School of Medicine, Griffith University, Parklands Drive, Gold Coast, Australia; Cities Research Institute, Griffith University, Parklands Drive, Gold Coast, Australia.
School of Medicine, Griffith University, Parklands Drive, Gold Coast, Australia; Water & Health Pty Ltd, P.O. 648, Salamander Bay, 2317, Australia.
J Environ Manage. 2020 May 15;262:110309. doi: 10.1016/j.jenvman.2020.110309. Epub 2020 Feb 28.
Wet weather sewer overflows pose potential short-term public health risks. With increasing populations, aging infrastructure and climate change, utilities are challenged with managing sewerage infrastructure to provide optimum outcomes. This study compared how modelled public health risk profiles could change under alternative sewer overflow management strategies during 12 and 24-month rainfall-runoff events. Specifically, existing conditions were compared with both a 'business-as-usual' (BAU) sewer upgrade and a more holistic 'effects-based planning' (EBP) approach based on pumped wet weather sewage overflows directed to a local receiving waterway. Options were compared based on their efficacy to reduce manhole overflows, recreational waterway guideline exceedances and downstream recreational waterway health risks estimated through a screening-level Quantitative Microbial Risk Assessment (QMRA). Results indicated that the two management strategies would be equally effective in reducing the frequency, duration and volume of manhole sewer overflows, eliminating them in the 12-month scenarios and reducing them from >5000 m for the 24-month baseline scenario, to 23 and 35 m for BAU and EBP, respectively. Baseline, BAU and EBP scenarios produced similar hours of enterococci guideline exceedances, ranging from 1 to 4 h difference. The QMRA produced similar health risk profiles for downstream recreational waterway users for all design events, suggesting that sewer overflows are not the primary driver of public health risks during and immediately following high rainfall events. As such, QMRA provided evidence that an EBP strategy may be used to manage wet weather sewer overflows in lieu of an expensive BAU upgrade, without exacerbating the public health of downstream waterway users. Further investigation of the broader environmental health impacts of implementing this type of innovative approach is warranted. Nonetheless, this work highlights the value of integrating QMRA with other modelling approaches to guide and inform sewer overflow management.
多雨天气下水道溢流会带来潜在的短期公共健康风险。随着人口的增加、基础设施的老化和气候变化，公用事业公司面临着管理下水道基础设施以提供最佳结果的挑战。本研究比较了在 12 个月和 24 个月降雨径流事件中，替代下水道溢流管理策略下，模型化的公共健康风险概况如何变化。具体而言，将现有条件与“照常营业”（BAU）下水道升级以及更全面的“基于效果的规划”（EBP）方法进行了比较，后者基于将雨水污水泵送至当地受纳水道的湿天气污水溢流。根据其减少沙井溢流、娱乐性水道指导值超标和通过筛选水平定量微生物风险评估（QMRA）估计的下游娱乐性水道健康风险的效果，对方案进行了比较。结果表明，这两种管理策略在减少沙井下水道溢流的频率、持续时间和体积方面同样有效，在 12 个月的情景中消除了溢流，在 24 个月的基线情景中，将溢流从>5000 m 减少到 BAU 和 EBP 的 23 和 35 m。基线、BAU 和 EBP 情景产生了类似的肠球菌指导值超标小时数，相差 1 到 4 小时。QMRA 为所有设计事件的下游娱乐性水道使用者产生了相似的健康风险概况，表明在高降雨事件期间和之后，下水道溢流并不是公共健康风险的主要驱动因素。因此，QMRA 提供了证据，表明可以使用 EBP 策略来管理多雨天气下水道溢流，而无需升级昂贵的 BAU，而不会加剧下游水道使用者的公共健康状况。有必要进一步调查实施这种创新方法对更广泛的环境卫生影响。尽管如此，这项工作强调了将 QMRA 与其他建模方法相结合以指导和告知下水道溢流管理的价值。
