Old Route 99 Road to Trail Sediment Reduction Project

Erosion Control and Revegetation

Erosion Control

The erosion control (surface erosion) concerns were focused on cut and fill slopes, equipment traffic ways and staging areas, and disturbed channel banks. Erosion control for soil surface stabilization focused on preventing raindrop and sheet erosion while re establishing native grass communities. Seed and mulch was applied to all disturbed areas prior to storms.

Exported Channel Material

Spoil areas were graded to slopes less than 2:1, recontoured and revegetated with native grasses. The fill sites below the shopping center parking lot were seeded and mulched and planted with native trees and shrubs during the Old 99 Volunteer Planting Day.

Streambank Revegetation and Erosion Control near Stream Restoration Areas

All channel realignment, construction and instream restoration activities will be performed between July 1, 2002 and October 15, 2002 while the stream is dry. In most years, Hwy 99 Creek does not begin to flow until November. All instream restoration activities involving heavy equipment will be completed by October 15, 2002. During a previous restoration project on Sulphur Creek, Shasta College and SWAG used a water truck to “wash” the channel at the end of construction. Any fines brought to the channel surface by the heavy equipment operations were washed back into the interstitial spaces between the gravel and cobbles. This technique successfully mitigated for any downstream sedimentation during the first winter storms (first flush).
The biotechnical structures being installed for this project are designed to simultaneously reestablish riparian vegetation and control bank erosion as a single treatment entity. Cut and fill slopes will be treated with surface erosion control (seeded and mulched with native grasses). Disturbed areas along the stream bank above bankfull elevation that are not receiving biotechnical structures will also be treated with surface erosion control.

Seeding

The seed mix was as follows:

Sediment Pond

A sediment pond with silt fence baffles was constructed at the mouth of Hwy 99 Creek, and contained all sediment that was produced during construction of the project. The sediment pond has been planted with wetland species, and once all construction is complete in the project area, the baffles will be removed, ad the area will be allowed to function as a wetland.

Revegetation

The main revegetation components of this project were incorporated into the biotechnical structures, the planting of various wetland, riparian and upland species that occurred during the Volunteer Planting Day, and the erosion control / disturbed soil treatments. The biotechnical structures include pole planting, brushlayering and live pole drains with willow and cottonwood species. All other disturbed soil will be seeded with native grasses for the combined goals of erosion control and ecological restoration.