Beneficial Re-Use of Biosolids by Agricultural Land Application
What are biosolids?
Municipal wastewater treatment plants in Tulsa separate the liquid
and residual portions of wastewater for processing and treatment.
Biosolids are residuals that have undergone additional treatment
(stabilization) to prepare them for environmentally acceptable
beneficial use or disposal. City of Tulsa biosolids are
stabilized and land applied in an environmentally acceptable manner
in compliance with EPA regulations 40 CFR Part 503.
Is it safe to land apply biosolids?
Land application is the most common use for biosolids. It has been
used for decades and involves spreading the biosolids on the soil
surface or injecting the biosolids into the soil. Biosolids enrich
the soil by providing organic mater and nutrients needed for
crops. Biosolids have been used as a substitute for
commercial fertilizers in the United States for over 50 years.
While there are many opinions about the use of biosolids, most
experts agree that properly applied biosolids will increase crop
production and improve the quality of soil without health risk or
degradation of the surrounding environment.
How do biosolids help the soil and crops?
Biosolids enrich the soil with essential nutrients and organic
matter. Plants need a complex mixture of nutrients, soil, air and
water to grow well. Biosolids contain a full range of essential
plant nutrients that are released slowly, as the plants need them
during the growing season. The organic matter acts as a sponge for
water, nutrients and air where soil organisms can prosper and plant
roots can better develop. This "sponge" also reduces the
possibility of leaching nutrients to the groundwater. The result is
improved crop production, less water runoff, less soil erosion and
more water conservation.
Biosolids Monitoring:
Land applied biosolids meet strict regulations and quality
standards established by the Federal Government Environmental
Protection Agency (EPA) and Oklahoma Department of Environmental
Quality (ODEQ). These rules set numerical limits for metals in
biosolids, pathogen reduction standards, vector attraction
reduction, site restrictions, crop planting and harvesting
restrictions, and monitoring, record keeping and reporting
requirements.
Site Permit & Buffer Zones:
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Each application site must have a permit approved by (ODEQ).
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Buffer zones are set two hundred fifty (250) feet from
residences, any well used for potable water supply or a public
water supply surface water intake; one hundred (100) feet from
waters of the state, including ponds and drainage ditches; and
twenty-five (25) feet from the traveled portion of the public
roadway.
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Buffer zones are set for slopes 5% or greater.
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Harvesting food, feed and fiber crops are restricted for 30 days
after the application of biosolids.
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Animals are restricted from grazing on the land for 30 days
after the application of biosolids.
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Sod grown on land where biosolids is applied shall not be
harvested for one year after the application when the sod is
placed on land with high potential for public exposure.
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Inspections of each application site are made within 18 months
after application to ensure that the site operator is keeping their
obligations.
How are biosolids applied?
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For sites not in the City's land application program, approval
from ODEQ is required to add the site.
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Pre-application site inspections and collection of soil samples
are performed to determine site suitability.
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Application rates are determined based on the crop to be
harvested.
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pH adjustment to soil (if needed) and aeration.
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Application of biosolids
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Incorporation of biosolids into the soil.
Biosolids application is a Partnership with
Landowners
Each project is a partnership between the landowner and the City of
Tulsa for the beneficial and economical application of this
valuable resource. The landowners provide the site and the City
provides the biosolids. Since the City is interested in the most
cost effective sites, landowners that assist in the application
process are more likely to receive biosolids. Assistance may
include hauling of the biosolids from the source, pre-application
aeration, spreading biosolids with a manure type spreader, and/or
post application incorporation. In all cases, the City
provides oversight and record keeping for each project.
To participate in the Biosolids Program, please call or
write:
City of Tulsa, Water Pollution Control
707 South Houston, Suite 505
Tulsa, Oklahoma 74127
(918)-596-9453
