Midwest Refinery Project

 

 

Alma Refinery Project

From 1936 to 1999 Total Petroleum operated the former Alma, Michigan refinery. Over that time the process capacity reached a maximum of 52,000 barrels of oil per day and the refinery expanded to cover 180 acres. Losses of mostly refined hydrocarbons impacted soils and groundwater at the site. Natural groundwater flow caused two primary hydrocarbon plumes to migrate offsite. HMA personnel were initially involved with the facility in the 1990s to evaluate the extent and magnitude of these offsite plumes while the refinery remained in operation.

 

In 2003, the site owner entered into a Corrective Action Consent Order with the Michigan Department of Environmental Quality. Subsequently, HMA prepared the final RCRA Facility Assessment Report and the RCRA Facility Investigation Work Plan to address remaining onsite impacts to soil and groundwater. The RCRA Facility Investigation is scheduled for 2008 and 2009 to complete assessment activities onsite.

 

Geologically, the site overlies a thick mantle of unconsolidated glacial drift at least 400 feet thick. The glacial deposits are composed of multiple sequences of ground moraine (fine-grained hard diamicton) separated by recessional outwash (coarse-grained sands with gravel). The entire drift package is capped by a thin veneer of glacial lake sediments. Outwash deposits form channels, the bases of which locally cut through the underlying diamicton to form vertical hydraulic connections among the outwash units. These complex sandy deposits form the principal groundwater and contaminant transport pathways.

 

Extensive investigation was required to discern the complex hydrostratigraphic architecture of the drift. Monitoring wells installed at various locations in the drift revealed that horizontal groundwater flow directions varied by as much as 180 degrees depending on depth within the system. Initial interim measures were designed and implemented to control any further offsite migration and stabilize of flow within the deeper offsite outwash units.

 

Subsequent remedial efforts focused on returning the offsite groundwater back to its highest possible use. Groundwater quality within the offsite deeper outwash deposits was returned to useable quality in 2007 and meets Michigan drinking water standards.

 

Past offsite migration of phase separated hydrocarbons occurred along the water table surface in one plume area. Approximately 50,000 gallons of offsite free product were removed by the end of 2007 by means of skimming (15,000) and soil vapor extraction (35,000). Only traces remain and final polishing of the free product areas by means of air sparging will address remaining impacts at the water table.

 

In 2005 and 2006, once the facility decommissioning and demolition work was completed, a site-wide integrated storm water management system was constructed to work with the existing groundwater control systems for the onsite area of the former refinery. Storm water and treated groundwater can be directed to infiltration galleries at the upgradient edges of the facility to both enhance biologic remedial activity within the subsurface and help to sustain the subsurface water resource across the facility. The system allows excess storm water to be collected in retention basins and automatically released to the county storm system if necessary. During dry weather, a majority of the treated groundwater can be directed to the infiltration galleries.

 

Final corrective measures at the facility will rely on engineering controls and use restrictions to manage environmental risk. All stakeholders expect the site to undergo redevelopment in the future, possibly as the central hub of the proposed Alma Energy Park.