Tunnel_Concrete_Floor_SOW.pdf

Fort Stanwix National Monument Rome, New York

Small tunnel / basement concrete floor

PROJECT SCOPE

NATIONAL PARK SERVICE

Northeast Region

Historic Architecture, Conservation & Engineering Center

Project location:

National Park Service, Fort Stanwix National Monument 112 East Park Street Rome, NY 13440 Location of the work area is behind the East Casemate southeast side and accessible through the lounge then into and through the arms room into the tunnel.

Project description:

To pour a concrete floor that is needed in the section of tunnel that houses the maintenance slop sink and washer & dryer hook ups. This area also has an 8” water main for the fire suppression valve train.

The new floor will have a floor drain that will be centered and tie into the existing 4” pvc waste line. By having the floor drain and having the floor height two inches lower than the casemate floor, flood waters will go down the drain and not into the casemate.

The tunnel is sectioned off with two framed insulated walls. The concrete floor will go under each wall.

Existing conditions:

This area has lighting and is not affected by outside weather conditions. The walls and ceiling are concrete. The floor is dirt and stone fill (bank run material). Currently it has a sink that is useable and some storage.

Note:

NHS staff will be responsible for removing sink and storage and cleaning up before work will start.

Floor Level

Floor will be two inches below the threshold at the door leading into the Arms room.

Ground Preparation

Ground preparation starts with removing seven to eight inches of existing fill approximately 6-7 yards. The excess fill can remain in the tunnel placed in a location chosen by the Chief of maintenance approximately 200 feet from work area. Then, if the remainder of soil has not previously been "disturbed" (i.e., dug up), a 4-in. (minimal) layer of ½” stone will be added approximately 4 yards. The stone also needs to be compacted.

Vapor Barrier

Submittal Requested Vapor barriers (essentially, thick sheets of plastic) is required. It's an inexpensive bit of insurance against water moving up through the porous concrete, condensing on the surface and damaging items placed on the slab. Vapor barrier products manufactured specifically for use under concrete.

Ready Mix

Delivery ticket required The concrete slab will be no less than 4 in. thick, minimal compressive strength 3,500 lb., slump no higher than a 6”-7” unless to pump concrete, in that case can add plasticizers to the mix that create an easier flowing mix without compromising the compressive strength. The aggregate used are based on the pumping process.

Building codes offer requirements for the concrete mix, which vary by region. The standards are expressed in terms of "compressive strength," which pretty much boils down to the amount of water used in the mix.

If you live in a cold climate, your concrete mix should probably include air-entraining agents, which limit damage to the slab through seasonal freeze-thaw cycles. Fiber reinforcement is another inexpensive product that you can use. The fibers are mixed in with the concrete and produce a stronger slab.

Concrete delivery and access for pumping

Concrete delivery and pump trucks can set up outside the fort near the sally port. The pump hose can be brought in through the exhaust vent for the tunnel.

Remove this section of duct for hose NHS staff will do this

Reinforcement

Submittal Requested Wire mesh a component of this concrete slab is required. (10 gauge 6 x 6 x 50 ft. rolls) If the reinforcement is to do its intended job, it needs to rest in the middle of the slab, not on the bottom. That means that it needs to be off the ground well enough to stay put when the concrete is poured.

Expansion Joints Submittal Requested Concrete shrinks and expands as temperature and humidity ebb and flow through the year. That's why it is necessary to include expansion joints along the edges of the slab as well as around posts or other protrusions in the slab. The resilient material (½” x 4”either asphalt or fiber can be used) expansion joints absorbs any expansion, thus reducing stress, yet fills that joint when it contracts.

Expansion joints are needed at concrete walls and around water main.

Also the need to sleeve other pvc pipes. They are five 4” roof drains, one 4” clean out and one 2” drain.

Use a 6” dia. Schedule 80 pvc pipe for roof drain and clean out also a 4” sleeve for 2” drain. Add 2” of length to be above finish floor. Fill inside of sleeve with spray urethane foam.

Installing a floor drain

The new floor will have a floor drain that will be centered and tie into the existing 4” pvc waste line. Provide a drain with a back flow preventer.

Finishing and Curing

Once concrete has been poured, it needs to be leveled around the perimeter, smoothed and pitched towards the drain with a troweled finish. Expansion grooves may be needed to be cut into the wet concrete to provide additional crack resistance. Then, the new slab needs to be left alone.

Concrete doesn't dry out; it undergoes a chemical curing process that creates a dry, solid mass. The top surface needs to remain wet while the curing process takes place.

Contractors often spray curing compound on top of the slab or cover it with sheeting to reduce evaporation.

Tie in floor drain below clean out

23’-6”

12’-0”

North

Arms Room

Dump area for fill

Roof drain

Roof drain

Roof drain

Roof drain

Water Main

Waste drain clean out

Rest room

Sink drain

Concrete floor area