This report was prepared by exp Services Inc. for the account of the Royal District Planning Commission (RDPC).

Transcription

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2 Legal Notification This report was prepared by exp Services Inc. for the account of the Royal District Planning Commission (RDPC). Any use which a third party makes of this report, or any reliance on or decisions to be made based on it, are the responsibility of such third parties. Exp Services Inc. accepts no responsibility for damages, if any, suffered by any third party as a result of decisions made or actions based on this project. The maps provided in this report include representations of a GIS based digital map product produced by exp; these maps do not represent the level of detail present in the digital product. It is a representation of a GIS based digital mapping product and proprietary to exp Services Inc. Disclosure shall not be construed in any way as granting a license or any other right to the recipient. Royal District Planning Commission has reproduced these GIS based maps and the accompanying information with the expressed license and permission of exp. Any use or reproduction of this material without the express permission of exp is strictly prohibited. Neither Royal District Planning Commission nor exp assume any responsibility for unauthorized use or disclosure. i

3 Table of Contents Page Chapter 1 Introduction Introduction... 2 Chapter 2 Methodology Methodology Task 1 Project Meetings Task 2 Information Compilation, Review and Mapping Sources of Data Digital Mapping Preparation Data Quality Task 3 Hydrogeological Setting Task 4 Recharge Areas Task 5 Aquifer Vulnerability Assessment Ground-truthing A Living Model, Assumptions and Limitations Chapter 3 Description of Study Area Description of Study Area Geology Topography Climate Chapter 4 Results Results RDPC Consultation Hydrological Setting Hydrostratigraphic Units Bedrock - Igneous Plutonic HU (Ip HU) Bedrock - Igneous Volcanic/Metamorphic HU (Ivm HU) Bedrock - Horton HU (H HU) Bedrock - Windsor/Mabou HU (W/M HU) Bedrock - Cumberland HU (C HU) Bedrock - Structural HU (S HU) Surficial - Till HU (T HU) Surficial - Sand/Gravel HU (S/G HU) ii

4 4.2.2 Hydrological Regions and Districts Highland Region Mountain Flank Region Foothills Region Lowland Region Recharge Areas Aquifer Vulnerability Assessment Chapter 5 Summary and Recommendations Summary and Recommendations Summary Recommendations Chapter 6 Acknowledgments Acknowledgements Chapter 7 References References exp Quality System Checks Project No.: MON A0 Date: May 17, 2012 Type of Document: Final Revision No.: 0 Prepared By: Fred Baechler, P.Geo. Reviewed By: John Sims, M.Sc., P.Eng., P.Geo. iii

5 List of Tables Page Table 4-1: Recharge Areas by Region and District Table 4-2: Ranges of Drastic Rankings within topographically defined Recharge Zones iv

6 List of Figures Page Figure 1.1 Site Location Plan... 3 Figure 2.1 Science Requirements for Groundwater Sustainability... 5 Figure 3.1 Study Area Landscape Figure 4.1 Highland Hydrological Region 3-D Block Diagrams of Districts Figure 4.2 Mountain Flank Hydrological Region 3-D Block Diagrams of Districts Figure 4.3 Lowland Region 3-D Block Diagrams of Districts v

7 Chapter 1 Introduction 1

8 1 Introduction The Royal District Planning Commission (RDPC) is interested in the protection of the potable groundwater resource within their planning jurisdiction and has identified the requirement for an Aquifer Vulnerability Study to assist in this objective. The regional location of the subject property is shown on Figure 1.1. It is understood based on boundary information provided by RDPC that the planning district is 608,634 hectares in area. To assist in addressing their objectives, RDPC retained exp Services Inc. (exp the new identity of ADI Limited) to provide Professional Services to complete a regional scale aquifer vulnerability study. RDPC s primary objective in commissioning the study is to further in the general education and awareness of the region s hydrologic resources to the benefit of decision makers within RDPC s jurisdiction. The work supplements ongoing initiatives in RDPC s Talking About Water series that can be found at In this context, the study as currently developed is not intended to be used as a definitive tool for planning policy analysis. It is important to recognize that a fundamental characteristic of all approaches to ground water vulnerability assessment is uncertainty, either in the method itself or in the data it uses. Consequently the prediction of groundwater vulnerability is an imprecise exercise, and one that is subject to continued review and updating as additional information becomes available. In this context the regional phase study is intended to serve as a high level model. Boundary lines of the respective aquifer vulnerability areas identified within the scope of the current work are not exact. Consequently, the zones are intended to serve as one aspect in consideration of regional water resource protection, and should not be used as a definitive tool by which to manage individual properties or development proposals. As additional field data are collected the regional scale model can be adjusted and recalibrated to more local scale. In this sense, the current work represents a living model, which is well suited to an adaptive management philosophy to enhance water resource protection education, and RDPC s objectives. This Technical Summary Report outlines the general approach and findings of the regional aquifer vulnerability study completed by exp. It is important to note that the key deliverable for the project was the compilation and delivery of a GIS based digital archive. As such, the Technical Summary is an overview of the results of the work, and the reader is referred to the actual digital database for further details concerning database aspects and results of the work. The Technical Summary Report is organized into seven sections with related information (e.g. representative figures) appended. An account of the study methodology is provided in Section 2 followed by a general site description in Section 3; a discussion of the project aquifer vulnerability assessment results in Section 4; summary and recommendations in Section 5; and acknowledgments in Section 6. Project references are listed in Section 7. Supplemental information includes representations (Appendix A) of the digital mapping results which constituted a key deliverable of the project. 2

9 3 Royal District Planning Commission

10 Chapter 2 Methodology 4

11 2 Methodology This study of recharge areas and their vulnerability within RDPC s jurisdiction exemplifies a move toward sustainable water resource management. In their 2009 publication on The Sustainable Management of Groundwater in Canada, The Expert Panel on Groundwater noted that the growing and emerging threats to groundwater require that Canada develop a more sustainable management strategy to protect this vital resource. They outlined four investigative components that when integrated and managed appropriately, should lead to credible and defensible interpretations of groundwater flow systems. This in turn will enable decision-making on issues pertaining to groundwater and land use that contribute to the protection and sustainable utilization of the resource. The Expert Panel s four-components and connection to the decision-making process can be represented by a pyramid (Figure 2.1). Figure 2.1: Science requirements for groundwater sustainability This model was applied to the RDPC assignment as follows: Database Development and Management: A comprehensive geological, hydrogeological and hydrological data base was developed to support refinement of the three subsequent related components of the framework, i.e. Geological Framework, Hydrogeological Regime, and Groundwater Models. Database development is outlined in section 2.2. Geological Framework: The development of a sound understanding of the subsurface geology is one of the most critical steps in managing groundwater. This involves understanding the geological processes responsible for the original deposition of the rock or sediment framework. Since drilling to obtain the necessary information is expensive and because parameters that control groundwater movement can vary considerably over short distances, an understanding of the geological setting and correlation with similar settings can provide a defensible and costeffective means of interpolating hydrogeological measurements across broad areas (discussed in Section 2.3). 5

12 Hydrogeological Regime: This component includes combining the geological units that have similar characteristics for controlling the occurrence, quantity and quality of groundwater, into what are termed Hydrostratigraphic Units (HUs), (discussed in Section 2.3). These are the building blocks to develop the Groundwater Models noted below. Groundwater Models: The HUs were combined in various numbers and orientations to describe different Hydrological Settings. These included defining Hydrological Regions and Districts for which conceptual models were developed (with the use of 3-D block models), to define what is known about 1) groundwater flow, 2) recharge and 3) vulnerability of recharge areas. 2.1 Task 1 Project Meetings A start-up meeting was held with key members of the exp Project Team and representatives of RDPC to discuss project items including but not limited to the following: Review project objectives/plan/methodologies/schedules/priorities; Determine location and nature of readily available information sources; Identify data gaps and data quality issues. A primary aspect of the first meeting was to consult with RDPC to further define the scope, schedule, and budget of the first phase, and discuss direction of possible subsequent phases once the regional study was completed. 2.2 Task 2 Information Compilation, Review and Mapping Sources of Data Data used in the project were sourced from several provincial government departments and agencies, the Federal Government, the University of New Brunswick, the Royal District Planning Commission, and from exp s internal geospatial data inventory. The following datasets were the most relevant to the project: Bedrock Geology Provincial and 1:50,000 New Brunswick Department of Natural Resources (NBDNR) Surficial Geology Provincial - NBDNR Topography road network, watercourses, wetlands, etc. Service New Brunswick (SNB) Topography 1:50,000 scale Natural Resources Canada (NRCAN) Elevation Data including shaded relief images - University of New Brunswick (UNB) Watersheds 1:10,000 - NB Aquatic Data Warehouse Infrastructure powerlines, pipelines, roads, etc. - SNB Ecodistrict Climate Summary Agriculture and Agri-Food Canada (AAFC) Well Head Protection Areas New Brunswick Department of Environment (NBDENV) 6

13 A substantial number of data layers were derived from analytical operations on the above data sets. Of these layers the most significant are considered to be: Bedrock Hydrostratigraphic Units Surficial Hydrostratigraphic Units Structural Hydrostratigraphic Units Hydrological Regions Hydrological Disticts Aquifer Recharge Areas Vulnerability of Recharge Areas The derived data layers have been provided to the RDPC in ESRI Shape File format Digital Mapping Preparation GIS technology, other Geomatics software such as Terrain Analysis (surface interpolation and gridding), and Digital Image Processing Software were employed to construct a geospatial database comprising data layers obtained from the RDPC as well as other public and private sources. The RDPC provided a comprehensive database covering the RDPC area of interest. However, exp s decision was to use the New Brunswick 1:10,000 watershed boundaries that extended beyond the RDPC boundaries as the basis for data compilation as these represent natural hydrological boundaries. The extended area can be seen as the extent of the watersheds identified in Figure 1.1. Project analysis was conducted using this area and derived layers such as hydrostratigraphic units, hydrological districts/regions, and aquifer vulnerability areas were clipped to the extent of the RDPC boundaries afterward. Although the data compilation and modeling was based on an area larger than the RDPC jurisdictional boundaries, the results of the modeling and model inputs have been reduced to match the boundary provided to exp by the RDPC. This boundary including land and water bodies covers 608,634 hectares. In order to facilitate modeling and analysis, the municipalities of Sussex and Hampton were included as part of the RDPC area (resulting in 612,102 hectares). This area was subsequently revised through the elimination of all waterbodies and watercourses leaving a final aerial extent of 582,022 hectares. It should be noted that the municipalities of Hampton and Sussex despite not being part of the RDPC planning jurisdiction have been included in the analysis. These areas represent a relatively small percentage (approximately one-half percent) of the total area. Given the scale of the project as well as the level of error present in some of the data layers it is exp s opinion that the differences in the areal extent are relatively insignificant. Data layers such as watersheds, watercourses, waterbodies, wetlands, and other topographic data layers covered the entire area of interest (based on watershed boundaries) and required marginal processing. However, key data layers such as bedrock geology and surficial geology required extensive processing. Bedrock geology at a provincial scale, 1:250,000 scale, and 1:50,000 scale is available in ESRI Shapefile format from the NBDNR. The 1:50,000 scale bedrock geology data set was used in order to provide maximum accuracy and precision (within the constraints of the available database) and to minimize differences between the topographic base map used in the RDPC layers and the base used in the geology map series. However, due to inconsistencies in unit boundaries and descriptions between some 1:50,000 map sheets for the area of interest, the geology in certain areas was derived from available 1:250,000 scale geology maps. Surficial geology for the area was sourced from NBDNR. Due to the lack of large scale surficial geologic mapping in a GIS compatible digital format, the provincial scale surficial mapping was used for the project. While lacking in detail and accuracy (when compared to larger scale maps) this provincial scale data layer provided continuous and consistent coverage of the area of interest. 7

14 Once datasets were compiled, GIS technology was used to perform analytical operations enabling evaluation of spatial correlations among the data layers, patterns and trends, and the derivation of new data layers. Based on available data layers, a data processing model was designed to produce the final Aquifer Vulnerability Mapping product. This model included the sequential generation of Hydrostratigraphic Units (from surficial, bedrock geology, and structural data), Hydrological Districts and Regions (from a combination of topography and hydrostratigraphic units), Areas of Recharge and Well Head Protection Areas Data Quality Geospatial data processing technologies support the development of complex models such as those required in this study. However, the quality of these models is to a large extent dependent on the quality of the data layers that are used in the models. Given that one of the primary requirements of this project was the delivery of data in a GIS format compatible with the system used at the RDPC, all data for the project was derived from existing digital data sources in a GIS compatible format. While other data sources such as the hardcopy bedrock geology and surficial geology provide greater content and detail, the scope and budget did not support the conversion of these data layers to a high quality geospatial database prior to analysis and modeling. The quality of the data sourced from the different agencies and organizations varied considerably. In general, all of these data sets contained some degree of both spatial and attribute errors. Further to this, the topography base (watercourses, waterbodies, and boundaries) that was utilized in each map source (bedrock geology at 1;50,000, 1:250,000, provincial geology, and surficial geology) differed with respect to each other. There were also inconsistencies in the geologic unit names within and between each 1:50,000 map sheet as well as differences in boundaries between adjacent sheets. The provincial scale surficial geology map used for the project contained only cryptic codes for the surficial units and required significant processing within the GIS environment to bring it to a level suitable for inclusion in the modeling. Apart from expected spatial inaccuracies that occur in almost all mapping, certain data source aspects (e.g. attribute coding, lithologic unit boundary discrepancies) resulted in considerable expended project time in data set processing. In general, large scale topographic data was of high quality compared to the large scale (1:50,000) bedrock geology. The latter being arguably the most important data layer but found to contain the majority of spatial and attribute errors. Despite exp s efforts to correct the most significant problems there were still remnant spatial and attribute errors in the data layers which affected the analysis and modeling within the GIS environment. However, given the regional nature of the assessment these inherent errors in the data are not considered significant for the role(s) (e.g. education and consultation with stakeholders) these maps are understood to be intended for use by RDPC at this time. 2.3 Task 3 Hydrogeological Setting The key to delineating recharge zones and their vulnerability was first to develop a conceptual model of how the groundwater system worked and varied between different parts of the study area. This was accomplished by mapping out Hydrological Settings. To define these Settings a three phase approach was followed: 1) Delineating all geological units; 2) Condensing geological units into Hydrostratigraphic Units (HUs); and 3) Combining the HUs to define Hydrological Settings (Regions and Districts). 8

15 This approach was constrained in part by the minimal amount of pertinent and available data throughout the study area. As a result it was necessary to accommodate the limited availability of data by extrapolating from other representative areas (e.g. Moncton area based on Maritimes Groundwater Initiative, GSC 2005; and Cape Breton Island based on Baechler et al., in progress). The bedrock and surficial geological groups mapped by others (e.g. NBDNR bedrock mapping) within the study area were assessed in terms of their ability to define the occurrence, quantity and quality of groundwater, and then grouped into respective HUs. The HUs can be considered as building blocks to create different Hydrological Settings. The unique character of each Setting was mapped out by defining areas with characteristic type, number and orientation of HUs, coupled with climate and topographic relief. This approach emphasizes those aspects of a Settings natural history that are representative, rather than rare; it is concerned with the common and conspicuous. The area was therefore divided into larger Hydrological Regions, and then further subdivided into smaller Hydrologic Districts. One of the difficulties in any groundwater protection mapping approach, is the depth boundary for delineating groundwater resources. Limited information is available in the study area on groundwater resources at depth. Therefore, rather than defining groundwater resources by water quality for human use, the approach was keyed to that portion normally drawn on by man. In this context, although it is recognized that individual water supply wells within the region can be deeper, for this assignment a depth of 200 m was assumed as this in a general sense can be considered the depth interval that includes the unconsolidated surface deposits and the upper (nearer surface) typically more fractured bedrock where surface water yielding intervals for potable use and development are generally found. 2.4 Task 4 Recharge Areas Recharge to the Active GFS can take many pathways including: Pathway 1: downward (from infiltration of precipitation); Pathway 2: upward (from deep crustal scale flow systems); Pathway 3: laterally (from infiltration along stream banks or sea coast due to influent conditions, tidal fluctuations and/or rising sea level); Pathway 4: pressure-focussed recharge (from large man-made impoundments); Pathway 5: seepage loss from subsurface infrastructure (storm/sanitary sewers); Pathway 6: quick recharge (from improperly constructed or old water wells, mineral exploration wells and/or active/abandoned underground mine workings) and/or; Pathway 7: artificial recharge (irrigation on agricultural lands). This study only gave consideration to dryland diffuse recharge through Pathway 1. This is defined as water that infiltrates the soil from rainfall, passes through the root zone, soil matrix and layers of unconsolidated sediments, and eventually reaches the regional aquifer, which usually consists of fractured bedrock. In the case of unconfined conditions the recharge is the amount of water reaching the regional water table. This focuses on infiltrating water in excess of soil moisture deficit, evapotranspiration, and rerouting though the shallow storm water flow system. Other constraints were then applied to delineate the recharge zones, including the following: 1) All ground surface is essentially a recharge zone for groundwater s Quick-Flow-Field (QFF) that operates over approximately 1 to 3 meters below ground surface. The QFF primarily controls storm water runoff by diverting some portion of the infiltrating recharge down topographic gradient 9

16 to recharge the nearest stream. While this is important for aquatic ecosystems, discussions with the RDPC indicated that it was not considered to be important for this study, which focuses on recharge to aquifers. 2) The next stage was to define which HUs would be considered as aquifers ; or those HUs that could contribute groundwater of sufficient quantity and quality for use by humans. Based on discussions with the RDPC this definition was to include all HUs capable of meeting not only larger yield requirements for commercial, industrial and municipal needs, but also those for domestic dwellings, without the need for extensive treatment. The decision was then made to include all bedrock HU s, and the Sand/Gravel HU of the overburden. Areas of the Windsor/Mabou HU where major evaporite deposits are present were considered for removal. However, no large areas existed and so this HU was considered as an aquifer for this Regional assessment. Known areas of hydraulically active karst, usually associated with such evaporite sequences, which could enhance recharge were also not outlined. Areas of known natural mineralization, while possibly having an impact on water quality, were not removed at this time. While the Albert Formation of the Horton HU is known to be hydrocarbon bearing and of low permeability and generally poor water quality, it was considered to still be capable of meeting domestic demands and therefore not removed from consideration. It is recognized that aquifers can exhibit a range from unconfined water table conditions to semi-confined/confined artesian conditions. Given the absence of detailed field information throughout the study area, all types were included as aquifers. Their variation in vulnerability to contamination was handled on a preliminary basis through the DRASTIC assessment. It is expected that a more detailed level of assessment will be a necessity if site specific studies are desired within areas of interest. As RDPC moves forward in refining the objectives of the study and application to site-specific and local areas within the RDPC district, further consideration as to whether these units should be considered as aquifers, and what level of protection is warranted can be given. 3) Only unconfined and semi-confined aquifers of both fractured and unconsolidated media were considered. Aquifers confined at depth by overlying deposits were not incorporated, except if and where they subcrop/outcrop. However, most of this type of system (including Mountain Block and Mountain Front Recharge) is incorporated within what will be termed the Mountain Flank Region, which is highly complex geologically. To date there is no information that identifies potentially large lithologic aquifers that dip steeply to depth and where recharge areas could be identified at surface. The only such systems defined to date and within the scope of this study are the fault aquifers, which are discussed below. 4) All Well Head Protection Areas (WHPA) were considered as recharge zones regardless of their position in the landscape, given that pumping could alter flow fields and that they are important areas for protection. This did not include source water protection watersheds for surface water withdrawals, as the natural groundwater flow field should still apply. 5) All Sand/Gravel Aquifers were considered as recharge zones, including those in lowland areas, and therefore important for protection. 6) All mapped faults were considered to be hydraulically active for a distance of 500 m on either side of the fault trace. While hydraulically active, they were not considered to be structurally active. Although an active earthquake region is present with epicentres in and immediately adjacent the 10

17 study area, the magnitudes are low ranging from 2.4 to 3.6. Given the potential complexity of groundwater flow in these zones it was assumed that their subcrops were all available for recharge. It is expected, but not as yet confirmed, that a number of the Gorges in the Highland Regions are also fault controlled through transform faults, but they are not mapped. Further major bedding plane faults (e.g. such as the Penobsquis Thrust Fault that is interpreted to cut through the base of the Windsor) may be present but have not been identified on regional geological mapping. For the purposes of this mapping program it was assumed that such faulting, unless otherwise indicated from existing geological map sheets, is not present. It is important to note that fault traces indicated on maps (as for general geological boundaries) are typically interpolated. That is, field observations at specific locations are used to project the fault trace (or geological contacts) between known points. These observations are typically supplemented with interpretations of other geoscience based datasets such as geophysics (e.g. aeromagnetic or gravity surveys) to refine interpreted location where there is no surface exposure. At a regional scale these boundaries are considered appropriate for delineating general aquifer boundaries and vulnerability districts. However, at a more local (e.g. property based scale) additional field work would typically be required to refine boundaries and relevant features such as fault location. 7) While wetlands and riparian zones along streams can at times be both recharge and discharge, for the purpose of this assignment they have all been considered discharge. It is understood that wetlands protection is being addressed by the Province as a separate management issue. 8) It was assumed that groundwater flow systems positioned between the QFF and the 200 m depth boundary for the Active GFS are all local or first order systems. Therefore, groundwater recharges over topographic highs and discharges in the adjacent lowland. It was assumed that the hinge line between recharge and discharge is approximately half way down the slope. This required assuming a homogenous isotropic system, which will be less accurate for the complexity inherent in the Mountain Flank Hydrological Region. This area was mapped by visually integrating the 5 m contour topographic layer from the 1:10,000 scale mapping with the drainage network from the regional 1:250,000 scale mapping on the GIS base. This approach was intended to be conservative, i.e. to maximize the potential extent of recharge zones. 9) Urbanized areas where storm sewers would divert any infiltrating precipitation were hoped to be removed, however no detailed mapping of same was available. This will likely be more appropriate to refinement at more localized and site specific areas. 10) Deep mining (i.e. potash mine) and hydrocarbon exploration and drilling could potentially alter recharge mechanisms by allowing vertical upward flow into the Active GFS from deep crustal scale flow systems. Since that pathway was not considered part of the definition of recharge for this assignment, the areas for these activities were not included within the scope of this study. 11) The nature of forest cover can exert a control on recharge directly by precipitation and/or indirectly through snowpack development and melt. However this relates more to the volume of recharge created, which was beyond the scope of this assignment. Therefore forest cover was not considered in assessment of recharge areas. 11

18 2.5 Task 5 Aquifer Vulnerability Assessment Vulnerability (for this study) was considered to be an intrinsic property of a groundwater system that depends on the sensitivity of that system to human and/or natural impacts. There may be more than one type of groundwater vulnerability (e.g. land use), therefore the term intrinsic (or natural) vulnerability was used to define it solely as a function of the natural system(s) hydrogeological factors. The conceptual model used for this study was the modified DRASTIC approach by Aller et al (1987). This model delineates vulnerability of the natural hydrogeological setting by assessing the following variables. D depth of water R net recharge A aquifer media S soil media T topography (slope) I impact of the vadose zone media C conductivity (hydraulic) of the aquifer D-depth to water: This determines the depth of material through which a contaminant must travel before reaching the aquifer and it may help to determine the contact time with the surrounding media. In general there is a greater chance for attenuation to occur as the depth to water increases because deeper water levels imply longer travel times. R net recharge: This represents the amount of water per unit area of land which penetrates the ground surface and reaches the water table. Recharging water therefore is a principal vehicle for leaching and transporting contaminants to the water table. The greater the recharge, the greater the potential for groundwater pollution. A Aquifer media: This refers to the type of consolidated or unconsolidated material which serves as an aquifer. An aquifer can be defined as a subsurface rock unit which will yield sufficient quantities of water for use. The type of aquifer material determines the route and path length of groundwater flow which a contaminant must follow. The path length is an important control in determining the time available for natural attenuation processes to occur and influence the amount of effective surface area which the contaminant may come in contact with and be adsorbed (removed) from solution. S soil media: This variable refers to that upper most portion of the unsaturated zone above the water table characterized by significant biological activity. The presence of fine-textured materials such as silts and clays can decrease transport of contaminants to depth. Moreover where the soil is fairly thick the attenuation process may be quite significant. T topography: This refers to the slope and slope variability of the land surface. It controls the likelihood that a pollutant will run off or remain on the surface long enough to infiltrate I impact of vadose zone media: The vadose zone refers to the zone above the water table which is unsaturated. The type of material found within the zone determines the attenuation characteristics for naturally purifying any contaminants that may start to be transported down toward the water table. The media also controls the path length and routing of water movement, thus affecting the time available for attenuation to occur. 12

19 C Conductivity (hydraulic) of the aquifer: This refers to the ability of the aquifer to transmit water, which in turn controls the rate at which groundwater will flow. This then controls the rate at which a contaminant moves away from the point at which it enters the aquifer. This concept of groundwater vulnerability is based on the assumption that the physical environment may provide some degree of protection to groundwater against natural and human impacts. This approach is used as a screening tool and not as a site assessment methodology. It helps to identify areas which are more or less vulnerable than others to contamination so that resources can be directed to those more vulnerable areas to help with management problems, thereby making the most of limited resources. It does not include consideration of salt water intrusion from the sea as a means of contamination. The assumptions made in this approach include: a pollutant having the mobility of water; a pollutant introduced at ground surface (therefore not subsurface burial); a pollutant carried towards groundwater by recharge from precipitation; and evaluated on areas exceeding 100 acres. Given the dominance of fractured HUs and the presence and importance of faults, DRASTIC was modified as per Denny et al (2007) to incorporate structural characteristics. Large scale fault and fracture zones can exercise a dominant control on the hydrogeology and by acting as conduits for groundwater flow at the regional and local scale. Adaptation of the methodology to fractured and structural zones is typically denoted Drastic-Fm to reflect that in fractured bedrock aquifers groundwater flow is predominantly through fractures, with large-scale fracture zones and faults acting as primary conduits for flow at the regional scale. This methodology has been applied to the southern Gulf Islands region of southwestern British Columbia, Canada wherein bedrock geology maps, soil maps, structural measurements, mapped lineaments, water-well information and topographic data, assembled within a comprehensive GIS database, formed the basis for assigning traditional DRASTIC indices, while adding the structural indices necessary for capturing the importance of regional structural elements in recharge and well capture zone determinations Higher DRASTIC scores indicate that the site is located in a generally sensitive or vulnerable area with numbers ranging from 65 to 223. Generally, the higher the DRASTIC index, the greater the pollution potential. The index provides only a relative evaluation tool and is not designed to provide absolute answers. This DRASTIC ranking system was applied to the recharge areas within each of the Hydrological Districts to assess regional vulnerability. 2.6 Ground-truthing This study was based on available mapping, and did not include ground-truthing. Extension and application of the study to site specific and local scale, and integration into a property based land use management system if desired in the future will require prioritizing of areas, and ground-truthing of results. 13

20 2.7 A Living Model, Assumptions and Limitations As noted by the Expert Panel on Groundwater (2009), Canada now clearly recognizes the need for source water protection as the first barrier in protecting drinking water quality. More generally the landuse planning process must consider the long-term availability and vulnerability of local groundwater resources and the potential for cumulative impacts. The products of hydrogeological studies, including aquifer mapping, characterization and modeling can serve as effective tools in integrating groundwater concerns into land-use management processes and policies, provided that the groundwater investigation precedes the land use development. Unfortunately no such regional hydrogeological studies have been carried out in the study area, so there are definite assumptions inherent in the mapping and therefore limitations to use of the data as summarized below. As the Panel noted: Models don t make decisions, people do. When used appropriately groundwater models can be useful tools to assist in making decisions in support of sustainable groundwater management. However, both the input and the output from a model must be subject to analysis before a final decision is made. In regard to an assessment of model uncertainty exp s overall approach to this assignment is best described by LeGrand et al (2000) where: The focus is on using generalizations and inferences with existing information to draw conclusions from imprecise and incomplete information. It is not equation based, but instead a rule-based system of inferences. The objective is to obtain optimal value from existing information no matter how meager, within imprecise but reasonable bounds. This approach highlights the minimal information available, the need to draw from experiences in other areas, the absence of ground-truthing to determine the accuracy of the mapping, and other factors such as role of climate change not being assessed at this time. Groundwater studies can occur at many scales, ranging from site-specific to regional; therefore, it was necessary to establish for the purpose of this regional study the appropriate scale for sustainable management and to tailor the science to that scale. Therefore, as per the Request For Proposal (RFP) and discussion with RDPC this assignment has focused on delineating recharge areas on a regional scale. Mapping produced for this study has drawn from a variety of scales of mapping resolution ranging from 1:10,000 to 1:500,000. Therefore the base of compilation for the maps shown in this report has been at a resolution of 1:100,000. It should be understood that while these recharge areas are important, it is does not necessarily preclude development. To create development guidelines there needs to be a move from this regional analysis to acquiring pertinent information at the property scale, as well as a prioritization of recharge areas to institute limitations on what can be done and how it can be done but not to curtail all development. In this regard the user of the data must remember that this approach and supporting database is not intended to replace, but instead to provide a framework for on-site investigations. 14

21 It should also be recognized that the boundaries for this assignment were politically based (i.e. land use planning jurisdictional based), rather than physically (watershed) based. As seen on Figure 1.1, several of the watersheds in the RDPC jurisdiction extend outside its boundaries. As a result there may be important recharge areas that lie within the watershed boundaries but that are outside the RDPC land management boundaries. The boundary lines shown to delineate Regions and Districts are approximate and should be regarded as diffuse zones, rather than defined lines; nor as barriers to flow. In addition, the vulnerability map provided with this report is designed for general usage only. It shows the sensitivity of groundwater to contamination in a generalized way; local details have been generalized to fit the map scale. The map does not show areas that have been or will be contaminated, or areas that cannot be contaminated, and given its regional nature the map should not be used for general application on a site-specific (e.g. PID specific) basis. Detailed studies of individual areas may be necessary when specific information is needed. Characteristics of individual contaminants and of the likelihood of contaminant release have not been taken into account when constructing the map. The conceptual models of groundwater settings, recharge areas and vulnerability should not be expected to provide unequivocal answers to issues in groundwater management. Rather, they provide simulated results that must be further considered in the context of providing practical solutions to the problem at hand. It is therefore imperative that model output uncertainties outlined above be carefully understood. As a consequence of uncertainty, the results of this study and the related conceptual models developed need to be viewed not as a one-time effort, but as an ongoing process. As additional field data are collected the model needs to be periodically adjusted and recalibrated, referred to as a living model, which is well suited to an adaptive management philosophy. 15

22 Chapter 3 Description of Study Area 16

23 3 Description of Study Area The subject area is located between the Bay of Fundy to Grand Lake and from Anagance to the Saint John River in New Brunswick. The property is currently the site of five villages and twenty-one local service districts, which are understood to have a combined population of 33,000. It is understood that the the RDPC jurisdiction was established in 1998 when the government passed the Royal District Planning Order, and is 608,634 hectares in area. In a general sense, the study area can be differentiated into three landscape types (Landscape Map of New Brunswick NR-9, 2003), as shown in Figure 3.1: the Caledonian Highlands (pink), the Highland Foothills (green), and the New Brunswick Lowlands (light green). 3.1 Geology The Caledonian Highlands region is located in the south of the RDPC district, and along the Bay of Fundy. This region is considered an old landscape as it is a remnant of an older mountain-forming episode, at which time it went through several cycles of uplift and erosion. Subsequently, it was modified by glaciations. Rocks in this region range in age from Cambrian to Silurian. The Highland Foothills region is located north of the Caledonian Highlands region. The landscape of this region was modified by glacial and melt-water processes and is characterized by moderate reliefs, sand and gravel deposits (e.g. eskers) melt water channels and drumlinized and fluted landforms. Flood plains are common and are normally wide and filled with sand and gravel and organic deposits. Within the subject property boundary, the New Brunswick Lowlands region is located north of the Highland Foothills region. The landscape of this region can generally be described as low-lying and undulating. Locally, the highest points are approximately 200 m. Abundant melt-water channels, wide flood plains, peat bogs and wetlands are all characteristic of this region (Landscape Map of New Brunswick NR-9, 2003). The generalized bedrock and surficial lithologies for the study area are represented on Figure A1 and Figure A2, respectively (Appendix A). 3.2 Topography Figure A3 (Appendix A) shows the topography of the study area. Along the coast, the topography of the Caledonia Highlands region ranges from flat wetlands to high cliffs and overall lies below 100 m in elevation. Moving inland from the coastline, the topography is dominated by a plateau of hills and mountains intersected with numerous river-lined gorges, which average about 300 m in elevation. North of the Highlands, the Highland Foothills region presents a dramatic topography of steep river valleys and rugged hills and mountains. Generally, crests can reach above 200 m with ridges typically rising to 150 m. In the New Brunswick Lowlands area the relief generally does not surpass 60 m and peak elevations go up to 160 m only. Rivers, bogs and other wetlands dominate the Lowlands landscape (NBDNR, 2007). 17

24 3.3 Climate The climate of the study area can be seen in Figure A4 (Appendix A). The high elevations and moderating influence of the Bay of Fundy are major factors contributing to the cool and wet climate of the Caledonia Highlands region. The moisture-laden air coming from the Bay of Fundy is intercepted by the high elevations contributing to the coastal area s high annual precipitation. Frequent winter storms and persistent fog are also characteristic of this region. The cold waters of the Bay moderate the local temperatures resulting in comparatively mild winters and cool summers. The climate in the Foothills region is relatively dry and warm and becomes warmer as distance from the Bay of Fundy increases. Generally, the New Brunswick Lowlands are protected from the moisture of the prevailing westerly winds and the precipitation from south westerly storms coming across the Bay of Fundy by the Highlands. The Lowlands surrounding Grand Lake are considered a hotspot with regards to climate. This area boasts the longest growing seasons and the warmest summer temperatures in New Brunswick (NBDNR, 2007). 18

25 19 Royal District Planning Commission

26 Chapter 4 Results 20

27 4 Results 4.1 RDPC Consultation Consultations with the RDPC were completed during the progress of the study. Representatives of exp met with RDPC members to discuss key aspects and objectives of the aquifer vulnerability project. Some of the key comments provided during the meetings included: There is concern regarding the potential degradation of the freshwater aquifers within the RDPC. Particular areas of immediate concern included Trout Creek and the Kingston Peninsula. It was agreed, however, that case studies were outside the scope of this regional study. Data availability for the area of interest was addressed. The definitions of an aquifer and of recharge for the purposes of this study were discussed. It was agreed that the effects of climate change would not be included at this stage of the study. Potential risks to aquifers were discussed and it was agreed that no particular one should be singled out and that this aspect of the study would not be addressed at this time. 4.2 Hydrological Setting Hydrostratigraphic Units The bedrock geology and surficial geology represent the key data layers from which hydrostratigraphic units were derived. The hydrological regions and districts were interpreted from a combination of a Digital Elevation Model generated for the area, interpreted hydrostratigraphic units, and interpreted bedrock/surficial geological maps. Approximately 189 geological units are present in the 1:50,000 scale digital bedrock geologic and the provincial scale surficial geologic maps. These included 172 bedrock units and 17 surficial geologic units. Seven (7) bedrock hydrostratigraphic units and five (5) surficial hydrostratigraphic units were interpreted and established within the context of the study. A total of nine (9) hydrological districts within four (4) hydrological regions have been interpreted in the area. As noted earlier, based on the boundary file received from the RDPC, which excludes the municipalities of Sussex and Hampton, the study area covers approximately 608,634 hectares. However, this boundary file area was modified to include these municipalities and exclude all mapped waterbodies and watercourses, resulting in a total assumed study region land area of 582,022 hectares. This area served as the basis for all modeling operations of the area related calculations in the project. Given the lack of detailed hydrogeological testing of the bedrock and surficial units within the study area, their conversion to Hydrostratigraphic Units (HUs) was based principally on existing hydrogeological experience; work by Baechler et al, (in progress) in similar terrain for the Cape Breton Region, N.S.; and the Geological Survey of Canada (2005) Maritimes Groundwater Initiative assessment in the Moncton area. 21

28 A regional assessment of the study area identified twelve HUs (seven bedrock and five surficial). The bedrock HUs include: Triassic HU, Structural HU, Cumberland HU, Windsor and Mabou HU, Horton HU, Volcanic Metamorphic HU and Igneous Plutonic HU. The Surficial HUs include: Colluvial HU, Organic HU, Residuum HU, Sand and Gravel HU and Till HU. The characteristics of the dominant HUs for this assessment are summarized below. The bedrock HUs and the surficial HUs can be seen in Figure A5 (Appendix A) and Figure A6 (Appendix A), respectively Bedrock - Igneous Plutonic HU (I p HU) This HU is comprised primarily of granites, formerly injected into magma chambers (plutons) at depth, then subsequently cooled and moved to the surface through erosion and isostatic uplift. It presently underlies areas of higher topographic relief, due to its resistant nature. It covers approximately 6.2 % of the study area. On a regional scale this HU exhibits relatively low transmissivities expected in the approximate range 0.1 to 5 m 2 /d. This characterizes the pervasive jointing that forms the background permeability in the upper 200 m. Discrete fault zones can potentially overprint with higher transmissivities. Generally this HU is considered a low yield aquifer dominated by fracture flow, which at times can produce sufficient quantities for domestic usage Bedrock - Igneous Volcanic/Metamorphic HU (I vm HU) This unit comprises igneous rocks including volcanic (i.e. lava flows, pyroclastics), as well as surrounding country rocks metamorphosed by heat and pressure, that are associated with the intrusion of the granitic plutons. It is positioned adjacent to the plutons and given its erosion resistant nature it is also found at the higher elevations, covering 19.2 % of the study area. On a regional scale this HU exhibits relatively low transmissivity, however, due to the wide variety of rock types present, it is expected to exhibit greater variability in transmissivity ranging from 0.1 to 50 m 2 /d. Again this characterizes the pervasive jointing that forms the background permeability within approximately the top 200 m; discrete zones of higher transmissivity can potentially be overprinted by localized fault zones. Generally this HU is considered a low yield aquifer, dominated by fracture flow, but at times can produce sufficient quantities for domestic usage Bedrock - Horton HU (H HU) As the mountains overlying the above two HUs eroded, the first sediment deposited now forms the sandstones and conglomerates of the Horton Group, covering some 6.0 % of the study area. Groundwater flow is predominately through fractures, but also within the rock mass, depending upon how well it has been cemented. On a regional scale this HU exhibits a relatively low to moderate transmissivity expected to range from 1 to 100 m 2 /d. Geological descriptions suggest higher permeabilities might characterize the zones adjacent the basin margin, due to more intense structure. In other areas this HU has been subdivided into two sub HUs, due to the presence of a low permeability argillaceous unit. However, no information is available to determine its presence in the study area. Generally this HU is considered a low to moderate yield aquifer, dominated by fracture flow, but can be expected to produce sufficient quantities for domestic usage. 22

29 Bedrock - Windsor/Mabou HU (W/M HU) Sediments of the Windsor and Mabou HU were deposited over the Horton as the basins became periodically flooded by the rise and fall of sea level. The sediments were deposited during five major cycles of sea water intrusion resulting in extensive evaporite deposits in certain zones. With the last recession the basin evolved into a river floodplain-lake environment in which fine grained muds and silt were deposited. In total this unit covers approximately 8.4 % of the study area. On a regional scale this HU exhibits highly variable transmissivity expected to range from 0.1 to 50 m 2 /d. Higher values can potentially be encountered within zones of karst. Generally this HU is considered a low yield and poor quality aquifer, dominated by fracture and karst flow, but at times can produce water of sufficient quantity and quality for domestic usage Bedrock - Cumberland HU (C HU) Following filling of the basins and retreat of the oceans another mountain building period occurred. The erosion of these mountains deposited a third package of sediment created by meandering/braided and reconnection of previously connected (anastomosed) river systems. This resulted in a sedimentary rock package including sandstone, siltstone and shales of the Cumberland HU, covering some 40.6 % of the study area. In some cases it has been possible to subdivide this unit into two sub HU s; however there is insufficient geological information in the study area to indicate whether such exists. Flow is predominately fracture controlled. On a regional scale this HU exhibits moderate transmissivities expected to range from 10 to 500 m 2 /d. Generally this HU is considered a moderate to high yield aquifer, dominated by fracture flow Bedrock - Structural HU (S HU) This HU comprises the zones where massive folding and faulting of the bedrock has occurred, which are kilometres in scale. The forces which created these zones were responsible for widespread fracturing in the other bedrock HUs, which give them their background permeability. However, this HU focuses on the epicentre of the tectonic activity where there may have been sufficient change to warrant a special designation, covering some 18.2 % of the study area. No intensive studies have been undertaken on this HU. Baechler (2009) suggests many are hydraulically active, which may be a function of progressive exhumation where deeply buried fault zones are gradually brought to the surface Based on previous work in similar terrain, transmissivities are expected to be in the range of 100 to 500 m 2 /d. Generally this HU is considered a moderate to high yield aquifer where hydraulically active; dominated by fracture flow Surficial - Till HU (T HU) Ice sheets advanced and retreated over four times across the Maritimes within the last 1 million years. During advances a wide variety of unconsolidated deposits were left overlying the bedrock. Till is the most widespread of these deposits. The complexity in ice flow directions, topographic relief and type of underlying bedrock created wide variations in the type of till. Unfortunately, detailed till morphological assessments have not been mapped out within the study and so all the variability is combined in one HU, covering some 71.3 % of the study area. This HU is not usually a target for water supply. Its importance stems from the control it exerts on recharge and directing precipitation either into overland flow to streams or through infiltration into the groundwater table. Generally this unit on a regional context is thought to be characterized by an average hydraulic conductivity of 10-4 to 10-6 cm/sec, with more clayey rich tills being in the range of 10-5 to 10-7 cm/sec. 23

30 Surficial - Sand/Gravel HU (S/G HU) This HU encompasses localized deposits of sand and gravel, whether formed by recent active stream action or by historical glacial fluvial deposits formed during retreat of the last ice sheet. It covers some 4.8 % of the study area. On a regional scale this HU exhibits variable but generally high transmissivities expected to range from 10 to 500 m 2 /d. Generally this HU is considered a moderate to high yield aquifer, dominated by porous media flow Hydrological Regions and Districts The identification of Hydrological Regions and Districts follows the method developed by Baechler et al (2009). This resulted in outlining four Regions and nine Districts as shown on Figure A7 (Appendix A) and Figure A8 (Appendix A), respectively. Of the four Regions identified, the largest is the Lowland Region covering 44.3 % of the study area. The Highland Region covers some 25.2 % of the study area. The remainder includes the Mountain Flank Region at 24.3 % and the Foothills Region representing 6.1 % of the study area. Each Region and its respective Districts are discussed below Highland Region The Highland Region was subdivided into three Districts including Peneplain (14.3 % of the study area), Crest (6.9 % of the study area) and Gorge (4 % of the study area). Overall this Region is underlain by more erosion resistant, crystalline basement bedrock, creating the areas of highest relief. Since these form the core of the former Appalachian Mountains, large scale faults, granite batholiths and associated volcanics and metamorphics have become exposed, and are now becoming hydraulically active. Overall these represent a tectonically old, deep seated, not structurally active, mountain landscape. The surface is gently undulating, with well rounded relief and low slopes. The width of the remnants varies between and within, with the larger ones identified as Peneplain District and the narrower ones identified as the Crest District. In many areas the peneplain surface is dissected by relatively large, steep sided, V shaped stream valleys and ravines, identified as the Gorge District, trending northwest - southeast. The steep edges of the highland remnants leading to the lowlands have been incorporated within the Mountain Flank Region. The HUs of the Region are characterized by the relatively low permeable, fracture controlled, igneous plutonic (I P ) and igneous volcanic-metamorphic (I vm ) HUs. The Structural HU is present throughout this District, but whether it is hydraulically active is unknown. The terrain is bedrock controlled, which is exposed over large areas. It is overlain by a variety of thin to discontinuous, relatively permeable surficial units. These include Sandy Till and Residuum HUs. The three-d conceptual block models summarizing the arrangements of the various HUs that make up this setting are provided in Figure

31 Mountain Flank Region The Mountain Flank Region, which covers 24.3 % of the study area, is divided into two Districts including the Fault District (16.3 % of the study area) and the Evaporite District (8.1 % of the study area). Note that the Fault District is distinct from the Structural HU, i.e. the former corresponds to a distinct district that constitutes a portion of the Mountain Flank Region. The latter refers to a mapped fault with 500 m buffer to either side (mapped faults are typically present in all the individual regions/ districts). This Region forms the contact between the core of the former mountains and the adjacent sedimentary basins, thereby providing the transition between areas of high and low topographic relief. It therefore generally forms northeast-southwest trending linears on either side of the highland remnants. Distinctive features comprise sharp, high relief fault scarps, step transition slopes marked by bare rock and discontinuous colluvium, occasionally dissected by deep incised stream gorges. The higher relief areas are underlain by igneous and metamorphic HUs with thin discontinuous glacial overburden, abutting at times steeply dipping sedimentary rocks under the adjacent lowland plain covered with thick glacial tills. This is the most complex of all Regions with very little geological data. A large number of HUs comprise this region, including the I p, I vm, S, H, and W/M HUs, covered with a thin, possibly discontinuous overburden, comprising Till and Colluvium HUs. Therefore a wide variety of transmisivities are expected, with rapid changes both laterally and vertically. The three-d conceptual block models summarizing the arrangements of the various HUs that make up this setting are provided in Figure Foothills Region The Foothills Region covers some 6.1 %of the study area. It was difficult to delineate given the sparse data. It appears to occur primarily in the central portion of the study area between and adjacent the three Highland Region blocks. It is characterized by uplands as the topography rises gradually into the highlands. Distinctive features comprise heavily dissected plateaus with well rounded, bedrock controlled slopes at moderate elevations underlain by conglomerates and sandstones and covered with a continuous blanket of sandy glacial till Lowland Region The Lowland Region, which covers approximately 44.3 % of the study area, is divided into three Districts that include the Alluvial Valley District (5.5 % of the study area), the Sedimentary Plain District (35.9 % of the study area) and the Windsor District (2.9 % of the study area). This Region is positioned primarily within two areas. One is nestled between the three Highland Regions in the east-central portion of the study area and one over the northern third of the study area. Distinctive features generally consist of a low lying, gently undulating plain. It is underlain primarily by sedimentary bedrock comprised of sandstone siltstones, shales and evaporites with a relatively thick glacial overburden comprised primarily of tills. In localized areas sands and gravels infill incised bedrock valleys or blanket broad alluvial valleys. 25

32 Figure 4.1: Highland Hydrological Region 3-D Block Diagrams of Districts (after Baechler et al, in progress) 26

33 Figure 4.2: Mountain Flank Hydrological Region 3-D Block Diagrams of Districts (after Baechler et al, in progress) 27

34 Figure 4.3: Lowland Hydrological Region 3-D Block Diagrams of Districts (after Baechler et al, in progress) 28

35 The Windsor District combines primarily the Windsor/Mabou HU, including evaporite deposits. Due to their easily erodible nature they tend to be found in the lower elevations. Given the high solubility of evaporates, both active and non-active karst is common. Given the lack of detailed geological mapping it was difficult to delineate this District. The best representation is identified within the central lowland area tucked in between the three Highland Remnants. Given its fine grained nature, the overlying Till HU is expected to be finer grained. The Sedimentary Plain District comprises large areas of the Cumberland HU, overlain by a sandier till sheet. The Alluvial Valley District comprises the major alluvial valleys. As a result it includes a wide variety of underlying bedrock and Till HU. One of the characteristics of the District are localized, at times large, areas underlain by the Sand/Gravel HU. The three-d conceptual block models summarizing the arrangements of the various HUs that make up this setting are provided in Figures Recharge Areas Based upon the methodology outlined in Section 2.4 the total recharge area encompasses 306,343 ha ha. This is broken down by Region/District in Table 4-1. The Structural HU (fault zones) had the greatest recharge area (105,999 ha) and the Well Head Protection Area had the smallest recharge area (802 ha). Table 4 1: Recharge Zones by Region and District Recharge Type Region District Percent of Total Study Area Topographic Highlands Region Peneplain District 7.8 Crest District 3.1 Gorge District 0.8 Mountain Flank Region Evaporite and Fault District 5.5 Foothills Region Horton District 1.0 Lowland Region Windsor District 0.4 Sedimentary Plain District 12.2 Alluvial Valley District 3.8 Structural HU 18.2 Sand/Gravel 3.1 WHPA s Aquifer Vulnerability Assessment The major recharge zones identified above where assessed in terms of their vulnerability to contamination through the modified DRASTIC-Fm methodology outlined in Section 2.5. The rankings were then color coded using the GIS mapping base and are provided on Figure A9 (Appendix A). Given the constraints associated with the DRASTIC ranking, which allows for only a qualitative comparison 29

36 between numbers, no low, moderate or high ranking system was employed in the color coding; simply the range in increments of 10. Nonetheless, in a relative sense, the higher the DRASTIC index, the more vulnerable the area. It is important to note that only recharge areas are classified under the DRASTIC protocol; as such areas not classified as recharge based on the criteria used in this study are not color coded and appear as grey in the aquifer vulnerability map. The major assumptions used in developing the DRASTIC numbers and mapping their spatial extent included: 1) Overlap of Recharge Zones: Where overlap occurred between various recharge zones the highest vulnerability ranking was applied. 2) Recharge Amount: Given the areas humid maritime climate and relatively high rainfall the maximum net recharge ranking was employed for all recharge types. 3) Fault Controlled Recharge Zones (Structural HU): Since the major faults which have been defined are large scale systems, worst-case conditions were applied to the Fm drastic parameter in terms of orientation, length and frequency of fracturing within 500 m of the defined fault zone. The selection of a 500 m distance is somewhat subjective and was based in part upon field experience on Cape Breton Island. In terms of orientation the Fm parameter, which was initially applied to the British Columbia structural system, was reversed for the Appalachian mountain structural system. In the latter the northeast southwest trending faults have a higher probability of representing the extensional fault systems. Additional assumptions included an active hydraulic system with moderate to high hydraulic conductivity and no confining layer. 4) Sand/Gravel Controlled Recharge Zones: Given that this HU is the only water table aquifer for ranking and tends to be positioned in lowland areas with high probability of man-made influence, worst-case conditions were applied. This assumed large, extensive recharge zones with a high water table, low topographic relief and comprised of coarse grained sands/gravels, with no confining till layer. 5) Topographic controlled Recharge Zones: Since these covered wider areas than the above two recharge types they encompassed a range in settings, especially the Mountain Flank Region. Therefore a range of DRASTIC rankings were developed, then assigned a typical value to provide one DRASTIC ranking for mapping. Even though the possibility of smaller scale faults exist, especially within the Highland Region, no such features have been mapped out on existing geological maps and therefore the Fm parameter was not employed. 6) WHPA s: Given the absence of detailed information on the hydrologic settings of the various well head protection zones worst-case conditions were used to provide a maximum DRASTIC ranking of >200. The resultant rankings indicated that: 1) The most sensitive zones with the highest vulnerability rankings included the Structural HU (i.e. fault zones) at 223, followed closely by the Sand/Gravel zone at 212. WHPA s were considered to be within the same range. 2) The topographic recharge zones varied from 100 to 174. Within this range the Highland Peneplain (174), Crest (161) and the Lowland Alluvial Valley District (161) were more vulnerable. 3) Within the topographic recharge zones the variability in rankings is outlined in Table 4-2. The greatest variability in DRASTIC rankings were found within the Mountain Flank Region, as expected, given the wide variety of potential hydrological settings. 30

37 Table 4 2: Ranges of Drastic Rankings within Topographically Defined Recharge Zones Recharge Type Region District From-To Typical Topographic Highland Peneplain (DRASTIC rankings Crest given under Topographic exclude faults that may Gorge cut the individual districts rankings for faults Mountain Flank Evaporite and Fault which are present in Foothills Horton most districts are addressed within the Lowland Windsor Structural HU classification). Sedimentary Plain Alluvial Valley Structural HU 223 Sand/Gravel 212 WHPA s >200 The term typical does not refer to a statistical term ie. arithmetic mean value taken from range. Instead it applies experience derived from other areas to derive a value that is expected to be typical or more characteristic of this area. 31

38 Chapter 5 Summary and Recommendations 32

39 5 Summary and Recommendations 5.1 Summary A regional scale aquifer vulnerability study of the RDPC lands was completed. The work included consultation with RDPC members concerning overall objectives regarding protection of the potable groundwater resource within RDPC s jurisdiction, the preparation of digital mapping, the delineating of HUs and the combining of HUs to define Hydrological Settings (Regions and Districts). The major recharge zones identified where subsequently assessed in terms of their vulnerability to contamination through the modified DRASTIC-Fm methodology. The study area used in the analysis was defined by boundaries provided by the RDPC (608,637 hectares) less waterbodies and watercourses for a final area of 582,022 hectares. Within this area, a total of 189 geological units were identified from existing mapping by others. These included 172 bedrock units and 17 surficial geologic units. These were then condensed into 12 hydrostratigraphic units (HUs) which control groundwater flow. The HUs were then combined in different numbers, types and orientation as a type of building block to form four Hydrologic Regions and nine Districts. Of the four Regions identified, the largest is the Lowland Region covering 44.3 % of the RDPC jurisdiction. The Highland Region covers some 25.2 % of the study area. The remainder includes the Mountain Flank Region at 24.3 % and the Foothills Region 5.5 % of the study area.. The Highland Region was subdivided into three Districts including Peneplain (14.3 % of the study area), Crest (6.9 % of the study area) and Gorge (4 % of the study area). The Highland Region is characterized by the relatively low permeable, fracture controlled, crystalline bedrock. Faults are present throughout this District, but whether they are hydraulically active is unknown. The Mountain Flank Region, which covers 24.3 % of the study area, is divided into two Districts including the Fault District (16.3 % of the study area) and the Evaporite District (8.1 % of the study area). This is the most complex of all Regions with very little geological data. A large number of bedrock HUs comprise this region covered with a thin, possibly discontinuous overburden. Therefore a wide variety of permeabilities are expected. The Foothills Region covers 6 %of the study area. It was difficult to delineate given the sparse data. It appears to occur primarily in the central portion of the study area between and adjacent the three Highland Region blocks. The Lowland Region, which covers approximately 44.3 % of the study area, is divided into three Districts that include the Alluvial Valley District (5.5 % of the study area), the Sedimentary Plain District (35.9 %) and the Windsor District (2.9 %). The HUs in this region encompass a wide variety of sedimentary bedrock and evaporites covered with an overburden represented by Till and Sand/Gravel HUs. Therefore a wide variety of permeabilities are expected. 33

40 The total recharge area encompasses 306,343 ha of the study area. The Structural HU had the greatest recharge area (105,999 ha) and the Well Head Protection Area had the smallest recharge area (802 ha). The major recharge zones identified were assessed in terms of their vulnerability to contamination through the modified DRASTIC-Fm methodology. The resulting index was found to range from a low (less vulnerable) index of 100 to a high of 223 (more vulnerable). The most sensitive zones with the highest vulnerability rankings included the Fault Zone at 223, followed closely by the Sand/Gravel zone at 212. Wellhead Protection Areas (WHPA s) were considered to be within the same range. The topographic recharge zones varied from 100 to 174. Within this range the Highland Peneplain (174), Crest (161) and the Lowland Alluvial Valley District (161) were more vulnerable. The greatest variability in DRASTIC rankings were within the Mountain Flank Region, as expected, given the wide variety of potential hydrological settings. It is important to note that there are definite assumptions inherent in the regional scale mapping produced for this study and therefore limitations to use of the data; for example direct application to more local scale. The conceptual models of groundwater settings, recharge areas and vulnerability should not be expected to provide unequivocal answers to issues in groundwater management. Rather, they provide simulated results that must be further considered in the context of providing practical solutions to the problem at hand. It is therefore imperative that model assumptions and output uncertainties outlined within this report be carefully understood. As a consequence of uncertainty, modeling needs to be viewed not as a one-time effort, but as an ongoing process. As additional field data are collected the model needs to be periodically adjusted and recalibrated, referred to as a living model, which is well suited to an adaptive management philosophy. 5.2 Recommendations Should RDPC wish to proceed with further work, it is recommended that the results of the regional aquifer vulnerability assessment be used as the basis to prioritize and refine aquifer vulnerability for site specific areas, and strategies be developed to integrate results of aquifer vulnerability into RDPC s land use planning water resource education initiatives and objectives. 34

41 Chapter 6 Acknowledgments 35

42 6 Acknowledgements Exp wishes to acknowledge the input of the Royal District Planning Commission members, and the various organizations including the New Brunswick Department of Natural Resources whose products and services contributed significantly to study objectives. 36

43 Chapter 7 References 37

44 7 References Aller, L., T. Bennett, J. Lehr, R. Petty and G. Hackett, 1987, DRASTIC: A standardized system for evaluating Groundwater Pollution Potential using Hydrogeologic Settings, EPA-600/ , 455 pages. Expert Panel on Groundwater (2009), Denny, S.C., D.M. Allen, and J.M. Journeay, 2007, DRASTIC Fm: A modified vulnerability mapping method for structurally controlled aquifers in the southern Gulf Islands, British Columbia, Canada. Hydrogeology Journal 15: Baechler F., L. Baechler, N. Bach and D. MacNeil, in progress, Cape Breton s Waterscape, the Blue Jewel of the East. LeGrand, H.E. and L. Rosen, 2000, Systematic Makings of early Stage Hydrogeologic Conceptual Models, Groundwater, Vol. 38, No 6, pp

45 Appendix A Figures Royal District Planning Commission

46 This map is meant only as a representation of the GIS based digital mapping product provided to RDPC. Use or reproduction of this material subject to permission of exp. Royal District Planning Commission

47 This map is meant only as a representation of the GIS based digital mapping product provided to RDPC. Use or reproduction of this material subject to permission of exp. Royal District Planning Commission

48 This map is meant only as a representation of the GIS based digital mapping product provided to RDPC. Use or reproduction of this material subject to permission of exp. Royal District Planning Commission

49 This map is meant only as a representation of the GIS based digital mapping product provided to RDPC. Use or reproduction of this material subject to permission of exp. Royal District Planning Commission

50 This map is meant only as a representation of the GIS based digital mapping product provided to RDPC. Use or reproduction of this material subject to permission of exp. Royal District Planning Commission

51 This map is meant only as a representation of the GIS based digital mapping product provided to RDPC. Use or reproduction of this material subject to permission of exp. Royal District Planning Commission

52 This map is meant only as a representation of the GIS based digital mapping product provided to RDPC. Use or reproduction of this material subject to permission of exp. Royal District Planning Commission

53 This map is meant only as a representation of the GIS based digital mapping product provided to RDPC. Use or reproduction of this material subject to permission of exp. Royal District Planning Commission

54 This map is meant only as a representation of the GIS based digital mapping product provided to RDPC. Use or reproduction of this material subject to permission of exp. Figure A9. Recharge Area and Aquifer DRASTIC Value