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Chapter 7

Nonfarm Erosion Control

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Introduction

• Soil is also disturbed by home building, industrial expansion, urban construction, highway construction, and many other nonfarm activities

• Daily, as many as 8,000 acres of U.S. farmland are converted to nonfarm use

Cont.

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Introduction

• Millions of acres of land are disturbed annually by strip mining for coal and other resources

• As new highways are constructed and old ones are widened, moved, or repaired, millions of miles of road banks are subject to water-caused erosion

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Controlling Nonfarm Erosion

CAUSES

• Construction• Drainage ways drastically

changed• Concrete or asphalt• Runoff problem severe• Sedimentation or gullying • Expensive control practices

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Mechanical Erosion Controls

DIVERSION DITCHES OR BERMS

• Collects the runoff• Typically earth structures• Runoff to an outlet• Ditch is dug out of the ground• Berm is mounded

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WATERWAYS

• Collect excess soil water• Rock-lined or concrete-lined• Conducted away quickly• Slope is very steep• Steep diversion waterway• Water chute

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SEDIMENT BASIN

• Like a small pond• Designed to be filled up• Catches excess runoff• Sediment settles• Temporary structures• Used during construction

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BANK PROTECTION

• Extra efforts to stabilize banks• Seed, mulch or hydroseeding• Concrete or stone walls• Jute matting• Wooden strips placed

across the slope• Chemical binding

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TERRACING

• Solution on long, steep banks• Breaks into shorter slopes

• Disposal areas• Grassed or lined waterway• Chute• Wooded area• Storm sewer

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DOWNSTREAM RUNOFF

• Very large construction projects• Large factories• Normal stream flow may be greatly

increased• Flooding• Measures may be needed downstream

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Vegetative Erosion Controls

LAWN

• Most common technique• Nonfarm sites• Seedbed• Sprigging• Plugging• Sodding

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SOD

• Quick development• Heavy growth of grass• Squares or strips• Living layer• Produced on a sod farm• Soil must be well prepared

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MULCH

• Holds grass seed in place• Maintains surface moisture• Protects from erosion• Silage-like slurry• Chemical bonding

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GROUND COVERS

• Low-growing shrubs, • Vines, or other plants • Used much like grass• Combined with mulching• Increase protection

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TEMPORARY COVER CROPS

• Construction sites• Protect an area temporarily• Construction delays• Many plants can only start at certain times

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Highway Erosion Control

SPECIAL PROBLEMS

• Highway surfaces• Practically waterproof• As level as practical

• Exposed banks• Erosion damage• Sediment

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Strip Mining Operations

PROBLEMS

• Large increase• Appalachia• Very steep slopes• High-velocity water

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Strip Mining Operations

VIRGINIA COAL MINES

• Spoil• Drainage and erosion-control system• Two-year period• Land must be reclaimed• Bond is forfeited with noncompliance

• Government regulations to be followed

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Summary

• The impact of falling raindrops must be absorbed by something other than the soil surface, and the speed of the runoff must be kept under control

• Because almost all construction disturbs and reshapes the land, it exposes the soil to greatly accelerated erosion

Cont.

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Summary

• Mining operations and highway construction present the same or even more extreme problems of erosion

• The best solution to the erosion problem is almost always a combination of both vegetative and mechanical measures

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