Gravel pit - Drainage issue

[mickavalon]

Visited a prospective clients Garden this week, and they've asked us to deal with a slight problem with their Rear Garden.
The Garden is approx 13x14 mts, and is filled with 200-270mm of 20mm gravel, and what appears to be a Drainage sump, complete with Pump and pipe-work in and out to mains.
They say that in heavy periods of rain the water shows itself at surface level, but drains away quickly once the pumps turned on, so I'm guessing the drainage system installed by the previous owners works quite well, without me digging out to investigate.
The site is Green belt and has a history of high water, but the previous owners decided that filling the area with 8-9" of gravel was his best resolution to the problem!! The clients want a Lawn, so I'm proposing laying over with a Geo Fabric, and importing 150mm of Top soil and then Lawn, thinking that the Gravel will act as a storage area for the problem water, but the weight of the soil/lawn will stabalise the area. Anyone see any flaws in this plan??

[local patios and driveway]

sounds like a plan but will the gravel not move around underneath? im not sure.

[r896neo]

Thats a whole heap of soil to import... Whilst i'm not overly keen on them this may be a prime case for an artificial lawn. I would say even with a drought tolerant seed mixture keeping it from drying out may be a problem.

[local patios and driveway]

seen an artificial lawn recently thats two years old, looks terrible, weeds growing on it and everything. nope dont like em

[mickavalon]

I know r896neo mate( I don't know your real name sorry), but the option is either taking out over 75 tonnes of gravel and putting back, what I'm not sure, or trying to deal with it on site. Even if we did put in an artificial lawn we'd still have to move approx 30 ton of aggregates, say 25 ton type 1 and 11 ton of sharp as against approx 30 ton of top soil for a lawn. Problem with plastic grass is it costs avarage of £15+ per m2, as against £3 a roll of Lawn, and it looks crap. I will speak to the client about his budget and get some advice from a few Turf suppliers.
Their main concern is the Wife is suffering gradual loss of mobility, so this is limiting her access to the Garden.

[r896neo]

It will be almost impossible to keep moisture or nutrients in the soil. The problem with laying turf is you have very limited choice over the seed mix.

Last year i tried out a low maintenance seed mix for a garden by the sea which is on pure sand and drains almost instantly. It only needs cut once a month and is very drought tolerant because it's all deep rooting fescue's.

It was a horror show to get established and looked terrible for 2 months cause it grows so slow and needed 2 weed treatments early on. Now it's established it works well and stays quite green compared to the straw they had before.

Why the MOT? the gravel is never going to compact any more so surely artificial grass could be layed on a geotextile and then maybe 75mm of grit blinding as a sort of blinding course?

Its Simon by the way.

[mickavalon]

your right Simon, Type 1 not relly needed, just get used to specifying it for nearly everything we do!!
The clients also interested in a bit of wild meadow, but he's really not keen on the artificial.
The water table at the moment can rise to the top of the present Gravel, but drains quite quickly if they turn on the pump.
The previous owner has excavated down towards the water, where-as the neighbours, whose gardens are at the "normal" level, only seem to suffer occasional problems, but have relativley healthy looking lawns. So the previous guy, in trying to prevent flooding may have given the effect of a sump for all the surrounding land to drain into. I'll look carefully at a suitable specification for the lawn, and he may have to add nutrients to the soil and regularly afterwards, but wether to go for drought tolerant or flood prone is another headache. I may have a go with the artificial again.

[mickavalon]

I think I'm gonna have to go the Plastic route after all.POP to do but hurts the sole to look at!!:(

[mickavalon]

Soul I mean.:p