An Interceptor Trench is a good option to intercept contaminated groundwater which is perched above a relatively impermeable soil. An interceptor trench is excavated into a relatively impermeable soil layer and installed for migrating contaminated groundwater to be intercepted and collected as it flows across the impermeable layer. The trench is typically installed across a contour of a slight to a moderate sloping area to intercept groundwater prior to influencing slope stability. Generally, trenches are constructed 2 to 3 feet wide and are lined with a quality geotextile and filled with an aggregate that does not clog. There is a one to a two-foot overlap of the geotextile above the gravel and below the backfill in the trench. Water carried by the trench pipe should be conveyed to a tight line (solid pipe) which transfers water down the slope to an appropriate treatment system prior to the discharge point. Trenches can be excavated with curves and bends to prevent cutting tree roots and hitting underground utilities. Trenches can be covered with topsoil and replanted to conform to your existing ground conditions.