McFarland Creek Erosion Repair

Residents within the project area complained for years about erosion in their back yard along McFarland Creek. Wessler first assessed the drainage and erosion issues because of a drainage complaint by a resident whose backyard is bordered by McFarland Creek. As a result of the complaints and identification of a collapsed culvert, a study was completed to analyze alternatives and determine a cost-effective solution.

The selected alternative included improvements to the collapsed culvert pipe and detention pond upstream of the residential properties that controls the flow of water entering McFarland Creek. Significant erosion repair work along McFarland Creek was also needed. The collapsed culvert under the access road was redirecting the flow around the culvert and over the access road creating natural gullies, erosion of the banks, and undermining the access road. The restriction at the collapsed culvert caused uncontrolled, high velocity flows to impact the banks downstream. As a result, there were multiple areas where exposed soil was present, and erosion was actively occurring along the banks.

Regrading of the banks and vegetated armoring was designed and implemented downstream along McFarland Creek to keep the slope stable when the creek water level is high. This vegetated bank will help prevent slope erosion and provide stabilization. Having deep-rooted vegetation on the slope armors the soil and anchors it.

Two box culverts in parallel were designed to replace the collapsed culvert. It was determined that in order to reduce velocities and control the stormwater runoff generated in the drainage area upstream, a 9X3 and 9X4 box culvert was required. The larger box was set at the same elevation as the existing culvert pipe out of the pond to maintain the retention volume. As stormwater volume and flow increases, the second box, set a foot above the pond outlet elevation, is utilized to convey the larger storm events.

Overall, the project provided the control needed at the culvert and detention basin and erosion repair and protection downstream to minimize the impact of the flows through McFarland Creek.