12-010.01
Open Loop Heat Pump Wells:
1. Water wells intended only to withdraw
water must comply with 178 NAC 12004, Potable Water Wells.
2. Water wells intended only to inject ground
water must comply with Nebraska Department of Environmental Quality's Title 122
- Rules and Regulations for Underground Injection and Mineral Production
Wells.
12-010.02
Closed Loop Heat Pump Wells: Water wells for closed
loop heat pump systems must be constructed in accordance with the following
standards.
12-010.02A For a closed loop heat
pump system that has 10 or more boreholes, the following information must be
submitted to the Department a minimum of 14 working days prior to initial
construction.
1. Location of
project;
2. Name and address of
licensed water well contractor supervising the installation of the heat pump
system; and
3. A completed copy of
the information referenced in 178 NAC 12-003.12A, showing proposed construction
and installation of the closed loop heat pump system.
12-010.02B
Location:
All water wells constructed for closed loop heat pump systems must be located
in accordance with 178 NAC 12-003.01.
12-010.02B1
Location from a
Public Water System Well
12-010.02B1a The location of closed loop heat
pump wells must comply with 178 NAC 12-003.01C item 1. Be aware that other
state and local statutes and regulations may have more restrictive
requirements. If locations do not comply with more stringent standards of other
applicable state or local regulations, the Department may notify the
appropriate authority, which could require the well to be
decommissioned.
12-010.02B1b Water
wells constructed for a closed loop heat pump system must be located more than
100 feet from a non-community public water system well.
12-010.02B1c A closed loop heat pump system
must be located more than 1,000 feet from a community public water system well.
The Department will consider approval for location of closed
loop heat pump wells at closer proximity than 1,000 feet horizontal separation
distance, when the licensed professional engineer or licensed professional
geologist representing the owner(s) of the closed loop heat pump wells,
demonstrates to the Director or Director's designee that such location will not
constitute a pollution hazard to the safety of the water supply, and that the
owner(s) of the community water system has no objection to the location of the
closed loop heat pump wells.
The engineer or geologist must submit the supporting data as
appropriate to make a case for approval of the proposed location of heat pump
wells to the Department 30 working days prior to the date on which action by
the Director or Director's designee is desired. The contractor must not begin
construction until the Department has approved the location.
12-010.02C
Borehole Diameter: The borehole diameter of a closed
loop heat pump well must be of sufficient size to allow placement of the pipe
and placement of a tremie to emplace the grout. The borehole diameter must be a
minimum of 4 inches larger than the total OD of the loop pipes.
12-010.02D
Pipe:
Pipe material must be composed of polyethylene, grade p34, minimum cell
classifications PE 355434C or PE 345434C, when tested under ASTM Standard 3350,
incorporated herein by reference. (ASTM standards are copyrighted and available
from the American Society for Testing and Materials International, 1916 Race
St., Philadelphia, PA 19103; Phone 215-299-5585, Fax 215-977-9679, 100 Barr
Harbor Drive, P.O. Box C700, West Conshohocken, PA 19428-2959 USA; Phone:
610-832-9500;
http://www.astm.org.
Standards may be viewed during normal business hours at the Nebraska Department
of Health and Human Services, Division of Public Health, 301 Centennial Mall
South, 3rd Floor, Lincoln, NE 68509.)
12-010.02E
Pipe Joining
Method: Heat fusion methods for pipe joining must be the socket or
butt heat fusion technique as referenced in ASTM Standards D3261 or D2683, both
of which are incorporated herein by reference. (ASTM standards are copyrighted
and available from the American Society for Testing and Materials
International, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA
19428-2959 USA; phone: 610-832-9500;
http://www.astm.org; OR standards may be
viewed during normal business hours at the Nebraska Department of Health and
Human Services, Division of Public Health, 301 Centennial Mall South,
3rd floor, Lincoln, NE 68509.)
12-010.02F
Pressure
Testing: The installed system must be pressure tested to a minimum
of 100 pounds per square inch (psi). After 6 hours it is permissible for the
pressure to drop a maximum of 15% of the initial psi due to expansion of the
HDPE piping. A pressure loss greater than 15% in 6 hours is an indication of a
leak in the circulating system. If a pressure loss is detected, the cause must
be properly repaired, the material replaced, or the well must be properly
decommissioned.
12-010.02G
Purging a Loop System: After a loop system is
installed and pressure tested, and prior to introducing additives to the
circulating fluid, the entire loop, header and associated plumbing must be
purged at a minimum rate of 5 feet per second to remove any debris that has
entered the loop during construction.
12-010.02H
Circulating
Fluids: When food grade propylene glycol is added to water for
antifreeze protection, it must be non-toxic in nature when combined with the
circulating fluid additives in a closed loop heat pump system. If needed, the
addition of corrosion inhibitors and biocides may be used in circulating fluid
if such additives are also:
1. Non-toxic;
and
2. Compatible with food grade
propylene glycol; and
3.
Non-hazardous materials upon disposal or a change of circulating
fluid.
12-010.03
Completion of a
Vertical Closed Loop System: Completion of a borehole for a closed
loop heat pump well must be finished within 6 hours from the time the borehole
is drilled. Drilling muds or cuttings cannot be used as completion materials.
The tremie pipe must not be left in the borehole.
12-010.03A Systems that have 10 or more
boreholes must be grouted full-length with high solids bentonite slurry in
accordance with 178 NAC 12-003.06 item 5. (See Figure 11A)
12-010.03B Systems that have fewer than 10
boreholes must be grouted full-length with high solids bentonite slurry in
accordance with 12-003.06 item 5 when they are located less than 1000 feet of a
community public water well (which requires prior written permission from the
community). (See Figure 11B)
12-010.03C Systems that have fewer than 10
boreholes and are located 1000 feet or more from a community public water well
must use one of the following methods to complete construction of the
boreholes: (See Figure 11C)
1. High solids
bentonite slurry that meets the requirements of 178 NAC 12.003.06 item 5 must
be used to grout the full length of the borehole, or
2. Sand or gravel must be placed through the
sodium bentonite fluid with a viscosity that allows the sand to settle through
the fluid from the bottom of the borehole to the static water level by tremie
or free fall method. A 5 foot interval of bentonite chips must be placed at the
static water level, and the remainder of the borehole must be sand/gravel
packed through the fluid to within 30 feet of the surface minus excavation for
the header piping. The remaining annular space must be filled with non-slurry
bentonite chips.
12-010.04
Horizontal Closed Loop
System
12-010.04A A horizontal
closed loop heat pump system that is constructed by trenching or digging is
exempt from the grouting requirements of closed loop systems provided that no
part of the horizontal loop is constructed at or below the ground water
level.
12-010.04B A horizontal
closed loop heat pump system constructed by boring or drilling must be grouted
with high solids bentonite slurry grout that meets the requirements of NAC
12-003.06 item 5.
12-010.04C All
other construction standards for closed loop heat pump wells in 178 NAC 12-010
apply.