S. S. PAPADOPULOS & ASSOCIATES, INC. ENVIRONMENTAL …

S. S. PAPADOPULOS & ASSOCIATES, INC.

ENVIRONMENTAL & WATER-RESOURCE CONSULTANTS

June 5, 2008 Ms. Kathryn Pounder, MA, MCIP, RPP Niagara Escarpment Commission 232 Guelph Street Georgetown, Ontario L7G 4B1 Subject: Peer review of Duntroon Quarry hydrogeologic modelling: Report #1

Dear Ms. Pounder: We have conducted a preliminary review of the groundwater modelling conducted for the proposed expansion of the Duntroon Quarry, Clearview Township, County of Simcoe. For our preliminary review we have studied the reports of the modelling and assembled a set of questions and comments that we hope will clarify the analyses of current conditions, and enable us to understand fully the work that has been conducted in anticipation of the predictive scenarios. We expect that in some instances our comments will require a simple response directing us to other parts of the extensive documentation for the application. Our preliminary review is presented in two parts:

? Overview comments; and ? Detailed technical comments/questions. For our final review, we will review the results of the predictive analyses in detail, and examine the model input and output files. Since we do not have access to the computer code that has been used for the updated modelling (MODFLOW-SURFACT), we expect that the final part of our review may require meeting with the modellers of Jagger Hims Limited.

90 FROBISHER DRIVE, UNIT 2B, WATERLOO, ON, N2V 2A1 ? TEL: (519) 579-2100 ? FAX: (519) 579-9779 WWW.

S. S. PAPADOPULOS & ASSOCIATES, INC.

Environmental & Water-Resource Consultants

To: Ms. Kathryn Pounder, MA, MCIP, RPP

Page: 2

I. Overview

The reporting of the groundwater modelling has been submitted in two parts:

? Jagger Hims Limited, 2005: Duntroon Quarry Expansion: Geological Report and Level 2 Hydrogeological Assessment, Lot 25 and Part Lot 26 Concession 12 and Part Lot 25 Concession 11, Clearview Township, County of Simcoe, prepared for Georgian Aggregates and Construction Inc., September 2005. [The groundwater model is documented in Appendix F]; and

? Jagger Hims Limited, 2007: Duntroon Quarry Expansion: Level 2 Hydrogeological Assessment Addendum, Proposed Expansion and Proposed MAQ Highland Quarry, Computer Groundwater Modelling, Response to Agency Review Comments, prepared for Walker Aggregates Inc., October 2007.

We obtained these documents by downloading files from the Walker Industries Holdings Limited web site (). Some of the pieces of the 2005 report that are relevant to our review were missing, and Jagger Hims Limited (JHL) supplied them immediately. In particular, the missing pieces were Figures 6-11 and 6-22, and the tables in Appendix F.

Mr. Andrew G. Hims, P.Eng., during a brief conversation regarding the electronic reports, indicated that the analyses described in the 2007 addendum build on the 2005 analyses. Based on our review of the two documents, it is clear that a significant additional effort has been undertaken. The analyses have been revised substantially. We note the following changes in the 2007 analyses:

1. The distribution of the specified recharge has been modified based on a reassessment of the karst features at the site;

2. The distribution of hydraulic conductivity has been revised; 3. The water level targets for the calibration to existing conditions have been supplemented

with data from the proposed MAQ Highland Quarry; 4. The examination of the match between observed and calculated water levels for the

calibration to existing conditions has been expanded; 5. Flow observations have been incorporated in the evaluation of the simulation of existing

conditions; 6. The analysis has been extended to consider seasonal water level data rather than only

long-term average conditions; and 7. The predictive scenarios consider the cumulative impact of the proposed MAQ Highland

Quarry.

S. S. PAPADOPULOS & ASSOCIATES, INC.

Environmental & Water-Resource Consultants

To: Ms. Kathryn Pounder, MA, MCIP, RPP

Page: 3

In our opinion, the analyses generally have been conducted at a relatively high technical level that is consistent with the state-of-the-practice. During calibration of the model for existing conditions a close match has been obtained to some of the observations. However, based on our review of the calibrated model we do have reservations regarding its application for future conditions. We are not sure how well the analysis of existing conditions has been constrained by the available data. Furthermore, we are not clear about key elements of the analysis of existing conditions. Our reservations and requests for clarification and selected additional results are presented in the following detailed technical comments.

S. S. PAPADOPULOS & ASSOCIATES, INC.

Environmental & Water-Resource Consultants

To: Ms. Kathryn Pounder, MA, MCIP, RPP

Page: 4

II. Detailed technical comments/questions

1. It is not clear how well the distributions of hydraulic conductivity that have been inferred from model calibration are constrained by the available data from hydraulic testing. In the 2005 modelling, relatively simple distributions of hydraulic conductivity are considered (Figures F-5, F-6 and F-7). In contrast, the hydraulic conductivity distributions adopted for the 2007 modelling show a significant amount of detail. The reporting does not allow us to assess whether this detail is supported by the results of hydraulic testing, or whether it has been invoked in an ad-hoc manner solely to improve the matches to observed water levels on a well-by-well basis.

In our opinion, the connection between the results of testing and the inferences from calibration needs to be strengthened. We recommend that maps be produced that correspond to Figures A-1 through A-4 of the 2007 report, with the estimates of hydraulic conductivity estimated from in-situ tests superimposed on the most recent interpretation of the distribution of material properties.

2. It is not clear from the reporting whether hydraulic conductivity estimates are available from slug tests conducted on all of the monitoring wells on the Walker lands (existing quarry and expansion footprint) and the site of the proposed MAQ Highland Quarry. Are these data available? If they are, we recommend that they be included in the maps recommended in Point #1.

3. It is not clear how well the calibrated model is able to match the results of controlled pumping tests conducted in the vicinity of the site. Pumping tests are discussed in JHL (2005; p. 40-46). We expect that most of these tests provide only a local impression of material properties, and may therefore be valuable additions to a compilation of the results of single-well testing. Our real interest is in tests that may have stressed a larger area, such that the observations might be appropriate for testing the calibrated model. Are any of the pumping tests suitable for this purpose?

It is indicated on Page F-7 of JHL (2005) that pumping tests are typically "about an order of magnitude greater than packer testing results for the same aquifer." Is this suggestion based on results from the site, or from more general experience?

S. S. PAPADOPULOS & ASSOCIATES, INC.

Environmental & Water-Resource Consultants

To: Ms. Kathryn Pounder, MA, MCIP, RPP

Page: 5

4. The model documentation refers to anisotropy of horizontal hydraulic conductivity (JHL, 2005; p. F-20). Are any maps available that indicate interpreted preferential directions of jointing and/or dissolution channels in the vicinity of the site? A horizontal anisotropy ratio of 1.67:1 is indicated on Table F-7. In our opinion, this is a subtle ratio. Can a ratio this low be inferred reliably from the calibration? Are sufficient data from hydraulic tests available to support this inference? Is there evidence that supports the assumption that the principal directions of hydraulic conductivity follow the north-south alignment of the finitedifference grid?

5. Insufficient information on the calibrated model is provided to develop independent calculations of key quantities such as the inflow to the existing quarry. In particular, we request that additional maps be prepared of the thicknesses of each model layer. These maps should include a posting of the points used to constrain the mapping.

6. The representation of the seepage face along the Niagara Escarpment is described briefly in JHL (2005; Page F-7). It is indicated that groundwater discharges from the lower section of the aquifer (Amabel Formation + Fossil Hill Formation). This is consistent with the modelling approach described on Page F-16, in which drain nodes are assigned control levels that correspond to the interface between the Fossil Hill Formation and the Cabot Head Formation. This approach is not consistent with our experience at other sites along the Niagara Escarpment. Our experience at sites in southern Ontario suggests that seepage faces form at the contact between the overburden and the Amabel Formation, at discrete depths within the Amabel Formation, and at the base of the Amabel Formation. Our experience is illustrated in Figure 1, and is consistent with the theoretical and experiment results of Rulon and Freeze (1985) and Rulon and others (1985). Is there evidence from the site that the only seepage from the escarpment is at its base? Elsewhere in southern Ontario, lines of ice that form along the walls of rock cuts and quarry walls provide visual evidence of multiple seepage faces, as do accumulations of vegetation. Have seepage faces been mapped along the face of the Escarpment?

The effect of specifying drains with a control level only at the base of the Fossil Hill is a tendency of the model to predict relatively low groundwater levels and discharge rates along the Escarpment. This tendency appears to be corroborated in the updated model of existing conditions; in particular, a zone of relatively low hydraulic conductivity has been added parallel to the Escarpment in model layers 1 and 2 to keep water levels high. Is this zone of reduced hydraulic conductivity supported by data from hydraulic tests?

7. A similar approach is adopted to represent the quarry. The control levels for the drains that represent the existing quarry are set at the base of the quarry. Have seepage faces been mapped in the existing quarry?

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