Disposal of Biosolids

The disposal of biosolids in the province of Ontario is mandated under the Environmental Protection Act, administered by the Ministry of Environment (MOE). In order to permit the use of biosolids on agricultural lands, the Ministry of Agriculture, Food and Rural Affairs (OMAFRA) contributed in the development of guidelines related to this practice, and how biosolids would affect crop production and soil health. The local Medical Officer of Health of the health unit, while not an integral part of any approval or process involving biosolids use, must still remain informed of such practices as the risk to public health, drinking water supplies or the general environment does exist.
 

In order to implement the structured use of biosolids in the province, the MOE and OMAFRA co-authored the "Guidelines for the Utilization of Biosolids and Other Wastes on Agricultural Lands", March 1996. The Guideline was prepared as a supplement to Ontario Regulation 347, made under the Environmental Protection Act, and was intended to allow for the use of biosolids while:
 

• Protecting the quality of the environment
• Guarding consumer and animal health
• Protecting food quality
• Contributing to the productivity of the land

The Guideline contains criteria, which must be met in order to allow for the disposal of biosolids on agricultural land. The use of biosolids must be of benefit to crop production or soil health, and must not degrade the natural environment. The material (biosolids) must supply essential plant nutrients and/or organic matter that will sustain crop production or soil health. Materials that do not qualify cannot be utilized in this manner. By governing the use of biosolids on agricultural lands, the groundwater and surface water supplies are protected against undue contamination.
 

Waste Management System

In order to operate a biosolids utilization program in the province of Ontario, the operator is required to obtain a Certificate of Approval for a Waste Management System. This approval incorporates all equipment, disposal plots, and assurances related to the project, and reflects the ìlivingî quality of the approval. Changes to processes or equipment or disposal sites can be made to the approval via amendments, and all approvals are obtained through the Environmental Assessment & Approvals Branch of the MOE. A Waste Management System for Biosolid Utilization is not the same as a Waste Management System for Septage Disposal.
 

In order to reflect regional and geographical characteristics, approval of the disposal sites or plots are completed by the Regional Office of the MOE, and Provisional Certificates of Approval reflect such control measures as spreading rates, available sludge quality, native soil conditions, background contaminants, clearance distances to groundwater supplies, bedrock, residential development, or surface water bodies.

To maximize the benefit of biosolid utilization without creating an unnecessary risk to the environment or drinking water supplies, a thorough examination of the sludge is requires. The nutrient component of the biosolid is compared to fertilizer application programs, and undesirable elements such as inorganic wastes, heavy metals, chemical contamination requires stringent monitoring and testing of the sludge source to ensure that the benefit of biosolid use does not create a new environmental concern.

In order to obtain approval for the use of biosolids, the applicant is required to undergo a series of analytical assessments, aimed at protecting the environment, and water supplies. To initiate the approval process, the applicant is required to address the following issues when proposing organic soil conditioning with biosolids:
 

• Plant growth
• Crop quality
• Public and Animal Health
• Quality of the Environment
   

The overall project must not create any condition deemed an environmental risk, not must the practice of biosolid utilization conflict with any other legislation.
 

When assessing the impact of this type of program, the risk of heavy metal accumulation in the environment poses one of the greatest dangers. Specific metals of concern are:
 

• Arsenic 
• Mercury
• Cadmium 
• Molybdenum
• Chromium 
• Nickel
• Cobalt 
• Selenium
• Copper 
• Zinc
• Lead  

By applying wastes with varying levels of heavy metals, the concentration of these compounds in the environment will increase in the soils of the disposal plots. High levels of heavy metals in vegetable crops can introduce these elements to the human food chain, thus transferring the risk of heavy metals, examination of the source (sewage sludge) is required, to monitor the quality of the product, prior to utilization on agricultural lands. Through a series of formulas, ratios of permissible levels of heavy metals to background concentrations (in the soil\) are required, to ensure that the addition of these materials will not increase the contamination of the native soil.

To process the application for the Waste Management System or Organic Soil Conditioning Sites, a thorough review of the disposal sites is required. Under this review, such issues as:
 

• Geographical mapping
• Topographical mapping
• Soils Identification (Soils Mapping)
• Site description - terrain, physiology
• Soil Examination - type, permeability, origin
• Depth to ground water, surface water
• Identification of nearby drinking water supplies, quality & clearance distance
• Clearance distances, residential development

are identified, to ensure that the practice does not jeopardize the environment.

One of the critical items in the review process is the identification of soils in the area. Soil is the framework upon which crops will be cultivated, nourished and harvested, on a long-term basis. Soil also affects the type of crop, which will best flourish. To maximize the benefit of biosolid utilization, the nutrient component of the biosolid must be made available to the plant.

Similarly, in order to protect existing groundwater quality, an in-depth examination of groundwater supplies and quality must be done during the approval process. Identification of any nearby surface water bodies, direction of flow, related to soil type (permeability) and risk of surface water drainage must ensure that the practice does not result in needless contamination of these water supplies. Clearance distances are stipulated under the Guidelines for biosolid utilization plots to drinking water supplies, surface water bodies, and residences. This prescriptive requirement will ensure that a minimum level of protection is afforded across the province for this type of program.
 

Groundwater Protection

In addition to requiring a minimum vertical clearance distance between the application of biosolids on soil, the use of soil in the further treatment of the biosolids aids in the prevention of further degradation of the environment. Soil provides physical, chemical and biological processes, which help minimize the pollution risk of this material. The soil structure helps filter (physical) any organic material, allowing for bacterial (biological) processes, to breakdown any organisms or organic material in the waste. Dependant upon the soil type, chemical reactions and adsorptive (bonding) capabilities of the soil further reduce nutrients such as phosphorous in the waste material.

Public Acceptance

The utilization of biosolids in agricultural applications requires public acceptance of the process, to ensure the viability of the program. Concern over potential pollutants associated with this program, odours, air borne drift (wind carried) or surface water run-off must be addressed at the approval stage, to eliminate any future complaints. Once the public understanding of the benefits of this program are highlighted, the control measures (sampling, testing and monitoring), which are an integral part of the program, will assist in eliminating any concern of nearby residents.

Control Measures

Since the principal benefit of this program is for the diversion of biosolids from landfill sites and utilization of the nutrient by crops/plants, it is important that the program operate in a manner, which will not cause further degradation of the environment. Poor soils, such as dense clays, with poor drainage, or excessive soils, are not acceptable for this type of program.

Waste materials can be applied to mineral soils, but not to organic soils. Organic soils are soils, which already contain 17% or more organic carbon by weight, and have a depth of 0.4 meters or more. Soil pH should be neutral, and background elevations of phosphorus, heavy metals must be known prior to use in this type of program, to ensure that the application of biosolids will not cause further contamination.

To control the risks of an operating biosolids utilization program, control measures are applied to spreading practices. Such controls include restricting the spreading of biosolids on frozen or ice soils, spreading on excessive sloped sites, poor draining soils, and uniform enforcement of clearance distances. Periodic inspections of disposal sites are conducted by staff of the Regional Office of the MOE for verification of control measures.

For sites, which are utilized for crop production, hay or haylage, or vegetable growth, the Guidelines specify spreading restrictions for the various uses. In essence, the practice of biosolid spreading must be suspended:
 

• For hay and haylage: 3 weeks before grazing
• Pasture (horses, cattle): 2 months before grazing
• Commercial Sod: 12 months before harvest
• Vegetables: 12 months before harvest

These time factors will assist in preventing the transmission of pathogenic organisms to humans or animals, and provide a minimum time frame in which the waste material can be treated and absorbed by the soils.

To further minimize the risk of biosolid to public health, care must be taken to proper handling of the material. The Occupational Health and Safety Act provides criteria related to handling practices, and all parties involved in the program must abide by the requirements. Similarly, the responsibility for testing, monitoring and handling of the material relates to all parties. The generator of the waste material must provide quality testing of the material prior to transport, and persons involved in the use of biosolids as part of an organic soil-conditioning program must abide by the criteria of the Guidelines. Failure to meet the testing, sampling and monitoring programs outlined in the Guideline can create a condition which may potentially result in contamination of the environment or more importantly, drinking water supplies.

Where complaints arise from this program, such matters must be addressed by the local office of the MOE, OMAFRA and public health units. Notification to the Medical Officer of Health for matters related to potential contamination of surface or drinking water supplies is necessary to provide a risk assessment, and public notification of any control measures.

Conclusion
 

In closing, the utilization of biosolids for the organic soil conditioning for agricultural use must follow the stringent measures as developed by MOE and OMAFRA. The benefits of utilizing this material in place of landfilling or incineration must reflect the regional characteristics of the area, and the availability of suitable agricultural land.
 

By diverting this material from local landfills, the nutrient component of the waste can be utilized in crop production, and improvement of the overall soil health. Measures aimed at protection of the groundwater or surface water supplies of the area are included by way of sampling and testing prior to use, and on-going monitoring by the operator and the MOE. Sources of biosolids, which do not meet the prescribed quality objectives, are not eligible for this program, and disposal on sites which will not provide the optimum level of treatment and control are similarly eliminated.
 

In order to provide the optimum level of safe guards against unnecessary pollution, the criteria of the Guidelines and MOE regulations must be adhered to. When compared to private on-site sewage systems, which have no maintenance or monitoring enforcement programs, the overall risk of this program is minimal. In producing a cleaner quality effluent for the sewage treatment operations of the urban centers of Ontario, the production of biosolids has increased. The integration of this waste by the agricultural industry would appear to provide an acceptable means for disposal of this waste product.