Or. Admin. R. 690-230-0085 - Pump Testing of Low-Temperature Geothermal Injection Wells With an Anticipated Injection Rate Exceeding 15,000 Gallons Per Day
(1) Low-temperature
geothermal injection wells (other than flowing artesian wells) with an
anticipated injection rate of greater than 15,000 gallons per day, shall be
pump tested for a period for at least four hours. The pump test shall occur
after the owner's pump test plan is approved by the Director , and prior to
injecting into the well. The results of this test do not need to appear on the
water well report. This test shall be in addition to the minimum one-hour test
requirement under OAR
690-210-0370.
Requirements for conducting the minimum four-hour pump test as discussed in
this section (this type of test) are as follows:
(a) Prior to testing, the well shall be idle
for a period of at least four hours;
(b) The static water level in the well shall
be measured at least three time, no less than twenty minutes apart, during the
hour prior to pumping the well;
(c)
The water shall be pumped into or from the well at a measured and steady rate.
The rate shall approximate the maximum anticipated injection rate;
(d) The pump discharge shall be controlled as
much as possible to maintain a constant rate during the test. The discharge
rate shall be as close as reasonably possible to the anticipated injection rate
during normal use of the well. Discharge rate shall be recorded at the
beginning of the test and once every hour thereafter;
(e) Water levels in the well shall be
physically measured by a standard and acceptable method. Visual estimation of
water level is not acceptable. Acceptable methods include:
(A) An electric water level measuring
tape;
(B) An air line dedicated to
the well;
(C) An acoustic
sounder;
(D) An electronic pressure
transducer; or
(E) Other water
level measuring methods approved in advance by the Director .
(f) The water level measurements
shall occur at least at the minimum frequency outlined below: Time period --
Water level measurement schedule:
(i) First 10
minutes -- No more than 2 minutes apart;
(ii) 10 to 30 minutes -- No more than 5
minutes apart;
(iii) 30 to 100
minutes -- No more than 15 minutes apart;
(iv) 100 to 240 minutes -- No more than 30
minutes apart.
(g) After
pumping stops, water level measurements shall be collected for a time equal to
that of the pumping period, or until the well reaches 90 percent recovery from
the maximum drawdown, whichever occurs first. Recovery water level measurements
shall be collected on the same time schedule as described in subsection (1)(f)
of this rule;
(h) The pump
discharge shall be physically measured by a standard and acceptable method.
Visual estimation of flow rate is not acceptable. Acceptable methods include:
(A) A properly installed flow meter, designed
for geothermal use, which is functional and calibrated within reasonable limits
for the type of meter;
(B) A
properly installed weir or flume;
(C) A properly installed and calibrated
orifice plate and manometer;
(D)
Known volume/time calculations (including calibrated bucket and stopwatch up to
60 gallons per minute);
(E)
Properly installed and used ultrasonic flow measuring devices; or
(F) Other discharge methods approved in
advance by the Director .
(2) The owner may consult with the Department
before selecting representative nearby wells for monitoring during the pump
test. If monitoring wells are selected in absence of specific instructions from
the Department , the measurement of water levels in each well shall adhere to
the schedule established in subsection (1)(f) of this rule.
(3) The Director may require the owner of the
well to have a pump test performed that is more detailed than the test
requirements described in sections (1) and (2) of this rule. This more detailed
test could include, but is not limited to, increased frequency of water level
measurements, increased test duration and increased monitoring of observation
wells. Such modifications will be required when possible impacts resulting from
the proposed injection include, but are not limited to, thermal or hydrologic
interference with existing water rights, water quality degradation or physical
or mechanical failure of the well structure.
(4) For flowing artesian wells, pump test
specifications shall be prescribed by the Department on a case-by-case
basis.
Notes
Stat. Auth.: ORS 537
Stats. Implemented: ORS 537
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