Answers remain hard to come by about the septic grids buried underneath Ocean Park in Oak Bluffs, after a round of drilling at the park conducted earlier this month failed to shed any light as to why treated effluent is seeping to the surface of the popular public park.

Oak Bluffs wastewater superintendent Joe Alosso said the engineering firm of Stearns & Wheler dug about six holes around the park on Dec. 15. He said the digging yielded little information about why the leeching fields are malfunctioning, although that was not entirely unexpected.

“We knew these tests might not provide conclusive information. Whatever is going on at the park is taking place underground, which of course creates difficulties,” he said.

In September the state Department of Environmental Protection bureau of resource protection issued the town a notice of noncompliance after an August inspection found the septic grids under the park were not operating properly, causing treated effluent to come to the surface periodically.

The notice of noncompliance stipulates that all breakouts of treated effluent within Ocean Park must cease immediately and gives the town until the end of this month to submit an engineering report that outlines what will be done to fix the problem.

There are 28 separate leeching fields beneath the park capable of carrying 370,000 gallons per day of treated effluent. The fields are part of a $17 million wastewater treatment system built almost a decade ago.

In recent years, there has been much debate about the source of periodic flooding at the park. Some residents have reported smelling sewage, but some wastewater officials have suggested the source was bird droppings and rotting grass.

At a special town meeting earlier this month residents voted to allocate $250,000 from the wastewater department’s retained earnings account to start addressing the problem. A portion of the money will go toward investigating the problems at Ocean Park while some will go toward relocating some or all of the septic grids to a new site next to the town wastewater plant commonly known as the Leonardo property.

Mr. Alosso said that Stearns & Wheler has already started to perform groundwater modeling as well as design and permitting work to place new leeching fields at the Leonardo property. He said the test holes at Ocean Park found some of the leeching fields had the wrong type of biological growth, indicating they may not be getting enough oxygen to perform properly.

Mr. Alosso said the information has been sent to the University of Massachusetts plant diagnostic lab for further analysis. He said he has also received a preliminary report from Stearns & Wheler indicating the seepage may be caused by the failure of the septic beds located near the bandstand.

Mr. Alosso said that Stearns & Wheler is expected to submit their final engineering report to the state department of environmental protection by Jan. 22. That report will also be shared with the wastewater commission and selectmen, he said.