How a 1950s Dry Cleaner Can Still Affect Your Life Today
How Historic Land Use Can Impact Property Decisions
On a quiet urban street, there’s a new condo going up. The design is modern, the marketing promises healthy living, and the ground floor will soon host a café where people linger over coffee.
What no one thinks about, is that seventy years ago, this same corner housed a small dry‑cleaning business. Back then, the chemicals used to clean your clothes were poured down drains, spilled onto the ground, and handled with little thought about where they went next.
And unless those were treated, removed – they’re likely still there, more potent than ever.
Chlorinated solvents left behind by mid‑20th‑century industry continue to shape redevelopment projects, property values, indoor air quality, and environmental risk management. Even if you’ve never set foot in a dry cleaner, or worked in manufacturing, the legacy of these chemicals can still affect where you live, work, and invest.
At AEL Environment, this isn’t a hypothetical. It’s a reality we encounter regularly, often at active properties where business must continue, while complex questions are answered about human health and the environment.
What Are Chlorinated Solvents and Why Were They Everywhere?
Chlorinated solvents are a group of chemicals prized for their ability to dissolve grease, oils, and stubborn residues. For much of the 20th century, they were considered efficient, effective, and even safe.
Some of the most commonly encountered chlorinated solvents include:
- Perchloroethylene (PERC) – the backbone of traditional dry cleaning
- Trichloroethylene (TCE) – widely used for metal degreasing
- Dichloroethylene (DCE) – a breakdown product of PERC and TCE
- Vinyl Chloride (VC) – a highly toxic degradation product and known carcinogen
These compounds were used long before environmental controls like lined storage areas or safe disposal and spill‑response protocols were in place. As a result, routine operations often led to regular, undocumented releases into soil and groundwater.
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Why Chlorinated Solvents Are So Different from Other Contaminants
Not all contamination behaves the same way. Chlorinated solvents are particularly challenging because of how they move, persist, and interact with their surroundings.
1. Their Long-Term Longevity
Chlorinated solvent liquids are dense non‑aqueous phase liquids (DNAPLs), meaning they are heavier than water, and sink rather than float when released into soil or groundwater. This density allows them to migrate downward and accumulate in deeper pockets that are difficult to locate, access, and remediate.
Even after the original source has stopped, these solvents can persist underground for decades and even generations. Over time, they slowly dissolve into groundwater, continually feeding contaminant plumes and by the time contamination is discovered, the original dry cleaner, workshop, or industrial facility is often long gone, replaced by entirely different land uses and different owners.
With chlorinated solvents, time does not necessarily reduce risk.
2. Unpredictable Movement
Unlike some contaminants that tend to stay close to where they were released, or others that float in relatively predictable ways on groundwater – chlorinated solvents behave differently. Because they sink, they can move downward and sideways through fractures, permeable soil layers, and other unseen pathways in the subsurface. Over time, what began as a localized release can spread beneath neighbouring properties and far beyond where anyone would reasonably expect it to reach.
Think of a slow roof leak no one notices. The water enters high above, then quietly works its way down through walls and framing, finally showing up on the basement floor, often far from where the leak actually began.
This slow, complex migration makes chlorinated solvent contamination difficult to predict and delineate. For today’s property owners and developers, that uncertainty raises difficult questions:
- Where did the contamination originate?
- How far has it travelled?
- And who is responsible now?
These questions often emerge during redevelopment planning, property transactions, or regulatory reviews when timelines and budgets are already under pressure.
3. They Affect the Air You Breathe
Perhaps the most significant risk isn’t underground, it’s indoors.
Chlorinated solvents readily volatilize, meaning they can move from groundwater or soil into gas, and then migrate upward through cracks in foundations, service penetrations, or floor slabs. This process, known as vapour intrusion, can impact indoor air quality as evaporated solvent vapours accumulate without any visible warning signs in occupied spaces.
Where Chlorinated Solvents are Commonly Found
Based on decades of project experience, chlorinated solvent contamination is most often encountered at or near:
- Former or existing dry cleaning facilities
- Metal shops and machining operations
- Electronics manufacturing or repair sites
- Areas with historic industrial use
Many of these sites now look entirely different on the surface with mixed‑use developments, offices, institutional facilities, or as vacant land. The contamination is typically discovered during a Phase Two Environmental Site Assessment, often long after the original activity has ended.
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What This Means for Property Owners, Developers, and Communities
Chlorinated solvent contamination consequences can ripple outward if not identified and addressed early:
- Planned property transactions, financing or redevelopment can stall or collapse
- Potential off‑site migration and third‑party liability
- Reduced property value
- Regulatory complications may arise
- Health concerns related to indoor air quality
How Chlorinated Solvent Sites Are Addressed
There is no universal solution for chlorinated solvent contamination. Each site is shaped by its own geology, history, client goals and constraints and requires a tailored approach. Effective management typically involves:
- Detailed site characterization, using targeted investigation to understand where contaminants are and how they’re behaving
- Evaluation of exposure pathways, with particular focus on vapour intrusion risks
- Development of a Remedial Action Plan (RAP) that considers multiple technologies—from source treatment to engineering controls
- Implementation strategies designed to allow properties to remain operational wherever possible
Chlorinated solvent contamination has earned a reputation for being complex, costly, and disruptive and sometimes that reputation is justified. However, with proper investigation, transparent communication, and a clear technical strategy, even technically challenging sites can be managed effectively, reducing uncertainty and risk.
Looking Forward: Managing Yesterday’s Impact in Today’s World
The legacy of chlorinated solvents is a reminder that environmental decisions echo far beyond their moment in time. What was once standard practice can become tomorrow’s challenge, but that challenge doesn’t define the future of a site.
For property owners, developers, lenders, and municipalities, proactive assessment and site-specific solutions are the key difference between an unresolved environmental liability and a successful outcome.
Our team of environmental site assessors, remedial specialists and project managers support clients through every stage of decision making and implementation, bringing practical experience, technical depth, and a clear focus on real‑world outcomes.
Because sometimes, understanding what’s beneath your feet is the most important step toward building what comes next.
At AEL Environment, our team of experts are here to guide you through it – with real expertise, real accountability, and real-world results.