To wrap or not to wrap? - Drain cloth all round or only on top?

[BC4ME]

Greetings from sunny British Columbia - usually rainy, but not so far this year!

Am redoing my perimeter drains around the house due to flooding. Am undecided whether to put the drain cloth/filter fabric all round the pipe or only top.

My concern is that the 'fines' will be caught by the cloth and accumulate there, making an abrupt barrier that will become more and more impermeable, instead of dispersing themselves among the drain rock (3/4" pebble rock) and even migrating into the perforated pipe and being carried away by the flow.

I can see the logic of cloth on top of the rock, but how much lateral movement of fine sediment is there likely to be, and with the cloth on top, I presume that the water will be able to migrate down around the sides of the cloth should it become clogged with 'fines' and find its way into the drains.

I hope this makes sense and would welcome any comments. I've started with the full wrap, but the more I look at it, the less I like it.

The soil is hard pan with about a foot of topsoil on top. There is a heavy flow of ground and even surface water during the winter, due to the slope of the land surrounding our property. The drains depth varies from 2 to 6 feet. I am considering using dimpled membrane on the side facing the slope of the land to improve flow down to the drains, which are at about 2.5 ft depth.

[seanandruby]

why dont you buy the filter drain that is already sleeved with membrane? its a bit more expensive but weigh that up with the time spent wrapping your own should balance it out. or dig your trench, put in fabric, stone, pipe, cover in stone then fold fabric over enveloping the whole pipe run.

[Tony McC]

Full wrap, everytime. It prevents sediment accumulating within the drain system proper. See Land Drain page.

Incidentally, I think we've been sent your rain by mistake. It's not stopped here for the past four days. Do you want it back?

[Mike_Missourah]

Since nature and the crankiness of the Meramec River have had me learning and relearning quite a bit about the nature of water (persistent, implacable, perverse, etc), the post of BC4ME (12/8/08) caught my eye as did the comments of the “Site Agent�.

First is a definite agreement with the Site Agent, “Full wrap, everytime.� BC4ME’s comments about fine sediments and the filter mesh make sense. Here, in Middle Earth, plastic “perf pipe� is commonly bedded in “filter gravel� as a means of fines removal. In this area there is a faux earth known as “gumbo� which in drained masses is suitable for squash, pumpkins and corn but not for anything involving resisting the forces of gravity. The typical solution, with drain fields at least, is to cover or surround the filter with “filter gravel�, as well as the perf pipe, with filter membrane. Our brethren in North Middle Earth note such a method in “Approach 2� (http://www.extension.umn.edu/distributi ... 51-04.html). Increase the filter surface enough and, with a little bit of luck, you will be viewing the eventual failure of the system from the down-side.

The “holes-up vs holes-down� controversy (http://www.pavingexpert.com/drain03.htm) was also intriguing since I was agnostic about the concept. I have an intellectual attachment to holes-up in a drainage field, as opposed to the gut attraction to holes down in a dispersal field, since the holes-up provides a smooth flow surface which can probably be hosed free of sediment. This intellectual high mindedness has a consequence of 4 to 10 inches. As noted by our brethren in the North North Middle Earth (http://irc.nrc-cnrc.gc.ca/pubs/rr/rr199/part1_e.html, 1.3 Controlling Environmental Factors, Perimeter Drainage Pipe and Gravel, Aquarius Rising, “Other systems have ...�) as well as others, the higher position of the holes-up system raises the invert level (http://www.pavingexpert.com/drainage.htm) or weir of the drain system 4 inches (pipe diameter) to 10 inches (pipe diameter plus gravel bedding). The resulting perfectly functioning foundation drain system might regulate the local water table to, or above, the concrete floor slab within the basement. The weir’d result might be the provision of a constant, but not reduced, moisture level in the basement of interest. A holes-up fundamentalist might therefore have to choose between additional preparatory ground work or a lapse into a less dogmatic perf-pipe-ism.

In either case, foundation drains, like any other gravity drain system, should be provided with sufficient “clean outs�, i.e. rodding eyes, which can be used to clear out sediment and debris. The cleanout can consist of a solid downpipe, with a threaded closure, connected to the foundation drains proper through a sweep ell (long radius 90 degree fitting) which will accommodate a hose or snake. A snake, incidentally, is an infinitely hinged, rotating “rod� controlled by guile rather than by the strict strength and authority of the rod. It can work amazingly well most of the time. When it binds in the complexity below however, it can abuse the ankles and shins of those who are close; hence the ancient, but oft misinterpreted signage, “Don’t Tred on Me!�

Since BC4ME didn't want the rain, it was unkind to send ALL of it here. Do you do earthquakes also?

[Suggers]

Welcome Mike - you're not related to someone called Mercedese by any chance?

[seanandruby]

eh?

[Mike_Missourah]

Mercedese, I don't think so. Is this someone from the trenches or from the trenchers?

[Suggers]

Sean - do a search for Mercedes - not that many posts, but bloody funny..... she seems to have disappeared.

[Tony McC]

...or been committed!