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TRANSCRIPT
Well Field Developer
David Lamothe, P.E.
GZA GeoEnvironmental, Inc
Panel Discussion: Genesis of a Geothermal Project
2
Genesis of a Geothermal Project
Development of the Well Field
EBC Renewable Energy Program
Geothermal Energy Development in New England
April 11, 2012
David Lamothe, P.E., IGSHPA AI
Senior Project Manager
GZA GeoEnvironmental, Inc.
603-232-8716
3
GZA and Geothermal – 3-Phase Approach
Phase I - Feasibility Study
Educate Owners
GZA w/ Energy Modeler, System Designer inputs
Recommend a ground loop type (SCW, CL, ODW)
Test well
Phase II - Design
System Designer w/ GZA input
Phase III - Installation
Driller w/ GZA observation
4
GZA and Geothermal – 3-Phase Approach
Phase I - Feasibility Study
Educate Owners
GZA w/ Energy Modeler, System Designer inputs
Recommend a ground loop type (SCW, CL, ODW)
Test well
Phase II - Design
System Designer w/ GZA input
Phase III - Installation
Driller w/ GZA observation
5
Geothermal Feasibility Study
Physical restrictions – available space for well field
Soil, bedrock, and groundwater conditions
Environmental conditions
Permitting requirements
Client’s risk tolerance – O&M, water quality
Estimated payback (typ. provide cost input to team)
6
Selection of Ground Loop
Physical restrictions – available space for well field
Closed loop closer spacing but more wells typ. required
Soil, bedrock, and groundwater conditions
Depth to rock, water quantity and quality
Environmental conditions
Soil or groundwater contamination in vicinity?
AUR/AUL?
Client’s risk tolerance to O&M, water quality issues
(Risk tolerance is often primary factor in selection)
7
Ground Heat Exchanger (Ground Loop)
• Open systems (direct use of groundwater)
– Open to Diffusion Wells (ODW)
100+ feet spacing
– Standing Column Wells
75 to 100 ft on center
• Closed Loops
– Vertical wells
20 to 25 ft on center
– Horizontal
Also - Pond Loops
8
Permit Considerations
State UIC registration
(Underground Injection Control)
MassDEP, RIDEM, CTDEP/CTDPH/CTDCP
More rigorous permitting for Open Loop vs. Closed Loop in Massachusetts
1 page UIC registration for CL
Open systems – UIC registration, water withdrawal reporting/registration/permitting for > 100,000 gpd (=70 gpm), [determination of non-consumptive use]
9
Permit Considerations (Continued)
Open Loop
Raw Water Quality Testing Required
Selected Organics
Primary inorganics (As, nitrate/nitrite)
Radiological (Gross Alpha/Beta, Radium, Uranium)
Secondary inorganics (Na, Cl, Fe, Mn)
pH
Bacteria (total coliform [fecal and E. coli]) for discharge water
Bleed – should return to same aquifer
If > 5% to different aquifer, requires justification
10
Permit Considerations (Continued)
Closed Loop
Allowed antifreeze
Propylene glycol
Ethanol
R-22/134A/407C allowed refrigerants for DX
Pipe Materials
HDPE
Fiberglass
Copper (DX Only)
Grout - Bentonite slurry/Bentonite and sand (cement allowed for DX)
11
GZA and Geothermal – 3-Phase Approach
Phase I - Feasibility Study
Educate Owners
GZA w/ Energy Modeler, System Designer inputs
Recommend a ground loop type (SCW, CL, ODW)
Test well
Phase II - Design
System Designer w/ GZA input
Phase III - Installation
Driller w/ GZA observation
12
Test Well
• Test well or “first” well of the geothermal
well field for consideration in design of
remaining well field
• Obtain site-specific geologic information
(soil, depth to and type of rock, groundwater
quantity and quality)
• Obtain thermal properties via thermal
conductivity test (CL)
• Pump test and water quality testing (SCW or
ODW)
13
GZA and Geothermal – 3-Phase Approach
Phase I - Feasibility Study
Educate Owners
GZA w/ Energy Modeler, System Designer inputs
Recommend a ground loop type (SCW, CL, ODW)
Test well
Phase II - Design
System Designer w/ GZA input
Phase III - Installation
Driller w/ GZA observation
14
Well Field Construction
• Well depth and construction
• Pressure Testing
– U-bends
– Circuits
– Headers
– Well Field
• Circuit piping Configuration
15
Well Field Construction
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Well Field Construction
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Well Field Construction
• Loop photos Looping and grouting
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Well Field Construction
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Well Field Construction
20
Well Field Construction
Vault construction and manifold
21
Well Field Construction
Main supply and return lines
22
New England Geothermal Prof. Assn.
Mission To educate and advocate for the advancement of
the Geothermal Heat Pump industry in New England to increase energy efficiency and reduce
dependency on fossil fuels
www.negpa.org
• To become part of NEGPA
• Information on NEGPA