Clean-up activity on contaminated sites

State and county officials responsible for overseeing remediation of Yorba Linda's underground contamination sites are ready to close another case, leaving just eight properties with a clean-up status labeled as “open.”

All of the sites are associated with current and former gasoline stations, and some are a legacy from pre-cityhood days, when the county Board of Supervisors loaded up Yorba Linda Boulevard with so many oil company outlets that the thoroughfare was called “gasoline alley.”

The latest--following 22 cases closed the past couple decades--involves the Yorba Linda Car Wash on Imperial Highway, just north of Los Angeles Street. The remediated site was designated as “eligible for closure” last year, and final reviews and public comment will end May 5.

Five other contaminated sites, mostly due to leaks from underground gasoline storage tanks, were labeled “eligible for closure” in 2013, but inspections and paperwork aren't yet complete.

Of course, the city's most contaminated site, the fenced-off former Ultramar station property at the southeast corner of the Imperial Highway-Lemon Drive intersection, just west of the library, has a long way to go until a “projected closure” in 2019.

Remediation on the city-owned property is ongoing, with a projected completion in 2015. Confirmation borings are anticipated by 2016, with post-remedial monitoring completed in 2018.

The latest report from the state indicates an underground “plume length exceeds water quality objectives” and ranges from 250 to 1,000 feet. The clean-up involves 17 monitoring wells.

The five “eligible for closure” sites earn the designation because “corrective action...has been determined to be completed and any remaining petroleum constituents...are considered to be low threat to human health, safety and the environment,” according to the state's criteria.

These sites include the former Union station property at Main Street and Imperial Highway, now a city-owned parking lot and home to the Farmers' Market, where a case was opened in 1987 and remediation started in 1992. A review checklist was completed March 14.

The others are the Mobile station at Yorba Linda Boulevard and Richfield Road; the Chevron station on Imperial Highway, just north of Lemon Drive; the Union station at Esperanza Road and Fairlynn Boulevard; and the Mobile station on Yorba Linda Boulevard, just south of New River Drive.

Considered on a “path to closure” are the Yorba Country Car Wash on Yorba Linda Boulevard, east of Valley View Avenue (closure projection for 2015), and the former Shell station at Yorba Linda Boulevard and Lakeview Avenue, now home to the Coffee Bean and other shops (closure projection 2016).

Should state and county officials indicate the Ultramar site is remediated by the current projection dates, the land could become part of the Town Center development, with the level of remediation determining how the site can be used.

A total 101 wells monitored clean-up activity on the nine properties.