At last, a response from the Environment Agency (EA) regarding my query about where the salt water that is entrained in the sand will end up. Actually in the end I got two responses, so that can't be bad.
From Jo Clarke:
ENV. AGENCY REF. NO: DC/2010/107842.
ENGINEERING OPERATIONS AT SEATON REGENERATION SITE, HARBOUR ROAD, SEATON.
Thank you for your e-mails and I apologise sincerely for the delay in response.
Your concerns regarding the imported fill material operations are appreciated. However, I hope it is helpful to hear that we are satisfied that the applicant has followed best practice in undertaking site investigations* and risk assessments related to controlled waters. As such, we do not consider it necessary for the site wide area to be lined.
Given the anticipated tonnage of the fill material, any saline water applied to the site during these operations will be diffused. Therefore, it is not considered likely there will be any major impact from contamination infiltrating the groundwater table. There is no point source pollution and although there will be seasonal variation in groundwater levels, the likelihood of saline intrusion into the underlying deeper aquifer is considered to be low and unlikely to have any significant impact upon this important resource.
I do hope this helps provide a measure of reassurance.
* We do not issue formal approval for risk assessment undertaken in connection with land affected by contamination. The responsibility for appropriate site investigation remains with the owner/developer. The developer takes responsibility to ensure that the development does not result in any impact to controlled waters. This should include the potential for mobilisation.
Also from Steve Moore:
Excess salt will slowly be washed out of fill material and the site by rainfall via ; a) the local man made drainage network and b) under the shingle beach to Lyme Bay.
regards steve.
So apparently not a concern for the groundwater. But if the salty water is going to be slowly washed out to the local man made drainage network, how will this impact on the extensive landscape planting. Most trees will struggle to grow in salt contaminated soil ( sand/gravel ). Most salt tolerant plants would be inadeqate in height to provide any sort of site boundary/screening.
Are EDDC monitoring salt levels in the surrounding surface water systems? If planting fails, who will be responsible for replacement and for how long will they have to keep it up?