Pierre River Mine Project

WATER AENV SIRS 15 – 43
Reference
Section 12.1
model, steady-state calibration) and Figure 23 (Pierre River Mine local model,
steady-state calibration).
The maximum and minimum residual values represent a small portion (less than
5%) of all calibration data and, therefore, should not be solely relied upon for an
evaluation of the appropriateness of model calibration. Reilly and Harbaugh
(2004) indicate that an evaluation of the appropriateness of the model in
representing the problem objectives is more important than the values measuring
the goodness of fit. Figure 21 of EIA, Volume 4B, Appendix 4-1 indicates that
there was a good fit between measured and simulated head declines at various
distances from the depressurization centres (pumping wells). This observation,
combined with reasonable quantitative measures of model error, shows that,
based on the available data, the model provides an accurate representation of the
groundwater system under consideration, as shown in Figure 6.3-53 for the basal
aquifer and in Figure 6.3-62 for the surficial deposits (EIA, Volume 4A).
Reilly, T.E. and A.W. Harbaugh. 2004. Guidelines for Evaluating Ground-Water
Flow Models. U.S. Geological Survey Scientific Investigations Report
2004-5038.
Request 18b Provide statistical analysis of residuals in the wells in close proximity to the
abovementioned areas and discuss the validity of residuals in those areas.
Response 18b The data available for calibration in the area of the Pierre River Mine included 18
static groundwater levels in surficial aquifers, one static groundwater level in the
McMurray Formation oil sands, and 16 static groundwater levels in the basal
aquifer. Individual residual values for wells in the area of the Pierre River Mine
were presented in EIA, Volume 4B, Appendix 4-1, Table 2 for the regional
steady-state model and in Table 10 for the Pierre River Mine local steady-state
model.
For the residual values shown in Table 10, the range is between -8.02 m and
+10.77 m; the residual mean is 1.04 m; the median is 1.28 m; and the standard
deviation is 4.55 m (see Figure 23 of EIA, Volume 4B, Appendix 4-1, page 97).
The 5, 20, 40, 60, 80 and 95 percentiles are approximately -7.1, -2.9, -1.3, 1.9,
4.8 and 8.8 m, respectively. Further statistical analysis on a subset of the data
shown in Table 10 would not be statistically meaningful because of the small size
of the subsets.
Request 18c The mass balance information provided in Response 279b suggests that the
major component of the inflow to the system in the regional model is from
recharge boundary and major outflow from the system is from drain boundaries.
Provide comments related to input parameters used in the inflow and outflow
boundaries in the model when answering questions d to f below.
April 2010 Shell Canada Limited 12-11
CR029