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French Drain vs Swale - effectiveness at controlling rain runoff

French Drain vs Swale - effectiveness at controlling rain runoff

French Drain vs Swale - effectiveness at controlling rain runoff

I am evaluating some options to keep rain runoff from my neighbor's property from getting as much onto my property by my house. His property has a fairly steep slope down to mine, and mine has some slope, but some of that run-off pools along the side of my garage. I'd like to divert that runoff right when it gets onto my property.

If I understand right, a sloped swale would maybe be more appropriate for capturing rain runoff and moving it elsewhere. Is a french drain more appropriate for draining an area of ground where water pools/sits (it "sucks the water out" and moves it away)...versus being as effective at just capturing all runoff and diverting it? Thank you!

RE: French Drain vs Swale - effectiveness at controlling rain runoff

open swale or underground pipe with inlets can handle surface water drainage. french drains are intended for subsurface water drainage

RE: French Drain vs Swale - effectiveness at controlling rain runoff

Check with your municipality or builder on how your lot is supposed to be graded and where the swales are supposed to direct water to before you change things.

RE: French Drain vs Swale - effectiveness at controlling rain runoff

A swale is easier to maintain and care for, once it is installed, and it should be graded to drain into the city storm water system at the curb, at the lot boundary. It does take up a little more surface area to make it mowable, etc., with gradual side slopes, and the like, but then it takes very little maintenance. Underground drain pipes and French drains don’t store much water, can plug up and need extra attention, and must drain to daylight at their lower elevation. Adding to GeoEnvGuys’ thoughts, you might check with the city about your neighbor’s lot draining onto your lot, particularly if the current grade is not essentially the natural grade. Is it your neighbor’s lot which should actually be regraded?

RE: French Drain vs Swale - effectiveness at controlling rain runoff

First, you can't talk about french drains without knowing and i mean REALLY knowing what soils are present on your site. That said, swales work best and are usually the cheapest and easiest to build.... but you have to have a legal place to direct them that doesn't affect somebody else with erosion or water. there is a lot of legal history to drainage coming from one property to another, and it usually comes down to 1.What was Permitted OR 2.Historical Existing Drainage Patterns. if i were working the job, i would definitely check the town office AND call your state* stormwater program. the "*" is because i'm assuming USA and even then states operate differently... but IF you're neighborhood was constructed in this millennia and IF in USA there is a possibility you live in a state that would have required a stormwater permit that might have grading plans that can be confirmed if as-built conditions are as permitted. If you live in the USA, i would expect there are local civil/site designer or geotech firm should be around who could work with you for anywhere between $500-$15000 depending on how involved it gets... i would also suspect a lot of companies will tell you they are 'too busy'

RE: French Drain vs Swale - effectiveness at controlling rain runoff

An added comment about sub-drains. If not properly filtered they can plug. In addition, if cold climates they don't work in winter for carrying "infiltered" snow melt water.

RE: French Drain vs Swale - effectiveness at controlling rain runoff

darthsoilsguy2 - have you included an extra 0 on that $15,000? I hope you have...or else im in the wrong discipline.

RE: French Drain vs Swale - effectiveness at controlling rain runoff

Eirechch, That range is real and would be about the complexity of the land use issues and preparing for a fight with neighbors. if you have to route stormwater off-site to a neighbor property... there can be a topo survey, maybe a boundary survey, research on existing drainage patterns and land use history, stormwater modeling, permit research, maybe even a permit for the work, prepping and attending a meeting, and any certification work associated with any permit after it is done.... oh yeah, and that detail for the contractor to build. The low end $500 would be if you could do the work and confidently argue there is no change to off-property conditions without going through all that BS.... example of a low-end project would be building an intercept swale uphill of the building and routing around to a level spreader on the downhill side of the house.

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