Ironically the true costs of coal tar sealants are similar to re-paving with brand new asphalt!
As we hopefully emerge from one of our nation's deepest economic slumps, considering the real cost, not just the sticker price, is as important as ever. When it comes to refined, coal tar sealers, many of the proponents of coal tar make arguments on economic grounds. "Coal tar is cheaper" and "any good business man, given two equally performing products, would pick the cheaper one" are common justifications for continuing coal tar use.
What would happen if we knew the true cost of the products? Would people continue to use coal tar if the environmental costs were included in the price of the product? Some costs we don't know just yet, like the aquatic environmental costs or human cost and probability of cancers, birth defects, and learning disabilities.
We have two real world examples where some costs are coming to light: Minnesota and Montgomery County, Maryland. They are finding high polycyclic aromatic hydrocarbons (PAHs) is stormwater treatment and flood detention basins. These facilities are designed to remove sediment (and associated contaminants) from stormwater running off of developed land. After several years of use, the ponds get full of sediment and need to be cleaned out. Typically these sediments are land applied around the ponds. No drying, hauling or landfill disposal costs.
However sampling done recently in Minnesota and Maryland, the sediments in these ponds are too high in PAHs to be land applied. Now the additional costs mentioned above must to be added to the costs of removal. The State of Minnesota estimated that if just 10% of their ponds need to be hauled to a landfill, then it would cost a staggering $1 Billion! If we estimate that this accumulation has been over the last 20 years, then here's what we have:
- People in Metro Minneapolis: 3,317,308
- Est. gallons of sealant per person: 1 (rule of thumb)
- Est. gallons applied over 20 years in just 10% of the area: 6,634,616
- Disposal cost across 10% of the area minus the cost of normal removal costs : $890,000,000
- Cost per gallon of refined coal tar sealant: $3
- Cost per gallon of low PAH, asphalt sealant: $3.60
- Cost per gallon to dispose: $134
- True cost of coal tar sealant per gallon: $137
- Cost per square foot of sealant including cleanup costs: $2.38
- Cost per square foot for New Asphalt: $2-$6