Troubleshooting LPP Systems

1
Troubleshooting LPP Systems

• Taking a closer look
• OM 110 Fall 2005

2
Troubleshooting Steps

• Identify the problem
• Observe conditions
• Draw conclusions
• Test conclusions
• Fix the problem
• Check to make sure the fix works

3
Observations

• If youve been there before,
• look for things that are different from your last
  visit.
• If the system is new to you,
• look for things that dont match the
  documentation, or
• look for things that just dont make sense.

4
Bad Conclusions

• Whatever you do, dont jump

5
Seeing ? Understanding
6
The wrong approach!

• Scenario conventional line with seepage at end.
• Repair add 50 of line.
• Puts the effluent back under ground where it
  belongs for a while
• What did you fix? A symptom? (surfacing effluent)
  or a disease? (infiltration into tank, leaking
  toilet, settled distribution box, etc.)

7
Disease/symptom Cause/effect

• A single cause can have several effects
• A particular effect can result from several
  different causes.
• The operator inspection is a physical exam for
  the LPP system.

8
Anatomy 101
turnups
down hill
manifolds
laterals
valves
tanks
supply line
9
Pressurizing
turnups
down hill
manifolds
laterals
valves
tanks
10
Pressurized (Full Volume)
turnups
down hill
manifolds
laterals
valves
tanks
supply line
11
Depressurized (Draining)
turnups
down hill
manifolds
laterals
valves
tanks
12
Volumes to know

• Lateral volume how much water is actually in
  the lateral pipes when theyre full.
• Supply line manifold volume how much water is
  actually in the supply line manifold when
  theyre fully pressurized
• Draining volume (drainback) How much of the
  supply line manifold volumes drain when the
  pump shuts off .(where does it go?)

13
Pump Delivery Rate

• The rate at which water is pumped from the pump
  tank to the lateral field in gallons per minute.
  
• Controlled by two things
• Number and size of holes in laterals
• Distal pressure head
• If either of these changes, the PDR changes.

14
Pressure Head

• Design pressure head specified by the system
  designer
• Distal pressure head adjusted to the design
  pressure head in the field
• Separate valve if multiple zones

15
Distal Pressure Head

• Sloping Site The operating pressure in the
  lateral at the highest elevation in a field or
  sub-field.
• Flat site The operating pressure in the
  lateral that is farthest away from the pump.
• It is represented by the height at which water
  stands in the standpipe on the lateral when
  the pump is running.
• Set or adjust with field valve

16
Distal Pressure Head sloping site
Distal Pressure head
Slope
17
Distal lateral on a flat site
End-fed Manifolds
Distal lateral Subfield 1
Distal lateral Subfield 2
manifolds
Valves
tanks
supply line
18
Distal lateral on a flat site
Center-fed Manifold
Distal lateral
Distal lateral
Manifold
tanks
Supply line
19
Lateral head
Like distal pressure head, head in each lateral
is represented by the height of water in the
standpipe when the pump is running. Its a
combination of the head in the top lateral and
elevation difference.
Lateral head 3.2
Lateral head 2.8
Lateral head 2.0
Ground surface
Distal head 2.0
2.0
2.0
Elevation of top lateral
Elev. Diff. 0.8
Elevation of second lateral
Elev. Diff. 1.2
Elevation of third lateral
20
Remember Time to pressurize

• When the pump comes on,
• how long it takes for all the pipes to fill and,
• for the holes to start dosing at the designed
  rate
• Minimum run time for drawdown
• 3 to 5 minutes

21
INSPECTION

• Preparation ahead of time
• Check weather forecast
• Notify owner to turn off pump
• Assemble documentation
• Prepare field sheet data from last inspection
  to-do list

22
INSPECTION - performance

• Measurement recording
• Solids levels
• Pressure heads
• Drawdown
• Dosing rate
• Meter readings

23
Solids levels - what are you checking?

• Habits of occupants - FOG, a-b soaps, etc.
• In septic tank, effectiveness of primary
  treatment (settling/flotation)
• In pump tank, effectiveness of ST effluent screen
  or other pretreatment

24
Distal pressure head what are you checking?

• Difference between observed and design
• Integrity of pipe network - is effluent being
  delivered correctly to each part of the field?
• Anything within the network that alters the
  pattern blockage, breaks affects the distal
  pressure head. Where and how much the head
  changes points to where the problem is.

25
One lateral head too low

• Water thats supposed to be in the standpipe is
  going some place else. Where?
• a break in the lateral - acts like larger
  hole or extra holes
• partial blockage in lateral some of the
  water can get past
• (but this will create an increase somewhere else)

Lateral head 3.2
Lateral head 1.8
Lateral head 2.0
Ground surface
Design head 2.0
2.0
Elev. Diff. 0.8
Elevation of top lateral
Elev. Diff. 1.2
Elevation of second lateral
Elevation of third lateral
26
One lateral head too high

• Water cant leave lateral through the holes, so
  it shows up in the standpipe. Why?
• Some of the holes are blocked

Lateral head 3.2
Lateral head 3.6
Lateral head 2.0
Ground surface
Design head 2.0
2.0
Elevation of top lateral
Elev. Diff. 0.8
Elevation of second lateral
Elev. Diff. 1.2
Elevation of third lateral
27
Drawdown what are you checking?

• Drawdown x gallons/inch Dose Volume
• Slipping of floats changes dose volume

28
PDR what are you checking?

• Another view of the integrity of the pipe network
• You cant change PDR directly- it changes in
  response to other changes. This is why you should
  measure it before you make changes.

29
Meters what are you checking?

• Water meter how much water has been supplied to
  the house for a given period of time.
• If there is no outside use (irrigation, car
  washing, etc.), roughly the same amount of water
  goes to the septic tank.

30
Event counter what are you checking?

• Counts electrical events how many times has the
  pump come on?
• Gives no information about length of events
• Must know dose volume to learn how much water has
  been delivered.
• IF all the events are the same length and IF the
  dose volume hasnt changed, you can estimate how
  much water has been delivered.

31
Elapsed time meter what are you checking?

• Gives running total of how long the pump has run.
• Must know PDR to tell how much water has been
  pumped.
• IF the PDR has stayed the same, you can estimate
  how much water has been pumped.
• Measure the PDR before you make adjustments, or
  this reading isnt much use.

32
LPP troubleshooting chart

• A centerfold for operators

33
Fixing the problems

• Repair things that are broken
• Adjust things that can be adjusted
• What are you trying to change?
• What ELSE will happen?

34
OPERATIONTHE ART OF MAKING ADJUSTMENTS

• Identify changes
• Compare measurements to previous data
• Compare measurements to design specs
• Evaluate changes
• Heads too high or too low
• PDR too high or too low
• Evaluate options what can you change, and what
  will happen when you change it?

35
Changes

• If no changes have occurred within the system
  since the last time you checked it, then the
  heads and the PDR should be exactly as you left
  them.
• This is why you take baseline measurements before
  you make adjustments - to see whats changed.

36
PDR Too High

• GPM too high, but heads are okay.
• Expected amount of water is going out of lateral
  holes, and also to stand pipes but the extra is
  going somewhere. Where?
• Leak in supply line or manifold
• same thing a different way
• GPM okay, but heads are too low.

37
PDR Too Low

• GPM too low, but heads are okay.
• Water is getting to standpipes, but not enough
  is leaving lateral holes. Why?
• Blockage of lateral holes - some, many, all?
• Blocked by accumulated solids
• Blocked by roots
• Blocked by water i.e., saturation in the
  trench
• the same thing another way
• GPM okay, but heads are too high

38
PDR and head BOTH too high (or too low)

• If both parameters are off in the same direction,
  the system may just be out of adjustment.
• Use gate valve to adjust head, and then check
  dosing rate.
• If you get head adjusted correctly but dosing
  rate doesnt match, then consider possible
  causes.

39
Monitoring data checking only one lateral
Zone 1
Zone 2
40
Monitoring data Checking all laterals
Scenario 1
41
Monitoring data Checking all laterals
Scenario 2
42
Options

• What can you change?
• Operating head (distal pressure head) adjust
  valve(s)
• Dose volume adjust drawdown with floats
• Can you change dosing rate?
• What will these changes do?

43
Increase distal pressure head

• Distal pressure heads in laterals will increase
• Flow per hole will increase
• PDR will increase
• Pump run time will decrease
• Time to pressurize will decrease
• Dose volume will not change
• Distribution pattern (top to bottom) will change

44
Decrease distal pressure head

• Flow per hole and PDR will decrease
• Pump run time and time to pressurize will
  increase
• Distribution pattern will change

45
Increase drawdown

• Distal pressure head and PDR will not change
• Dose volume will increase (mind your maximum!)
• Pump run time will increase
• Time to pressurize will not change
• Doses will occur less frequently
• Distribution pattern will change, and
  overloading at bottom of system is more likely.

46
Decrease drawdown

• Heads will not change
• Dose volume and pump run time will decrease
• Doses will occur more often
• Time to pressurize will not change
• Distribution pattern will be less effective
  because length of time at operating pressure
  decreases

47
Summary of changes
48
Analyzing Meter Data
49
Using ETM readings to analyze flow

• Residence of John Smith
• 4 Bedroom home
• Demand-dosed system
• LPP distribution

50
Measuring flow ETM

51
Measuring flow ETM

52
Measuring flow ETM

53
Measuring flow ETM

54
Measuring flow ETM

55
Measuring flow ETM

56
Measuring flow ETM

57
Incoming flow Water Meter

• Know how to read the water meter

58
Comparing figures to analyze flow

• Whats happening here?

59
Analyzing flow

• What now?

60

• How much is being used relative to design?

61
Using cycle counters to analyze flow

• Bargain Flea Market
• Days of operation Fri., Sat., Sun.
• Time-dosed flow equalization
• LPP Distribution

62
(No Transcript)
63
Measuring flow Event counter
64
Measuring flow Event counter
65
Measuring flow Event counter
66
Measuring flow Event counter
67
Measuring flow Event counter
68
Measuring flow Event counter
69
Analyzing Flow Water meter
70
(No Transcript)
71
Dose Volume

• Whats the correct dose volume for a given LPP
  system?
• Minimum
• 5 x lateral volume draining volume
• Maximum
• 10 x lateral volume draining volume

72
Filling
turnups
down hill
manifolds
laterals
valves
tanks
73
Diameters and volumes

• 1 Sch. 40 4.5 gallons per 100
• 1 ¼ 7.8
• 1 ½ 10.6
• 2 17.4
• 3 38.4

480 of 1 ¼ lateral holds how much
water? 480 x 7.8 35.1 gal. Lateral
Volume 100
74
Dose volume example

• Laterals 480, 1 ¼ diameter
  35.1 gallons
• Manifold 35, 3 diameter
• portion that drains all of it 13.4 gallons
• Supply line 175, 2 diameter
• portion that drains none of it
• Minimum dose volume (5 x 35.1) 13.4
  188.9 gal
• Maximum dose volume (10 x 35.1) 13.4
  364.4 gal

75
Educated guessing

• Estimate appropriate dose volume based on lateral
  length and draining volume.
• Within that range, choose a drawdown that allows
  the pump to run for at least 5 minutes per dose.

76
Educated guessing

• Set up standpipes on all the laterals at once
• If the water levels are all the same, there is
  probably no significant blockage or leakage.

77
Educated guessing

• If you dont know what the design head is
  supposed to be, set it at 2.
• Most common starting point for systems in NC.

78
One thing at a time

• When the system needs adjusting, there are only
  two things you can change easily
• Dose volume
• Distal pressure head
• Dont try changing both at once because you
  probably wont know which one did the trick.
• In general, changing dose volume is less likely
  to cause surprises.

79
Record-keeping and reports

• For each system you operate, maintain a file
  that includes
• Copy of permit
• Copy of contracts and correspondence
• Copy of plans/specs/drawings
• Copies of previous inspection reports
• Activity log, including dates of correspondence,
  requests from owner, site visits, etc.

80

• Never, ever, take the only copy of any
  documentation to the jobsite.
• It WILL fall into the pump tank or blow away or
  get eaten by the dog.
• Make a field copy of the plans , and prepare
  a field sheet for each visit that has basic
  system info as well as data from the last
  inspection.

81
LPP Plans - the physical

• What information do you need from the plans?
• Site plan showing location of tanks, supply line,
  manifolds, laterals, valves, and any other
  components
• Piping details diameters, lengths
• Tankage details volumes, dimensions
• Pump and control specs
• Any other information that tells you whats
  buried out there

82
LPP Plans the functional

• Flow characteristics
• Design distal head
• Design dose volume
• Design system flow rate (Q)
• Total dynamic head
• Flow chart for lateral field
• These tell you how the system is meant to behave.

Used in sizing the pump
83
Flow chart
84
Flat World
85
Slope
downhill
86
To compensate for lateral/downslope water
movement,designers decrease number of holes in
lower laterals.
9 holes
7 holes
6 holes
5 holes
87
Existing systems with no documentation

• Determine nature of system
• Document current conditions
• Document findings
• Make plan of action for OM

88
No Documentation

• Operator must establish some kind of starting
  point
• Locate, measure, map, inspect, evaluate
• Determine
• Whats there
• Whats it doing
• What should be changed

89
OPERATIONTHE ART OF MAKING ADJUSTMENTS

• Identify changes
• Compare measurements to previous data
• Compare measurements to design specs
• Evaluate changes
• Heads too high or too low
• Dosing rate too high or too low
• Evaluate options what can you change, and
  what will happen?

90
It will never be perfect.

• Sometimes the heads and the dosing rate wont
  match simply because it rained yesterday.
• This is usually a self-healing problem.
• If you adjust the system its going to be out of
  whack as soon as the ground dries out.
• Schedule your next inspection for dry weather.

91
Just to reiterateThe 3 tasks of an operator
are

• Inspection
• Visually evaluate test measure record
  sample report
• Maintenance
• Repair, adjust, clean
• Operation
• Manage activities that affect the performance of
  the system
• Evaluate respond to changes diagnose problems
• Improve the function and operability of the
  system

92

• Questions?