Land use regulations in the Lehigh Valley: Zoning and subdivision ordinances inan environmentally sensitive karst region

Karst subsidence is a big problem in the Lehigh Valley, the portion of the Great Valley of the Appalachians that cuts diagonally from northeast to southwest across Pennsylvania. More than $1,000,000 damage occurs each year with several single episodes exceeding $500,000. In addition, groundwater pollution has endangered the productive aquifers of the area. This paper is based on the premise that the best way to keep subsidence and groundwater problems from occurring is to stop them before they occur by placing karst concepts and safeguards in local zoning ordinances, comprehensive plans, and subdivision ordinances. Since few municipalities have zoning ordinances with karst precautions, a model ordinance was created for Lower Macungie Township in the Lehigh Valley in order to serve as a guide for other municipalities. The Lower Macungie Township Zoning Ordinance of 1989 is an example of what can be done under Act 247, the Pennsylvania Municipalities Planning Code, in protecting an area from unwise building practices on karst features. The ordinance defines certain karst features, delineates major karst features on an official map, and sets up zones where construction may not occur unless geotechnical expertise can show that there will be no ill-effect. The onus of legality is thus moved from the government body to the developer. This ordinance can be used as a model for new and or improved ordinances in other municipalities in Pennsylvania and other states.