BIOSOLIDS
DISPOSAL
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 ělivingî 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:
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.
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