Cost to society from infiltration and inflow to wastewater systems

• Water from infiltration and inflow to wastewater systems is an extensive problem causing costs to society in various ways. Comprehensive methods for supporting decisions on how to efficiently mitigate the problems in a sustainable manner are, however, missing today. This paper presents a novel risk-based model to assess the cost to society from infiltration and inflow to wastewater systems by monetising effects related to treatment of wastewater, pumping, combined sewer overflows, and basement flooding. The present value is calculated for a specified time horizon and discount rate, using a cost-benefit analysis approach. To acknowledge the various uncertainties, a probabilistic approach is applied where probability distributions represent the input variables. The model is shown to be applicable by illustrating its use in a case study area in Gothenburg, Sweden. Main results from the case study show that most of the costs are related to investments at the wastewater treatment plant and restoration due to basement flooding events. Sensitivity analyses show that the result is highly dependent on factors such as the volume of infiltration and inflow water, the share of basement flooding, and the discount rate. Using expert elicitation to quantify input data is also illustrated and shown to be a valuable method. The presented model fills an important research knowledge gap and will facilitate a more sustainable and comprehensive handling of water from infiltration and inflow.

Subject headings

TEKNIK OCH TEKNOLOGIER  -- Samhällsbyggnadsteknik -- Vattenteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Civil Engineering -- Water Engineering (hsv//eng)

TEKNIK OCH TEKNOLOGIER  -- Naturresursteknik -- Annan naturresursteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Environmental Engineering -- Other Environmental Engineering (hsv//eng)

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Oceanografi, hydrologi och vattenresurser (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Oceanography, Hydrology and Water Resources (hsv//eng)

TEKNIK OCH TEKNOLOGIER  -- Elektroteknik och elektronik -- Annan elektroteknik och elektronik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Electrical Engineering, Electronic Engineering, Information Engineering -- Other Electrical Engineering, Electronic Engineering, Information Engineering (hsv//eng)

Keyword

Uncertainty

Sewer system

Simulation

Cost-benefit analysis

Risk-based

Decision support

Publication and Content Type

art (subject category)

ref (subject category)