Old Route 99 Road to Trail Sediment Reduction Project

Activities Summary

Trash collected during the Old 99 Spring Clean-A-Thon

During the course of this project, we removed the Old Highway 99 roadbed and reconstructed a 10’ wide trail with a 2’ vegetated shoulder on either side. The trail has a 1% outslope, which minimizes concentrated runoff, and encourages sheet flow. Near the bottom of the hill, the shoulders increase in width. This portion of Highway 99 had been abandoned and unmaintained for over 60 years. The impervious pavement concentrated runoff, which was exacerbated by parking lots and roads in the upper reaches of the Old Highway 99 canyon sub-watershed. Another problem with the abandoned road was vehicle access, which allowed dumping, and the canyon required a considerable amount of trash-cleanup work (This trash clean-up was done as a part of the Redding 2002 Clean-A-Thon; during this event, over 60 volunteers, several trucks and a backhoe donated by Shasta College pulled over 11,000 pounds of trash out of the project site). During the course of this project, we also removed the right descending levee bank to allow the creek to access its floodplain.

On Old 99, the impervious blacktop was removed and the road was recontoured, improving the drainage. The City of Redding will later pave the recreational trail, and add amenities, such as benches, water fountains, and poles at either end to prevent automobile access. The upper 300’ of the trail was installed to connect the trail to the sidewalk on the west side of Market Street. This trail was constructed by cutting a ledge in the slope, and supporting it with a Mechanically Reinforced Earth (MRE) wall. The MRE wall consists of wire grids surrounding layers of earth, with brushlayers in between. Upslope of the wall, a Keystone wall was installed to support the new cutslope.

Road Removal

This project provided an excellent opportunity to demonstrate slope recontouring and restoring hillslope hydrology and landform. Our operators used a hydraulic excavator and bulldozer to reshape the road to an out-sloped trail. Removed fill was recycled and used to fill in the old cutslope, approximating the historic landform. Outsloping the trail maintains natural hydrologic flow by minimizing both concentration of runoff, and subsequent gully formation. These measures will reduce flooding and stabilize the watershed from erosion.

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After

Fuels Reduction

Hand crews and a tracked chipper were used to demonstrate one technique of fuels reduction. The heavily vegetated areas immediately above the trail were cleared to reduce fire potential, and subsequently seeded with native grasses to encourage establishment of native plant communities, as opposed to weed invasion.

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Beltline Road

The Beltline access road on the ridge overlooking the project was one of our primary concerns in this project. The road had been concentrating drainage for a long distance, and causing a large gully. We fixed this by outsloping the road slightly, and installing waterbars at regular intervals to break up the water flow. All disturbed areas were seeded and mulched.

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The steep dirt road that provided access to the Beltline road was also outsloped, and a few waterbars were installed as well, due to the steepness of the road (see below).

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Waterbar on newly outsloped road

Gully Remediation

2 major gullies were treated during the course of this project. The first, identified on the Site map as (XX), was regraded by laying the slope back, and filled with riprap. All exposed soil was then seeded and mulched.

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The second gully, formed by concentrated runoff coming off the Beltline road, also had the edges laid back, and a live pole drain was installed down the center by Shasta College students to help drain any remaining flow, and to anchor the soil with willow roots. After the live pole drain was installed, the remaining swale was brushlayered to further stabilize the soil and encourage revegetation.

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