CITY OF NORTHAMPTON
DEPARTMENT OF
PUBLIC WORKS
Edward S. Huntley, P.E.
Director
James R. Laurila, P.E.
City Engineer
125 L...
Page 2
Presenters
GZA GeoEnvironmental, Inc.
Ander B. Bjarngard, P.E. – Principal-In-Charge
Chad W. Cox, P.E. – Associate ...
Page 3
Presentation Highlights
1. Hazard Classification
2. Dredging
3. Hydropower
Considerations
4. Cost Comparisons
Page 4
Hazard Reclassification
• High Hazard: defined in the Dam Safety
Regulation 302 CMR 10:06(3) as “Dam located
where ...
Page 5
Hazard Classification
• Dam
Page 6
Dam Safety History
• Inspections since 1960’s rate dam as
“Poor/Unsafe”
• Dam removal briefly considered in
1976, b...
Page 7
Hazard Classification
Page 8
Scope of Work for
Hazard Reclassification
1. Evaluate existing data
2. Perform detailed H&H analyses for Middle
Rob...
Page 9
Hazard Classification vs. Level of Repair
• If Hazard Reclassification is pursued, it would
be to lower from “High”...
Page 10
Hazard Classification vs. Level of Repair
• Significant Hazard does lower the Design
Storm from the 500-yr to the ...
Page 11
Stability and Historic Performance
• 302CMR10.14(9)(k) allows historic
performance to be considered in stability
e...
Page 12
Stability and Historic Performance
Page 13
Bathymetric Survey
Existing Bottom
Page 14
Bathymetric Survey
Profile
Total Volume of
Sediment ~ 27,000 CY
Up to 13± feet thick
East End of Alluvial Island
C...
Page 15
Dredging of
Upper Roberts Meadow Reservoir
• Approximately 47% of the
reservoir is silted-in.
• Avg. reservoir dep...
Page 16
Hydropower Considerations
• In Sept 2009, GZA performed a preliminary hydropower
assessment and confirmed that hyd...
Page 17
Hydropower Considerations
Page 18
Hydropower Considerations
Page 19
Hydropower Considerations
• GZA:
– “Based on this preliminary analysis, the
assumed current energy values, and GZA...
Page 20
Hydropower Considerations
• Essex:
– “For hydropower to be economically feasible at
the Upper Dam, the owner/devel...
Page 21
Hydropower Considerations
• Neighborhood Net Metering:
– “Neighborhood Net Metering” is applicable for facilities
...
Page 22
Hydropower Considerations
• Tighe & Bond (Peer Review):
– “Tighe & Bond’s estimate of cost and revenue
from this p...
Page 23
Cost Comparison
Page 24
Conclusions
1. Changing the hazard class for the dam is not
likely. If it is pursued, it will be costly and time
c...
Page 25
Questions?
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GZA Upper Roberts Meadow Dam Public Forum Presentation 10-27-10

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GZA Upper Roberts Meadow Dam Public Forum Presentation 10-27-10

  1. 1. CITY OF NORTHAMPTON DEPARTMENT OF PUBLIC WORKS Edward S. Huntley, P.E. Director James R. Laurila, P.E. City Engineer 125 Locust Street Northampton, MA 01060 Tell 413-587-1570 Fax 413-587-1576 1 Public Forum Upper Roberts Meadow Reservoir Dam October 27, 2010 Northampton DPW GZA GeoEnvironmental, Inc.
  2. 2. Page 2 Presenters GZA GeoEnvironmental, Inc. Ander B. Bjarngard, P.E. – Principal-In-Charge Chad W. Cox, P.E. – Associate Principal Matthew A. Taylor, P.E. – Sr. Project Manager
  3. 3. Page 3 Presentation Highlights 1. Hazard Classification 2. Dredging 3. Hydropower Considerations 4. Cost Comparisons
  4. 4. Page 4 Hazard Reclassification • High Hazard: defined in the Dam Safety Regulation 302 CMR 10:06(3) as “Dam located where failure will likely cause loss of life and serious damage to home(s), industrial or commercial facilities, important public utilities, main highway(s), or railroad(s). • Dam in Series: defined in the Dam Safety Regulation 302 CMR 10.06(4):“If an upstream dam has the capability to create failure in a downstream dam because of its failure flood wave, it shall have the same or higher hazard classification as the downstream dam.”
  5. 5. Page 5 Hazard Classification • Dam
  6. 6. Page 6 Dam Safety History • Inspections since 1960’s rate dam as “Poor/Unsafe” • Dam removal briefly considered in 1976, but design & permitting ceased pending more detailed evaluation • Change in Dam Safety Regulation in 2005 transferred dam safety inspection responsibility from Commonwealth to dam owners (i.e., the City)
  7. 7. Page 7 Hazard Classification
  8. 8. Page 8 Scope of Work for Hazard Reclassification 1. Evaluate existing data 2. Perform detailed H&H analyses for Middle Roberts Meadow Reservoir Dam 3. Perform a probabilistic engineering analyses 4. Total Cost Estimate = $130k to $140k a. There is no guarantee that the results will support lowering the hazard classification of Upper Roberts Meadow Reservoir Dam!
  9. 9. Page 9 Hazard Classification vs. Level of Repair • If Hazard Reclassification is pursued, it would be to lower from “High” to “Significant”. – Changing to “Low” hazard is not likely given Kennedy Road is downstream of the dam. • Changing the hazard class does not lower the required minimum factors of safety (302CMR10.14(9)(k)). • The required level of repair for the Upper Roberts Dam is the same for either a “High” or “Significant” hazard classification.
  10. 10. Page 10 Hazard Classification vs. Level of Repair • Significant Hazard does lower the Design Storm from the 500-yr to the 100-yr. • However, even the normal pool condition (“Usual”) requires improvements to meet the required factors-of-safety per 302CMR10.14(9)(k).
  11. 11. Page 11 Stability and Historic Performance • 302CMR10.14(9)(k) allows historic performance to be considered in stability evaluations to establish design parameters. It does not allow a dam to be considered “adequate” based on past performance. • And, the condition of the dam has deteriorated such that past performance is not representative of future performance. • Significant repairs are needed to meet regulatory requirements and to preserve its historic stability.
  12. 12. Page 12 Stability and Historic Performance
  13. 13. Page 13 Bathymetric Survey Existing Bottom
  14. 14. Page 14 Bathymetric Survey Profile Total Volume of Sediment ~ 27,000 CY Up to 13± feet thick East End of Alluvial Island Cross-Section
  15. 15. Page 15 Dredging of Upper Roberts Meadow Reservoir • Approximately 47% of the reservoir is silted-in. • Avg. reservoir depth = 2.9 ft. • Emergent wetland plants can grow in water up to 3 ft deep. • Based on 27,000 CY of sediment and the last dredging in 1970+/-, the annual bed load is estimated to be about 675 CY. • The reservoir is transitioning to an emergent wetland in about 15 to 25 years if not dredged. • So, saving the dam, without dredging, will not save the pond!
  16. 16. Page 16 Hydropower Considerations • In Sept 2009, GZA performed a preliminary hydropower assessment and confirmed that hydropower is not economically feasible at the Upper Roberts Reservoir. – Max Power 30 kW w/ annual energy of 130 MWh – No direct end user at the dam so the power will be sold to the grid at 1/3 of its retail value (wholesale rates). – Average value of generated energy = $13,000/year – FERC licensing will take 5 yrs and cost at least $100,000 – Estimated total project cost = $750,000 to $1,000,000 (Updated Cost Estimate $885k per GZA, June 2010) – Payback Period = 58-77 years (excluding cost of new transmission lines) – The project is not currently eligible for funding under the previously available MTC grant program.
  17. 17. Page 17 Hydropower Considerations
  18. 18. Page 18 Hydropower Considerations
  19. 19. Page 19 Hydropower Considerations • GZA: – “Based on this preliminary analysis, the assumed current energy values, and GZA’s understanding of the goals of the City in developing alternative energy projects, we do not believe that the Upper Roberts Reservoir Dam is a viable hydroelectric project site.” (GZA, Sept 2009).
  20. 20. Page 20 Hydropower Considerations • Essex: – “For hydropower to be economically feasible at the Upper Dam, the owner/developer will have to secure rates that are substantially higher than the wholesale market for the energy produced….Threshold costs for licensing, environmental studies, engineering and design make the development of micro-hydro difficult. One way to help overcome these costs would be to develop multiple projects on a river system….it would be difficult to develop a single micro-hydro project such as the Upper Dam.” (Essex, Aug 2010)
  21. 21. Page 21 Hydropower Considerations • Neighborhood Net Metering: – “Neighborhood Net Metering” is applicable for facilities that serve a group of 10 or more residential customers in a single neighborhood and served by a single utility. – This would likely require a dedicated physical transmission line to one house in the “neighborhood” from the powerhouse at the dam along with utility grade switchgear. – In order for the City to realize the revenue generated by the hydropower project at the dam, the City will need to bill and collect fees at standard commercial rates from the “neighborhood”. – Under the “Neighborhood Net Metering” arrangement, the City will take on the role as a power company!
  22. 22. Page 22 Hydropower Considerations • Tighe & Bond (Peer Review): – “Tighe & Bond’s estimate of cost and revenue from this project is similar to that of GZA, resulting in what we conclude is an unacceptable payback period for the City…the project does not meet its objective and will not effectively aide the City in paying future operation and maintenance costs associated with the Upper Roberts Meadow Reservoir Dam. ” T&B, Sept 2010).
  23. 23. Page 23 Cost Comparison
  24. 24. Page 24 Conclusions 1. Changing the hazard class for the dam is not likely. If it is pursued, it will be costly and time consuming. 2. If even if the hazard class is changed, it does not change the scope of the repair work required. 3. Dredging is needed for both dam rehab and dam removal. The pond is already of turning into a wetland. 4. Hydropower is not economically feasible based on GZA’s and Tighe and Bond’s cost estimates. Even Essex Partnership notes that securing retail rates is required for it to be a viable single project.
  25. 25. Page 25 Questions?

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