IMEG’s civil engineering expertise was instrumental in a $1.2 million repair of the Sycamore Canyon Park Trail, a 2.7-mile hiking loop near Diamond Bar, CA.

Major winter storms in January 2017 had rendered access unsafe, forcing the trail to close due to substantial erosion and slope failure at the upper drainage terrace of the trail system, undermining two of the four tiers of stairway leading to the trail. This was the third slope failure since the inception of the site slope and drainage system in 1984. IMEG’s civil engineers were tasked with determining the best course of action to prevent a similar event from happening again.

IMEG provided an existing topographic survey, hydrology and hydraulic analysis of the existing and proposed conditions, along with site design, assistance with FEMA funding, and construction administration services. The proposed slope repair included reinforcement to the 1-1/2 to 1 (horizontal to vertical) fill slope with geogrid layers. The proposed storm drain system included modifications to the existing terrace drains and terrace storm drain inlets to provide sufficient capacity to effectively intercept storm water flow and convey it safely into the existing storm drain system.

The proposed storm drainage system also included essential emergency overflow down drains, should the storm drain inlet(s) fail due to lack of maintenance or other unforeseen situations.
A block interception wall directs the flow down a drain system that ultimately delivers it to the upper terrace and upper terrace drains.

After a delay due to FEMA approval, construction began in the spring of 2019 and completed with a ribbon-cutting ceremony reopening the trailhead Nov. 5, 2019.

For more information on the project, including before-and-after photos and video, visit the City of Diamond Bar website. https://www.diamondbarca.gov/801/Sycamore-Canyon-Park-Slope-Erosion-Repai