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Maryland Power Plants and the Environment (CEIR-18)

5.4.2 Restoration of Disturbed Lands

Beyond historic mining practices, other factors may disrupt natural landscapes and flow patterns. Karst geology and the sinkholes associated with it can cause land subsidence and can severely damage buildings and infrastructure. Quarry activities can create artificial sinks for ground water that alter the natural direction of ground water flow and can exacerbate the development of solution channels that may already be present. CCB grouts have been shown to have sufficiently high strength and low permeability to help mitigate these problems when properly engineered and injected.

The Hoyes Run Project provided an excellent example of this use (Figure 5-16). Hoyes Run is a highly valued trout stream adjacent to the Key Stone Quarry in Garrett County, Maryland. During periods of low flow, its entire flow was lost to solution channels developed in a loss zone near the Quarry. Initial attempts to seal the channels using a conventional chemical grout were unsuccessful because these grouts expanded with such pressure that partings in the streambed increased causing even greater stream loss. A grout of fly ash and fine particle FBC material was developed to effectively fill the solution channels and seal the streambed without causing any problems so long as the channel entrances could be identified and isolated for grout injection. The grout proved to be highly effective at sealing the small openings and channels in the limestone bedrock. However, during a period of high rainfall and high flow rate in the stream, clay layers overlying the limestone bedrock were washed out and new areas of stream loss developed. Thus the project demonstrated the strength of the CCB grout seals, but also called attention to the need for thorough study and understanding of site specific geology in planning restoration projects.

Figure 5-16 Hoyes Run Project

The image shows a man standing near a creek before restoration

Photo courtesy of WMGISC

Photo shows the stream after restoration

Photos During and Shortly After 2007 CCB-Grout Injection at Hoyes Run. Stream flow was restored within hours of grout injection.