Ground Water Extraction Projects:
Framework for a Hydrogeologic Study in support of an Application for an Environmental Assessment Certificate under the Environmental Assessment Act and Regulations
1. General Information
Ground water extraction may be a project in of itself (for example for municipal water supplies) or a component of other major projects such as pulp and paper mills, mining projects, fish hatcheries, resorts. Where ground water extraction is being proposed from one or more wells at a combined rate of 75 litres or more per second, the Environmental Assessment Office should be contacted with regard to the reviewability of the project under the Environmental Assessment Act (refer to the Reviewable Projects Regulation, Part 5, Table 9, number 4). The following guidelines serve as reference to the types of hydrogeological information that should be included in an application for an Environmental Assessment Certificate with respect to the ground water component of the project. These guidelines are useful for projects that are reviewable under the Environmental Assessment Act as a ground water project or for other reviewable projects that have a significant ground water extraction component.
The Water Protection Act affirms the province's ownership of the ground water resource and restricts the bulk export of ground water. The Fish Protection Act enables the designation of water management areas and development of plans where there are risks to water quality including ground water. British Columbia has no ground water management legislation or regulations requiring permits or regulating activities such as well drilling and ground water use. The Province has published Guidelines for Minimum Standards in Water Well Construction, 1982, and the Draft Code of Practice for Construction, Testing, Maintenance, Alteration and Closure of Wells, 1994. The province is progressively developing an integrated approach to ground water management including non-regulatory measures, such as enhanced inventory of wells and guidelines for community well protection. Communities dependent upon ground water are encouraged to consider and incorporate measures to protect ground water within their community planning activities.
The purpose of a hydrogeologic (ground water) study, as part of an Environmental Assessment Application, for a proposed ground water extraction project or resource development project is:
- to identify the extent, use and potential of the ground water resource in and around the proposed development,
- to define and assess the potential impacts of the proposed development on the ground water resource and its users including fisheries habitat needs,
- to outline mitigative and monitoring measures to ensure that the integrity of the ground water resource in its present condition is maintained for present and future use.
The following guidelines have been prepared to assist development proponents in British Columbia in addressing site specific ground water concerns in their environmental impact assessment reports. It is recommended the hydrogeologic study be conducted by a person registered as a Member of the Association of Professional Engineers and Geoscientists of British Columbia with competency in the field of hydrogeology. Retaining a consulting ground water professional to design, supervise and report on the development of the ground water supply from start to finish will ensure potential environmental impacts are identified and that adequate well construction and testing procedures are followed.
3. Potential Impacts
The hydrogeologic report should include information consistent with investigation of the following potential impacts, where applicable:
Reductions in streamflow and surface water availability including effects on low flow regimes, lakes and springs, fully recorded streams and fisheries habitat in particular spawning beds.
Interception of ground water flow critical for maintenance of forest and grasslands habitat, wetlands and fisheries habitat in particular spawning beds.
Interference with licensed water users.
Interference with existing wells. For example, reduced capacity of domestic wells.
Sea water intrusion in coastal areas resulting in water quality degradation impacts on other users including shellfish beds and fish habitat.
Non-sustainable extraction or aquifer mining where extraction exceeds replenishment reducing water availability for all users of the aquifer.
Land stability and subsidence, including but not limited to development of sinkholes.
Property damage, flooding or siltation caused by uncontrolled flowing artesian wells.
Impacts of an increase in extraction rate.
Impacts upon existing agriculture and silviculture activities.
Impacts on water availability for land in the Agricultural Land Reserve that currently is not irrigated or does not have a water supply.
The report should identify the recharge area of the source aquifers (including discussion of past, present and planned land use in the area over the area of recharge), the capture zone of the well, any well protection measures, as well as identify measures to be taken to mitigate any significant potential ground water resource degradation including use of interceptor wells or grout curtains. The report should identify and discuss potential impacts of development on the ground water resource quantity and quality and interrelated surface water resource, and assess the significance of these impacts in terms of human, wildlife and fisheries habitat needs.
4. Steps To Take in the Environmental Assessment Process
Depending upon project specifics such investigations may be expected to contain:
4.1 Inventory and Analysis of Available Information including:
- published geology and hydrogeology reports;
- soils maps;
- geology maps;
- watershed maps;
- aquifer classification maps;
- aerial photography;
- climatic data;
- water well record data;
- exploration test holes and test pits;
- observation well data;
- pumping test data;
- geophysical data;
- ground water chemistry data;
- surface water data
4.2 Site Investigations
Field investigations of the site and analyses of hydrogeologic data, including:
- a location survey and identification of water wells, test pits, piezometers , exploration test holes , and surface water courses in and around the proposed development area;
- locations and measurements of discharges of any springs discharging from the source aquifer;
- identification of surface water courses and measurement of their discharges, evaluation of annual and long term (>10 year) precipitation patterns within the aquifer recharge zone;
- measurements of ground water levels in water wells identified within the aquifer impact area and in piezometers and test holes within the proposed development area;
- chemical sampling of ground water (the individual parameters to be tested depend on the type of proposed development and the nature of potential contaminants),
- conducting short term (up to 6 hours) and long term (greater than 24 hours) pumping tests and/or permeability tests;
- conducting geophysical surveys (e.g. seismic, EM);
- conducting test hole drilling;
- installing piezometers and automatic water level monitoring equipment;
- digging test pits for soil identification and shallow ground water table conditions;
- collecting lithologic data from test holes, test pits, piezometers and monitoring wells.
4.3 Environmental Assessment Application and Report including the following elements:
4.3.1 Results of Investigation and Analysis
These are to be presented in a hydrogeologic report outlining results of office and site investigations and analyses of data including but not limited to the following:
- purpose of the ground water extraction project;
- general description of the geographic setting, landforms, topography, drainage, climate, soil types, geomorphologic conditions;
- general description of geologic setting; type and nature of geologic materials; vertical and lateral extent of individual geologic units; stratigraphy and structural features;
- locations and descriptions of aquifers (confined, unconfined, unconsolidated, bedrock); aerial extent and thickness; aquifer properties (transmissivity, etc.);
- evaluation of the water balance, including precipitation / snow melt, evapotranspiration, infiltration and runoff conditions;
- assessment of aquifer budget, including amount and source(s) of recharge; quantity of ground water in aquifer storage; current amount of ground water extraction; amount of ground water discharge; potential amount available for future ground water extraction;
- description of local and regional ground water flow systems and rates of movement;
- evaluation of ambient ground water level trends;
- evaluation of surface water / ground water interaction, including quantity and quality;
- evaluation of pumping test data from existing test or production wells, including both long term (minimum 24-hour) pumping and recovery test data, and analysis of long term (minimum 100 days) safe yielding capacity of these wells. (For water diversion wells general guidelines regarding well testing procedures which should be considered are presented in Appendix 9 of the Ministry of Environment, Lands and Parks' (now Ministry of Environment) publication: Water Utilities - Guide to Applying for a Certificate of Public Convenience and Necessity (CPCN), 1998.;
- evaluation of drawdown interference effects of test/production well pumping on neighbouring wells, springs, licensed surface water users, low flow surface water conditions, agriculture and silviculture activities, and ground water flows critical for the maintenance of forest and grassland habitat, wetland fisheries habitat and spawning beds;
- evaluation of ambient ground water quality conditions;
- evaluation of the vulnerability of the aquifer(s) to contamination,
- evaluation of development impact on potential land instability, subsidence, sinkholes;
- if applicable, an assessment of potential property damage, flooding or siltation caused by uncontrolled flowing artesian wells;
- numerical models of the ground water regime and extractions;
- an assessment of the impacts of future increases in extraction rate from production wells;
- evaluation of present and potential ground water use, including the quantity and quality of ground water to be used for the development and how and where it is to be disposed.
4.3.2 Hydrogeologic Maps and Cross-sections
For the project area, and for a distance from the project area that would depend on the character of potential impacts, hydrogeologic maps and cross-sections should be provided outlining the extent of unconfined/confined unconsolidated aquifers and bedrock formations; locations of water wells, exploration holes, piezometers, springs, test pits; (potentiometric) water level contours; water quality contours (e.g. nitrates, salinity); directions and rates of ground water flows and locations of surface water courses.
4.3.3 Potential Impacts
Identification and general assessment of the potential impacts of development on the quantity and quality of the ground water resource and any interrelated surface water resources, including specific details on the types and characteristics of potential contaminants and their sources. Some development projects may require inclusion of potential effects from open pit and/or underground mining development, dewatering, tailings storage facilities, waste rock dumps, ore stockpiles, or settling ponds.
Details of purpose, locations and design of monitoring wells and/or piezometers in relation to any potential sources of ground water contamination or potential low flow surface water impacts. The number of wells or piezometers required to effectively monitor ground water quality needs to be identified, including the identification of what specific subsurface zones are being monitored, frequency and type of data collection (i.e. water levels, water quality). Include field sampling methods, methods of reporting and analyzing data, as well as, field and laboratory sample quality assurance and quality control procedures.
Identification of mitigative measures to avoid or minimize any significant short and long term ground water quality degradation or quantity effects, particularly on any nearby domestic ground water users and any alteration of fish habitat.
4.3.6 Well Protection Plan
Plans for developing and implementing a Well Protection Plan, including a contingency and emergency response plan. Refer to the fact sheet "Well Protection Planning for Community Wells in British Columbia", (Reference 6).
The Well Protection Toolkit (Reference 7) is a set of guidelines for the six-step approach on how a community or water purveyor can develop and put into place a Well Protection Plan to protect well water supplies and prevent contamination. The Toolkit contains seven booklets which discusses the six steps needed to develop a Well Protection Plan and includes an example of how each step is implemented in the fictitious community of Pumphandle, B.C.
4.3.7 Well Closure
Well closure should be carried out in accordance with the provisions of Draft Code of Practice for Construction, Testing, Maintenance, Alteration and Closure of Wells, Province of British Columbia, 1994.
5. Reference Documents
1. B.C. Environment, 1998. Water Utilities - Guide to Applying for a Certificate of Public Convenience and Necessity (CPCN).
2. Ministry of Health, Public Health Protection Branch. Guidelines for the Approval of Waterworks (B.C. Regulation 230.92 - Safe Drinking Water Regulation).
3. Kreye, R., M. Wei, and D. Reksten, 1995. Defining the source area of water supply springs. Hydrology Branch, B.C. Environment.
4. B.C. Environment, 1982. Guidelines for Minimum Standards in Water Well Construction, Province of British Columbia. Ground Water Section, Water Management Branch, 35 pp.
5. B.C. Environment, October 1994. Draft Code of Practice for Construction, Testing, Maintenance, Alteration and Closure of Wells, Province of British Columbia. Ground Water Section, Water Management Branch.
6. B.C. Environment, June 1996. Well Protection Planning for Community Wells in British Columbia. Ground Water Section, Water Management Branch.
7. B.C. Environment, B.C. Ministry of Health, May 1999. Well Protection Toolkit . Province of British Columbia. Ground Water Section, Water Management Branch. ISBN 0-7726-4165-X.