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Portland Parks & Recreation plans to close this section of the Springwater Corridor south of the Ross Island Bridge soon to repair erosion. The project is expected to take a month,.

(Margaret Haberman/The Oregonian)

Bike commuters, runners and walkers beware: A section on the busy Springwater Corridor will close during the day starting at the end of the month so workers can repair a pesky spot

.

The slide area is about a mile south of the Ross Island Bridge between mileposts 1.5 and 1.75 -- right in the middle of a stretch that has no quick turnaround.

The city of Portland is making a nod toward trail users by keeping the section open before 9 a.m. and after 4 p.m. on weekdays. But from 9 a.m. to 4 p.m. Monday through Friday, it'll be closed. As in, no public access: You'll have to back track if you come upon the construction.

(Take heart, though: The section will be open at all hours on weekends, but still be careful around the site.)

The city plans to announce the exact closure date soon. The work -- costing $650,000 -- is expected to last through October.

The erosion began in March 2012 after hard and prolonged rain and high river water combined to eat away the hillside,

officials say. When the asphalt path cracked, crews put up cones, sandbags and plastic sheeting, keeping one lane open.

The repairs will stabilize the slope and rebuild the trail. The plan calls for using anchors to secure soil wrapped by natural fibers to the slope and then planting natural vegetation -- native grasses and groundcovers, willows, snowberry, oceanspray and mock orange.

The anchors are giant nails driven at an angle about 20 feet into the soil by an excavator using an arm that will extend over the slope, says parks spokesman Mark Ross.

The city has hired

as the contractor. Metro and the city are splitting the project costs.

A second repair phase is unscheduled and unfunded at this point, parks officials say. It calls for driving vertical wooden piles into the river bottom to hold logs and root wad supports in place, using a mix boulders and wood for reinforcement and planting vegetation at the bottom of the bank for more support.

-- Margaret Haberman