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How Detroit Water & Sewerage Department used AIM to transform sewer planning through targeted optimisation.

Client:

Detroit Water & Sewerage Department (DWSD)

Location:

Detroit, Michigan, USA

Consulting Partner:

AECOM

Asset Types:

Sewer network (foul water), pipes, CSO

AIM Version Used:

AIM 3.0

Key Outcome:

US$30m identified in avoided spend through precise, risk-based investment targeting

The Detroit Water & Sewerage Department (DWSD) serves the city of Detroit, Michigan, a historically industrial urban centre undergoing significant renewal. 

DWSD operates and maintains nearly 10,000 km (6,000 miles) of water and sewer infrastructure, much of it built in the early 20th century. In recent years, the city has committed to modernising this critical infrastructure, allocating US$500 million to sewer upgrades over a five-year period beginning in 2019. 

DWSD is responsible for safeguarding public health, protecting water quality, and supporting sustainable urban redevelopment through better infrastructure planning.

The challenge

Much of Detroit’s underground infrastructure is far beyond its original design life. 

I&I – where rainwater or groundwater enters foul sewers – was a major contributor to environmental harm, public health risk, and escalating operational costs. The city’s separate sewer and stormwater systems complicated the problem, making diagnosis and intervention planning difficult. 

DWSD needed to know not just where to act, but whether to act at all, and how to target funds for maximum long-term impact. The goal was not just renewal, but optimisation.

Who worked on this project?

AECOM, the global engineering firm, led DWSD’s capital improvement programme and acted as the primary consulting partner.

Asset management lead Andy Gibson had already been working with Probit’s AIM software through AECOM’s Global Challenge innovation programme. This in-house R&D project proved AIM’s potential for tackling I&I through advanced modelling.

After securing internal funding, AECOM partnered with DWSD to trial AIM in Detroit. Probit supported the implementation, tailoring the AIM platform to meet the specific requirements of DWSD’s sewer infrastructure and analytical needs.

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How was AIM used?

AIM 3.0 was deployed as the decision support engine behind a six-month trial in two Detroit neighbourhoods: Corktown and Midtown. Its role included:

 

  • Asset-level modelling to assess pipe condition, predict future performance, and guide interventions.
  • Risk maps integrating multiple data sources to visualise asset vulnerability and potential failure impact.
  • Scenario Builder to evaluate trade-offs across multiple investment strategies, testing risk, service, and cost outcomes.
  • Optimisation engine to identify cost-beneficial interventions or, in some cases, to show where no action was the best option.
  • Data integration from GIS systems, spreadsheets, and operational software to create a unified asset picture.

 

In practical terms, AIM helped DWSD shift from traditional cohort-level renewal planning to precise, location-specific investment targeting.

The results

The initial AIM trial delivered powerful results:

  • US$30 million in avoided spend in the pilot area by identifying interventions that offered no net benefit.
  • Average projected savings of US$4 million per year over 20 years, from better targeting and smarter scheduling.
  • A shift from reactive to proactive asset management, enabling life extension and failure avoidance.
  • Evidence-based justification for capital planning, essential for public accountability and future funding.

Perhaps most notably, AIM proved its value not only in what it recommended, but in showing where action wasn’t needed.

“ Inflow and infiltration in sewer networks pose a significant risk for many of our municipal and utility clients. The good news is technology has moved on, and by working closely with Probit and deploying their powerful modelling technology, we were able to bring a new, proactive approach to bear on this age-old problem.”

Andy Gibson
Asset Management Lead, AECOM

Technical insight

AIM’s modelling worked at true asset level, with each pipe assessed on its own terms. Risk was monetised using failure probability and consequence models, allowing cost-benefit analysis of each possible intervention.

AIM’s optimisation engine, powered by Gurobi, processed hundreds of complex trade-offs in minutes, balancing service risk, I&I reduction potential, and lifecycle cost.

In one pilot case, AIM showed that a proposed intervention was not cost-effective, guiding DWSD away from unnecessary spend. That level of clarity and precision made AIM a game-changer for I&I strategy.

What followed for DWSD and AIM?

Following the pilot’s success, DWSD commissioned a second trial using AIM in 2021.

This next phase aimed to explore the relationship between I&I and Combined Sewer Overflow (CSO) spills across a wider geographical area.

The longer-term objective is to embed AIM across DWSD’s capital planning process, expanding its role from local optimisation to network-wide strategic planning.

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