ABSTRACT
The Palmyra area has a long history of subsidence related problems. From October 1991 to October 1993 the Borough of Palmyra spent an estimated $900,000 in repair costs for eight sinkholes. Six out of the eight sinkholes had previous repair records going back to the mid-1960’s. Sinkhole activity was so routine that residents began calling Palmyra “the sinkhole capital of Pennsylvania.”
The subsidence problems are linked to an ineffective storm water management program. Stormwater is directed to areas outside the borough boundary via swales, limited piped outlets, or overland flow. The discharge points for the storm water often coincides with historically active sinkhole locations. Existing sinkholes within the Borough are also used as storm-water drains. At times these types of drains were frequently overwhelmed causing backup, localized flooding, and flushing out of nearby karst drains. The use of storm-water basins as an alternative has been met with local opposition. The argument is that the basins and the land area adjacent to the basins would be the focus for additional subsidence.
Solutions to the problem are compounded by the lack of a natural topographic drainageway within the Borough’s municipal boundary. A comprehensive plan to deal with the storm water/subsidence problems is currently being developed through the efforts of local, state, and federal agencies. A piped storm water system has received most support. This largely depends on procuring outside funding to help pay for the estimated $10 million cost.
