Effectiveness of highway drainage systems in preventing salt contamination of ground water, Route 25 from Wareham to the Cape Code Canal, Massachusetts

A study to determine the relative effectiveness of specially designed highway drainage features in preventing salt contamination of ground water was designed to compare four different drainage designs along a new highway in Massachusetts. At the control site, no attempt will be made to prevent salt from entering the ground. At the other three sites, different combinations of drains and impermeable berms have been designed to prevent salt contamination of ground water. To evaluate the effectiveness of the drainage designs, a salt balance will be prepared at each site over 5 years of highway use. The amount of salt applied to the highway will be compared to the amounts in the ground water or diverted to the drainage systems. Salt loads in ground water will be determined from sodium and chloride concentrations in water from about 80 wells and from aquifer porosity estimated from geophysical logs and lithologic samples. Salt loads in the drainage systems will be estimated from flow and specific conductance with the use of stage-to-discharge and conductance-to-concentrations rating curves. (USGS)