MARTINEZ -- The Contra Costa zoning administrator has continued to July a compliance hearing centered on the fence line pollution monitoring system at the Phillips 66 petroleum refinery in Rodeo.

An agreement between the refinery and the Community Working Group, which consists of residents from Crockett and Rodeo, calls for the system to be functional 95 percent of the time. The agreement is incorporated into the land use permit for Phillips 66's 2007 Clean Fuels Expansion Project.

A staff report for the March 3 zoning administrator meeting had recommended a finding of compliance, noting "substantial improvement" toward the 95 percent standard, including more than 99 percent in November and December.

The Community Working Group countered that during six months of an eight-month span, the monitoring contractor, Argos Scientific Inc., found the system functioned below the 95 percent standard, including 24.1 percent of the time in September. The system worked 86.6 percent of the time in January, the last month for which measurements were available.

The fence line monitoring system is designed to detect more than a dozen substances in the air, including benzene, sulfur dioxide, nitrous oxide, carbon monoxide, toluene, xylene and methane.

The hearing will be at 3:30 p.m. July 21.

Contact Tom Lochner at 510-262-2760. Follow him at twitter.com/tomlochner