WILTON — Remediation is underway following a spill of an estimated 600 to 800 gallons of home heating oil at 166 Nod Hill Road. The spill, which according to the Wilton Health Department occurred around Dec. 20, released a “significant amount” of oil onto the ground, Health Director Barry Bogle said in a letter to residents near the site. The letter was dated Dec. 30.

The state Department of Energy and Environmental Protection was notified, Bogle said, and is overseeing remediation at the site, which includes determining contamination within a 500-foot radius of the spill site.

According to information Bogle said he was given, there had been a delivery of oil and a follow-up delivery to top off the tank. While the oil was being delivered, materials under the newly installed tank gave way with the weight of the oil. That broke the service line that feeds the furnace and released all or most of the oil that was in the tank.

Bogle could not say if anyone was home at the time of the delivery, but when someone arrived they smelled oil and called the oil company.

According to the Wilton assessor’s online database, 166 Nod Hill Road is a 9.9-acre property. The health department is monitoring the cleanup and Bogle said residential wells within 500 feet will be monitored over the next four weeks.

Water samples are being collected and tested for any oil contamination. The sampling is being done by GZA GeoEnvironmental, Inc. The company’s project manager has been charged with acting as a liaison with residents.

After the four weeks of testing a decision will be made as to further sampling of wells.

Should any well test positive, residents at that address will receive bottled water, Bogle said. Further testing on any contaminated wells will be done to determine what remedial steps should be taken.

The health department expects to receive a status report each week and information will be forward to residents.

The health department may be reached at 203-563-0175.