CHARLTON – Casella Waste Systems, operator of the Southbridge Recycling and Disposal Park, aims to identify the direction of groundwater in a nearby neighborhood of contaminated private wells by putting data-logging pressure transducers in seven residential wells, a spokesman for the company told the Board of Health on Tuesday. The Vermont-based waste management company wants to put the transducers in the wells of Charlton homes at 54, 81, 90, 102 H Foote Road, 9 and 19 Eleanor Lane, and 190 Berry Corner Road.