Contamination is defined as the introduction of any undesirable physical, chemical or microbiological material into a water source. There are two types of contamination sources: point sources and non-point sources. Point sources include landfills, leaking gasoline storage tanks, leaking septic tanks and accidental spills, as the name implies we can point directly to the source of contamination. A point source is technically defined as any discernable, confined and discrete conveyance from which pollutants are or may be discharged.
Non-point sources can be less obvious and can include naturally occurring contaminants such as iron, arsenic and radioloigcals, run-off from parking lots, pesticides and fertilizers that infiltrate the soil making their way into an aquifer. There are numerous regulations that address both point sources and non-point sources of contamination. In addition to these regulations, it is important for citizens to become aware of how their actions can affect the contamination of groundwater and take action to reduce any potential contamination.
The regulations
The Clean Water Act passed in 1972 was enacted to reduce point source pollution. The Act requires a NPDES permit to discharge any pollutant from a point source, specifically industrial facilities and publicly owned treatment works. Before this regulation, many facilities were discharging contaminants direct into our waterways.
This regulation is aimed at protecting surface water, however point sources do not just contaminate surface water they can contaminate ground water. Point Sources that can contaminate groundwater include landfill leachate and leaking underground storage tanks; but these discharges are normally accidental and therefore not regulated.
The Water Quality Act of 1987 set up specific permitting guidelines for storm water discharge. This made industries become more aware of the effect their operations were having on the environment and held them accountable for anything they discharged into the sewer systems.
In 1987, the Clean Water Act was amended to establish the section 319 Non-point Source Management Program. This program allows states, territories and Indian tribes to receive grants to address non-point pollution.
In 1991, the National Monitoring Program was established and supported by the funds authorized under Section 319 of the amended Clean Water Act. The primary objectives of the program include evaluating the effectiveness of watershed technologies designed to control non-point source pollution; and improve our knowledge about non-point source pollution.
Factors that contribute to groundwater contamination
Many factors can affect how groundwater becomes contaminated. The depth of a well is an obvious factor; a contaminant has further to travel in deeper wells. The soil and formations the contaminant travel through acts as a natural filter. The underlying geologic formations also affect the possibility of contamination in two ways.
First, the geological formation can be a source of contamination; there are various rock formations that contain minerals such as calcium, magnesium, iron, arsenic and various radiologicals. While some of the minerals may not cause any known health effects, naturally occurring arsenic and radiologicals are known carcinogens. Second, the formation can slow the contaminant or it may have the opposite affect.
For example, contaminants could travel through sand much quicker than a layer of clay. The amount of rainfall in a given area will contribute to contamination; the more rain that falls, the more water is filtered down to recharge the aquifer. Rainfall that seeps into the ground can carry these contaminants into the aquifer.
The contaminants
There are several properties to consider when looking at contaminants. Some of these properties include: persistence, adsorption, solubility, volatility and molecular size. Persistence refers to the staying power of a contaminant. Certain contaminants do not easily breakdown in the environment, and will persist in the environment for a long time. PCBs are an example of persistence in the environment.
In 1976, the Toxic Substances Control Act (TSCA) prohibited the manufacture and distribution of PCBs, yet they are still found in our environment today. Adsorption refers to how tightly a compound will attach to soil particles. Compounds that are strongly adsorbed are less likely to leach into the groundwater. Solubility is the ability of a substance to dissolve in a solvent. Compounds that are highly water-soluble will dissolve in water percolating through the soils down to the water table. Methyl Tertiary Butyl Ether (MTBE) is an example of a contaminant with a high water solubility, which is one of the reasons MTBE contaminations, is so widespread.
Volatility of a substance refers to its tendency to change from a liquid or solid into a gas. There is a group of contaminants called Volatile Organic Chemicals or VOCs and these compounds readily change from liquid or solid to gas when exposed to the atmosphere. The more volatile a substance is, the more likely it will be lost to the atmosphere.
Lastly, the molecular size can play a role, the smaller the molecule; the more likely it will be able to travel between soil particles.
More regulations for groundwater protection
The Environmental Protection Agency has enacted several programs that are designed to protect our groundwater. These programs include The Safe Drinking Water Act (SDWA), The Resource Conservation and Recovery Act (RCRA), The Comprehensive Environmental Response, Compensation and Liability Act (CERCLA), The Federal Insecticide, Fungicide and Rodenticide Act (FIFRA), The Toxic Substance Control Act (TSCA) and the Clean Water Act. In addition to setting standards for public water supplies, the SDWA regulates underground disposal of waste into deep wells.
The SDWA has also developed a nationwide program for the states to implement wellhead protection programs in an effort to protect groundwater sources. RCRA regulated hazardous waste storage, transportation, treatment and disposal. CERCLA authorizes the government to cleanup contamination sites, which are commonly referred to as Superfund Sites. FIFRA regulates pesticides that have the potential to contaminate groundwater.
TSCA allows the EPA to control the manufacture, use, storage, distribution and disposal of toxic chemicals. The CWA we already discussed, aid in the development of programs to protect water sources. This includes public education; consumers need to become aware that anything they dump into the sink or down a drain will influence water quality.
Private well protection
The first step in protecting a private well is proper placement of the well. Many states and counties may have regulations regarding placement of wells. For example, they may require the well to be so many feet away from sources of contamination such as septic systems, animal feedlots and underground storage tanks. The well should also be placed in an area where the ground slopes away from the well so surface water will not collect around the wellhead.
Once the well is drilled, it is the homeowner's responsibility to protect the water source. All hazardous materials should be stored far away from the well. The National Ground Water Association suggests that homeowners maintain a clean zone of 50 feet around the wellhead. This means no pesticides, herbicides, paints or gasoline should be used or stored within the clean zone. Testing is recommended anytime the well is serviced or if there is a noticeable change in the water's taste, odor or appearance because this could indicate a change in the water quality. In addition, testing should be done on a regular basis to establish a baseline of the water quality; this will be helpful in determining if the water quality is being degraded.
Homeowners should also have an annual check-up performed by a professional well contractor to uncover any problems with the well construction. Proper maintenance and protection of well systems will provide the homeowner with many years of a quality water source.
Groundwater is an important source of drinking water for our nation. Steps must be taken to protect this invaluable resource. Since the 1970's, significant progress has been made in regulating our activities to reduce the possibility of contaminating groundwater sources. It is important that everyone understands exactly what impact we can have on the quality of groundwater and take preventative measure to reduce groundwater contamination.
