Hello everyone,
We are currently planning a new build on a plot that has been designated a floodplain since 2017, as there is a small river running behind the house. According to the neighbors currently living there, this is hard to understand, as flooding has never occurred. Nevertheless, the Hamburg water authority requires us to create a retention volume of 9.5 cubic meters (12.4 cubic yards).
What options do we have for creating such a retention area if we want to “hide” the entire volume underground or in the future garden?
One possibility would be a 10,000-liter (2,642-gallon) retention tank – but this option would be quite expensive. Do you have any other ideas on how to implement this or have you had to solve a similar problem yourselves? I would be very grateful for any practical suggestions. As mentioned, we have to assume that we will never actually need the retention volume, but we still have to present a solution together with the building permit / planning permission application.
If additional information is needed, I am happy to provide more details.
Many thanks in advance for your feedback.
Florian
We are currently planning a new build on a plot that has been designated a floodplain since 2017, as there is a small river running behind the house. According to the neighbors currently living there, this is hard to understand, as flooding has never occurred. Nevertheless, the Hamburg water authority requires us to create a retention volume of 9.5 cubic meters (12.4 cubic yards).
What options do we have for creating such a retention area if we want to “hide” the entire volume underground or in the future garden?
One possibility would be a 10,000-liter (2,642-gallon) retention tank – but this option would be quite expensive. Do you have any other ideas on how to implement this or have you had to solve a similar problem yourselves? I would be very grateful for any practical suggestions. As mentioned, we have to assume that we will never actually need the retention volume, but we still have to present a solution together with the building permit / planning permission application.
If additional information is needed, I am happy to provide more details.
Many thanks in advance for your feedback.
Florian
M
Mottenhausen3 Feb 2019 23:28flopehh schrieb:
to create a retention volume of 9.5 m³ (335 cubic feet) To me, this might be a case for a landscaping contractor: The overflow from a small cistern could lead into a slightly excavated garden area, which the landscaper has sealed with a clay layer beneath the topsoil. For an area of 10 x 10 m (33 x 33 ft), the depth would only need to be about 10 cm (4 inches), for example. Rainwater could then collect there and be discharged through a regulated outlet. How large is the plot? Would an above-ground solution be practical?
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