Murdock Phytoremediation

When the groundwater aquifer beneath Murdock, Nebraska was found to be contaminated by carbon tetrachloride (a carcinogenic and liver-damaging compound), the local drinking water wells were shut down and the village was connected to a rural water district. However, the contaminated groundwater was entering a local stream, and it was necessary to clean the surface water. Olsson Associates was hired by Argonne National Laboratory to design a wetland as part of an experimental phytoremediation project to rid the area of contaminated water.

The project included studies to determine the detention time needed to meet surface water quality criteria; hydrology and hydraulic studies to size the outlet structure to meet flood conveyance needs; layout of the wetland with consideration of wildlife habitat, aesthetics, and passive recreational opportunities; a planting palette for the wetland; construction observation; and regular inspections.

Features were incorporated into the wetland designs that encourage the physical reduction of carbon tetrachloride during the non-growing season, as well as biological removal during the growing season. The hydrologic regime was given important consideration. It provides water quality improvement and habitat development and maintenance. The water level is controlled by adjustable stop-logs mounted in a concrete outlet structure. The primary and secondary outlets were sized to safely pass a 100-year storm event.

An interpretive trail winds around the wetland and offers opportunities for recreational and educational activities. The wetland is also accessible for water quality monitoring and further scientific investigations, which will assist in the design and construction of future water quality wetlands to remediate contaminated groundwater.

Olsson met several objectives to successfully complete the project. The design supplements the phytoremediation site to optimize removal of carbon tetrachloride. It also protects adjacent properties from flooding and channel instability, enhances the wildlife habitat, and creates recreational and educational opportunities for Murdock citizens.