Battelle Memorial Institute
Burgess & Niple (B&N) was retained by Battelle Memorial Institute to investigate the condition of this local protection project and provide documentation to the Federal Emergency Management Agency (FEMA) in support of removal of this property from the 100-year-flood map. As part of this submittal, the main levee which extends approximately 1,100 feet along the Olentangy River, had to be analyzed. There were no construction records or maintenance records for this levee.
B&N developed and supervised a geotechnical investigation to obtain data necessary to evaluate the stability and seepage performance of the levee. Test borings were drilled along the crest of the levee and toe of the levee to define the levee and levee foundation soil conditions. Since the flood durations were such that steady-state seepage would not be anticipated, moving saturation lines were calculated using transient flow net methods, and used to define the phreatic surface in the slope stability analysis. A geotechnical report was prepared by B&N summarizing the investigation and the results of the stability analysis.
During review of existing Battelle facility drawings, B&N discovered that some of the parking lot storm sewers utilized large-diameter dry wells to divert stormwater into a sand and gravel stratum underlying the site. This sand and gravel stratum appeared to be the same layer which was encountered by the borings approximately 6 feet below the base of the levee and hydraulically connected to the river. Seepage out of these dry wells during flood flows was a concern. B&N performed a levee underseepage analysis to estimate the amount of seepage out of the dry wells into the plant parking area which would have to be controlled by the existing internal drainage pump station.