methods of sediment control steve pudenz agc/ndor partners in construction

Methods Of Sediment ControlMethods Of Sediment ControlSteve PudenzSteve Pudenz

AGCAGC/NDOR/NDORPartners in ConstructionPartners in Construction

Properly installed silt fence is a very effective Properly installed silt fence is a very effective temporary sediment control device temporary sediment control device

100 ft. of silt fence can retain 180 tons of sediment.


Goal of Silt FenceGoal of Silt Fence

• Detain water for sedimentation to occur.Detain water for sedimentation to occur.

• Occasionally used to divert stormwater Occasionally used to divert stormwater to a storage area.to a storage area.

• Retain large soil particles and prevent Retain large soil particles and prevent loss from the site.loss from the site.


Each link must work; if one link fails, Each link must work; if one link fails, the system failsthe system fails

PlacementPlacement

QuantityQuantity

InstallationInstallation

CompactionCompaction AttachmentAttachment

SupportSupport

Effective silt fence works like a chain…Effective silt fence works like a chain…


CorrectCorrect IncorrectIncorrect

• Refers to specific location on each construction site.Refers to specific location on each construction site.• Specific design (layout) at each locationSpecific design (layout) at each location.

PlacementPlacement


Designs calledDesigns called

J-hooks insureJ-hooks insure

water & sedimentwater & sediment

pond behindpond behind

each silt fence.each silt fence.

J-hooksJ-hooks


Proper Silt Fence PlacementProper Silt Fence Placement


Proper PlacementProper Placement

• Should pond water Should pond water

• Stop sediment before it reaches the Stop sediment before it reaches the pavementpavement

• Withstand concentrated flowsWithstand concentrated flows

• Should insure sedimentationShould insure sedimentation


The ends must always be long enoughThe ends must always be long enoughto pond water and sediment.to pond water and sediment.

Incorrect Silt Fence PlacementIncorrect Silt Fence Placement


Myth – flat sites do not need protectionMyth – flat sites do not need protection


Leave room for sediment storage at toe of slopeLeave room for sediment storage at toe of slope


DO NOTDO NOT use silt fence: use silt fence:

• Where you can not create a storage area for runoffWhere you can not create a storage area for runoffExamples:Examples: Steep slopes, small areas, or short Steep slopes, small areas, or shortsegmentssegments

• Where you can not prevent water running around Where you can not prevent water running around the endthe end

• In a V-shaped or shallow channelIn a V-shaped or shallow channel


On-site adjustment is On-site adjustment is MANDATORY!MANDATORY!

• Grading plans are often drawn in an office Grading plans are often drawn in an office many months prior to disturbance.many months prior to disturbance.

• The ESC contractor must adjust the plan to The ESC contractor must adjust the plan to properly control the site, or at a minimum properly control the site, or at a minimum notify the site managers of potential notify the site managers of potential problems.problems.


Relates to area of control. Relates to area of control.

The volume of water from a large site The volume of water from a large site can not be controlled in one run of silt can not be controlled in one run of silt fence.fence.

Multiple locations or storage areas are Multiple locations or storage areas are often required.often required.

QUANTITYQUANTITY


• Long runs should be avoided.Long runs should be avoided. They tend to accumulate sediment in one They tend to accumulate sediment in one area, causing premature overflow.area, causing premature overflow.


Breaking up a run more than doubles storage areaBreaking up a run more than doubles storage area


Multiple runs slow runoff velocity Multiple runs slow runoff velocity and add storage area on site.and add storage area on site.


Proper QuantityProper Quantity

100 ft. of silt fence per 10,000 sq. ft100 ft. of silt fence per 10,000 sq. ft of disturbed area seems to be an adequate of disturbed area seems to be an adequate

rule of thumb for sediment controlrule of thumb for sediment control


Relates to how the fabric is placed in the Relates to how the fabric is placed in the soil, appropriate depth of placement, and soil, appropriate depth of placement, and

appropriate backfill for an effective silt fenceappropriate backfill for an effective silt fence.



Two Methods of InstallationTwo Methods of Installation

• TrenchingTrenching

• Mechanical/SlicingMechanical/Slicing


Mechanical InstallationMechanical Installation


Mechanical InstallationMechanical Installation

• Provides consistent, dependable silt fenceProvides consistent, dependable silt fence

• Reduces many labor related installation Reduces many labor related installation problemsproblems

• Disturbs but does not excavate soil which Disturbs but does not excavate soil which creates an optimal condition for creates an optimal condition for compactioncompaction


Improper installation often leaves silt fence Improper installation often leaves silt fence blowing in the wind.blowing in the wind.


• Relates to soil permeability. Loose or Relates to soil permeability. Loose or trash-filled backfill is easily saturated with trash-filled backfill is easily saturated with water and washed out under the silt fence. water and washed out under the silt fence.

• Compacted soil resists saturation, and Compacted soil resists saturation, and prevents washouts. prevents washouts.


CompactionCompaction

Example of Poor CompactionExample of Poor Compaction


Relates to a support system that will not fall Relates to a support system that will not fall over under the load of a full silt fence.over under the load of a full silt fence.

SupportSupport


Support Post SpacingSupport Post Spacing

Posts should be Posts should be

5 ½ ft. tall5 ½ ft. tall

and spaced a and spaced a

maximum of 6 ft. apart. maximum of 6 ft. apart.

60" steel

30” min.aboveground


Properly supported silt fence will carry Properly supported silt fence will carry 24 inches of sediment.24 inches of sediment.


Proper attachment Proper attachment

is the glue of the system,is the glue of the system,

combing the strength of the fabric and the combing the strength of the fabric and the support posts into a unified structure. support posts into a unified structure.


AttachmentAttachment

AttachmentAttachment

Steel postsSteel posts - recommend 3 plastic ties per - recommend 3 plastic ties per

post, located in the top 8 inches of the post, located in the top 8 inches of the

fabric, placed diagonally to attach as many fabric, placed diagonally to attach as many

threads as possible.threads as possible.

Wood postsWood posts - recommend several staples - recommend several staples

per postper post


Attachment must be adequate to Attachment must be adequate to support a fully loaded silt fencesupport a fully loaded silt fence


Maintenance & InspectionMaintenance & Inspection

• Key to successful silt fenceKey to successful silt fence

• Inspect weekly and after every ½” rain event or Inspect weekly and after every ½” rain event or as neededas needed

• Clean out when over half full or install a new silt Clean out when over half full or install a new silt fence above or below the current fencefence above or below the current fence


NDOR Silt Fence

Low Porosity Low Porosity

High PorosityHigh Porosity

Coir FenceCoir Fence


Low Porosity Silt Fence

• Most CommonMost Common

• Used to contain sedimentUsed to contain sediment

• Used for perimeter controlUsed for perimeter control

• 42” Tall is NDOR standard42” Tall is NDOR standard

• Low Profile is 36” tall used in urban areas Low Profile is 36” tall used in urban areas and medians and medians


High Porosity Silt Fence

• Used across ditchesUsed across ditches

• Used to slow the flow of waterUsed to slow the flow of water

• Not to be used for perimeter control Not to be used for perimeter control


Coir Silt Fence

• Environmentally sensitive areasEnvironmentally sensitive areas

• 100% degradable material100% degradable material

• 36” tall36” tall


Each link must work; if one link fails, the system failsEach link must work; if one link fails, the system fails

PlacementPlacement

QuantityQuantity


CompactionCompaction AttachmentAttachment

SupportSupport


Effective silt fence works like a chain…Effective silt fence works like a chain…

Overall, the key is Overall, the key is changing behaviors.changing behaviors.


methods of sediment control steve pudenz agc/ndor partners in construction

Documents

effective silt fence

run of silt fence

sediment storage

dependable silt fencereduces

tons of sediment

large site

area of control

storage areas