Weber River High Flow Diversion Channel

Overview

Figure 1. 2011 Sluffing of Gravel Pit

In South Weber, the Weber River lays 70 ft from the rim of Staker Parson’s gravel pit. Throughout the year, average flow rates for the river are around 200-300 cubic feet per second (cfs). During a high runoff season in June of 2011, the river experienced flows up to 4,920 cfs for a week.

During this time, seepage and erosion were observed on the north slopes of the gravel pit (see Figure 1). The high flow velocity and depth was assumed to be the cause of the seepage. River-bank failure analysis shows, the gravel pit would fill, then water would flow into South Weber City causing significant damage. Figure 2 shows a model of the flood path through the city.

Figure 2. Flood Model Based on 2011 River Flowrate

Alternatives

1) Alternative Flow Channels

Source: Reno Mats

2) Lined Riverbed

Source: Performance Footing

3) Berm and Diversion Channel

Source: Canada Water Portal

4) Cutoff Walls

Source: Schnabel Engineering

Selected Alternative and Design

Figure 3. Selected Alternative and Design Plan

The preferred design prevents erosion by lowering river depth and velocity through a high-flow diversion channel (Figure 3). The channel reroutes one-third of peak flows downstream, bypassing previous erosion sites. In addition, the repaired berm keeps the main and diversion flows separated as water levels rise (Figure 4).

Figure 4. Berm Cross-Section Detail

Figure 5. Channel Cross-Section Detail

Figure 6. Gabion Basket - Source: Phi Group

The channel utilizes gabion baskets for sidewalls and a gabion mattress for the channel bottom (see Figure 5). Gabions are wire mesh containers that hold imported rock and prevent erosion along the channel (see Figure 6). They are simple to install and cost effective.

Selection Process

Evaluation criteria ordered by importance:

Weber River: July 2025

• Safety
• Cost to City
• Environmental Impacts
• Permitting Ease
• Maintainability
• Risk to Staker Parson Pit
• Other Economic Impacts
• Social and Cultural Effects

Criteria weights prioritized South Weber’s safety and cost-effectiveness.

Since complete bank failure is not certain, budget was initially weighted more heavily than environmental or social impacts, resulting in selection of the high flow diversion channel. After presenting to the city council, it was determined that available funding sources make project cost a lower priority than previously assumed.

Acknowledgements

Our team would like to give a special thanks to

• Austin Ball S.E., P.E. - Senior Design Professor
• Brady Cox P.E., PhD - Geotechnical Advisor
• Brandon Jones P.E. - Jones & Associates, City Engineer
• Colin Phillips PhD - Hydraulic & Sedimentation Advisor
• South Weber City Council