TREE PRESERVATION ORDER: TPO No. 30/87 T1 TREE T7 of MWA Arboricultural report Works - REMOVE Reason: The above tree is considered to be responsible for root induced clay shrinkage subsidence damage to the subject property. Investigations in to the damage have been conducted and the following information/evidence obtained: 1. Engineering opinion is that damage is due to clay shrinkage subsidence. 2. Foundations are bearing on to plastic clay. 3. The clay subsoil has a high volume change potential (NHBC Guidelines). 4. A comparison between moisture content and the plastic and liquid limits suggests desiccation in TH/BH1 (January 2017). 5. Soil suctions (January 2017) indicated severe desiccation in BH1 (BRE Digest 412). Suction values of this amplitude only arise from an external force i.e. soil drying by significant vegetation. 6. Live oak roots were recovered from below foundation depth in TP/BH1 to a depth of 2.5m below ground level. 7. The observed desiccation is coincident with recorded root activity. 8. Desiccation is at depths beyond ambient soil drying effects and entirely consistent with the soil drying effects of significant vegetation. 9. Level monitoring for the period 11/06/2017 to 16/07/2018 has recorded a cyclical pattern of building movement indicative of the effects of T7 on soil moisture and volumes to the right of the property. The uplift phase of the building can only be attributable to an expanding clay soil from a desiccated state due to the soil drying effects of the trees. 10. Trees T6 and T8 of the MWA Arboricultural report were removed in September 2018. The further subsidence through the summer of 2018 confirms the ongoing influence of T7 on the soils below foundation level. 11. Drains can be discounted as a causal factor given the recorded desiccation and by reference to the level monitoring data. No significant defects were recorded to the drainage system. 12. No recent building works or alterations were undertaken prior to the occurrence of damage. 13. A root barrier is a potential alternative solution to tree removal. The current estimated cost of which is 20k for a 4.0m deep barrier. 14. Repairs are estimated to be 7,000 if the tree is removed. Underpinning localised to the affected areas of the damaged property will be needed if removal of the tree is refused. The cost of this work is estimated to exceed 70,000.

117 Avon Road Upminster RM14 1RQ