The everyday test of driving skills that is the Five Corners intersection in Vineyard Haven has gained an extra degree of difficulty for the next few weeks, in the form of a yellow plastic ramp that is slowing motorists to headway speed as they traverse Beach Road and Beach street extension.

The ramp, assembled from modular parts, protects a hose carrying groundwater to Vineyard Haven harbor from the Citgo gas station, which is digging up and replacing its underground fuel tanks.

“The groundwater is so high in that location [that] they have to have a dewatering system,” town administrator John (Jay) Grande told the Gazette Monday.

After Citgo’s project manager, Adam Guaraldi, told the Tisbury select board and conservation commission that the plan has been approved by the state departments of transportation and environmental protection, the board last month granted conditional permission to run the hose down town-owned Beach street extension to the harbor.

But when the hose and ramp made their appearance last Thursday, Mr. Grande said those conditions — $1 million in liability insurance, and a waiver indemnifying the town in case of damage or injury — remained unmet.

“They put down the hose prior to giving us that indemnification — or notice,” Mr. Grande said. There also was no proof of liability insurance.

In addition to the missing documentation — and arguably of more immediate concern to Five Corners drivers — the ramping itself created a sort of reverse pothole: a high-profile hump forcing motorists to a near-standstill before performing the automotive equivalent of tiptoeing over the obstacle to continue on their way.

“The ramp system was not gradual,” said Mr. Grande, who with Tisbury public works director Kirk Metell and select board chairman James (Jimmy) Rogers descended on the worksite Friday morning to speak with Mr. Guaraldi about the deficiencies.

“We made clear that we didn’t have the indemnification and they needed to remove the hose from town property or we would remove it,” Mr. Grande said. Water pumping had not yet begun, he added.

Proofs of the indemnification and liability insurance were provided to the town late Friday, Mr. Grande said, and the ramping was extended to allow drivers a more gradual approach. However, he said, he remains concerned about public safety.

“I was not satisfied with the pedestrian access and I was not satisfied the ramping system was secure,” Mr. Grande said.

“All we can do is relay our concerns to the state and to Citgo that we want the sidewalks to still have access and the crosswalks to still have access.” Mr. Metell and the town police department will also be keeping an eye on the conditions at Beach street extension, Mr. Grande added.

The hose crossing state-owned Beach Road to the harbor via Beach street extension is expected to remain in place for the next six to eight weeks as the Citgo tank project continues, Mr. Grande said.

“It’s a pretty comprehensive replacement of everything there,” he said.

“They’re supposed to finish by end of May,” Mr. Grande said — the third and last of the conditions under which the town allowed the temporary hose installation.

Pumping groundwater to the harbor is necessary, Mr. Guaraldi told selectmen last month, because of the deteriorated condition of the sewering beneath Beach Road.

The hose will discharge the pumped water into the harbor at the location of the sewer outfall, he said.