There is no permeable media at the bottom of the soakaway to get "blocked". An example borehole would be 15 metres of impermeable clay overlying a per meable strata such as chalk. The borehole is advanced through the impermeab le clay and then advanced 10 metres into the permeable strata, this interse cts many fissures within the upper chalk. An H.D.P.E. liner is then install ed inside the borehole with a minimum internal diameter of 100mm. The liner is perforated in the permeable strata and plain casing is used to line the impermeable clay. The perforated liner is then surrounded with a gravel pa ck, the plain casing is surrounded with bentonite grout which provides a pe rmanent seal to prevent any potential contamination finding its way down th e outside of the installation. A syphon head is fitted to the top of the in stallation to prevent any floating debris from entering the deep bore soaka way installation. Many new builds are now not allowed to connect to the mains drainage and ha ve to provide their own solution to drainage. In circumstances where no oth er viable drainage solution can be found, this is a cost effective solution that provides excellent results, drainage in excess of 10 litres per secon d can easily be achieved. A few contributors seem to be under the misconception that the Environment Agency are against this type of installation. The Environment Agency consid er each application to discharge water underground on a case by case basis, taking into consideration the strata that the water Is being discharged in to, where the water table is in relation to the discharge zone, and any pot ential for surface contamination finding its way into the aquifer. There ar e many circumstances where the Environment Agency have granted permission f or discharge directly into an aquifer. I have been drilling for 40 years and have never had a client come back to me and say that the soakaway has failed. We are only a local company operating in the South East of England. Althoug h we don't cover any other areas, but I am perfectly happy to take a look a t the geology of any location in mainland UK and give free advice as to whe ther this could be a solution worth pursuing. We have been to many properti es where ground workers have installed very expensive land drainage schemes which simply don't work, or fail within a few years. I have added a link to our website which has a lot of useful information on this subject, but if admin feels that this is spamming, please feel free t o delete the link.
Mark Carpenter