Sample Project Iosco County - June 2005 Location: Iosco County, Michigan, USA Client: Iosco County Start Date: June 2, 2005 End Date: June 2, 2005

Project Scope
Iosco County retained Nautilus Marine Group International to perform an emergency inspection of a 12 foot high and 27 foot wide road culvert located on National City Road in Iosco County, Michigan.

Project Problem
During the spring of 2005 the county road commission discovered that settlement of National City road was occurring across an old culvert that connects two abandon gypsum rock quarries. The gypsum quarries are now filled with 25 feet of water.

Project Back Ground
Starting in the 1930's the National City rock quarry company mined gypsum from the surface at this location. As they expanded their mining operations they had to build a culvert under the existing road that was used for location traffic. This culvert was 12 feet high and 27 feet wide. The culvert was buried 10 feet under the existing roadway. The culvert allowed for free movement of truck traffic back and forth under the roadway.

Scope of Services
The Nautilus Marine Group International engineer dive team was comprised of a four-man dive team utilizing an engineer diver as the dive inspector, a dive supervisor and two dive technicians as the tender/standby diver. The engineer-diver employed surface supplied air diving techniques to support the underwater engineering inspections. The engineer/diver used a helmet mounted underwater video camera to document the current conditions of the culvert. All diving operations were performed from the ground at the north and south ends of the culvert. Measurements were taken that document the following conditions. Size of the structure (height length and width), thickness of the material, wing walls that were present, composition of the metal of the culvert. Depth of the sediment that is on the quarry bottom. The culvert was determined to be safe and a penetration dive was conducted to determine the condition of the culvert inside.

Inspection Results
From the penetration dive the culvert did not show any signs of distress or failure. The ends of the culvert and wing walls were marked with buoys. The underwater inspection was video taped allowing for complete baseline record to be established. This underwater inspection allowed the county engineer to look at other possible failure mechanism for the road settlement above the waterline.