Hi. I want to install underground drain lines from my downspouts to move rainwater away from the house. Unfortunately, I’m on a nearly-level lot — there’s maybe a 6 – 10 inch drop from the house to the street. I’m planning on using a pop-up at the discharge end near the street and let the water flow onto the lawn and into the street (I don’t have enough room to dig a large underground cistern). Here are my questions:
1. Because of the small height difference between the grade at the house and the discharge point, will I have enough hydrostatic head to get the water to flow properly?
2. Should I slope the underground line? I need to run about 150 ft. of line and even at 1/8 inch per foot, the end point will be about 19 inches lower than the starting point.
3. To get the line to dry out between storms, should I put a hole in the bottom of the pipe at the low point (right at the discharge vertical pipe going up to the pop-up)? I live in California where we get all of our rain November – April and it’s dry the rest of the year.
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Replies
Can you tie into the storm sewers underground?
I'm pretty sure code doesn't allow roof waste water to flow into the sewers, but that's an interesting thought.
Wayne said the "storm sewers", AKA the storm drains. These are the drains for runoff from the street, and you can hook up any sort of semi-clean water drain to them.George Patterson
Where in California?
Makes a difference.
Los Altos (Bay Area)
Yeah, roof runoff may generally be run into STORM sewers (if any are present and accessible). Even if it's technically legal to run the roof drains into the sanitary (or "combination") sewer where you are, it's bad policy and probably best avoided (since you'll be forced to change it eventually).But you'll generally need some sort of permit to tap into the storm sewer, so be sure to check.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
I am pretty certain that you are not permitted to tie into storm drains or even direct runoff into street gutters in NJ.
Yeah, in some places they want the runoff to be restrained by running on the soil first -- to prevent overloading.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
In many places in California, due to the heavy clay nature of the hillside soils, They (the ahj) want the rainfall and moisture to be removed before it can soak into the soil - thus weaking the slope &/or raising havoc on the ceement slabs, roads, & sidewalks..
We still don't know where in California this is occuring...
Yeah, you often see a variety of conflicting rules on this sort of thing, due to local conditions.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
due to local conditions
And varying, sometimes conflicting, agencies.
Here in town, all commercial projects have to have engineering for all roof and paved areas. A residence can run off to the gutter in the street. But, a rental property, technically, cannot. Occupational hazard of my occupation not being around (sorry Bubba)
Slope it as much as you can manage. Especially avoid any sections that are uphill, or dead level.
Surround the bottom end with gravel, and punch several holes in the pipe to let it drain. (A single hole will inevitably clog.)
Do not tightly seal the downspout to the drain, but provide some overflow mechanism to allow the water to escape when the drain clogs. (It WILL clog.)
Provide cleanouts at each end and maybe in the middle, to clear clogs.
Edited 7/8/2007 3:01 pm by DanH
Punch a hole or two at the low point in the line, add some drain cloth between the dirt and pipe, throw in four or five shovels of 3/4 gravel, wrap the remaining cloth around the pipe and gravel and cover it up. That should easily handle the standing water in the pipe over a few weeks time after the rain stops. One other thing to do here, don't use the "open" grate type of end plug for the discharge end of the pipe. They have pop up end pieces that open under water flow but close the pipe when flow stops. This allows the standing water in the pipe to drain and keeps critters out of the line when it's empty. While it may take some time to drain the standing water in the line, the self closing feature on the end also prevents mosquitos from entering the line and laying their eggs which develop into wigglers and more mosquitos. With the West Nile bit going around, it's a good idea not to leave standing water anywhere, even in an underground pipe or drain that's open to the air.
CA might be different, having a rainy season, but in NW Ohio the key thing is getting the water coming off of the roof well past the overdig area, 10' or so.
With my mouth I will give great thanks to the Lord; I will praise Him in the midst of the throng. For He stands at the right hand of the needy, to save them from those who would condemn them to death.
- Psalms 109:30-31
This doesn't answer your original question - but here's a link to another option. Some of the water will water your grass on the way to running to the street.
http://www.rainguardusa.com/
It's actually better that way because the total amount of water that goes into the storm drain will be less. A more environmentally sound practise than having the pipe discharge right at the street. And it will easily clear your overdig.
Here's what we did in Oakland CA,
Tie the roof gutters toghether above ground with abs or pvc piping and slope them all correctlly then at the corner of the building nearest your discharge you can underground them. This does add a bunch of piping to the side of your house but once painted to match its not so noticable. On our past Victorian (a long skinny rectangle) we ran the gutters from both sides forward like this and were able to get enough fall that we could put the final discharge pipes thru the sidewalk to drain them into the street.
Daniel Neumansky
Restoring our second Victorian home this time in Alamdea CA. Check out the blog http://www.chezneumansky.blogspot.com/
Oakland CA
Crazy Homeowner-Victorian Restorer