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
Tunnels, Reclaims, & Soil
Borings
– 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

• 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
Reclaims

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 Conservative
inches^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

• Sump size center
Sumps, Transitions, &
Gates
– 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
Pipe
connection
Clearance under conveyor

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 Design
Engineer 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 Design
Engineer 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