Preliminary Field Evaluation of Soil Compaction in Rain Gardens

Rain gardens are implemented to mitigate runoff volume and associated pollutants to restore the health of a watershed. Rain gardens reduce runoff volume through infiltration and improve water quality as pollutants are filtered through soil media. Infiltration rates, however, can be reduced as a result of soil compaction. Knowledge about the factors that control compaction in rain gardens is currently limited, and studies are lacking on the ability of rain gardens to infiltrate runoff over a long-term period. Twenty-six rain gardens in New Jersey were evaluated during the summers of 2010 and 2011. Depth to soil compaction was measured in the field, and soil texture, site information, and oxidation-reduction potential data were collected to compare different ages of rain gardens with various soil types. There was no significant difference in soil compaction between surveys based upon the age of the rain gardens, but soil texture was found to have an influence on compaction levels. This knowledge will help to provide information on the care and maintenance of rain gardens and will help to alleviate soil compaction and increase infiltration.