Water level rise from pre to post
Water level rise from pre to post
(OP)
Hello,
I have a project proposing an addition to an existing dwelling. The addition is so big it is causing a minor increase in peak flow in the post condition compared to the pre. An increase here in New Castle County, DE means the home owner needs to build a SWM system. I expanded my drainage are as much as I can.
The reviewer said he will accept it as "no increase" If the water surface elevation in the pre does not increase in the post by more the 0.05-ft. Problem is I have no swale in the pre condition to compare my swale in the post! Lol. Is there a calculation that would allow me to check sheet flow depth at the analysis point?
Thank you!
I have a project proposing an addition to an existing dwelling. The addition is so big it is causing a minor increase in peak flow in the post condition compared to the pre. An increase here in New Castle County, DE means the home owner needs to build a SWM system. I expanded my drainage are as much as I can.
The reviewer said he will accept it as "no increase" If the water surface elevation in the pre does not increase in the post by more the 0.05-ft. Problem is I have no swale in the pre condition to compare my swale in the post! Lol. Is there a calculation that would allow me to check sheet flow depth at the analysis point?
Thank you!
RE: Water level rise from pre to post
RE: Water level rise from pre to post
Curious:
Does this not qualify for an Standard Plan? (Residential construction less than 1.0 acre disturbed) or an exemption? (less than 5,000 feet of disturbance)
Otherwise:
If there is no channel on site - one would probably need to establish a downstream analysis point where there is channelized flow (swale, ditch, closed drainage system). This should be a point of agreement with the reviewer at a pre-application meeting.
RE: Water level rise from pre to post
Explain this approach in the report and let the reviewer comment otherwise.
RE: Water level rise from pre to post
RE: Water level rise from pre to post
RE: Water level rise from pre to post