopes, and stormwater channel protection. The GEOWEB® 3D Stabilization System is the industry’s most complete geocell system, designed with fully engineered components to withstand the most challenging site problems. Made from robust high-density polyethylene (HDPE) since conception, GEOWEB geocells offer the highest, longest-lasting, and most proven performance of any geocell system in civil applications.

The GEOWEB® System Improves Clean-Up System for Solid Waste Treatment Facility

A solid waste treatment facility in Florida was using vacuum-assisted drying beds to dewater chemically oxidized sewage sludge, but they were experiencing costly maintenance issues. The material deteriorated under constant use, and replacement costs were high.

The facility required a solution that would allow them to operate a small tractor over the sand filter bed to remove the sludge. They chose the GEOWEB® 3D Confinement System because of its ability to support vehicular traffic over poor soils. The GEOWEB system provides complete structural support by limiting lateral movement of the confined material—in this case, very loose sand. The GEOWEB system was installed in the top layer of the loose material in one of the two sand filter drying beds.

The 10-inch-deep top layer was composed of uniformly graded filter sand, and below this was a graduated layer of river gravel. A geonet material was placed on top of the graded layer to ensure efficient sand placement. The complete cross-section consisted of a 2-inch sand layer placed over the 8-inch sand-filled cellular confinement system underlain by the geonet and gravel bed below.

After installing the multi-layer system, cleanout operations significantly improved. With the new system, cleaning the sand drying bed requires moving only one to two inches of sand that contain the sludge and allows the crews to load and clean one 1,700-square-foot drying bed in 48 hours, unlike the original system which could take several days. The GEOWEB Cellular Confinement System also acts as a natural depth gauge for the front end loader, the blade of which can easily be used to backdrag the final few inches of material during cleanout to protect the system against damage and preserve operational integrity. Overall, the GEOWEB system reduced maintenance costs for the facility by 50 percent.

Request a free project evaluation.

Building Energy Roads in Harsh Conditions With the GEOWEB® System

Posted by Ashley Beyer

oil road

Energy sites are often located in remote and difficult-to-access sites in environments with poor soils, limited road-building resources, and extreme weather conditions.

Site Challenges in Western Canada

In Western Canada’s Oil Sands region, transporting construction equipment, drilling rigs, and completions apparatus – all with heavy wheel loads (typical loads exceeding 125,000 lbs.) is the challenge. It can be extremely difficult to accomplish this over the soft, wet ground (thick muskeg and saturated clays) typical of this region. Add the challenge of working in the dead of winter in below-zero temperatures and on frozen ground, with limited road building materials, and the scenario makes accessing the sites extremely difficult.

In the wettest months, muddy conditions can make access by heavy trucks and equipment nearly impossible. So, energy companies typically wait for the ground to freeze before ramping back up construction.  Even in winter, access to remote oil sites creates challenges including undeveloped roads, soft ground, and scarce materials suitable for constructing roads.

A Road Solution Built for Extreme Conditions

The GEOWEB® 3D Soil Confinement System is built for these challenges.  The all-weather HDPE material is fast to install and isn’t hindered by soft ground or extreme temperatures.

geoweb road

GEOWEB® 3D technology allows the use of low-cost, local fill—such as sand—and literally transforms it into stable, long-lasting, and low maintenance access roads and pads.  The confined infill creates a stiff road surface that is resistant to movement, preventing concentrated rutting and resulting in faster cycle times.

The compact GEOWEB material is economical to transport and fast to install on-site without heavy equipment or specialized crews, minimizing environmental impact and disruption of the land. Most importantly, confinement technology reduces base construction costs by using 50% less fill.

Resourceful Access to Energy Sources

The GEOWEB® 3D system is a low-cost and efficient way for energy companies to overcome these challenges and access their oil & gas, wind, and mining sites—even in some of the worst site and weather conditions.

Presto offers free project evaluations and site support.

Women in Engineering: Meet Sam Justice, P.E., Design Engineer at Presto Geosystems

Posted by Ashley Beyer

 

International Women in Engineering Day (INWED) takes place every year on June 23 to celebrate the work and achievements of women in the field of engineering. INWED provides an opportunity to raise the profile of women engineers and highlight the career opportunities available in this industry.

Historically, women have been under-represented in the academic and professional engineering fields; however, numbers have increased over the years. In 1960, about 1% of all engineers were women. In 2019, women made up approximately 20% of the engineering workforce.

Organizations like the UK’s Women’s Engineering Society (WES) hope to see these numbers grow even more as they work to provide young women with resources and opportunities that encourage them to pursue careers in engineering. The organization launched Women in Engineering Day in 2014, and the holiday became globally recognized in 2017.

Each year, people participate in hundreds of INWED events across the globe. In honor of INWED 2021, we’re sitting down with Presto Geosystems’ very own Civil Design Engineer, Sam Justice. Backed by a decade of specialized engineering experience, Sam is an accomplished civil engineer with a proven history of guiding complex projects to successful outcomes. She holds a geotechnical engineering degree from the University of Michigan and a geological engineering graduate degree from Michigan Technological University. She is also a registered professional engineer and an active member of the American Society of Civil Engineers (ASCE) and the Society for Women Engineers (SWE).

How or why did you choose engineering as a career path/area of study?

SJ: I always wanted to be an engineer, pretty much as soon as I knew engineers existed. I always loved knowing how and why things worked, and more than that, I want to know how things fit together with the rest of the world. That is the difference between a scientist and an engineer for me. It is awesome that we have people who can spend years studying a single thing, like trying to discover a new subatomic particle. But, to me, the people who would take that new knowledge and do things with it and help people with, are the ones I wanted to be. I saw engineering as the path to being able to do something tangible in the world and be able to point to something, and say “that thing works because of me.”

Where did you study engineering?

SJ: I completed my undergraduate in Geotechnical Engineering at the University of Michigan (Go Blue!). Once I finished that degree, I took a break from school and worked for a few years at a consulting firm. Then I decided to go back for my Master’s degree in Geological Engineering at Michigan Technological University.

What is the most exciting thing about your job?

SJ: In my job, I am essentially a consultant, rather than a project engineer. So instead of focusing on one or two projects at a time, I am a part of a dozen different projects every week. It’s exciting to see the variety of projects that are happening at any moment, from small home improvement projects to multi-million-dollar private company jobs. Moving from one type of work to another so quickly keeps me feeling energized about what I’m doing, and definitely doesn’t leave room for me to get bored.

What does a typical day in your role look like?

SJ: Usually, I spend my days reviewing project information for an engineering or contracting firm and providing my recommendations and expertise on a construction or remediation strategy. I can be pulled into the beginning, middle, or end of a project, so I have to make sure I know what the clients are hoping for, and what is realistic based on what has already happened. I also spend a lot of time talking directly with people, either about a specific project we are working on or through hosting learning webinars for our industry. There are a lot of questions about the geosynthetics industry, and I try and answer them the best I can.

What is it like to be a woman working in a historically male-dominated industry?

SJ: It can be tough, no doubt about that. But things are changing for the better every year, and it’s becoming less of a male-dominated job all the time. There is still some sexism, mostly in the form of someone being surprised that a woman is in charge of providing recommendations or teaching classes. I counter that by just knowing my work and having confidence that my knowledge is valid and sought after. Other engineers are getting more accepting of women in the industry, and the industry itself is catching up to the times, but it’s not always a smooth road. But it’s worth it, I think, to get to do things I do, even if there are still some people who think I shouldn’t have a seat at the table. I like to think that what I do is making it a little easier to be heard.

Have any women in the engineering world influenced you? How?

SJ: I had a professor at Michigan who really inspired me to know that I could make it as an engineer. She taught classes, was a senior member of a consulting firm, spoke at conferences, and regularly told government departments; I swear she did it all because she really loved what she did and believed that she could do it all. To her, it didn’t matter that she was a woman, or that she was an immigrant, or that people told her she should be doing something else. She had knowledge that others didn’t and was enthusiastic about sharing it with everyone. I try to model the way I teach after her, and I know it has made a difference and made me a better engineer.

What are you most excited about when thinking about the future of engineering?

SJ: The civil engineering world, and the geosynthetic industry, in particular, is constantly evolving, coming up with new ways to complete projects faster and cheaper, and greener. I love the shift towards green infrastructure and low-impact development. Construction and landscaping are some of the most immediate and impactful ways to help our planet, and I can’t wait to see what we come up with next.

What advice would you give to young women who are interested in pursuing a career in engineering?

SJ: Don’t be afraid to be passionate about being curious. Don’t ever let someone stop you from asking questions and getting answers. Being an engineer can be a daunting amount of work, but you’ll never be bored, and you’ll learn more than you can imagine. There is so much satisfaction in knowing the how’s and the why’s about something. And engineering is such a broad term! There is no limit to what you can do with an engineering degree, and it opens so many doors. It sounds cheesy, I know, but it really is a great career path, because you can make it whatever you want it to be. You just have to want to ask the questions and keep digging until you get the answers.

 

Innovative Solutions for Designing & Constructing Transmission Line Roads & Substations

Posted by Ashley Beyer

Energy SiteWhen natural disasters, power surges, accidents, or general equipment failures threaten the reliability of the power grid, maintenance crews must be able to quickly and safely access transmission lines and substations to make repairs. Designing resilient energy infrastructure that ensures power companies have a reliable, regular supply of energy and contingency measures in place in the event of a power failure is crucial to their business and the communities they serve.

Build Sustainable Roads for Utility Transmission & Substation Access

Accessing sites in remote or undeveloped areas can present several challenges for the energy industry when it comes to building, operating, and maintaining power transmission lines and substations. Soft soils and low-water crossings can make it difficult for utility vehicles to safely and effectively reach sites for routine maintenance and emergency repairs. The GEOWEB® 3D Soil Stabilization System is ideal for shallow ground improvement applications and can easily be incorporated into unpaved access roads for transmission lines and substations. The GEOWEB geocells, made from an all-weather high-density polyethylene (HDPE) material, are durable, chemical resistant, and outperform standard two-dimensional geosynthetics through lateral confinement of infill materials, facilitating what is known as the “mattress effect” for distributing loads across weak subgrades.

The GEOWEB system offers an economical way to construct low-maintenance unpaved access roads that are fast to install and require less maintenance than their unreinforced counterparts. The GEOWEB-confined aggregate is stable and resistant to shoving and movement that can occur with unpaved access roads subjected to heavy-traffic loading conditions. With the GEOWEB system, roads are built with 50% less aggregate to support heavy vehicles with minimal environmental impact. The use of low-cost, local infill—such as sand or limestone—lowers the overall project cost, and the GEOWEB reinforcement extends the life of the unpaved road and reduces annual maintenance costs.

Reduce Touch & Step Hazards at Substations

Aggregate is commonly used for electrical substation pavements and transformer pads to create a safe, non-conductive insulation layer between workers and the ground. This aggregate must contain fines to create a stable surface to resist heavy vehicle stresses, and the presence of these fines can create touch and step hazards. The GEOWEB system allows the use of an open-graded base course (OGBC) with no fines, providing greater surface permeability and a more stable driving surface that resists rutting.

The permeable GEOWEB confinement system delivers exceptional drainage, which prevents the accumulation of dangerous surface water ponding. Roads and substation pads constructed with the GEOWEB system require virtually no maintenance and provide a safer environment for workers.

Case Study: Geocells Stabilize Soil & Manage Stormwater for Hospital Power Line Installation

The Alabama Power Co. (APC) saw a need to install a second substation to provide a reliable alternative power source for Providence Hospital in Mobile, Alabama; however, wetlands near the project site complicated installation of the substation and power line. Construction of the access road was also wrought with environmental and regulatory concerns from citizens and local officials.

Construction is strictly governed in wetland areas, so APC could not fill the wetland for soil stability. City of Mobile regulations required the project to establish stormwater retention areas due to its size. Rather than retain the water in ponds, however, APC used Presto Geosystems’ GEOWEB confinement system to stabilize the soil to ensure the access road was permeable in the upland portion of the project.

The geocellular system stabilizes the aggregate, preventing movement under vehicle loads, and allows stormwater to drain into the soil rather than run off and create problems for residents and the environment.

Because water so easily infiltrated the access road, Mobile did not require APC to build the retention pond per its regulations. Had an impervious surface been installed, stormwater would deviate from established flows, and nearby residences likely would have complained about stormwater on their properties.

The substation provided Providence Hospital with two sources of power. In the event of a power failure at one, electricity would shift to the other, keeping the hospital’s vital machinery online.

Design Support & Resources for Utilities & Electrical Transmission

The engineering team at Presto Geosystems works closely with civil engineers, offering free project evaluation services and on-site support for utility maintenance roads and substations.