Storm Drain Culvert Rehabilitation

Locations with approximate Footage: 1. Main Street, approx. 220 feet of twelve-inch corrugated steel, and approx. 455 feet of eighteen-inch corrugated metal pipe to be lined. Scope of work: 1.Three Main Street basins are to be replaced in kind per NHDOT Standards, basins 2, 3, and 5 as shown on attach overview. 2. Replace or repair top slab lid and reset frame and grate on Basin 4. Construction contractor will be required to reset any granite curbing and sidewalks repair should any be disturbed, and asphalt replacement. 3.Cleaning of the existing corrugated metal pipes to remove any obstructions that would prevent installation of the HDPE liner pipe. 4.Installation of the HDPE liner pipe through the existing pipe at excavated insertion pits. 5.Construction of all Low-Density Cellular Grout (LDCG) retaining bulk heads on the inlet/outlet ends of the lined drainage runs. 6.Furnish and pumping of LDCG material into annular space between the existing pipe and pipe liner. 7.Contractor shall place LDCG using a concrete pump and air foam generator to deliver desired pressure and wet-cast density. 8.Contractor shall ensure all voids are filled by pumping grout from upstream or downstream of culvert and continue pumping until grout is expelled from the highest vent pipe on the Inlet end. 9.Contractor shall be solely responsible for any damage or distortion of the pipe liner due to the grouting process. 10.Contractor shall comply with the pipe manufacturer's recommendations for grouting procedures. 11.Spills shall be minimized and cleaned up immediately. 12.Pipe used must be 4710 HDPE SDR32.5 liner pipe, the liner pipe will be butt fused on site per manufacturers recommendations. LDCG shall have a wet cast density of 35-50 PCF and have a minimum 300 PSI after 28-day cure, flowable fill is not an acceptable alternate to LDCG. 13.Steel plates to cover insertion pits will be allowed at the end of each workday provided they are load rated and placed following industry standards and must meet all safety guidelines. 14.Debris collection system must be always in place to prevent any entering the river. 15.All excess material must be removed from site and disposed. 16Certified traffic control personnel and signage to be provided by the contractor, with the understanding that emergency vehicles and school buses will not be delayed.

Division 03 -	Concrete, Precast Concrete.
Division 33 -	Utilities, Storm Drainage Utilities, Storm Utility Drainage Piping, Culverts, Storm Utility Water Drains, Storm Drainage Structures.