How to improve garden drainage along back fence?

[Barbara35]

Hi,

Can you give me any idea of approx costs involved to lay drainage along back fence .

I thought perhaps with agi pipe  fabric on top and blue metal or something the same on the top. approx 40 to 45 feet long.

Regards

Barbara

[JacobZ]

Hi @Barbara35,

A typical French drain, which is what you are describing, is roughly 300mm in diameter.

For a 40–45ft (roughly 14 metres) drainage trench, which is about 300 mm wide and deep, you’ll need roughly 1 cubic metre of drainage material.

These are the materials you will need-

1 x Vinidex 100mm x 20m Socked Slotted Draincoil

2 x GRUNT 1 x 10m Non Woven Geotextile Membrane Drain Mat Fabric

1 x cubic metre drainage gravel. 

Your drain coil and fabric will cost approximately $230. 

Drainage gravel can often be purchased in bulk from your local store's Special Orders desk. You would have to enquire as suppliers are regional and pricing varies, but a cubic metre of drainage gravel is usually somewhere between $100-$140.

All up, you would be looking at around $350 for materials.

If you needed someone to do the labour for you, you would have to get in touch with a landscaper or drainage plumber for a quote.

Let me know what you think, and if you have further questions, please don't hesitate to ask.

Jacob

[Barbara35]

Hi Jacob,

Is drainage gravel the best to use. Do I need something not too fine so that it will drain better?

I thought I would leave the area above the agi pipe open  with geotextile membrane on top on the gravel.

I have contacted a couple of people to give me a quote just thought I would get a rough idea of cost to go by.

If I allow  $350 for materials any idea what labour would cost?

I appreciate your help again Jacob thank you

Kind Regards

Barbara

[Barbara35]

Hi again any suggestions for trades to do this job?

[JacobZ]

Hi @Barbara35,

Drainage gravel is what most drainage plumbers and landscapers would use, but in reality, pretty much any stones that are around 20mm would work.

The best way to make a drain of this nature is to dig the trench, lay the drainage mat into the trench, put in a layer of around 100mm of drainage gravel at the base, put your agi pipe in, then backfill around the sides and 50-100mm above the pipe. Once backfilled, the drainage mat can be folded over the top of the drainage gravel to create a channel that runs through the earth and is isolated from the soil around it. Having the drainage gravel above the pipe will help to protect the agi pipe from being crushed, while still allowing water to drain through it and into the agi pipe, where it will be taken away.

Unfortunately, I couldn't give you a rough estimate on labour costs as prices are incredibly variable. Your best option is to reach out to landscapers or drainage plumbers to get a quote. Check out How to find a tradesperson near you for some guidance.

Let me know if you have any further questions.

Jacob

[Barbara35]

I have had two different opinions from trades

1. Not to use agi pipe because it will let water also come out to use storm water pipe with slits that will only let water in.

2. The drainage mat is not needed under the agi pipe only over it when to metal is added to the top eg. metal agi pipe metal and drainage mat on top then metal on top of that.

 I have had one quote and trades coming next week for more ideas and quotes.

So after I receive them I will have to compare apples with apples and make a decision.

Thanks Jacob

Regards

Barbara

[Barbara35]

Hi Jacob,

I have been on the phone to bunnings eastgardens for over 1 hour on hold and then hung up on an called again and still on hold

I want to find out how much 1 cubic metre of 20 ml blue metal would cost as well as delivery.

After completing this project with the gravel on top I am not going to put soil over it thought it would be better to just leave the gravel as water could drain through better.

Well I am still waiting on the line  to get through hope I don't get cut off this time

Regards

Barbara

[Barbara35]

Hi again Jacob,

It has been suggested that I use flat agi pipe which would collect the surface water better and have an open half round pipe along the top to collect the surface water to travel into the access pipe to stormwater. The problem is more with surface water I have to catch as it flows quickly over and through the garden.

Regards

Barbara

[JacobZ]

Hi @Barbara35,

Apologies for the delay. Have you managed to get in touch with the team at Bunnings Eastgarden?

It sounds like you've been given a variety of different advice, which makes it a bit difficult to compare. 

Do you have any photos of the area where you are planning to install your drainage?

If the problem is more above-ground than below, channel drains tend to be a better option. A combination of the two, like you mentioned in your last comment, might be your best option.

I'll wait for your response to see what you think.

Jacob

[JacobZ]

Hi @Barbara35,

Just checking in to see how you went getting a quote for a cubic metre of blue metal from our Eastgarden warehouse.

If you'd like me to reach out to them to assist, I would be more than happy to do so.

Jacob