Fire units arrived within 5 minutes to find a home heating oil truck overturned on its side actively leaking from the dome cover. A representative from CT DEEP arrived at the same time as fire units and was able to apply a dome clamp to stop the leak. Fire department units along with Cheshire Public Works and DEEP contained the already leaked oil from continuing to drain into catch basins. DEEP began to identify pathways to determine the impact to local waterways and place absorbent booms. DEEP coordinated with the responsible party in securing a cleanup contractor to further mitigate and remediate. DEEP offloaded approximately 2500 gallons from the 2800-gallon truck. DEEP also recovered the contained spilled oil. Further remediation is ongoing and under the direction of CT DEEP. The driver of the truck was uninjured and was evaluated by EMS and refused transport. The CFD remained on scene until approximately 3pm to assist. Cheshire Police assisted with traffic control and is investigating the accident.