Materials Storage and Handling

Materials Storage

A wide variety of materials, both solids and liquids are temporarily stored on the ground. Examples include stockpiles of raw materials, chemicals and waste at industrial sites; piles of raw materials at construction sites; stockpiles of chemicals, manure, agricultural products and empty containers in agricultural and industrial areas; and stockpiles of salt for road de-icing (Wis. Admin. Code Trans. 277 regulates storage of highway rock salt piles). Materials are kept in the open or in enclosures such as tanks or sheds. Many of these materials are hazardous, even toxic. If the stored material or waste is water soluble, it will leach out when exposed to rain and infiltrate the soil, which may lead to groundwater pollution.

Chemical Storage Tanks

Storage and transmission of a wide variety of fuels and chemicals is inherent in many industrial and commercial activities. Petroleum products are the most common potential pollutants stored in tanks. Throughout Wisconsin, underground storage tanks installed during the 1950s and 1960s have reached or exceeded their life expectancy of 20 to 30 years. Some tanks leak, polluting groundwater, because they were not made of the corrosion-resistant materials required today. Leaks in buried tanks and pipelines at industrial facilities are a particular problem because they can go undetected for some time. Gasoline is less dense than water and tends to "float" on top of the groundwater. It may penetrate basements and sewers, creating a fire hazard or causing explosions, and may contaminate wells and springs, rendering drinking water unsafe.

The large volume and high concentration of hazardous materials that can be released in a small area from a storage tank creates a high on-site pollution risk. These leaks are not usually detected until a large amount of the chemical has been released. Water supply wells near leaking storage tanks may become contaminated.

Industry sources estimate the average cost of "simple" tank cleanup is $70,000 (Knopp). If cleanup operations entail removing and disposing of the leaking tanks and surrounding soil, installing pumping wells and subsequently treating the contaminated water, the cleanup cost can become astronomical.

Spills of Hazardous Materials

Waste is considered hazardous if it has the potential to cause or contribute to an increase in mortality or irreversible illness, or if it poses a threat to human health and the environment (Chapter NR 700 series, Wis. Admin. Code). Hazardous wastes are produced in many segments of society including hospitals, research facilities, industries and government agencies. Industry is by far the largest generator of hazardous waste. Common hazardous contaminants include volatile organic compounds (VOCs), hydrocarbons, pesticides, pesticide production residues and heavy metals. In the past the U.S. Environmental Protection Agency estimated that 90 percent of hazardous materials are disposed of unsafely, leading to groundwater problems.

About 1,400 accidental or intentional spills of hazardous materials were reported in Wisconsin in 1994. An unknown number of additional spills and illegal dumpings go unreported. Statewide, petroleum products are the pollutants most commonly involved in spills. Spills can occur anywhere at any time: on or off site, on highways, runways, waterways or railroads. Most spills are small and can be quickly cleaned up before much of the substance reaches groundwater. Unfortunately, in many cases, the first people on the scene of a hazardous spill are not trained to properly deal with the situation. All spills should be immediately reported to WDNR (1-800-943-0003) or the local emergency government office.

The number of hazardous spills indicates existing preventive controls are not working to the degree necessary to protect groundwater. There is a high risk to nearby wells if the spills are not quickly and adequately cleaned up. Once groundwater is contaminated, remedial actions to clean up the problem can be very costly. Because remedial technology is limited, some spills cannot be adequately cleaned up at all; any contaminated wells are then abandoned and bottled water is used until new wells are constructed. The risk of groundwater pollution can be minimized through better management of all facilities and equipment used for storing hazardous materials, more careful transport of these materials, improved training of people working with these materials, and immediate response and containment of spills by trained individuals.

Metallic and Nonmetallic Mining

Mining of nonmetallic materials and metallic minerals can impair groundwater quantity and quality. Gravel pit or mine operation typically involves lowering the water table for materials extraction. Removing topsoil and other materials reduces the area's ability to attenuate contaminants, while the operation of heavy equipment and illegal waste disposal increases the likelihood of a release. Shallow groundwater flow changes can also occur in these situations.

Nonmetallic mining includes sand and gravel operations and crushed rock quarries. WDNR is developing rules regarding these operations.

Metallic mining is regulated in five distinct parts:

1. exploration--searching for minerals by drilling is regulated under NR 130;
2. prospecting--collection of bulk samples for analysis is regulated under NR 131;
3. mining--the extraction of the minerals is under NR 132;
4. waste disposal-- management of materials and process wastes is regulated under NR 182;
5. and finally the long-term liability of mining companies is established in Stats. 107.30 - 107.35.

Several deposits have been discovered within the basin.

Storage And Use Of Salt For Road De-icing

Salt storage, road salting and snow dumping are all commonly used to de-ice roads and improve winter driving conditions. These activities may result in high salt concentrations in both surface and groundwater. Sodium chloride and calcium chloride are the salts most often used. Sand is readily available, is relatively easy to store and handle, is non-toxic and is the least expensive de-icing material commercially available (Wis. DOT).

Leaving salt piles uncovered allows rain to dissolve the salt, which may then seep into shallow aquifers. Road salt storage is regulated by Wis. Admin. Code Trans. 277, which requires storage on an impermeable surface and in a covered container that prevents contact with water. Storage sites should be located in areas that have deep impermeable soils with a low water table and should be designed to reduce surface water runoff and minimize infiltration of salt to groundwater.

Snow removal piles can also threaten groundwater. Snow removed from streets is often contaminated with salt, oil, heavy metals and toxic substances. Proper siting of these piles is important to protecting both surface and groundwater. WDNR has developed guidance on selecting sites for snow disposal. A pamphlet, Where to go with the snow (PUBL-WR-154-95REV), and assistance on locating suitable sites is available from the WDNR Bureau of Watershed Management.

For more information on groundwater, visit the WDNR - Drinking Water and Groundwater Program