NEW CASTLE COUNTY WASTEWATER DISPOSAL SITE EVALUATION - SOUTHERN SEWER SERVICE AREA
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New Castle County was in the process of expanding wastewater services to its Southern Sewer Service Area (SSSA). Being considered as part of the service plan was the approximately 900 acre Water Farm No. 2 project site, which consisted primarily of active farmland, located just north of Middletown, Delaware.

Duffield Associates was part of a project team evaluating the suitability of rapid infiltration basins (RIBS) and spray irrigation for wastewater disposal at the Water Farm No. 2 site, as well as identifying and evaluating additional sites within the SSSA for potential land-based disposal of effluent.

Duffield Associates' role in the project included performance of a two-phase field investigation, designed to establish a hydrogeologic framework for the site and provide data necessary to perform a detailed groundwater impact analysis. The investigations included the performance of test borings and the installation, development, slug testing and pump testing of groundwater monitoring wells. The data obtained was utilized to develop the site-specific hydrogeologic framework that would be incorporated into future evaluations. Future evaluations recommended consisted of working with the Delaware Department of Natural Resources and Environmental Control, as well as the Delaware Geological Survey, to conduct deep aquifer (pump) testing, construction of a large scale test basin to evaluate hydraulics for groundwater mounding and fate and transport of chemical constituents, and developing a 3D groundwater flow model to make predictions with regards to the potential impacts of the wastewater disposal facility on local groundwater quality and sensitive receptors such as streams and potable supply wells.