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Recommendations of the On -Site Wastewater Treatment Systems <br />Nitrogen Reduction Technology Expert Review Panel February 2014 <br />• Critically analyze any unintended consequences associated with the credits and any <br />potential for double- or over -counting the credits. <br />This report is intended to serve as an internal technical document for the CBPO to use to adapt <br />the existing Chesapeake Bay Model and BMP crediting program. A number of other valuable <br />resources are available to assist regulators, designers, and owners in making decisions about the <br />type of systems to install based on the benefits, drawbacks, costs, and other characteristics of <br />specific systems. Appendix A lists these resources. <br />The treatment practices initially suggested by the states to the Wastewater Treatment Workgroup <br />(WWTWG) include: <br />• Shallow -placed dispersal systems using gravity flow <br />• Secondary treatment to shallow -placed, pressure -dosed dispersal systems <br />• Denitrification unit coupled with shallow -placed, pressure -dosed distribution systems <br />The treatment practices suggested by panel members include: <br />• Sand mounds <br />• Shallow -placed drip irrigation <br />OWTS Expert Panel members were surveyed for their perspectives on issues of importance to <br />the OWTS Expert Panel's charge. Appendix B provides a summary of the survey results. Based <br />on the survey and ensuing discussions among the OWTS Expert Panel, the list of practices was <br />refined to include: <br />Ex situ or pretreatment) system components <br />• NSF Standard 40 Class I secondary systems <br />• Intermittent (single -pass) media filters <br />• Constructed wetlands (vegetated submerged beds) <br />• Recirculating media filters (RMFs) <br />• Anne Arundel County Integrated Fixed -Film Activated Sludge (IFAS) <br />• Proprietary ex situ treatment systems <br />In situ (soil treatment) system components <br />• Shallow -placed, pressure -dosed dispersal <br />• Elevated sand mounds <br />• Permeable reactive barriers <br />The charge of the OWTS Expert Panel was to only address treatment technologies. In the future, <br />the CBPO and another Expert Panel will review nitrogen attenuation in the soil between the edge <br />of the treatment system (drainfield) and the edge of the receiving water. This Attenuation Expert <br />Panel will not look at BMPs or other system modifications. <br />OTETMTECKn+c. 15 <br />