tunnels, reclaims, & soil borings

Tunnels, Reclaims, & Soil Borings

Grain Entrapment & Other Safety Areas

Presented By: Rodney Carpenter, P.E.

TUNNELS & RECLAIMS

The purpose of reclaims in tunnels is to give better access for operation, maintenance, & cleaning to both the gates & reclaim along with protecting the area from the elements

Center Unloading

Unloading Conditions

Clean

Dry

Free Flowing

In Condition

Unloading Not a Simple Process When:

• Gates plug• Grain develops clumps• Foreign items end up in the conveyors• Grain goes out of condition & becomes

non-free flowing

Off Center Unloading

Grain Facilities Today

• Grain facilities have evolved to a highly complex operation compared to the past. Today there is more automation for high volume incoming & outbound grain.

• The increase has taxed the present state of practical design. The new direction is to give a higher level of consideration to operations, safety, cleanliness, & maintenance.

History

• Facilities that handled over 2 million bushels used to be concrete clusters

• Grain bin storage was maxing out at 750k bushels per bin

• Conveying at 40k bph was high speed• Filling large dia. bins took days to weeks • Soil loads at 4000psf allowable were great

to build on.

Today

• Facilities can have over 2 million bushels in 2 corrugated bins

• A single grain bin is capable of storing 1.3 million bushels

• Conveying has moved toward 100k bph• Now able to fill large diameter bins in

hours, not days.• Geopiers, pilings, soil additives, & soil with

5000psf is being required.

Larger Grain Facility

Tunnels, Reclaims, & Soil Borings

• Tunnels– Type of tunnels– Dimensional design– Safety– Access

Types of Tunnels– No trench or tunnel

• Equipment on top of ground or floor• Conveying under aeration floors

– Equipment trench• Just wide enough for equipment• Top of equipment at surface or floor (usually)

– Equipment only tunnel• Room for equipment • No real access for operations or maintenance

– Equipment tunnel with access

No Tunnels

No Tunnels

• Floor access but below aeration floors

• Limited access to flighting, drag, or belt

• No gate access when filled with grain

• Grating over gates

Pros & Cons

Benefits• Low expense• Minimum planning• Can patch if need to

move

Drawbacks• No gate access• Not always sure gate is

closed• No access to blocked

gates• Can reach conveyor from

bin floor

Trench Only

Trench

• At top edge of concrete

• No gate access when filled with grain

• Trench should run all the way through bin

Trench

• Inside bin access by removing cover

• Flighting, chain close to the surface

• Maintenance when bin is empty

• No gate access• Grating of gates

Pros & Cons

Benefits• Low expense• Requires planning• Fixed location

Drawbacks• No gate access• Not always sure gate is

closed• Blocked gates• Can reach conveyor from

bin floor

Tunnel Equipment Only

Tunnel Equipment Only

• No access for people• Equipment takes up

the space in tunnel• Treated as a confined

space• No access to flighting,

chain, or belt from bin floor

Pros & Cons

Benefits• Requires planning• Blocked gates• Usually can not reach

conveyor from bin floor

Drawbacks• Expense• Fixed location• Poor gate access• Maintenance is difficult• Clean out is difficult• Confined space

Tunnel With Access

• Room to walk & access gates

• Room to maintenance equipment

• Easy to clean

Pros & Cons

Benefits• Requires planning• Maintenance• Clean out• Gate access• Allows for access to clean

out a blocked gate

Drawbacks• Expense• Fixed location

Location of Tunnels

• Above grade• Below grade• Part in grade &

part out

Dimension For Tunnels

• Min height of tunnel– 6’ 8” min (Nebraska)– Min height to transition

to conveyor• Width of tunnel

– Belt conveyor width add 5ft

– Chain conveyor width add 3.5ft

Nebraska

• NFPA 101 requires that above ground tunnels also be minimum 6’8” high

• Also minimum 36” clear width through the entire length of the tunnel.

• Max travel distance 50ft. for dead end or single exit

• Max travel distance in tunnels is 200ft. with 2 exits

• Max travel distance in tunnels is 400ft. if sprinkled

Dimensions for Tunnels– Keep conveyor off floor 12in no less than 6in– Keep drives outside of tunnel when possible

Access To Tunnels

• Personnel access• Equipment hatches

4-6ft. X 10ft.• Personnel access per

OSHA, Fire Marshal• Access every 100ft. • Check Nebraska

Lack of Maintenance Space

Cleaning & Maintenance

• Tunnel with lights (emergency)

• Add compressed air lines and/or water lines

• Portable vac system to pick up grain and/or dust

• Electric outlets (110V)

Cleaning Difficult

Tunnel Drainage

• Sumps in all below grade tunnels

• Crown tunnel based on soil report, usually 2-4in

• Drain outside water away from tunnel

Reclaims• Drags 5k to 40k bph

– Shorter runs– Multiple discharges– Less height to load a drag

• Enclosed Belts 20k to 80k bph– Longer runs– Single discharge– Height to load – Low horsepower

• Screws 1.5k to 10k bph– Shorter runs – Lower capacity

Loading a Reclaim

Tunnels

Walkway

Room for maintenance

Keep reclaim off the floor

Access to gates

Gates, Wells, & Sumps

Gates, Wells, & Sumps

• Location of grain sumps– Spread

• Approximately 10ft. apart• Have at least 2 sumps less than ¼ of the radius of

the bin– Sweep wheels should miss all sumps– Types

• Primary• Intermediate grain sumps

– Last sump within 3ft. to 5ft. of the bin wall

Grain Sump Capacity

• 50 to 90 bu/sq inch rule of thumb for spouting (We use 70 bu/sq inch)

• Sumps use 50 bu/sq inch when possible• Keep sumps as large as realistic for the

application

Flow Rates (bph)

Gate Size Area Max bu Normal Conservativeinches^2 90 70 50

10 by 10 120 10,800 8,400 6,000 12 by 12 144 12,960 10,080 7,200 14 by 14 196 17,640 13,720 9,800 16 by 16 256 23,040 17,920 12,800 18 by 18 324 29,160 22,680 16,200 20 by 20 400 36,000 28,000 20,000 22 by 22 484 43,560 33,880 24,200 24 by 24 576 51,840 40,320 28,800 30 by 30 900 81,000 63,000 45,000 36 by 36 1,296 116,640 90,720 64,800

Larger is better for sumps in grain bin floors

Typical Sump

Grating vs. No Grating of Sumps

• Grate sumps when flighting, chain, or belts can be reached from the bin floor

• Grate sumps next to bin entry doors• Grating will cause more blockage for grain• We recommend Grating all gates

? Which is safer: grating or dealing with sumps that will not flow…

Gates & Transitions

• Keep flow angles at 45° or greater • Access opening for probing in transition

above the gates• Keep gates easy to access• Use a key lock system on all intermediate

gates

Gate Control

Procedure • Unload center gate to bin

floor• Unlock intermediate

gates• Then unload intermediate

gates from the center out

Gate With Wheel Control

Gate Control

Gate Control

Tunnel & Reclaim Design Process

• Design equipment• Allow access left & right of reclaim• Locate sumps • Transition to gates• Transition to reclaim• Build tunnel around equipment• Crown floor keeping minimum head room

required• Add in lights, electrical, air, and/or water

Layout Sumps

Center Sump Intermediate Sump

Layout Sumps

Sumps, Transitions, & Gates

• Sump size center – 50% larger than normal flow– Sweeps will limit flow

• Gate– Center gate(s) proportional– Intermediate gates rack & pinion – Gate size, keep close to flow rate– Gates slow moving; do not slam shut!

Transitions

Transitions• Widen sumps• Place pipe connection for

probing• Transition at 45°

Gate

Clearance under conveyor

Pipeconnection

Gates & Sumps

Large

Alternate center

Probe access

Lock policy

Soil Borings

Yes!! You need them & not necessarily from the

lowest bidder!

Information Geotech’s Need

• Proposed layout • Loads of major structures

(grain bins, towers, etc.)• Allowable, piling, soil

improvement

Information DesignEngineer Needs

• Allowable soil pressure • Settlement: uniform & differential• Excavation & removal• Backfill & soil improvement options• Modulus of subgrade reaction

Information Design Engineer Needs

• Seismic site classification• Lateral earth pressures• Equivalent fluid pressure• K active• K passive• Friction coefficient for the soil

Information DesignEngineer Needs

• Water level & possible dewatering• Ram aggregate piers• Piling recommendations

Borings

• 90ft. & above– Borings: 3 equally spaced & one in center

• 80 to 54ft. – Borings: 2 equally spaced & one in center

• 48 ft. dia. – Borings: 1 in the center

Depth of Boring

• Min 40ft.• Should be about dia. of the bin• Geotech on site should make the final

determination

Thank you

Questions can be emailed to support@ccalink.com