Retention ponds and detention basins, with fountains, to promote the aerobic degradation of hydrocarbons
How it works
The local authority dictated a limited flow rate of site discharge. The client endorsed and encouraged this solution, whereby excess water is dealt with in a high quality, aesthetically pleasing way. The site has a series of ponds arranged in series, two retention ponds with permanent water and then a detention pond which remains dry most of the time.
The large amenity ponds were fed from road and car park drainage. Instead of costly oil separators to pre-treat runoff, large ornamental fountains were installed to aerate the water and promote breakdown of hydrocarbons.
Benefits and achievements
The SuDS are an integral part of the landscaping, provide amenity and added value to the office development. The area provides an amenity for office workers. The ponds were stocked with carp and silver fish, with some being subsequently removed due to overpopulation. There are normally a large number of wildfowl in the vicinity of the ponds.
The site was designed nearly 30 years ago. At that time many of the SuDS techniques now considered as best-practice were not available for use.
Consideration of infiltration trenches or stone-filled drains would now be given to supplement water treatment. Manholes were provided to allow for the retrofitting of oil interceptors, rockery inlets could have been otherwise provided to provide further aeration and aesthetic interest. The ponds could include a greater vegetated margin and accommodate more shallows and native vegetation.
The maintenance has been minimal. The fountains are inspected quarterly and a little silt build up has been noted but never removed from the ponds.