Just curious to know if there is any warrant for detention basin requirement in rural development.
One argument I hear for no is that rural development is not covered in the Queensland Urban Drainage Manual. I prefer to think in terms of does the development introduce a risk that an external property will have cause to complain about it. If so, mitigation is warranted. Detention is one way to mitigate... not the best way in all circumstances though.
Detention basins on rural subdivisions ....... depends on your definition of rural. There are Rural Residential, Rural Small Holdings, Special Rural & Rural subdivisions under Planning Schemes. All of these zonings allow different sized Lots and you would need to look carefully at the lot sizes rather than have a blanket approach.
Detention basins obviously slow down the rate of water discharge off a property and remove sediment and silt which means water quality in rivers etc is greatly improved. In some of the Shires I have worked in there was also a requirement to plant native reed species to further remove sediments etc
The only problem that I have with detention basins is that they become a habitat for mosquitoes unless they are deep enough to contain water all year around, in which case you get quite a little ecosystem going so much so that in one case the detention basin had marron in it.
In short I think the advantages outweigh the disadvantages and would encourage detention basins. They are also a good source of water if required for fire fighting.
Here at Western Bay of Plenty District Council (NZ) we have a lot of rural lifestyle blocks ranging in size from say 4000m2 to 15 Ha. Normally the surrounding rural environment is large enough to mitigate any off-site stormwater effects, but in some of our areas, due to steep topography, the zoning allows for much denser development with block sizes ranging from say 2500m2 to 1Ha so houses are closer to boundaries etc.
In recognition of this our District Plan rules allows us to impose any sort of stormwater controls we feel are warranted including detention ponds, reticulation etc. Of course every development is assessed on its own merits (or otherwise). Even with detention however, be aware that traditionally, the outlet effectively concentrates the flow to one point whereas prior to development, the surface flows were sheeting off the land so sometimes you have to think about dissipating the outfall as well.
In all our zones residential, rural, commercial or lifestyle - the effects of stormwater collection and discharge is a big problem and therfore a prime consideration. Ken Lawton
I have not done any work related to detention basin. These are found from Google search, may be useful. Please check.
Thanks everyone for the contribution
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