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#1 picusld

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Posted 09 February 2011 - 03:40 PM

In PA I am having a guideline enforced on me which states that the maximum drainage area to bmp may not be greater than an 8;1 ratio.

So I if have a 1 ac footprint basin, I can have a max of 8 ac contributing to it.

Is anyone aware of anything similar being implemented around the country which may allow more area or some sort of formula that may justify a greater area to flow to a BMP?

Any help would be appreciated.

#2 VTEnviro

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Posted 09 February 2011 - 04:01 PM

I deal quite a bit with stormwater and have not heard of something like this. Are they trying to prevent flooding in some massive storm or massively changing existing hydrology around so it all drains to one point?

Can you do something like a diversionary swale where the water hits your site? You typically don't have to treat off-site stormwater and this way you won't need to design something excessively large to accomodate the volume of the off-site contributory area.

Another possibility is grading your site so you end up with a number of small 'pocket pools' (no not that kind of pocket pool you sickos!) that treat a couple acres here and there rather than creating the 6th great lake to handle your whole site.

#3 picusld

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Posted 09 February 2011 - 04:21 PM

QUOTE (VTEnviro @ Feb 9 2011, 01:01 PM) <{POST_SNAPBACK}>
I deal quite a bit with stormwater and have not heard of something like this. Are they trying to prevent flooding in some massive storm or massively changing existing hydrology around so it all drains to one point?

Can you do something like a diversionary swale where the water hits your site? You typically don't have to treat off-site stormwater and this way you won't need to design something excessively large to accomodate the volume of the off-site contributory area.

Another possibility is grading your site so you end up with a number of small 'pocket pools' (no not that kind of pocket pool you sickos!) that treat a couple acres here and there rather than creating the 6th great lake to handle your whole site.


The public reason is that they want to limit the amount of contributing water to a BMP to avoid BMP failure. The non public opinion (IMO) is that it is a backdoor way of limitting the amount of land that can be developed on a property since 1/8 (or more) will always have to be some sort of volume control BMP which due to perpetual easement requirements enforced under the Clean Water Act will be deed restricted forever.

In my case I have a 100 ac residential site where 16 ac of it goes to a main basin which has about a 1 ac footprint. I essentially have to come up with another acres worth of volume control BMPs within the 16 ac contributing area without significantly changing the layout (since it was a result of litigation).

I have already proposed a number of onlot seepage pits/drywells to try and come up the acre but 43,560 sf is alot of seepage pits and maintenance is going to fall on the individual lot owner (where the pit is proposed)

This is on top of the requirement that the pits be deed restricted with a perpetual right to enter agreement between the property owner and the DEP.

#4 ROBIAMEIT

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Posted 11 March 2011 - 02:01 AM

QUOTE (picusld @ Feb 9 2011, 05:21 PM) <{POST_SNAPBACK}>
QUOTE (VTEnviro @ Feb 9 2011, 01:01 PM) <{POST_SNAPBACK}>
I deal quite a bit with stormwater and have not heard of something like this. Are they trying to prevent flooding in some massive storm or massively changing existing hydrology around so it all drains to one point?

Can you do something like a diversionary swale where the water hits your site? You typically don't have to treat off-site stormwater and this way you won't need to design something excessively large to accomodate the volume of the off-site contributory area.

Another possibility is grading your site so you end up with a number of small 'pocket pools' (no not that kind of pocket pool you sickos!) that treat a couple acres here and there rather than creating the 6th great lake to handle your whole site.


The public reason is that they want to limit the amount of contributing water to a BMP to avoid BMP failure. The non public opinion (IMO) is that it is a backdoor way of limitting the amount of land that can be developed on a property since 1/8 (or more) will always have to be some sort of volume control BMP which due to perpetual easement requirements enforced under the Clean Water Act will be deed restricted forever.

In my case I have a 100 ac residential site where 16 ac of it goes to a main basin which has about a 1 ac footprint. I essentially have to come up with another acres worth of volume control BMPs within the 16 ac contributing area without significantly changing the layout (since it was a result of litigation).

I have already proposed a number of onlot seepage pits/drywells to try and come up the acre but 43,560 sf is alot of seepage pits and maintenance is going to fall on the individual lot owner (where the pit is proposed)

This is on top of the requirement that the pits be deed restricted with a perpetual right to enter agreement between the property owner and the DEP.


Seems to me that 16 acres contributing to 1 acre of treatment is a little excessive. I would think that even 8 acres to 1 acre is a bit heavy

#5 Risk

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Posted 02 May 2011 - 06:04 PM

QUOTE (ROBIAMEIT @ Mar 10 2011, 10:01 PM) <{POST_SNAPBACK}>
QUOTE (picusld @ Feb 9 2011, 05:21 PM) <{POST_SNAPBACK}>
QUOTE (VTEnviro @ Feb 9 2011, 01:01 PM) <{POST_SNAPBACK}>
I deal quite a bit with stormwater and have not heard of something like this. Are they trying to prevent flooding in some massive storm or massively changing existing hydrology around so it all drains to one point?

Can you do something like a diversionary swale where the water hits your site? You typically don't have to treat off-site stormwater and this way you won't need to design something excessively large to accomodate the volume of the off-site contributory area.

Another possibility is grading your site so you end up with a number of small 'pocket pools' (no not that kind of pocket pool you sickos!) that treat a couple acres here and there rather than creating the 6th great lake to handle your whole site.


The public reason is that they want to limit the amount of contributing water to a BMP to avoid BMP failure. The non public opinion (IMO) is that it is a backdoor way of limitting the amount of land that can be developed on a property since 1/8 (or more) will always have to be some sort of volume control BMP which due to perpetual easement requirements enforced under the Clean Water Act will be deed restricted forever.

In my case I have a 100 ac residential site where 16 ac of it goes to a main basin which has about a 1 ac footprint. I essentially have to come up with another acres worth of volume control BMPs within the 16 ac contributing area without significantly changing the layout (since it was a result of litigation).

I have already proposed a number of onlot seepage pits/drywells to try and come up the acre but 43,560 sf is alot of seepage pits and maintenance is going to fall on the individual lot owner (where the pit is proposed)

This is on top of the requirement that the pits be deed restricted with a perpetual right to enter agreement between the property owner and the DEP.


Seems to me that 16 acres contributing to 1 acre of treatment is a little excessive. I would think that even 8 acres to 1 acre is a bit heavy


Side-lot and rear-lot swales?

#6 picusld

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Posted 03 May 2011 - 11:17 AM

Nevermind to all. Found what I was looking for.




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