About 25 gallons of a white roofing material washed into Matadero Creek during Sunday's rainstorm.
An investigation is under way by Palo Alto fire department and city environmental officials, Ken Torke, manager of environmental control programs, confirmed Monday.
The runoff drained from a building roof on the Xerox/VM Ware campus at 3400 Hillview Ave. after a contractor had painted the surface with an acrylic elastomeric roofing material, Torke said.
The materials, which are "glorified" white paint consisting primarily of titanium oxide and a drying agent, were applied to the roof by Platinum Roofing Inc. of San Jose prior to the rainstorm but did not dry, he said.
The substances are Tresco Paint Company Elastomeric roof coating modified acrylic, product number 751; and Clear prep prime coat modified acrylic, product number 754, according to Torke.
The coatings were applied to Building 1 on Friday (Nov. 5) and to Building 2 on Saturday (Nov. 6), he said.
"The contractor stated that the material had not cured as expected due to a lower level of accelerant added to the product and lower than expected temperatures," Torke said.
The downspouts from the building connect directly to a private, on-site, storm-drain-collections system that connects to the public city system on the west side of Foothill Expressway. The city system travels under Foothill 280 feet to an outfall on Matadero Creek, Torke said.
David Coale, a Barron Park resident, observed the milky substance about 3 p.m. Sunday while walking near the footbridge at Bol Park near the donkey enclosure.
"I knew something was wrong," he said on Monday.
He called 911, but the fire department had checked out the material about four hours prior and determined it was not toxic, he said.
Coale followed the milky flow back up to its source. Close to the source, it smelled peculiar, he said.
The substance has now cleared in the lower channel near Fry's Electronics but remains somewhat cloudy in the upper reaches of the creek, Torke said.
As of Monday morning (Nov. 8), the storm drain discharge appeared clear, although some cloudy material remained in the catch basins. The creek remains cloudy, he said.
Douglas Graham, who lives on Ilima Way and has observed the creek for 40 years, said when sunlight hit the water around noon on Monday, the cloudy substance appeared blue-greenish and was "very pronounced."
"It looked like glacier milk," he said. He added that it appeared to have lessened by 3 p.m.
The creek is home to all manner of birds, insects and fish, including sticklebacks, Pacific tree frogs, crawdads and occasionally steelhead, Graham said. And he has seen his share of spills on the creek.
"I was the one that nailed the VA when they dumped wheelchair cleaner in the creek in about 1982. It killed the tree frogs. Twenty years later, the frogs are just coming back now," he said.
Considering the substance is not known to be harmful, Torke said his department is hoping there is a minimal toxicity.
"We will watch the creek for the next couple of days. We're not anticipating a long-term problem. We're hoping there is a minimal toxicity," he said.
The product safety-data indicates the two substances contain propylene glycol, polyether polyol and cabanate. The latter substance also contains bicyclic oxazol.
Both products are considered non-flammable but overexposure can cause dizziness, light-headedness and symptoms similar to alcohol inebriation. High concentrations can have a narcotic effect, the safety-data material states.
The substances can aggravate asthma, bronchitis and dermatitis. Both substances decompose into carbon dioxide and carbon monoxide, according to the data sheets.
"Stanford land management staff is working with the building owner to determine environmental concerns and additional reporting requirements. At this point they have asked the property manager to contact Fish and Game and the Regional Water Quality Control Board," Torke said.
The contractor and paint manufacturer inspected the roof and said that the material had cured to the point that no further discharges would be expected, according to Torke. The property owner and contractor are working to block the drainage to avoid further discharge, he added.
Chances are good the company will be fined. Depending on the investigation and interviews that follow, the fine could range from a few thousand dollars to up to $10,000, he said.
"A discharge did happen. That's not OK in Palo Alto," he said.