A Midwestern food production company retained Ayres to assist in rapidly developing a response and recovery plan and monitoring after the wintertime failure of an underground force main that transfers process wastewater from a food production facility to a pre-treatment pond. The failure of this force main resulted in the release of process wastewater into a drainage ditch and wetlands adjacent to a river.
Ayres first assisted with initial recovery efforts and evaluation of the extent of the release and its effect on the frozen wetlands. Surface water samples were collected along the drainage ditch and from locations in the wetland and were analyzed for biological oxygen demand (BOD), chemical oxygen demand (COD), nitrogen, chloride, phosphorous, and dissolved oxygen (DO).
During the initial evaluation of the release, it was discovered that wastewater-impacted surface water flowed west of the release site along a drainage ditch and north through two culverts running beneath railroad tracks. These culverts provided access points for the impacted water to flow into the adjacent wetlands.
During initial recovery efforts our team evaluated the effect of pumping wastewater-impacted surface water from the ditch near the culvert closest to the release point. The initial assessment indicated that pumping from this location would effectively pull some impacted surface water out of the wetlands north of the railroad tracks.
Based on these preliminary findings, Ayres recommended additional activities, including continued sampling and weekly inspections of the wetlands during the spring melting period and inspections within 24 hours after any spring rainfall event of 0.5 inches or greater, assessment of the observable condition of wetland soils and surface water, and installation of best management practices (BMPs) such as absorbent containment booms, sonde meters, solar-powered aerators and other devices to prevent the spread of adverse impacts, and continued monitoring of impacted surface water.