Sennebec Dam Removal St. George River ... - SLIDEBLAST.COM
Sennebec Dam Removal St. George River Restoration
Sennebec Pond
Dam
Sennebec Pond
Dam
River Profile
Engineering Evaluation
Engineer’s Role in Project • • • • •
Technical input for options analysis Facilitate evaluation and selection Design for dam removal and rock ramp fishway Permit Application Construction Management
Tabulation of Alternatives Assessment Rehabilitation Safety Risk Fish Lake Option Passage Level/Hydraulic Control No Action Medium to No Not long term low Rehab Dam Medium to No Yes low Dam Rehab w/ Medium to Yes Yes Fish Passage low Intermediate Low Yes Yes
Cost
Operation & Maintenance
$108,000 None $185,000 High $533,000 High to Very High $513,000 Medium
Dam Relocation Upstream Dam Relocation
Low
Yes
Yes
$234,000 Low
River and Lake Access Not long term No Change No Change Moderate Loss Most Loss
Aesthetics
No change No change Minor change Relic remains w/ new dam Relic remains w/ river-like view
New River Profile
Rock Ramp Profile
Pond Level • Picture of turtle rock
Computer Model • • • • •
HEC-RAS Setting parameters for weir Determining flow velocities Determine riprap/stone sizes Assuring fish passage under design flows
Rock Ramp Design • Used examples from Germany and Australia • Consulted with experts including Laura Wildman, American Rivers, Dr. Luther Aadland, U.of MN, ACOE • Prepared a conceptual design for permitting • Final design meeting with stakeholders
Breach Existing Dam & Restore Site • Cut Down East Abutment for Access • Remove West Abutment and Spillway • Step Back Remaining East Abutment and Plug Canal Gate • Use Fill to Reshape Slopes Around Dam • Conserve Historic Elements of Dam
Permitting/Approval Process • State/Federal: NRPA, Wetlands Alteration, SHPO, Incidental Taking Permit, • Town: Shoreland, Site Development, Demolition • Pre-application discussions with regulators • Stakeholder review/comments on drafts • Public outreach
Construction • Competitively Bid • H. E. Sargent, Inc. Stillwater, Maine • Early fall - low water conditions • Full time on-site oversight by TU volunteer PE • ME DMR represented fishery agencies • Completed on budget and ahead of schedule
Low flow channel pic
Sennebec Pond
Dam
Sennebec Pond
Dam
River Profile
Engineering Evaluation
Engineer’s Role in Project • • • • •
Technical input for options analysis Facilitate evaluation and selection Design for dam removal and rock ramp fishway Permit Application Construction Management
Tabulation of Alternatives Assessment Rehabilitation Safety Risk Fish Lake Option Passage Level/Hydraulic Control No Action Medium to No Not long term low Rehab Dam Medium to No Yes low Dam Rehab w/ Medium to Yes Yes Fish Passage low Intermediate Low Yes Yes
Cost
Operation & Maintenance
$108,000 None $185,000 High $533,000 High to Very High $513,000 Medium
Dam Relocation Upstream Dam Relocation
Low
Yes
Yes
$234,000 Low
River and Lake Access Not long term No Change No Change Moderate Loss Most Loss
Aesthetics
No change No change Minor change Relic remains w/ new dam Relic remains w/ river-like view
New River Profile
Rock Ramp Profile
Pond Level • Picture of turtle rock
Computer Model • • • • •
HEC-RAS Setting parameters for weir Determining flow velocities Determine riprap/stone sizes Assuring fish passage under design flows
Rock Ramp Design • Used examples from Germany and Australia • Consulted with experts including Laura Wildman, American Rivers, Dr. Luther Aadland, U.of MN, ACOE • Prepared a conceptual design for permitting • Final design meeting with stakeholders
Breach Existing Dam & Restore Site • Cut Down East Abutment for Access • Remove West Abutment and Spillway • Step Back Remaining East Abutment and Plug Canal Gate • Use Fill to Reshape Slopes Around Dam • Conserve Historic Elements of Dam
Permitting/Approval Process • State/Federal: NRPA, Wetlands Alteration, SHPO, Incidental Taking Permit, • Town: Shoreland, Site Development, Demolition • Pre-application discussions with regulators • Stakeholder review/comments on drafts • Public outreach
Construction • Competitively Bid • H. E. Sargent, Inc. Stillwater, Maine • Early fall - low water conditions • Full time on-site oversight by TU volunteer PE • ME DMR represented fishery agencies • Completed on budget and ahead of schedule
Low flow channel pic
