Abstract

Over the past century, the City of Boston has periodically experienced a decline in water table elevations and the associated deterioration of untreated timber piles which support building foundations. To combat declining water tables, Boston has instituted a groundwater conservation overlay district enforced by City zoning boards to require stormwater recharge practices for any new development or redevelopment project that increases impervious area. Brian Thomas, a Ph.D. student at Tufts University, led a study to determine if such stormwater recharge best management practices (BMPs) have had an impact on groundwater levels in Boston. Recharge to the water table in Boston results from the infiltration of rainfall and snowmelt, leakage from water mains, and recharge from man-made systems (Aldrich and Lambrechts, 1986). As water providers in Massachusetts strive to meet requirements of Massachusetts General Law Chapter 21G, which requires unaccounted-for water (e.g. leaking water pipes) to less than 10 percent (<10%), investigations have been conducted to isolate and remediate leaking water pipes throughout the city. Given the high percentage of impervious cover area of Boston, the remaining sources of recharge are primarily man-made systems, including pump and infiltrate systems and stormwater recharge BMPs. Brian Thomas was able to develop a mathematical model which predicts that the installation of recharge BMPs have a significant positive impact on groundwater levels in the Back Bay with the effect being proportional to their capacity and inversely proportional to their distance from the location of interest. The resulting models can be used to predict the impact on average well elevations at a particular location, of installing a recharge BMP (or a set of such BMPs) of a particular capacity at a particular distance from that location. Thus the model developed by Brian Thomas will have an impact on future groundwater levels in the city of Boston. The model is also novel, since it is the first of its kind and has applicability to other aging cities with building on foundations supported by wooden piles.

Submission Document

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Visit http://engineering.tufts.edu/cee/people/vogel/publications/impactStormwaterRecharge.pdf

Email richard.vogel@tufts.edu