Stevens-Rugg Brook: Diversion Structure Improvement Alternatives St Albans, Vermont

Background Flood damage to homes, businesses, rec areas, and ag areas led to need for detention structure between Stevens and Rugg Brooks Water quality, sediment and erosion concerns Three proposed initial routes: railroad, power line, trailer park

Many problems existed between the city and landowners leading to the selection and implementation of the power line alternative construction began on structure Stevens Brook diverts water to Rugg Brook

Detention Structure Map of Jewett Brook and Mill River Watersheds Two streams are Stevens (N) and Rugg (S) City of St Albans in orange/teal

Problem The existing St. Albans diversion structure is not effective at preventing floods during high water flow events and does not produce effluent that meets water quality standards.

Stevens Brook and existing Culvert Culvert holds 70 cfs when full Base flow is 2 cfs When flow exceeds 70 cfs, pooling occurs which leads to diversion structure

Diversion Structure: Sediment Basin

Diversion Structure: Outlet weir

Diversion Structure: Outlet

Diversion Structure: Rugg Brook

Problem: Sedimentation

Problem: Debris Accumulation

Problem: Water Quality

Problem: Erosion-Stevens

Improvement Measures: 1 Construct Sediment Traps in Existing Basin Excavate permanent deep pools for sediment revegetation for aquatic habitat Removal of pollutants bound to sediments

Measure 1: Engineer Drawing

Improvement Measures: 2 Construct Detention Basin by Excavating Diversion Channel Excavate 2-3 ft deep basin at downstream end Low flow outlet in existing weir Sediment forebay at head of basin Revege for aquatic habitat

Improvement Measures: 3 Construct Detention Basin by Raising Outlet Structure Low flow outlet at current elevation, raise weir 1-2 feet Sediment forebay at head of basin Revege for aquatic habitat

Improvement Measures: 4 Construct Enhanced Wetland in Diversion Channel Enhance habitat Sinuous low flow channel for settling Shallow and deep pools Sediment forebay Revegetation for aquatic habitat

Alternative Constructed Wetlands Flood attenuation Pollutant removal Aquatic habitat Extended detention wetland Pond/wetland system Pocket wetland

Findings: Multiple Criteria Decision Analysis

From MCDA most important criteria are: pollutant removal, flood water detention and stream geomorphology Pollutant Removal Flood Water Detention Geomorphology of Rugg Brook Total Measure Measure Measure Measure 43014

Recommendations: MCDA Measure 2: sediment forebay and detention pond Constructed wetland close to outlet including native plant stock Reduction and development of effective impervious surfaces in the city of St Albans. Riparian buffers

Recommendations: Buffer Stevens Brook Bank stability Reduce sedimentation

Buffer Along sides of detention pond and constructed wetland Increase bank stability Habitat Aesthetics

Recommendations: Monitoring and Maintenance Are the improvements functioning as designed? Future sediment removal and disposal Testing effluent against water quality standards Geomorphologic assessment of Rugg

Acknowledgments Erica Gaddis Breck Bowden Dan Lindly: Town administrator Bonnie Wagner: Northwest Regional planning Commission