Stormwater discharge: easement or drainage system?

Hi,


Likely because for whatever reason, other options are unsuitable.

What's wrong with the existing drainage system-does it just discharge onto the ground and are you on the low side of the road or something?


If the development qualifies for a CDC it generally means it is compliant with the local policy so it not really about sidestepping.

See Page 2:

https://www.georgesriver.nsw.gov.au/getmedia/0afdf43b-79e3-481b-a71f-e8014fa61ec6/Complying-Development-Application-Checklist.aspx

and Page 10:

https://www.georgesriver.nsw.gov.au/getmedia/339464df-b0a1-4a87-a6bc-69adeecd6513/Complying-Development-Certificate-Application.aspx




Each site and council is different but if discharge to the council system is reduced via suitable on-site disposal, reuse or detention system they generally look on it favourably-why wouldn't they?



What other possible solutions have you explored and why were they rejected?

If you have not fully explored the options additional info (which DCP applies/suburb, existing site drainage, and topography) would probably result in more useful responses.

Cheers

We're also building in Georges River council area, stormwater design was a bit of a headache but not insurmountable. Our DA was approved in December 2019 so our stormwater design was assessed to the old Kogarah council requirements (post merger, council was using both of the existing Hurstville and Kogarah council requirements depending on where the property was located). However I see that council have recently published a new stormwater management policy covering all areas... https://www.georgesriver.nsw.gov.au/StG ... y-2020.pdf

Can't speak for other council areas, but for Georges River it doesn't matter whether you're CDC or council DA, both have to comply with the same council stormwater management policy.

Regarding an easement through a neighbours land, I can't see that anything in the stormwater management policy says that's required or even preferred. In any case, council can not insist on it and even if they were were stupid enough to do so, all you have to do is get a letter from the neighbour stating that they refuse to allow it.... and then your hydraulics engineer can move on to an alternative design.

Yes, I wouldn't want a pump-out system myself, and in any case, the council area that we and the OP are in strongly discourages them, the words in the old policy said something like.. a pumped system will only be considered after all other systems have been demonstrated to be impractical. Our council area is an older established area (the house we're currently living in is almost 100 years old) and the stormwater infrastructure is quite lacking. The older established houses generally have no documented LPOD and at best have the stormwater discharging to the street kerb, and at worst just have the downpipes discharging to the ground and the water flows overland through neighbours properties.

We've tried previously to obtain easements for stormwater on neighbours properties, for our old property and the new one. In both cases we were unsuccessful despite being on good terms with the neighbours. I don't blame them, I would likely decline a request for an easement on our property, particularly if a practical alternative solution existed.

From my observation, most people doing a new build in our area are able to satisfy council by having the roof water drain to the street kerb via a rainwater tank with a small absorption trench to deal with capturing surface flows, and that's what's been approved for our new build. A copy of the plans are here viewtopic.php?p=1877956#p1877956 Of course, if you're on a steep block on the low side of the street that approach might not be practical, but it seems to work out for most people around here.

Civil Engineer here, and I live in Beverly Hills (under GRC).

GRC allows for charged systems for single dwelling builds, depending on if its possible.

The other DA in the street might be for a dual occupancy, or, a charged system was not possible because:

1. Not enough head (block would have to have a serious gradient)
2. Not enough fall from boundary to kerb (this is required to be at 1% fall)
3. Combination of multi-dwelling (dual occ?) and falling away from the street
4. FL issue on a sloping block.

To my estimation, you will most likely have an easy time with stormwater - so long as you are able to have your Garage RL/FL to be ABOVE your boundary RL, so its worth having your architect consult a Hydraulic Engineer to ensure this is possible, and to keep this as simple and as cheap as possible.

Inbox me if you have any questions/require more info.