Constructed Wetland Design Practices and Performances: An Overview

Constructed wetlands are a commonly used stormwater treatment device. There are several methods used to design stormwater wetlands, each design differing in the volume of permanent water and dry detention volume above the wetland permanent water level.

This paper discusses the literature cited constructed wetland design procedures for stormwater treatment. The main design methods for wetland are: catchment area ratios, volume capture, hydraulic retention time and the kinetic (k-c*) models.

Four sets of TP10 designed wetlands (designed using TP10 specifications) were considered for four different catchment sizes. The wetland surface areas were determined by assuming average pond depths as 1.0m, 0.75m, 0.5m and 0.25m. The wetlands were assumed to comprise 60% shallow vegetated areas and 40% deeper pool areas as recommended in banded bathymetry design. Dimensions of the wetlands were calculated based on a standard 3:1 length to width ratio. Sizing methods identified from the literature and hypothetical wetlands were compared to evaluate the appropriateness of current sizing criteria. Constructed wetland performances were compared based on literature information.