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GZA Upper Roberts Meadow Dam Public Forum Presentation 10-27-10
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. 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
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.”
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)
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. 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. 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. 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.
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. 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.
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. 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. 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. 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).
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.
