Tempe Town Lake        Downstream Dam ReplacementNEW DAM ALTERNATIVES SELECTIONJanuary 5, 2012
Timeline * Alternatives Evaluation – June thru November Project Update with Council – September 22 Phase 1 Validate Con...
Dam Design Criteria 1.   Maintain or Improve Current Level of Flood      Protection 2.   Maintain Full Lake Quickly After ...
Regulatory Conditions       Regulatory Agency                    Concerns                                            Water...
Alternatives Evaluation              About 20 Dam Options              Studied:                 Radial (Tainter) Gates   ...
Three Viable Alternatives   Sumitomo Rubber Dam   Obermeyer Gate   Hydraulic Hinged Crest    Gate
Proposed AlternativeLocations Sumitomo – Replacing bladders, same  location                Pedestrian                    ...
Proposed AlternativeLocations Obermeyer – Adjacent to existing dam                              Pedestrian               ...
Proposed AlternativeLocations Hinged Crest Gate–100ft west of existing  dam                              Pedestrian      ...
Life CycleCosts                                                                                             Total         ...
Dam Recommendation Hydraulically Operated Hinged Crest Gate     Safety & Reliability     Durability     Value (cost co...
Dam Financing          Preliminary Capital Cost Estimates: $36           Million          Includes Design, Materials, Co...
Next Steps                                          Public Meeting, Jan. 11, 5:30                                        ...
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Tempe Town Lake dam replacement technology - short version

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This presentation is a condensed look at the dam technology choices considered for Tempe Town Lake. It is the presentation showing at the Jan. 5 Issue Review Session for the Tempe City Council.

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Tempe Town Lake dam replacement technology - short version

  1. 1. Tempe Town Lake Downstream Dam ReplacementNEW DAM ALTERNATIVES SELECTIONJanuary 5, 2012
  2. 2. Timeline * Alternatives Evaluation – June thru November Project Update with Council – September 22 Phase 1 Validate Concept & Select Dam Technology – November 2011 Phase 2 Design New Dam / Acquire Permits – complete by July 2013 Bid and Procure Construction Contract by October 2013 Start Construction by November 2013 Construction Complete – December 28, 2015
  3. 3. Dam Design Criteria 1. Maintain or Improve Current Level of Flood Protection 2. Maintain Full Lake Quickly After Flood Event 3. Raise, Lower and Operate Reliably at Normal Lake Levels 4. Be Cost Efficient – Capital, Lifespan, O&M 5. Have Parts Easily Available 6. Be Compatible with Pedestrian Bridge, Existing Structures 7. Perform Well in this Climate 8. Meet Regulatory Requirements
  4. 4. Regulatory Conditions Regulatory Agency Concerns Water quality, channel conditions, U. S. Army Corps of Engineers 404 permitting Flood Control District of Maricopa Flood control, levee maintenance County Federal Emergency Management Flood control, levees Agency (FEMA) Arizona Department of Water Dam Safety Resources
  5. 5. Alternatives Evaluation About 20 Dam Options Studied:  Radial (Tainter) Gates  Bascule or Bottom-Hinged Leaf Gates  Inflatable Rubber Dams(water and air- filled)  Ogee Crest Weirs  Labyrinth Weirs  Many Styles of Fuse Plugs  Several Styles of Pneumatically-Operated Hinged Crest Gates (Obermeyer)  Hydraulic Hinged Crest Gates  Dyrhoff Rubber Dams (Sumitomo)  Vertical Lift Gates  Swing Gates  Fusegates (Hydroplus)  Earth Embankment/Fuseplug  Several Styles of Mixed-type Spans  Cable-Operated Hinged Crest Gate
  6. 6. Three Viable Alternatives  Sumitomo Rubber Dam  Obermeyer Gate  Hydraulic Hinged Crest Gate
  7. 7. Proposed AlternativeLocations Sumitomo – Replacing bladders, same location Pedestrian Bridge
  8. 8. Proposed AlternativeLocations Obermeyer – Adjacent to existing dam Pedestrian Bridge
  9. 9. Proposed AlternativeLocations Hinged Crest Gate–100ft west of existing dam Pedestrian Bridge
  10. 10. Life CycleCosts Total Total Project Total 50-Year Construction and Alternatives Construction Life Cycle Costs Life Cycle Cost Cost (Present Value) (Present Value)Sumitomo Rubber Bladders - 10 Yr. Rubber Life $40,900,000 $138,300,000 $179,200,000 (Replace Rubber Bladder every 10 years)Obermeyer Gates - 10 Yr. Rubber Life $32,800,000 $41,600,000 $74,400,000 (Replace Rubber Bladder every 10 years)Hinged Crest Gates $35,400,000 $32,700,000 $68,100,000
  11. 11. Dam Recommendation Hydraulically Operated Hinged Crest Gate  Safety & Reliability  Durability  Value (cost competitive)  Engineering Requirements  Regulatory Requirements
  12. 12. Dam Financing  Preliminary Capital Cost Estimates: $36 Million  Includes Design, Materials, Construction  Does Not Include East Dam or Pump System (New East Dam repl. $8M-$10M)  Finance Options Include:  Use Remaining $3,633,000  Seek Voter Approval for Bond Authorization for Dam Replacement Capital Costs  Sale of City Properties  Lease / Purchase Agreement  Combinations
  13. 13. Next Steps  Public Meeting, Jan. 11, 5:30 p.m. Tempe Center for the Arts  Return to Council Jan. 19  Review Financing Options  Design, Permit, BuildWant more information?Visit www.tempe.gov/lakeClick on Town Lake Dam Replacement in the Blue Box

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