Figure 18. Installed log revetment with coir geotextile roll combination, Roaring Fork River, Colorado

Figure 17. Schematic of root wad construction

Figure 19. Schematic of log revetment with coir geotextile roll and plantings on top of backfill soil over a geotextile filter

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Appendix B: Bioengineering for Streambank Erosion Control -- Guidelines

Installed log revetment with coir

geotextile roll combination,

Roaring Fork River, Colorado.

Wetland vegetation is seeded or

planted in backfilled soil placed

in a depression between the

revetment and the land. Rock is

placed on top to prevent scour.

Root wads are live or dead logs with root masses attached (Figure 19, see Bowers, Land

and Water, 1992). These are also used in the toe zone to protect it from undercutting, but

must be used in combination with other materials. The fans of the root wads provide an

interlocking wall protecting the streambank from erosion. The voids within and between the

root wads are filled with a soil mix and planted with live, willow clumps or root pads. The

root wads are laid on top of a keyed-in shelf of stone and support logs. This shelf includes

a layer of bottom support logs flush with one another, shingled together, and running parallel

to the streambank. The root mass should be a minimum of 5-ft in diameter and angled slightly

upstream towards stream flow. This treatment should be placed at a base elevation that is

consistent with water levels during the major part of the growing season, i.e., June through

September. The bottom two-thirds of the root wad should be in water during that period of

time. The upstream and downstream ends of the root wad treatment should be tied into hard

points made from rock or some natural hard feature so as to prevent flanking.

Figure 20 shows a treatment using root wads on the Upper Truckee River in California

near South Lake Tahoe, where this treatment and others were monitored for a couple of

growing seasons (see also Volume II). Various local flow velocities were measured along the

treatment on the fall of the hydrograph. These ranged from 1.6 to 4.0 fps at .6 depth of flow

and 4 ft out from the right bank. The root wads sufficiently reduced local flow velocities so

that vegetation had a chance to get established and stabilize the bank despite a

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