Among the agreements is the creation of a new, detailed mapping system of storm drains and roadside water filters.
According to the EPA, such mapping lets the state predict where fluids will flow. That could come in handy if emergency officials are ever called to contain a tanker truck spill, for example.
Under the agreement, ADOT is also hiring more people to work in its Office of Environmental Services.
The EPA has been looking at municipal programs to reduce runoff from heavy rains since 2001, as part of its National Pollutant Discharge Elimination System.
Inspectors evaluated 57 ADOT construction sites and maintenance facilities in Tucson, Phoenix and other locations in 2010 and found room for improvement.
Rick Sakow, an EPA stormwater runoff inspector, cites a list of potentially toxic compounds that mix with rainwater after a storm:
“Pollutants from cars, like copper from brake pads and oils, as well as quite a bit of sediment.”
Sakow says runoff pollution can also come from businesses such as dry cleaners and car washes, when wastewater enters a storm drain system and mingles with other runoff. Transportation agencies like ADOT must also make sure their construction projects aren't contributing to runoff.
“It's their responsibility to do inspections of its contractors,” says Sakow. “To ensure that there are best management practices in place to keep sediment from going off-site.”
ADOT, which manages more than 18,000 miles of roadway in the state, must still address a few more issues left over from the EPA audit, but they have until March 2014 to comply.
ADOT's Storm Water Runoff Program