Virginia Biosolids Council | Health and Safety

SITE RESTRICTIONS
& BUFFERS

Long-term scientific studies have consistently demonstrated that biosolids recycling through land application is safe.

The management of biosolids to minimize environmental and health risks has been the focus of hundreds of university research studies conducted for many years. The results of this extensive research show that biosolids can be land applied without harm to the environment or to human health.

To ensure that biosolids are treated and appropriately managed, the U.S. Congress directed the Environmental Protection Agency (EPA) to develop comprehensive national standards to reduce the risks and maximize the benefits of land application of biosolids. In February 1993, following the most comprehensive risk assessment in the history of the agency, EPA issued its biosolids use and disposal regulation, 40 CFR Part 503, commonly referred to as the Part 503 Rule.

In Virginia, the General Assembly has enacted numerous laws to regulate the production and beneficial use of biosolids, based on the Part 503 Rule. The EPA has approved Virginia’s biosolids management program and the Virginia Department of Environmental Quality (DEQ) has the primary responsibility for regulating the land application of biosolids in the Commonwealth.

Biosolids regulations address the following:

Trace elements
Biosolids contain small amounts of heavy metals, or “trace elements,” as do natural soils, manures and commercial fertilizers. These trace elements come from human wastes, household plumbing systems, household products, businesses and industries. The EPA thoroughly studied the potential risks from these trace elements and set strict maximum levels in biosolids to ensure protection of public health and the environment. Because of required industrial pretreatment and the risk-based standards for biosolids recycling, the risks posed by trace elements in biosolids are minimal.

Many of the regulated elements in biosolids are beneficial in correct amounts. Chromium, copper, iron, manganese, selenium, and zinc are micronutrients for plants, animals and humans (look at the contents of a multi-vitamin tablet). It is the presence of these micronutrients that accounts for the greater effectiveness of biosolids as fertilizer when compared to traditional chemical fertilizers. However, if the concentration of these elements were to get too high, they could be harmful to people, plants or animals. There are several steps taken to prevent this from happening.

Government limits: In order to protect human health and the environment, the EPA set limits on the amount of trace elements allowed in biosolids. These levels are based on more than 20 years of research and scientific risk assessments of how trace elements affect soils, plants and animals.

Pretreatment requirements: Rigorous pretreatment programs control the amount of pollutants entering wastewater treatment plants. Laws regulate industries to make sure that they dispose of their pollutants safely. This means that pollutants are removed from the waste stream before they ever reach the sewer. This ensures that biosolids contain only small quantities that EPA has determined to pose no risk.

Testing & Monitoring: Biosolids are routinely tested by the wastewater treatment plants and the biosolids applicators to make sure that they comply with all regulatory requirements.

Pathogens
Before treatment, wastewater may contain disease-causing microscopic organisms, such as bacteria and viruses, which are known as pathogens, or germs.

Federal law requires treatment to reduce pathogens: Digesters and other forms of treatment kill from 90 to 99.5 percent of the pathogens originally found in wastewater solids, which allow biosolids to be safely applied to agricultural and forest lands. Additional treatment by heating and/or composting can create a product that is used in home gardens and landscapes.

The environmental cleaning process: After land application, natural environmental conditions such as exposure to sunlight, lack of moisture and a relatively harsh soil environment destroy nearly all of the few remaining pathogens that may exist in biosolids.

Bioaerosols
Because you can usually smell biosolids being applied on a farm, some people have wondered whether disease-causing organisms left over from the wastewater treatment process could be spread through the air to humans or animals. There have even been unsubstantiated allegations of illness after land application.

However, there are no scientifically documented cases of illnesses caused by biosolids. There have been a number of scientific studies that demonstrate the difficulty of transmitting biosolids-related diseases through the air. Current federal and state regulations, combined with the implementation of land application best management practices, make it even more unlikely that diseases can be transmitted from biosolids.

Nitrogen
Biosolids contain organic and inorganic nitrogen and can be applied to plants as a fertilizer to dramatically accelerate growth. However, the addition of too much nitrogen, whether from biosolids or from a commercial fertilizer, can leach or runoff and pollute groundwater or surface water.

Sites receiving biosolids applications are carefully selected and managed to ensure the protection of water resources. Farmers and foresters consider plant needs and soil nutrient levels when applying biosolids to their crops and trees and adhere to buffer restrictions to protect waterways and wells. Biosolids nitrogen is released slowly as soil microbes convert organic nitrogen into plant available inorganic nitrogen. This process, along with adherence to buffers, helps protect the Chesapeake Bay from nutrient runoff. In contrast, buffers are not required for chemical fertilizers, which are highly soluble and can run off into receiving waters.

SITE RESTRICTIONS
Virginia has established site-specific biosolids management practices that go above and beyond the EPA’s Part 503 Rule. These include:

Agronomic rate application (fertilizer application that matches the crop needs) only once every three years, or annually only at less than agronomic rates. These practices control the buildup of soil phosphorus and residual nitrogen.
Soil pH requirements based on regional soil types.
No application to slopes over 15 percent and specified best management practices (BMPs) and restrictions on applications to slopes over five percent.
Additional restrictions on winter operations.

Site physical characteristics that influence the land application of biosolids include:

Topography
Geology (limestone or other fractured bedrock beneath the surface)
The ability of soil to absorb water and drainage patterns
Depth of the soil to groundwater
Soil conditions (rocky, shallow or saturated)
Proximity to ponds, lakes, rivers and streams
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BUFFERS
Buffers set minimum distances between the biosolids application site and streams, wells, dwellings, roads and property lines. While all biosolids must meet federal and state standards for safety, the requirements for buffers provide an extra layer of protection to prevent negative environmental impacts, minimize public exposure and reduce potential nuisances. Buffers do the following:

Keep biosolids applications on the permitted site
Control runoff or leaching from the applied area
Protect surface water and other non-targeted areas
Reduce off-site odors

The requirements for buffers are defined by the DEQ and are listed in the accompanying table.

Click to enlarge chart

Property and dwelling buffers may be increased or decreased, depending on specific site considerations. For example, buffer distances to property lines and dwellings can be reduced if the farmer’s neighbors agree to sign a waiver. Buffer requirements can be increased by VDH at specific sites to address unusual conditions or to reduce impacts on adjacent neighbors.

The boundaries of buffer areas must be clearly marked with flags prior to land application and land appliers must ensure that biosolids are not spread in these areas.

Why is there concern about biosolids?

While the preponderance of scientific evidence and practical experience supports the safety of biosolids, there are still people who are convinced that the land application biosolids should be prohibited. How can there be such a difference of opinion?

One of the obvious reasons is that biosolids have a very high “yuck” factor. Biosolids are, after all, a by-product of the wastewater treatment process, which processes the waste from our toilets so that clean water can be returned to our waterways. When applied to farmland, biosolids can have an unpleasant odor. Some people cannot reconcile these factors with assurances from scientists and regulators that the material is safe and beneficial.

Another factor is the application of the “precautionary principle,” which, simply stated, says that unless you can prove something is “safe” you should not use it. “Better safe than sorry,” they would caution. The problem with this rigid approach is that nothing can be proven 100 percent safe. There is always the possibility that a product can be misused or that future scientific research will reveal new information.

Life in today’s modern world would be impossible if we rigidly applied the "precautionary principle" to every new technology or even to technologies that are commonplace. Automobiles kill thousands of people every year, some pharmaceuticals have adverse effects, people die from electrocution or gas leaks—the list could go on and on.

Most of us, perhaps unconsciously, accept these risks because of the benefits they bring and the harmful consequences of doing without them. We understand that we must rely on the preponderance of scientific research, best available technology and appropriate government regulation to minimize the risks of modern life so that we can continue to make progress.

Compared to other risks in our society, the health or safety risks from biosolids are so small as to be almost non-existent. Despite the claims of some opponents, there are no scientifically documented cases of adverse health effects caused by biosolids. Research has shown that the thousands of people who work at wastewater treatment plants or who land apply biosolids daily do not suffer more health problems than the general population. Ongoing scientific research continues to demonstrate that biosolids are safe and beneficial.