Opponents of a controversial oil well in St. Tammany Parish were dealt a double — and possibly final — blow Wednesday when the state Supreme Court effectively ended the legal fight over the project and workers at the site began drilling the well.

The first blow came when the Supreme Court notified attorneys for the parish and a citizens group that it would not reconsider its earlier decision — on a 4-3 vote — not to entertain an appeal of a lower court’s ruling that allowed the project to go forward.

The petition to the court was a last-gasp effort, but the parish and the Concerned Citizens of St. Tammany group had little to lose by asking.

Within a couple of hours after the court’s decision became known, workers at the drill site near Lakeshore High School began drilling the 12,000-foot-deep vertical well that is phase one of the project. Drilling the well should take about 30 days, officials have said.

The company has said it is committed to drilling the well in as safe a manner as possible, and earlier Wednesday company officials led first responders on a tour of the site before conducting a mock-emergency exercise at the parish’s emergency operations center.

One major opponent of the well, Concerned Citizens of St. Tammany President Rick Franzo, said it was time to turn from the legal battle and make sure the parish is prepared to safeguard its residents and environment should something go wrong at the site.

Franzo said he was disappointed by the court’s decision but not surprised.

Despite Wednesday’s twin defeats, all is not lost for the opponents. Phase one of the project is a vertical exploratory well, from which Helis plans to collect samples to test. If the samples are promising, the company intends to return to the site, drill a mile-long horizontal shaft and use hydraulic fracturing, or fracking, to extract oil from the Tuscaloosa Marine Shale rock formation.

Company officials have said they believe there is a 50-50 chance they will choose to proceed with the project and begin fracking.

If they do, they face further hurdles, though not as daunting as the ones they already have cleared.

Helis will have to apply to the U.S. Army Corps of Engineers for a new wetlands permit for a larger drilling pad, a request that will trigger a new review and a new public comment period. The company must also apply to the state’s Office of Conservation for an amended drilling permit.

Follow Sara Pagones on Twitter, @spagonesadvocat.