Written By: William G Handlos, P.E. Does a porous pavement solution cost more? Porous pavements are less expensive to install than impervious concrete or asphalt when you consider total project costs. When evaluating parking lot construction costs for porous pavements vs. impervious alternatives, you must consider the following cost “buckets.” Traditional pavements such as bituminous asphalt or Portland cement concrete enjoy low cost and ubiquitous installation contractors. This information may lead one to think that choosing a porous pavement would lead to higher overall project costs, but that is a myth because almost everything else about traditional parking lot construction is far more expensive than the porous pavement alternative. Traditional hard-surface pavements require inlet structures, castings, and covers for inlets and manholes, underground pipes, outfall structures, and detention ponds. Costs & Maintenance of Stormwater Ponds Detention ponds have three major cost drivers. Land costs to locate a pond can vary wildly depending upon commercial real estate values, but it is not unusual for land to be upwards of $250,000/acre even in small markets. The impact of the land utilized for detention ponds does not end there. Lost rental or income value is another cost consideration. Ponds take up valuable commercial… Read more »
Posts By: Katie Bocskor
Porous Pavements Myth Busters: Snow Removal
Written By: Samantha Justice, P.E. What You Need to Know About Removing Snow from Porous Pavements Vehicle and pedestrian use on porous pavements don’t stop because it’s winter. Roads need to be plowed, parking lots need to be cleared, and walking paths need to be snow and ice-free for safe use. This is true for all surface types: concrete, asphalt, and porous pavements—however, it is a common misconception that snow removal is more challenging with porous pavement systems. Myth Busted: Snow removal on a Porous Pavement System (PPS) is easy! Get the answers below to the frequently asked questions about removing snow from plastic, modular type porous pavers. Can I Apply Salt to Porous Pavements? Applying salt or ice melt chemicals to gravel-filled PPS surfaces encourages snow and ice to melt, the same as it would on a concrete road. Most porous paver units are made with High Density Polyethylene (HDPE), a strong plastic that has a high resistance to environmental factors and is chemically inert. Cold temperatures and freezing and melting snow or ice will not cause damage or deformation to the paver material. Most importantly, HDPE is chemically stable, so it will not react to applied deicers,… Read more »
Porous Pavements Myth Buster: Clogging
Written By: Bill Handlos, P.E. Not All Porous Pavements Clog Well-designed porous pavement systems resist clogging When designing porous pavement systems, it is important to consider the effects of silt, grit, sand, and other fine material that can slow or stop water from infiltrating. However, it is a common myth that all porous pavement systems eventually clog. A good PPS system design, simple but effective site design, and careful construction inspection and field guidance can all but eliminate the clogging threat. System Design Do’s and Don’ts Cross-sections will vary according to the porous pavement selected, but following some simple practices can ensure a successful system with long-lasting percolation. Never place filter fabric immediately below the porous pavement surface. Whether you are using pervious concrete, porous asphalt, polyethylene injection-molded paving block (such as GEOBLOCK vegetated or GEOPAVE aggregate PPS), or concrete paving stone, your cross-section should allow free flow from the paving layer to the base and storage layers. The last thing you want is to trap water in your pavement layer. Surprisingly, at least one aggregate PPS manufacturer sells their product with a filter fabric attached to the bottom of the units. Always use a filter fabric or other separator at the bottom of… Read more »
Porous Pavements Myth Buster: Winter Durability
Written By: Bill Handlos, P.E. Properly designed porous pavement systems will not be damaged by the dynamics of freeze-thaw cycles. For decades, civil engineering roadway designers have been trained to use positive drainage, crack sealing, and sealcoating to keep the area under pavement dry. The prevailing mentality was to use a well-graded, tightly compacted base under impervious concrete or asphalt wearing surfaces. When water gets between the well-graded base and the impervious surface, frost conditions would lift pavements, weaken the base structure, create potholes and, in general, wreak havoc with the life of the pavement. So, it is not surprising that age-old tenets related to moisture, seepage, and freeze-thaw cycles get mistakenly applied to porous pavement systems. What makes well-designed porous pavement cross-sections so resistant to the power of freezing and expanding water? The answer is space. Poorly graded crushed aggregate offers up to a 40% void ratio, which gives water a place to move and expand upon freezing, and a network of pathways to drain. High void ratio systems allow the Earth’s natural warmth to move up from below the frost line into and through the open-air system just as water and ice-melt move through the system. If… Read more »
Porous Pavements Myth Buster: Winter Maintenance
Winter Maintenance for Porous & Pervious Pavements Porous pavement systems are a great way to reduce the amount of stormwater runoff on your site and incorporate Low Impact Development (LID) practices. One of the simplest ways of creating a porous pavement area is to confine unbound aggregate in a rigid paving unit such as the GEOPAVE® Aggregate Porous Paver. The GEOPAVE system is similar to pervious concrete and porous asphalt solutions, but is usually both less expensive and easier to install. Porous Pavements Are Difficult to Maintain in Winter Weather Conditions. NOT TRUE! The GEOPAVE Gravel Pavers are easy to maintain, and requires no special equipment. GEOPAVE parking lots or low volume roadways can be maintained in much the same way as a regular concrete or asphalt surface. An unbound aggregate system has many maintenance benefits over other porous pavement systems. Look at the table below and you’ll see how the GEOPAVE system beats pervious concrete and porous asphalt every time. (Click Chart to Zoom) The GEOPAVE rigid porous pavement system is comparable to standard paving materials, and a cut above other porous pavement systems. GEOPAVE systems have all of the benefits of hard surface porous pavements—fast… Read more »
Railroad ballast performance improvement using GEOWEB® Geocells
Each year railroads must allocate a significant portion of their capital and maintenance budget toward the creation and upkeep of high-quality ballast layers. Enduring, well-designed ballast is quite literally the foundation on which a successful rail line operates. With ballooning rail traffic carrying heavier loads than ever, GEOWEB cellular confinement (geocell) effectively takes the pressure off critical ballast systems. Oregon State University (OSU) recently performed state-of-the-art, three-dimensional dynamic Finite Element modeling to analyze the reinforcing benefit of GEOWEB geocells in railway applications. Completed in cooperation with the University of Kansas (KU), who simultaneously performed a testing program of Geocell-reinforced ballast placed over weak subgrade. The digital modeling results were reinforced by the laboratory tests and showed a significant decrease in settlement of the railway ballast when GEOWEB confinement was used. Using the GEOWEB system not only decreased settlement but also reduced pressure on point-to-point aggregate load transfer contact. This resulted in less damage to ballast aggregate particles leading to less progressive deformation and longer maintenance frequencies of the entire ballast embankment. In short, more cycles mean less track down-time for maintenance. The research results were clear. The benefits of applying GEOWEB Geocell confinement for reinforcement of real ballast over weak… Read more »
Bringing Stability to an Unstable World
With this summer’s extremely wet weather conditions across the country, building access roads is a major challenge. Muddy, soft ground is causing construction delays when it comes to moving heavy vehicles and equipment over the soft soils. Presto’s GEOWEB® Soil Stabilization System offers a way to build roads even with these site challenges using low-cost, local fill—and has been doing so for over 30 years. In fact, the GEOWEB system is the go-to solution for many oil companies in remote areas like the Canadian oil sands and the Amazon basin. Recently, EnergyNow Media featured an article on GEOWEB roads addressing the latest access challenges in the energy sector. The EnergyNow article is republished below. Reprint of recent article written by “EnergyNow Media” (North American Energy Magazine) Presto Geosystems: Bringing Stability to an Unstable World Oil and gas is a tricky business. Everything from resource extraction to site management to processing is fraught with difficulties, challenges, and trials. However, one often-overlooked aspect within this industry is that of simply being able to access the resource site in the first place. Once access is established, it’s crucial that there is a clean, stable platform to work on and transport resources back out…. Read more »
Choosing the Right Geocell
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… Read more »
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