Coal Ash Cap started to erode and exposed the coal ash under the cap. Rainfall would carry the exposed coal ash downhill, into a creek, which then deposited into a major lake. A design build project was completed with two flumes, undersized riprap in the flumes, which resulted in a project failure at the first rainfall. D2 was contacted to create a site-specific solution and provide erosion control measures.
Initially, a temporary sediment control device called GeoRidge was utilized to mitigate the erosion and reduce the flow of contaminated water into the creek and lake. D2 aided in the design and identified the control measures and the appropriate products for the site.
The design of the project utilized grade control structures to decrease the speed of the water before it would hit the down slope flumes. Articulated concrete block mats in the high flow areas and turf reinforcement mats with native vegetation in the lower flow areas were incorporated in the down slope flumes. At the bottom of the hill, a landing pad of articulated concrete block was used and the water was diverted via a weir structure. A step down system was incorporated using GeoWeb, turf reinforcement mats and native vegetation. The stairstep portion of the project was constructed using gabion structures, below them baffles and settling ponds are used to clean the water prior to releasing it into normal flow situations.
D2 aided in the design, supplied the materials and assisted the contractor in construction of the project. The combination of design, products and on-site assistance lead to the resolution of the erosion issue and the elimination of contaminated water reaching important waterways.
- Articulated concrete block mats
- Turf reinforcement mats
- Native seeds