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United States Department of Agriculture

Agricultural Research Service

Title: A Low Cost Three-Dimensional Sample Collection Array to Evaluate and Monitor Constructed Wetlands

Authors
item Williams, Clinton
item Adamsen, Floyd

Submitted to: Ecological Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 15, 2007
Publication Date: May 1, 2008
Citation: Williams, C.F., Adamsen, F.J. 2008. A low cost three-dimensional sample collection array to evaluate and monitor constructed wetlands. Journal of Environmental Quality. 33:83:90

Interpretive Summary: Artifically constructed wetlands offer a low cost treatment alternative to remove a number of pollutants found in effluent water from industry, mining, agriculture, and urban areas. Sample collection to evaluate the effectiveness of treatment and to monitor the status of wetlands is usually only conducted at the inlet and outlet of the wetland due to cost constraints. To better understand the internal hydrology and biogeochemical processes operating within the wetland, more intensive sampling is needed that does not interfere with the hydraulics of the system. A low cost three-dimensional sampling array was designed and evaluated in a 1.2 ha constructed wetland. The array was designed to use off the shelf parts that would allow two people to simultaneously sample 60 locations throughout the wetland in under 30 minutes. This design will allow for increased sampling within treatment wetlands to determine better design as well as operational criteria.

Technical Abstract: Artificially constructed wetlands are gaining acceptance as a low cost treatment alternative to remove a number of undesirable constituents from water. Wetlands can be used to physically remove compounds such as suspended solids through sedimentation. Dissolved nutrients, biochemical oxygen demand (BOD), heavy metals, and potentially harmful anthropogenic compounds can all be removed in constructed wetlands through geochemical and biological processes. Sample collection to evaluate the effectiveness of treatment and to monitor the status of wetlands is usually only conducted at the inlet and outlet of the wetland due to cost constraints. To better understand the internal hydrology and biogeochemical processes operating within the wetland more intensive sampling is needed that does not interfere with the hydraulics of the system. A new relatively low cost sample collection design has been developed using mostly off-the-shelf parts that allows for permanent, internal, three dimensional sample collection in wetlands. The design has been used to construct a permanent 3-dimensional array of 60-sample locations that can be sampled simultaneously in a 1.2 ha constructed wetland for less than $5000 (US). The sampling array was used in a tracer study to characterize the internal hydraulics of the wetland. The array provided evidence of short-circuiting through the wetland as well as vertical stratification. The basic features of the system are described and examples how to construct an array that can suit any wetland design are given.

Last Modified: 10/24/2014
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