American Electric Power retained Burgess & Niple (B&N) to review facility permitting and permit compliance for an underground coal mine and preparation plant near Cadiz, Ohio. B&N consolidated NPDES and air permits for the Cadiz Mine Portal and Nelms Preparation Plant facilities and made improvements to their wastewater handling operations.
After evaluating the Cadiz Mine Portal facility, B&N recommended improvements to the stormwater collection/settling pond and the sanitary wastewater treatment system. The settling pond, which receives runoff from the coal pile storage area and underground mining operations, was not consistently meeting the NPDES discharge permit limits for suspended solids. Recommendations included a new baffled outlet structure to retain floating solids and eliminate pond short-circuiting.
Stormwater and wastewater at the Nelms Preparation Plant included runoff from coal storage facilities, leachate from an on-site mining waste landfill and coal wash water. Water from these sources was directed to settling ponds with a manually controlled sodium hydroxide feed for metals precipitation and solids removal.
B&N improved NPDES permit compliance at Nelms with the design of an automated pH adjustment system and baffled primary settling pond to help meet fluctuating hydraulic conditions. The primary settling pond includes an initial pH adjustment basin with floating mixers to improve pH control, followed by a series of deep settling ponds for solids collection. A bypass pipeline was installed around the initial settling ponds for periodic solids removal.