DA possibility? - LMR2 607m2 15m+ frontage, minor overland flooding

Hi all,

I am considering the purchase of a 600m2 block with 15m2+ frontage zoned LMR2 in Brisbane. The issue is that it has overland flow path flooding impact at the front of the block only (including most of the street), but the rest of the block is flood free (according to BCC report). I have seen developments closeby where 4 small townhouses have been approved (or at a minimum a subdivision into 2 blocks) where there is no flood problems....what are the chances of doing the same on this block given a small overland flow impact?


Many thanks!

 

Obviously get town planning advice, and there will be some additional costs involved in the build, but its do-able.

 

easy, you can 'stalk' the nearby site that had approval. learn from their town planning advice and approval...the report should have the TP contact details and perhaps use the same Planner that got the nearby approval..a few chat to that Planner is often free advise..

you can PM me the nearby address, and see if I can get that Town Planning report for you

 

perfect, thanks guys - I am waiting to hear back from a planner, just wanted to throw it out there.

I have obtained the planning reports for the nearby developments through council but thank you for the offer

appreciate the responses so far

cheers

 

Get addresses of similar sites in the area and go to

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Punch in address and search. They will have relevant docs for the DA in there. Overland flow would generally be assessed by a hydraulic engineer for recommendations of what additional stormwater works are needed to reduce impact. Also need to be weary of the flow path and potential impacts downstream to other properties. Standard condition on DA is that the development cannot impact properties downstream ie you cant just build a spoon drain and direct all the water on to the next property.

 

Overland Flow can be more problematic than flooding. You may need to build on an elevated platform. Also note that BCC has gotten very strict on their interpretation of what constitutes flood free access to a site.

 

It is only an issue if you intend to build within the actual overland flow path. Check the interactive mapping for the site and add the overland flow overlay - City Plan 2014 Interactive Mapping

If you do build within the overland path then you would need a hydraulics engineer's overland flow assessment which can cost a few thousand. They will need to advise if you can build a slab on ground construction or must be high up on stumps.

Otherwise if the overland flow path doesn't touch where you want to build then it is not an issue.

 

I'd engage a town planner. Some advice is very specific in nature and my first stop would be a good town planner. Regardless of what anyone says here you will still need to engage one for specific advice

 

Thanks all, appreciate the responses and discussion! I most definitely will engage a planner to assist when I’m good to go, just love to hear others’ thoughts.
I also had the the developer behind us wishing to link to the storm water and sewer out the front of our block via 150mm stormwater pipe inside my boundary (no easement required under BCC regs). However if I do this and plan to build a few towns houses or subdivide, I might have to upgrade the pipes to 165mm which will require easement (1.5m) to protect BCC infrastructure ...thoughts:
1. Allow with due compensation (need to do my analysis on land value as we have LMR2 in Camp Hill...any ideas on rate/m2?)
2. Allow with or without compensation but ensure he puts 165mm infrastructure in place now for my future development, either subdivide or townhouses)
3. Don’t allow and keep my options open for my own future development

Cheers

Edit: Note this won’t stop his development as he can run hydraulics on his site to pump storm water and sewer uphill. Maybe he missed this in his DD of his site?

 

Hard to advise with out much detail, but I guess I would be inclined to permit him on the basis that he puts in the 165 pipe (making doubly sure this is the max that could be required on your site - I recently had to put in a 250 mm upstream stormwater connection to allow for max development of the site behind) and as long it goes down one of the boundaries it probably isn't any big deal provided you can build over it if you need to. Should save you dollars as you won't have to put in a pipe and what goes around comes around?

 

Depends on how nice you want to be. On-site detention and pump out facility is not cheap option and adds considerable ongoing maintenance costs (higher than usual body corporate fees). You could probably get the rear developer to install the pipe, provide a stub for your development and pay compensation ($20 - 30k). However, just keep in mind, if you develop your site before the guy at the rear, Council will condition that you install an upstream stormwater connection for this property (at your cost) so you probably don't want to alert the rear neighbour to the fact that you plan on developing your site in the near future.

With regards to the overland flow issue, there is not much that your town planner will be able to add as overland flow is quite different to Brisbane River/Creek/Waterway Flooding so they can't just check the flood levels on Council's floodwise property report. You really need to engage a hydraulic engineer to model the catchment and advise on the flood depth and velocity of the overland flow. As RPI mentioned, flood free access is potentially going to be an issue for you given the overland flow path runs through the front of the site. I would engage an engineer as part of your due diligence as there is a risk that you won't be able to develop the site if you can't achieve flood free access. From memory, if the overland flow path is less than 300mm and less than 0.6m/s in velocity, you can generally get away with it. I also wouldn't assume that because someone else in the street got approval that you can also do it, as overland flow can be site specific, plus Council's requirements change over time. Under City Plan 2014, Council have become a lot stricter when it comes to achieving flood free access, particularly where involving localised flooding (overland flow).

Cheers,
Liam

Edit: I just noticed that the upstream developer wants to connect into the sewer at the front of your property as well. What's their other alternative for this if you say no? I assume their sewer pipe is located in the street (or front of their property), in which case they will need to fill the rear of their site to get sewer to gravity feed to the sewer pipe. This would also be a fairly expensive exercise depending on the slope.