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Choosing the Right Geocell

Posted by Katie Bocskor

Written By: Bryan Wedin P.E., Chief Design Engineer, Presto Geosystems

Not all geocells are created equal. While most manufacturers can provide similar-looking written specifications, you need assurances that the material delivered for your project is of the high quality that you expect. Important factors in the success of your geocell project include:

Quality

The geocell material is proven, strong, and will last

  • Require only the highest quality virgin High Density Polyethylene (HDPE) resin
    • Low quality or recycled resin can lead to weak and/or inconsistent seam strength, putting the success of your project at risk.
    • Non-HDPE materials cannot match the nearly 40 years of in-ground experience of HDPE geocells and plastic alloy proprietary blends can mask cheap stiff filler materials.
  • ISO Certification
    • Important, but the manufacturer sets the testing protocol for the certification. Require a Certificate of Analysis (COA) for the material that is shipped to your project. An ISO certification that does not require continuous testing is lacking.

Integral Components

The complete solution includes proper components

  • Non-corrosive, high-strength panel connection method (ATRA® Keys vs. weak staples or zip ties)
  • Anchors that provide secure connections to the geocell (ATRA® stakes vs. J-hooks)
  • Load Transfer Devices for tendon applications that are non-corrosive and offer a secure connection to the cell walls (ATRA® tendon clips vs. washers, knots or pipes)

Certification

The geocell material “as shipped” meets proven industry standards

  • Insist upon signed material certs showing the proper testing/certification for your application
  • Unscrupulous providers supply special material for testing and ship lower quality material

Design and Specification Support

You receive proper tools and engineering guidance

  • Require the manufacturer to provide project design assistance for their specific material. Variations of resin and of anchoring and connection methods on the market make it “critical that designs from one manufacturer not be used for alternate material.”
  • Require the manufacturer to provide a complete specification/submittal package

Installation Support

The contractor receives proper installation tools and training

  • Many contractors are not experienced in the installation of geocells. Require pre-construction training and on-site field supervision by a certified manufacturer’s representative to ensure your project is installed correctly and economically.

Certainty

Your owner and your reputation are protected

  • All of the above factors combine to provide you the level of confidence you expect from the material you specify. Why risk this certainty for the small savings (savings that come from the use of inferior resin, non-engineered components and a lack of project support) that come with allowing inferior, alternate material suppliers?

 

Bryan Wedin P.E., Chief Design Engineer, Presto Geosystems
P: (920) 738-1342
[email protected]
www.prestogeo.com

How long does it take to install geosynthetic construction products?

Posted by Ashley Beyer

How long does it take to install? It is a question we hear every day. When it comes to cost and installation rates for geosynthetic construction products, there are no simple answers to what seems like simple questions.

In fact, beware of those who try to simplify determination of installation costs for their products with quick answers or charts and tables to determine construction rates. Experienced project managers and site supervisors of the crews charged with installation are in the best position to estimate productivity rates. They know best their crew’s capability and the characteristics of the site involved.

The variables that need to be considered include:

  • Crew size, talent, work ethic and workday length
  • Temperature, precipitation and length of day (sunlight)
  • Experience with product class
  • Size of the project
  • Site Access
  • Site Conditions (see weather)

Crew

The optimum crew size is important. Too small and you may lose the benefits of assembly line productivity. Too large and you will find that you fall over each other and pay for extra “inspectors”. All crews are not created equally. The familiarity with tools and techniques vary greatly as does the work ethic both between crews and by region and country.

Weather

Cold temperature can slow down project installation rates, due to need for heavy clothes and gloves and can even affect the way materials go together. In some cases, frozen ground can aid installation on soil stabilization rates by allowing firm surfaces on which to work. Extremely hot weather can also negatively impact productivity rates. Rain never helps and even recent rain can change a site condition to make working estimates degrade. Sunshine is short in northern climates and visibility can shorten the workday in winter. Delays in projects that push a project start date by months can add days to a schedule as daylight and conditions change by season.

Experience With Product Class

Installation rates do not include training time. Industry leading manufacturers offer trained installation representatives and tools that can help shorten learning curves and get installation efficiency off to a quick start. Size of the Project.

Large sites lead to higher efficiency and greater installation rates. Invariably, installation expertise only matters if the installation duration > learning curve duration. Large projects also offer opportunities to stage work, use multiple crews, and create repetitive motion improvements.

Site Access and Site Conditions

Not only is close proximity to the roadway important, but one must consider the benefits of multiple access points if available. Location of material storage can create long sub delivery times within a single site. Long narrow sites can be a challenge as leap frogging workers is not practical and may force linear progression.

So, when we are asked what installation rates can be expected for Presto Geosystems GEOWEB® road, slope or retaining wall solutions; or when we are asked about the time to assemble our GEOBLOCK® or GEOPAVE® porous paving systems; or when a customer wants to know how long to assemble a GEOTERRA® construction mats; expect the questions to start….Just a few simple questions.

Our experts are here to help answer your geosynthetics questions. Meet the Presto Geosystems team >>

Impervious Gravel vs. Porous Aggregate Paving Systems

Posted by Ashley Beyer

Written by William G. Handlos, P.E.

For two decades, I held the position of City Engineer and frequently had to explain to disbelieving homeowners, developers and elected officials – that gravel driveways and parking lots were not porous. I would explain that for purposes of stormwater runoff, such gravel pavements must be treated exactly as we would concrete and asphaltic pavements. They often bristled at the idea that gravel did not percolate water and were upset to find that their gravel driveway, lots and roadways were assumed to shed 100% of rainwater.

So it is with more than a dose of irony that I now have found myself in the position of regularly explaining to local and state officials that aggregate pavements are not necessarily impervious. Stakeholders are so accustomed to repeating the impervious gravel mantra…that they forget to notice that porous aggregate is not the same thing as gravel. I think it is best to start with a primer on the vernacular.

Good Gravel and Good Porous Aggregate

A “good” gravel (Image 1) should have 40 to 70% stone, well-graded from 1/4” to 2-1/2” diameter; 20 to 50% sand; and 10% +/- fines. It should resist abrasion, shed water and be capable of being compacted.

A “good” porous aggregate (Image 2) should be poorly-graded from 3/8” to ¾” diameter; with 25 to 40% porosity. It should pass the heaviest of rainfall, is easily rutted/shoved and nearly impossible to suitably compact. Such good porous aggregate is often called open-graded base course (OBGC) when used under pavements.

Some municipal and state regulations continue to deem aggregate surfaces as impervious. This is due to inertia and old school thinking and it is past time to change these outdated standards. With the help of engineered high density polyethylene containment products, such as the GEOPAVE® porous paving system, OBGC porous aggregate can be stabilized to offer a highly porous, strong, abrasion resistant, rut proof, aesthetically pleasing and inexpensive alternative to porous asphalt or pervious concrete.

Injection molded and designed specifically for use with open aggregate designs, this system confines the otherwise unruly OGBC to individual cells with an attractive herringbone wall pattern that is designed to be seen and is reminiscent of a paver system. Resistant to frost heave when placed over an OGBC base for storage or sandy soils for fast infiltration, the system gives a very low cost alternative that is highly sought after by those municipalities seeking to meet demanding stormwater goals.

GeoPave® Porous Pavement System

Check to see if your local or state regulations allow for Porous Aggregate Systems and, if not; send a note to [email protected] with your location, the regulation, and a contact at the agency. We will follow up on all requests personally.

Porous Pavement Systems in Extreme Weather

Posted by Ashley Beyer

Porous Pavements

Customers are always coming up with new applications for our GEOBLOCK® Turf Protection System, but the University of Wisconsin-Madison just took it to another level. In early 2014, their Space Science and Engineering Center purchased the GEOBLOCK® Pavers to aid in staging their ice coring drills in Greenland and Antarctica.

The GEOBLOCK System was utilized for two specific applications.

The first application was for a footer under the frame of the drill tent(s). This application allowed the weight of the drill tent building to be distributed across the snow’s surface and provide support. Due to the GEOBLOCK System’s rigid design and load transfer tabs, the same characteristics that make it a strong, durable turf protection system, also delivered value over snow.

GeoBlock® Porous Pavement System

In the second application, the GEOBLOCK Units served as a flooring system inside the drill tent. Researchers liked the grid surface as it provided a non-skid surface and easy installation at sub-zero temperatures (-40°F). The rigid design also wasn’t affected by on-site drilling fluids (due to the non-reactive and inert polyethylene construction).

The GeoBlock® Porous Pavement System Works With A Variety of Infills

Researchers also capitalized on the light-weight design and reusability. The remote location required air-lifting the material and hand construction. The GEOBLOCK® system proved it can deliver results, even in the most extreme conditions.

Learn more about the GEOBLOCK Pavers >>

Request a Quote >>

The Market for Lightweight Construction Mats

Posted by Ashley Beyer

Written by William G. Handlos, P.E.

Lightweight Construction Mats

Construction access in soft soils present a common challenge engineers and project managers face while attempting to complete a project on-time and within budget while avoiding scheduling delays and associated costs. These soft soil sites may also be located in remote, difficult to access areas making construction impossible without a good site access system. Popular construction mat systems are made out of a range of materials including timber, laminate, steel and composite mats. They can be effective, but are also costly. They can also put laborers at risk as they require heavy equipment to install. The ideal mat system for access road construction would be designed to have a high utility-to-weight ratio and would deliver an eco-friendly alternative to current technology.

A lightweight construction mat system made from high density polyethylene (HDPE), GEOTERRA®, was created by Presto Products in 2003 to meet the needs of major oil and gas companies working in remote areas of the Amazon jungle. Transporting materials to these sites by helicopter precipitated the need for light, yet strong mats for work platforms and roadways. As the first of its kind, the mats capitalize on the sustainable characteristics of recycled polyethylene and offer an efficient, lightweight design for a variety of remote access applications.

The GeoTerra® Portable Mat System is an efficient lightweight construction mat system.

Lightweight portable mats are easy to deploy and install without heavy equipment, even in remote areas such as for oil & gas access and platforms.

Typical construction mat applications include working platforms for oil and gas exploration as well as maintenance and access roads to transmission lines, pipelines, wind power generation, and mining operations. In addition, construction mats have also been used in a variety of other applications including walkways in soft soils, storage pads and helipads. The GEOTERRA® mat system may also be used as a tracking pad to remove excess soil from vehicle treads. This may mitigate problems associated with the use of traditional aggregate tracking pads which are difficult to work with, costly and hard to remove.

Lightweight HDPE mats are installed without heavy equipment. This decreases the risk of injury and minimizes equipment needs for construction site access. Utilizing a steel torsion tightened “PadLoc®” these mats provide strong connections for load transfer between sections and may be pre-assembled for quick installation in remote site applications.

This lightweight mat system does not degrade, weather, or leach into the subsurface as it is made from up to 97% recycled polyethylene. The ability to dissipate pore water pressure over the existing soil is essential to providing a safe, dry working surface for construction equipment and workers. The high strength geotextile underlayment eliminates soil upwelling in open cells and will allow the system to “float” over poor soils If the underlying soil is pervious, the open cell mat design allows it to act as a porous pavement which reduces the necessity for extra drainage components. If that is not the case, a one or two-sided geocomposite may be used in conjunction with the mat system to effectively direct the precipitation off of the working surface.

The GeoTerra® Portable Mat system helps bridge soft. organic, soils while supporting heavy loads

The strong, permeable mats effectively bridge soft or organic soils while supporting heavy loads.

Even the most difficult site challenges can be overcome by combining lightweight portable mat systems with the correct under layer and anchoring system. Very soft soils with a CBR (California Bearing Ratio) of two or less may require additional load support which may be provided by cellular confinement (geocell) systems.