Deactivation

Question 1

Some important water management principles

Answer 1

• Never combine several watercourses into one ditch or channel
• Always work from upslope to downslope
• Do not create slope instability by over- steepening cut and fill slopes
• Avoid disturbing sensitive soils
• maintain water quality
• Do not introduce debris or soil into watercourses
• Keep water flows wide and shallow to reduce erosive energy

Question 2

Where is most road deactivation done?

Answer 2

High risk roads only to save money, but ultimately land owner decides.

Question 3

Formula for risk

Answer 3

Likelihood of hazard X consequence

Question 4

What is the biggest cause of erosion in roads?

Answer 4

Mass wasting.

Rule of thumb is to treat slopes above 60% hillside with extreme caution. Soil types and surficial indicators are other important considerations.

Question 5

What’s causes surface erosion?

Answer 5

poor direction of water. Lack of ditches. Use during wet weather.

Question 6

What are some values effected by road failures, erosion and sedimentation.

Answer 6

Social and Economic Values:

• Life (high consequence)
• Property – railways, highways, roads, utilities, landscape, recreation
• Water supply
• Landscape, recreation values

– Resource Values:

• Habitat (Fish or Wildlife)
• Forest land
• Non-forested land

Question 7

What is the main goal of reconnaissance terrain stability mapping?

Answer 7

Usually designed to cover areas of mostly stable topography, having some potential unstable areas.

Does not include consequence ratings

Question 8

What is detailed terrain stability mapping?

Answer 8

Detailed Terrain Stability Mapping

– polygon labels include:

• slope gradient
• soil drainage
• symbols are used to identify features that are too small to be mapped (small landslide, gully, terrace scarp)
• bedrock geology is sometimes included

Question 9

What do cracks on road indicate?

Answer 9

The potential of imminent failure

Question 10

What are road deactivation objectives

Answer 10

• maintain or re-establish natural hill slope drainage patterns;
• minimize the potential for road-related landslides and erosion;
• Re-establish slope angles to be stable;
• enhance productive growing sites, where practical;
• minimize maintenance for inactive roads;
• Decrease the cost to reactivate when needed;
• minimize impact on the environment;

Question 11

3 levels of deactivation

Answer 11

1. Temporary

– Use of road is temporally suspended for 3 years and harvesting is until next rotation

3. Permanent

– When the road is not needed ever again

Question 12

When would u do a permanent deactivation?

Answer 12

If the area is going to slide

Question 13

What are some considerations for temporary deactivation

Answer 13

• If road is to be left unmaintained
• Decide what kind of access you need

– 2wd, 4wd, ATV, Mountain Bike, Hiking Trail

• Remove grader windrows on outer edge of road surface
• Drain road surface by crowning, in-sloping, out-sloping
• In areas of steep terrain or heavy rainfall

– Build water bars and cross ditches

– May require removal of drainage structures

• Inspect after major storms
• Will still require some regular maintenance

Question 14

What size stone should you armor with?

Answer 14

D50 size material

Question 15

Where do you armor, mulch and plant to stabilize soil

Answer 15

– Culvert outfalls

– Bridge abutments

– Sidecast near stream banks

– Cross ditches

– Anywhere there is an appreciable amount of running water

Question 16

What are some typical seed mixtures for stabilization

Answer 16

• Usually a mixture of grasses and legumes
• Sometimes alder seed is added
• 15 – 30 kg / ha. for dry seeding
• 80 kg / ha. for hydroseeding
• Do it in spring or fall and allow 5 – 6 weeks for germination