NPL Superfund Operable Unit Boundaries (EPA Public)

This GIS dataset contains polygons depicting U.S. EPA Superfund Operable Unit boundaries. The operable unit (OU) polygons represent an individual OU’s perimeters, which are used to identify a portion of a Superfund site with which assessment and response actions are associated. CERCLA regulations (40 C.F.R. § 307.14) define an OU as a “discrete portion of a remedial response [that] manages migration, or eliminates or mitigates a release, threat of release, or pathway of exposure. The cleanup of a site can be divided into a number of operable units . . . [that] may address geographical portions of a site.” Determined on a site-specific basis, OUs may represent distinct geographic areas, media or releases. Note that OUs may overlap geographically when representing distinct media or areas of concern. OU boundaries become the building blocks of site boundaries. Superfund features are managed by regional teams of geospatial professionals and remedial program managers (RPMs), and SEGS harvests regional data on a weekly basis to refresh the national dataset and feature services.本地理信息系统（Geographic Information System, GIS）数据集包含用于描绘美国环境保护署（U.S. Environmental Protection Agency, U.S. EPA）超级基金可操作单元（Operable Unit, OU）边界的多边形要素。可操作单元多边形代表单个可操作单元的外围轮廓，用于标识超级基金场地中与评估及响应行动相关的特定区域。《综合环境反应、赔偿与责任法案》（Comprehensive Environmental Response, Compensation, and Liability Act, CERCLA）的相关法规（40 C.F.R. § 307.14）将可操作单元定义为“补救响应中的离散部分，用于管控污染物迁移、消除或减缓泄漏、泄漏威胁或暴露途径。某一场地的清理工作可划分为多个可操作单元……这些单元可针对场地的不同地理区域开展工作”。可操作单元的划定基于场地的具体情况，可代表不同的地理区域、环境介质或污染泄漏场景。需注意，当可操作单元对应不同的环境介质或关注区域时，其地理范围可能出现重叠。可操作单元边界是构建场地边界的基础模块。超级基金相关要素由地理空间专业人员与补救项目管理员（Remedial Program Managers, RPMs）组成的区域团队负责管理，SEGS每周收集区域数据以更新国家级数据集与要素服务。