Client: North East Ohio Sewer District (NEORSD)
Location: Ohio, USA
Project Value: $9.87m
Description: General Contractor for Construction, Microtunnelling, Tie-Ins and Permanent Works
The project involves tie-ins to existing storm systems at both the East and West ends of the alignment. The relining of the brick culvert was completed with a “Channel Line” pipe system, under flow.
Located in an environmentally sensitive area due to construction within contaminated ground, this project had mixed conditions of medium-stiff clay’s, sands, silts and fill containing timber, tires, waste automotive parts & steel slag.
In order to reduce the construction footprint in both hazardous and contaminated ground, a value engineering proposal was agreed with the consultant and the client. The proposal included moving the shafts 2 & 3 originally located in contaminated fill to Shafts 1A & 5A, in doing so separating tie-in shafts from reception shafts, greatly reducing the overall schedule.
Tunnelling was reduced to 2 No. drives, the first drive containing 2 horizontal curves with a radius of 1640ft(500m) and 900ft(275m) and being 2400LF (732m) in length. The second contained a vertical curve of 910LF (278m). The vertical curve was included to avoid and existing culvert on the alignment which reduced the depth required for the reception shaft and provided further cost savings for the client.
During the construction of Shaft 1A, highly hazardous material was encountered which resulted in the drive length being increased by a further 322ft (98m) to the revised location of Shaft 1, situated in non-hazardous native ground. This was done to avoid encountering any further highly hazardous material. The radius of the second curve was reduced to 754ft (220m) to allow the tunnel alignment mine through Shaft 1A (Changed from a reception shaft to an intermediate shaft), through the existing 66” Brick sewer (Filled with grout from the surface to allow the MTBM safely mine through) and be received into Shaft 1, a total drive length of 2722LF (830m).