Wetland Delineation for 3.7 miles of I-820 in Texas

Challenge

The I-820 roadway expansion and north interchange reconfiguration at State Highway 121 to Randol Mills Road and State Highway 121 from I-820 to Handley-Ederville Road and would impact delineated jurisdictional streams and wetlands under Section 404. Avoiding impacts to the 1,500 linear-foot stream is not possible because it runs perpendicular to I-820, an existing roadway. There are no other design alternatives or facility reconfigurations that could avoid impacts to the stream while still satisfying the improvement objectives.

Solution

The existing stream will be shifted to a new location at the toe of the slope (proposed 30-foot trapezoidal open, flat bottom, grass-lined channel) that will drain into the proposed 4-7' by 6' multiple box culverts. Retaining walls are proposed to avoid encroachment on delineated wetlands.

Value

Early coordination and brainstorming amongst the engineers and the environmental scientist on the results of the delineation resulted in minimizing impacts to waters, avoiding an Individual Permit and costly mitigations on streams and wetlands.