a way forward (or a better protocol). determining which remedy: persistent deficit (significant...

P.G. BiddleP.G. Biddle

A Way ForwardA Way Forward(or a better Protocol)(or a better Protocol)

Determining which remedy:Determining which remedy:• Persistent deficit Persistent deficit (significant heave)(significant heave)

– Underpin with full anti-heave precautionsUnderpin with full anti-heave precautions

• Seasonal drying Seasonal drying (predominantly)(predominantly)

– Vegetation controlVegetation control• FellFell• PrunePrune• Root controlRoot control

– Underpin (if tree of sufficient value)Underpin (if tree of sufficient value)



Information required:Information required:• Seasonal or Persistent deficitSeasonal or Persistent deficit

• Which vegetation is involved.Which vegetation is involved.

• If vegetation control, proof of whether it has If vegetation control, proof of whether it has been effective.been effective.

• Extent and duration of heave.Extent and duration of heave.

• Extent of movement for partial underpinning.Extent of movement for partial underpinning.

• Appropriate level of proof for situation.Appropriate level of proof for situation.

• Speedy resolution for house owner.Speedy resolution for house owner.

Efficacy of investigations.Efficacy of investigations.


PrelimPrelimAssessAssess

TrialTrialholesholes

SoilSoilInvest.Invest.

RootRootIdent.Ident.

CrackCrackmonit.monit.

Level Level Monit.Monit.


Preliminary assessmentPreliminary assessment

Pattern of damagePattern of damage

Time of development of damageTime of development of damage

Probable geology (BGS survey).Probable geology (BGS survey).

Proximity and type of vegetationProximity and type of vegetation

IfIf conclusion probably vegetation conclusion probably vegetation …………

Efficacy of investigations.Efficacy of investigations.


Seasonal or Seasonal or persistent def.persistent def. Which vegetationWhich vegetationinvolved.involved. Whether remedy Whether remedy effectiveeffective Extent and Extent and duration of heaveduration of heave Extent of partial Extent of partial underpinning.underpinning. Appropriate Appropriate level of prooflevel of proof Speedy resolution Speedy resolution for house ownerfor house owner

PrelimPrelimAssessAssess

TrialTrialholesholes

SoilSoilInvest.Invest.


CrackCrackmonit.monit.

Level Level Monit.Monit.


Other factors to consider:Other factors to consider:

Ownership of the tree:Ownership of the tree:Own treeOwn tree

Third partyThird party

TPO or Conservation AreaTPO or Conservation Area

Value of the tree.Value of the tree.



LTOA use CAVATLTOA use CAVATRelevant to remedial options, not to Relevant to remedial options, not to

extent of investigationsextent of investigations

If the owner values the tree, it is If the owner values the tree, it is worthy of proper investigationworthy of proper investigation


Other factors to consider:Other factors to consider:

Ownership of the tree:Ownership of the tree:Own treeOwn tree

Third partyThird party

TPO or Conservation AreaTPO or Conservation Area


Number of trees / shrubsNumber of trees / shrubs

Scope of Scope of investigationsinvestigations


Desic.Desic.autumnautumn

Desic.Desic.otherother

EssentialEssentialDesirableDesirable

Useful but not necessaryUseful but not necessaryWaste of resourcesWaste of resources

OwnerOwnershipship

ValueValueofof

tree(s)tree(s)

NumberNumberof treesof trees

LevelLevelMonit.Monit.

CrackCrackMonit.Monit.

TrialTrialholehole


Plast.Plast.indexindex

OwnOwnTree /Tree /shrubshrub

ThirdThirdPartyPartytreetree

TPO or TPO or Cons. areaCons. area

LowLow

LowLow

HighHigh

HighHigh

SingleSingle

SingleSingle

SingleSingle

SingleSingle

SingleSingle

ManyMany

ManyMany

ManyMany

ManyMany

ManyMany

Preliminary assessment sufficientPreliminary assessment sufficient


Application of level monitoring

Only if neededOnly if neededEarlier!!!!Earlier!!!!

Application of level monitoringApplication of level monitoring


• Install level monitoring at first visitInstall level monitoring at first visit• Level distortion survey if possibleLevel distortion survey if possible• 2nd set of readings (after 6 weeks) :2nd set of readings (after 6 weeks) :

• Initial diagnosis of pattern.Initial diagnosis of pattern.• Initial diagnosis of which tree(s) involved.Initial diagnosis of which tree(s) involved.• Put TP on notice. TPO application or CA notification.Put TP on notice. TPO application or CA notification.

• 3rd / 4th sets of readings 3rd / 4th sets of readings (after 12 / 18 weeks)(after 12 / 18 weeks)• Confirm diagnosis. Update TP and Local Authority.Confirm diagnosis. Update TP and Local Authority.• Consider need and location for soil investigations.Consider need and location for soil investigations.• Decide on and Decide on and implementimplement action. action.

• Continue monitoring to confirm efficacy.Continue monitoring to confirm efficacy.


Level monitoring with late notification

ClaimClaimnotificationnotification

SetSetupup InitialInitial

diagnosisdiagnosis

ConfirmConfirmdiagnosisdiagnosis

ActionAction

ConfirmConfirmefficacyefficacy

0

1

2

3

4

5

6

7

8

9

O N D J F M A M J J A O

Movement(mm)

ss

In any situation where tree-related subsidence damage is In any situation where tree-related subsidence damage is suspected, level monitoring will provide the most relevant suspected, level monitoring will provide the most relevant and cost effective method of investigation. If any tree and cost effective method of investigation. If any tree suspected of involvement is deemed to be of value by its suspected of involvement is deemed to be of value by its owner, level monitoring should be the primary method of owner, level monitoring should be the primary method of investigation. It should be commenced at the earliest investigation. It should be commenced at the earliest opportunity.opportunity. Level monitoring on its own should usually be sufficient to:Level monitoring on its own should usually be sufficient to:1.1. Confirm that the pattern of movement is Confirm that the pattern of movement is consistent with the influence of trees or shrubs consistent with the influence of trees or shrubs on a clay soil.on a clay soil.2.2. Demonstrate the extent and spatial distribution Demonstrate the extent and spatial distribution

of foundation movement and its relationship to of foundation movement and its relationship to any damage.any damage.

3.3. Identify which trees or shrubs are likely to be Identify which trees or shrubs are likely to be involved.involved.4.4. Determine whether there is a risk of long-term Determine whether there is a risk of long-term

heave consequent upon tree removal.heave consequent upon tree removal.55 If potentially relevant, identify the extent for If potentially relevant, identify the extent for partial underpinning.partial underpinning.6.6. Demonstrate whether remedial measures have Demonstrate whether remedial measures have

been effective.been effective.

Other methods of investigation, such as trial pits, soil Other methods of investigation, such as trial pits, soil investigations for plasticity or determination of desiccation, investigations for plasticity or determination of desiccation, root identification, distortion surveys or crack monitoring are of root identification, distortion surveys or crack monitoring are of secondary importance. They should only be necessary if secondary importance. They should only be necessary if there is any uncertainty in the interpretation of the results of there is any uncertainty in the interpretation of the results of level monitoring. The scope of any such investigations should level monitoring. The scope of any such investigations should be decided in the light of the ongoing monitoring results and be decided in the light of the ongoing monitoring results and designed to resolve that uncertainty.designed to resolve that uncertainty. The results of level monitoring should be reviewed as each set The results of level monitoring should be reviewed as each set of readings becomes available. Decisions on remedial action of readings becomes available. Decisions on remedial action should be taken once the data is sufficient to show a pattern of should be taken once the data is sufficient to show a pattern of movement consistent with the implicated tree(s) or shrubs, movement consistent with the implicated tree(s) or shrubs, and then continued to determine the efficacy of the remedial and then continued to determine the efficacy of the remedial action. The timing and duration of readings should be action. The timing and duration of readings should be determined on such basis, and not to a pre-determined or determined on such basis, and not to a pre-determined or fixed pattern.fixed pattern. If applied correctly, in most situations level monitoring will If applied correctly, in most situations level monitoring will avoid the need for other investigations, and will provide the avoid the need for other investigations, and will provide the most cost-effective, reliable and speedy resolution to the most cost-effective, reliable and speedy resolution to the problem, to the mutual benefit of the home owner, tree owner problem, to the mutual benefit of the home owner, tree owner and insurers.and insurers.

A Draft Protocol.A Draft Protocol.

In any situation where tree-related In any situation where tree-related subsidence damage is suspected, level subsidence damage is suspected, level monitoring will provide the most relevant monitoring will provide the most relevant and cost effective method of and cost effective method of investigation. If any tree suspected of investigation. If any tree suspected of involvement is deemed to be of value by involvement is deemed to be of value by its owner, level monitoring should be the its owner, level monitoring should be the primary method of investigation. It primary method of investigation. It should be commenced at the earliest should be commenced at the earliest opportunity.opportunity.

Level monitoring on its own should usually be sufficient to:Level monitoring on its own should usually be sufficient to:

1.1. Confirm that the pattern of movement is consistent Confirm that the pattern of movement is consistent with the influence of trees or shrubs on a clay soil.with the influence of trees or shrubs on a clay soil.2.2. Demonstrate the extent and spatial distribution of Demonstrate the extent and spatial distribution of foundation movement and its relationship to any foundation movement and its relationship to any damage.damage.3.3. Identify which trees or shrubs are likely to be Identify which trees or shrubs are likely to be involved.involved.4.4. Determine whether there is a risk of long-term Determine whether there is a risk of long-term heave heave consequent upon tree removal.consequent upon tree removal.55 If potentially relevant, identify the extent for partial If potentially relevant, identify the extent for partial underpinning.underpinning.6.6. Demonstrate whether remedial measures have been Demonstrate whether remedial measures have been

effective.effective.

Other methods of investigation, such as trial Other methods of investigation, such as trial pits, soil investigations for plasticity or pits, soil investigations for plasticity or determination of desiccation, root determination of desiccation, root identification, distortion surveys or crack identification, distortion surveys or crack monitoring are of secondary importance. monitoring are of secondary importance. They should only be necessary if there is any They should only be necessary if there is any uncertainty in the interpretation of the results uncertainty in the interpretation of the results of level monitoring. The scope of any such of level monitoring. The scope of any such investigations should be decided in the light of investigations should be decided in the light of the ongoing monitoring results and designed the ongoing monitoring results and designed to resolve that uncertainty.to resolve that uncertainty.

The results of level monitoring should be The results of level monitoring should be reviewed as each set of readings becomes reviewed as each set of readings becomes available. Decisions on remedial action available. Decisions on remedial action should be taken once the data is sufficient to should be taken once the data is sufficient to show a pattern of movement consistent with show a pattern of movement consistent with the implicated tree(s) or shrubs, and then the implicated tree(s) or shrubs, and then continued to determine the efficacy of the continued to determine the efficacy of the remedial action. The timing and duration of remedial action. The timing and duration of readings should be determined on such basis, readings should be determined on such basis, and not to a pre-determined or fixed pattern.and not to a pre-determined or fixed pattern.

If applied correctly, in most situations level If applied correctly, in most situations level monitoring will avoid the need for other monitoring will avoid the need for other investigations, and will provide the most cost-investigations, and will provide the most cost-effective, reliable and speedy resolution to effective, reliable and speedy resolution to the problem, to the mutual benefit of the the problem, to the mutual benefit of the home owner, tree owner and insurers.home owner, tree owner and insurers.


Risk assessmentRisk assessment


Castellain MansionsCastellain Mansions

Castellain Mansions


Datum April 1995Movement Sept 1995

Risk assessmentRisk assessment


• With suitable data, one can With suitable data, one can identify overall degree of riskidentify overall degree of risk

• But not which individual tree But not which individual tree poses that risk.poses that risk.

• So should we be trying??So should we be trying??

a way forward (or a better protocol). determining which remedy: persistent deficit (significant...

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