GROUNDWATER CAPACITY AND THE MANAGEMENT OF GROWTH; HOW SUSTAINABLE WELL YIELDS GOVERN SUBURBAN SPRAWL

Throughout the Mid-Atlantic region, communities reliant on groundwater and underlain by fractured bedrock have come to look on new public groundwater supply wells with apprehension. The basis for this apprehension often is drought-related, given the focused attention on differences between initial estimates and the true long-term sustainable yield of new community supply wells.

Not uncommonly, exurban municipalities relied on yield estimates determined from relatively short pumping tests to form the basis for irrevocable lot recordation and construction approvals. When the wells came to under-perform, project proponents, consultants and permitting agencies became the subject of both scrutiny and recrimination.

Stringent capacity assessment and management guidelines have been developed by regulatory agencies in response, and hydrogeologists have developed and refined means for the conservative analysis of pumping test data. With careful reapplication, some classical pumping test data analysis techniques remain useful even in fractured bedrock. With a decreasing margin of error, long-term sustainable well yields in fractured bedrock aquifers remain a predictable function of the response of wells to properly designed pumping tests, when the data are evaluated with conservatism and experience.

As a consequence, the quality of sustainable yield forecasts has improved greatly. Public utilities and developers both have come to more fully appreciate and understand the need for appropriate conservatism more fully, and are less likely to perceive prescriptive groundwater management as backhanded growth management. This is because hydrogeologic professionals in both the regulatory community and consulting have advanced the practice of the profession and its beneficial application, meeting the challenge of accurate forecasts of sustainable well yields.