Overview

• Sedimentation and Erosion – What is it?

• Why do we care?

• How to spot serious issues

• Examples and solutions

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Sediment Pollution

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1.3 Soil Erosion

Causes of erosion are:

• Gravity

• Wind

• Water

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Why do we care?

Bull trout in a clear stream • The effects of

sedimentation on aquatic

species and their habitat

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A reduction of light penetration

from suspended sediment:

• limits heat input

• reduces productivity at every level in an

ecosystem

• affects both streams and lakes

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Sediment and fish populations

• Dirt in the water will change fish feeding behavior,

since prey is less visible

• Sediment reduces the abundance of insect larvae and

smothers those that live on the bottom

• The suspended sediment can damage gills

• Effects of several crossings can add up

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Potential impact of sediment on fish habitat

• Fish avoid areas of high sediment – leaving

them with less space to live in

• Loss of spawning habitat

• Loss of insect and plant habitat

• The stream channel gets wider and shallower

as it fills with sediment – then warmer

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Fish Spawning

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SUMMARY

To reduce the impact on fish:

• Allow fish passage through stream crossings

• Prevent erosion

• Keep “deleterious substances” out

• Save streamside vegetation

Why do we care?

Government Regulations!

• Fisheries and Oceans Canada

• Alberta Sustainable Resource Development

• Alberta Environment

• The company who owns the road is

responsible for the crossings

• Large fines

• Poor public image

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How to spot sedimentation issues?

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Gabion baskets used to armour the inflow

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Bridge deck separating from road

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Failed abutment

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Treated wood wingwalls that are failing

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Markers (Y): Good bridge reflectors

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Structural problem (C):

culvert sections have separated

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Structural problem (S): sunken deck

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Structural problem (SL):

slumping caused by gullying under bridge

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When used properly, silt fences are effective in

controlling sedimentation

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1. Preliminary Inspection

Blocked diversion ditch

(requires remedial

measures)

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1. Preliminary Inspection

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False ditch

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Ditch

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3. Sediment Source Inspection

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4. External Sediment Source Inspection

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4. External Sediment Source Inspection

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4. External Sediment Source Inspection

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2006

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2010

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Mud build up on deck

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2006

2011

Preventive Measures

• Armouring exposed soil

• Diverting flowing water

• Road Maintenance

• Monitoring for effectiveness

• Reporting

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Vegetation is considered armour

from an erosion perspective

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Armour – Silt Fence

Armour – Silt Fence

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Armour - vegetation

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Armour – Rip Rap

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Riprap, silt fence and geotextile curb

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When used properly, silt fences are effective in

controlling sedimentation

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Rip Rap Armour

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Slash, Rip Rap and Silt Fencing

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Diversion Ditch - Maintain

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Summary Discussion

What resources do you need to improve the

condition of stream crossings on your

company’s road?

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