Difference between revisions of "Build a Berm"
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Berms are raised mounds of earth, usually forming a long ridge. These attractive landscaping features provide more soil depth for planting and help block sound and wind. Mountain bikers build heavy-duty berms to create banked turns. | Berms are raised mounds of earth, usually forming a long ridge. These attractive landscaping features provide more soil depth for planting and help block sound and wind. Mountain bikers build heavy-duty berms to create banked turns. | ||
| − | [[Category:Landscaping and Outdoor Building]] | + | [[Category: Landscaping and Outdoor Building]] |
== Steps == | == Steps == | ||
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#Add the topsoil layer. Spread out a layer of topsoil over the entire berm, mixing it with the top 2–3 inches (5–7.5 cm) of clay.<ref name="rf1" /> Pile on more topsoil to form a layer 1 ft (30 cm) thick. | #Add the topsoil layer. Spread out a layer of topsoil over the entire berm, mixing it with the top 2–3 inches (5–7.5 cm) of clay.<ref name="rf1" /> Pile on more topsoil to form a layer 1 ft (30 cm) thick. | ||
#Compact the soil lightly. Roll an empty lawn roller over the top layer of soil, or tamp it down with your feet or a board.<ref name="rf3" /> The berm will settle over time as water seeps through it, but a light compaction should be enough to minimize erosion. | #Compact the soil lightly. Roll an empty lawn roller over the top layer of soil, or tamp it down with your feet or a board.<ref name="rf3" /> The berm will settle over time as water seeps through it, but a light compaction should be enough to minimize erosion. | ||
| − | #Plant on the surface. [[Get-and-Maintain-a-Healthy-Lawn|Establish a lawn]] over the berm, along with shrubs and trees in a pattern that doesn't interfere with mowing or walking. [[Apply | + | #Plant on the surface. [[Get-and-Maintain-a-Healthy-Lawn|Establish a lawn]] over the berm, along with shrubs and trees in a pattern that doesn't interfere with mowing or walking. [[Apply Mulch|Add mulch]] while the plants are establishing roots to prevent erosion. |
===Building a Berm for Mountain Biking=== | ===Building a Berm for Mountain Biking=== | ||
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#*For your first berm, avoid a sideslope (slope between the two sides of the turn) steeper than a 4:1 gradient (25%). Steeper slopes require a turning platform, which takes a lot more work. | #*For your first berm, avoid a sideslope (slope between the two sides of the turn) steeper than a 4:1 gradient (25%). Steeper slopes require a turning platform, which takes a lot more work. | ||
#Clear all organic material from the area. This includes topsoil, which will decompose and crumble if used on your trail. Build your berm with bare, mineral soil only.<ref name="rf5">https://www.imba.com/blog/morgan-and-steve-lommele/berm-baby-berm</ref> | #Clear all organic material from the area. This includes topsoil, which will decompose and crumble if used on your trail. Build your berm with bare, mineral soil only.<ref name="rf5">https://www.imba.com/blog/morgan-and-steve-lommele/berm-baby-berm</ref> | ||
| − | #[[Build | + | #[[Build a Retaining Wall|Build a retaining wall if necessary]]. Steep berms and berms built onto steep slopes require a retaining wall to prevent collapse. This is a big job, so consider working with experienced builders, or building a berm with a gentle slope instead (10 degrees, for instance). There are two approaches if you decide to go this route: |
#*Flat, square stones weighing at least 50 lbs (23 kg) make the best retaining walls. Lock the stones together with smaller rocks and "deadmen" logs extending into the bank to prevent wobbling, then backfill each layer with small rocks and mineral soil.<ref name="rf4" /> | #*Flat, square stones weighing at least 50 lbs (23 kg) make the best retaining walls. Lock the stones together with smaller rocks and "deadmen" logs extending into the bank to prevent wobbling, then backfill each layer with small rocks and mineral soil.<ref name="rf4" /> | ||
#*Wooden retaining walls take less labor, but rot over time. Use pressure treated wood rated for ground contact ("heavy duty" or "extreme" ground contact in wet climates).<ref name="rf6">http://www.extension.umn.edu/garden/yard-garden/landscaping/selecting-preservative-treated-wood/</ref><ref name="rf7">http://www.awpa.com/standards/U1excerpt.pdf</ref> Lay deadmen logs into the bank, attached to the wall with notched log cabin construction.<ref name="rf4" /> | #*Wooden retaining walls take less labor, but rot over time. Use pressure treated wood rated for ground contact ("heavy duty" or "extreme" ground contact in wet climates).<ref name="rf6">http://www.extension.umn.edu/garden/yard-garden/landscaping/selecting-preservative-treated-wood/</ref><ref name="rf7">http://www.awpa.com/standards/U1excerpt.pdf</ref> Lay deadmen logs into the bank, attached to the wall with notched log cabin construction.<ref name="rf4" /> | ||
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#Perfect the surface. Once your berm has reached the desired height and shape, make the surface as smooth as possible, with a constant slope. Give the berm a test ride and make adjustments until the turn feels smooth. For instance, if the turn feels too abrupt, you may need a wider radius, or a longer lead up into the berm.<ref name="rf5" /> | #Perfect the surface. Once your berm has reached the desired height and shape, make the surface as smooth as possible, with a constant slope. Give the berm a test ride and make adjustments until the turn feels smooth. For instance, if the turn feels too abrupt, you may need a wider radius, or a longer lead up into the berm.<ref name="rf5" /> | ||
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== Tips == | == Tips == | ||
