Pittsburgh, Pennsylvania provides an excellent opportunity to pilot this new technology of fiber-optic based subsurface sensing, because it is afflicted by multiple geo-environmental hazards, aging infrastructure and climate change. Pittsburgh, sited at the junction of three major rivers, is characterized by varied topography, with nearly flat areas in the river floodplains, to slopes approaching 30%.

Issues of landslides and sinkholes: Pittsburgh is prone to landslides and sinkholes due to a combination of steep slopes, along with underlying geology, soils, and anthropogenic modifications such as underground mines [Pomeroy 1982; Allegheny County, 2022]. On October 28, 2019 a city bus fell into a newly developed sinkhole downtown, causing lengthy delays, power outages and costing the city nearly $100,000 to lift the bus out of the 20-ft deep hole. The sinkhole caused damage to underground utilities that took years to repair. Landslides are increasingly of concern, causing damage to infrastructure and ecosystems. Increasingly intense rainfall combined with invasive species that de-stabilize soils are exacerbating this hazard. Five million dollars was budgeted for landslide remediation in Pittsburgh for just 2023 [Glabicki and Wolfson, 2023].

Issues of aging water infrastructure and flooding: Underground water infrastructure in Pittsburgh is often decades or  more than a century old. Like most major cities in the northeastern and upper midwest US, Pittsburgh has a combined sewer system, meaning its sanitary and storm sewer systems are integrated. Thus major rain events not only cause flooding, but also sewer overflows and basement sewage backups that could have serious environmental and health impacts. Along with extensive impervious surface and associated runoff generation, and burial of smaller stream tributaries has increased flooding issues. With increasingly intense storm events due to climate change, the existing drainage network is also more frequently overwhelmed [Fischbach et al., 2018]. Cracks in pipes and junctions can also facilitate inflow and infiltration (I&I) of water into the sewer pipes during and following storm events, which further reduces pipe conveyance capacity and increases the volume of water to treat at the regional wastewater treatment plant. Pipes carrying potable water are also subject to leaks, causing losses of already-treated water.

Equity issues: There are also equity concerns related to these water infrastructure and geo-environmental hazards as they disproportionately affect low-income people and communities of color [Hendricks and Van Zandt, 2021]. Furthermore, addressing these challenges requires significant financial investment in water infrastructure, leading to rate increases that raise affordability and equity concerns in particular for more disadvantaged communities. ALCOSAN estimates that within the lowest income areas of the municipalities it serves, the current RI (Residential Indicator, measuring the percentage of a household income spent on wastewater services) can exceed 4% of the median household income, indicating a very high economic burden.