Shallow roots

Elizabeth Winstanley

Help please. I need to plant a hedge/barrier to prevent vehicles being driven over sewage/water pipes which are very close to the surface. Obviously they would need to have a fairly non invasive root system. They would be planted approx  3 ft away from pipes.  Soil is mixture of sand and clay.
Other criteria -  About 4ft in height to be visible to drivers and the most difficult of all providing year round interest. A mixture of evergreen and deciduous is workable.The position is East facing but not exposed and it gets sun for most of the day in summer,  less in winter as the whole site is surrounded by mature trees.
It's a tall order but I hope you knowledgeable people out there can help.

madpenguin

Could you post a photo of the area?
It might give us more of an idea what to suggest 

Fairygirl

At a previous house, our pipes led out from the septic tank, and we had privet and hawthorn  hedging [already there ] which certainly never caused a problem. We had a couple of mature trees there too - a holly and a cherry. 
However, the pipes would have had far more cover than yours sound. Is there any way you can build up the ground a bit too?
The photo that @madpenguin suggests would be helpful though, to give us a better idea of the site you're dealing with. 

Dovefromabove

I think a lot may depend on whether the pipes are modern continuous plastic piping or the older short lengths of terra-cotta type of pipes ... the latter are particularly susceptible to roots invading their joints. 

Elizabeth Winstanley

Pipes are modern plastic so section to be protected doesn't have any immediate joints. Unfortunately they can't be buried any deeper and have actually had to be raised to allow for better flow and prevent blockages. Topographical problems!

Fairygirl

Would it be easier to have a small fence?
It's hard to visualise the area without a pic though.

Obelixx

I'd put up a low fence altho round here they use large chunks of rock as a boundary/edge marker on verges and drives.  That stops cars overstepping their boundaries very effectively.

Elizabeth Winstanley

Fence not an option I'm afraid and a photo would only show a grassy bank sloping down to an, at present, filled in trench in a flat grassed  camping area. Vehicles come round the corner of the slope  and unless  prevented would run across the pipes. They just need to be kept further away from the pipeline.
 A hedge is more in keeping with the nature of the area and one consisting of suitable flowering shrubs could give year round interest. A variegated Griselinia has been suggested as being suitable any thoughts on this?

Dovefromabove

Think I’d give consideration to a hedge of Rosa rugosa ... the roots shouldn’t be a problem, height can be easily controlled, not fussy about soil, easy to establish,  scented pink or white blooms, colorful hips autumn into winter so attractive most of the year and wildlife-friendly. 

Loxley

Is it a natural area? Variegated griselinia sounds like it would look a bit alien and suburban. It's not amazingly hardy either so unless you're in the south west, in a city, or near the coast I'd think about something else.

Loxley

Could you not do something like this 

Or this


And then let the area behind go wild?