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A Way Forward (or a better Protocol). Determining which remedy: Persistent deficit (significant heave)Persistent deficit (significant heave) – Underpin.

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Presentation on theme: "A Way Forward (or a better Protocol). Determining which remedy: Persistent deficit (significant heave)Persistent deficit (significant heave) – Underpin."— Presentation transcript:

1 A Way Forward (or a better Protocol)

2 Determining which remedy: Persistent deficit (significant heave)Persistent deficit (significant heave) – Underpin with full anti-heave precautions Seasonal drying (predominantly)Seasonal drying (predominantly) – Vegetation control Fell Fell Prune Prune Root control Root control – Underpin (if tree of sufficient value)

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

4 Efficacy of investigations. PrelimAssessTrialholesSoilInvest.RootIdent.Crackmonit.LevelMonit.

5 Preliminary assessment Pattern of damage Time of development of damage Probable geology (BGS survey). Proximity and type of vegetation If conclusion probably vegetation ……

6 Efficacy of investigations. Seasonal or persistent def. Which vegetation involved. Whether remedy effective Extent and duration of heave Extent of partial underpinning. Appropriate level of proof Speedy resolution for house owner PrelimAssessTrialholesSoilInvest.RootIdent.Crackmonit.LevelMonit.

7 Other factors to consider: Ownership of the tree: Own tree Third party TPO or Conservation Area Value of the tree.

8 LTOA use CAVAT Relevant to remedial options, not to extent of investigations If the owner values the tree, it is worthy of proper investigation

9 Other factors to consider: Ownership of the tree: Own tree Third party TPO or Conservation Area Value of the tree. Number of trees / shrubs

10 Scope of investigations Desic.autumnDesic.other EssentialDesirable Useful but not necessary Waste of resources Ownership Valueoftree(s) Number of trees LevelMonit.CrackMonit.TrialholeRootIdent.Plast.index Own Tree / shrub ThirdPartytree TPO or Cons. area Low Low High High Single Single Single Single Single Many Many Many Many Many Preliminary assessment sufficient

11 Application of level monitoring Only if needed Earlier!!!!

12 Application of level monitoring Install level monitoring at first visit Install level monitoring at first visit Level distortion survey if possible Level 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 (after 12 / 18 weeks) 3rd / 4th sets of readings (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 implement action. Decide on and implement action. Continue monitoring to confirm efficacy. Continue monitoring to confirm efficacy.

13 Level monitoring with late notificationClaimnotification Setup Initialdiagnosis Confirmdiagnosis Action Confirm efficacy ONDJFMAMJJAO M o v e m e n t ( m m ) s

14 In any situation where tree-related subsidence damage is suspected, level monitoring will provide the most relevant and cost effective method of investigation. If any tree suspected of involvement is deemed to be of value by its owner, level monitoring should be the primary method of investigation. It should be commenced at the earliest opportunity. Level monitoring on its own should usually be sufficient to: 1.Confirm that the pattern of movement is consistent with the influence of trees or shrubs on a clay soil. 2.Demonstrate the extent and spatial distribution of foundation movement and its relationship to any damage. 3.Identify which trees or shrubs are likely to be involved. 4.Determine whether there is a risk of long-term heave consequent upon tree removal. 5If potentially relevant, identify the extent for partial underpinning. 6.Demonstrate whether remedial measures have been effective. Other methods of investigation, such as trial pits, soil investigations for plasticity or determination of desiccation, root identification, distortion surveys or crack monitoring are of secondary importance. They should only be necessary if there is any uncertainty in the interpretation of the results of level monitoring. The scope of any such investigations should be decided in the light of the ongoing monitoring results and designed to resolve that uncertainty. The results of level monitoring should be reviewed as each set of readings becomes available. Decisions on remedial action should be taken once the data is sufficient to show a pattern of movement consistent with the implicated tree(s) or shrubs, and then continued to determine the efficacy of the remedial action. The timing and duration of readings should be determined on such basis, and not to a pre-determined or fixed pattern. If applied correctly, in most situations level monitoring will avoid the need for other investigations, and will provide the most cost-effective, reliable and speedy resolution to the problem, to the mutual benefit of the home owner, tree owner and insurers. A Draft Protocol.

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

16 Level monitoring on its own should usually be sufficient to: 1.Confirm that the pattern of movement is consistent with the influence of trees or shrubs on a clay soil. 2.Demonstrate the extent and spatial distribution of foundation movement and its relationship to any damage. 3.Identify which trees or shrubs are likely to be involved. 4.Determine whether there is a risk of long-term heave consequent upon tree removal. 5If potentially relevant, identify the extent for partial underpinning. 6.Demonstrate whether remedial measures have been effective.

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

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

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

20 Risk assessment

21 Castellain Mansions

22 Datum April 1995 Movement Sept 1995

23 Risk assessment With suitable data, one can identify overall degree of risk With suitable data, one can identify overall degree of risk But not which individual tree poses that risk. But not which individual tree poses that risk. So should we be trying?? So should we be trying??


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