
SERVICESHydrogeology
Hydrogeology
Our hydrogeology group is hands-down, the most approachable and practical group of hydrogeologists that you will ever meet (not that you are likely to meet a lot of hydrogeologists). GEMS specializes in the groundwater flow studies (physical hydrogeology) that are needed for land development projects, dewatering control during construction, permits to take water and discharge agreements in the City of Toronto and surrounding areas.
We work closely with geotechnical engineers and project managers to identify constructability issues related to groundwater, obtain necessary permits, approvals and authorizations, and liaise with stakeholders and other interest groups on your behalf. Integrating a practical, action-based approach to hydrogeological studies, our advice is down-to-earth and works on construction sites.



Baseline Receiver Water Quality
Before starting a land development or construction project that is going to influence a surface water feature review agencies often insist on documenting pre-construction baseline water quality conditions. They do this so they can confirm that the project doesn’t have a long-term effect on the groundwater system.
GEMS specialize in the technical studies and regulations related to managing environmental issues during construction, including Baseline Receiver Water Quality Assessments. We can undertake a complete baseline report of the groundwater conditions at site, including water quality, water levels and flow direction for your project.
Dewatering Feasibility
Construction dewatering and groundwater control is the removal or lowering of the water table at a site to allow for subsurface construction activities like excavation for sewer and water, foundations, shoring.
A dewatering investigation is a hydrogeological study that characterizes the subsurface conditions and evaluates the properties of soil and rock materials to inform dewatering operations.
A dewatering investigation will determine the site specific hydraulic conductivity of the soil and rock at the site by response testing or pump testing groundwater monitoring wells. This information allows an experienced hydrogeologist to forecast the zone of influence of dewatering and if the pumping will interfere with any water supplies or natural features and if taking water will lead to any settlement issue at neighboring buildings.
GEMS can review and evaluate the feasibility of dewatering your project site and make recommendations to the appropriate type of dewatering system.
Dewatering Investigations
Construction dewatering and groundwater control is the removal or lowering of the water table at a site to allow for subsurface construction activities like excavation for sewer and water, foundations, shoring.
A dewatering investigation is a hydrogeological study that characterizes the subsurface conditions and evaluates the properties of soil and rock materials to inform dewatering operations.
A dewatering investigation will determine the site specific hydraulic conductivity of the soil and rock at the site by response testing or pump testing groundwater monitoring wells. This information allows an experienced hydrogeologist to forecast the zone of influence of dewatering and if the pumping will interfere with any water supplies or natural features and if taking water will lead to any settlement issue at neighboring buildings.
GEMS hydrogeologists specialize in the technical studies and regulations related to managing groundwater and related issues during construction, including Dewatering Investigations. We can undertake a dewatering investigation for you project to forecast how much water you will need to pump.
Dewatering Plan Review
Construction dewatering and groundwater control is the removal or lowering of the water table at a site to allow for subsurface construction activities like excavation for sewer and water, foundations, shoring.
A dewatering investigation is a hydrogeological study that characterizes the subsurface conditions and evaluates the properties of soil and rock materials to inform dewatering operations.
A dewatering investigation will determine the site specific hydraulic conductivity of the soil and rock at the site by response testing or pump testing groundwater monitoring wells. This information allows an experienced hydrogeologist to forecast the zone of influence of dewatering and if the pumping will interfere with any water supplies or natural features and if taking water will lead to any settlement issue at neighboring buildings.
GEMS can review your proposed dewatering plan to make sure it meets the requirements for submission as part of the discharge application.
Discharge Permits (including Toronto Water Short- and Long-Term Discharge Agreements)
Sewer Discharge Permits and Agreements are required when private water (water not purchased from the City) is discharged into the City’s sewer system, including storm sewers, sanitary sewers or combined sewers. The City of Toronto’s Sewers Bylaw requires a Sewer Discharge Permit and/or Agreement be obtained and executed before any private water discharge can occur. Examples of private water include: groundwater, surface water, construction dewatering, rainwater (mixed with construction material), and stormwater (mixed with construction material)
GEMS hydrogeologists have the experience and relationships to secure your discharge permits. We can l prepare and submit formal applications for short- and long-term (permanent) authorization to discharge.
Environmental Activity Sector Registry (EASR)
EASR is an online self-registration system implemented by the Ontario Ministry of Environment, Conservation and Parks. People engaging in activities prescribed in “EASR regulations” must register those activities in the EASR. As of March 29, 2016, water takings (road construction and construction site dewatering) that meet the criteria in O. Reg. 63/16 must be registered in the EASR.
If the water takings are prescribed by regulation for the purposes of the EASR (road construction and construction site dewatering), a PTTW is not required.
Instead, the activity must be registered in the EASR by filing information related to eligibility criteria described in O. Reg. 63/16. The registered water taking must continue to meet the criteria set out in the regulation and the water taker must comply with the operational requirements set out in the regulation including obtaining the required water taking plan and discharge plan where applicable.
GEMS qualified hydrogeologists meet the criteria set out in regulations and can complete Hydrogeological Studies and prepare the Hydrogeological Studies needed for Permit to Take Water (PTTW) or Environmental Activity and Sector Registry (EASR) application.
GEMS can also prepare and apply to register an EASR with the Ministry of Environment, Conservation and Parks (MECP), to allow for dewatering during construction.
Environmental Compliance Approvals (s.53 OWRA)
The Ontario Ministry of Environment, Conservation and Parks regulates releases of substances to air, land or water through a permit called Environmental Compliance Approval (ECA). They used to be called Certificates of Approval (CofA). ECA’s are regulated under the Ontario Environmental Protection Act.
GEMS specializes in the technical studies and regulations related to managing groundwater and related issues during construction including discharges regulated under section 53 of the Ontario Water Resources Act. We can work with your project team to do anything from giving advice based on our experience, to doing the technical work, all the way up to handling the whole permitting process for you.
Groundwater Baseline Report
Before starting a land development or construction project where groundwater is going to be pumped, either for dewatering during excavation or earth works review agencies often insist on documenting pre-construction baseline groundwater conditions at your site and surrounding area. They do this so they can confirm that the project doesn’t have a long-term effect on the groundwater system.
GEMS hydrogeologists specialize in the technical studies and regulations related to managing groundwater and related issues during construction, including Groundwater Baseline Reports. We can undertake a complete baseline report of the groundwater conditions at site, including water quality, water levels and flow direction for your project.
Groundwater Under the Direct Influence of Surface Water Assessment (GUDI Study)
A GUDI study is a hydrogeological study to support a water supply in areas close to significant surface water features. The study focuses on the potential for drawing surface water into the water supply through pumping. This is critically important when designing treatment for the water supply.
GEMS experienced hydrogeologists are QPs and can complete GUDI Studies and reports to support your land development project.
Hydrogeological Assessment Submissions
Review agencies, like the City, Region and Conservation Authority usually require a report summarizing a hydrogeologic assessment of the proposed development in support of Land Development Applications.
These Hydrogeologic Assessment Submissions have be prepared by Qualified Persons (QPs). A QP is a licensed Professional Geoscientist or an exempted Professional Engineer as set out in the Professional Geoscientists Act of Ontario.
GEMS experienced hydrogeologists are QPs and can complete Hydrogeological Assessments in support of land development projects to satisfy review agency requirements.
Hydrogeological Characterization
Review agencies, like the City, Region and Conservation Authority may require a report characterizing the hydrogeologic conditions of a proposed land development or construction Project.
Hydrogeologic characterizations should be prepared by Qualified Persons (QPs). A QP is a licensed Professional Geoscientist or an exempted Professional Engineer as set out in the Professional Geoscientists Act of Ontario.
GEMS experienced hydrogeologists are QPs and can complete Hydrogeological Characterization to support your land development or construction to satisfy review agency requirements.
Hydrogeological Study Reports – Environmental Activity Sector Registry (EASR)
EASR is an online self-registration system implemented by the Ontario Ministry of Environment, Conservation and Parks. People engaging in activities prescribed in “EASR regulations” must register those activities in the EASR. As of March 29, 2016, water takings (road construction and construction site dewatering) that meet the criteria in O. Reg. 63/16 must be registered in the EASR.
If the water takings are prescribed by regulation for the purposes of the EASR (road construction and construction site dewatering), a PTTW is not required.
Instead, the activity must be registered in the EASR by filing information related to eligibility criteria described in O. Reg. 63/16. The registered water taking must continue to meet the criteria set out in the regulation and the water taker must comply with the operational requirements set out in the regulation including obtaining the required water taking plan and discharge plan where applicable.
GEMS qualified hydrogeologists meet the criteria set out in regulations and can complete Hydrogeological Studies and prepare the Hydrogeological Studies needed for Permit to Take Water (PTTW) or Environmental Activity and Sector Registry (EASR) application.
Hydrogeological Study Reports – Permit to Take Water (PTTW)
Ontario Ministry of the Environment, Conservation and Parks use a risk-based approach to managing water takings across the Province. Applications for water taking that is considered high risk related to interfering with existing users or natural function of ecosystems are Category 3 Water Takings.
Category 3 water takings need to be supported by a hydrogeological study that evaluates the potential for unacceptable impacts to occur as a result of the taking.
Hydrogeological studies must be prepared by a Qualified Person (QP). A QP is a licensed Professional Geoscientist or exempted Professional Engineer as set out in the Professional Geoscientists Act of Ontario. The QP must sign and stamp a completed report which is submitted to the ministry and shall take professional responsibility for its content and the accuracy of the information contained therein.
GEMS experienced hydrogeologists are QPs and can complete Hydrogeological Studies and prepare and stamp Hydrogeological Study Reports in Category 3 Permit to Take Water (PTTW) or Environmental Activity and Sector Registry (EASR) application.
Permit to Take Water (PTTW)
Ontario Ministry of the Environment, Conservation and Parks use a risk-based approach to managing water takings across the Province. Applications for water taking that is considered high risk related to interfering with existing users or natural function of ecosystems are Category 3 Water Takings.
Category 3 water takings need to be supported by a hydrogeological study that evaluates the potential for unacceptable impacts to occur as a result of the taking.
Hydrogeological studies must be prepared by a Qualified Person (QP). A QP is a licensed Professional Geoscientist or exempted Professional Engineer as set out in the Professional Geoscientists Act of Ontario. The QP must sign and stamp a completed report which is submitted to the ministry and shall take professional responsibility for its content and the accuracy of the information contained therein.
GEMS experienced hydrogeologists are QPs and can complete Hydrogeological Studies and prepare and stamp Hydrogeological Study Reports in Category 3 Permit to Take Water (PTTW) or Environmental Activity and Sector Registry (EASR) application.
GEMS can also prepare and apply to register a PTTW with the Ministry of Environment, Conservation and Parks (MECP), to allow for dewatering during construction and/or long-term water taking on your behalf
Permits and Approvals
Managing groundwater during construction is becoming more, not less complicated. With multiple review agencies, from the City to the Ministry of the Environment and Conservation Authority, that regulate water taking and water discharge during and after construction, you need to work with an expert in managing groundwater for land development and construction projects. GEMS specializes in environmental issues for construction.
GEMS hydrogeologists specialize in the technical studies and regulations related to managing groundwater and related issues during construction. We can work with your project team to do anything from giving advice based on our experience, to doing the technical work, all the way up to handling the whole permitting process for you.
Toronto Water Hydrological Review
The City of Toronto community planners requires a Hydrogeological Review to support applications for Zoning By-Law Amendments, Plans of Subdivision, Consent to Sever and Site Plan Control.
A Hydrological Review is a third party review of the technical groundwater information related to managing groundwater quality and quantity related to planning applications.
GEMS hydrogeologists are qualified to complete this review.
Water Balance
Review agencies, like the City, Region and Conservation Authority are concerned about how land development and construction projects will influence the natural system. Review agencies will ask for a water budget or water balance to understand and forecast how a project will influence the surface water / groundwater system.
GEMS experienced team of hydrogeologists and surface water specialists can complete pre- and post-construction water balances to satisfy review agency requirements.