Residents living near Monterey’s Municipal Wharf may have been surprised to receive a letter from the state Department of Toxic Substances Control, asking for their comment on a planned cleanup of contaminated soils near the Monterey Sports Center.

Monterey County Health Department staff isn’t surprised by the contamination so much as by the state’s long-delayed move to clean it up. The county’s most recent document on the pollutants dates to 1991.

A manufactured gas plant occupying 2 acres on Figueroa Street near Del Monte Avenue in the early 1900s left the soil contaminated with polycyclic aromatic hydrocarbons, chemicals formed by the incomplete burning of oil and other substances. PAHs can be particularly hazardous if inhaled or ingested; some are believed to cause cancer.

Today, a PG&E electrical substation sits on one of those acres; the Sports Center occupies the other. Hazardous residues have been found in the shallow soils throughout the PG&E property, according to an April 29 letter from Richard Perry of the DTSC.

For the first three decades of the 1900s, the gas plant turned crude oil into electricity for cooking, lighting and heating. The arrival of natural gas at the end of the 1920s displaced crude oil as an energy source, and the plant was dismantled in 1934, according to county documents.

In 1986, PG&E found PAHs, heavy metals and cyanide in soil samples. PG&E’s consultant determined that the site didn’t appear to pose a risk of exposure and did not warrant further study or immediate action.

The next year, the city of Monterey sampled soil on the neighboring property, a former auto repair shop and gas station that the city would develop into the Sports Center. The city’s consultant found contaminants associated with the auto shop along with telltale PAHs, according to Eileen Woodbury, a hazardous materials specialist with the Monterey County Health Department.

“That consultant put two and two together and found out that some of the contaminants from the gas plant had migrated to the soil on the Sports Complex property,” Woodbury says.

A follow-up study by the city found pollutant residues in shallow soils and low-level contaminants in shallow groundwater. The health risks to humans and animals were minimal, the study concluded.

PG&E will do more sampling over the next year to gauge the extent of soil and groundwater contamination and work out a plan to clean it up, according to DTSC’s letter. DTSC is responsible for overseeing soil and groundwater remediation at the site, Woodbury says. Neither Perry of the DTSC nor PG&E returned calls by press time.