Two bioretention cells were constructed at The Imperial Centre for arts and sciences in Rocky Mount. Both cells treat runoff from the parking lot area. It has been shown that the internal water storage layer acts as a sump to completely assimilate most events. The two cells have varying vegetative cover. One cell is a grassed system, and the other is a mulch/shrub system. The grassed cell treats a 0.54 ac, 76% impervious watershed, and the mulch/shrub cell treats a 0.61 ac, 72% impervious watershed. These cells were constructed in Winter 2006. Nutrient removal and hydrology performance were monitored at this site from 9/06-1/07 under funding by a 319 (h) grant provided by NC DENR. A report from initial monitoring was submitted on April 2007.

Monitoring resumed in September 2007 through funding from a CICEET grant which is jointly administered by Villanova University, the University of Maryland - College Park, and NC State University. The site was monitored for 16 months with a 2 ft internal water storage (IWS) layer, and it will be monitored for another 12 months at a 1 ft IWS layer to analyze the impacts of water storage depth on performance.

Monitoring Period: Funded by NCDENR - September 2006 to January 2007. Funded by CICEET - (2 ft IWS) September 2007 - January 2009, & (1 ft IWS) January 2009 - Present

Media Depth: both cells: 3 ft

Media Characteristics: 98% sand & 2% fines, low P-Index (6-15).

Drainage Configuration: both cells: internal water storage (IWS), depth 2 ft [9/06 - 1/09], & depth 1 ft [1/09 - Present].

In-situ soil: sandy-loam to sandy

Vegetative Cover: Mulch/Shrub Cell: mulch/shrub/perennials & Grassed Cell: centipede grass