Assessing Alternative Uses of IRIS Tubes in Constructed Mitigation Wetlands.

Constructed mitigation wetlands for this project contain shallow soils over an undulating bedrock subsurface. The shallow soil is composed of topsoil harvested from permitted wetlands prior to construction impacts and vary in depth across the constructed wetland areas. The goal of the topsoil harvest was to establish a natural colonization of vegetation from a natural seed bank and maintain original soil characteristics to the extent possible.

This project assesses IRIS tubes as an alternate method of monitoring hydrology in constructed mitigation wetlands. IRIS tubes are pieces of PVC pipe coated in an iron oxide paint. They are used to determine the presence or absence of hydric soil by verifying reducing conditions are occurring in the area. When reducing conditions are present, the iron oxide paint is removed from the tube. The percent removal is calculated through a digital image analysis program to determine if reducing conditions are in fact present.

This data will be correlated to the piezometer data to assess the accuracy of IRIS tubes in terms of depth and percent removal, and if they are a sufficient replacement to piezometers or groundwater wells.

A reference wetland area is located onsite that serves as the goal of the constructed wetland cells. All data collected in this project is compared to the reference wetland to verify the constructed cells are developing comparable characteristics and trending toward a similar functionality.