Browse Forums Landscape & Garden Design 1 Aug 21, 2017 1:10 pm Hi guys
I Hope I make some sense here in my explanation of what I'm trying to do. So, what I’m doing is fixing water issues we had where water was flooding our pergola because of incorrectly installed agi drainage pipes. At most areas of the garden bed most of the pipes were almost exposed and some areas were not even close to the footings. I have removed huge load of clay and dirt from behind the retainer wall, nearly 2x8 cubic bins of clay and dirt and probably expecting more. In front of the retainer wall I'm putting a concrete path as you can see from the dirt path, (hopefully it's a little clear in pic 2). The area has been left this way for some time now so it's a bit of a mess. I did a lot of the work in the rain, I know was a silly thing to do but was easy to work with the clay back then, now its rock hard. Behind the retainer wall there is obviously a prepared trench I dug up with the aid of a mini excavator and heavy shovelling and did my best to compact the clay to create a reasonable fall. There is a storm water drain opposite the retainer wall (pic 3), it is messed up now and can’t really see it but it will be where my daughters pink bike is obviously we are fixing that area too. The storm water drain here has the proper downstream fall to end up on the road. I have dug up the clay just below the footing of the retainer walls and made it wide enough (probably about 600mill or so wide at some areas) so that I can lay about 50mill of blue metal and then either have double agi pipes or just a single agi or maybe use the geotextile fabric method where you encase the blue metal and pipes method. Would be great to get your opinion. I have core drilled 3x 150 mill holes at the base of the retainer wall which might be over kill but it’s what I want, just picture 3 holes and at the base of that wall widely spaced apart, (pic 1 and 2 you can’t really see it because it’s below the dirt there) that is where the three outlets will be. The agi pipe will come out of there into a pvc pipe across the grass (pic 3) and into a storm water pit somewhere. I chose pvc instead of agi because I didn't really have any issues with water pooling on my grass. There will be another exit under the pergola obviously away from the pergola to the side of the house where there is another storm water drain. I also will be waterproofing the back side of the retainer wall and re rendering. I honestly think I’m not going to backfill it with soil probably just frigin rocks as I'm traumatised from the mess and bloody scared I'll have to dig out the agi again soon. I'll probably put pot plants not sure. It will probably be better drainage anyway. I'll probably pay someone to lay concrete and install the drainage channels, I figure it will be difficult for me to do. I will also be running drain channels for the concrete where needed. Your opinions: 1.Where would I install the pit do I install it close to the storm water drain? 2. Should I install 3 separate pits where I will be laying the concrete path where my 3 agi pipes exit. Or is it even necessary is it overkill, maybe just 1 maybe or maybe none, and If i need a needed a pit where would it be best located? 3. How do you determine how much water drainage is acceptable to one storm water drain, l(worried that im putting too much down one pipe) 4. Am i allowed to run another outlet to the street for extra drainage or is there special requirements. We get a heap load of water flooding. I know that there are going to be times where flooding is inevitable with the downfalls we get in Sydney but i want to do my best to get it flowing better. 5. Which method agi pipe, do I double agi side by side? If so how do I join them? Do I single agi or do I geotextile method where i encase the blue metal and agi together. P.S I have attached a rough computer layout of roughly how it should look to give you an idea what im doing. (Pic 4) Cheers guys hopefully I haven’t confused you too much. Let me know your thoughts Pic 1Retainer wall view facing pergola Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Pic 2Retainer wall view away from pergola Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Pic 3Opposite the retainer wall view Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Pic 4Computer image of what I'm trying to achieve Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Re: Retaining wall drainage, plumbing concerns. 2Aug 21, 2017 9:03 pm Hey there. Why are you putting drainage in front of the wall? That's the absolute opposite of what you should be doing. The back part of your wall should drain any excessive water soaking within the garden bed to alleviate any load or pressure due to the pooling of water. You have mentioned that you are putting a few toe drains through the wall but isnt this also pointless as the wall will now weep water, and also stain your future concrete path? If you have access behind the wall, do both; waterproof the back install one or two ag-pipes, backfill with aggregate and top with some soil. I just posted an update on my thread with detail on the required drainage for my engineered retaining walls if you need further information. Just make sure your ag lines go somewhere, ie plumb them into one of the pits your planning to use for surface runoff on the concrete path. Re: Retaining wall drainage, plumbing concerns. 3Aug 22, 2017 6:52 am Just back to the basics AGI pipes are for sub soil drainage and you should have them behind the wall, your pit should be at the lowest point and if you are getting flooding then you need surface spoon drains. It is unlikely you will get a lot of water in the sub soil drains but more likely you will get a lot of surface water run off. Pay particular attention to gettingg rid of surface water fast. Foremost Building Expert in Australia,assisting with building problems/disputes, building stage inspections,pre-contract review advice for peace of mind 200 blogs http://www.buildingexpert.net.au/blog Re: Retaining wall drainage, plumbing concerns. 5Aug 22, 2017 7:10 am building-expert Just back to the basics AGI pipes are for sub soil drainage and you should have them behind the wall, your pit should be at the lowest point and if you are getting flooding then you need surface spoon drains. It is unlikely you will get a lot of water in the sub soil drains but more likely you will get a lot of surface water run off. Pay particular attention to gettingg rid of surface water fast. Appreciate your response this is all good feedback for me. Definitely i'm putting drainage behind not in front . When you say the pit at the lowest point, i'm installing the pits close to the retainer wall to ease the pressure a bit on my storm water drains, the agi pipe behind the wall will tee connect to three pits in front of the retainer wall which will also act as a good surface drain, do you think its not a good idea, you think i should be putting the pit further away the retainer wall, because the lowest point would be in the corner where the garage door is? The surface water yes indeed i will be putting drain channels where the concrete path meets the retainer wall, that way if get a heap load will be less chance of the fall from the new concrete path flooding into my pergola. Unless i change the fall of of the concrete path, Cheers Re: Retaining wall drainage, plumbing concerns. 6Aug 22, 2017 7:11 am SteveMc Hey there. Why are you putting drainage in front of the wall? That's the absolute opposite of what you should be doing. The back part of your wall should drain any excessive water soaking within the garden bed to alleviate any load or pressure due to the pooling of water. You have mentioned that you are putting a few toe drains through the wall but isnt this also pointless as the wall will now weep water, and also stain your future concrete path? If you have access behind the wall, do both; waterproof the back install one or two ag-pipes, backfill with aggregate and top with some soil. I just posted an update on my thread with detail on the required drainage for my engineered retaining walls if you need further information. Just make sure your ag lines go somewhere, ie plumb them into one of the pits your planning to use for surface runoff on the concrete path. Sorry if i did not make it clear, I have dug up behind the retainer wall not in front to put agi drainage, the dirt dug up in front is for my concrete path. I'm not sure where i mentioned this but i am definitely putting agi behind mate. Thanks for your response i appreciate it. "You have mentioned that you are putting a few toe drains through the wall but isnt this also pointless as the wall will now weep water, and also stain your future concrete path?" Sorry im not familiar with the "toe drain" term? what part of the post you referring to? Re: Retaining wall drainage, plumbing concerns. 7Aug 22, 2017 9:31 am aspire029 "You have mentioned that you are putting a few toe drains through the wall but isnt this also pointless as the wall will now weep water, and also stain your future concrete path?" Sorry im not familiar with the "toe drain" term? what part of the post you referring to? The core drilled sections through the wall will act like toe-drain. A toe-drain is a simple exposed drainage line to allow water to drain away and weep. Unless you plan on sealing these up after putting your PVC in, they will be areas that will weep water into the surrounding ground (ie. around the path/wall area of the slab). You only need one drain and then only connect it to the lowest point in your yard. Re: Retaining wall drainage, plumbing concerns. 8Aug 22, 2017 1:33 pm SteveMc aspire029 "You have mentioned that you are putting a few toe drains through the wall but isnt this also pointless as the wall will now weep water, and also stain your future concrete path?" Sorry im not familiar with the "toe drain" term? what part of the post you referring to? The core drilled sections through the wall will act like toe-drain. A toe-drain is a simple exposed drainage line to allow water to drain away and weep. Unless you plan on sealing these up after putting your PVC in, they will be areas that will weep water into the surrounding ground (ie. around the path/wall area of the slab). You only need one drain and then only connect it to the lowest point in your yard. These core drilled holes are core drilled to where ever the agi pipes will Tee off into which is pretty much close to the footing. Behind that area will be water proofed, i see what your saying though ill make sure its waterproofed and sealed around the pipes entering the holes from the back as well ill put one of those flanges or seals to seal any gaps around the pipes and then water proof it. I need this otherwise i wont have an exit point for my agi and water just fills up and sits there with no where to go. So i have made three exit points that will exit out . I have already drilled out 3 points, will it matter that ill have 3 drain pits on that footpath they wont be overly huge? then ill connect it to the lowest point in the yard. I know it might be overkill but ive already drilled them out. Thanks again Thanks for all replies. I just noticed now the pictures I added to post right on top of page were wrong. I attached pictures showing "current" and my "suggested" floor… 9 14609 Regardless of wall hung toilet or floor pan toilet your feet will be right on drain, seems to me the waste should not be in that location given the design. Also are you… 6 7020 Thank you again Simeon.. I will call my certifier for that. Have a good day 4 5105 |