40
assessing radionuclide leaching behavior, a follow-up geochemical testing program is being
designed to ascertain the long-term potential for radionuclide mobility (apart from the necessary
ARD testing) in waste rock and pit wall effluent.
The primary objective of the radionuclide leaching program is to evaluate if the radioactive
constituents present in the source rock will be mobilized under the range of environmental
conditions expected to exist at the Waste Rock Facility and Mineable Pit. To achieve this
objective, a modified short-term leach test (the synthetic precipitation leaching procedure or
SPLP) will be used to evaluate the effects of prolonged contact time (24 to 48 hours) of waste
rock material in contact with weakly acidic water (representing dilute meteoric water). The
resulting leachate will be analyzed for a complete analytical suite, including radionuclides. The
standard SPLP test will be modified to (a) consider a range of pH and alkalinity values, (b)
assess a more concentrated water to rock ratio (well below the standard 20:1 ratio), and (c)
attempt to constrain solubility and/or sorption controls on radionuclide mobility for each rock
type by repeating the test for each waste rock sample multiple times. If the radionuclides appear
to be mobile under the conditions assessed in the modified SPLP tests, additional saturated
continuous-flow column experiments will be conducted to determine the long-term release rates
and concentrations of the radionuclides. Column experiments will be conducted for whatever
length of time is required for relevant reaction rates to become stable and quantifiable. The
information gained from this testing program will be used to determine potential source terms in
the solid phase, assess the mobility of the radionuclides, and to determine the potential
magnitudes and rates of release of radioactive constituents to the aqueous phase.
Preliminary static testing for Bull Hill Resource Area has been completed. The results indicate
that the waste rock and pit wall demonstrate little potential to generate acid. ABA and NAG test
pH data for four common pit lithologies are summarized as follows (tests performed on all
samples unless otherwise noted):
Overburden (four samples):
o
ANP values range from 2 to 11 TCaCO
3
/kT
o
AGP; calculated from sulfide sulfur - values range from 0.6 to 2.2 TCaCO
3
/kT
o
Neutralization Potential Ratio (NPR; Price 2009) values range from 2.3 to 11.7.
All samples fall into the NPAG (not potentially acid generating) category).
o
Net Neutralization Potential (NNP; White et al., 1998) values range from 1.4 to
10.1 TCaCO
3
/kT. All samples fall into the Uncertain category.
o
Paste pH values range from 6.6 to 9.3
o
NAG pH value equals 7.4 (one sample)
Tonalite Trachyte Porphyry (25 samples):
o
ANP values range from below detection limit (<DL) to 36 TCaCO
3
/kT
o
AGP values range from 0.2 to 4.1 TCaCO
3
/kT
o
NPR values range from 0.1 to 192. One sample falls into the PAG (potentially
acid generating), two are classified as Uncertain, and 22 samples are NPAG.
o
NNP values range from -4.1 to 34.4 TCaCO3/kT. Twenty-one samples are
classified as Uncertain, 4 samples as NPAG.
o
Paste pH values range from 6.6 to 8.3
o
NAG pH values range from 7.2 to 8.4 (10 samples)
