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The High Stength
Sandfilter
Minimum Dose for equal
distribution
Equation
Dose time = A + 3 B
Time Dose Equation
Measure the time required to
equally pressurize system
A= Time from pump “ON” to first
squirt
(compensate for time when no
water is coming out of the orifices)
B = Time from first squirt
to full pressure
Multiply that time by three
This will ensure water is at
equal squirt during
67%
of the run time
By this technique you we
should be able to establish a
minimum Dose size and
maintain equal distribution
Example:
360 gpd system
Time from pump being turned
ON until the first squirt shows
up is 5 seconds
A= 5 seconds
Time from the first squirt until
equal squirt is 10 seconds.
B= 10 seconds
Therefore
Minimum Dose = A + 3B
= 5 + 3 x 10
“ON Time” = 35 seconds
Set 35 seconds in the controller
Set a short OFF time
(10 Min?)
Measure drawdown over
several doses
Shows - 23.2 gallons per dose
For a 360 gpd system there
would be 15 doses
(360 divided by 23.2)
Therefore our “OFF” time is
24 divided by 15 = 1.6 hours or
1 hour 36 minutes OFF
Minimum Dose Size will be
effected by;
Design and distribution method
Ideas to minimize pump size
and dose volume
Keep tanks close to
dispersal area
Keep transport lines and
manifolds full between doses
Use chambers
on all pressurized systems to
minimize the number
of orifices needed
SURGE CAPACITY
For Time Dosing
• Pump tank needs to have enough capacity
to handle surge.
• 1,000 gallon minimum for typical
residential application
Typical 1,000 Gal Pump Chamber
Typical 500 Gal Pump Chamber
MOST IMPORTANT
Control Flow to limit
hydraulic output
DON’T FLOOD YOUR
System/Soils
Presentation
of a
Demonstration
System:
High Strength
Sand Filter
This is not a
scientific paper and
minimal data is
being presented
Hypothesis
micro-dosing
for
MACRO-ORGANISMS
BIG CRITTERS
EAT
small critters
Red Worms in Gravel Filters and
various system components
Shallow Soil Systems
At Grade Systems
Drip irrigation
Worm bin
Ghosts in Canada
Process is designed to provide an
environment that will allow macro
organisms to exist in the same area
as aerobic micro organisms, without
hydraulically over loading them.
Fall back position was that the system
is designed to rebuilt easily and cost
effectively.
Kitchen Staff
Education
Design 2000 gpd
Tanks are cheap,
put in extra grease traps
Time control of flow
70 doses per day
(every 20 minutes)
Hemlock Bark
layer above pea gravel
and sandfilter
High Strength Site Plan
High Strength Filter Profile
Chambers and Burlap
13 years Later
Flow characteristics
• 1,000 – 1,500 Gallons per day
• 4500 Gpd Peaks
• BOD5 500 TO 1100 mg/l
Construction costs
• $50,000 initial cost (7 existing 1,000 gal.
tanks were used) $21,000 saving.
• $50,000 saved not installing the aerobic
treatment portion of the system
Average Annual Fixed cost
• Approx $4,675.00 per year
• Grease Trap Pumping $3,500.00
• Quarterly inspections $800.00
• Electricity for pumps $375.00
• These costs would be incurred regardless what system was installed.
Rebuild Cost
• Approx $15,000.00
• $7,500 Labor
• $3,000 Pumping
• $4,500 materials
• Average annual cost with rebuild & repairs
Approx. $6,000.00 per year
Approx cost for sewer hook-up
• $33,000.00 hook-up fee
• $12,000 per year sewer fee
• Break even after the third year
• $60,000 saved over 13 year period
Energy Cost savings
• 2 hp blower 24/7
• 11 cents/Kw
• $1,440 per year (electricity alone) X 13 yrs
• $18,000 energy savings
Saved Maintenance Cost
• Commercial aerobic systems typically require a quarterly inspection and maintenance of the treatment portion of the system
• Approximately $1,400 per year X 13 yrs
• $18,200 saved
13 year - Impact Zones
Slime Zone
Recirculating Gravel Filter
SEPTIC TANK
RECIRCULATING
GRAVEL
FILTER
DRAINFIELD
RECIRCULATING /
MIXING TANK
Gravel Filter Profile
All four conditions must be met to satisfy media criteria.
1. Particle Size Distribution:
Sieve Particle Size Percent Passing
3/8 inch 9.50 mm 100
No. 4 4.75 mm 0 to 95
No. 8 2.36 mm 0 to 2%
No. 30 0.60 mm 0 to 0.1%
2. Effective Size: 3 mm to 5 mm.
3. Uniformity coefficient: less than or equal to 2.
4. Filter media must be washed.
Recirculating Gravel Filter Media
Recirc. Tank Profile
Flow Splitter Ball Valve
Observation
Port
To Drainfield
Buoyant Ball
Good Seal
Basket
20/80 splitter
Recirculating Gravel Filter
(Modified)
No Splitter Valve
Chamber distribution
RGF disabled alarm