Methods Of Sediment Control Steve Pudenz AGC/NDOR Partners in Construction

Properly installed silt fence is a very effective temporary sediment control device 100 ft. of silt fence can retain 180 tons of sediment. AGC/NDOR Partners in Construction

Goal of Silt Fence Detain water for sedimentation to occur.Detain water for sedimentation to occur. Occasionally used to divert stormwater to a storage area.Occasionally used to divert stormwater to a storage area. Retain large soil particles and prevent loss from the site.Retain large soil particles and prevent loss from the site. AGC/NDOR Partners in Construction

Each link must work; if one link fails, the system fails Placement Quantity Installation Compaction Attachment Support Effective silt fence works like a chain… AGC/NDOR Partners in Construction

CorrectIncorrect 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. Placement AGC/NDOR Partners in Construction

Designs called J-hooks insure water & sediment pond behind each silt fence. J-hooks AGC/NDOR Partners in Construction

Proper Silt Fence Placement AGC/NDOR Partners in Construction

Proper Placement Should pond waterShould pond water Stop sediment before it reaches the pavementStop sediment before it reaches the pavement Withstand concentrated flowsWithstand concentrated flows Should insure sedimentationShould insure sedimentation AGC/NDOR Partners in Construction

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

Incorrect Silt Fence Placement AGC/NDOR Partners in Construction

Myth – flat sites do not need protection AGC/NDOR Partners in Construction

Leave room for sediment storage at toe of slope AGC/NDOR Partners in Construction

DO NOT use silt fence: Where you can not create a storage area for runoff Examples: Steep slopes, small areas, or short segmentsWhere you can not create a storage area for runoff Examples: Steep slopes, small areas, or short segments Where you can not prevent water running around the endWhere you can not prevent water running around the end In a V-shaped or shallow channelIn a V-shaped or shallow channel AGC/NDOR Partners in Construction

On-site adjustment is MANDATORY! Grading plans are often drawn in an office many months prior to disturbance.Grading plans are often drawn in an office many months prior to disturbance. The ESC contractor must adjust the plan to properly control the site, or at a minimum notify the site managers of potential problems.The ESC contractor must adjust the plan to properly control the site, or at a minimum notify the site managers of potential problems. AGC/NDOR Partners in Construction

Relates to area of control. The volume of water from a large site can not be controlled in one run of silt fence. Multiple locations or storage areas are often required. QUANTITY AGC/NDOR Partners in Construction

Long runs should be avoided. They tend to accumulate sediment in one area, causing premature overflow.Long runs should be avoided. They tend to accumulate sediment in one area, causing premature overflow. AGC/NDOR Partners in Construction

Breaking up a run more than doubles storage area AGC/NDOR Partners in Construction

Multiple runs slow runoff velocity and add storage area on site. AGC/NDOR Partners in Construction

Proper Quantity 100 ft. of silt fence per 10,000 sq. ft of disturbed area seems to be an adequate rule of thumb for sediment control of disturbed area seems to be an adequate rule of thumb for sediment control AGC/NDOR Partners in Construction

Relates to how the fabric is placed in the soil, appropriate depth of placement, and appropriate backfill for an effective silt fence Relates to how the fabric is placed in the soil, appropriate depth of placement, and appropriate backfill for an effective silt fence. Installation AGC/NDOR Partners in Construction

Two Methods of Installation TrenchingTrenching Mechanical/SlicingMechanical/Slicing AGC/NDOR Partners in Construction

Mechanical Installation AGC/NDOR Partners in Construction

Mechanical Installation Provides consistent, dependable silt fenceProvides consistent, dependable silt fence Reduces many labor related installation problemsReduces many labor related installation problems Disturbs but does not excavate soil which creates an optimal condition for compactionDisturbs but does not excavate soil which creates an optimal condition for compaction AGC/NDOR Partners in Construction

Improper installation often leaves silt fence blowing in the wind. AGC/NDOR Partners in Construction

Relates to soil permeability. Loose or trash-filled backfill is easily saturated with water and washed out under the silt fence.Relates to soil permeability. Loose or trash-filled backfill is easily saturated with water and washed out under the silt fence. Compacted soil resists saturation, and prevents washouts.Compacted soil resists saturation, and prevents washouts. AGC/NDOR Partners in Construction Compaction

Example of Poor Compaction AGC/NDOR Partners in Construction

Relates to a support system that will not fall over under the load of a full silt fence. Support AGC/NDOR Partners in Construction

Support Post Spacing Posts should be 5 ½ ft. tall and spaced a maximum of 6 ft. apart. AGC/NDOR Partners in Construction

Properly supported silt fence will carry 24 inches of sediment. AGC/NDOR Partners in Construction

Proper attachment is the glue of the system, combing the strength of the fabric and the support posts into a unified structure. AGC/NDOR Partners in Construction Attachment

Attachment Steel posts - recommend 3 plastic ties per post, located in the top 8 inches of the fabric, placed diagonally to attach as many threads as possible. Wood posts - recommend several staples per post AGC/NDOR Partners in Construction

Attachment must be adequate to support a fully loaded silt fence AGC/NDOR Partners in Construction

Maintenance & Inspection Key to successful silt fenceKey to successful silt fence Inspect weekly and after every ½” rain event or as neededInspect weekly and after every ½” rain event or as needed Clean out when over half full or install a new silt fence above or below the current fenceClean out when over half full or install a new silt fence above or below the current fence AGC/NDOR Partners in Construction

NDOR Silt Fence Low Porosity High Porosity Coir Fence AGC/NDOR Partners in Construction

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 and mediansLow Profile is 36” tall used in urban areas and medians AGC/NDOR Partners in Construction

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 controlNot to be used for perimeter control AGC/NDOR Partners in Construction

Coir Silt Fence Environmentally sensitive areasEnvironmentally sensitive areas 100% degradable material100% degradable material 36” tall36” tall AGC/NDOR Partners in Construction

Each link must work; if one link fails, the system fails Placement Quantity Installation Compaction Attachment Support AGC/NDOR Partners in Construction Effective silt fence works like a chain…

Overall, the key is changing behaviors. AGC/NDOR Partners in Construction