Conditions where practice applies

Filtrexx™ Silt Soxx™ are to be used in any area requiring sediment or erosion control where runoff is in the form of sheet flow or in areas that silt fence is normally considered acceptable. For the purposes of this document, Filtrexx™ Silt Soxx™ and silt fence are considered approved equals. The use of Filtrexx™ Silt Soxx™ apply to areas of high sheet erosion, on steep slopes up to and exceeding a 2:1 slope, and in other disturbed areas of construction sites requiring sediment control. Filtrexx™ Silt Soxx™ may also be used in sensitive environmental areas, where migration of aquatic life, including turtles, salamanders and other aquatic life is impeded by the use of silt fence.

Planning Considerations

Filtrexx™ Silt Soxx™ control erosion by trapping sediment and slowing water that filters through the Filtrexx™ Silt Soxx™. This will create temporary ponding during heavy rains. On slopes, compost protects round soil particles from gaining momentum and creating erosion because compost is flat and does not roll like soil. It is possible to drive over Filtrexx™ Silt Soxx™ during construction, but these areas should be immediately repaired by manually moving back into place, if disturbed. Continued heavy construction traffic will reduce the effectiveness of the Soxx.

Design Criteria for Filtrexx™ SiltSoxx™:

The sedimentation removal process associated with Silt Soxx™ involves both filtering and deposition from settling. This is different than other methods using only ponding for deposition of sediment. Ponding occurs when water flowing to the Silt Soxx™ accumulates faster than it can flow through the Soxx. Typically, Soxx can handle the same water flow or slightly more than silt fence. However, installation technique is especially important for them to work effectively.

For most applications, standard silt fence is replaced with 12”{30mm} Silt Soxx™

Level Contour:

Place Silt Soxx™ on level contours to assist in dissipating flow into sheet flow rather than concentrated flows. Do not construct Soxx that concentrate runoff or channel water. Sheet flow of water should be perpendicular to the Silt Soxx™ at impact and relatively un-concentrated.

Flat Slopes:

When possible, place Silt Soxx™ at a 5’ {1.5m} or greater distance away from the toe of the slopes in order for the water coming from the slopes to maximize space available for sediment deposit (see cad drawings attached). When this 5’{1.5m} distance is not available due to construction restrictions, a second Silt Soxx™ may be required (see drainage area chart below).

Flow around ends:

In order to prevent water flowing around the ends of Silt Soxx™, the ends of the Silt Soxx™ must be constructed pointing upslope so the ends are at a higher elevation.

Vegetation:

For permanent areas, seeded Silt Soxx™ allow vegetation to be established directly in the Soxx and immediately in front and back of the Soxx at a distance of 5 {1.5m} feet. Vegetation on and around the Silt Soxx™ will assist in slowing down water for filtration. The option of adding vegetation will be at the discretion of the Engineer. No other soil amendments or fertilizer are required for vegetation establishment.

Drainage area:

Filtrexx™ Silt Soxx™ - Maximum Drainage Area Based on Slope and Slope Length Slope Length (linear feet) Silt Soxx™ Required Slope {linear meters} (Height x width) 0%-2% Flatter than 50:1 250 ft. {76.2m} 12 inch{30cm} Diameter 2%-10% 50:1-10:1 125 ft. {38.1m} 12 inch{30cm} Diameter 10%-20% 10:1-5:1 100 ft. {30.48m} 12 inch{30cm} Diameter 20%-33% 3:1-2:1 50 ft. {15.24m} 18 inch{45cm} Diameter >50% >2:1 25 ft. {7.62m} 18 inch{45cm} Diameter

Dispersing flow:

Sheet flow and runoff should not exceed height of berm capacity in most storm events. If overflow of the berm is a possibility, larger Soxx should be constructed, or other possible sediment control tools may be used. Alternatively, a second berm may be constructed or used in combination with compost blankets to prevent sediment from moving.

Maintenance Requirements:

Filtrexx™ Silt Soxx™ should be regularly inspected to make sure they hold their shape and are producing adequate flow through. If ponding becomes excessive, Soxx should be dispersed and reconstructed. For purposes of longer-term sediment control objectives, Soxx can be seeded at the time of installation to create an additional vegetative filtering component.

When construction is completed on site, the Soxx may be dispersed with a loader, rake, bulldozer or other device to be incorporated in the soil or left on top of the soil for final seeding to occur. The mesh netting material will be disposed of in normal trash container or removed by the Contractor.

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