The chemicals and heavy metals that are left behind or dumped by factories and manufacturing facilities often linger in the ecosystem and contaminate food and water resources. Land remediation can take a huge amount of time for each site, not to mention money and legal complications. Heavy metals, such as lead, mercury, and arsenic, and chemicals like volatile organic chemicals (VOCs) from fuels and solvents and polychlorinated biphenyls (PCBs) from electronic equipment are particularly prevalent in post-industrial land. Human exposure to contaminated soil, water, and food can cause anything from minor health issues to life threatening diseases such as cancer.
In the past, land remediation was done solely via excavation. This literally involved digging up the polluted soil and stone and moving it to a landfill zoned for hazardous materials. Land was then replaced with clean soil.
When toxic contaminants settle on the bottom of bodies of water, it is removed in a similar process called dredging. In this process, tankers remove the contaminated sediments and sludge into a machine, separate the chemicals and heavy metals from the water via filters and chemicals, and put the cleaned water back. The contaminated sediment is then moved to an appropriate landfill.
There are alternatives to excavations that are less invasive, such as stabilization, solidification, and bioremediation. The goal with stabilization is not to remove toxic or hazardous materials, but to stabilize the molecules to a state wherein they are not harmful to humans or the ecosystem. Chemicals or complementary compounds are added to the contaminated land to combine with the toxins to produce stable, non-hazardous compounds. This can be done by spraying the additives on top of the land or by dispensing the additives in liquid or gaseous form through pipes pushed deep into the soil.
Solidification is the process of adding chemical reagents that will combine with the toxins in contaminated water and sludge to make solid compounds that can be separated from or filtered out of the water. This way the water is left in the natural ecosystem but the chemicals are removed. Bioremediation involves adding specific bacteria or plants that feed on the contaminated particles and create harmless byproducts. These organisms must be chosen carefully as they often multiply considerably with no natural predators.
The use of underground storage tanks (“USTs”) for fuels and other liquids has many advantages. These include space considerations, appearance, fire safety, and protection from the elements and from vandalism. However, unless installed and maintained properly, USTs have the potential for leakage from the tank or related piping. These leaks can exist undetected for years and cause pollution of the surrounding soil and even groundwater. Materials of Construction USTs are usually made from either steel with a protective coating, or of fiberglass. Selection of UST type may depend on use and installation location. Fiberglass tanks are typically unsuitable for storage of heated materials, and for high load locations. However, they are lower maintenance and are not susceptible to corrosion. Steel tanks must be coated with a corrosion resistant coating, and corrosion protection is required. Contact plates at the bottom of the tank under fill and measurement ports should be installed. This prevents wear from measurement sticks hitting the bottom of the tanks. Piping is usually steel with a protective coating, or fiberglass. Other piping material may be copper or hydraulic flex hosing. Piping can be the same material as the tank or different. Metallic piping must be coated with a corrosion protective coating, and corrosion protection is required