All Topics / Help Needed! / New development but no storm water? HELP

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  • Profile photo of BenBen
    Participant
    @albanga
    Join Date: 2014
    Post Count: 54

    Hey All,

    I am currently in the process of developing a dwelling to the rear of my PPOR and have just discovered we have no storm water. My block slopes to the rear with about a fairly decent slope (roughly 5m from curb)

    I have spoken with Council who confirmed this and also my neighbor who actually showed me his storm water pipe running into the rear neighbors backyard!!!!!! I was still not 100% convinced though, I mean the land was subdivided around 70 years ago but given all the the sloping blocks surely there should have been storm water installed!

    So on the weekend I took to my backyard with a shovel and started to locate where all the pipes were running. After several holes I found myself in the easement where sure enough I found the end of the storm water pipes which were buried around 30cm under the soil and open which meant the water would pretty much run directly into my neighbors backyard! (same neigbor with a big block) The interesting thing though is the soil was not wet? The block is in Melbourne and we have had a fair whack of rain so i would have expected it to be very wet but it wasn’t?

    I am not sure what to make of that? I put my hand into the pipe and it was compacted with soil but perhaps given the pipe is old ceramic then it would have leaked through the joins throughout.

    So anyway I have now been advised I will need a pump system engineered to push the water back up the hill to the only available “authorised” council storm water at the curb. I have not received an actual quote but I have been advised to expect anything from 15-30k!!!

    So before I do that I just wanted to throw it out there to see if anyone had any suggestions at all? Has anyone dealt with this? I did read someone had a similar issue and actually elevated the slab so the water could run downhill so no need for a pump. I unfortunately do not have this luxury due to the dwelling being at the rear and the size of the slope.

    Thanks in advance :)

    Profile photo of BennyBenny
    Moderator
    @benny
    Join Date: 2002
    Post Count: 1,416

    Hi Ben,
    Wow – sounds like a problem… and, no, I don’t think i have the whole answer, but wanted to share a couple of thoughts :-

    1. The home we bought 30 years ago had a similar thing. No slopes to speak of, but the thing that rocked me was that downpipes were ALLOWED to “splash-feed” onto the ground rather than being piped away (according to laws that existed back then). But then, I found the builder HAD installed underground pipes from our down-pipes – the underground pipes ran into the property next door – and stopped….

    2. I don’t know how much rainfall you might get (especially when compounded by run-off down that slope), but maybe there is a chance of creating a “sink-hole” i.e. get in a bobcat and cut a big wide trench across your property, fill it with rubble, and allow the water to dissipate underground to surrounding soils. You would obviously need to check a number of things (via a hydrologist??) like :-

    a. re your comment “The interesting thing though is the soil was not wet?” – does that mean the rain is soaked up by surrounding soils BEFORE it even gets to a depth of 30cm? In which case IS there any problem? Could it be that the existing easement and drain is more than sufficient as is?
    b. do “problems created by past (inadequate but acceptable) laws” receive any leniency in rectifying the problem today?
    c. what does your “neighbour with the big block” have to say? If they have never noticed a problem with your run-off, is there one?
    d. what cubic capacity would the sink-hole need to be, how deep, and do you have adequate space to create it on your property?

    I have only a layman’s knowledge of water and its effects, but I recall hearing that heavy rains become a problem AFTER the ground surface soils have saturated – after that, any excess “runs off” without being absorbed. And of course, a steeper slope will have run-off occuring more quickly than a gentle slope (with the latter, water has more time to “sink into the gorund”).

    Could some kind of action taken with your soil make it more absorbent to minimise any run-off (assuming you have grassed areas – no good if all concreted) – by action, I mean using a cultivator device of some kind to allow water to “sink” rather than running off. Or perhaps utilise products that could be sprinkled ON your grass (e.g. like those capsules that absorb water – used when planting to assure moisture to the new plants).

    Hmm, maybe not much actual knowledge there, Ben – but hopefully some ideas that “might” work – good luck with it,

    Benny

    • This reply was modified 7 years, 6 months ago by Profile photo of Benny Benny.
    Profile photo of BenBen
    Participant
    @albanga
    Join Date: 2014
    Post Count: 54

    Hi Ben,
    Thanks for your very detailed response!

    Yeah it is quite crazy this practice was allowed. Our down pipes run into the ground and I did follow them to the end of the property where they just go off into the soil which is basically right up against the neighbors fence. The funny thing though is I spoke to my left neighbor who also shares his back fence with the same property as mine (large property) and his pipes visibly run into the rear property!!! You can actually see the pipe!

    The property is in Melbourne’s North West so we get a little bit of rain but I have never experienced flooding before. I actually spoke to council about your suggestion and another someone suggested in regards to a rubble pit. They basically said this practice is not allowed and you need to connect to a council approved termination point which for me is to the curb, hence the need for pumps up my hill, OR there is a termination point on my street but 187 meters from my property, through the easement of 13 neighbors. The guy from council said you would need to get everyone to agree to running the storm water and that the cost would sit with me as the developer.

    In regards to your questions:
    a) I spoke to my dad about this who was a civil engineer and specialised in pipes and explained how the ceramic pipes will release the water at the joints so it would appear the water may be releasing into the soil before even making it to the end of the pipe. So as far as im concerned this is adequate but the problem is not with the current property, it is with the new dwelling and unfortunately I am not permitted to do this. Existing dwellings are not required to change storm water as this is how it was back in the day but new properties must conform to the new building codes and terminate at a council authorised storm water termination point.

    b)It would appear they do not! I would have thought council would have to take some responsibility for this but the problem is then who pays for it? I am sure people in the neighborhood with perfectly good storm water don’t want their rates going so someone can profit from a development.

    c) They have not complained because as i said, the water is not even making it that far. Again though, the problem is not with the existing storm water, its that the new one cannot use that method and they are saying need a pump.

    Thanks for your great suggestions and feedback Benny. It is definitely an eye opener as to how things are done, and how willing council are to assist in rectifying these issues!

    Profile photo of hanoixuahanoixua
    Participant
    @hanoixua
    Join Date: 2007
    Post Count: 19

    Your new house will create more storm water run off from the site. It is new policy that you need to divert it back to the kerb, unless you can arrange easement with your neighbour to get stormwater through. It is also very expensive exercise. Your slope is too great 5m, a sealed system will not work unless you have double storey. Pump system is highly likely your only viable option.

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