Karst Investigation of the Duntroon Quarry Expansion Lands

Transcription

1 Karst Investigation of the Duntroon Quarry Expansion Lands October 3, 2007 Prepared for: Jagger Hims Limited Prepared by: Marcus J. Buck, Marcus J. Buck Karst Solutions Dr. Stephen R.H. Worthington,

2 Executive Summary and Marcus J. Buck Karst Solutions carried out a detailed field investigation and assessment of karst development at the Duntroon Quarry expansion lands and in the vicinity. The work builds on the hydrogeological work already completed by Jagger Hims Limited and is intended to supplement their report. As a result of a regional survey, a variety of karst features were identified in an area that extends approximately 2 km to the north and 2 km to south of the expansion property. Between these limits and within 700 to 1400 m of the Niagara Escarpment there is either an absence of surface streams or the surface streams sink. To the west of this area there are surface streams that flow to the west, though there are some sinking streams as well. In the area studied, 74 springs were found that discharge from the Amabel aquifer. The majority of these discharge along the Niagara Escarpment where they are found at the head of streams that descend the Niagara Escarpment slope. These streams often sink on reaching an erosional bench on top of the Manitoulin Formation, and 57 springs were found discharging from the Manitoulin Formation at a subsidiary escarpment bordering the Manitoulin bench. The Amabel and Manitoulin springs are typical of springs elsewhere along the Niagara Escarpment, with the larger springs having mean flows of several litres per second. Four tracer tests were carried out from sinking streams, two of which were on the Amabel plateau and two on the Manitoulin bench. The results were generally similar, with the fastest groundwater pathways to springs having velocities ranging from 500 to 3500 m/day, which is typical of velocities between sinking streams and springs in karst aquifers. Local-scale investigations were carried out on the expansion lands. This work included continuous water level monitoring at three wells, electrical conductivity and temperature profiling at four wells, tracer testing from four wells to a nearby spring, and continuous monitoring of stage and electrical conductivity at that spring. The tracer testing from the wells gave velocities that ranged from 4 m/day to 1500 m/day, which is typical for tracer tests in karst aquifers when the tracer injections are into boreholes. Calculations show that this corresponds to fracture apertures that ranged from <0.05 mm to 3.7 mm along the traced pathways from the boreholes to the spring. Electrical conductivity and temperature profiling showed abrupt changes at specific horizons in the boreholes, suggesting preferential flow along a limited number of horizons in each well. Marcus J. Buck Karst Solutions Page i

3 A conceptual model of the aquifer was attained from the above measurements, together with observations in Duntroon Quarry and borehole measurements reported by Jagger Hims Limited (2005, 2007b). The uppermost few metres of bedrock are highly weathered. Below this, the weathering is focussed on a limited number of fractures, typically producing enlargements up to several millimetres in size. Openings may be substantially larger along the flow paths between sinking streams and springs, as well as in the vicinity of the larger springs. Jagger Hims Limited (2005, 2007a) has anticipated that recharge (injection) wells close to the quarry may be necessary to mitigate the lower groundwater levels predicted in the surrounding areas as a result of quarrying. With the distributed percolation recharge to the aquifer in the expansion lands, it is concluded that many small channels and only a much smaller number of conduits (i.e., with a diameter > 1cm) will be encountered during quarrying, and that the modelling by Jagger Hims Limited provides a good representation of the likely discharges. Conduits are most likely to be encountered in the area closest to the largest springs (SW2A and SW2B) where localized grouting might be required if inflows to the quarry become problematic. The proposed quarries on either side of Grey County Road 31 (i.e., Highland Quarry and Duntroon Quarry expansion) have the potential to impact the SW2 springs located at the southwest corner of the Duntroon expansion lands. These springs derive their groundwater recharge from a catchment area that may extend across portions of each of the proposed quarries. Conversely, impacts on springs along the Niagara Escarpment are likely to be minor. Some of the excess water from dewatering of the quarry will be discharged to the SW9 watercourse. This is a sinking stream located on the Amabel plateau on land owned by Walker Aggregates Inc. to the east of the proposed extraction area. Groundwater tracing indicates that this stream flows rapidly in the subsurface and resurges at 19 springs located along the Niagara Escarpment. The quarry discharge water would represent only a small fraction of the existing maximum flows in the creek and would help sustain flow in the creek and at the springs. The net mean discharge at the springs would be little changed during the period that the quarry is dewatered. Acknowledgements We would like to thank the private property owners that kindly permitted us to conduct fieldwork on their lands. We are especially grateful to Bill Franks and his family and to Victor and Emily Smidor for their hospitality while conducting the fieldwork. Marcus J. Buck Karst Solutions Page ii

4 Table of Contents Executive Summary... i Acknowledgements... ii Table of Contents... iii List of Tables... v List of Figures... vi 1.0 Introduction Objectives and Scope Report Structure Synthesis Nature of Karstification in the Duntroon Quarry Area Regional Patterns of Aquifer Recharge and Discharge Regional-scale Tracer Testing from Sinking Streams Local-scale Investigations Karstification in the Bedrock Aquifer at the Duntroon Quarry Expansion Lands Karst Issues Relevant to Quarrying at the Duntroon Quarry Expansion Lands Use of Groundwater Recharge Wells Influence of Karst Conduits on the Drawdown Zone Potential Impacts to the SW2 Springs Potential Leakage between the Proposed Quarries Potential Impacts to Niagara Escarpment Springs Discharge of Quarry Water to the SW9 Watercourse Study Methodology Karst Study Area Field Mapping and Surface Water Monitoring Climate Monitoring Borehole Monitoring Groundwater Tracing Regional Investigation of Karst Regional Karst Geomorphology and Hydrology Karst Development on the Amabel Plateau Observations at the Camarthen Wetland Tributary and Nearby Springs Karst Development on the Manitoulin Bench Measurements of Streamflow around the Study Area Perimeter Marcus J. Buck Karst Solutions Page iii

5 5.0 Investigation at the Manitoulin Bench Site Description Results of the Groundwater Trace from Site Investigation of the SW9 Watercourse and its Resurgences Site Description Streamflow Losses along the SW9 Watercourse Results of the Groundwater Trace from the SW9 Watercourse Results of the Groundwater Trace from SW Investigation of the SW28 Watercourse and its Resurgences Site Description Results of the Groundwater Trace at SW Investigation at the Duntroon Quarry Expansion Lands Water Level Data from BH02-1, BH02-4 and BH Investigations in the Vicinity of the SW2 Springs Site Description Monitoring Data at the SW2A Spring and Nearby Boreholes Recharge for the SW2 Springs Groundwater Tracing to the SW2A Spring Conclusions References Cited Figures Appendix A: Glossary of Karst Terms Appendix B: Photographs Appendix C: Classification and Description of Features Appendix D: Surface Water Data Appendix E: Groundwater Tracing Data Marcus J. Buck Karst Solutions Page iv

6 List of Tables Table 1. Classification of features inventoried during the field investigation of karst...18 Table 2. Number and size of springs and spring groups that occur in each aquifer...21 Table 3. Observed utilizations of springs...23 Table 4. Karst basins identified on the Amabel plateau...24 Table 5. Surface water monitoring data for SW26 and the nearby springs on May 15 and November 17, Table 6. Total discharge (L/s) measured from selected Amabel and Manitoulin springs during high and low flow conditions...33 Table 7. Surface water data measured at the Manitoulin escarpment on April 19, Table 8. Surface water sites where the tracer was recovered from the SW9 watercourse tracer test...44 Table 9. Approximate residence times calculated for the ephemeral pond at Site 7 during the groundwater trace...52 Table 10. Surface water data measured at selected sites on May 10, Table 11. Variations in the relative contribution of sinking stream recharge to total discharge at the SW27 spring group...55 Table 12. Groundwater monitor details for monitoring wells located near the SW2A spring...59 Table 13. The calculated surface area of the springshed for the SW2 springs...62 Table 14. Details of the tracer tests at the SW2A spring on May 12, Marcus J. Buck Karst Solutions Page v

7 List of Figures Figure 1. Regional map of karst features and surface water monitoring sites...72 (fold-out map in back pocket) Figure 2. Discharge by magnitude of 46 gauged springs in the Amabel Formation and 42 gauged springs in the Manitoulin Formation...72 Figure 3. Map of Niagara Escarpment springs located north of County Road Figure 4. Figure 5. Figure 6. Figure 7. Figure 8. Figure 9. Uranine dye concentrations at springs located below the Manitoulin Formation following the injection at Site 114 on April 19, Map illustrating tracing results at springs located below the Manitoulin Formation following the injection at Site 114 on April 19, Map illustrating tracing results at various Niagara Escarpment springs following the injection in the SW9 watercourse on April 23, Stream flow measured along the SW9 watercourse downstream from SW9 on April 25, Map illustrating tracing results at Niagara Escarpment springs located north of County Road 91 following the injection in the SW9 watercourse on April 23, Uranine dye concentrations in the two creeks that flow into Franks Pond following the tracer injection in the SW9 watercourse on April 23, Figure 10. Uranine dye concentrations at two Amabel springs at Sites 114 and 116 following the tracer injection in the SW9 watercourse on April 23, Figure 11. Phloxine dye concentrations in the two watercourses that flow into Franks Pond following the tracer injection at SW10 on April 23, Figure 12. Map illustrating tracing results at various Niagara Escarpment springs following the injection in the SW28 watercourse on May 10, Figure 13. Map of the SW27 spring group...83 Figure 14. Uranine dye concentrations at Site 46/47, located just downstream of the SW27 Spring Group, following the injection in the SW28 watercourse on May 10, Figure 15. Water levels in Wells BH02-1, BH02-4 and BH03-9 from May 11 to October 28, Marcus J. Buck Karst Solutions Page vi

8 Figure 16. Correlation between daily precipitation at the Duntroon Expansion property with water levels in the BH03-9 Well from May 11 to October 28, Figure 17. Map of the SW2 springs and nearby monitoring wells...86 Figure 18. Spring discharge at the SW2A spring from April 14 to October 28, Figure 19. Electrical conductivity and temperature at the SW2A spring from April to October, Figure 20. Water levels at the SW2A spring and adjacent wells from April to October, Figure 21. Electrical conductivity and temperature profiles at the TW04-1 Well on May 12 and May 26, Figure 22. Electrical conductivity and temperature profiles at the TW04-2 Well on May 12 and May 26, Figure 23. Electrical conductivity and temperature profiles at the TW04-3 Well on May 12 and May 26, Figure 24. Electrical conductivity and temperature profiles at the BH03-9 Well on May 12 and May 26, Figure 25. Electrical conductivity and temperature profiles at Wells BH03-9, TW04-1, TW04-2, and TW04-3 on May 12 and May 26, Figure 26. Tracer concentrations at the SW2A spring following dye injections at Wells BH03-9, TW04-3, TW04-1 and TW04-2 on May 12, Marcus J. Buck Karst Solutions Page vii

9 1.0 Introduction In September 2005, Jagger Hims Limited completed a geological report and Level 2 hydrogeological assessment as technical support for the application to license the Duntroon Quarry expansion lands under the Aggregate Resources Act for extraction as a Category 2 quarry. The expansion lands are on the north side of Simcoe Road 91, or adjacent to the existing quarry but on the opposite side of the road. The report provides an assessment of the geology, groundwater and surface water resources in the vicinity of the existing quarry and the expansion lands. During their field investigations, karst features were identified that are described in Section of their report. This raised questions regarding the influence of karst in the area and the implications this may have on the proposed quarry with regards to potential impacts to local groundwater and surface water resources. and Marcus J. Buck Karst Solutions have undertaken a field investigation and assessment of karst development that began in the fall of 2004 and continued through 2005; this report is the result of that investigation. The karst study builds on the hydrogeological work already completed by Jagger Hims Limited and is intended to supplement their report. As such, their results are not reiterated here except where relevant to the discussion of karst. 1.1 Objectives and Scope The principal objectives of the karst study are to: 1. Characterize the karst in the vicinity of the proposed quarry expansion. 2. Define the role that the karst plays in the regional hydrogeology. 3. Evaluate the potential for adverse impacts from the proposed quarry expansion to groundwater and surface water resources and their current uses, and to recommend measures to minimize and mitigate such potential impacts. The following tasks were included in the scope of work: 1. Field mapping of key karst features in the study area, including dolines, sinking streams and springs. 2. Measurements of flow at sinking streams and discharge from springs during high flow in spring and low flow in summer or fall. Marcus J. Buck Karst Solutions Page 1

10 3. Groundwater tracer studies from four sinking streams as well as under natural flow conditions from four boreholes. 4. Borehole testing at six boreholes, including continuous monitoring of water level, and electrical conductivity (i.e., specific conductance) profiling. Concurrent with the borehole testing, a nearby spring was monitored continuously for water level, electrical conductivity and temperature. 1.2 Report Structure Following the introduction, a synthesis of the results of the karst investigation is presented. The study methods are summarized in Section 3. Section 4 presents the results of a regional study of karst that are based primarily on field mapping and surface water monitoring at the sinking streams and springs. This provides the framework for understanding the development of karst regionally. Sections 5 to 8 present the results of more detailed work carried out at specific sites: a groundwater trace at the Manitoulin bench (Section 5), a groundwater trace at the SW9 watercourse (Section 6), a groundwater trace at the SW28 watercourse (Section 7) and groundwater tracing and borehole testing on the Duntroon expansion property (Section 8). These detailed studies test the interpretations of karst development identified during the regional study. Section 9 is the conclusions. All figures are presented at the end of the report, before the Appendices. A glossary of karst terms used in the text is provided in Appendix A. All photographs referenced in the text are presented in Appendix B. The data prepared from the inventory of karst features, surface water monitoring and groundwater tracing are provided in Appendix C, D and E, respectively. 2.0 Synthesis 2.1 Nature of Karstification in the Duntroon Quarry Area It has been known for a long time that some limestone and dolostone aquifers become karstified, a process by which interconnected solutionally-enlarged fractures develop within them. This results in increased secondary permeability and more rapid groundwater flow. However, it is only in recent years that tools have become available that allow karstification to be modelled and its extent predicted. The first breakthrough was the discovery of non-linear kinetics; that dissolution rates slow remarkably as the calcium and magnesium carbonate concentrations Marcus J. Buck Karst Solutions Page 2

11 approach equilibrium with calcite and dolomite. These results allowed the evolution of karst to be modelled, and the models showed that karstification occurs in all unconfined carbonate aquifers (Dreybrodt, 1996). In recent years, sophisticated numerical modelling with large grids has shown that sparsely fractured rock, low hydraulic gradients, low CaCO 3 concentrations in water recharging the aquifer, and the occurrence of sinking streams all promote the development of focussed flow within a smaller number of larger conduits. Conversely, highly fractured rock, high hydraulic gradients, high CaCO 3 concentrations in water recharging the aquifer, and the occurrence of percolation recharge with no sinking streams all promote the development of a distributed pattern with a larger number of channels and smaller conduit sizes in the bedrock (Romanov et al., 2003, 2004; Dreybrodt et al., 2005). Of these factors the type of recharge (percolation or sinking stream) is probably the most important. The numerical modelling to date has assumed limestone rather than dolostone bedrock; the slower dissolution of dolomite as compared to calcite suggests that the tendency towards distributed channel patterns with many channels and smaller conduit sizes will be accentuated in a dolostone aquifer. The implications for the Duntroon Quarry area are that there should generally be a distributed pattern of many small conduits because most aquifer recharge is from percolation rather than concentrated sinking stream recharge. The solution channels should form an integrated network and this imparts a relatively high hydraulic conductivity to the aquifer. The channel network discharges to the surface at numerous small springs. In the locations where there is sinking stream recharge, there should be the tendency for fewer but larger conduits and larger springs or spring groups. 2.2 Regional Patterns of Aquifer Recharge and Discharge A regional study of karst features and spring flow was made in order to understand the patterns of recharge to and discharge from the Amabel aquifer (see Section 4 for full details). The southern limit of the field investigation was at 21/22 Sideroad, although a few observations were also made at the Mad River valley at Devil s Glen, some 4 km to the south of the site. The northern limit was the edge of the Pretty River valley, some 2 km north of the site. Between these limits and within 700 to 1400 m of the Niagara Escarpment there is either an absence of Marcus J. Buck Karst Solutions Page 3

12 surface streams or the surface streams sink. Thus, this is typical for karst terrain along the Niagara Escarpment. There are six enclosed drainage basins in this area, with the largest having an area of 119 hectares. To the west of this area there are surface streams with flow to the west, though there are some sinking streams as well (Section 4.2). In the local setting, there are two erosional escarpments located within the geographical extent of the Niagara Escarpment. The Amabel and Manitoulin Formation dolostones act as the erosionresistant cap rocks that mark their crests. Thus, the escarpments are referred to here as the Amabel and Manitoulin escarpments. Furthermore, the distinct erosional bench that often occurs on top of the Manitoulin Formation is referred to as the Manitoulin bench, and this forms a distinct landform that separates the overlying Amabel escarpment from the Manitoulin escarpment. As referenced in the text or illustrated in figures, the crest of each escarpment is defined by the sharp break in slope that often occurs above the steepest part of each escarpment slope. The two escarpments acts as important landmarks for understanding regional groundwater flow patterns. In the area studied, 74 springs were found that discharge from the Amabel aquifer, with the largest having mean discharges of several litres per second (Section 4.1). Many of the streams descending the Amabel escarpment slope are fed primarily by discharge from the Amabel aquifer. These spring-fed streams often sink on reaching the Manitoulin bench. A total of 27 sinking streams were recorded on the Manitoulin bench and 57 springs located along the Manitoulin escarpment slope drained the Manitoulin Formation with the largest having mean discharges of several litres per second (Section 4.1). Roughly half of the Amabel and Manitoulin springs have mean discharges ranging from 0.3 to 3 L/s. The remainder are larger or smaller, with the largest having mean discharges up to about 10 L/s. The size distribution of the springs is typical of the Niagara Escarpment, although a few larger springs are known elsewhere on the Niagara Escarpment. The enclosed drainage basins and sinking streams provide evidence that karst has developed in the underlying bedrock of the Amabel Formation. In the case of the Manitoulin Formation, the observations of karst development along the Manitoulin bench suggests that the formation Marcus J. Buck Karst Solutions Page 4

13 becomes karstified where the formation outcrops at the surface or where the overburden is sufficiently thin to permit groundwater infiltration. 2.3 Regional-scale Tracer Testing from Sinking Streams Four tracer tests were carried out from sinking streams, two of which were on the Amabel plateau and two were on the Manitoulin bench (Table E-1). Full details are given later in this report in Sections 5, 6, and 7. The results were generally similar, with the fastest groundwater pathways to springs having velocities ranging from 500 to 3500 m/day. These velocities are typical of tracer test velocities in karst, as a compilation of 2877 tracer tests in karst in 31 countries gave a median velocity of 1900 m/day (Worthington et al., 2000). The tracer was detected at multiple springs in each of the four tracer tests. The tracer test from the SW9 watercourse, which is at the east end of the expansion property, was the longest trace with flow paths through the Amabel Formation ranging from 400 m to 700 m. The trace also had the largest number of positive detections at springs (19 sites). Most of the tracer was recovered at the SW11 springs. At the time of the tracer test, the SW9 watercourse accounted for 43% of the flow resurging at the SW11 springs, with the remainder being derived from percolation recharge. During summer, the SW9 watercourse dries up and all of the discharge from the SW11 springs is from percolation recharge. The tracer test from the SW28 watercourse, a smaller sinking stream, showed a flow path through the Amabel Formation extending 300 m to four individual springs within a spring group at Site SW27, located at the Niagara Escarpment to the east. A series of measurements under a variety of flow conditions indicated that the SW28 watercourse accounted for 0% to 50% of the flow resurging at the SW27 spring group, with the remainder being derived from percolation recharge. As the flow in the SW28 watercourse increased, its relative contribution to the discharge at the SW27 spring group also increased. Although flow from sinking streams accounted for a significant proportion of the flow to a number of springs, at least during springtime, most recharge to the majority of Amabel springs was from percolation recharge. Flow measurement data for the Manitoulin bench suggest that percolation recharge is also important to many of the Manitoulin springs, although groundwater Marcus J. Buck Karst Solutions Page 5

14 tracing was not conducted to verify this. In the case of the tracer test from Site 114, the sinking streams roughly accounted for all of the discharge from the closest springs at the Manitoulin escarpment. 2.4 Local-scale Investigations Local-scale investigations were carried out at several locations on the Duntroon Quarry expansion property. Full details are given later in this report in Section 8. Several investigations were carried out in the southwest corner of the expansion property where there are four boreholes within 40 m of the SW2A spring. In addition, continuous water level measurements were made in three boreholes and at the SW2A spring to determine the magnitude and lag of short-term variations in water levels. Water level variations of up to a few centimetres were recorded, with lag of a few hours after rain events, showing that there is rapid percolation recharge to the aquifer. Variations in electrical conductivity at the SW2A spring reflected the rapid recharge as well as the flushing out of long residence time matrix water. Vertical profiles at the four boreholes showed abrupt changes in electrical conductivity and temperature at specific depths in all four boreholes, reflecting flow into or out of the boreholes at specific horizons. These presumably reflect flow along solutionally-enlarged bedding planes (Figures 21-25). Natural gradient tracer testing from the four boreholes to the nearby spring revealed groundwater velocities that ranged from less than 4 m/day to 1500 m/day. Calculations show that this corresponds to fracture apertures from less than 0.05 mm to about 4 mm along the traced pathways from the boreholes to the spring. 2.5 Karstification in the Bedrock Aquifer at the Duntroon Quarry Expansion Lands The upper few metres of the bedrock at the existing quarry and in wells at the expansion property is fractured and subsequently weathered by dissolution to give a weathered zone. At the existing quarry it is shown by a high frequency of horizontal and vertical fractures in the top 1 to 3 m or more, with the fractures often showing solutional enlargement and evidence of weathering, including oxidation of iron minerals (Photo 21). In boreholes it is shown by low core recovery and low rock quality designation (RQD) in the top several metres of bedrock. Marcus J. Buck Karst Solutions Page 6

15 Below the top few metres the karstification is less apparent. In some boreholes there are low core recoveries and low RQD at various depths throughout the Amabel, though these are an indication of fracturing and not necessarily karstification. Lost circulation is a better sign of karstification and this was noted in five boreholes on the expansion property, where it occurred at depths of 0.2 to 9.7 m below the top of the bedrock (Jagger Hims Limited, 2005). Abrupt changes in temperature or electrical conductivity, as measured on profiles in the boreholes, occur at a number of horizons throughout the Amabel, and are also an indicator of preferential flow (Section 8.2.2). The tracer testing from the four boreholes to the SW2A spring indicates fracture apertures up to about 4 mm. These small apertures are typical of karst aquifers, where most boreholes intercept open, solutionally-enlarged fractures with apertures of mm, and where few boreholes intercept fractures that are larger, or where all the apertures are smaller. Since the recharge in the expansion property is predominantly by widespread percolation, a distributed pattern of many small channels and conduits is predicted, and the studies carried out support this model. The implications are that predictions of flow in the aquifer, such as the modelling by Jagger Hims Limited (2005, 2007a), are likely to be accurate at a large scale, such as for predicting overall flow to the quarry or to the escarpment. However, model predictions for transport are unreliable in karst (Scanlon et al., 2003), so the model should not be relied on for estimates of travel times. 2.6 Karst Issues Relevant to Quarrying at the Duntroon Quarry Expansion Lands Use of Groundwater Recharge Wells Jagger Hims Limited (2005, 2007a) has anticipated that recharge (injection) wells close to the quarry may be necessary to mitigate the lower groundwater levels predicted in the surrounding areas as a result of quarrying. The performance of such wells in a karstic aquifer is a function of the nature of karstification. With the distributed percolation recharge to the aquifer in the expansion lands, it is anticipated that many small channels and only a much smaller number of conduits (i.e., with a diameter > 1cm) will be encountered. Marcus J. Buck Karst Solutions Page 7

16 The diameter of conduits is expected to increase in a downgradient direction as groundwater flow converges towards a spring. Thus, the largest apertures are expected near springs. The expansion lands span a natural groundwater divide between flow eastward to springs along the Niagara Escarpment and flow westward to the Beaver River. The western half of the expansion lands also span a local groundwater divide between flow to the northwest and to the southwest to wetlands and creeks that join the Beaver River. Consequently, conduit apertures throughout much of the expansion lands are likely to be small. The largest conduits are likely to be found immediately upgradient from the largest spring, SW2A. Consequently, this area has the largest probability of substantial return flow to the quarry from recharge wells. However, if the return flow were excessive then this could be reduced by localised grouting Influence of Karst Conduits on the Drawdown Zone The presence of conduits converging towards the SW2 springs may have the effect of extending the influence of the drawdown zone around either of the proposed quarries (i.e., Highland Quarry or the Duntroon Quarry expansion). The conduit networks surrounding each spring strongly influence the groundwater elevations within their springsheds. However, this effect should be largely limited to the extent of the springshed for each of the two springs. The springshed for the SW2B spring is entirely contained within the expansion property. Therefore, drawdown effects should not be exacerbated outside of the proposed quarry as a result of conduits there. On the other hand, the SW2A springshed extends to either side of Grey County Road 31. Within its springshed, the SW2A spring clearly acts as the local base level as indicated by the water elevations observed in the nearby boreholes. As groundwater flow diminishes during the dry season, the groundwater elevations converge towards the elevation of the spring. If only one of the proposed quarries proceeds, then the drawdown effects will likely be propagated along conduits across Grey County Road 31. In this case, injection wells may not be effective at maintaining water levels and localized grouting may be required. However, if both quarries proceed, then the conduits should not exacerbate drawdown effects because the influence of the conduits leading to the SW2A spring should not extend outside of the SW2A springshed, and the springshed is entirely contained within the two proposed quarry properties. Marcus J. Buck Karst Solutions Page 8

17 2.6.3 Potential Impacts to the SW2 Springs The SW2B spring and its springshed are entirely contained within the proposed Duntroon Quarry expansion. Therefore, this spring will be completed removed as a result of quarrying and will no longer contribute flow to the surface watercourse at SW2. The proposed quarries on either side of Grey County Road 31 (i.e., Highland Quarry and Duntroon Quarry expansion) also have the potential to impact the SW2A spring. This spring derives its groundwater recharge from a catchment area that extends across portions of each of the proposed quarries. Therefore, quarrying on either side of Grey County Road 31 at either of the proposed quarries will lead to loss of recharge for the SW2A spring. Furthermore, quarrying at either of the proposed quarries may lead to complete loss of discharge from the SW2A spring as a result of the diversion of groundwater flow along conduits intersected by quarrying. In the case of the Duntroon Quarry expansion, the loss of spring discharge could be mitigated by discharging excess quarry water into Wetland Unit 6 of the Rob Roy PSW complex during dewatering, as proposed by Jagger Hims Limited (2005). Once the Duntroon Quarry expansion is complete and the quarry fills with water, the lake level will not be sufficiently high to permit seasonal flow into the SW2 watercourse. However, the final lake in the existing quarry will outflow seasonally into Wetland Unit 6 and any impacts to groundwater beneath the wetland will be buffered by the final lake in the existing quarry (Jagger Hims Limited, 2007a) Potential Leakage between the Proposed Quarries The conduits that currently convey groundwater to the SW2A spring may later create permeable pathways between the two proposed quarries (Highland Quarry and Duntroon Quarry expansion), if both quarries proceed. This could cause the final lake levels to equalize in elevation if there is excessive leakage. On the other hand, if the conduits are generally shallow (above 512 m a.s.l.), then there may be little leakage along the conduits between the final lakes. Localized grouting of the intervening bedrock or other mitigation measures might be required if excessive leakage between the quarries becomes problematic Potential Impacts to Niagara Escarpment Springs Impacts to the majority of springs along the Niagara Escarpment are likely to be negligible. With the exception of the SW27 and SW11 springs, the Amabel springs located near the Marcus J. Buck Karst Solutions Page 9

18 expansion property derive most of their recharge from widespread infiltration across a broad band of land adjacent to the top of the Niagara Escarpment. It is concluded that these springs will not exhibit any significant loss of discharge as a result of the proposed quarrying at the expansion lands. Only those springs located closest to the quarry will exhibit any reduction in discharge, and even these will still be maintained by percolation recharge. Furthermore, their recharge should be fully restored once lakes are established in the quarries. The SW27 and SW11 springs receive part of their recharge from sinking streams. As indicated by the groundwater tracing, the SW27 springs are the resurgences for the sinking stream at SW28, and during peak flows in the spring they receive much of their recharge from the sinking stream. However, the surface catchment for the SW28 watercourse is outside the expansion lands and will not be affected by the proposed quarry there. Therefore, there will not be any loss of sinking stream recharge at these springs. Furthermore, these springs will continue to be maintained by widespread percolation recharge. The springs most likely to be impacted by the proposed quarry expansion are the SW11 springs. These are the principal resurgences for the sinking stream located at the east end of the expansion property, the SW9 watercourse. Groundwater tracing indicates that after sinking, this stream flows rapidly in the subsurface and resurges at 19 springs located along the Niagara Escarpment, with roughly 90% of the flow resurging at the SW11 springs. Despite the significant component of recharge from the sinking stream, the SW11 springs receive an even greater contribution from widespread percolation recharge on the Amabel plateau, and it is this percolation recharge that maintains these springs throughout the dry season. Therefore, with respect to the proposed quarry at the expansion property, it can be concluded that even with a significant loss of flow in the SW9 watercourse as a result of quarrying, the SW11 springs will still be maintained by the percolation recharge Discharge of Quarry Water to the SW9 Watercourse Dewatering of the proposed expansion quarry will occur during extraction phases 1, 2, and 3. Jagger Hims Limited (2007a, Table 4-42) uses computer modelling to determine that the dewatering will reach an estimated maximum of 19.8 L/s during Phase 3, and that the maximum dewatering rate will be less than this with concurrent dewatering of the proposed Highland Marcus J. Buck Karst Solutions Page 10

19 Quarry. The quarry water will be used for operational needs and the excess will be discharged into tributaries of the west-flowing Beaver River as well as to the eastward-flowing SW9 watercourse, which provides flow to Batteaux Creek to the east. From monthly measurements at station SW9 between May 2003 and August 2007, the flow ranged from zero in the summer months to a maximum of 42 L/s on April 11, 2005 (Jagger Hims Limited, 2007b). On April 25, 2005, the flow was 39 L/s, and this water sank into the ground over a distance of 220 m. However, the watercourse extends for at least 250 m farther and it is clear that very occasionally there must be flows that are substantially more than 39 L/s. However, the monthly data show that flow is 7 L/s or less for more than 95% of the time. The water that sinks along the SW9 watercourse was traced to 19 sites with roughly 90% flowing to the SW11 springs, where at the time of the tracing it accounted for only 43% of the total discharge. The remaining discharge is from percolation recharge to the aquifer. The flow resulting from the sinking stream recharge would be reduced during the period that the quarry is actively dewatering. Thus, the addition of the order of 10 L/s to the creek from dewatering would help sustain flow in the creek as well as at the SW11 springs. This amount of water would represent only a small fraction of the existing maximum flows currently observed in the SW9 watercourse. The excess quarry water could also be used to maintain water levels in two unevaluated wetlands located along the watercourse, ANSI A and ANSI B, as may be required seasonally. Any loss in surface flow in the SW9 watercourse could be roughly balanced by the pumping of excess water from the dewatering operations into the SW9 watercourse. Thus the net mean discharge from the SW11 springs would be little changed during the period that the quarry is dewatered. Once the quarry is complete and fills with water, some of the excess water from the quarry will flow seasonally into the SW9 watercourse (Jagger Hims Limited, 2007a). Any minor thermal effects at the Amabel aquifer springs as a result of discharging excess quarry water into the SW9 watercourse would not affect downstream fisheries because after discharging from the springs the water temperature rapidly approaches surface temperature while flowing down the talus slope, and because the in-line pond on W. Franks property has a pronounced thermal impact that overwhelms any temperature effects farther upstream (Jagger Hims Ltd., 2007a, b). Marcus J. Buck Karst Solutions Page 11

20 3.0 Study Methodology Initial site visits were conducted by M. Buck and S. Worthington in A detailed field investigation was planned based on the initial observations and conducted from August 2004 to November Some of the field mapping, surface water monitoring and groundwater tracing was conducted in Nottawasaga Lookout Provincial Park. This work was conducted under a research permit issued by Ontario Parks (Central Zone). 3.1 Karst Study Area The detailed study area was defined based on the initial observations. This area encompasses the Niagara Escarpment extending northward from the 21/22 Sideroad to the Grey-Simcoe County line, including the adjacent lands above the Escarpment on the east side of the County line. Thus, the Niagara Escarpment was examined in detail between 2 km north and 2 km south of the expansion lands. 3.2 Field Mapping and Surface Water Monitoring Within the study area, field mapping was focused on areas where karst features are most likely to occur. The principal features mapped are dolines, sinking and losing streams, and springs. Small-scale features such as karren were not recorded. A group of dolines were observed close to the prominent cliff along the Niagara Escarpment north of Simcoe Road 91; however, a detailed inventory was not conducted here because these dolines are located beyond the influence of the proposed quarrying. All other key karst features were documented and these are classified and described in Appendix C. Generally, most features were located on a map using a handheld GPS receiver. The accuracy indicated by the unit was typically ± 5 to 12 m, and a few repeat measurements on different occasions were consistent with this reported accuracy. In forested areas, most measurements were taken during spring prior to the emergence of the forest canopy. This minimized interference and improved signal reception. More detailed ground surveys were conducted at a few locations where higher resolution mapping was required, specifically where groundwater tracing was conducted. The ground surveys were conducted with a Suunto compass and inclinometer and a fibreglass tape, and the surveys were Marcus J. Buck Karst Solutions Page 12

21 georeferenced with GPS measurements. The catchment divides for any surface drainage basins described in the text were defined by the surface topography as indicated by contours on 1:10,000-scale Ontario Base Maps. Two of the Jagger Hims Limited surface water monitoring sites, SW9 and SW28, are located along watercourses that are referred to repeatedly in the text. These small watercourses do not have names and are referred to as the SW9 and SW28 watercourses. Surface water measurements were made at watercourses and springs throughout the study area, and included measurements of flow, temperature and electrical conductivity. The specific methods and estimated accuracy for flow measurements are indicated in Appendix D. Temperature and electrical conductivity were measured using a WTB portable conductivity meter (Model 340i). The accuracy reported by the manufacturer is ± 0.1 C for temperature and ± 0.5% of the measured value for electrical conductivity. The conductivity was corrected to a reference temperature of 25 C. The measurements were conducted in April or May when flows were high, and were repeated during summer or fall when flows were at a minimum. Many of the springs are located at the head of the many small watercourses located along the Niagara Escarpment slope, and groundwater discharge was often observed over a distance of several metres to tens of metres. At many of these sites, temperature and conductivity were measured as close as possible to where the groundwater first emerges, but discharge was measured farther downstream to better determine the total discharge. In addition to measurements within the detailed study area, streamflow measurements were also conducted along the roads that encompass the perimeter of the study area, first on October 26, 2004, then again on May 16-17, These measurements were designed to identify any large springs outside of the detailed study area that might be relevant to the hydrogeology of the study area. All of the surface water monitoring locations are described in Appendix C and the measurement data are listed in Appendix D. Figure 1 (back pocket) is a regional map indicating the location of karst features and surface water monitoring points. However, due to scale effects, some of the features and monitoring points could only be illustrated on more detailed maps (Figure 3, 13 and 17). Each feature and surface water monitoring site was identified using a unique number between 1 and 226 (for example: Site 43 ). In cases where several interrelated features were located in close proximity, Marcus J. Buck Karst Solutions Page 13

22 a number was used to identify the group and lowercase alphabetic suffixes were used to distinguish the individual features. Similarly, the location of surface water monitoring sites located at the junction of two or more tributaries was identified with the same number but the measurements for each tributary were distinguished using alphabetic suffixes, such as e for east tributary. In a few cases where additional features were added, uppercase alphabetic suffixes were added to distinguish these additional locations. 3.3 Climate Monitoring Climate data were collected every two minutes from May 9 to November 18, 2005 using a Hobo Micro Station data logger. The weather station was mounted on a two-metre tripod and was located in a sizeable field near the east end of the expansion lands (UTM location, NAD27: m E., m N; Photo 20). The attached sensors recorded rainfall, solar radiation, temperature and relative humidity. The data were post-processed to calculate hourly means and total precipitation for one hour intervals and then again to calculate daily data. On October 2, the equipment was checked in the field and a bird nest (American robin) was discovered inside the top of the rain gauge. This was likely constructed shortly after the weather station was installed in May. As a result, the timing of precipitation events prior to October 2 should be accurate but the amount of rainfall recorded may be significantly reduced, and small precipitation events may not have been detected at all. Nevertheless, the timing of the larger rainfall events proved useful for comparison with groundwater discharge data at springs and water elevation records for boreholes. 3.4 Borehole Monitoring Water level measurements with a 15-minute frequency were made at BH02-1, BH03-9 and at the SW2A spring with Solinst Leveloggers, and at BH02-4 with a Heron Instruments Dipper-log. In addition, a Solinst Barologger was used for correcting for changes in atmospheric pressure. Campbell Scientific electrical conductivity/temperature probes and data loggers were used for borehole profiling and for monitoring the spring at SW2A. Marcus J. Buck Karst Solutions Page 14

23 3.5 Groundwater Tracing Groundwater tracing was conducted at four wells and at four sinking streams. For each injection at the wells, the dye (previously diluted into four litres of water) was injected by siphoning it down tubing to below the water table. A further 10 litres of groundwater from the nearby spring (SW2A) was flushed down the tubing to ensure that all the dye was flushed from the container and tubing, and a further 70 litres of water was added to each well to ensure that the dye was flushed into the bedrock. The amount of dye injected was pre-determined from two equations which give good predictions of tracer concentrations at springs (Worthington and Smart, 2003). At the sinking streams, all of the flow was observed sinking either at a doline or gradually into the channel beds. The tracers used were the fluorescent dyes uranine (also known as sodium fluorescein; Colour Index 45350) and phloxine B, Colour Index 45410). Both dyes have very low toxicity and are approved for use in drugs in Canada (Food and Drugs Act, Section C ). Water samples were collected at springs where the dye might flow to. Collection of water samples was either by hand or using an ISCO Model 3700C 24-bottle automatic water sampler. Samples were analyzed with a Turner Designs Picofluor filter fluorometer, which has two channels and can measure concentrations of two different dyes injected at the same time. The detection limit was found to be about 0.2 parts per billion for uranine and 0.8 parts per billion for phloxine B and was due to background concentrations of natural organic acids from decayed vegetation. Samples were analyzed on-site in near real time on a Turner Designs Picofluor filter fluorometer. The analysis on-site gave approximate results that were ideal for planning sample collection and subsequent tracer injections. After the completion of the tracer testing all samples were stored at 4 C and later re-analyzed on the filter fluorometer after equilibrating to room temperature for 24 hours. All groundwater tracing data are listed in Appendix E. The MOE was informed of the groundwater tracing program in advance. One trace was conducted within Nottawasaga Lookout Provincial Park and a permit was obtained from the Ministry of Natural Resources in advance to carry out this work. In addition, in areas where the tracing was conducted near residential properties, a letter was sent to the residents informing them of the planned groundwater tracing. Marcus J. Buck Karst Solutions Page 15

24 4.0 Regional Investigation of Karst The landscape within the study area is dominated by the Niagara Escarpment, an erosional escarpment that marks the east edge of a regional cuesta. The dolostone of the Amabel Formation forms the erosion-resistant cap rock of the cuesta and this dolostone often outcrops in cliffs at or near the brow of the escarpment. To the west, the cuesta surface slopes very gently to the southwest. For simplicity, the tablelands lying west of the Niagara Escarpment are referred to as the Amabel plateau. A prominent erosional bench has formed partway down the Niagara Escarpment slope on top of the dolostone of the Manitoulin Formation. It formed as a result of preferential erosion of the overlying shale of the Cabot Head Formation. The Manitoulin dolostone also forms an erosion-resistant cap rock that marks the crest of a smaller escarpment. Thus, the Niagara Escarpment is marked by two distinct erosional escarpments, the Amabel and Manitoulin, separated by the Manitoulin bench. The Amabel plateau and the Manitoulin bench are the focus of the karst study since these are the areas underlain by soluble carbonate bedrock. The Cabot Head Formation occurs between the Amabel and Manitoulin Formations. It is predominantly shale and is expected to act as an aquitard that isolates the two dolostone aquifers. The Manitoulin Formation is underlain by the Whirlpool Formation, a quartz sandstone that is about 2 m thick. The Whirlpool, in turn, is underlain by the Queenston and Georgian Bay Formations that consist largely of shales with interbeds of siltstone and carbonate. Any downward movement of groundwater will be negligible as a result of these thick sequences of shale with low permeability. Section 4.1 provides a general introduction to the types of karst features present in the study area. Sections 4.2 and 4.3 summarize the regional observations of karst development on the Amabel plateau and Manitoulin bench, respectively. Finally, Section 4.4 summarizes the results of flow measurements conducted around the perimeter of the study area. The remainder of the report focuses on specific areas where more detailed work was conducted. 4.1 Regional Karst Geomorphology and Hydrology Karst terrain is a landscape with distinctive hydrology and landforms arising from a combination of high rock solubility and well developed secondary permeability. Karst is most common in limestone, dolostone and gypsum, but can develop in any soluble rock. Solution of bedrock Marcus J. Buck Karst Solutions Page 16

25 creates a unique sculpturing of exposed bedrock surfaces with a variety of diverse forms, known collectively as karren. More importantly, solutional enhancement of fractures and bedding planes in the bedrock forms interconnected channels, conduits and caves that increase secondary permeability. These self-organizing channel networks form continuous paths to springs that potentially permit high flow velocities similar to those of surface streams. These subsurface channels have the capacity to transport sediment introduced with infiltrating water. Once channel networks are established, many of the typical features of karst can begin to form, such as dolines, sinking streams, dry valleys, closed depressions, caves and springs. It is the establishment of these interconnected channel networks that creates a karst aquifer. A karst aquifer is defined here is an aquifer with solutionally enhanced secondary permeability, chiefly characterized by rapid groundwater flow velocities and the occurrence of continuous flow paths along channels that direct groundwater flow from recharge areas to springs. Figure 1 (back pocket) is a regional map illustrating the distribution of karst features mapped in the area. As is common at many areas along the Niagara Escarpment, the prevalence of karst features is often greatest adjacent to the Escarpment brow where overburden is often thin and hydraulic gradients are steep. The entire plateau here is underlain by dolostone of the Amabel Formation, which is known to be highly susceptible to karstification (e.g., Cowell, 1978). There are few observations of karst development in the Fossil Hill Formation, the dolostone that directly underlies the Amabel. However, karst is developed in the lateral equivalent of the Fossil Hill at Waterdown, Ontario. There, the argillaceous dolostone of the Reynales Formation underlies the Amabel Formation and a karstic aquifer is well developed in both units (Ecoplans Limited, 2005). In the Duntroon area, the Fossil Hill Formation is not exposed at the surface and no direct observations were made. For simplicity, the aquifer within the Amabel and Fossil Hill Formation dolostones will be referred to collectively as the Amabel aquifer. The most prevalent karst features mapped in the study area are dolines, sinking streams and springs. Table 1 presents a classification of the karst features and lists their numbers. A more detailed classification is presented in Table C-1 in Appendix C. A general introduction to the karst features found locally follows: Marcus J. Buck Karst Solutions Page 17

26 Table 1. Classification of features inventoried during the field investigation of karst. N is the number of features associated with either the Amabel or the Manitoulin Formations. Feature N Amabel N Manit. Explanation Spring Relict, intermittent and perennial springs. Sinkpoint 7 0 Discrete point at which streamflow is lost at a doline, or at a discrete point along a watercourse. Sinking stream with discrete sinkpoint(s) Sinking stream that loses flow gradually along a losing reach 3 3 A watercourse that loses flow to the subsurface at a discrete sinkpoint, often at a doline A watercourse that loses flow to the subsurface by gradual infiltration along a losing reach. The infiltration likely occurs where the soil mantle is thin permitting recharge to the underlying karst aquifer. Dry valley 3 0 A relict fluvial valley that no longer has any surface flow, typically marked by dolines along its length. Suffosion doline 19 8 Doline formed in the soil mantle. Monitoring point (surface water) Springs utilized for water supply (dug well, cistern) Other uses of springs (ponds, pipes) Location at a pond or along a surface watercourse where discharge, temperature, electrical conductivity or fluorescence were measured. 7 4 A dug well utilizing well tiles or a cistern designed to collect spring water for use as a drinking water supply or for livestock. 6 0 Either an artificial pond constructed at a spring, or the presence of a plastic or steel pipe at a spring suggesting former use as a water supply. The intended use is generally unknown. Karren are the small-scale dissolutional features such as pits, runnels and solution grooves found on the dolostone surfaces. The observed karren show little relief, generally extending a few millimetres to a few tens of centimetres into the bedrock as is typical for the Amabel dolostone elsewhere in Ontario. These small-scale features were not mapped. Karren are present wherever dolostone is exposed, except in quarries and on some cliff faces where the dolostone has only recently been exposed. Observations suggest that there are relatively few exposures of dolostone in the area and most of these are the cliffs located near the crest of the Amabel and Manitoulin escarpments. A few other small outcrops exist on steep hill slopes where erosion has stripped the soil exposing the underlying bedrock. Solutionally sculptured boulders of dolostone can sometimes be found on hilltops where the soil mantle may be thin. Excavations at the Duntroon Marcus J. Buck Karst Solutions Page 18

27 quarry demonstrate that the glacial deposits are often quite thin at these locations. Pluhar and Ford (1970) described typical karren found elsewhere on the Niagara Escarpment. Dolines are closed karst depressions that are a diagnostic landform of karst. They are more often called sinkholes in North American literature. All of the dolines in the area would be classified as suffosion dolines, as described by Ford and Williams (1989, p. 412). Suffosion dolines are the depressions formed in the unconsolidated glacial sediment that occurs overlies the dolostone bedrock in the region. They do not require the development of depressions in the underlying bedrock. However, infiltrating water must be directed to solution channels within the bedrock that act as drains. Infiltrating water washes soil into the drains. Thus, the drains must be interconnected to highly efficient pathways for sediment transport that ultimately transport the sediment to springs. The surface depressions can form either by gradual subsidence of the soil cover (Photos 1 and 2), or by sudden collapse after soil piping creates a cavity in the soil above the bedrock drain (Photo 3). White (1988, p. 27) described such dolines as cover subsidence or cover collapse sinkholes, depending on the mechanism of formation and there are examples of both in the area. The distinction made between small and large dolines in this study is arbitrary. Since most of the dolines are small, this distinction serves to highlight the location of larger dolines on the maps, a few of which are substantial in size. Although suffosion dolines are common in the area, there are also larger closed depressions found on the thick glacial deposits that occur in the area as broad, hummocky hills and ridges. These depressions are as much as 6 m deep and may be over 30 m across, and one example contained a seasonal pond. These are glacial kettles and good examples can be found towards the west end of 26/27 Sideroad and to the south of Singhampton Cave. In contrast, the suffosion dolines are smaller and tend to be located along the base of valleys or where the overburden is thin. There are a number of sinking streams in the area. In some examples, the surface watercourses terminate abruptly at dolines where all of the surface flow is captured into the underlying karst aquifer (e.g., Camarthen Wetland Tributary sinks at SW26). These provide a clear indication of karst development. However, the majority of the sinking streams do not sink at dolines but lose flow by infiltration through the glacial sediment (Photos 4 to 6). There are examples where all of Marcus J. Buck Karst Solutions Page 19

28 the infiltration occurs at discrete locations. However, flow is more often lost gradually along a losing reach that may extend for tens to hundreds of metres. For these streams, the relationship to karst is subtle and cannot be demonstrated unequivocally without groundwater tracing. Springs are quite numerous along the Amabel and Manitoulin escarpments but can also be found on the Amabel plateau. There are also artificial examples within the existing quarry (Photos 22, 23, 24). The majority of the springs occur as discrete concentrations of groundwater discharging from the Amabel and Manitoulin aquifers. Although very few were observed issuing directly from bedrock, those that do clearly emerge from solutionally widened conduits (Photos 11 and 13). Most of the springs issue from the base of talus slopes or from thin overburden overlying the bedrock (Photos 10, 12, 14, 17). In the latter case, the springs occasionally issue from soil pipes (Photo 9). However, the local geology dictates that most of these likely originate as springs issuing from the dolostone aquifers. The localized concentrations of flow suggest that the springs are discharging from karst conduits, to which groundwater flow is focussed from small to mid-sized springsheds. The springs are not evenly distributed, and in many cases they are clustered together in close proximity. This is common in karst. Groundwater flow may be focused toward embayments along the Niagara Escarpment because of steeper hydraulic gradients towards these areas. However, in many cases the clustering of springs signifies the tendency for divergent flow to distributary springs. Some of the closely spaced springs that appear to be interrelated are referred to here as spring groups. Within the spring groups, individual springs may act as underflow or overflow springs, depending on their elevations and the geometry of the conduit networks that feed them. Only three of the springs inventoried are unlikely to be associated with the Amabel or Manitoulin aquifers. One of these at Site 11 likely discharges from the glacial sediment since it occurs at the edge of a prominent ridge with kettles. The other two springs are located at Sites 204 and 205 and these occur well below the elevation of the Manitoulin Formation. These are both small springs and their origin is unknown, although they may be discharging from an overburden aquifer. Marcus J. Buck Karst Solutions Page 20

29 Discharge measurements were conducted at most springs during high flow in spring and low flow in summer or fall such that the typical range of discharge at each spring is known. Table 2 lists the number of springs identified for each aquifer for which there are sufficient data for their size classification using the scheme of Meinzer (1923, p. 53). Using his metric classification, springs are classified according to their median discharge into one of eight magnitudes, with magnitude 1 being the largest (median discharge greater than 10 m 3 /s), and magnitude 8 being the smallest (median discharge less than 10 cm 3 /s). Table 2. Number and size of springs and spring groups that occur in each aquifer. Aquifer Amabel Manitoulin Spring Magnitude * Overburden 6 Unknown 5 6 Mean Discharge (L/s) Frequency (by range) Frequency (by magnitude) * Spring magnitude based on the metric system classification of Meinzer (1923, p. 53) using mean discharge. Marcus J. Buck Karst Solutions Page 21

30 None of the springs in the study area is larger than magnitude 4. However, there are a number of mid-sized springs with peak discharges ranging up to about 60 L/s. The size distribution of Amabel and Manitoulin springs is illustrated in Figure 2 in half-magnitude intervals. A few of the springs were grouped, in part because of better availability of data for these spring groups, but also because those springs are interrelated. The Amabel and Manitoulin aquifers have 19 and 17 springs of magnitude 5, respectively. The spring group at Site 161 is classified as magnitude 4 but this may be overestimated because it is based on the average of only two measurements, during the spring and fall. Similarly, the majority of other springs are classified using an average of only two measurements during high and low flow conditions. As such, the magnitude of some of the springs is overestimated. Nevertheless, good data are available for most of the key springs and the overall classification is representative. The discharge measurements made during high and low flow conditions also give an indication of the variability of discharge at the springs, and the nature of groundwater recharge for the springs. Those with highly variable discharge, especially those that dry up during summer, are more likely fed by sinking stream recharge (i.e., concentrated recharge from sinking streams), whereas those with less variable discharge that continue flowing throughout the summer have a greater component of percolation recharge (i.e., widespread, diffuse recharge infiltrating either directly into bedrock or through the soil where the karst is mantled). Although the majority of springs are interpreted to be karstic, there are four possible exceptions. Three of these are at Sites 11, 204 and 205, all of which may be discharging from overburden aquifers. There is also an area about 20 m wide that extends about 200 m along the base of the Manitoulin escarpment at Site 75 where the ground is saturated much of the year. This appears to be fed by widespread seepage from the Manitoulin escarpment. This is uncharacteristic, since at most sites the discharge is focused at discrete springs. In addition to karst features, a few incidental observations were made of dug wells, cisterns, artificial ponds and abandoned pipes all located at springs that indicate current and former utilization of springs (Photos 10, 18, 19). Table 3 lists the number of springs observed where there is some evidence for use. The majority are dug wells and cisterns. Seven of these are located along the Amabel escarpment and the remaining four along the Manitoulin escarpment. Marcus J. Buck Karst Solutions Page 22

31 These were not investigated to determine whether or not they are still utilized, although most appeared to be functional. In addition, three sites were identified at or just downstream from springs where depressions were dug, and earth dams constructed from the excavated soil, to retain water in a pond. None of these are still utilized and their intended uses are unknown. Finally, steel or plastic pipes were observed at or downstream from three springs suggesting some attempt to utilize them as water supplies. However, these are no longer in use and their former uses are unknown. Table 3. Observed utilizations of springs. Aquifer Evidence for use Number Amabel, Fossil Hill (dolostone) Dug well or cistern 7 Artificial pond with an earth dam constructed from excavated soil Steel or plastic pipe found near spring 3 Manitoulin (dolostone) Dug well or cistern 4 2 Overburden (glacial sediment) Artificial pond with an earth dam constructed from excavated soil 1 At least four of the springs are currently utilized as water supplies for residents or for agriculture. These all occur where potable groundwater may be difficult to obtain otherwise. Although springs are not widely used today in the vicinity, they probably played a more significant role in the past when these areas were more extensively farmed. The opportunistic use of perennial springs would have provided a low cost source of potable water. 4.2 Karst Development on the Amabel Plateau The Amabel plateau is principally a glaciated landscape where karst landforms are neither abundant nor obvious. The plateau is mantled with a blanket of glacial sediment. Data suggest that this sediment varies from less than a metre up to nearly 10 metres in thickness. The paucity of obvious karst landforms can be attributed to the glacial sediment mantle. Karren are limited to the few areas where bedrock is exposed. Other karst landforms most likely occur where the soil mantle is thin, probably less than two or three metres thick. Suffosion dolines are common Marcus J. Buck Karst Solutions Page 23

32 within 50 m of the prominent cliff located to the north of County Road 91 along the Niagara Escarpment. There, the overburden is thin and stress-release has opened up fractures to permit rapid development of karst. However, only 19 dolines were identified elsewhere on the Amabel plateau. Additional evidence for karst development comes from the area s hydrology. A total of 73 springs emerge from either the Amabel or Fossil Hill Formations along the Amabel escarpment. Their presence indicates that a karst aquifer is developed. The groundwater for these springs is recharged from the adjacent Amabel plateau. Within a 700 to 1400 metre-wide band on the plateau adjacent to the escarpment, there is either an absence of surface streams or the surface streams sink. A series of drainage basins with internal drainage are delineated within this band, as illustrated in Figure 1. Their characteristics and surface area are summarized in Table 4. When interpreted together with the spring data, they are indicative of an underlying karst aquifer. Table 4. Karst basins identified on the Amabel plateau. Karst Basin Surface Area (ha) Holokarst Type Fluvokarst Key Features A 66 North end: a dry valley with dolines; a relict fluvial gully descending the Amabel escarpment is the former surface drainage outlet. South end: a pond located at the center has no surface outlet. B 55 SW28 watercourse sinks at an ephemeral pond at Site 7. C 68 SW9 watercourse gradually sinks downstream from Site 13B. D 23 No surface watercourses or karst features. E 25 An ephemeral stream originating from the overflow spring at SW2B sinks at large dolines. The discharge from this basin occurs at two large springs, SW2B and SW2A. F 119 The Camarthen Wetland is drained by an intermittent watercourse that sinks at the SW26 doline. The six karst basins were defined based on surface topography. Although any watercourses within the basins were investigated in the field, the perimeters were delineated from topographic Marcus J. Buck Karst Solutions Page 24

33 contours on 1:10,000-scale Ontario Base Maps. As is typical of karst, the springsheds or subsurface catchments for the numerous Amabel springs may not always correspond to the surface catchments defined by topography. The springsheds can only be determined accurately through subsurface or tracing data. A description of each karst basin follows. Basin A is 66 ha in area and occupies a large portion of the tablelands within Nottawasaga Lookout Provincial Park. A broad, shallow valley extends across this drainage basin along the northeast edge. This valley continues into Basin B, although the two basins are separated by a slight rise along the valley. There are no active watercourses in Basin A, although there is a shallow pond within the valley that is probably seasonal. A ditch has been excavated that extends from this pond to about 100 m to the south where it ends (Photo 15). The ditch may have been excavated to drain the pond. There is no other surface outlet for this pond. Farther northwest, there is a series of small to large suffosion dolines that occur along the base of the valley. Their presence and the lack of any surface channels indicate that this is a karst dry valley. A relict fluvial gully extends from just west of the doline at Site 1 to the Niagara Escarpment slope. It is initially quite shallow but increasingly becomes incised as it approaches the Amabel escarpment where it is 35 m wide and 4.5 m deep (Photo 16). It continues down the escarpment slope to an elevation of about 460 m a.s.l. where it ends rather abruptly. This suggests that the stream that once eroded this gully may have entered a proglacial lake at that elevation. If so, then the development of subsurface drainage must have occurred quite early while this lake was still present. Analysis of discharge from springs along the Niagara Escarpment suggests that groundwater flow in this basin is likely towards the northwest to a series of springs at Sites 25, 26, 27, 29, 30 and 31. Although there are numerous springs located farther to the east, their combined discharge is insufficient to account for all of the groundwater recharge from this basin. Basin B is 55 ha in area. Surface runoff collects in the centre of the basin during spring runoff to form an area with a mosaic of numerous shallow pools, and flow is from pool to pool without any defined channel. This seasonally flooded area has a surface area of about 2 ha and is drained by the SW28 watercourse, a stream that normally sinks into the overburden beneath an ephemeral pond at Site 7. Groundwater tracing indicates that the sinking stream resurges at a series of springs at SW27, located 300 m to the east. During high flow, the stream overflows the Marcus J. Buck Karst Solutions Page 25

34 pond and continues flowing on the surface towards the Amabel escarpment to the east. Groundwater tracing was conducted there and the results are reported in Section 7. Basin C is 68 ha in area. A series of shallow ponds and unevaluated wetlands (Stantec Consulting, 2005) occupy the base of a broad, shallow valley extending across the catchment. These are drained by the SW9 watercourse, an intermittent stream that gradually sinks into the overburden downstream from Site 13B. During high flow, the watercourse extends at least 250 m beyond Site 14D. It was not observed flowing any farther than this during this study. Groundwater tracing indicates that the stream resurges primarily at the SW11 spring group. A detailed investigation was conducted and the results are reported in Section 6. Basin D is a closed depression with a surface area of 23 ha that is located almost entirely within the expansion lands. There are no surface watercourses, although shallow pools form at the lowest points during spring thaw. The base of the depression is entirely mantled in glacial deposits and no dolines were found. Since this area is cultivated, it is possible that any suffosion dolines may have been deliberately filled, and small dolines may have been eradicated by tilling. Observations elsewhere in Ontario indicate that refuse and fieldstones are commonly dumped into suffosion dolines on agricultural lands, and small dolines are often buried as a result of tilling. Any surface runoff must infiltrate into the overburden. The direction of groundwater flow from this basin is not known. However, it likely contributes some groundwater to each of the surrounding catchments. Basin E is 25 ha in area. It is located at the southwest corner of the expansion lands but also extends across Grey County Road 31 onto the Highland Quarry property. An ephemeral watercourse extends from the overflow spring at SW2B to the perennial spring at SW2A. The watercourse continues from there southward to the swamp on the south side of Simcoe Road 91. This swamp is Unit 6 of the Rob Roy Swamp PSW (Stantec Consulting, 2005). Some of the flow in the watercourse sinks at two large dolines located just downstream from the SW2B spring. Water infiltrating within Karst Basin E is interpreted to discharge from the SW2B and SW2A springs. Their combined discharges are measured weekly at SW2 by Jagger Hims Limited. A detailed investigation was carried out and the results are reported in Section 8. Marcus J. Buck Karst Solutions Page 26

35 Basin F is 119 ha in area. An unevaluated wetland, the Camarthen Wetland (Stantec Consulting, 2005) occupies the centre of this basin. It has a surface area of about 30 ha and is drained by the Camarthen Wetland Tributary at its south end. This intermittent watercourse flows about 200 m to the southeast where it sinks into the large doline at SW26. This doline has not been observed overflowing. The sinking stream and its subsurface continuation are considered further in Section The six drainage basins can be categorized as either holokarst or fluviokarst, depending on the presence or absence of any surface streams. Cowell and Ford (1983) used this classification for the Bruce Peninsula, Ontario, to characterize karst development there. The northern portion of Basin A and all of Basin D are holokarstic and do not contain any active surface watercourses. The surface runoff infiltrates into the overburden or into the dolines where it recharges the underlying Amabel aquifer. The southern portion of Basin A and Basins B, C, E and F contain ponds, wetlands or surface watercourses that either sink abruptly at a doline (Basin F) or infiltrate through the overburden to recharge the Amabel aquifer. Detailed investigations conducted at several of these sites confirm rapid flow velocities to springs that are diagnostic of karst aquifers. The karst basins closest to the Amabel escarpment likely contribute recharge that is directed to the escarpment springs. The intervening area lying between these basins and the Amabel escarpment is holokarstic. Within this area, surface watercourses are absent, as are springs discharging from the mantle of glacial sediment overlying the Amabel. The western portion of Basin D and all of Basin E likely provide recharge for the two springs at SW2B and SW2A. These form the headwater of a watercourse that flows westward towards the Beaver River. To the west of the six karst basins, there are frequent ponds, wetlands and surface watercourses that occupy the low-lying areas. These flow westward towards the Beaver River or southward towards the Mad River. Although this area was not widely investigated, investigations at two sites indicate that karst has developed within this area as well. Groundwater tracing and other observations near the SW2A and SW2B springs demonstrate that a karst aquifer is well developed in Basin E, which is within the Beaver River subcatchment. Edward Lake is drained by a watercourse flowing southward and is within the Mad River Subcatchment. A few observations along this watercourse indicate that it is discontinuous. About 54 L/s were Marcus J. Buck Karst Solutions Page 27

36 observed sinking into the overburden at Site 173 on April 14, 2005 (Photo 4). The stream likely resurges farther downstream at the spring at Site 174, about 150 m farther south. A month later, the flow was about 32 L/s farther upstream at SW25 but the watercourse was dry farther downstream at Site 172. At that time, the spring at Site 174 was discharging about 14 L/s, and beyond this the stream gradually sank into the overburden and the watercourse was dry beyond Site 175. The subsurface flow from this watercourse may flow towards the Mad River gorge or it may simply resurge farther downstream along the same watercourse. These two sites are good examples of sinking stream development that can be expected throughout the area where the overburden is sufficiently thin and permeable Observations at the Camarthen Wetland Tributary and Nearby Springs The largest sinking stream on the Amabel plateau within the study area sinks at the large doline at SW26. This doline is located 1.35 km south of the existing quarry (Figure 1). Stantec Consulting (2005) referred to this watercourse as the Camarthen Wetland Tributary. Jagger Hims Limited has conducted monthly flow measurements in the watercourse since November 2003 at two sites: 1) just upstream from the doline, and about 40 m farther upstream at SW26A. SW26A is located a short distance downstream from where the stream crosses beneath a trail through twin steel culverts and is a better site for measuring flow more accurately. For the past three years, peak spring flows at SW26A have ranged from about 60 to 100 L/s (Jagger Hims Limited, 2007b). From the doline, the watercourse can be followed upstream for 200 m into the south end of a swamp. At that point, the watercourse is fed by overland flow from numerous small, shallow pools in an area forested by mixed coniferous and deciduous trees. This swamp was identified by Stantec Consulting (2005) as an unevaluated wetland, the Camarthen Wetland. It extends 1.1 km to the north to within 150 m of the existing quarry. The surface catchment for the wetland and the watercourse is 119 ha (Karst Basin F), based on topography. There is no indication that there is any significant loss of flow along the Camarthen Wetland Tributary until it reaches the SW26 doline where all the flow is lost. The stream enters the doline and sinks through clastic fill and leaf litter at the base. The doline is roughly 22 m in diameter and 4.0 m deep. Bedrock is not exposed and the doline is formed within the mantle of glacial deposits. The watercourse just upstream from the doline has incised into the glacial Marcus J. Buck Karst Solutions Page 28

37 deposits to a depth of about 2.2 m and the channel bed is coarse gravel and cobbles with no fines, thus indicating rapid velocities during peak flow. The coarse material in the channel is likely residual from erosion of the glacial sediment and is probably not transported from farther upstream. There is no indication of any surface overflow channel extending beyond the doline and Jagger Hims Limited has not observed the doline flooding at any point since monitoring began in The doline appears to be located within a broad, shallow depression. Prior to the development of this sinkpoint, there may have been a large pond within this depression. About 100 m to the southeast of the SW26 doline, there are several small suffosion dolines in a small woodlot (Sites 167, 168 and 169). These are located more or less along the base of a broad shallow valley. The largest of the dolines is 10 m long, 5 m wide and 1.4 m deep. Their origin is unclear, but they may be relict sinkpoints for a large pond that may have existed prior to the formation of the SW26 doline. There are three other closed depressions located to the north of the SW26 doline that are interpreted to be suffosion dolines. The first is located 150 m north of the SW26 doline at Site 164. It is located close to the head of a shallow fluvial gully incised into the glacial deposits. This gully can be traced using contours on the Ontario Base Map all the way to the Amabel escarpment. However, only the first and last 100 m of its path can be readily discerned in the field where steeper slopes have led to more pronounced stream incision. The two other depressions are located 70 m farther down this gully at Sites 165 and 166. The largest is 7 m long, 6 m wide and 1.0 m deep. None of the three depressions appear to be active and there is no channel along the base of the gully to indicate recent flows. The depressions may have been sinkpoints for the Camarthen Wetland Tributary prior to the formation of the SW26 doline. Alternatively, they may be relict springs, but this seems less likely. No other karst features were found in the immediate vicinity of the SW26 doline. There are numerous springs located along the Amabel escarpment to the east of SW26. The closest is a group of springs located between Sites 152 and 159. The streams discharging from these springs converge into a single watercourse at Site 161, so these springs are referred to as the 161 spring group. The escarpment was not investigated on the south side of 21/22 Sideroad. However, flow was measured crossing the road from the south at Sites 162 and 163. The first is Marcus J. Buck Karst Solutions Page 29

38 a small watercourse at the base of the escarpment slope and the second drains a wetland feature located next to 21/21 Sideroad, and both may be spring-fed. Farther to the north, there are springs at Sites 149, 147, 146 and at SW22. There is minimal discharge from the intermittent spring at Site 146 so this water may be derived from the adjacent escarpment slope. However, all of the other springs discharging from the escarpment slope are likely discharging from the Amabel aquifer. Most of them are at the elevation of the Amabel or Fossil Hill Formations and the spring at Site 159 issues from talus only a few metres below an outcrop of Amabel dolostone. Table 5 lists the measurements of discharge, electrical conductivity and temperature in the Camarthen Wetland Tributary and at the various springs during moderately high and low flow conditions in The Camarthen Wetland Tributary provides an obvious source of sinking stream recharge to the Amabel aquifer. The electrical conductivities measured there were significantly lower than at any other site in the study area. It had values of 195 µs/cm in May and 270 µs/cm in November. There was a wide variation in the electrical conductivities measured at the springs, especially in May. However, only the central springs within the 161 spring group had low values suggesting recharge from the Camarthen Wetland Tributary. The values measured at Sites 152s, 153, 154, 156 and 157 ranged from 266 to 274 µs/cm on May 15. These values were lower than at any other springs within the study area. The adjacent springs at Sites 159 and 152n had somewhat higher values but not as high as the other sites located farther to the north and south. The anomalous values of electrical conductivity at the 161 spring group are an indication that these springs may be the resurgences for the Camarthen Wetland Tributary. Assuming this to be correct, the contribution of sinking stream recharge to the 161 spring group can be calculated from the discharge measurements. During May, sinking stream recharge would have contributed roughly 53% of the total recharge. The remaining recharge would have had an electrical conductivity of about 381µS/cm, much closer to the values observed at most of the other springs. During November, sinking stream recharge would have contributed roughly 16% of the total recharge. The remaining recharge would have had an electrical conductivity of about 511 µs/cm, a value more typical of the majority of springs. Presumably, the remaining recharge is derived from percolation recharge, or widespread infiltration of precipitation through the glacial deposits that overlie the Amabel aquifer. During peak flow, the relative contribution of sinking stream recharge to the 161 spring group should be at its highest and its relative contribution should diminish as flows in the sinking stream decrease. Marcus J. Buck Karst Solutions Page 30

39 Table 5. Surface water monitoring data for SW26 and the nearby springs on May 15 and November 17, May 15, 2005 November 17, 2005 Site Q EC Temp Q EC Temp (L/s) (µs/cm) ( C) (L/s) (µs/cm) ( C) SW SW , , n s , Measurements were made immediately downstream from the springs on May 15, but were better measured farther downstream at alternate sites on November Data for Site 161 are calculated from measurements at Sites 152, 155, 158 and 160. The data for Site 161 represent the combined discharge from the spring group. 4.3 Karst Development on the Manitoulin Bench The Manitoulin bench is nearly continuous along the Niagara Escarpment within the study area. The distribution of karst features along the Manitoulin bench and the adjacent escarpment indicates that karst is developed where the mantle of glacial sediment is thin and sufficiently permeable. A total of eight suffosion dolines, 27 sinking streams and 59 springs were observed. Of these, the vast majority occur where the Manitoulin bench is planar and has a gentle slope, Marcus J. Buck Karst Solutions Page 31

40 regardless of the width of the bench. These are the areas where overburden is probably two or three metres thick at most and any surface runoff is able to infiltrate through the soil mantle. Of the 6.6 km investigated along the Niagara Escarpment between the Grey-Simcoe County line and 21/22 Sideroad, there are only two short intervals where the Manitoulin bench appears to be absent. The first is north of County Road 91 where there is a large cliff formed in the Amabel dolostone. The prominent talus slope beneath this cliff is continuous without any break at the elevation of the Manitoulin. However, there may be a narrow erosional bench buried beneath the talus. The second location is on the north side of 26/27 Sideroad where there is a prominent embayment in the Niagara Escarpment and where the glacial deposits may be thicker. Elsewhere, the nature of the bench varies considerably. It ranges from about 10 to 500 m in width. In places it forms a planar surface with a very gentle slope where the mantle of glacial sediment is thin, but elsewhere the surface is marked by more rolling topography and deeply incised gullies indicative of thicker glacial deposits. Two moraines lie on the bench, both characterized by gentle rounded crests at an elevation of about 455 to 460 m a.s.l. The first extends from County Road 91 almost to 26/27 Sideroad. The second extends from 0.5 to 1.1 km north of 26/27 Sideroad. Their subtle expression and gentle contours may reflect lacustrine reworking. Clearly, there is considerable variation in the form and thickness of glacial sediments that overly the Manitoulin bench. Two areas were observed along the Manitoulin bench where the overburden is thin and surface water is able to infiltrate into the Manitoulin aquifer. The first stretches from Site 113 in the north to Site 112 in the south (Figure 1). Water discharging from the Amabel aquifer issues from a series of 14 small springs located along the base of the talus slope at the west edge of the bench. Each spring is at the head of a small watercourse. Some of these watercourses sink almost immediately upon reaching the Manitoulin bench, either at suffosion dolines or by infiltration into the overburden. The larger watercourses extend farther out across the bench but these, too, gradually infiltrate and none of the streams were observed extending completely across the bench. These sinking streams are expected to resurge at the numerous springs located along the Manitoulin escarpment. Two groundwater traces were conducted here and these confirm that the sinking streams resurge at springs located along the Manitoulin escarpment. The results of the groundwater traces are reported in Sections 5.0 and 6.4. Marcus J. Buck Karst Solutions Page 32

41 The second area is much larger and is located north of 26/27 Sideroad. It extends from west of Site 49 in the north to Site 74 in the south (Figure 1), a distance of nearly two kilometres. Here, the Manitoulin bench ranges from 200 to 500 m in width, has a slope of less than 5 m per 100 m, and forms a distinct planar surface. Once again, water discharging from the Amabel aquifer issues from a series of 11 small springs located along the base of the talus slope at the southwest edge of the bench. Each spring is at the head of a small watercourse that descends to the elevation of the bench then gradually infiltrates into the overburden. Most of the streams sink completely within 50 m, although a few extend somewhat farther. No suffosion dolines were observed. Along the Manitoulin escarpment, there are a total of 22 small springs. Most of these emerge just below the crest of the escarpment. Dolostone often outcrops at the crest and the springs are typically located within a few metres down the slope. A few of the springs issue from overburden farther down the escarpment slope but these, too, likely discharge from the Manitoulin aquifer. The lack of suffosion dolines may reflect the properties of the soil or the immaturity of the karst. The measured discharges from the springs support the interpretation that the Manitoulin springs are fed in part by the sinking streams on this segment of the Manitoulin bench. Table 6 indicates the total discharge from both the Amabel and Manitoulin springs during high flow in spring and low flow in fall. The widely distributed but small springs issuing from the Amabel here suggest that each spring has a small catchment fed by the adjacent holokarst on the Amabel plateau. The total discharge from the Manitoulin springs is approximately double that of the Amabel springs, regardless of season. This is consistent with the Manitoulin springs having twice the effective catchment area as a result of capturing the flow from the Amabel springs. No groundwater tracing was conducted in this area. Table 6. Total discharge (L/s) measured from selected Amabel and Manitoulin springs during high and low flow conditions. Aquifer Selected Springs May 9-13, 2005 Nov , 2005 Amabel (34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44) Manitoulin (49, 50, 51, 52, 54, 55, 56, 57, 58, 59, 60, 61, 62, 64, 65, 67, 68, 70, 71, 72, 73, 74) Marcus J. Buck Karst Solutions Page 33

42 In contrast to the previous two areas, the southern segment of the Manitoulin bench extending from County Road 91 to 21/22 Sideroad has little evidence of karst development. One small suffosion doline was noted at Site 134 in 2005, although later that year it was filled in when the fields were tilled. There are also two small watercourses that gradually sink into the overburden that are fed by springs at Sites 133 and 136. However, no springs were detected anywhere along the Manitoulin escarpment. The glacial deposits in this area appear to be thicker and the two largest watercourses crossing the bench have incised deeply into the overburden without intersecting bedrock. This indicates that the thicker mantle of glacial deposits has limited infiltration and inhibited karst development. The one remaining segment of the Manitoulin bench extends for 700 m south of 26/27 Sideroad. The bench here is quite narrow and has a greater slope than elsewhere. Although the Manitoulin dolostone often outcrops along the crest of the Manitoulin escarpment here, it appears that the mantle of glacial sediment on the bench is thicker. Despite this, there are two streams that gradually infiltrate into the overburden. The first originates at a small perennial spring issuing from the Amabel aquifer at Site 77. The stream sinks eventually after flowing as much as 200 m, despite peak flows of less than 2 L/s. A second stream originates at a large perennial spring issuing from the Amabel aquifer at Site 86. This stream does not sink until it approaches within 20 m of the Manitoulin escarpment where the overburden is thin, just downstream from SW21C. The series of springs at Sites 84 and 85 are the likely resurgences. Although the glacial sediment cover on the Manitoulin bench is thicker at this segment, the presence of several springs at the elevation of the Manitoulin escarpment indicates that surface water is able to infiltrate into the Manitoulin aquifer, at least close to the escarpment, and that karst has likely developed here. 4.4 Measurements of Streamflow around the Study Area Perimeter Streamflow was measured at all watercourses that potentially originate in or adjacent to the detailed study area. These measurements were made along public roads and were taken during low flow conditions on October 26, 2004 and again during moderate flow conditions on May 16 to 17, The data are listed in Table D-1 in Appendix D. Figure 1 illustrates the monitoring locations as well as the recorded flows. Marcus J. Buck Karst Solutions Page 34

43 The data are consistent with the discharges measured farther upstream at the numerous springs that occur at the head of these creeks. A number of the streams located along 31/32 Sideroad and Pretty River Road likely originate at a series of karst springs located along the Manitoulin and Amabel escarpments within Grey County and represent discharge from the Amabel and Manitoulin aquifers. The watercourses located farther south along Pretty River Road as well as along Grey Sideroad 30 may be fed in part by discharge from the Amabel aquifer. Alternatively, there could be significant discharge from glacial deposits. Regardless, there is no indication that there may be any karst springs there that are significantly larger than those observed within the detailed study area. 5.0 Investigation at the Manitoulin Bench An investigation was conducted at the Manitoulin bench to characterize the karst, to compare aquifer recharge and discharge, and to determine groundwater flow velocities in the Manitoulin aquifer. In addition to field mapping and measurements of spring discharge, a preliminary groundwater trace was conducted here in anticipation of more complex tracing from the SW9 watercourse. 5.1 Site Description Field mapping of karst features and springs was conducted at the Manitoulin escarpment to the north of Simcoe County Road 91. The results are illustrated in Figure 3. At this site, there is a prominent erosional bench formed on top of the Manitoulin Formation that clearly separates the Amabel and Manitoulin escarpments. Bedrock is often exposed near the crest of the Amabel escarpment and there is some talus intermixed with glacial deposits extending to the base of the slope. The Manitoulin bench slopes gently to the northeast and is covered with a continuous blanket of glacial deposits. Most of the bench is currently tilled where it is sufficiently wide. The transition from the Manitoulin bench to the Manitoulin escarpment is abrupt and the escarpment has a relatively steep slope. The thin-bedded dolostone that often outcrops near its crest is the resistant cap rock that must underlie the distinct erosional bench. The Manitoulin bench narrows to the north and eventually disappears. At this point, the crest of the Amabel escarpment is marked by prominent cliffs ranging from 10 to 20 m in height. The extensive talus Marcus J. Buck Karst Solutions Page 35

44 apron beneath this extends to well below the Manitoulin Formation and the erosional bench is absent or buried beneath Amabel talus. One other prominent landform occurs at the site, a ridge of glacial sediment situated 50 m northeast of and parallel to the Manitoulin escarpment. This low, gentle ridge is tentatively interpreted to be a moraine. Its gentle contours suggest lacustrine reworking from a proglacial lake. A number of small springs were located at the base of the Amabel escarpment along the edge of the Manitoulin bench. There are also a few suffosion dolines located close to the springs, and some of the flow from the springs is obviously captured at these features. When flows are sufficiently high, the discharge from the larger springs flows out across the bench for some distance before gradually sinking into the soil. Although two of these streams extended to within a few metres of the Manitoulin escarpment during peak spring runoff, they were never observed flowing over the escarpment. The quantity of water discharging from the springs indicates that most of the water must be discharging from the Amabel aquifer farther up the slope. Similarly, there is a series of small springs located all along the base of the talus slope beneath the Manitoulin escarpment. At Sites 101 and 102, there are poorly defined channels extending up the talus slope to discrete springs near the crest, located just below outcrops of dolostone. However, similar channels were not observed at the majority of the springs, and the streams generally flow beneath the talus to emerge at the base of the talus slope. Like the Amabel springs above, the quantity of water discharging from these springs indicates that most of the water must be discharging from the Manitoulin aquifer farther up the slope, with the exception of the few springs located to the northwest where the Manitoulin bench is absent or buried. These closely spaced springs, referred to as the SW11 spring group, have a combined discharge that ranges up to 70 L/s at peak flow. Most of their discharge may issue directly from the Amabel aquifer 80 m farther up the slope. The discharge from the Manitoulin springs collects in the two watercourses that feed into an artificial pond, referred to here as Franks Pond. The two watercourses, one flowing from the northwest (SW11 watercourse) and the other from the southeast (SW12 watercourse), occupy the base of the valley that lies between the escarpment and the adjacent moraine. The SW11 Marcus J. Buck Karst Solutions Page 36

45 watercourse is fed by groundwater discharge from the Manitoulin and Amabel aquifers. The SW12 watercourse extends for 450 m to just north of Simcoe Road 91. Like the other watercourse, there are springs located along much of its length, although these are more widely dispersed. Much of its flow is from groundwater discharging from the Manitoulin aquifer. Franks Pond occupies a notch cut into the moraine from the combined flow of these two tributaries. Between the tributaries, there are a few additional springs located at the base of the talus slope at Sites 93, 94, 95, 96, 97, 98 and 101 that provide some flow directly into the pond. 5.2 Results of the Groundwater Trace from Site 114 A groundwater trace was conducted on April 19, A small amount of uranine (3.25 g) was injected into a small sinking stream perched on the Manitoulin bench. The dye was injected into the stream just downstream from the Amabel spring at Site 114 (Figure 3). At the time, the stream was observed gradually sinking into the overburden over a distance of about 22 m. Water samples were collected periodically at the nearby springs below the escarpment until measured fluorescence approached background values at key monitoring sites. A total of 19 sites were monitored extending from the SW12 watercourse at Site 105 in the east to springs at Site 227 in the north. The three springs located near the top of the escarpment slope at Site 99, 100 and 100A were only sampled once. Sufficient samples were taken at most locations to adequately define breakthrough curves for the trace. The measured background fluorescence ranged from 0.2 to 0.6, expressed as µg/l of uranine, which is equivalent to parts per billion (ppb). The tracer was detected at eight sites and the peak concentrations of the tracer after subtracting background fluorescence are indicated in Table 7. The tracer concentrations at Sites 96, 97, 98, 101 and 102 are shown in Figure 4. Tracer arrival first occurred at Site 102, a convenient monitoring point at the base of the escarpment slope along a watercourse extending down from the springs at Sites 99 and 100. The peak tracer concentration measured at Site 102 was 5.9 µg/l, and this occurred 47 minutes after injection. Two springs located just to the north of Site 102 had similar breakthrough curves. Spring 98 had the highest peak concentration (12.4 µg/l), but the peak did not occur until about 2 hours after injection. The discharge from spring 98 sinks into the overburden about 15 to 20 m to the north. Spring 97 had a peak concentration of 6.5 µg/l, and this occurred about 1.6 hours after injection. This spring is probably located downstream from the spring at 98, which would Marcus J. Buck Karst Solutions Page 37

46 explain the similar shape of the breakthrough curves and the more subdued response at Site 97. Positive traces were also observed at Sites 101 and 96. These are very small springs emerging from overburden with relatively little flow. At Site 101, the peak tracer concentration was 1.0 µg/l and this occurred about 4 hours after injection. At Site 96, there was insufficient data to identify the peak. This spring may also be downstream from the spring at Site 98. About 5 hours after injection, the tracer concentrations at Sites 99, 100 and 100A were 0.8, 1.0 and 1.0 µg/l above typical background fluorescence values measured at the other sites suggesting positive traces to these springs. The relatively low values reflect the sampling time, long after the peak would have passed. At about the same time, the measured fluorescence in the stream just downstream from the injection site had returned to near background levels (0.8 µg/l). The groundwater trace established flow direction and velocities from the sinking stream at Site 114 to a series of closely spaced springs located nearby on the escarpment slope. The groundwater velocities are consistent with rapid flow along solutionally enlarged conduits. This interpretation is supported by the presence of the suffosion dolines along the western edge of the Manitoulin bench. The loss of overburden at these dolines can only be attributed to subsurface transport of sediment along enlarged fractures or conduits with sufficient velocities to transport clay, silt and sand. Flow from the other sinking streams located nearby is expected to behave in a similar fashion, flowing rapidly along channels and conduits to join the major flow paths to the springs. Figure 5 illustrates the spatial relationships between the injection site and the springs where the dye was recovered. Once through the overburden, enlarged fractures and bedding planes in the bedrock would have directed the flow to springs near the crest of the Manitoulin escarpment (e.g., the spring at Site 99). From there, some of the flow clearly followed surface channels down the talus slope. However, some flowed through the talus and overburden to the series of springs at the base of the slope at Sites 96, 97, 98 and 101. Discharge, electrical conductivity and temperature were also monitored during the trace and the results for relevant sites are also presented in Table 7. It is apparent that the total recharge to the Manitoulin aquifer from the five sinking streams is similar to the discharge measured near the crest of the escarpment at Sites 100A, 99 and 100. Similarly, the calculated electrical conductivities and temperatures of their combined flows are also quite similar. It is not surprising that the temperatures varied slightly between the recharge and discharge since this Marcus J. Buck Karst Solutions Page 38

47 would have been influenced by air temperature. However, the measured recharge and discharge, as well as the electrical conductivities are very similar (i.e., within measurement error). Table 7. Surface water data measured at the Manitoulin escarpment on April 19, Feature Type is indicated by the following codes: GI1, small intermittent spring; GP1, small perennial spring; M, monitoring point along a surface watercourse. Peak [UR] is the peak concentration of the tracer uranine after subtracting the measured background fluorescence. Measurements of flow Q are approximate, generally ± 30%. EC and Temp are the specific conductivity and temperature of the water. Site No. Type Peak [UR] Q recharge Q discharge EC Temp (code) (µg/l) (L/s) (L/s) (µs/cm) ( C) 114 GI GI GP GI GP A GI GI GI M * GI * 98 GI GP * GI * Total recharge on Manitoulin bench (Sites 114, 115, 116, 117, 118) Total discharge near top of talus slope (Sites 100A, 99 and 100) * Flows at Sites 101 and 96 were not measured on April 19, However, measurements were made at these sites during similar flow conditions on April 18, The tracing results at Sites 102 and 98 suggest mixing of groundwater, either within the bedrock aquifer or perhaps in the talus. Although the most rapid flow was to Site 102, the peak concentration of uranine at Site 98 was twice that for Site 102. This supports the interpretation Marcus J. Buck Karst Solutions Page 39

48 that groundwater from the other sinking streams located nearby to the south was mixing with the groundwater from the sinking stream at Site 114. While much of the combined discharge flowed rapidly down the surface channel to Site 102, some water flowed down through the talus to the small spring at Site 98, and this water must have had less mixing with water from the other sinking streams. Unfortunately, it cannot be determined if the mixing took place within the bedrock aquifer or in the talus, so little can be determined about the configuration of conduits within the Manitoulin aquifer. The measured tracer velocities from the groundwater trace are within the expected range for karst. Calculations based on a model of diffuse flow through the soil mantle, conduit flow in the Manitoulin aquifer, and the measured tracer velocity to Site 102 indicate that 1) the majority of the residence time for the trace was likely in the soil mantle, and 2) the flow through the overburden was likely dispersed over a relatively large area (throughout the entire area of saturated soil surrounding the stream) and not focused at just a few discrete points along the sinking stream. The groundwater tracing conducted at the Manitoulin bench indicates that karst has developed in the Manitoulin Formation where the soil mantle is thin, supporting the interpretation of karst features mapped at this site. 6.0 Investigation of the SW9 Watercourse and its Resurgences The SW9 watercourse is one of the few surface streams located on the Amabel plateau close to the Niagara Escarpment and, like most of the other watercourses, it sinks before reaching the Escarpment. It is possible that dewatering of the proposed expansion quarry could affect this watercourse, so a detailed study was conducted to: 1) determine the nature of streamflow losses along the SW9 watercourse, 2) determine where the sinking stream resurges, 3) determine travel times to the resurgences, and 4) better define the relationship between groundwater flow in and between the Amabel and Manitoulin aquifers. In addition to a groundwater trace conducted at the SW9 watercourse, a trace was conducted simultaneously from a small sinking stream perched on the Manitoulin bench at Site SW10. Marcus J. Buck Karst Solutions Page 40

49 6.1 Site Description Figure 6 illustrates the location of the SW9 watercourse relative to key springs located along the Niagara Escarpment. Jagger Hims Limited (2007b) have monitored surface flows monthly along the creek at SW9 since May The stream generally dries up for several months of the year during summer and fall but flows reach about 40 L/s during peak spring runoff. The lower reach of the SW9 watercourse was mapped during the spring of From SW9, a small, defined channel extends 100 m upstream to where it drains an area forested in cedars that floods each spring to a depth of a few tens of centimetres. Downstream from SW9, the watercourse was traced for nearly 500 m. Along this reach, a defined channel is usually absent, and most of the watercourse can only be mapped by following the stream during peak flows. Although there are a few shallow depressions along this reach, there is no clear indication that dolines have formed. However, there are outcrops of dolostone on either side of the watercourse starting at Site 13A and extending for about 200 m downstream. These indicate that the overburden is often thin beneath the watercourse, and probably less than one or two metres thick. The slightly hummocky nature of the ground surface in this wooded area suggests that karst processes may be active along this reach. About 20 m downstream from this reach, the watercourse continues as an obvious ditch that extends for 100 m through a forested area to the edge of a grassy meadow. From here, the path of the stream was traced for an additional 150 m across the meadow by following the obvious path where the stream had melted the snow a few days prior to mapping. Bedrock does not outcrop along the final 270 m of the watercourse where the overburden may be thicker. Farther to the east, numerous suffosion dolines were observed on the Amabel plateau. Most are quite close to the Niagara Escarpment, but a few are as much as 100 m from its crest. Many of these dolines are distinctly elongated indicating the strong influence of underlying fractures in the Amabel dolostone. Although these features were not mapped, there appears to be a greater concentration of dolines where the Amabel dolostone forms a prominent cliff at the crest of the escarpment. These observations suggest that stress release from unloading along the Niagara Escarpment has opened up many of the fractures in the dolostone close to the Escarpment, and this has encouraged the rapid development of integrated channel networks leading to the formation of the suffosion dolines. Although karst processes were not likely responsible for Marcus J. Buck Karst Solutions Page 41

50 initial enlargement of the fractures, the structural unloading has permitted the rapid development of karst. Observations elsewhere indicate that suffosion dolines are uncommon farther from the escarpment. It was anticipated that the SW9 watercourse should resurge at some of the springs located along the Niagara Escarpment to the east, since the hydraulic gradients should be steepest in this direction. The stream sinks near the centre of a sizeable promontory so subsurface flow could potentially resurge anywhere around the perimeter. Although there are large springs located at the north and south of the promontory, the sinking stream was expected to resurge at the concentration of springs located almost due east at the SW11 spring group. The substantial flows observed here indicate a large catchment close by, and the sinking stream recharge from the SW9 watercourse seemed to be the likely source. 6.2 Streamflow Losses along the SW9 Watercourse The preliminary observations of the SW9 watercourse suggested that it gradually loses flow starting at Site 13A where dolostone first outcrops close to the watercourse. On April 23, 2004, the flow measured at SW9 was 6 L/s and all of this sank gradually into overburden about 40 m farther downstream in the vicinity of Site 13A. To better understand the nature of flow losses, a series of flow measurements were made along the watercourse the next year on April 25 during high flow. The results are illustrated in Figure 7. Discrete losses of flow were only observed at Sites 14C and 14D. At the first site, 6 L/s was observed diverging from the main stream and sinking into overburden within a shallow depression. Similarly, 2 L/s was observed sinking into the overburden at a shallow pool at the terminus of the stream at Site 14D. There may have been similar discrete losses of flow farther upstream, but these could not be detected because the overall streamflow was greater and small decreases in flow could not be detected. Nevertheless, it is concluded that the 39 L/s observed flowing at SW9 was gradually lost to infiltration over a distance of 220 m. The streamflow losses appear to have been dispersed over the entire distance of this reach as indicated by the overall slope of the streamflow-distance curve. However, it is more likely that there was a series of small discrete losses where the overburden cover was thin and underlain by solutionally enlarged fractures in the Amabel dolostone. Marcus J. Buck Karst Solutions Page 42

51 At the regional scale, the loss of flow along the lower reach of the SW9 watercourse represents a significant concentration of sinking stream recharge from a surface catchment area of about 68 ha. Although this sinking stream recharge may enter a conduit network draining to only a few closely spaced springs, the loss of flow over a distance of 220 m during high flow conditions increases the probability of the groundwater flowing through a larger network to more widely dispersed springs. 6.3 Results of the Groundwater Trace from the SW9 Watercourse A groundwater trace was conducted from the SW9 watercourse on April 23, A small amount of uranine (99.3 g) was injected into the stream about 23 m upstream from SW9 at Site 12. This location is about 60 m upstream from the beginning of the losing reach. The dye solution was rapidly mixed in the stream by turbulent flow in a narrow channel (Photo 7). Water samples were collected periodically at a total of 55 sites located along the Niagara Escarpment from Site 76 in the north to Site SW22 in the south (Figure 6). These sampling sites encompass all of the springs issuing from the Amabel and Manitoulin aquifers around the perimeter of the promontory where the SW9 watercourse sinks. Water samples were collected manually at most sites to provide for greater spatial resolution. An ISCO autosampler was used to collect samples more frequently at SW11E located at the downstream end of the SW11 watercourse, the largest watercourse entering Franks Pond. This stream is fed by the SW11 spring group. Sampling continued at key sites until the measured fluorescence approached background values. Sufficient samples were taken at many of the locations to adequately define breakthrough curves for the trace. The tracer was clearly detected at a total of 19 sites. In addition, abovebackground fluorescence concentrations were measured at an additional four sites but low concentrations and sampling frequency make interpretation inconclusive. The results are summarized in Table 8. Figure 6 illustrates the spatial relationships between the sinking stream and all of the springs sampled during the groundwater trace and Figure 8 shows details where the majority of the dye was recovered. Tracer concentrations at Sites SW11E and 105 are illustrated in Figure 9. Marcus J. Buck Karst Solutions Page 43

52 Table 8. test. Surface water sites where the tracer was recovered from the SW9 watercourse tracer Feature Type is indicated by the following codes: GI1, small intermittent spring; GP1, small perennial spring; GP2, large perennial spring; M, monitoring point along a surface watercourse. Peak [UR] is the peak concentration of the tracer uranine after subtracting the measured background fluorescence. Measurements of flow Q are approximate, generally ± 30%. EC is the specific conductivity and Temp is the water temperature. Site Type (code) Peak [UR] (µg/l) Q recharge (L/s) Q discharge (L/s) EC (µs/cm) Temp ( C) SW9 M SW21C M (89) GI GI SW21D M w GI SW11D GP e GI SW11B GP GP SW11A GP GI GP GI * SW11E M GI * 95 GI * 96 GI * 97 GP GI * 101 GI * 102 M M GI * 116 GI * SW12A M (134) M * GP * Allogenic recharge on Amabel plateau (The SW9 watercourse, at SW9) Discharge at the Niagara Escarpment (Sites SW11E, 94, 95, 96, 97, 101, 102) 88 * Measurements of flow, electrical conductivity and temperature were made under similar flow conditions between April 18 and 23. Marcus J. Buck Karst Solutions Page 44

53 At Site SW11E, the first arrival of the tracer occurred 3.6 hours after injection and the tracer peaked at a concentration of 12.1 µg/l 8.0 hours after injection. The majority of the dye cloud passed within the first 24 hours and the measured fluorescence returned to background levels within six days. The stream at this site is fed by spring discharge from Sites 227, SW11D, SW11C, SW11B, 228, SW11A, 91 and 92, or the SW11 spring group. The measured fluorescence at the individual springs 12 hours after injection ranged from 5 to 17 µg/l. Since these sites are upstream from SW11E, the peak would have passed about four hours earlier so these values are well below the peak tracer concentrations. Nevertheless, the dye cloud clearly passed all of these springs and at relatively high concentrations. It is concluded that the SW11 spring group is the primary resurgence for the SW9 watercourse. Dye was also recovered at several other springs. The peak tracer concentrations at Sites 114 and 116 were at least 4.6 and 6.3 µg/l, respectively (Figure 10). Clearly, some of the flow from the SW9 watercourse resurged at these Amabel springs. As discussed in Section 5, the discharge from these springs sinks on the Manitoulin bench and resurges at several nearby springs located along the Manitoulin escarpment at Sites 96, 97, 98, 99, 100, 100A, 101 and 102. Therefore, it is not surprising that the dye was also recovered at these springs, where the peak tracer concentrations ranged from 0.3 to 1.0 µg/l. Their peak concentrations were lower because the springs are located farther downstream and because of high dispersion in the intervening talus. Dye was also recovered at three other Manitoulin springs located just to the northwest at Sites 93, 94 and 95. Once again, their peak tracer concentrations were relatively low, ranging from 1.7 to 2.7 µg/l. In addition, low concentrations of the tracer also appeared to be detected at seven other sites (105, SW12A, 133, 136, 89, 90, and SW21D). However, there were too few samples and the dye concentrations were too low at all of these sites to assess dye recovery with confidence. By combining the tracing data with measurements of discharge, the mass of dye recovered at the various springs can be calculated from integration of the breakthrough curves. Since the discharge measurements are accurate to ± 30%, the calculated recoveries can be used to approximate the distribution of flow to the various springs where the tracer was recovered. Of the 99.3 g of uranine that was injected into the SW9 watercourse, about 64 g of the dye was Marcus J. Buck Karst Solutions Page 45

54 recovered at the various springs. The remaining dye would have been lost due to photodecay, microbially mediated decomposition, and to adsorption onto organic matter and sediment. The recovery of about 64% is typical of groundwater traces in karst, especially considering that the stream sinks through overburden before entering the Amabel aquifer. About 58 g of the dye were recovered at the SW11 springs, as measured at SW11E. In contrast, about 5 g of dye was recovered from all of the other springs combined. Therefore, about 90% of the flow lost along the lower reach of the SW9 watercourse resurges at the SW11 spring group. The remainder is distributed amongst the various other springs to the north (SW21C, SW21D, 90, 88) and south (Sites 133, 136, 114 and 116, and from Site 93 to Site 105). During the groundwater trace, the electrical conductivities measured at all of the individual SW11 springs were nearly identical, ranging from 340 to 348 µs/cm. These values are very similar to the electrical conductivity measured at the SW9 watercourse a few hours earlier in the day, which had a value of 361 µs/cm. The consistent values for the conductivities indicate that the groundwater was well mixed prior to issuing from the Amabel aquifer. The minor variations likely reflect the introduction of minor infiltration recharge from the talus slope. The wide distribution of the springs at the base of the talus slope may be partly due to a pattern of divergent flow through the talus as the various streams descended the escarpment slope. However, the distribution of the SW11 springs over a width of 120 m cannot be fully explained by this mechanism, indicating that there must be a pattern of distributary flow in the Amabel to several Amabel springs hidden beneath the talus near the crest of the escarpment. Furthermore, the position of the springs at Sites 91 and 92 suggests that some of the discharge from the Amabel aquifer sinks into the Manitoulin aquifer immediately upon reaching the elevation of the Manitoulin bench. This water must then flow through the Manitoulin aquifer to springs hidden beneath the talus on the Manitoulin escarpment above Sites 91 and 92. This all points to a pattern of distributary flow in the Amabel aquifer to a series of Amabel springs spaced over a distance of about 100 m. Table 8 includes a comparison of the sinking stream recharge to the Amabel aquifer at the SW9 watercourse with the discharge from the principal resurgences along the Niagara Escarpment. The springs at Sites 114 and 116 are not included in the sum of the discharge since they are upstream from some of the resurgences at the base of the Manitoulin escarpment. Roughly 34% Marcus J. Buck Karst Solutions Page 46

55 of the combined flow from the resurgences was derived from the SW9 watercourse. Similarly, only about 43% of the recharge for the SW11 spring group was from the SW9 watercourse. While there may be some streamflow losses farther up the SW9 watercourse that contribute sinking stream recharge to the Amabel aquifer, the presence of various wetlands there suggest that any additional sinking stream recharge from there is minimal. Therefore, it is concluded that although these springs obtain a significant component of sinking stream recharge (i.e., from the SW9 watercourse) they receive an even greater component from widespread percolation recharge on the Amabel plateau. This indicates that there must be significant infiltration through the soil mantle overlying the Amabel aquifer and from a large area. With respect to the proposed quarry at the expansion property, it can be concluded that even a significant loss of flow in the SW9 watercourse as a result of quarrying would not cause the SW11 springs to dry up. The paucity of surface streams elsewhere on the Amabel plateau near the escarpment implies that many of the other escarpment springs are fed primarily by percolation recharge as well and these, too, are not likely to be significantly impacted by the proposed quarrying. 6.4 Results of the Groundwater Trace from SW10 A groundwater trace was conducted from Site SW10 on the Manitoulin bench (Figure 3). A small amount of phloxine B (8.7 g) was injected into the sinking stream just downstream from the water supply system (Photo 8). At the time, the SW10 stream sank into the overburden just upstream from the doline at Site 124, within 20 m of the base of the Amabel escarpment. The nearest point along the crest of the Manitoulin escarpment is 150 m to the northeast. This trace was conducted simultaneously with the SW9 watercourse trace so the same water samples collected for that trace were also analyzed for phloxine B. The tracer concentrations measured at Sites SW11E and 105 are illustrated in Figure 11. A good breakthrough curve was obtained for SW11E. The first arrival of the tracer was 6 hours after injection and the measured fluorescence returned to background levels 34 hours later. The concentration of phloxine B reached a peak of 1.9 µg/l above background fluorescence 14 hours after injection. The characteristic shape of the breakthrough curve provides evidence that flow from the sinking stream at SW10 resurged at the SW11 springs, although the peak concentration was low. During the trace, the flow measured at SW10 was only 0.2 L/s whereas the combined discharge from the SW11 springs was 70 L/s. Therefore, the observed low peak in tracer Marcus J. Buck Karst Solutions Page 47

56 concentration at the SW11 springs was a result of substantial dilution. The few measurements at the individual SW11 springs indicate that the tracer was recovered at all of these and at similar concentrations as those measured at SW11E. However, there were too few samples to adequately define breakthrough curves for the individual springs. Nevertheless, the results of the trace established a subsurface connection to the conduit(s) feeding the SW11 springs and the observed tracer velocity is typical for flow through solutionally enlarged conduits in karst. At Site 105, background fluorescence was more variable than at SW11E (Figure 11). Two individual measurements were well above background fluorescence and suggest that the tracer was also recovered at this site. However, this interpretation is not conclusive. The peak concentrations were too low to determine if subsurface flow connections exist to any other springs. 7.0 Investigation of the SW28 Watercourse and its Resurgences The SW28 watercourse is one of the few surface streams located on the Amabel plateau close to the Niagara Escarpment and, like the SW9 watercourse, it sinks before reaching the Escarpment (Figure 1). A groundwater trace was conducted from this site to: 1) characterize the nature of groundwater recharge from the stream, 2) determine where the sinking stream resurges, 3) measure groundwater flow velocities, and 4) determine the relative importance of sinking stream and percolation recharge to regional springs. 7.1 Site Description Figure 12 illustrates the location of SW28 along a small watercourse, the surface catchment for the watercourse, and the various springs located nearby along the Niagara Escarpment. The surface catchment for the SW28 watercourse is about 55 ha, or slightly smaller than that for the SW9 watercourse. Observations were made during moderately high flow conditions and, from these, it is estimated that peak flows during spring runoff each year are likely in excess of 20 L/s. There are virtually no defined stream channels throughout the catchment. During peak runoff each spring, an area of shallow, interconnected pools forms in the center of the catchment along the base of the broad shallow valley. Part of the seasonally flooded area extends southward Marcus J. Buck Karst Solutions Page 48

57 through a reforested area towards 26/27 Sideroad. The seasonally flooded area also extends northward across open forest and meadows. Although no longer farmed, this valley was once tilled and surface channels may have been eradicated. Surface runoff collects in this low area then winds its way through the interconnected pools to a poorly defined channel that drains to the east. Runoff follows this grassy channel only a short distance before entering a shallow, ephemeral pond occupying a shallow basin at Site 7. Here, the water infiltrates into the overburden beneath the pond. The size of the pond varies as a function of the flow entering from the watercourse. Flows were occasionally measured just upstream from the pond at SW28. It is only during brief periods of peak runoff that the capacity of the sinkpoint is exceeded and the pond overflows the basin. The excess water exits the basin at the east end and continues on the surface towards the Amabel escarpment. Although the flood waters initially follow a fairly defined path, any stream channel that may have existed there once has since been eradicated by tilling. However, a distinct fluvial gully has formed where the watercourse approaches the Amabel escarpment. This is incised into the glacial deposits that overlie the Amabel dolostone. The gully gradually deepens as it approaches the escarpment and at the brow it has cut down to expose the Amabel dolostone. The SW28 watercourse and the seasonally flooded area that forms its headwaters dry up during the summer. On April 22, 2005 the stream was in flood and the flow measured just downstream from the pond was about 10 L/s at Site SW28A. At that time, the stream continued on the surface to the beginning of the gully, or about 100 m upstream from the Amabel escarpment. No discrete sinkpoints were observed and the water appeared to be gradually infiltrating into the overburden along this reach, much like the SW9 watercourse along its lower reach. Furthermore, there was no indication that the stream had extended any farther at any time that spring. Nevertheless, it is likely that the SW28 watercourse does occasionally flow over the Amabel escarpment from time to time. There are a number of springs located along the Amabel escarpment to the east of the sinking stream at SW28. The largest is a group of springs at SW27, at the head of a perennial watercourse that descends the escarpment slope. These springs are located at the south edge of the SW28 flood channel where it first descends the escarpment. Figure 13 is a map illustrating the location of the individual springs within the SW27 spring group. The adjacent Amabel Marcus J. Buck Karst Solutions Page 49

58 plateau slopes very gently towards the escarpment here and the brow of the escarpment is marked by a sharp break in slope. Bedrock crops out where the SW28 watercourse has cut through the overburden at the crest of the escarpment. A total of 10 individual springs were documented there. Of these, six are perennial, four are intermittent and one is relict. All of the discharge from the springs converges into a single channel a short distance downstream and this flows continuously down the Niagara Escarpment. The combined flow from the springs was measured occasionally at Sites 46 and 47. Jagger Hims Limited measures the flow every month farther downstream at Site SW27. Their measurements indicate that the flow ranges up to 40 L/s and that the stream only stops flowing when it occasionally freezes during winter (Jagger Hims Limited, 2007b). The next largest spring is located 150 m to the south at Site 48. It is at the head of a watercourse that is also continuous down the Niagara Escarpment. Water discharges from overburden at the head of an obvious fluvial gully where the landowner has installed a dug well to make use of the spring as a water supply. Jagger Hims Limited measures the spring discharge monthly a short distance downstream at SW20. There, the flow has ranged up to 19 L/s during spring runoff and the stream was only observed drying up during very dry weather (Jagger Hims Limited, 2007b). There are six additional springs located along the Amabel escarpment within 800 m of SW28 (Sites 41, 42, 43, 44, 45 and 77). One is located 170 m south of the SW20 spring at Site 77. This small perennial spring appears to emerge from a bedrock conduit. Discharge there ranges up to 1.5 L/s. The remaining five Amabel springs are distributed along the Amabel escarpment to the north of the SW27 springs. These are all small with flows ranging up to 2 L/s. The spring at Site 44 issues from talus a few metres below a bedrock scarp, located near the top of the escarpment. It dries up during the summer. The other springs are perennial and they all issue from talus at the base of the Amabel escarpment. All five springs form the headwaters for discontinuous watercourses that gradually lose their flow to infiltration into the overburden. The streams at Sites 45 and 77 flow the farthest where the Manitoulin bench is less distinct. The remaining four streams infiltrate within a few tens of metres where the Manitoulin bench is quite distinct. Presumably, these streams provide recharge to the underlying Manitoulin aquifer. Marcus J. Buck Karst Solutions Page 50

59 There are also a number of small springs distributed along the Manitoulin escarpment farther to the east. These springs were not investigated in any detail, but are likely fed by a combination of percolation recharge on the Manitoulin bench and sinking stream recharge from the various small sinking streams that issue from the Amabel escarpment. 7.2 Results of the Groundwater Trace at SW28 A groundwater trace was conducted from the SW28 watercourse on May 10, 2005 when all of the flow from the watercourse was sinking at the ephemeral pond. A small amount of uranine (24.75 g) was injected into the stream at Site SW28, about 10 m upstream from the pond. Water samples were collected periodically at all six of the nearby springs located below the Amabel escarpment until measured fluorescence approached background levels where the dye was detected. The springs were sampled for seven days with sufficient frequency such that any dye should have been detected if conduit connections exist. An ISCO autosampler was used to collect water samples in the SW27 watercourse at Sites 46 and 47, a short distance downstream from the spring group. In addition, most of the individual springs in the SW27 spring group were also sampled, but less frequently. Finally, two samples were collected from the ephemeral pond 50 and 85 hours after injection to measure the residual concentration of the dye. After the injection into the creek, the dye was rapidly washed into the pond. For the next few hours, the dye cloud was clearly visible as a crescent-shaped band that gradually moved across the pond as clear water from the SW28 watercourse gradually displaced it (Photo 6). About 3 hours after the injection, the band had moved roughly halfway across the pond. There was no indication from the movement of the dye cloud that there was any focused infiltration of the water through the overburden. At 11 hours after the injection, the dye was barely visible in the pond and 27 hours after injection the dye was no longer visible. The two measurements of fluorescence in the pond at 50 and 85 hours after injection indicate that there was very little residual dye left in the pond. These observations are consistent with the residence times calculated for water entering the pond based on a few measurements made over the course of four days, as shown in Table 9. During this period, the pond was observed gradually decreasing in area and volume as the flow entering the pond from the SW28 watercourse diminished. Although the measurements are approximate, they clearly indicate that the residence time on May 10 would have been about five hours. Marcus J. Buck Karst Solutions Page 51

60 Table 9. Approximate residence times calculated for the ephemeral pond at Site 7 during the groundwater trace. Date (mm/dd/yyyy) Time (hr:min) Surface Area (m 2) Volume (m 3 ) Discharge (L/s) Residence Time (hr) 05/09/ : /10/2005 6: /11/2005 9: /12/2005 7: /13/ : The tracer was clearly detected at the SW27 springs and the measured fluorescence just downstream from these springs is shown in Figure 14. The first arrival of the dye was 10 hours after injection. The dye reached the peak concentration of 0.33 µg/l above the background fluorescence at 22.7 hours after injection. Sampling was discontinued 7 days after injection at which point the dye concentration was 0.07 µg/l above background. Although the peak fluorescence was only double that of the background, the measurement noise was low so the data clearly show a well defined breakthrough curve as the dye cloud passed the sampling site. Table 10 presents the surface water data measured at the SW28 watercourse and the various springs located nearby on May 10 during the trace. First, it should be noted that the sum of the discharges from each of the individual SW27 springs was 9.5 L/s less than the flow measured just downstream at Site 46. Only the largest springs were measured as it was impractical to measure every little spring, and some of the discharge was emerging all along the various channels. During the groundwater trace, the individual SW27 springs showed a wide variation in response to the passing dye cloud. The four springs (Figure 13) located to the northwest (SW27B, C, D and A) all showed a positive response with peak values ranging from roughly 0.5 to 0.2 µg/l above background fluorescence. Within this group of four springs, there appeared to be a gradual decrease in peak tracer concentration from spring SW27B located at the northwest to spring SW27A located to the southeast. Furthermore, a positive response was not detected at springs E, F and G and the background fluorescence at these springs was significantly lower than that measured at Sites 46 and 47 along the SW27 watercourse. These observations suggest that Marcus J. Buck Karst Solutions Page 52

61 there are two sets of springs at this site, each fed by groundwater from a different source but with some degree of mixing occurring between them. The conductivity data support this interpretation as well. There is a consistent increase in electrical conductivity from a value of 375 µs/cm at the northwest spring (SW27B) to 416 µs/cm at the southwest spring (SW27G). This gradual rise is consistent with mixing between groundwaters of different composition. Table 10. Surface water data measured at selected sites on May 10, Feature Type is indicated by the following codes: GI1, small intermittent spring; GP1, small perennial spring; GP2, large perennial spring; M, monitoring point along a surface watercourse. Peak [UR] is the peak concentration of the tracer uranine after subtracting the measured background fluorescence. Measurements of flow Q are approximate, generally ± 30%. EC is the specific conductivity. Temp is the water temperature. Site No. Type (code) Peak [UR] (µg/l) Q recharge (L/s) Q discharge (L/s) EC (µs/cm) SW28 M N/A GP1 not detected GI1 not detected * GP1 not detected SW27B GP SW27C GI SW27D GP SW27A GI SW27E GP SW27F GP SW27G GI M (at SW20) GI2 not detected GP1 not detected Allogenic recharge on Amabel plateau (SW28) Discharge at resurgences (SW27B, C, D, A) Total discharge at SW27 spring group (Site 46) Temp ( C) * Measurements were made on May 9 at Site 45 under similar flow conditions Marcus J. Buck Karst Solutions Page 53

62 The electrical conductivities at the first four springs, SW27B, C, D and A, were within 6 µs/cm of that of the sinking stream at SW28. However, the electrical conductivities at the first three springs (SW27B, C and D) were below that of the sinking stream recharge at SW28 on May 10. This is probably a result of temporal variations in water composition. The electrical conductivity measured at SW28 during the previous afternoon was 372 µs/cm, indicating that the electrical conductivity of the recharge was rising. Thus, the water composition at the springs was showing a delayed response to variations at the sinking stream. The mean travel time of the dye calculated from the tracing data for Site 46 was approximately 71 hours. Since the residence time in the ephemeral pond was about 5 hours, the residence time of the dye in the overburden and bedrock aquifers should have been about 66 hours. This residence time is consistent with the observed values for electrical conductivity at these springs and at SW28. The electrical conductivities measured at the remaining springs at SW27E, F and G were all somewhat higher. These springs are probably fed by percolation recharge so the higher electrical conductivities reflect the longer residence time of the groundwater within the overburden and bedrock aquifers. The low tracer concentrations measured at the SW27 springs were due to three factors: 1) the substantial dilution that took place when the tracer entered the pond, 2) the very high dispersion that resulted from infiltration through the overburden beneath the pond, and 3) the loss of dye resulting from decomposition and adsorption. Roughly 10% of the tracer was recovered at the SW27 watercourse at Site 47. This low recovery is expected because: 1) uranine is sensitive to daylight so some photo-decay would have occurred during the time that it resided in the pond, 2) the water in the pond had to infiltrate through a significant volume of glacial sediment before entering the Amabel aquifer so much of the dye would have been lost due to adsorption onto the fine-grained sediment, and 3) much of the dye may have been lost through microbially mediated decomposition, especially while infiltrating through the soil. At the remaining five springs located at Sites 43, 44, 45, 48 and 77, the measured fluorescence remained at background levels and no dye was detected (Figure 12). Therefore, it is concluded that the SW27 spring group is the principal resurgence for the sinking stream at SW28, and within the SW27 spring group, most of the groundwater flow from the SW28 watercourse Marcus J. Buck Karst Solutions Page 54

63 probably resurges at the four closest individual springs (SW27A, B, C and D). Once again, a distributary pattern of flow is exhibited, but the subsurface flow from SW28 is directed to four springs all within 20 m of each other. Several measurements of discharge, electrical conductivity and temperature were made at SW28 and at the SW27 watercourse at Site 46, and these are listed in Table 11. The relative contribution of sinking stream recharge to the SW27 spring group is estimated from this data by comparing the flows at SW28 with the discharge from the SW27 spring group (measured at Site 46). These estimates are only approximate because the actual contribution of sinking stream recharge is controlled by the rate of infiltration through the overburden beneath the ephemeral pond and this is likely to vary somewhat from the flow at SW28. Nevertheless, the relative contribution of sinking stream recharge clearly decreases as the flow in the SW28 watercourse decreases. The relative contribution varied from a maximum of about 50% on May 10 after heavy rainfall to 0% during the summer and fall when the SW28 watercourse is dry. Had measurements been made earlier in the spring when runoff is higher, the discharge at the SW27 spring group would have been dominated by sinking stream recharge. Table 11. Variations in the relative contribution of sinking stream recharge to total discharge at the SW27 spring group. Date (mm/dd/yyyy) SW28 (sinking stream recharge) SW27 spring group (Site 46) Q EC T Q EC T (L/s) (µs/cm) ( C) (L/s) (µs/cm) ( C) Percent Allogenic Recharge 05/14/ /09/ /10/ /28/ /19/ Even though the SW27 spring group receives a relatively large contribution of sinking stream recharge from the SW28 watercourse during wet weather, it still receives much of its recharge from widespread percolation through the soil mantle. In other areas where sinking streams are Marcus J. Buck Karst Solutions Page 55

64 absent, springs must be recharged entirely by percolation recharge. It is concluded that the Niagara Escarpment springs, such as those located at SW27, will not exhibit losses of discharge as a result of the proposed quarrying at the expansion lands. Only those springs located closest to the quarry will exhibit any reduction in discharge, and even these will still be maintained by percolation recharge. 8.0 Investigation at the Duntroon Quarry Expansion Lands Two studies were undertaken at the Duntroon Quarry expansion lands: 1) continuous monitoring of water levels in three boreholes from across the site, and 2) more detailed studies of the SW2A spring and the four boreholes located next to it. 8.1 Water Level Data from BH02-1, BH02-4 and BH03-9 Continuous water level measurements were made in three monitoring wells in 2005 to determine if there are short-term variations in water level, as sometimes occurs in karst aquifers. The three wells were chosen to reflect the range in onsite conditions. Earlier monthly water level measurements by Jagger Hims Limited showed that BH02-4 had the greatest and BH03-9 had the least variation in water level of all the wells on the expansion property. These two wells were monitored as well as BH02-1, where the range in water level was intermediate. Results are shown in Figure 15. The period monitored from early May to late October coincided with the recession from high water levels in the spring to low water levels in the early fall, with an overall fall in water levels of about 5.4 m at BH02-4, 3.5 m at BH02-1, and 0.2 m at BH03-9. Precipitation data for the same period are shown in Figure 16. Major precipitation events usually coincide with rises in the water table of 1-2 cm. These changes occur within hours of the precipitation event, and are most easily visible in the expanded plot of BH03-9 (Figure 16). 8.2 Investigations in the Vicinity of the SW2 Springs There are four monitoring wells located near a pair of karst springs at the southwest corner of the Duntroon Quarry expansion property. These are located well away from the influence of the Niagara Escarpment and these springs are at the head of a watercourse that flows to the Beaver River to the west. As such, they provide an excellent opportunity to investigate the subsurface characteristics of karst development as well as the hydraulic properties of the dolostone aquifer Marcus J. Buck Karst Solutions Page 56

65 away from the Escarpment. Investigations conducted at this site include: 1) continuous monitoring of discharge, electrical conductivity and temperature at the SW2A spring, 2) conductivity and temperature profiling of the four wells, and 3) groundwater traces conducted from each of the four monitoring wells to the SW2A spring under natural flow conditions Site Description Figure 17 is a map illustrating the key features of the SW2 watercourse located at the southwest corner of the Duntroon Quarry expansion lands. The watercourse drains via a culvert beneath Simcoe Road 91 to the wetland located directly to the west of the existing quarry. Jagger Hims Limited monitors the streamflow weekly where it crosses the road at SW2. The watercourse is fed primarily by discharge from two springs. SW2A is a perennial spring located 110 m upstream from the road, and SW2B is an ephemeral spring located 370 m farther upstream. The SW2B spring issues from a small, discrete depression in the overburden in a small valley. This spring only flows for a few days during peak runoff and its discharge may reach 20 L/s or more. For the rest of the year, the flows measured at SW2 are a good measure of the discharge from the SW2A spring since the relative contribution from local surface runoff is negligible. This spring issues from a bedrock conduit beneath a small spring pool (Photo 13). Here, the discharge can reach 35 L/s or more but during extended dry weather it drops to as little as 0.1 L/s. Flows measured at SW2 since 1996 indicate that flows range up to 59 L/s and the lowest base flows observed during summer or fall each year generally range from 0.5 to 1.0 L/s (Jagger Hims Limited, 2007b). Observations indicate that the watercourse occasionally freezes up briefly during winter. These are the only times when the watercourse has not been observed flowing, although there are no observations at the spring to determine if it continues flowing. The flow characteristics at the two springs suggest that they may be interrelated and exhibit an overflow-underflow relationship. The SW2B spring is at a higher elevation, its discharge rises and falls rapidly and it is dry most of the year, characteristics typical of an overflow spring. In contrast, the SW2A spring is perennial with less variation in flow, temperature and electrical conductivity, characteristics typical of an underflow spring. However, a connection between the two springs has not been verified and the SW2B spring could be underdrained by another spring, perhaps at the wetland located at the northwest corner of the expansion property, identified as Unit 2 of the Rob Roy PSW by Stantec Consulting (2005). Marcus J. Buck Karst Solutions Page 57

66 There is a defined channel extending downstream from the SW2A spring to the road. However, a defined channel is generally absent farther upstream. At the SW2B spring, a poorly defined channel extends downstream for 50 m to the north end of a large, shallow depression at Site 16. This depression is roughly 40 m long, 15 m wide and 1.6 m deep at its deepest point near the west end. When the SW2B spring starts to flow, the stream enters this depression and a pond forms. The presence of dolostone outcrops just outside of the depression on the northwest side suggests that overburden is thin beneath the depression. Although the depression may be formed by karst processes, its origin is not entirely clear. Regardless, when the SW2B spring stops flowing, the depression does drain completely over the course of a few days. When the spring discharge is sufficiently high, the depression floods completely and a much larger pond forms that is only a few decimetres deep for much of its extent. A suffosion doline to the south at Site 17 also floods and the excess flow continues on the surface to the west. The stream follows a shallow drainage swale across the field to enter the perennial watercourse just downstream from SW2A. Where the ephemeral watercourse crosses the field, any surface channel that may have existed along the drainage swale would have been eradicated by tilling. There is a second suffosion doline in the middle of the field at Site 18 that is 12 m long, 9 m wide and 40 cm deep. Its morphology has probably been impacted by tilling as well. A tiny depression at the north edge appears to have formed recently and suggests that a little of the streamflow sinks here. There are four boreholes located close to the SW2A spring. Their locations relative to the spring are shown in detail within the inset in Figure 17. Table 12 lists the details of the four monitoring wells. The BH03-9 well was drilled in 2003 and it extends through the entire thickness of the dolostone in the Amabel and Fossil Hill Formations. This hole was cored and the hole was terminated in shale 0.6 m into the Cabot Head Formation. The three remaining wells were rotary drilled without coring in The driller logs indicate that they terminate in grey/blue shalelimestone. However, the depths at the reported dolostone-shale contacts are up to 4.4 m above that measured in BH03-9. As such, these holes may not penetrate through the entire thickness of the Fossil Hill Formation. In addition, the top of each well was grouted and steel casings were installed to depths up to 7.0 m. Therefore, measurements of hydraulic properties, temperature and water chemistry in these wells will not reflect the development of karst in the upper few metres. Marcus J. Buck Karst Solutions Page 58

67 Table 12. Groundwater monitor details for monitoring wells located near the SW2A spring. Designation Diameter (mm) Top of Pipe Elev. Ground Elevation Depth of Well Elevation at Top of Shale Depth of Overburden Depth of Casing BH TW * TW * TW * * Wells logs for the three wells drilled in 2004 are based on drill cuttings and not cores, so the shalelimestone contact reported near the base of the holes may not be at the top of the Cabot Head Formation Monitoring Data at the SW2A Spring and Nearby Boreholes Discharge at the SW2A spring was monitored continuously from April to October Discharge ranged from <0.1 L/s to 35 L/s (Figure 18). Following rain events, discharge generally increased within a period of hours and increases were up to several litres per second. Electrical conductivity and temperature were also measured continuously at SW2A during this period (Figure 19). The rapid fluctuations exhibited in the electrical conductivity data for July are the result of instrumental noise, i.e. some instability in the electronics of the conductivity meter. However, the instrumental noise is negligible in the remainder of the data. The electrical conductivity of the spring water is inversely related to spring discharge. This relationship is normal and reflects the longer residence times of the groundwater in the aquifer during the summer compared to the spring. There are several short-term increases in electrical conductivity. The most marked is the increase from 536 to 579 µs/cm, which coincided with 42 mm of rain between June 13 and June 17, There are smaller increases following 22 mm of rain on May 13-15, 11 mm of rain on May 27-28, and 35 mm of rain on September All these increases reflect the flushing out of longer residence time groundwater in the aquifer matrix. In many karst springs an initial increase in electrical conductivity is followed by a substantial drop; this is absent at the SW2A spring and reflects the absence of sinking streams rapidly recharging the aquifer via conduits. Marcus J. Buck Karst Solutions Page 59

68 There was a gradual increase in spring temperature from 5.5 C in late April to 9.6 C in October. The probe was located in the spring pool next to the conduit orifice to minimize the influence of surface temperatures. Thus, the temperatures should reflect the fluctuations in aquifer conditions that result from heat conduction and groundwater movement. Short-term variations following rain events were minimal indicating that the effects of short-term fluctuations in weather are significantly dampened within the aquifer. Once again, this indicates an absence of sinking streams recharging the aquifer. Much of this signal suppression likely occurs within the overburden mantle above the dolostone aquifer. Furthermore, the peak in spring discharge temperature did not occur until mid-october, about 2 to 3 months after the peak in surface temperatures. This suggests that the groundwater discharging from the SW2A spring has a mean residence time in the order of months during the summer and fall. Correlation of the continuous record of water level at the SW2A spring with the continuous record in BH03-9 and manual measurements in TW04-1, TW04-2, and TW04-3 show a convergence of levels over the summer as spring discharge decreased (Figure 20). BH03-9 and TW04-3 had similar levels, which were consistently lower than levels in the two remaining wells. This suggests that BH03-9 and TW04-3 are better connected by high-permeability pathways to the spring. TW04-1 had the highest water level, indicating the lowest permeability connection to the spring. Electrical conductivity and temperature profiles were taken at the four wells located near the SW2A spring. Initial profiles were taken on May 12, 2005 using a probe with a 24 m cable. A probe with a 60 m cable was used on May 26, 2005, which enabled the profiling to the bottom of the boreholes. A blockage at a depth of 15.3 m in TW04-3 prevented profiling of the full depth of that borehole. Results are shown in Figures for individual boreholes and the results are shown together in Figure 25. Only the data below the bottom of the casing in each well are plotted in the figures. The temperature profiles in the boreholes show that the lower parts of the boreholes were close to isothermal, with temperatures of C reflecting deep aquifer temperatures. The upper parts of the boreholes had lower temperatures that either reflect heat conduction or mixing with colder water recharging the aquifer from the surface. Electrical conductivity values generally Marcus J. Buck Karst Solutions Page 60

69 ranged from µs/cm on May 12 and µs/cm on May 26. The increase observed after 2 weeks reflects the diminished dilution by lower conductivity recharge water. Abrupt changes occurred in temperature and/or electrical conductivity in all four boreholes. These abrupt changes cannot be explained by heat conduction and advection, and must reflect flow into and/or out of the boreholes at specific horizons, such as at elevations of 490 and 502 m in TW04-1, 487 m in TW04-2, 513 and 515 m in TW04-3 and 488, 498, 502 and 511 m in BH03-9. These abrupt changes presumably reflect flow along solutionally-enlarged bedding planes. The contrasts observed in electrical conductivity and temperature between boreholes provides additional evidence for localised flow along fractures. The fracture apertures are calculated from the groundwater tracing data (see Section 8.2.4) Recharge for the SW2 Springs Six karst drainage basins were identified on the Amabel plateau, as indicated in Section 4.2. The SW2A and SW2B springs lie within Basin E and are the likely locations for groundwater discharge from this basin. The perimeter of the basin is defined by the topographic high points that encompass the area surrounding the springs. However, the actual springshed for the two springs may be significantly different from this surface catchment. Jagger Hims Limited has measured flows weekly at SW2 since June Therefore, there is a fairly complete record of flows for six years from September 2000 to September Within this period, about 4 measurements per year were missed, typically around Christmas and early January when the flows are intermediate. Therefore, the calculated mean flow at SW2 should be adequate to calculate the total annual discharge of groundwater from the two springs. The mean flow at SW2 for the six year period was 9.0 L/s. In addition, Jagger Hims Limited (2005, Section 4.2.2) calculated a water budget for the region based on climate data from the Thornbury Slama Station of Environment Canada, located 25 km northwest of the expansion lands. For the 30 Year Normal ( ) they calculated an annual surplus after evapotranspiration of 395 mm. They also calculated the annual surplus for 2003 and 2004 to be 436 and 505 mm, respectively. Observations indicate that there is no surface runoff leaving Karst Basins D and E, except what discharges from springs SW2A and SW2B. Thus, any surface runoff within the springshed is captured underground thereby contributing recharge to the karst aquifer. Thus, the Marcus J. Buck Karst Solutions Page 61

70 total groundwater recharge can be estimated using the value for annual surplus, and the combined size of the springsheds for the SW2A and SW2B springs can be determined using the total annual discharge calculated from the mean flow at SW2. Table 13 indicates the calculated area of the springshed for the likely range of groundwater recharge that may occur for this area. Basin E as defined by topography has an area of only 25 ha, significantly less than the calculated area of the springshed of about 56 to 72 ha. Clearly, the groundwater discharging from the SW2 springs comes from a much larger area than Karst Basin E. The area of the springshed is constrained by the elevation of the land surface. For groundwater to flow to the SW2 springs, the piezometric surface (and the ground elevation) must be above m a.s.l., or the elevation of the SW2A spring. Thus, the area of the springshed can be approximated by the surface topography since only a limited contiguous area lies above that elevation. This indicates that the springshed probably includes a portion of Karst Basin D and the area encompassing Karst Basin E, possibly extending as far west as the Central Wetland on the Highland Quarry property (Azimuth Environmental Consulting, 2006). This wetland is identified as Unit 5 of the Rob Roy PSW by Stantec Consulting (2005). Azimuth Environmental Consulting (2006) conducted continuous water level monitoring with a data logger in OW4, a groundwater monitoring well located roughly 200 m northwest of the SW2A spring near the east edge of the Highland Quarry property. Their data show distinct responses to precipitation events, and during dry weather the water table converged to an elevation of m, the same elevation as the SW2A spring. This indicates preferential flow along solutionally enlarged channels to the SW2A spring and provides additional evidence that the springshed for the SW2A spring extends west of Grey County Road 31. Therefore, the proposed quarries on either side of Grey County Road 31 (i.e., Highland Quarry and Duntroon Quarry expansion) have the potential to impact the SW2A spring. Table 13. The calculated surface area of the springshed for the SW2 springs. Climate Data Groundwater Recharge (mm) Mean Spring Discharge (L/s) Springshed Area (ha) 30 Year Normals Data Data Marcus J. Buck Karst Solutions Page 62

71 8.2.4 Groundwater Tracing to the SW2A Spring Natural gradient tracer testing was carried out from the four boreholes located near the SW2A spring. The substantial discharge from the spring combined with the lack of other springs nearby indicated that there was convergent flow from a large area to the spring. Accordingly, monitoring was only carried out at one location, at the spring orifice. Percolation tests were carried out in the four wells by injecting 17 litres of spring water into the wells and then monitoring the recovery to static water levels. Wells BH03-9 and TW04-3 recovered to static levels in less than one minute, whereas Wells TW04-1 and TW04-2 were much slower. Wells BH03-9 and TW04-3 also had static water levels closest to the elevation of the spring, suggesting that these two wells were connected to the spring by the largest-aperture pathways. Accordingly, the first two tracer tests were carried out at these wells. The ISCO autosampler was used for sampling at the spring. This was supplemented at times by manual sampling. Details of the tracer tests are given in Table 14 and Figure 26. The dyes from the first two injections arrived at the spring in less than one hour and, subsequently, dye concentrations returned close to background values within 3 hours. Dye injections were then made into the two remaining wells. There were good breakthrough curves for three of the four traces. The fourth trace was from Well TW04-1. This well had the highest hydraulic gradient to the SW2A spring so it was anticipated that it would have the slowest groundwater velocity to the spring. It is presumed that the main pulse of dye arrived at the spring after sampling was terminated 112 hours after injection. The traces from BH03-9 and TW04-3 gave groundwater velocities of 38 m/hour and 62 m/hour, respectively. These values are typical of flow along open solutionally-enlarged fractures in karst aquifers. The fracture apertures calculated for these traces are 2.7 mm and 3.7 mm, respectively, calculated using the cubic law. Alternatively, if the flow were through circular channels, then the Hagen-Poiseuille equation gives channel diameters of 4.3 mm and 6.1 mm, respectively. These calculations assume smooth-walled fractures or channels. In reality, the walls are likely to be rough and the actual apertures would be somewhat larger. The traces from TW04-1 and TW04-2 gave apertures that are less than 0.5 mm (Table 14). In the case of TW04-1, the calculated apertures are maximum values and assume that the tracer arrived at the spring soon Marcus J. Buck Karst Solutions Page 63

72 after sampling ended. The range in apertures for the four tests is typical of karst aquifers, where most boreholes intercept solutionally-enlarged fractures with apertures in the range 0.1 mm 10 mm and where aperture widths vary considerably between wells. It is concluded from the tracer tests at the four wells that the aquifer is karstic and that aperture widths in the mm range are common and transmit much of the flow. A few larger apertures likely exist between sinking streams and their resurgences since the sinking streams provide concentrations of groundwater recharge. Larger apertures should also occur immediately upgradient from springs where the groundwater flow becomes focussed, and the largest apertures should occur upgradient from the largest springs. In other areas, the aperture widths should be much like those at the four wells where they range up to a few mm in width. The implications of these conclusions are discussed in the final conclusions (Section 9.0). Table 14. Details of the tracer tests at the SW2A spring on May 12, Parameter BH03-9 TW04-3 TW04-1 TW04-2 Tracer Uranine Phloxine B Phloxine B Uranine Tracer mass (g) Time of injection (hr:min) 14:15 14:50 17:55 18:07 Distance to spring Time elapsed to tracer arrival at spring (hr) Time elapsed to peak concentration at spring (hr) Groundwater velocity from time to peak concentration (m/hr) > > < Head difference to spring Hydraulic gradient Fracture aperture (mm) < Channel diameter (mm) < Reynolds number if fracture < Reynolds number if channel < Marcus J. Buck Karst Solutions Page 64

73 9.0 Conclusions Regional and local investigations were carried out in the study area to determine the nature and extent of karstification. The regional investigation identified the principal karst features in an area that extends approximately 2 km to the north and south of the expansion property. Here, the landscape is dominated by glacial deposits so the karst features are focused in those areas where the overburden is thin, especially along the watercourses or close to the Escarpment brow. The typical diagnostic features of karst such as dolines are not common and many of the features are subtle. However, within 700 to 1400 m of the Niagara Escarpment there is either an absence of surface streams or the surface streams sink. This is typical for karst terrain along the Niagara Escarpment, and six enclosed drainage basins were delineated in this area. Some of the groundwater flow from there discharges to west-flowing creeks but the majority flows to a series of springs discharging from the Amabel aquifer at the Niagara Escarpment. The presence of numerous small to mid-size springs located all along the Escarpment provides further evidence that a karst aquifer has developed in the Amabel Formation dolostone. Four tracer tests were carried out from sinking streams, two on the Amabel plateau and two on the Manitoulin bench. The results were generally similar, with the fastest groundwater pathways to springs having flow velocities ranging from 500 to 3500 m/day, which is typical of groundwater velocities between sinking streams and springs in karst aquifers. The field observations and tracer tests also confirmed that a karst aquifer has developed in the Manitoulin Formation wherever the overburden is sufficiently thin to permit infiltration, and part of the discharge from the Amabel aquifer at the Niagara Escarpment infiltrates into the Manitoulin aquifer. It is concluded that a significant proportion of the discharge at the Manitoulin springs is derived from groundwater recharge on the Amabel plateau. This verifies the importance of the monitoring program established by Jagger Hims Limited (2005, 2007b) at the Manitoulin springs. Local-scale investigations were carried out on the expansion lands. This work included continuous water level monitoring at three wells, electrical conductivity and temperature profiling at four wells, tracer testing from four wells to a nearby spring, and continuous monitoring of stage and electrical conductivity at that spring. The tracer testing from the wells gave velocities that ranged from less than 4 m/day to 1500 m/day, which is typical for tracer tests Marcus J. Buck Karst Solutions Page 65

74 in karst aquifers when the tracer injections are into boreholes. Calculations show that this corresponds to fracture apertures that range from < 0.05 mm to about 4 mm along the traced pathways between the boreholes and the spring. Electrical conductivity and temperature profiling showed distinct changes at a few horizons in the boreholes, suggesting preferential flow along a limited number of horizons in each well. The data from the Amabel Formation are typical of karst aquifers. A conceptual model for the aquifer was developed from the regional and local studies, from the observations in the Duntroon Quarry, and from the borehole measurements reported by Jagger Hims Limited (2005). The uppermost few metres of the bedrock are highly weathered. Below this, the weathering is focussed on a limited number of fractures, typically producing enlargements up to several millimetres in size. Openings may be substantially larger along the flow paths between sinking streams and springs, as well as in the vicinity of the larger springs where groundwater flow is more focused. The following are the conclusions with respect to the proposed quarry expansion: 1) Jagger Hims Limited (2005, 2007a) has anticipated that recharge (injection) wells close to the quarry may be necessary to mitigate the lower groundwater levels predicted in the surrounding areas as a result of quarrying. With the recharge to the aquifer in the expansion lands dominated by distributed percolation, it is anticipated that many small channels and only a much smaller number of conduits (i.e., with a diameter > 1 cm) will be encountered. Thus, the modelling by Jagger Hims Limited generally provides a good representation of the likely discharges at the expansion property. Conduits are most likely to be encountered in the area encompassing the largest springs, at SW2A and SW2B, and it is possible that localized grouting or other mitigation measures might be required there if inflows to the quarry become problematic. The lack of sinking streams or springs elsewhere on the expansion property indicates that there is a much lower probability of encountering large conduits beneath the remainder of the expansion lands. 2) The presence of conduits converging towards the SW2 springs may have the effect of extending the influence of the drawdown zone around either of the proposed quarries (i.e., Highland Quarry or the Duntroon Quarry expansion). The conduit networks surrounding each spring strongly influence the groundwater elevations within their springsheds. However, this Marcus J. Buck Karst Solutions Page 66

75 effect should be largely limited to the extent of the springshed for each of the two springs. The springshed for the SW2B spring is entirely contained within the expansion property. Therefore, drawdown effects should not be exacerbated outside of the proposed quarry as a result of conduits there. On the other hand, the SW2A springshed extends to either side of Grey County Road 31. Within its springshed, the SW2A spring clearly acts as the local base level as indicated by the water elevations observed in the nearby boreholes. As groundwater flow diminishes during the dry season, the groundwater elevations converge towards the elevation of the spring. If only one of the proposed quarries proceeds, then the drawdown effects will likely be propagated along conduits across Grey County Road 31. In this case, injection wells may not be effective at maintaining water levels and localized grouting may be required. However, if both quarries proceed, then the conduits should not exacerbate drawdown effects because the influence of the conduits leading to the SW2A spring should not extend outside of the SW2A springshed, and the springshed is entirely contained within the two proposed quarry properties. 3) The proposed quarries on either side of Grey County Road 31 (i.e., Highland Quarry and Duntroon Quarry expansion) have the potential to impact the SW2 springs. These springs derive their groundwater recharge from a catchment area that extends across portions of each of the proposed quarries. Therefore, quarrying on either side of Grey County Road 31 at either of the proposed quarries will lead to loss of recharge for the SW2A spring. Furthermore, quarrying at either of the proposed quarries may lead to complete loss of discharge from the SW2A spring as a result of the diversion of groundwater flow along conduits intersected by quarrying. 4) The conduits that currently convey groundwater to the SW2A spring may later create permeable pathways between the two proposed quarries, if both quarries proceed. This could cause the final lake levels to equalize in elevation if there is excessive leakage. On the other hand, if the conduits are generally shallow (above 512 m a.s.l.), then there may be little leakage along the conduits between the final lakes. Localized grouting of the intervening bedrock or other mitigation measures might be required if excessive leakage between the quarries becomes problematic. 5) Impacts to the majority of springs along the Niagara Escarpment are likely to be negligible. With the exception of the SW27 and SW11 springs, the Amabel springs located near the Marcus J. Buck Karst Solutions Page 67

76 expansion property derive most of their recharge from widespread infiltration across a broad band of land adjacent to the top of the Niagara Escarpment. It is concluded that these springs will not exhibit any significant loss of discharge as a result of the proposed quarrying at the expansion lands. Only those springs located closest to the quarry will exhibit any reduction in discharge, and even these will still be maintained by percolation recharge. Furthermore, their recharge should be fully restored once lakes are established in the quarries. The SW27 and SW11 springs receive part of their recharge from sinking streams. As indicated by the groundwater tracing, the SW27 springs are the resurgences for the sinking stream at SW28, and during peak flows in the spring they receive much of their recharge from the sinking stream. However, the surface catchment for the SW28 watercourse is outside the expansion lands and will not be affected by the proposed quarry there. Therefore, there will not be any loss of sinking stream recharge at these springs. Furthermore, these springs will continue to be maintained by widespread percolation recharge. The springs most likely to be impacted by the proposed quarry expansion are the SW11 springs. These are the principal resurgences for the sinking stream located at the east end of the expansion property, the SW9 watercourse. Groundwater tracing indicates that after sinking, this stream flows rapidly in the subsurface and resurges at 19 springs located along the Niagara Escarpment, with roughly 90% of the flow resurging at the SW11 springs. Despite the significant component of recharge from the sinking stream, the SW11 springs receive an even greater contribution from widespread percolation recharge on the Amabel plateau, and it is this percolation recharge that maintains these springs throughout the dry season. Therefore, with respect to the proposed quarry at the expansion property, it can be concluded that even with a significant loss of flow in the SW9 watercourse as a result of quarrying, the SW11 springs will still be maintained by the percolation recharge. 6) Jagger Hims Limited (2005, 2007a) proposes discharging some of the excess water from dewatering of the proposed expansion quarry into the SW9 watercourse. This water could be used to maintain water levels in the two unevaluated wetlands located along the watercourse, ANSI A and ANSI B, as required seasonally. The quarry discharge could also be used to sustain flow in the SW9 watercourse to compensate for any loss of surface runoff within its catchment Marcus J. Buck Karst Solutions Page 68

77 during wetter periods. Since the SW9 watercourse sinks in its channel and resurges at the SW11 springs and other nearby springs along the Escarpment, the discharge water can also be used to supplement flows at the Escarpment springs during drier periods. The quarry discharge water would represent only a small fraction of the existing maximum flows in the SW9 watercourse. Any minor thermal effects at the Amabel aquifer springs as a result of the quarry discharge would not affect downstream fisheries because after discharging from the springs, the water temperature rapidly approaches surface temperatures while flowing down the talus slope and because the in-line pond on W. Franks property has a pronounced thermal impact that overwhelms any temperature effects farther upstream (Jagger Hims Ltd., 2007a, b). The quarry discharge water could be used to maintain the net mean discharge at the springs during the period that the quarry is dewatered. Once the quarry is complete and fills with water, some of the excess water from the quarry will flow into the SW9 watercourse seasonally (Jagger Hims Limited, 2007a). Report prepared by: Marcus J. Buck, B.Sc., P.Geo. Marcus J. Buck Karst Solutions Stephen R.H. Worthington, Ph.D., P.Geo. Marcus J. Buck Karst Solutions Page 69

78 References Cited Azimuth Environmental Consulting, Level 2 Hydrogeological Assessment Report Highland Quarry. Unpublished report prepared for M.A.Q. Aggregates Inc, March 31, 2006, Cowell, D.W., Karst Geomorphology of the Bruce Peninsula, Ontario. Unpublished M.Sc. thesis, McMaster University, Hamilton, Ontario, 231 p. Cowell, D.W. and D.C. Ford, Karst hydrology of the Bruce Peninsula, Ontario, Canada. Journal of Hydrology, Vol. 61, p Dreybrodt, W., Principles of early development of karst conduits under natural and manmade conditions revealed by mathematical analysis of numerical models. Water Resources Research, Vol. 32, p Dreybrodt, W., Gabrovšek, F.,and Romanov, D., Processes of Speleogenesis: a Modeling Approach. Karst Research Institute at ZRC SAZU, Postojna Ljubljana, 376 p. Ecoplans Limited, South Waterdown Subwatershed Study, Stage 1 Final Report, Vol. I, xlvi + 534p. and Vol. II (10 Appendices). Field, M.S, A Lexicon of Cave and Karst Terminology with Special Reference to Environmental Karst Hydrology. National Center for Environmental Assessment, U.S. Environmental Protection Agency, Washington. EPA/600/R-02/003, 214 p. Available online at Ford, D.C. and P.W. Williams, Karst Geomorphology and Hydrology. Chapman & Hall, New York, 601 p. Jagger Hims Limited, 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. Unpublished report prepared for Geogian Aggregates and Construction Inc., Vol. 1, 182 p., Vol. 2 (Figures) and Vol. 3 (Appendices). Jagger Hims Limited, 2007a. Duntroon Quarry Expansion, Clearview Township, County of Simcoe, Level 2 Hydrogeological Assessment Addendum, Cumulative Impact Assessment Proposed Expansion and Proposed MAQ Highland Quarry, Computer Groundwater Modelling, Response to Agency Comments. Unpublished report prepared for Walker Aggregates Inc. Jagger Hims Limited, 2007b, Duntroon Quarry Expansion Groundwater and Surface Water Monitoring Program Addendum Lot 25 and Part Lot 26 Concession 12 and Part Lot 25 Concession 11, Clearview Township, County of Simcoe. Unpublished report prepared for Walker Aggregates Inc. Marcus J. Buck Karst Solutions Page 70

79 Meinzer, O.E., Outline of Ground-Water Hydrology. U.S. Geological Survey, Water Supply Paper 494, 71 p. Pluhar, A. and D.C. Ford, Dolomite karren of the Niagara Escarpment, Ontario, Canada. Zeitschrift für Geomorphologie, Vol. 14, p Romanov, D., Gabrovsek, F., and Dreybrodt, W., The impact of hydrochemical boundary conditions on the evolution of limestone karst aquifers. Journal of Hydrology, Vol. 276, p Romanov, D., Gabrovsek, F., and Dreybrodt, W., Modeling the evolution of karst aquifers and speleogenesis. The step from 1-dimensional to 2-dimensional modeling domains. Available online at Scanlon, B.R., Mace, R.E., Barrett, M.E., and Smith, B., Can we simulate flow in a karst system using equivalent porous media models? Case study, Barton Springs Edwards Aquifer, USA, Journal of Hydrology, Vol. 276, p Stantec Consulting Ltd., Duntroon Licence Expansion Level 2 Natural Environment Technical Report. Unpublished report prepared for Georgian Aggregates & Construction Inc., October 7, White, W.B., Geomorphology and Hydrology of Karst Terrains. Oxford University Press, New York, 464 p. Worthington, S.R.H., Davies, G.J., and Ford, D.C., Matrix, fracture and channel components of storage and flow in a Paleozoic limestone aquifer, in Wicks, C.M., and Sasowsky, I.D., eds., Groundwater flow and contaminant transport in carbonate aquifers: Rotterdam, Balkema, p Worthington, S.R.H., and Smart, C.C., Empirical determination of tracer mass for sink to springs tests in karst. In: Sinkholes and the Engineering and Environmental Impacts of Karst; Proceedings of the ninth multidisciplinary conference, Huntsville, Alabama, Ed. B.F. Beck, American Society of Civil Engineers, Geotechnical Special Publication, No. 122, p Marcus J. Buck Karst Solutions Page 71

80 Karst Investigation of the Duntroon Quarry Expansion Lands October 3, 2007 Figures (Located in back pocket) Figure 1. Regional map of karst features and surface water monitoring sites. Figure 2. Discharge by magnitude of 46 gauged springs in the Amabel Formation and 42 gauged springs in the Manitoulin Formation. The springs have modest discharges, ranging from magnitude 4 ( L/s) to magnitude 7 ( L/s) using the spring classification of Meinzer (1923). Marcus J. Buck Karst Solutions Figures, Page 72

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104 Appendix A: Glossary of Karst Terms The following definitions are intended to aid the reader in understanding the terms used in the text, and they are not necessarily universal. In some cases, the use of the terms has been restricted to be relevant or appropriate to the context of this study, or the definitions are those of the authors as they have used them in the text. The United States Environmental Protection Agency has prepared an extensive lexicon of cave and karst terminology (Field, M., ed., 2002) that can be downloaded free from their website ( Some of the definitions used here were derived from those in the EPA document, although they are all modified. bare karst: cave: channel: conduit: conduit flow: doline: dry valley: A karst where the soil is thin or absent and karst landforms occur on the exposed bedrock. A natural hole in the ground that is large enough for human entry. In the context of hydrology, a cave is a conduit with dimensions that are large enough for human passage. (karst channel) Dissolutional voids in the bedrock that form continuous flow paths with a minimum diameter of about 1 mm that is sufficient to permit rapid groundwater flow velocities. Flow is generally laminar in smaller channels with a diameter of less than 10 mm. (karst conduit) Relatively large dissolutional voids in the bedrock that form continuous flow paths with a minimum diameter of about 10 millimetres. Although flow may be either turbulent or laminar, flow velocities in karst conduits are relatively rapid. Worthington et al. (2000) used empirical data to show that flow velocities in karst conduits range from about to 1 m/s, with a mean velocity of m/s. Groundwater flow within conduits. Flow may be either turbulent or laminar. See conduit. A topographically closed depression, commonly circular or oval in plan view. Five genetic types are commonly recognised, though many dolines have more than one mechanism of formation. Collapse dolines are caused by the collapse of bedrock into an underlying void, and often have steep sides. Solution dolines are caused by solution of the bedrock and centripetal flow to a central conduit drain. Suffosion dolines are caused by the subsidence or down-washing of unconsolidated sediments into an underlying conduit drain in bedrock. Subsidence dolines are caused by the subsidence of bedrock above a solution void. Buried dolines are ancient dolines that have been filled in by unconsolidated sediments, such as glacial deposits. A valley that lacks a permanent surface stream. In karst, dry valleys form initially by normal fluvial processes but as karst develops, surface runoff is eventually captured underground, at which point the valley becomes inactive or relict. Marcus J. Buck Karst Solutions Appendix A, Page 96

105 epikarst: fluviokarst: holokarst: karren: karst: karst aquifer: mantled karst: recharge: resurgence: runnel: sinkhole: The upper portion of the bedrock, beneath the soil, that is characterized by extensive fracturing, and enhanced solution and weathering. Significant water storage and transport occur in this zone. A landscape with both fluvial and karst landforms. The dominant landforms are valleys cut by surface streams, but the surface streams are captured underground as the karst develops. Fluviokarst commonly forms where karst is mantled by thick, impermeable soil. Surface streams initially perched on the soil are eventually captured underground as they erode through the soil mantle and come into contact with the bedrock. A karst landscape with little or no surface runoff or streams, and often characterized by well developed karst landforms. Small-scale dissolution features on soluble rocks, such as limestone and dolostone. A landscape that forms as a result of solutionally enhanced secondary permeability in the bedrock, and characterised by rapid groundwater flow velocities and the occurrence of solution features such as karren, dolines, bedrock channels, caves, sinking streams, and springs. An aquifer with solutionally enhanced secondary permeability, chiefly characterized by rapid groundwater flow velocities and the occurrence of continuous flow paths along channels that direct groundwater flow from recharge areas to springs. A karst where the bedrock is covered by unconsolidated sediment. The process of the addition of water to groundwater. Reference is made to two types of recharge in the text. Sinking stream recharge is the concentrated recharge that is derived from surface streams that sink, either at discrete points such as in dolines, or more gradually along a losing reach. In the local setting, the surface streams are perched upon glacial sediment that isolates the stream water from the karst aquifer until the water sinks. Percolation recharge is the widespread and diffuse infiltration of precipitation either directly into the bedrock, or through the glacial sediment where the karst is mantled. Sinking stream recharge exhibits wide variations in rate and chemistry in response to precipitation and it infiltrates rapidly. In contrast, percolation recharge exhibits much less variation in rate and chemistry in response to precipitation and it infiltrates slowly. A spring principally fed by one or more sinking streams. Resurgences are characterised by a wide range in discharge and chemistry, and the water typically becomes turbid after heavy rain. A groove on the surface of the bedrock formed by dissolution. Synonymous with doline (sinkhole is chiefly used in the United States). A cover collapse sinkhole is a suffosion doline that forms by sudden collapse of unconsolidated sediment into an underlying cavity formed by soil piping above a solutionally widened drain in the bedrock. A cover subsidence sinkhole also forms by soil piping and downwashing of sediment into a solutionally widened drain in the bedrock but the overlying sediment gradually subsides. Marcus J. Buck Karst Solutions Appendix A, Page 97

106 sinkpoint: sinking stream: soil piping: spring: A discrete location where a surface stream sinks underground into a conduit. A surface stream which sinks underground, either at a sinkpoint, or along a losing reach where flow is lost by gradual infiltration into the ground. The transport of material through pipes in unconsolidated sediments. The soil pipes are typically round and a few mm to a few cm in diameter but may be larger. In mantled karst, soil pipes can permit rapid infiltration of surface water into the underlying karst aquifer. A natural outflow of groundwater to the surface. Marcus J. Buck Karst Solutions Appendix A, Page 98

107 Appendix B: Photographs Contents Page Photos Photos Photos Photos Photos Photo Marcus J. Buck Karst Solutions Appendix B, Page 99

108 Photo 1. Group of suffosion dolines located to the west of SW28 watercourse at Site 9. The ephemeral pond occasionally floods to the edge of these dolines when runoff is high. Photo 2. Suffosion doline at Site 8 drained by a large soil pipe at the base. This doline formed by soil subsidence and downwashing of fines into an underlying karstic drain. Photo 3. A suffosion doline at Site 10 that formed by sudden collapse of the soil into an underlying cavity. The doline is 1.8 m deep with slightly overhanging walls. Such dolines are also called cover collapse sinkholes. Photo 4. A sinking stream at Site 173 at the west edge of Grey County Road km south of the Duntroon Quarry. The stream emerges from the culvert in the foreground and sinks as it crosses the field in the background. The stream likely resurges 150 m to the south at a spring at Site 174. Photo 5. The SW28 watercourse in the foreground flows into the ephemeral pond in the background where it sinks through the overburden. The stream resurges 300 m to the east at the SW27 springs. Photo 6. Two hours after the uranine injection at SW28, the dye cloud had migrated partway across the pond as it was displaced by new water entering from the watercourse. The estimated residence time in the pond was 5 hours. Marcus J. Buck Karst Solutions Appendix B, Page 100

109 Photo 7. The uranine injection into the SW9 watercourse a short distance upstream from SW9. The sinking stream resurges at the SW11 springs and a number of other springs located along the Niagara Escarpment to the east. Photo 8. The phloxine B injection into a small sinking stream on the Manitoulin bench just downstream from the water supply system at SW10. The stream resurges at the SW11 springs and possibly at other springs along the Manitoulin escarpment. Photo 9. Small intermittent spring emerging from a soil pipe at Site SW27g. The spring is at the elevation of the Amabel Formation not far below the crest of the Amabel escarpment (visible in the background). Photo 10. A dug well located at an Amabel spring at Site 147. This small perennial spring issues from overburden at the elevation of the Amabel Formation along the Amabel escarpment slope. Backpack for scale. Marcus J. Buck Karst Solutions Appendix B, Page 101

110 Photo 11. Small perennial spring at Site 77 emerging from a bedrock conduit in the Amabel Formation. A pond was once excavated just downstream but the stream has since eroded through the earth dam and the pond is now drained. Photo 12. Small spring issuing from the base of the talus slope along the Amabel escarpment at Site 39. The stream continues flowing across the Manitoulin bench but gradually infiltrates into the overburden over a distance of over 100 m. Photo 13. SW2A spring with the outlet channel in the background. The water emerges from a bedrock conduit at the base of the pool to the right of the staff gauge (vertical steel pipe). Photo 14. View looking upslope towards a small perennial spring at Site 29. The spring seeps from the overburden at the base of the 5-metre high erosional escarpment that has formed near the top of the Manitoulin Formation. Photo 15. Ditch extending from an intermittent pond in the distant background (not visible) to where it ends abruptly in the foreground at Site 6. Photo 16. Relict fluvial gully that once drained the Amabel plateau in Nottawasaga Lookout Provincial Park. The view is upstream from the crest of the Amabel escarpment. Any surface runoff now drains into dolines on the plateau. Marcus J. Buck Karst Solutions Appendix B, Page 102

111 Photo 17. The SW2B spring emerges from a small depression in the overburden located in this small valley. At the time, about 20 L/s was discharging from the ephemeral spring. In the distant background, the stream enters a large ephemeral pond occupying a relatively large depression. Photo 18. A derelict concrete cistern constructed at a small perennial spring at Site 159. Spring water still issues from the talus and some of the flow is captured in a bucket and directed into the hose. A small bedrock scarp is just visible at the crest of the Amabel escarpment in the background. Photo 19. A dug well located at a small spring near the crest of the Manitoulin escarpment at Site 52. The steel cistern collects water, which then feeds the hose visible in the foreground. Photo 20. The Hobo weather station used to monitor temperature, relative humidity, rainfall and solar radiation during the spring, summer and fall of It was located at the east end of the expansion property. Marcus J. Buck Karst Solutions Appendix B, Page 103

112 Photo 21. The north wall of the Duntroon Quarry. The upper few metres of the dolostone are well fractured and distinctly weathered. Many of the fractures are parallel to bedding and a few extend for more than 100 m. Beneath this, the dolostone is only cut by a few prominent vertical fractures that are often visible from rusty weathering. Otherwise, weathering in the lower dolostone is distinctly less and it retains a blue-gray colour. Photo 22. The south wall of the Duntroon Quarry at the middle settling pond (Site 21). Here the interreefal dolostone is well fractured parallel to bedding, although fracturing and weathering is most pronounced in the upper few metres. A large spring issues from various points along a prominent fracture just above the pond, with most of the discharge occurring close to the large earth dam at the right. The remaining discharge is over a width of about 10 m toward the left side of the photo. Photo 23. Small intermittent springs issuing from various fractures in the wall of the Duntroon Quarry at Site 22, located below the asphalt plant. The springs are highly visible because of the dark green algae growing on the moist rock. Photo 24. Small intermittent spring located at Site 24 below the asphalt plant in the Duntroon Quarry. The spring issues from bedding planes at the base of the upper fractured zone. Marcus J. Buck Karst Solutions Appendix B, Page 104

113 Photo 25. View across the centre of Karst Basin D during the spring melt in This is one of two closed drainage basins at the expansion property. There are no surface outlets for this basin and any surface runoff collects in two shallow pools at the lowest elevation, visible in the centre of the photograph. The water in the pools gradually infiltrates into the overburden. The internal drainage and lack of surface watercourses suggest that surface water infiltrates readily into the underlying karst aquifer. Marcus J. Buck Karst Solutions Appendix B, Page 105