Article - Colne Valley 'its all about the water'.

September 07, 2018

Following a recent spate of heavy rain, we have seen the flood plain of the beautiful Colne Valley transform. Water levels in the lakes have risen and are overflowing their banks, the wet woodland has emerged in all its splendour, even the footpaths have pooled up into knee deep temporary ponds creating new spaces for water-birds to enjoy.

Sadly, the construction yard the other side of Harvil Road is a different story. In October - November last year, hundreds of trees were removed in advance of a gas pipeline diversion. These enabling works involved the building of a long and winding road through a once dense forest. Views from Harvil Road at the dog’s trust show part of the extent of the destruction as heavy machinery crushes and compacts the land daily.

Recently the heavy rain falls of March and April have begun to reveal the true impact of this changing landscape. Environmental Protestors on Harvil road have witnessed and documented torrents of mud/clay slurry streaming through the construction site. The runoff now makes its way to the roadside gutter however this stretch of drainage has long been heavily blocked despite Hillingdon Councils efforts to fix this. What appears to happen is this runoff is finding its way into Newyears Green Bourne stream, where it flows straight into the Mid Colne Valley and into Lake ‘Pit 2’. The environmental consequences of any contamination are yet to be seen.

Colne Valley sits upon the prestigious Mid-Chiltern chalk aquifer which provides a significant amount of London’s drinking water. This rain water would once have seeped down through the soil, find its way to the water table and help replenish our precious fresh water supply. But sadly, the direct consequence of building on a flood plain is that this water is now lost. HS2 are responsible for the mitigation and flood impact assessments but in our opinion very little information can be ascertained from this. Here we have begun to witness the implications of large scale construction without the proper planning permission that any local project would have had to have gone through and this is only the beginning of what is to come.

Committed environmentalist and resident at the Wildlife Protection Camp, Sarah Green says: ‘The ‘wet woodland is comparable to England’s rainforest. Colne Valley is the most diverse of London’s nature reserves with over 2000 species on record. During the heavy rains of April, the water in the canal changed to a copper brown colour. There is no natural explanation for this. I am in touch with the Environment Agency and will continue to monitor the situation closely’.

How HS2 plans to deal with the threat of flooding is of utmost importance. Residential properties, businesses and the flood plain meadows with many ground nesting water birds will all be at significant risk. The implications for an oversite to occur here would be beyond words. To enjoying a walk though Harefield Moor, it is highly noticeable that the grass is completely saturated. The water is held just under the surface by various moss and grasses and you would expect this to have been revealed in any basic risk assessment. There is a great deal at stake here and HS2 need to shape up or back out.

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