Overcoming Transmission Line
Siting Challenges
Case Study
Middletown-Norwalk Project
NARUC Transmission WorkshopApril 21, 2011
Albert W. Cretella, III
Presentation Overview
Project Description
Need, Route Options, Steps to ID Best Solution
Siting Challenges
Overhead Lines
Underground Lines
Techniques & Technologies Used
Route Variations & Bypasses
Low Magnetic Field Designs
Underground Cable
River & Rail Crossing Methods
Summary & Closing Thoughts
2
Connecticut Energy Situation
Daily total imports are approximately 1,500 MW
Long Island
RIMA
NY
0
Most of the time Connecticut uses more power than it generates.
Most of Connecticut’s imported power moves on a 345-kV system.
SWCT consumes half the state’s electricity.
But the 115-kV system in SWCT limits the movement of power to where it’s needed
►
►►
► 345-kV
115-kVPower Plant
50%
0
3
Determining a Solution
What is the best combination of solution components?
PROPERTY IMPACT
Impact on homes &
property; Visual impact
ENVIRONMENTAL IMPACT
Impact on wildlife, vernal pools,
aquifers
SYSTEM BENEFIT
Operability†,
Reliability†
TECHNICAL FEASIBILITY
Can it be engineered? Can
it be built?
COST to CUSTOMERS
Engineering and
Construction Costs
† Per national and regional reliability standards.
What are the components of the solution?
Overhead Point-to-Point
Options
Underground Point-to-Point
Options
Evaluate each option based on
these criteria
Evaluate each combination based
on these criteria
What needs to be done?*
* Per regional planning led by
ISO-New England.
1.Strengthen power source to a point in Wallingford
2. Connect that source to substations in Milford, Bridgeport, and Norwalk
1
1
2
2
2
4
Middletown
Norwalk
2
2
2S/S
S/S
S/S
1
1
S/S
To meet national and regionalreliability standards…
Step 1: What needs to be done?
5
Step 2: What are the options?
6
I-91, I-95
Wilbur Cross
Amtrak Railroad
Conrail Railroad
East Devon
Scovill Rock
?
Beseck
Transmission ROW
Secondary Roads
7
What is the best combination of solution
components?
What are the components of the
solution?
Overhead Point-to-Point
Options
Underground Point-to-Point
Options
1
Step 3: What are the best options?
PROPERTY IMPACT
Impact on homes & property; Visual impact
ENVIRONMENTAL IMPACT
Impact on wildlife, vernal pools, aquifers
SYSTEM BENEFIT
Operability†,
Reliability†
TECHNICAL FEASIBILITY
Can it be engineered? Can it be built?
COST to CUSTOMERS
Engineering and construction costs
† Per national and regional reliability standards.
Evaluate each option based on
these criteria
Evaluate each combination based
on these criteria
8
Choosing a Route / Design was an Iterative Process
m nDecision
Circle
Environmental Review
Phenix Environmental, Inc.
Historical
Raber Associates
EnvironmentalTopology
Water ResourcesCoastal Area
CulturalSSES
Marine Options
ESS
EMF/ Best Practice
Exponent
CB Ellis
Property Impact
Underground Technology
Underground Construction
PDC
JD Hair
Transmission &
Substation Design
Burns & McDonnell
Routing & Criteria
Burns & McDonnell
HVDC
Black & Veatch
Singer Substation Site
Black & Veatch
Noise
Cavanough & Tocci
General Electric
ISO-NE
NU
System Studies
9
OH 345-kV (circuit miles)
OH 115-kV (circuit miles)
UG 345-kV XLPE
(circuit miles)
UG 115-kV XLPE
(circuit miles)
Greenfield S/S Sites
Upgrade S/S Sites
Acquisition Acres Land / # Homes
M-N Project (Budget
$1.400 B)
52 63 48 5 3 2 28.6
0
Alternative A (Budget
$1.350 B) 67 73 26 5 4 2
81.6 2
Alternative B (Budget
$1.272 B) 78 86 4 5 4 2
142.3 31
M-N Project and Alternatives
10
Middletown-Norwalk Summary
69 miles of 345-kV line
57 miles of 115-kV line
3 new substations
2 existing substation upgrades
Construction in 18 towns
In-Service Date: December 2008
Middletown
Haddam
Durham
Middlefield
Wallingford
Meriden
Cheshire
Hamden
Bethany
Woodbridge
Orange
West Haven
Milford
Stratford
Bridgeport
Fairfield
Westport
Norwalk
24 miles of XLPE underground
45 miles of overhead
1 mile of XLPE underground
56 miles of overhead
Page 11
Why This Solution…
Going underground is 50% shorter
The underground option avoids the environmental and social impacts of having to acquire over 100 acres and up to 29 homes
The reduced length, avoided real estate costs, and construction difficulty make going underground virtually cost-neutral to going overhead
Why underground from Milford to Norwalk?
No ROW expansion is needed except for 2.5 miles in an unpopulated area of Haddam/Middletown
Nine of the 13 towns would see a net reduction in the number of poles in the ROW
Most towns would experience no discernible increase in pole heights from what exists today
Why overhead from Middletown to Milford?
12
EMF
ROW acquisition (condemnation of residential homes)
Viewscape
Permitting (wetland)
Existing ROW rights
Constructability
Overhead
Design & Construction Challenges
13
Magnetic Field Mitigation
New Applicant Requirements:
• Mapping requirement to identify “Statutory Facilities” (i.e., residential areas, private or public schools, licensed child day care facilities, licensed youth camps and public playgrounds) in the vicinity of the proposed OH route.
• Assessment of the impact of electromagnetic fields.
Connecticut Public Act No. 04-246
14
Protection from Magnetic Fields
• Electric fields are a function of
voltage – higher voltage causes
higher electric fields
• Magnetic fields are a function of
current (Amps) – higher current
causes higher magnetic fields
• Power is a function of Volts
times Amps
• For the same amount of power,
higher voltage means less
current therefore lower magnetic
fields
• There is no practical way to
shield magnetic fields, but there
are ways to reduce them
15
Strategies to Reduce Magnetic Fields
1. Add Distance
Widen the ROW
Increase Pole Height
Relocate the Line
2. Optimize phasing to maximize field cancellation
A
B
C
C
B
A
3. Optimize combination of
the structures
16
Split Phase Construction
Structure Type B – 345 kV
Split Phase
Structure Type C – Combination
345/115kV Split Phase
Structure Type E – Horizontal Split
Phase
17
Cross Section 1Scovill Rock S/S to Chestnut Junction (2.6 miles; 335’ ROW)
Middletown
Existing Proposed Option 1 Option 3
80’ 80’ 85’ 80’ 80’ 105’
($2.1M/mile) ($2.1M/mile) ($3.1M/mile)
mG on South/East Edge of ROW
Option 3Option 1ProposedExisting
32.6
18.6
6.2 7.5
mG on North/West Edge of ROW
Option 3Option 1ProposedExisting
33.830.1 28.8 29.6
80’ 80’ 80’
(15 GW Case) (15 GW Case)
18
Cross Section 2Oxbow Junction to Beseck S/S (7.0 miles; 125’ ROW)
Haddam, Durham, Middletown, Middlefield, Wallingford
Existing Proposed Option 2 Option 3
105’
($2.8M/mile) ($6.7M/mile) ($7.5M/mile)
mG on South/East Edge of ROWmG on North/West Edge of ROW
57’ 105’
Option 6 ($TBD M/mile)
135’
Bypass Royal Oak by placing 345-kV
on new ROW.
Existing 115-kV remains.
115-kV 115-kV
62ProposedExisting
13.917.1
12.4 12.4*
6.2
3 62ProposedExisting
8.3*
30.4
12.49.2
6.2
3
* EMF value for 115-kV only
(15 GW Case) (15 GW Case)
19
Royal Oak Neighborhood Bypass
Significant
Wetland
Impacts
Significant
Tree Clearing
Property Condemnation
Bypasses may not be Least Environmentally Damaging Practical Alternative20
Cross Section 7BCheshire Town Line to Cook Hill Junction (0.4 miles; 200’ ROW)
Cheshire
Existing Proposed Option 1 Option 2 ($8.4M/mile) ($9.0M/mile) ($12.5M/mile)
mG on South/East Edge of ROW
Option 2Option 1ProposedExisting
0.4
6.2 5.5
1.1
mG on North/West Edge of ROW
Option 2Option 1ProposedExisting
4.4
17.9
13.4
5.8
90’130’90’
130’
115-kV 115-kV
150’
115-kV
2
(15 GW Case) (15 GW Case)
21
Cross Section 8-SouthPease Road Junction to East Devon S/S (12.0 miles; 165’ ROW)
Woodbridge, Orange, Milford
85’80’
Existing Proposed Option 4 Option 5 ($3.8M/mile) ($5.0M/mile) ($5.5M/mile)
mG on South/East Edge of ROW
Option 5Option 4ProposedExisting
3.9
11.2
1.7 0.6
mG on North/West Edge of ROW
Option 5Option 4ProposedExisting
1.6
16.0
5.92.9
80’80’57’57’
105’
(15 GW Case) (15 GW Case)
110’ 135’
22
Jewish Community Center Bypass
23
Underground
System Limitations Operation &
Maintenance Concerns Traffic/Public & Worker
Safety DOT/Local Constraints Cost Railroad/Bridge/ River
Crossing Methods Soil/Water Handling Conflicts w/other
Utilities Residential & Business
Disruption
Design & Construction Considerations
24
• How much underground cable can system handle
– What are O&M implications of UG lines
• Shortest route is always better – can it be built?
• CT Siting Council approved route along 14 miles of State roadways (shortest and straightest route)
• DOT resisted use of State roadways due to potential traffic impacts and safety concerns
• DOT originally wanted the duct bank 8 feet deep which would be too deep for the heat to dissipate and would reduce the capacity of the line
• DOT wanted all vaults to be located outside of the travel roadway – needed to find off street locations
• How to cross rivers and railroads
Underground Challenges
25
Cable Types
Cable Type
Maximum
Voltage
Electrical
Advantages
Electrical
Disadvantages
High-pressure Fluid-filled
(HPFF) 345kV +
Most Common at
>230kV
Higher VAR
Consumption,
Leaking oil
High-pressure Gas-filled
(HPGF) 138kV Lower Capacitance
Higher VAR
Consumption,
Uncommon
Extruded-dielectric
(XLPE) 345kV +
Higher Rating than
HPFF, Lower VAR
Consumption, Low
Maintenance
New to the United
States at 345kV+
Extruded-dielectric (EPR) 138kV
More Flexible than
XLPE
Higher Electrical
Losses than XLPE
Self-contained Fluid-filled
(SCFF) 345kV + High Voltages
Dielectric Fluid,
Higher VAR
Consumption than
XLPE, Uncommon 26
• Maximizing system reliability – minimize splices
• Cable length that can be loaded on reels – maximum 1800 feet
• Electrical requirement to space each set of 4 vaults about equally
• Maximum cable pulling tensions
• Location of water and railroad crossings - fixed or “hard coded” vault
locations due to river crossings
• Maximizing the number of off-street vault locations
• Minimizing impacts to existing businesses (condemnation and
business disruption claims)
• Location of off road wetlands
• Avoidance of existing utilities
• Avoidance of intersections
Factors Impacting Vault Locations
27
Water / Rail Crossing Methods
• Horizontal Directional Drill (HDD)
• Horizontal Auger (Jack and Bore)
• Self-Supporting Utility Bridge
• Open Cut (Trenching with Cofferdams)
• In-Street Trenching
• Attachment to DOT Bridges
Evaluation Criteria
• Conformance with Siting Council Decision and Order
• Minimize Impact to the Environment
• Minimize Social Impact
• Minimize Construction Risk
• Minimize Construction Schedule
28
UG Route Change
No feasible
crossing
method
Very busy
commercial
area
29
Options to Cross Ash Creek
ConnDOT Bridge Attachment
• Structurally Infeasible
HDD – Unacceptable Risks
Unfavorable Subsurface Conditions
• Mixed Face Soil Conditions /
Shallow Drill Path - Risk of
Construction Failure – Release
of drilling mud (Frac-Out)
Staging Area - Unsatisfactory
• Demolition of business at 58 Post Road in Fairfield
• Eliminates Entire business parking Lot in Bridgeport for 2 - 3 months
Jack & Bore – Not Constructible
Open Cut – Environmentally Devastating
30
Ash Creek Crossing
Original Proposal
• Self-Supporting Utility Bridge
• 160 Foot Clear Span
• 4 - 5 Month Construction Duration
• Bridge Located Outside of Town Public Access Easement
• Design Provides Shoreline Access Around Bridge Abutments and Under Bridge
• Minor Impacts to Intertidal Area
31
Proposed Utility Bridge at Ash Creek
Building Demolition Elimination of Parking for 2-3 months32
Mock-up of Utility Bridge at Ash Creek
This attempt to provide residents a “visual representation” did not go
well and resulted in a petition to DEP due to proposed crossing method
33
Ash Creek Permitting Background
• Extensive feasibility / design completed to determine the
least environmentally damaging practical alternative
• DEP hearings conducted due to petition associated with
the construction method
• After DEP hearings and extensive discussion the Town
of Fairfield, City of Bridgeport, ConnDOT and DEP
eventually agreed to permit an HDD within the State
roadway under the existing bridge
• Town of Fairfield, City of Bridgeport and ConnDOT
signed Memorandum of Understanding to ensure that all
understood the impacts of an HDD within the roadway
34
Ash Creek Horizontal Directional Drill
• One circuit on each side of road
• Each circuit bundle of 5 conduits
• Drill path was “steep and deep” to get
under bridge abutments
• Circuits separated and spaced far
apart to address cable overheating
concerns
• Construction mostly night work in 12-
hour shifts 6 days per week35
Ash Creek-Northwest Corner
36
Ash Creek-Northeast Corner
37
Construction Duration for Each HDD
• 30 days to install traffic
control and Mobilize HDD
equipment
• 8 days to drill pilot hole
• 30 days to ream pilot hole to
proper diameter
• 45 days to fuse conduits for
pull back
• 2 days conduit pull back
• 12 days to clean/test conduits
• 30 days to remove traffic
control, restore road and
demobilize
NOTE: Blue items occur in
expanded work zone.
Each HDD took over 5 months to complete
Typical Horizontal Directional Drill Setup38
Saugatuck River Crossing
39
Saugatuck River Crossing
• Horizontal Directional Drill
• 1563 feet in length – Max
40’ deep
• 2 – 3 month construction
duration
• Subsurface conditions –
Marginal
• Drill side staging area –
Adequate
• Conduit side staging area
– somewhat constrained
residential street
Result
• Hit target exit point
• Frac-outs cleaned up with
no impacts to coastal /
environmental resources40
Managing Stakeholder Conflicting Priorities
• State Siting Authority
• Federal Agencies - ACOE, NPS, USF&W, OLISP
(Office of Long Island Sound), etc.
• Municipal Leaders
• State Dept. of Transportation
• State Dept. of Environmental Protection
• State Dept. of Health
• Residents
• Businesses
• Other Utilities
Communication, engagement and compromise for
the greater good are essential
41
ConfigurationCircuit Miles
$ M/Circuit Mile
Range / AveInfluencing Factors
345-kV OH 52 $2.3 – 4.0 / $3.4Single / Double Circuit
Low EMF Designs
345-kV UG 46 $12.8 - 13.9 / $13.2Double Circuit Duct Bank
River / RR Crossings
115-kV OH 63 $1.5 – 3.0 / $2.1 Single / Double Circuit
115-kV UG 1 $7.5 / $7.5 Single Circuit Duct Bank
M-N Project Cost Summary
Underground transmission lines can cost 4 to 6 times more than
overhead transmission lines on an adequately sized existing ROW
42
Closing Thoughts
• Every projects’ use of various technologies must be evaluated on its own merits
• Cost/mile comparisons of OH and UG can be deceiving
• State Siting Regulators should strive to streamline / shorten the siting approval process – 2 plus years is too long
• State Siting Regulators should be cautious about delegating decisions to municipalities
• Legislators can provide
leadership roles in
coordinating stakeholders –
State and Federal agencies,
municipal leaders,
businesses and residents 43
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