Soil, groundwater contamination cleanup methods shifting to “sustainable”
Although „sustainability‟ is the new buzz word being used to that businesses care about the environment, there is no single standard defining “sustainable” activities and practices.
The dictionary defines sustainability as the act of maintaining or supporting an object, action or person. A footnote states that environmentalists define sustainability as acting to minimize the long term impact of man‟s actions on the environment.
Remediation should be an sustainable activity since it cleans up past problems. Due to public perception of the danger any amount of a contamination presented, clean up technologies have been designed and applied to remove the contamination as quickly as possible at any cost.
This demand for instant results spawn treatment technologies that need sizable power supplies and land to operate and often generate solid waste that is sent to a landfill. Many times the treatment systems create a public nuisance due to noise, odors, and visible appearance of the equipment and security fencing.
In today‟s business and political climate, applying any technology to remediate the environmental problem is giving way to designing a “sustainable” treatment process that will destroy or immobilize the contamination in place at a reasonable cost, use minimal resources, and with little or no impact to the neighboring property owners and current occupants.
As of yet, no regulatory agency or third party certifying body has created a set of guidelines defining “sustainable remediation”. Various forums and non-governmental organizations are trying to issue guidelines for the regulators to use but a final document has not been issued.
The basis for defining sustainable remediation is rooted in the definition of sustainability. The selected remediation technology must have a lesser impact to the environment that leaving the contamination in place.
The impact caused by remediation projects is no longer solely based on the cost to build and operate the system but includes other impacts such as the type and extent of interference the
installation and operation has on the use of the site and neighboring properties, final disposal site of contamination, type and quantity of secondary waste streams generated and what happens to the treatment system once cleanup targets are reached.
Adding these additional factors to the evaluation process will aid in selecting sustainable treatment systems that addresses the contamination without creating a greater adverse impact that doing nothing would.
For sites with concentrations of contaminates less than 5 times the cleanup target levels (CTLs), a risk based closure with or without controls is the sustainable solution. The detected concentrations are generally below site specific health based exposure limits especially if daily exposure is restricted by fencing or impervious surfaces.
Installing and maintaining a barrier or implementing procedures to restrict access are cheaper than excavating the soil or installing a mobile groundwater treatment system.
There is no construction or surface equipment to disrupt or temporarily stop site activities and the problem is not transferred to another location. The risk based closure is often used in other states to direct funding to sites with higher current adverse impact to the environment and human health especially if the responsible party pays to maintain the controls.
If contamination levels are greater than 5 times the CTLs, treatment technologies that destroy or immobilize the contamination in place should be studied along with the air sparge systems favored by the FDEP.
Factors used to determine which treatment technology is sustainable include more that equipment efficiency, reuse of warehoused equipment, minimizing operating and capital costs; and using electric power generated from renewable sources.
Sustainable remediation technology evaluations start with type of treatment selection; if the contaminate is destroyed in place or transferred to other locations for treatment or disposal; what type of construction activities are needed; amount of surface space needed by ex-situ or off-site treatment equipment and for how long; how much additional material will be sent to off-site; type and quantity of untreated discharges that enter the environment; final disposition of treatment equipment; daily operating requirements and costs; and the impacts to the current occupants and neighbors.
One sustainable treatment process gaining favor in other states is chemical injection. The chemicals used to destroy or immobilize the contamination through oxidation, reduction, or biodegradation are injected into and around the plume in a series of discrete events. By keeping the remediation in-situ, this method does not transfer the contamination to the air, waterways or landfills or require an aboveground treatment train to separate the contaminates from the extracted vapors and liquids.
No aboveground treatment train means no hard piped system to install and operate, no equipment requiring continuous power to operate, no solid waste from construction or separation processes to send off-site; no site visits to maintain or repair the surface treatment equipment, and no secondary discharge to manage.
Also no aboveground treatment system means current occupants and neighbors do not have to content with noisy motors, lost of space to run a business or an eyesore that can create a public nuisance.
Sustainable remediation such as chemical injection is more than selecting the most efficiency equipment, using clean energy to power the equipment and recycling the equipment when cleanup target levels are reached. It is designing a treatment system that has less impact to the environment and human activity than leaving the contamination in place. It does not transfer the contamination to another location, generate secondary waste streams, and minimizes disruption to the lives of current occupants and adjacent neighbors.
Sustainable remediation strives for zero discharge and impact while removing the contamination from the environment.