Increasing variability of climate-related factors, especially precipitation and temperature, poses special risks to on-site wastewater treatment systems (OWTS), which depend on subsurface saturation conditions for treatment and dispersion of wastewater. We assess OWTS fragility – the degree to which a system loses functionality – as a step to characterizing the resilience of residential wastewater treatment systems. We used the frequency and indexed severity of OWTS failures and resulting repairs to quantify fragility as a function of hydroclimate variables, including precipitation, temperature and stream flow. The frequency of each category of repair (minor, moderate and major) for 225 OWTS obtained from Boulder County public health records was modeled as a function of climate factors using a generalized linear model with a Poisson distribution link function. The results show that prolonged precipitation patterns, with monthly rainfall >10.16 cm, influence OWTS fragility, and complete loss of OWTS functionality, requiring replacement, is impacted by high temperatures, frequency of wetter-than-normal months, and the magnitude of peak stream flow in the watershed. Weather-related covariates explained 70% of the variability in OWTS major repair data between 1979 and 2006. These results indicate that fragility arising from climate factors, and associated costs to owners, environmental and health impacts, should be considered in planning, design and operation of OWTS.
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Research Article|
October 07 2016
Modeling on-site wastewater treatment system performance fragility to hydroclimate stressors Available to Purchase
Laura E. Kohler;
1Civil, Environmental, and Architectural Engineering, University of Colorado, 428 UCB, Boulder, CO 80309, USA
E-mail: [email protected]
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JoAnn Silverstein;
JoAnn Silverstein
1Civil, Environmental, and Architectural Engineering, University of Colorado, 428 UCB, Boulder, CO 80309, USA
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Balaji Rajagopalan
Balaji Rajagopalan
1Civil, Environmental, and Architectural Engineering, University of Colorado, 428 UCB, Boulder, CO 80309, USA
2Cooperative Institute for Research in Environmental Sciences, University of Colorado, 428 UCB, Boulder, CO 80309, USA
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Water Sci Technol (2016) 74 (12): 2917–2926.
Article history
Received:
June 17 2016
Accepted:
September 22 2016
Citation
Laura E. Kohler, JoAnn Silverstein, Balaji Rajagopalan; Modeling on-site wastewater treatment system performance fragility to hydroclimate stressors. Water Sci Technol 20 December 2016; 74 (12): 2917–2926. doi: https://doi.org/10.2166/wst.2016.467
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