Introduction

The Maryland Port Administration (MPA) is examining the possibility of raising the dikes at the existing Cox Creek DMCF and/or expanding the facility onto adjacent MPA-owned upland areas. Previous subsurface geology and groundwater investigations for the existing facility were conducted by the US Army Corps of Engineers, Baltimore District, in the late 1990’s as part of the Baltimore Harbor Anchorages and Channels, Maryland, Integrated Feasibility Report and Environmental Impact Statement. Since that time water supply and usage in northern Anne Arundel County and southern Baltimore City and Baltimore County have changed. Obtaining additional information on the subsurface geology and obtaining groundwater-level data from the proposed expanded area is recommended, given the changing pumping conditions and the time elapsed since the situation was previously evaluated.

Objectives

The objective of this study is to obtain additional subsurface geologic data from the existing monitoring wells at and near the Cox Creek site and to measure water levels in those wells. Additional data will be collected in wells F-1, F-2, E1, C-1, and D-2 referenced in Baltimore Harbor Anchorages and Channels, Maryland, Integrated Feasibility Report and Environmental Impact Statement- Appendix J dated March 1997 and shown in Figure 1. The additional data should consist of:

Geophysical logs: Because of the variability of the geology in the Potomac Group sediments which underlie the site, mapping the hydrogeologic units using lithologic logs alone is difficult. Only the lithologic logs were used in the previous Corps of Engineer’s study. To better characterize the Potomac Group sediments at the site, geophysical logs will be obtained from existing wells.

Groundwater-level measurements: Because of the time elapsed since the Corps of Engineer’s study, and the changes in groundwater usage in the region, water levels in the existing monitoring wells will be measured in order to map the groundwater potentiometric surface of the Lower Patapsco aquifer. Water levels will be measured once in all the monitoring wells in order to construct a potentiometric surface map. In addition, pressure transducers will be installed in two wells for approximately one month to identify local, temporal fluctuations in groundwater levels.

PROJECT DESCRIPTION

The Maryland Geological Survey (MGS) will refine the hydrogeologic framework at the Cox Creek site and its relations to the regional framework. MGS will also determine the head gradient and direction of groundwater flow in the Lower Patapsco aquifer in the vicinity of the Cox Creek site and its relation to the regional potentiometric surface.

Hydyrogeologic Framework

MGS will determine the hydrogeologic units present beneath the Cox Creek site through inspection of the geophysical logs and existing lithologic logs. MGS will also prepare structure maps and cross sections.

Head Gradient Determination

MGS will collect approximately one month of continuous water-level record in two existing monitoring wells and one-time water-level measurements in the remaining monitoring wells.