WEE WAH LAKE DAM AND POND No. 3 DAM REHABILITATION PROJECT Village of Tuxedo Park Meeting: March 15, 2017 1. So the task at hand was to understand…how to improve stability of a dam 2. Recognize the “previous modes”... post-tensioned anchors through the dam 3. Expand on them and take a more inclusive approach which was to consider passive rock mass reinforcement.

Critical Dam Safety Criteria Wee Wah Lake Dam Is Spillway Capacity sufficient to pass SDF (50% of PMF) Stability of the concrete gravity and earthen embankment Can outlet works effectively drawdown the pool level in event of dam emergency

Wee Wah Lake Dam Left Abutment Stilling Basin Wee Wah Road (Crest of Dam) Earthen Embankment Auxiliary Spillway 1. So the task at hand was to understand…how to improve stability of a dam 2. Recognize the “previous modes”... post-tensioned anchors through the dam 3. Expand on them and take a more inclusive approach which was to consider passive rock mass reinforcement. Wee Wah Lake Service Spillway Stop Log Gate Right Abutment

Contract Drawings & Permitted Improvements Clear Brush and Large Trees and Flatten D/S Slope, Provide Drainage and Monitoring

Contract Drawings & Permitted Improvements Construct Low Level Outlet w/in Service Spillway

Contract Drawings & Permitted Improvements

Service Spillway Service Spillway & LLO Service Spillway (Crest El 496.9’) Service Spillway Weir Currently at El. 492.5’, New El. 492’ 1. So the task at hand was to understand…how to improve stability of a dam 2. Recognize the “previous modes”... post-tensioned anchors through the dam 3. Expand on them and take a more inclusive approach which was to consider passive rock mass reinforcement. Service Spillway Service Spillway & LLO

Contract Drawings & Permitted Improvements Repair and Improve Stability of Auxiliary Spillway, Mitigate Seepage Discharge through Floor of Spillway Structure

Auxiliary Spillway (Left Side) Auxiliary Spillway Weir El. 493.0’ currently, new crest to El. 492.5’ Auxiliary Spillway Training Wall 1. So the task at hand was to understand…how to improve stability of a dam 2. Recognize the “previous modes”... post-tensioned anchors through the dam 3. Expand on them and take a more inclusive approach which was to consider passive rock mass reinforcement. Auxiliary Spillway (Left Side)

Auxiliary Spillway (Left Side) Auxiliary Spillway Weir El. 493.0’ Auxiliary Spillway Training Wall Leakage Through Auxiliary Spillway 1. So the task at hand was to understand…how to improve stability of a dam 2. Recognize the “previous modes”... post-tensioned anchors through the dam 3. Expand on them and take a more inclusive approach which was to consider passive rock mass reinforcement. Auxiliary Spillway (Left Side)

Auxiliary Spillway (Lower Floor) Seepage Discharge through Auxiliary Floor Reinforced Concrete Slabs over Pore water Relief Wells Auxiliary Spillway Stone/Masonry Floor 1. So the task at hand was to understand…how to improve stability of a dam 2. Recognize the “previous modes”... post-tensioned anchors through the dam 3. Expand on them and take a more inclusive approach which was to consider passive rock mass reinforcement. Auxiliary Spillway (Lower Floor)

Contract Drawings & Permitted Improvements

Contract Drawings & Permitted Improvements Construct Parapet Wall along Crest of Dam

Parapet Wall Parapet Wall Along Right Side of Road Wall Alignment 1. So the task at hand was to understand…how to improve stability of a dam 2. Recognize the “previous modes”... post-tensioned anchors through the dam 3. Expand on them and take a more inclusive approach which was to consider passive rock mass reinforcement. Left Abutment Parapet Wall

Contract Drawings & Permitted Improvements Wee Wah Road (Dam Crest) at approx. El. 498 Parapet Wall

Pond No. 3 Dam Left Abutment Earthen Embankment Discharge Channel to Wee Wah Lake (Crest of Dam) 1. So the task at hand was to understand…how to improve stability of a dam 2. Recognize the “previous modes”... post-tensioned anchors through the dam 3. Expand on them and take a more inclusive approach which was to consider passive rock mass reinforcement. Low Level Outlet Channel Beneath Splash Pad Third Pond Primary Spillway Right Abutment

Critical Dam Safety Criteria Pond No. 3 Dam Is Spillway Capacity sufficient to pass SDF (the 100-yr Storm) Structural Stability of the stone masonry and earthen embankment segments of the dam. Can outlet works effectively drawdown the pool level in event of dam emergency

Contract Drawings & Permitted Improvements Intake Discharge Flow Priming and Control Vault LLO Siphon System

Contract Drawings & Permitted Improvements Flow Priming and Control Vault Intake Discharge LLO Siphon System

Contract Drawings & Permitted Improvements Sound Mortar Repointing Stone Masonry Open Masonry Joints

Questions?