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Kelso Quarry Park

From Quarry to Public Conservation Area, in Ontario’s Greenbelt

February 1, 2010  By Sarah Lowe BSc MSC & Sherry Yundt BA MA FIQ

The former Milton Limestone Quarry in the Town of Milton, Region of Halton, is on the edge of the province’s major population centre: the Greater Toronto Area.  The quarry opened in 1958 along with others in the local area to provide construction materials to build the new provincial Highway 401.

The former Milton Limestone Quarry in the Town of Milton, Region of Halton, is on the edge of the province’s major population centre: the Greater Toronto Area.  The quarry opened in 1958 along with others in the local area to provide construction materials to build the new provincial Highway 401.

Aerial photograph of the operating Milton Limestone Quarry in the 1980s.

The strategic location near Toronto has made the site an excellent one for supplying aggregates to Canada’s largest market.  It is situated on the physiographic feature known as the Milton Outlier on the Niagara Escarpment, which is an excellent source of high quality Silurian Amabel dolostone. The outlier had active quarries and lime kilns in the early 1900s. The quarry supplied one million tonnes per year of crushed stone for construction uses for over 40 years until operations ended in 2001.

Location of Kelso Quarry Park, a former quarry site within the Niagara Escarpment Plan Area and Ontario’s Greenbelt.
Final stages of quarry floor extraction create the future lake (2000).
Lake levels are controlled by a small weir (2003)
Lake levels are controlled by a small weir (2006)
The Ontario Stone, Sand & Gravel Association (OSSGA) awarded Barrick Gold the Outstanding Achievement in Property Rehabilitation Award for the final rehabilitation of the quarry site into the Kelso Quarry Park.
Aerial photo of Kelso Quarry Park and adjacent natural escarpment edge.
Hundreds of volunteers planted almost 4000 native trees, shrubs and wetland plants in the Kelso Quarry Park as part of Conservation Halton’s Trees for Watershed Health Program (2007).
Turkey vultures, a symbol of the Niagara Escarpment, gather in the rehabilitated quarry.


The strategic location of the site also makes the rehabilitated quarry a prime candidate for public use. Not only is it less than 50 km on provincial highways from downtown Toronto and Hamilton, it is situated in a scenic and rich natural area of the Niagara Escarpment. Over a thousand hectares nearby are already in public ownership, visited by thousands of residents and tourists each year for skiing, hiking, rock climbing, swimming, boating and outdoor education.

The site is in the Niagara Escarpment Plan Area, within the Province’s Greenbelt The Greenbelt is an area of over 700,000 hectares of green space that the province established in 2005 to preserve the natural resources from urban development. 

Lands adjacent to the site are owned by Conservation Halton, a local environmental agency that operates on a watershed basis. A major function of Conservation Authorities is protecting watersheds through ownership and management of lands, which are also used for public education and recreation. One of their public parks is the Kelso-Glen Eden Conservation Area, which is immediately next to the former quarry. This park includes a major ski area, extensive trails above the escarpment and a reservoir (Lake Kelso).  While the main function of the reservoir is for flood control and stream flow augmentation, it is also a major recreation facility for swimming and boating.

The active life as a fully working quarry was followed by a second stage of 10 years where the final rock was recovered during site rehabilitation. The quarry was donated to the Conservation Authority in August 2006.  In its new life as a public conservation and recreation area, it joins several other former quarries in the Region of Halton that contribute natural heritage and recreation values as public parks (Zimmerman and Lowe 2006).

A visionary public private partnership
When the quarry approached the end of its operating life in the mid 1990s, Conservation Halton recognized the potential value of the site as an addition to its existing Kelso-Glen Eden Conservation Area. They negotiated with the owner, Barrick Gold Corporation, to donate it when fully extracted and rehabilitated. Lands to be donated included the rehabilitated quarry and the adjacent 700 m swath of natural forest and cliffs that had been protected from extraction within the 71 hectare licensed area. 

The natural forest and cliffs are ecologically significant and will be protected in a Nature Reserve “Special” zone in the Master Plan to be completed by Conservation Halton. The University of Guelph’s Cliff Ecology Group discovered an old growth forest of eastern white cedar there in the mid 1990s, and the Nature Conservancy of Canada has expressed interest in helping to provide support to protect this ecosystem. 

An innovative part of the agreement between Conservation Halton and Barrick Gold was to refine the final rehabilitation plan to accommodate Conservation Halton’s wishes for a recreational lake, while remaining consistent with the requirements in the Site Plans approved under the Aggregate Resources Act.

Innovative design and award-winning rehabilitation
The quarry had been progressively rehabilitated from the 1970s, with the east cliffs sloped and planted with grasses and thousands of native trees. However, the main activity occurred in the past 10 years, as the limits of the property were reached. The approved rehabilitation plan included a 5-metre deep lake in part of the quarry floor and identified recreation as a possible after-use.

The rehabilitation was particularly innovative in the approach to cliff and slope creation to produce varied landforms, and the configuration of the lake in the quarry floor to make it suitable for a public recreation area.

Initially, the quarry faces were backfilled conventionally from top to bottom in 2:1 and 3:1 slopes as per legislation, using native soil and imported clean fill. These slopes provide linkage to the abutting natural areas. However, when more recent extraction was complete along the last (west) face along the unopened Sixth Line road allowance (Bell School Line), a different approach was used. The quarry face was to be left as a cliff rather than back-filled.

An attempt was made in the late 1990s to perform a “restoration blast” where the blast action itself produces the final rehabilitated landform. The aim was to establish a ledge that could be revegetated half way down the 25 – 30 m high face. Unfortunately, although the blast was carefully designed and executed, it was not totally successful. The shot rock did not clear the ledge and left an unstable surface of loose rock that had to be scaled. However, for aesthetic purposes, the upper cliff face was left exposed at the top with only the bottom two thirds backfilled. The resulting cliffs are compatible with the surrounding natural cliff landscape and are accepted by the regulating agencies as a valid form of rehabilitation in this scenic location.

A detailed rehabilitation plan designed by staff at Conservation Halton guided the final extraction of the quarry floor. The lower few metres of the excellent Amabel Formation and some of the underlying Reynales Formation were extracted to recover the last remaining bedrock resource and create the final lake configuration (Figure 3).  The lake design included shallow areas and shoals for fish habitat, and also areas for future public beaches. Lake levels were determined as part of a hydrogeological study. Levels are managed by a small weir structure, allowing gravity outflow for the spring freshet or storm water events into a defined open channel, which then flows through a buried drainage channel that eventually surfaces at the edge of the escarpment.

Instrumental in carrying out the rehabilitation plan was the Quarry Manager, Bill Scott, who took on the additional task of a much more elaborate rehabilitation program than normal. Bill passed away in 2006.  In addition to carrying out the company’s and Conservation Halton’s directions, he also provided his own personal touch to the quarry rehabilitation, including the placement of large boulders beside the lake.

Over the years, the company used several grass and legume mixtures to stabilize the slopes and quarry floor, and planted native trees on the slopes.  A list of the grass mixtures and trees planted is included in Table 1. As a result of the outstanding success of the final rehabilitation, the Ontario Stone, Sand and Gravel Association (OSSGA) awarded Barrick Gold the prestigious Outstanding Achievement in Property Rehabilitation Award in 2007.

Already a public asset 
Today, the former quarry site is an exceptionally beautiful property set within the surrounding natural area of the escarpment and Conservation Halton has trails that run along the western edge of the property. These trails also connect to the Bruce Trail, which is an 845 km public hiking trail that runs along the Niagara Escarpment from Niagara Falls to Tobermory. The property itself is not yet open to the public.

Since taking ownership in 2006, Conservation Halton has completed soils and groundwater site remediation around the former workshop area and has also carried out tree planting as part of its Trees for Watershed Health Program. Wildlife is already beginning to use the rehabilitated areas of the quarry.

The role of the quarry site as part of the Kelso-Glen Eden Conservation Area will be further evaluated as the 2002 Kelso Masterplan and the Niagara Escarpment Plan are updated. This review will include biological inventories of the property so that land use designations can allow for active public use, as well as protect the valuable natural ecosystem along the edge of the escarpment. Conservation Halton views the Kelso Quarry Park as an excellent example of rehabilitation and plans to implement the installation of park infrastructure and facilities befitting this spectacular regional escarpment park.

This article was first published in Canadian Reclamation (published on behalf of the Canadian Land Reclamation Association [CLRA/ACRSD]). Reprinted with permission of the CLRA/ACRSD and Aquila Publishing. The authors thank staff at Conservation Halton for their assistance with this article.

Conservation Halton. 2007… Halton Hikes 50 Great Hiking Trails.
Conservation Halton. 2002. Master plan.
Conservation Halton. 2008. Viewpoint Quarry Expansion and Rehabilitation.
S.E. Yundt Limited Outstanding Achievement in Property Rehabilitation Award. APAO Milton Limestone 2004.
Zimmerman, K. and S. Lowe. 2006. Rehabilitated Quarries provide a public asset in the Greenbelt. NEC Leading Edge Conference 2006.

 1. Ministry of Transportation (MTO) standard Roadside groundcover mix (slopes):
    55% Creeping Red Fescue
    27% Kentucky Blue Grass
    15% Perennial Rye Grass
    3% White Clover.

2. MTO Mixture with “Crown Vetch” added (west slope, hydroseeded).

3. Park Mixture an “all-purpose” specification (other areas):
    40% Kentucky Blue Grass
    40% Creeping Red Fescue
    20% Annual Rye Grass

white ash  
white birch  
black cherry   
white elm   
black maple  
striped maple   
bur oak       
white pine   
slender willow   
gray dogwood   
Saskatoon berry   
red osier dogwood    

trembling aspen white cedar
choke cherry
shagbark hickory
silver maple
sugar maple
red oak
white spruce
prairie rose
pussy willow   
highbush cranberry

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