Drainage system

"...The system is working now but I was wondering whether it will still work over 2-3 years when the holes on the pipe are clogged...."

Yes, if an appropriate filter material was not placed around the subdrain during installation it will clog. The old-style method was to place a inner layer of coarse aggregate directly surrounding the pipe, then an outer layer of sand around the agregate layer. The size of the sand and rock was determined by a formula based upon the existing soil's characteristics. Presently, geotextiles are wrapped around the pipe as a filter, and are easier to install. The geotextile will last for a very long time, if the properly chosen for the soil conditions.

A company in South Africa, and I'm sure other companies around the world produce geosynthetic liners for all requirements. Check out www.kaytech.co.za

These drains are not maintenance free - in other words, they do not last forever. There is a right way to install them and if this is not done, you will have problems.

"...has installed..."

Clarification please. Installed with the house? Or as a retrofit? Why? Something peculiar about the locale? Doubt that plumbing code would touch this one, as it is not, properly, plumbing.

It was installed after the house was built to solve standing water problem in the yard during heavy rains. Any standing water in the yard that last more than 24 hrs. must be resolved by the builder, this is a one year warranty item.

Sounds like he used a perforated, corrugagted, HDPE pipe for the drain. Fines from the soil matrix, as well as anything else that can get into the pipe will eventually create a mud filled plastic tube.
To get the longest service life out of this type drain we cut a ditch, line it with a filter fabric such as Typar, cover the bottom of the ditch with a couple of inches of 1/2" to 3/4" diameter washed crushed limestone, install the perforated pipe, cover it with more washed crushed limestone, then cover the stone wiht Typar - essentially creating a gravel and pipe filled typar burrito.

The filter fabric keeps the fines and debris from filling the gravel and pipe. Both gravel and pipe provide a path for the water to flow through if the ditch is graded to drain.

Depending on the soil in your area , this will not last forever (High clay or silt content will clog faster than most gravelly or sandy soils), but will give you much better service life than plain pipe.

It is not necessary to use limestone. This is an issue of the physical gradation of the materials used filtering out finer soil particles before they reach the drain. You can use any stable solid gravel. Also, the size of the openings on the drain pipe will determine the size of the particles to use in the filter. You can get pipes with 0.020 inch slots and never need any gravel just a sand or geotextile filter. The larger the opening in the drain, the faster water can enter the drain and flow away. You should determine the drainage area collected by the drains, a representative strom flow, rate at which water can be transmited to the drain, and determine the opening sizes based on this (plus appropriate factor of safety). there are geotextile sleeves youcan place directly over the drain pipe, there is geotextile fabric you can wrap gravel or sand in and place arounf the drian pipe, or you can create a graded drain from sand and gravels. An important consideration is that the more surface of filter exposed to the soil, the longer it will take to clog the filter. For graded filters the materials grade at D85/D15 < 4 to 5, D15/D15> 4 to 5, D50/D50<25. For slotted pipes: D85/Width>1.2. for Circulr Hole Pipes: D85/Hole diameter>1.0. For filter fabric consult a manufacturer like Mirafi (Mirafi is typically used a a geotechnical standar, i.e. Mirafi or equivalent), but as a rough estimate: for clean sands D85/EOS>1, %OA<36, for finer soils EOS< Sieve #70, %OA<10.

The arrangement is sometimes known as a 'land drain'. Experience would indicate that covering similar pipe with another material upon installation, such as a geotextile, will delay its replacement appreciably, though it cannot absolutely prevent it over time.

There are millions of miles of this plastic pipe without covering draining the farmland in the USA. The 4"- 6" stuff I watched them install (pulled) into the ground when I was 8 is still draining the land just fine and I am now 39. Proper fall (slope) in the pipe is the critical factor, not the covering. This same pipe is installed in all types of soil with no problems. The great covering of the pipe idea costs us all extra money now due to codes demanding its use around homes and makes the fiber makers billions... I would use the pipe with covering only if there is no fall in the pipe, as around a basement footing. So, if it was installed properly, no worries. If it wasn't and it's working now, it will probably keep on working due to the fact that the soil around that pipe is now similar to concrete, very firm and compact. The water seeps, weeps, perculates through the ground and into the pipe, it is not rushing in and pulling dirt in behind it. It should be fine.

I as an 8 year old saw many things happening but did not take specific note of all the details. At that stage of my life it was not relevant. At that stage they still put meter lengths of E/W pipe down for sewerage drains with butt joins. They did not factor in that huge trees would grow and their roots would 'rearrange' the drain causing untold damage and expense to have them replaced. Large roots push the pipes up, smaller roots then invade the pipe causing blockages. Things change! We progressed to PVC pipe with PVC sockets (roots still managed to infest) and now use things like plastic welded HDPE pipe for sewerage drains. The pipes installed where you lived may have gone into heavy clay which does not move much with water and is not granular in texture. In developed areas, we build retaining walls, roads, buildings and this all hampers the naural flow of water below ground (in all type of soil). It will eventually find its way out and cause damage to all these man made barriers. Drainage systems (differents systems for different soil types) are installed to reroute this 'problem' water. Most modern systems include geosynthetic liners.

You used a very good word to describe the process - 'perculates'. Have you ever had a cup of perculated or filter coffee that does not have sediment in it? If you did not have that fine filter you would have rough sediment in your cup. Sediment in soil will find its way through. One needs to remove larger sediment particals as much as possible to avoid blocking the drainage holes in the pipe. A drain in bad soil will have a longer life span if it is installed with a liner. The positioning of the liner is critical.

good points here are:

Trees or roots in general are bad for drains, and maintenance should be considered in design.

and sufficient slope to maintain flow velocities in the pipe will help keep it flushed of sediment deposits.

You however do not need a liner for the pipe. This will just clog fairly fast. A filter with the largest possible surface contact to the draining soil and proper gradation is best. In truth you actually can design a drain without any pipe, just graded materials like earthen dams would utilize for chimney and blanket drains. Also, much like a coffee filter, the more effectively used surface area to the filter, the greater the total volume of fluid that will be transmited.

The correct gradient is paramount and grass roots the worst especially couch grass.

It is also possible to use prefabricated drain system which has special filter fabric resistant to clogging. There are also prefabricated findrains (actually used for road edge drainage ) could be used for area drainage. http://geosynthetic.blogspot.com/search/label/Drainage

You may have some information in above blog.