WATERSHEDS - Water Quality Engineering in Natural Systems - page 206

TABLE 6.1. Sources of Toxic and Hazardous Substances in Urban Runoff

Source

Pollutant Automobile Use Pesticide Use Industrial/Other Use

heavy metals
Copper

Metal corrosion Algicide Paint, wood preservative,

electroplating

Lead Batteries - -

Zinc Metal corrosion, tires, road

salt

Wood preservative Paint, metal corrosion

Chromium Metal corrosion - Paint, metal corrosion,

electroplating

halogenated aliphatics
Methylene chloride - Fumigant Plastics, paint remover, solvent

Methyl chloride Gasoline Fumigant Refrigerant, solvent

Phthalate esters
Bis (2-ethylexy) phthalate - - Plasticizer

Butylbenzyl phthalate - - Plasticizer

D-N-butyl phthalate - Insecticide Plasticizer, printing inks,

paper, stain, adhesive

Polycyclic aromatic hydrocarbons
Chrysene Gasoline, oil, grease - -

Phenanthrene Gasoline - Wood/coal combustion

Pyrene Gasoline, oil, asphalt Wood preservative Wood/coal combustion

Other volatiles
Benzene Gasoline - Solvent

Chloroform Formed from salt Insecticide Solvent, formed from

chlorination

Toluene Gasoline, asphalt - Solvent

Pesticides and phenols
Lindane ( γ -BhC) - Mosquito control,

seed pretreatment

-

Chlordane - Termite control -

Dieldrin - Insecticide Wood processing

Pentachrolophenol - - Wood preservative, paint

PCBs - - Electrical, insulation (new

uses are banned in the
United States)

Asbestos
Asbestos Brake and clutch lining, tire

additives

- -

affected by washoff of contaminated solids from
impervious areas and many urban activities. Urban
pervious surfaces in humid areas are usually well
protected by vegetation and yield pollutant inputs
only during extreme storm events.
Cross-Connections and Illicit Discharges into Storm
Sewers. Illicit discharges and cross-connections
can contribute significantly to the pollutant loads
in storm sewers. Nonstormwater discharges in
storm sewers originate primarily from sewage and
industrial wastewater leaking from sanitary sewers,
failing septic tanks, groundwater infiltration con-
taining contaminated groundwater, and vehicle

maintenance activities. Deliberate dumping into
storm sewers and catch basins of used oil or waste
paint are illegal in most areas of the United States.

In some (older) cities in the United States, and in
many other countries, combined sewer overflow (CSO)
occurs and is a concern. Combined sewers carry both
storm runoff and sewage. Typically, urban combined
sewer systems are designed to carry flow that is about
four to eight times the average dry weather flow (sewage
flows), while treatment plants serving these systems are
typically designed to handle mixed flows that are four
to six times the average dry weather flow. Average