Construct Interim Remedial Action (IRA) for the Nelson Tunnel Superfund Site - Request for Proposal (RFP)

Description: Alternative 4, drive new adit to intersect nelson tunnel, tunnel rehabilitation, install bulkhead in nelson tunnel and flow control structure in commodore 5 level and include the following remedial components. Installation of a new adit south of nelson tunnel, to bypass the nelson tunnel portal pool. Rehabilitation of nelson tunnel from the bypass adit connection to the location where bulkhead construction is planned. Installation of a flow control bulkhead in nelson tunnel to protect against a sudden uncontrolled release through nelson tunnel. Installation of an accessible bulkhead flow control structure in the commodore 5 level to protect against a sudden uncontrolled release through this level.