Water Quality and Hydrologic Performance of a Permeable Pavement-Modular Bioretention Treatment Train and a Stormwater Filter Box in Fayetteville, North Carolina

Impervious land cover in urban developments is commonly responsible for degraded water quality and potentially erosive flow rates on downstream water bodies. Many environmental products have recently been developed to satisfy the niche in the market for easy-to-retrofit stormwater practices; however, data on the field performance of these novel stormwater control measures to reduce runoff and improve water quality are limited. Given tight site constraints, retrofitting traditional pavement with pervious pavement provides numerous water quality and hydrologic benefits. This, coupled with other treatment devices as part of a "treatment train," is becoming a valuable option to reduce a site's stormwater footprint. A permeable interlocking concrete paver (PICP) system that drains to a 1.2 m by 1.2 m Filterra® bioretention retrofit was installed at an AmtrakTM parking lot in Fayetteville, North Carolina. With a catchment-to-footprint ratio of 2.5:1, the system is designed to mitigate the 10-year storm and filter any runoff that does not infiltrate into the sandy-loam subsoil of the PICP. Additionally, a standalone, conventional Filterra® modular bioretention cell was installed on the property to mitigate impervious runoff through a curb throat. Water quality, flow, and ponding level will be monitored at five locations, including (1) impervious asphalt before the PICP, (2) underdrain leaving the PICP and entering the Filterra, (3) underdrain leaving the Filterra, (4) impervious asphalt before the conventional Filterra, and (5) the underdrain pipe leaving the conventional Filterra. Using flow-paced automatic sampling, the above locations will be monitored for total phosphorus, ortho phosphorus, total soluble phosphorus, nitrate and nitrite, Total Kjeldahl Nitrogen, total ammoniated nitrogen, total nitrogen, particle size distribution, total suspended solids, suspended sediment concentration, specific gravity, copper (Cu), zinc (Zn), and total petroleum hydrocarbons. The goal of this study is to assess the pollutant-removal performance and hydrologic mitigation ability of both proprietary treatment devices and to use these data to model PICP dynamics.