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Page 13 First Defense°Operation and Maintenance Manual a First DefenseO by Hydro International Introduction Applications The First DefenseO is an enhanced vortex separator that •Stormwater treatment at the point of entry into the drainage line combines an effective and economical stormwater treatment •Sites constrained by space,topography or drainage profiles chamberwith an integral peakflowbypass.It efficiently removes with limited slope and depth of cover total suspended solids (TSS), trash and hydrocarbons from • Retrofit installations where stormwater treatment is placed on or stormwater runoff without washing out previously captured tied into an existing storm drain line pollutants. The First Defense® is available in several model • Pretreatment for filters, infiltration and storage configurations to accommodate a wide range of pipe sizes, peak flows and depth constraints. Advantages • Inlet options include surface grate or multiple inlet pipes The two product models described in this guide are the First •Integral high capacity bypass conveys large peak flows without Defense® High Capacity and the First Defense® Optimum; the need for"offline"arrangements using separate junction they are inspected and maintained identically. manholes • Long flow path through the device ensures a long residence time within the treatment chamber, enhancing pollutant settling Operation • Delivered to site pre-assembled and ready for installation The First Defense®operates on simple fluid hydraulics. It is self- activating,has no moving parts,no external power requirement and is fabricated with durable non-corrosive components. No manual procedures are required to operate the unit and maintenance is limited to monitoring accumulations of stored pollutants and periodic clean-outs. The First Defense® has been designed to allow for easy and safe access for inspection, "" W s monitoring and clean-out procedures. Neither entry into the 1 unit nor removal of the internal components is necessary for " r=; maintenance, thus safety concerns related to confined-space- entry are avoided. Pollutant Capture and Retention � 0° ��9/��//� I�JJ10/�°�9NEE////O/!� ' NYA,01�%1111Gy011009NOONE/,t The internal components of the First Defense® have been ° �; �i%6 t i��rl designed to optimize pollutant capture. Sediment is captured and retained in the base of the unit, while oil and floatables Max oil dil �� are stored on the water surface in the inner volume(Fig.1). Storage Depth(f ii The pollutant storage volumes are isolated from the built-in bypass chamber to prevent washout during high-flow storm events. The sump of the First Defense® retains a standing y / r water level between storm events. This ensures a quiescent Sediment Sediment flow regime at the onset of a storm, preventing resuspension Storage and washout of pollutants captured during previous events. .n_...,,. ,..,., �,.. .e.,, ..e ......W , Accessories such as oil absorbent pads are available for Fig.1 Pollutant storage volumes in the First Defense® enhanced oil removal and storage. Due to the separation of the oil and floatable storage volume from the outlet, the potential for washout of stored pollutants between clean-outs is minimized.