Wildcat Brook Shale Pit Remediation and Wetland Expansion Project

Reason for Remediation

Wildcat Brook is part of the Petite Rivière watershed, which is situated just outside of the town of Bridgewater near the community of Wilville (see map). Monthly water quality sampling conducted by Coastal Action within the brook has revealed high acidity. This high acidity is likely caused by bedrock geology of the area. In particularly, there are old abandoned shale pit site that had been previously excavated for construction purposes over 20 years ago. When pyritic shale is exposed to water and the atmosphere it will chemically react to create sulfuric acid.

Rainwater collects and pools in the excavated pits. The water that is collected in these static pools can chemically react with the geology creating acidic water averaging low fours on the pH scale (similar to the pH orange juice), which then can overflow into the nearby Wildcat Brook during heavy rainfall events. These acidic shocks to Wildcat Brook can be detrimental to aquatic life. Wildcat Brook is a tributary to Hebb Lake, one of the three lakes that provide habitat for the globally endangered Atlantic Whitefish (Coregonus hunsmani), and also provides the drinking reservoir for the town of Bridgewater. Acidification of aquatic habitats is being recognized as one of the threats to the recovery of the Atlantic Whitefish, and it also impacts other aquatic species such as trout and salmon.

 

The Plan

Coastal Action teams up with land reclamation experts, East Coast Aquatics (ECA) to develop a plan to restore the old abandoned shale pit sites. There are several open shale pit sites in the area, but for the moment Coastal Action plans to focus on the smallest of them, a site approximately 1 ha in area. During the period the pit was active the top soil was removed exposing the bedrock. This left the area almost completely open and barren of vegetation. The plan is to transform this area into a wetland by replacing the open and barren landscape with organic soils and adding vegetation.

Coastal Action and ECA are currently seeking for soils that might be suitable for this type of restoration. The best type of soils are those coming from wetlands that are being excavated for other purposes. This aquatic soils are great because they already have root cuttings and are seeded with vegetation. Compost is also another great source of soil for barren areas surrounding the pit to encourage vegetation growth. If you know of any available soil sources please do not hesitate to contact Coastal Action.

The efforts of remediation project will be monitored throughout and after the project by water quality sampling, invertebrate sampling, periodic electro-fishing in the area, and monitoring the growth of vegetation of the area.

It is the hope that this expansion of the wetland will not only reduce the amount of acidity running into Wildcat Brook, but also provide a natural habitat to many wildlife species both terrestrial and aquatic.

 

Wildcat Shale Pit Sounding Area 2

PR-WC-Flooding

PR-Shale Pit 2

The top figure shows the location of the shale pit remediation site and Wildcat Brook. The middle photo illustrates a staff member standing in Wildcat Brook after a heavy rainfall event. Water level would normally be just above a person's ankles in this brook and is up to this staff member’s waist after a heavy rainfall event. The bottom photo illustrates one of the static pools within the abandoned shale pit that could possibly overflow into the brook. The overflow of these pools into the brook can cause acidic shocks to the system, which can be detrimental to most aquatic life.