Frequently Asked Questions
Why would we put something like glass into the environment? Wouldn’t that be dangerous?
Well, the reality is that recycled glass sand is mostly silica, like the natural sediment found in our region (Louisiana). This may not be the case for every region though, which is why it’s important to conduct extensive research before using this material in the environment.
Wouldn’t the glass be sharp and cut people or animals?!
Not necessarily, but it does depend on how the glass is crushed. When we analyzed the angularity of the sand produced by Glass Half Full, we found that less than 1% of sand grains were sub-angular and none were angular or very angular, similar to sand dredged from the Mississippi River.
Couldn’t there be contaminants in the glass? Like from colorants or labels?
We found trace amounts of heavy elements used in glass making, but levels were either comparable to or less than levels found in our native soil like for barium, or well below regulatory levels, as shown for lead.
Furthermore, no potentially hazardous elements leached out of the sand during standardized testing that simulates soil-to-groundwater transmission.
In terms of labels and adhesives, the glass pulverizing process removes nearly all non-glass contaminants from the glass sand product we use for restoration. We confirm this with regular testing as well.
Can plants even grow in glass sand?
Absolutely! In greenhouse experiments, marsh grasses and willow trees grew as well in a mixture of glass sand and sediment dredged from the Mississippi River as they did in the sediment alone. This is good news for us because in any restoration project, we would expect the glass sand to gradually mix with the native soil in the environment.
Why use glass sand over conventional dredged sand?
Sand is the planet’s most exploited resource after water so, realistically, we cannot keep mining and dredging the amount of sediment needed for coastal restoration projects. Solving our land loss crisis requires convergence of all types of ideas and glass sand is an important part of that solution.
Why not use the glass to make new glass instead?
Recycling glass into new glass requires more capital and energy than simply crushing it into sand. In the gulf south, we do not have a glass manufacturer nearby that we could transport the crushed glass to, making it more economically and environmentally taxing. Creating an entire glass manufacturing plant would require a huge amount of capital. So, instead of allowing glass to continue going to the landfill, crushing it into sand and finding ways to utilize that sand is a much better option.
Does the recycled glass sand grain size matter for coastal restoration?
Absolutely! Our research is centered around finding the best grain size for each specific region or coastal project. For wetland restoration in Louisiana, a coarse grain size works well for the ecology as well as erosion resistance. However, for a beach restoration project, it’s important to match the grain size of the sediment that is already there, which is usually more of a fine sand.
Will recycled glass sand work for restoration in my coastal community?
It depends! Not all sand is alike and you will need to understand the materials that make up the natural sand in your area. Recycled glass sand works well in Louisiana because it is made of silica and very similar to our natural quartz-based sand. Depending on your geographical location, your natural sand may consist of other materials such as shell, coral fragments, and volcanic rock. Introducing recycled glass sand into an environment dissimilar to silica may not be beneficial and thorough research will need to be conducted before attempting to do so!
Is crushed glass cancerous?
When people have concerns about the safety of crushed glass they are usually worried about Silicosis, a lung disease caused by breathing in tiny bits of silica. An important distinction with recycled glass sand is that it contains amorphous silica as opposed to crystalline silica which causes silicosis. The World Health Organization classifies crystalline silica as carcinogenic to any animal or human. Amorphous silica, on the other hand, is not.