This info-letter is the tenth entry of our series on drycleaning operations, their impact on the environment and ensuing hurdles they pose in real estate transactions.
The previous entry can be viewed here.
Sanitary Sewer - Septic Tank/Drainfield
The
sanitary sewer and septic tank/drainfield have historically been
popular disposal points for contact water. Some older drycleaning
machine service manuals even prescribed discharging contact water to
drains.
Sewer lines in urban areas can be constructed from a wide variety of
materials. Within a city, many different kinds of sewer piping may be
utilized depending on the time period the sewer lines were installed.
Older sewer lines are made of cast iron and vitrified clay and newer
lines have been constructed from concrete or more recently
thermoplastic.
Manholes were typically constructed of brick/mortar and concrete.
Early
sewer line joints were sealed with mortar and bituminous compounds.
Neither of these materials is watertight and subsequent settling and
cracking have provided pathways for contaminant migration.
Many
local sewer authorities specify permissible leakage rates for
newly-constructed sewer lines “of approximately 500 gallons per inch
diameter per day per mile.”
Contact water, free-phase solvent and solvent vapors can leak from sewer lines through cracks, joints or breaks. Contact water and free-phase solvent can also leach through sewer piping.
The more modern PVC-made sewer piping materials are not compatible with dry-cleaning solvents. There's ample evidence of PVC sewer piping being corroded and deformed by the action of dry-cleaning solvents.
Soil-gas sampling along sewer lines can be used to delineate contamination associated with leaking sewer lines.
(The information in this newsletter has been gleaned from an EPA
sponsored
site http://www.drycleancoalition.org and enhanced with pictures obtained from the Web.)
