Two people were sent to a local hospital Friday morning after two trucks overturned, blocking all northbound lanes on Interstate 575 and spilling waste materials onto the roadway. Woodstock Police Department spokeswoman Brittany Duncan said officers responded to the wreck on Towne Lake Parkway around 5 a.m. to find a box truck struck by a tractor trailer. Duncan said the tractor trailer was hauling ‘processed sludge,’ or sewage, and spewed its contents onto the interstate after overturning. Woodstock crews were tasked with cleaning up the mess prior to re-opening lanes to traffic. While three people were involved in the collision — two occupants in the box truck and one in the tractor trailer — only two were transported to Wellstar Kennestone Hospital in Marietta for treatment of non-life threatening injuries. ‘The cause of the accident is currently under investigation,’ Duncan said.