Handling Runoff From Solid Agricultural Source Material Storages and Outside Livestock Areas
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IntroductionUncovered manure storage facilities, livestock yards and permanent outdoor confinement areas are exposed to rainfall and snowfall. These liquids and any others, such as urine, that are not absorbed by the manure are called "runoff" when they leave the facilities. This Factsheet discusses runoff components and provides options for Ontario farmers to manage runoff from livestock yards and manure storage facilities in compliance with the Nutrient Management Regulation, O. Reg. 267/03 (the Regulation). Many of the terms used in this Factsheet are defined in Section 1 of the Regulation. Most people recognize runoff as a brown or black liquid. In accordance with the Regulation, it can be described as liquid that:
Runoff from these facilities must be managed to prevent it from flowing over the ground and contaminating surface water as defined in Section 2 of the Regulation or leaching to groundwater where it may degrade water quality. Contamination caused by runoff can be chemical – nitrates and phosphates – and/or biological – bacteria, viruses and parasites. Figure 1. Runoff can be stored in an open-top concrete tank. Farmers who are subject to the Regulation are required to manage their runoff so it does not harm surface water or groundwater. Water quality is also protected under the Ontario Water Resources Act and the Environmental Protection Act. For operations required to have a nutrient management strategy or plan, the Regulation requires that, unless they have a runoff management system (Figure 1) capable of handing all runoff generated by the facility (S.81), no one:
Runoff QualityRunoff may have solid and liquid components. Typically, urine, washwater and contaminated water make up the liquid portion, while the solid portion consists of manure, bedding, feed and soil.
1 Although the long-term effects of nitrates on human health are not known, it is not a good practice to drink water containing nitrates. The recommended maximum acceptable concentration of nitrate as stipulated by Ontario Drinking Water Standards is 10 mg/L. 2 Phosphorus increases algae growth in surface water. When the algae dies and decays in surface water, it uses up oxygen, resulting in potential fish kills. 3 Pathogenic bacteria such as E. coli can cause disease in humans and livestock when they get into drinking water supplies. The constituents in runoff can be broken down into three categories as shown in Table 1. Many of the same contaminants that are found in runoff may also be found in liquid manure. Typically, runoff has a very low solids content (often referred to as dry matter content), resulting in considerably lower constituent levels than liquid manure. Table 2 provides typical constituent levels for runoff and liquid dairy manure. The values show that runoff is a very dilute and lower-risk material as compared to liquid dairy manure. Runoff VolumeSection 81 of the Regulation states that permanent OCAs, permanent
solid nutrient storage facilities and paved livestock yards must
be equipped with a runoff management system that handles all the
runoff generated by the facility. Table 5.2 of the Nutrient
Management Protocol outlines the accepted values for rainfall
effects when estimating the amount of runoff generated by a livestock
yard, OCA or solid storage (Table 3). Current
versions of OMAFRA's NMAN software also use these values and can
be used to estimate the volume of runoff generated by these facilities.
This volume is dependent on the factors outlined in Table
3. * A recognized value in Ontario for liquid dairy manure. In general, runoff volumes from permanent outdoor confinement areas, permanent solid nutrient storage facilities and paved livestock yards are much higher than anticipated by the farmer. For example, a permanent outdoor confinement area can produce up to 36.6 cm (1.2 ft) of depth of runoff per square foot of the outdoor confinement area over a 240-day period. This runoff amount depends on the dry matter content of the manure and manure quantity in the confinement area during this period. A significant percentage of the liquid that falls on a permanent outdoor confinement area, a permanent solid nutrient storage facility or paved livestock yard can be absorbed by solid manure. This absorptive factor has been accounted for in the 0.56 m/year referred to in Table 3. However, when there is a small amount of solid manure in the confinement area, more runoff will result. Reducing Possible RunoffBefore constructing a runoff management system, the amount of possible
runoff can be minimized by directing all clean water away from the
permanent outdoor confinement area, permanent solid nutrient storage
facility or paved livestock yard before it is allowed to come into
contact with manure. Directing clean water away from the facility
will not only reduce the volume of contaminated runoff that has
to be managed, but it will also keep the facility drier, making
it more desirable to work in. Figure 2. An eavestrough system directs clean water away from the outside yard. Surface water moving over the ground from higher elevations may be diverted by installing berms, ditches or other features, while eavestroughs on buildings can direct roof water away from these areas (Figure 2). Runoff Management SystemsIf possible, consider how runoff is to be managed at the planning stage of the manure storage facility, livestock yard or outdoor confinement area. If the facility or area is not covered, provide a small slope (1%–2%) on the floor to one corner to allow the runoff to be collected and managed at one location. A screening system, such as a picket fence, and/or a small settling area at this low point will screen the solids and allow them to settle out. The liquids will drain to the runoff management facility. The Regulation allows for five runoff management systems to be used on farms.
Constructing a roof over a permanent solid nutrient storage facility, permanent outdoor confinement area or paved livestock yard will prevent rain and snow from entering the facility (Figure 3). As long as up-slope water has been diverted, a roofed system reduces runoff volume, since rain and snowmelt do not need to be stored or treated. If precipitation enters the nutrient storage facility, the additional water may also change the dry matter content of the manure, which may change the type of storage system used. Figure 3. Placing a roof over a permanent solid nutrient storage facility eliminates runoff.
Runoff may be collected and stored in a permanent liquid nutrient facility to be spread on cropland as a nutrient source. The storage facility may be constructed of concrete, steel or earth. See Sections 64 to 67 and 71 of the Regulation for the requirement regarding the need to employ a professional engineer or professional geoscientist for siting, design and construction of the storage facility. The initial construction or expansion of a permanent liquid nutrient storage facility must comply with the Regulation. Section 63 of the Regulation stipulates the following siting requirements for runoff containment facilities:
Figure 4. Runoff may be transferred to a vegetated filter strip for treatment. Permanent nutrient storage facilities and livestock housing facilities must be sited to meet municipal bylaw requirements. In most cases, the siting will be calculated based on the Minimum Distance Separation II (MDS II) formula. Contact the municipality about siting prior to applying for a building permit.
A vegetated filter strip system (VFSS) is a runoff treatment system. The Regulation provides design, construction, operation and maintenance criteria for this type of runoff treatment system. If these standards are not met, a Certificate of Approval for a sewage works under the Ontario Water Resources Act must be obtained. A vegetated filter strip system means the complete system required to treat runoff and includes temporary storage, screening and transport of runoff, including a pump, if required, and the vegetated filter strip. The vegetated filter strip, or infiltration area, is a densely vegetated strip of land, engineered and constructed to accept and manage agricultural runoff and washwater by settling, filtration, dilution and absorption of pollutants and infiltration into the soil. Runoff is collected and stored in a settling basin, which could be:
From the settling basin, the runoff either flows by gravity or is pumped to the vegetated filter strip. A perforated distribution pipe is located across the top end of the filter strip to distribute the runoff along the width of the strip (Figure 4). Treatment occurs as runoff moves down the strip. For more information on the design and siting of the vegetated filter strip system, visit www.ontario.ca/omafra. Figure 5. Different flow paths of the same required length.
Other types of treatment systems may be appropriate for farm operations in certain circumstances. The regulation allows for the use of treatment systems other than a VFSS, but these systems must be approved under either Section 53 of the Ontario Water Resources Act or Part 8 of the Building Code. Examples of these other treatment systems could include a septic tank and weeping bed system or a constructed wetland.
A permanently vegetated area can be a permanent pasture, permanent hayfield or forested area that the runoff flows over. The permanently vegetated area is not tiled and must meet all the following criteria:
A permanently vegetated area can only be used as the runoff management system in certain lower risk situations. To use this runoff management option, the manure in the storage facility or paved livestock yard must be at least 30% dry matter. The area where the runoff flows over the permanently vegetated area is referred to as a flow path. The flow path runs through the permanently vegetated area and can be a surface channel or depression that conducts the runoff away from the facility. Treatment occurs as the runoff moves along the length of the flow path. The flow path from the facility to surface water must be a minimum length. The flow path may go directly from the facility to surface water, meander back and forth or be located parallel to a berm along surface water to achieve the minimum length required (Figure 5). Drier manure has less potential for runoff, therefore a shorter length of flow path to surface water is permitted. For larger facilities, multiple flow paths may be required. Further details regarding permanently vegetated areas may be found in Section 81 of Ontario Regulation 267/03, as amended. Facilities Requiring Runoff ManagementUnder Section 81 of the Regulation, permanent outdoor livestock confinement areas, permanent solid nutrient storage facilities and livestock yards paved with concrete or other suitable material require a runoff management system that will handle all the runoff generated by the facility. Permanent Solid Nutrient Storage FacilitiesSection 81(1) of the Regulation requires that a permanent solid nutrient storage facility be equipped with a runoff management system capable of handling all the liquid generated by the facility. Options for Handling Runoff See Table 4.
Paved Livestock Yards Paved livestock yards typically are "exercise" yards where no feeding or watering occurs or where the animals are present for less than 200 days per year. Section 81(2) of the Regulation requires that a livestock yard paved with concrete or other acceptable material, other than a permanent outdoor confinement area, be equipped with a runoff management system capable of handling all the liquid generated by the facility. * All options include a requirement to divert up-slope water away from the facility. ** Where solid manure storage floor area is less than 300 m2. Options for Handling Runoff All options include a requirement of diverting up-slope water away from the facility.
Figure 6. Runoff is generated from permanent outdoor confinement areas. Permanent Outdoor Confinement AreasSection 81(3) of the Regulation requires that a runoff management system be provided for all permanent outdoor confinement areas (Figure 6). The runoff management system must be composed of natural or manufactured runoff collection, treatment and containment devices that are capable of preventing, collecting, treating or containing runoff. Select from the options presented below, keeping in mind that the objective of preventing, collecting, treating or containing runoff must be met. Options for Handling Runoff All options include a requirement of diverting up-slope water away from the facility.
Figure 7. Overview of runoff options for permanent outdoor confinement area, permanent solid nutrient storage facility and paved livestock yard. For more information: Toll Free: 1-877-424-1300 E-mail: ag.info.omafra@ontario.ca | |||||||||||||||||||||||||||
