Some might wonder why storage walls are needed. Horse manure stacks well naturally because of the bedding in it, with side slopes about 30° — a 3-m vertical rise to a 5-m horizontal spread.
However, runoff occurs from the sloped sides of the piles, whereas walls make the manure stack deeper, reducing runoff, as the walls force rainfall to soak into the pile. All things being equal, for two piles of manure with equal volume and height, one with walls requires less floor area than one without walls (Figure 8).
A pile without walls is difficult to shape to exactly fit a rectangular-shaped concrete pad — the most practical shape of pad to construct because of forming issues.
Table 2, on page 6, compares piles with equal volumes and heights in storage with and without walls. The storage without walls assumes the pile is shaped like a cone stored on a square floor. Both storages extend 15 cm (6 in.) beyond the pile to help keep manure on the pad. Walls give something to push against, save cleanout time and help retain heat to promote composting.
Figure 8. The pile without walls has more floor, uses almost as much concrete and has more exposed side surface area producing runoff.
The material used to construct the walls is a matter of choice, function, longevity and cost. Reinforced concrete (Figure 9) is durable and will withstand the abuse of weather, manure juices and pushing from the manure and equipment.
Figure 9. This 3 m x 6 m x 1 m high (10 ft x 20 ft x 3.25 ft) horse manure storage has reinforced concrete walls, making it easy to push against with a loader.
Concrete blocks (Figure 10) are inexpensive but do not fit perfectly together and are difficult to manoeuvre. Wood walls (Figure 2) must be designed to withstand manure pressures and be made of pressure-treated wood.
Floor versus no floor?
It is easier to load and unload manure storages when there is a good concrete floor underneath. However, under the right conditions, an expensive permanent concrete floor just might not be necessary.
Farms covered under the Nutrient Management Act (2002) constructing solid manures storages must use one of three types of floors:
- concrete (or equivalent)
- earth floor, 0.5 m (20 in.) of hydraulically secure soil
- earth floor, 0.5 m (20 in.) of hydrologic soil Type C or D soil, as long as the farm is <300 NU in size
The hydrologic soil type is based upon a soil’s rate of water intake after prolonged wetting. Type C soils are typically clay loam, while Type D soils are clay.
These soils are far less likely to allow seepage to percolate through the soil from the manure. Many horse farms in Ontario have this type of soil and are candidates for storages without a concrete floor.
However, when handling manure on soil floors, take care that the floor does not get badly rutted. Where soil floors are permitted, an innovative way to provide some rutting protection is to install rubber matting (Figure 11).
Roof versus no roof?
Horse manure storages don’t need roofs, as the manure is dry, and there is little runoff. Roofed storages (Figure 12) likely need building permits
Figure 10. The 0.6 m x 1.2 m x 1.2 m (2 ft x 4 ft x 4 ft) concrete blocks used to build a storage for compost material at this landscaping firm are perfect for building a horse manure storage.
Building Your Storage
To build manure storage for 10 horses like the one in Figure 5 and Figure 9, with three walls, 1 m (3.25 ft) high, open to the front, with a flat concrete floor, you will likely need a building permit. This will phase you under the regulations of the Nutrient Management Act, so your storage will have to hold at least 240 days worth of manure.
Solid manure storage volumes are usually calculated as the product of storage length, width and height. However, this does not work for small storages, as there is considerable loss of storage volume at the open front because of the manure slope.
Also, it is more difficult to store manure very deep as it can spill out over the walls when nearly full. Table 3 shows dimensions of a few small manure storages that satisfy the 240-day required storage period.
Figure 11. Used conveyor belting from a quarry operation was used as a floor to protect the soil from rutting under this landscape compost pile.
Another requirement under the NMA is to provide a permanently vegetated flow path to contain and treat any minimal runoff that might result from the pile.
The flow path is the distance over the ground that liquids have to flow from the storage before entering surface water or tile inlets. This does not have to be in a straight line. Figure 5 shows a meandering flow path.
A permanently vegetated flow path has a saucer shape and a healthy stand of vegetation to slow down any runoff from the storage and use up its nutrients. The NMA specifies the length of flow path based on manure dry matter content.
For horse manure 30% to <50% dry matter, use a 150-m (492-ft) flow path; for horse manure 50% or greater dry matter, use a 50-m (165-ft) flow path. Most horse manure is 30%–50% dry matter.
The flow path must be located on a minimum of 0.5 m (20 in.) of soil, no closer than:
- 3 m (10 ft) from a field tile drain
- 15 m (50 ft) from a drilled well
- 100 m (328 ft) from a municipal well
- 30 m (100 ft) from any other wells
Table 3. Dimensions and volumes stored assuming 1.0-m (3.25-ft) walls and pile shape as in Figure 5.
(Note: It may be difficult to store manure deep using wheelbarrows.)
Minimum Distance Separation (MDS) Formula
The Minimum Distance Separation (MDS) II Formula determines minimum setbacks between new or expanded livestock facilities (such as horse barns or manure storages) and existing or approved development next door (such as a neighbouring house). MDS II is triggered when a building permit is required and the calculation of setbacks is done by the municipality. For more information, consult your Municipal Office.
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