Study Shows Naturalized Stormwater Basin Retrofit an Asset to Municipality

F. X. Browne, Inc. recently completed a project designed to provide information on the sediment and nutrient removal capacities of a naturalized stormwater basin retrofit. 

The Montgomery Township Environmental Advisory Committee (EAC) received a Growing Greener Grant from the PA DEP to study the stormwater quality benefits of retrofitting a traditional detention basin. For the study, two basins were compared that were similar in size and capacity, and in close proximity. One basin remained a traditional stormwater detention basin while the other was converted to a naturalized wetland detention basin. The EAC retained F. X. Browne, Inc. to design and construct the basin retrofit and investigate the potential improvements in water quality and reduced stormwater runoff as a result of the study. 

As part of this project, water quality and habitat quality were assessed at each basin as a means of documenting any improvements in the naturalized basin as compared to the conventional basin. The assessments included water quality monitoring, macroinvertebrate monitoring, and biodiversity field surveys. Maintenance costs were also compared between the two basins, and a public education fact sheet was developed in order to educate township residents about the benefits of naturalized basins. 

The retrofit of the traditional basin to a naturalized stormwater wetland was a success. The wetland plants were well established at the site by the second year after construction, and the biodiversity surveys showed fewer invasive, non-native species in the naturalized basin as compared to the conventional basin. Water quality monitoring results showed increased pollutant removal efficiency in the naturalized basin as compared with the conventional basin, especially with respect to larger storms. The water quality data indicated that the naturalized basin was effective in treating high influent concentrations of solids, phosphorus, and nitrogen. Maintenance costs were also found to be significantly lower for the naturalized basin compared to the conventional basin.

To view the project report, click here (6.67 MB). For a copy of the fact sheet developed for this project, click here (1.75 MB). For more information about the project, contact info@fxbrowne.com.