Puraflo Peat Fiber Biofilter Design Package

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Puraflo & Dispersal Field Design Guide

Directions: Fill-in applicable cells in GREEN, if applicable.

Design Parameters Design flow
gpd
Occupancy
people
Soil application rate
gpd/ft2
Slope %
%
Depth to limiting layer
in
Req'd separation to limiting layer
in
Hydraulic loading per linear foot
gpd/ft
Dispersal option, req'd
Subsurface
 
 
Septic Tank Sizing Min (NSF model configuration) 500 gallons
State or Other req'd min
gallons
Septic tank size, req'd 1000 gallons
 
Pump Tank Sizing Min (NSF model configuration) 500 gallons
State or Other req'd min
gallons
Septic tank size, req'd 750 gallons
 
Puraflo Module Sizing Influent BOD5 to module
 
Module in polishing mode? No  
Puraflo modules, req'd 3  
 
In-Ground Pad Design # Pads
 
Pad, W 14.0 ft
Pad, L 64.3 ft
Pad area 900 ft2
Puraflo module spacing, ft 14.3
 
Gravel Trench Design Use bottom or sidewall area?
 
Trench, W and H, in
# Trenches 7.0  
Trench, L 64.3 ft, per trench
Bottom area 900 ft2
 
Chamber Design Use bottom or sidewall area?
 
Chamber, W and H, in
Chamber, L (per chamber)
in
# Trenches 5.0  
Trench, L 64.3 ft, per trench
Bottom area 900 ft2
Chambers, req'd 64  
Chamber model
 
Mounded Pad Design Slope ratio 3 : 1
Sand media loading rate
gpd/ft2
Absorption area width, A 4.0 ft
Absorption area length, B 56.3 ft
Basal width, A+I or A+I+J 11.4 ft, min
Mound fill depth, D 4 in
Mound fill depth, E 6 in
Mound depth, F 6 in
Mound depth, G 6 in
Mound depth, H 6 in
Downslope width, I 5.0 ft, calculated
Upslope width, J 3.7 ft, calculated
Endslope length, K 4.3 ft
Total width, W 12.6 ft
Total length, L 64.8 ft
Puraflo module spacing, M 11.7 ft, end-to-end
Total mounded pad area 816.5 ft2
4
6
6
6
6
4.1
3.5
6.6
14.2
64.3
72.8
14.3
4.3
3

Dispersal Field Water Mounding Calculation Sheet

Directions: Fill-in applicable cells in GREEN. Answers appear in BLUE.

  Design Inputs   Project Info
# of bedrooms
 
Flow per bedroom
gpd
Puraflo effluent BOD5 loading
mg/l
Pad, mounded pad or trench?
 
Pad, mounded pad or trench height, H
in
Pad, mounded pad or trench length, L
ft
Pad gravel, mounded pad sand or soil Ksat, k
gpd/ft2
Soil Ksat, k'
gpd/ft2
Soil application rate (SAR)
gpd/ft2
Minimum vertical separation (MVS) distance
in
Soil horizon 1 depth
in
Site slope %
%
 
  Design Values  
Total flow 450 gpd, or 60.2 ft3
# of Puraflo modules req'd 3  
Flow per Puraflo module, Q 150 gpd, or 20.1 ft3
Soil Ksat, k' 1.14 ft/d  
Basal radius per Puraflo module, R 2.37 ft  
Water mounding height, H 0.1 ft, or 1.2 in
Total MVS req'd 2.1 ft, or 25.2 in
Combined module basal area, Ab 53 ft2  
Pad, mounded pad or trench area per SAR 563 ft2  
Pad, mounded pad or trench area, req'd 563 ft2  
Pad, mounded pad or trench dimensions 5.6 ft W 100 ft L
Hydraulic loading per linear foot 4.5 gpd/ft  
Absorptive area width (gpd/ft + gpd/ft2) 5.6 ft  
BOD5 dispersal field loading 0.00007 lbs/d/ft2 OK
 
 
Ksat Values Rawls et al, 1998 VA AOSS Regulations, 2011
mm/h gpd/ft2 cm/d gpd/ft2
Sand 181.90 107.11 >17 >4.17
Fine Sand 141.30 83.20
Loamy Sand 123.00 72.43
Sandy Loam 55.80 32.86 10 to 17 2.45 to 4.17
Loam 6.20 3.65
Silt Loam 14.40 8.48
Sandy Clay Loam 7.70 4.53 4 to <10 0.98 to <2.45
Clay Loam 4.20 2.47
Silty Clay Loam 4.90 2.89
Sandy Clay 0.90 0.53 <4 <0.98
Silty Clay 1.80 1.06
Clay 2.00 1.18
Kaplan, 1991 Formulas1
R=√Q/πk'       H=√Q2/2kk'
1Kaplan, O. Benjamin (1991).  Septic Systems Handbook, 2nd Ed.  Lewis Publishers, Inc. Chelsea, MI.
 
Conversion Table - Hydraulic Conductivity (K)2  
m/d cm/s ft/d gpd/ft2  
1 0.00116 3.28 24.5  
864 1 2830 21200  
0.305 0.000353 1 7.48  
0.041 0.0000473 0.134 1  
2USEPA (1993).  Wellhead Protection: A Guide for Small Communities.  EPA/625/R-93/002.  USEPA. Washington, D.C.  

Dispersal Field Water Mounding Calculation Sheet

Directions: Fill-in applicable cells in GREEN. Answers appear in BLUE.

  Design Inputs  
Q Hydraulic loading
gpd 36 ft3/d  
l Length
ft  
W Width
ft  
K Hydraulic conductivity
gpd/ft2 9.71 ft/d  
SAR Soil application rate
gpd/ft2 0.08 ft/d  
D Initial depth of saturation
ft  
 
  Design Values  
R Radius of drainfield 11.2 ft  
A Drainfield area 396 ft2  
S Water mound height above saturation depth 0.1 ft  
L Distance to lateral control (absorptive width) 8.9 ft  
HLLF Hydraulic loading per linear foot 5.5 gpd/ft  
 
 

Dispersal Field Water Mounding Calculation Sheet

Directions: Fill-in applicable cells in GREEN. Answers appear in BLUE.

  Design Inputs  
Q Volumetric (hydraulic loading)
gpd 7.57 m3/d  
L Overall drainfield length
ft 42.37 m  
W Overall drainfield width
ft 14.63 m  
K1 Horizontal hydraulic conductivity, upper layer
gpd/ft2 0.35 m/d  
K1 Vertical hydraulic conductivity, lower layer
gpd/ft2 0.01 m/d  
q' Infiltration rate (if q' > Kv of upper layer, surfacing will occur) 0.30 gpd/ft2 0.01 m/d  
 
  Design Values  
Hmax Maximum water mound height 0.61 m  
2.0 ft  
Lext Lateral extent of water mounding 8.77 m  
28.8 ft  
HLLF Hydraulic loading per linear foot 0.18 m3/d/ft  
14.39 gpd/ft  
 
 

Distance to Finished Grade Calculation Sheet

Directions: Fill-in applicable cells in GREEN. Answers appear in BLUE.

  Design Inputs  
DF Design Flow
gpd
H Module bury depth + pad height
ft
S Slope
%
W Pad width
ft
L Pad length
ft
SAR Soil application rate
gpd/ft2
 
  Design Values  
B Infiltrative width required 26.6 ft
D Distance to surface 22.6 ft
HLLF Hydraulic loading per linear foot 5.6 gpd/ft
ID Infiltrative distance 20.0 ft
 
 

Image is for a design example only - numbers have no relation to calculator

Image is for a design example only - numbers have no relation to calculator

TDH Calculations for Selecting System Pump

Assumes f = 0.022 for 2 inch pipe typical operating range
Static Head in Feet = Measured/Estimated
Friction Head in Feet = (fLv2)/(2gD) = (2.1355 x 10-5)LQ2 (Q in gpm, L in feet)
Pressure Head in Feet = 0.10524(Q/No. Mod.)2 (Q in gpm) from Orifice Equations

INSTRUCTIONS:

  1. ENTER THE NUMBER OF MODULES IN BOX 1.
  2. ENTER THE STATIC HEAD IN BOX 1.
  3. ENTER THE PIPE LENGTH IN BOX 2.
  4. ENTER THE NUMBER OF FITTINGS IN BOX 2.
  5. WITH ALL ABOVE ENTERED - PLOT TDH FROM BOX 1. ON PUMP CURVE
  6. DETERMINE ANTICIPATED FLOW FROM PLOT
  7. ENTER ANTICIPATED FLOW IN BOX 3.
  8. ENTER DESIGN FLOW, DOSING INTERVAL AND TANK VOLUME PER INCH IN BOX 3.
  9. ENTER PUMP TANK VOLUME (GAL/IN) BOX 3.

BOX 1.

Q (gpm) # Modules L (feet) hstat (feet) hf (feet) hp (feet) TDH
0.0
275.00
0.00 0.00 7.00
10.0   0.59 1.17 8.76
20.0   2.35 4.68 14.03
30.0   5.29 10.52 22.81
40.0   9.40 18.71 35.11
50.0   14.68 29.23 50.91
60.0   21.14 42.10 70.24
70.0   28.78 57.30 93.07
80.0   37.58 74.84 119.42
90.0   47.57 94.72 149.28
100.0   58.73 116.93 182.66

BOX 2.

EQUIVALENT LENGTH ESTIMATE
Element 2" Ftg. Ed. Length Number Eq. Length
Length
1 100.00
Reg. 90 deg 9.00
27.00
Reg. 45 deg 4.00
5.00
T (Diversion) 11.00
55.00
Coupling (Disconnect) 2.00
2.00
Check Valve 17.00
17.00
Ball Valve (fully open) 54.00
54.00
TOTAL EQ. LENGTH   275.00

BOX 3 - Programmable Timer Settings

Anticipated pump rate
gpm From system versus pump curve for selected pump
Treatment design flow
gpd From design flow
Drainback volume per dose
gal. For cold weather climates, the transport line drains to protect from freezing
Dosing Interval (pump rest time)
hrs. Minimum 2 hours
Number of doses 12 d-1  
Drainback volume per day 0 gpd  
Pump design flow 450 gpd Treatment plus Drainback
Approx.volume per dose 38 gal.  
Dose volume per module 12.50 gal.  
Pump run time per dose 1.25 min.  
Pump run time per dose 75.00 sec.  
Tank volume (gal. per inch) ESTIMATE
gal. in.-1 From pump tank dimensions or manufacturer's data
Draw down per dose* 1.9 in. *Prior to drainback
Loss through drainback hole while pump is active is assumed to be negligible

TDH Calculations for Selecting System Pump

Assumes f = 0.02 for 3 inch pipe typical operating range
Static Head in Feet = Measured/Estimated
Friction Head in Feet = (fLv2)/(2gD) = (2.559 x 10-6)LQ2 (Q in gpm, L in feet)
Pressure Head in Feet = 0.10524(Q/No. Mod.)2 (Q in gpm) from Orifice Equations

INSTRUCTIONS:

  1. ENTER THE NUMBER OF MODULES IN BOX 1.
  2. ENTER THE STATIC HEAD IN BOX 1.
  3. ENTER THE PIPE LENGTH IN BOX 2.
  4. ENTER THE NUMBER OF FITTINGS IN BOX 2.
  5. WITH ALL ABOVE ENTERED - PLOT TDH FROM BOX 1. ON PUMP CURVE
  6. DETERMINE ANTICIPATED FLOW FROM PLOT
  7. ENTER ANTICIPATED FLOW IN BOX 3.
  8. ENTER DESIGN FLOW, DOSING INTERVAL AND TANK VOLUME PER INCH IN BOX 3.
  9. ENTER PUMP TANK VOLUME (GAL/IN) BOX 3.

BOX 1.

Q (gpm) # Modules L (feet) hstat (feet) hf (feet) hp (feet) TDH
0.0
682.00
0.00 0.00 10.00
10.0   0.17 0.21 10.39
20.0   0.70 0.86 11.56
30.0   1.57 1.93 13.50
40.0   2.79 3.44 16.23
50.0   4.36 5.37 19.73
60.0   6.28 7.73 24.01
70.0   8.55 10.52 29.08
80.0   11.17 13.75 34.92
90.0   14.14 17.40 41.53
100.0   17.45 21.48 48.93
110.0   21.12 25.99 57.11
120.0   25.13 30.93 66.06
130.0   29.49 36.30 75.79
140.0   34.21 42.10 86.30
150.0   39.27 48.32 97.59
160.0   44.68 54.98 109.66
170.0   50.44 62.07 122.51
180.0   56.55 69.56 136.13
190.0   63.00 77.53 150.54
200.0   69.81 85.91 165.72

BOX 2.

EQUIVALENT LENGTH ESTIMATE
Element 3" Ftg. Ed. Length Number Eq. Length
Length
1 300.00
Reg. 90 deg 12.00
36.00
Reg. 45 deg 6.00
60.00
T (Diversion) 17.00
17.00
Coupling (Disconnect) 4.00
4.00
Check Valve 26.00
26.00
Ball Valve (fully open) 86.00
86.00
TOTAL EQ. LENGTH   682.00

BOX 3 - Programmable Timer Settings

Anticipated pump rate
gpm From system versus pump curve for selected pump
Treatment design flow
gpd From design flow
Drainback volume per dose
gal. For cold weather climates, the transport line drains to protect from freezing
Dosing Interval (pump rest time)
hrs. Minimum 2 hours
Number of doses 12 d-1  
Drainback volume per day 0 gpd  
Pump design flow 1500 gpd Treatment plus Drainback
Approx.volume per dose 125 gal.  
Dose volume per module 12.50 gal.  
Pump run time per dose 1.25 min.  
Pump run time per dose 75.00 sec.  
Tank volume (gal. per inch) ESTIMATE
gal. in.-1 From pump tank dimensions or manufacturer's data
Draw down per dose* 4.2 in. *Prior to drainback
Loss through drainback hole while pump is active is assumed to be negligible

Drawdown Test Calculation Sheet

Directions: Fill-in applicable cells in GREEN. Answers appear in BLUE.

Gallons per Inch
Tank Type   Project Info
Round   Rectangular  
Tank or Pipe dia. (inches)
  Tank Length (inches)
 
Volume (ft3) per ft 32.15   Tank Width (inches)
 
Gallons per inch 20.04   Volume (ft3) per ft 32.10  
  Gallons per inch 20.01  
 
Drawdown Test
  Use this column if gals per in known
 
Tank Type   Tank
Round   Rectangular   Gallons per inch
Design flow (gpd)
  Design flow (gpd)
  Design flow (gpd)
Drainback vol. per dose (gal)
  Drainback vol. per dose (gal)
  Drainback vol. per dose (gal)
# Puraflo® modules
  # Puraflo® modules
  # Puraflo® modules
# doses per day
  # doses per day
  # doses per day
Drawdown (inches)
  Drawdown (inches)
  Drawdown (inches)
Elapsed time (minutes)
  Elapsed time (minutes)
  Elapsed time (minutes)
"ON" timer setting, mins 1.31   "ON" timer setting, mins 1.31   "ON" timer setting, mins 1.31
"ON" timer setting, secs 1.50   "ON" timer setting, secs 1.50   "ON" timer setting, secs 1.50
Dose volume per module 10.0   Dose volume per module 10.0   Dose volume per module 10.0

Daily Flow Calculation per Panel Readings

Directions: Fill-in applicable cells in GREEN. Answers appear in BLUE.

Design Parameters Daily design flow
gpd
Design dose
gals per dose
Days between visits
days
Pump performance per drawdown 57 gpm
 
Drawdown Information Gallons per inch
 
Drainback volume
gallons
Drawdown
in
Elapsed time
sec
Pump performance 57 gpm
Total dose volume 150  
 
Elapsed Time Meter Current reading
hr
Previous reading
hr
Elapsed time between visits 4314 min
Pump performance 57 gpm
Days between visits 75 days
Total dose volume 150  
 
Elapsed Time Meter
HH:MM:SS
Hours current reading
hr
Hours previous reading
hr
Minutes current reading
min
Minutes previous reading
min
Seconds current reading
sec
Seconds previous reading
sec
Total time between visits 0 min
Pump Performance 57 gpm
System discharge 0 gpd
 
Cycle Counter Cycle count current reading
 
Cycle count previous reading
 
Total cycles between visits 1860  
System discharge 3720 gpd