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Township of Wellington North Groundwater Management Study

Executive Summary

Burnside Environmental (Burnside) was retained by the Township of Wellington North to undertake a groundwater management study under the Ministry of the Environment (MOE) Provincial Water Protection Funding (PWPF) program assistance. The MOE provided funding assistance to a number of municipalities in Ontario under the PWPF whose principal objectives included the following:

• to obtain better understanding of the groundwater resources,
• to assess potential sources of contamination, and
• to assist in the development of groundwater protection strategies.

The principal expectation of the MOE, common to all municipalities, is the development of a consistent groundwater resource database including water wells, geological and hydrogeological information, potential contaminant sources etc to help identify groundwater issues and initiate development of groundwater protection strategies. This study is the first effort by the Township of Wellington North in developing a comprehensive, regional scale, understanding of the groundwater conditions in the area.

Database Development

Geological, hydrogeological and water resources data was collected from various government sources. Since this study was intended to raise public awareness, a resident water well survey was sent to rural residents. Approximately 24 percent of residents participated in the survey which was designed to obtain significant levels of domestic water well and septic system information.

The MOE water well record database provided the principal basis for most of the hydrogeological mapping and interpretation completed in the present groundwater management study. The MOE water well record database for the Township of Wellington North was not fully updated. In the Township 261 wells out of a total of 806 wells needed to be verified in the field for their location and well details.

Databases in MS ACCESS compatible format were established in this study for the resident well/septic system surveys, hydrogeologic reports and potential contaminant sources and streambed monitoring. A Site FX database was set up for the water well records and monitor wells as required by the MOE. As the Township of Wellington North is acquiring GIS capability, these databases developed in the study can be easily imported to the Township's GIS system for future use and analysis.

Field Work

Four new monitoring wells were installed as part of the project. One each centrally located in Arthur and Mount Forest, a shallow well near Well 5 in Mount Forest and a 150 mm test well in Arthur. The well in Arthur was tested at 15.2 L/s (200 Igpm). This deep aquifer is now considered to be the best prospect for a needed new municipal well in Arthur.

Ten, multi level streambed piezometers were installed at selected locations to monitor stream flows and to assess surface water/groundwater interactions. Significant effort was required for the Mount Forest deep bedrock multi-level monitor well which was completed to a depth of 165 metres.

Each municipal well in Mount Forest and Arthur was variable rate tested to determine their existing capacities.

Geology

The bedrock underlying the Township of Wellington North consists of shale, dolomite, and limestone. Bedrock formations consisting of Amabel dolomite located in the east contain the best bedrock aquifers in the area. The Salina Formation located west of Arthur and Mount Forest produces wells of equal capacity but harder water quality with typically more iron. The vast majority (over 80%) of wells in Wellington North are completed in the bedrock aquifer.

The overburden in the Township consists of glacial formations and include occasional granular deposits. Elongated surficial granular deposits are present in the centre of the Township as is found at the landfill site in Riverstown. Deep, well protected confined overburden aquifer formations are present south of Arthur and possibly along the western boundary with Minto west of Mount Forest.

Groundwater flow generally emanates from a high area just west of the Luther Marsh. In general, the groundwater flow reflects the topography which slopes to the west with smaller components to the south (in West Luther) and to the north along the northern Township boundary with the Township of Southgate.

Groundwater Use and Water Quality

The Township of Wellington North, has a population of 10,432 (in 1996) of which 55% live in Arthur and Mount Forest which are serviced by Municipal wells. The residents in rural areas are serviced by individual wells. In general, it was determined that water use accounts for only a small percentage of the total estimated deep groundwater infiltration within the Township of Wellington North.

Vertical Gradients and Groundwater Recharge/Discharge

Vertical hydraulic gradients were generally found to be downward at most monitoring locations which typically correspond with elevated portions of the study area. Based on the surficial geology, most of the area within the Township is covered by low permeability till deposits. As such, recharge occurs at a low rate over a large area.

Upward hydraulic gradients are interpreted along the Conestoga and Saugeen Rivers and the low lying streams that flow into them. These areas of potential discharge represent far less area than the recharge areas.

Groundwater Modelling

The groundwater flow simulations were achieved using the relatively simplistic, two dimensional semi-analytical United States Environmental Protection Agency Well Head Protection Area (WHPA) model. As the initial level of data for the Township was relatively limited, this approach was considered appropriate and cost effective.

The capture zones provide an indication of the area of influence of the municipal wells. The capture zone for the bedrock wells in Arthur are nearly circular areas around Wells 2 and 3 while an elongated capture area for Well 7 site obtains groundwater flow from the east. The Mount Forest capture areas are elongated to the east. Possible sources of contamination were identified in the capture areas. The mapped capture areas need to be calibrated using more detailed numerical modelling combined with pumping tests prior to designation of well head protection areas.

Potential Contaminant Sources Inventory

Potential sources of contamination were identified by reviewing records on file with various agencies. Records on file with the Technical Standards and Safety Authority (TSSA), the Insurer's Advisory Organization (IAO), and the MOE were reviewed for information regarding fuel storage, hazardous waste generators, PCB storage facilities, landfill sites, contaminated sites (spills, incidents, illegal dumping) and cemeteries. Some of the main findings are summarized below:

Table ES-1: Summary of Potential Contaminant Sources Inventory

Potential Source of Contamination	Number of Sites	Data Source
Fuel Storage Tanks	75	Combined total
	27	TSSA (22 diesel, 62 gasoline, 8 Propane and 6 "other" tanks)
	14	IAO Records and Plans
	30	Known Sites (some overlap with TSSA dataset data source: Township of Wellington North)
Waste Disposal Sites	4	MOE files
Contaminated Sites	14	MOE Files (some overlap exists with other datasets eg waste disposal sites)
PCB Storage Sites	1	MOE database
Waste Generator Database Generators: Generators Manifesting Waste in 1998: Waste Receivers and Carriers:	46 11 3 Receivers 3 Carriers	MOE database
Organic Soil Conditioning Sites	41	MOE files
Septage Sites	0	MOE files

Although the majority of aquifers in Wellington North are protected by fine grained overburden, careful management of possible contaminant sources is required to prevent long term impacts.

Review of Groundwater Management Strategies

Groundwater management strategies represent tools that can be used by municipalities to regulate and encourage specific land use activities to promote groundwater protection. The Wellington County Official Plan currently states that "Groundwater needs to be protected as it is an essential resource for urban and rural water supplies". Specific reference to land use in and around the capture areas for the municipal wells of Arthur and Mount Forest during future Official Plan amendments should be considered. In this report, a brief review of the current Provincial regulatory framework and the current official plan have been completed. A discussion on possible measures that can be taken to protect the groundwater is also included. It is recommended that review of zoning changes and site plan reviews include a site specific hydrogeologic investigation to evaluate the proposed land use changes to preserve groundwater quality.

It is important to note that the Ministry of the Environment is currently evaluating the requirements for a well head protection regulation which would significantly assist municipalities in planning to protect their wells.

Conclusions

The groundwater resource assessment and the inventory and mapping of potential contaminant sources provides the Township of Wellington North with understanding of the source of water for both rural domestic and municipal wells. By combining preliminary capture zone areas, an understanding of the types of domestic wells, geology with the possible sources of contamination the Township of Wellington North can begin to manage its valuable groundwater resources. These resources are capable of providing a relatively well protected potable source of water to the residents of Wellington North on a long term basis.

This study is the first stage of a successful groundwater protection strategy. A detailed program of further work is outlined in Section 9.