County of Monterey River Road Emergency Project

In February 2021, Monterey County and much of the Central Coast were hit with an atmospheric rain event. This alongside the River Fire from August 2020 resulted in debris flow from the Santa Lucia Mountains, home to 6,400 acres of grape vines, rushing down into the creeks that feed the Salinas River. The County selected Harris to help support repairs at one of the most significant disaster sites: River Road and Fairview Road.

Core Elements

River Road runs parallel to the Salinas River and includes culverts to convey runoff from the creeks coming down the mountain range. Unfortunately, the debris flow plugged several culverts causing runoff to flow over the road and erode the downstream side of the creeks. Under leadership from Harris’ Vice President of Engineering, Frank Lopez, our team of Civil Design and Environmental Planning + Compliance professionals led the charge of:

• Replacing the existing 48” CMP culvert with two 48” HDPE culverts
• Repairing the upstream and downstream slopes within the existing channel
• Improving portions of River Road in compliance with County standards (including drainage facilities to capture and convey roadway runoff)
• Providing environmental compliance and permitting services to support both the emergency actions and permanent project (including CEQA, biological resources, and cultural resources)

One of the most significant challenges with this project was the channel elevations in such a short stretch. The Harris design team had to find ways to slow the water down to avoid degradation of the proposed pipe and erosion of the channel bottom. One solution was to encase the pipe in concrete to provide redundancy should the velocities erode the proposed pipe. The concrete encasement served a dual purpose which also allowed embedment of the dual pipes into the existing ground to avoid lateral movement. Additional redundancy measures included the design of energy dissipating structures and materials within the channel and two 24-inch standpipes at the upstream end of the channel. These measures mitigate the erosive nature of the channel and account for potential overtopping of River Road should large debris runoff into the channel.

The impact to the farmers and surrounding community could’ve been disastrous since the road closure blocked local land-owners from accessing their properties and businesses. The team held a meeting with the County Supervisor, local farmers, wineries, and land-owners to get input, communicate about the project, and coordinate solutions. The contractor was scheduled to close the road for a one-month period with a detour of 12 miles. Because of the collaboration of the County staff, contractor, and Harris Team, the contractor completed the road closure in two weeks. This reduced impacts to local businesses significantly.

Beyond the Blueprints

Experience, expertise, and relationships account for much of the success of this project. This is the fourth emergency project that the Harris Team has partnered with the County. This experience collaborating with the County under these circumstances, as well as the regulatory agencies, leads to alignment of expectations and trust.