The purpose of the Big Walnut Augmentation/Rickenbacker Interceptor (BWARI) sewer project was to increase the capacity of the existing wastewater collection system. This project benefited central Ohio by improving the water quality of the area streams and rivers by reducing plant bypasses and sewer overflows and by providing additional capacity to the Columbus wastewater collection system.
Over 20,000 ft. of 14 ft. diameter precast concrete segment tunnel was constructed via earth pressure balance tunnel boring machine (EPBTBM). The tunnel was excavated through highly permeable glacial tills that a high ground water table. In addition, 7 shafts were constructed by drilling with bentonite slurry due to the high ground water table.