Commercial Rooftop Drainage Solution


So we've been called out to take a look at a commercial drainage project and I want to walk you through what the solution is. So, I'm going to start kind of at the end of this line. On this building, we've got a large commercial building, we have four points on this building which really technically isn't enough, so a lot of water is coming out at two points on the left side of the building, two points on the right side of the building through what's called a scupper, which is basically a roof drain that will discharge towards the top and this water will rush out of the top of the building onto the ground like a waterfall. Once that water flows down this way by gravity on top of the surface there is a large drain basin existing in the ground during basin is re about here about 10ft behind me and that during Basin discharges with a 6inch corrugated pipe that only comes partially way down the hill and there still it has to run over all of this dirt and gravel area before it hits a parking lot, which means it's going to carry a lot of sediment and this water it's going to carry a lot of debris, it's never going to allow anything green to grow here and that's why you see all the rocks on the surface that's just a sign of more erosion and sentiment and discharge from this pipe. So, step1 in this process is actually step5 or I should say down the line when we end this system, we're going to take out this corrugated pipe, upgrade it to a 6inch P.V.C. pipe, we're going to take it underground through this area, and we're going to discharge through two points at the curb with 4inch P.V.C. and I just said 6inch, I have to use 4inch at the discharge because the curb is only 4inches thick so, a 6inch pipe won't fit through the curb so when I get towards the end I'm going to split that 6inch pipe into a we use a wire fitting split it into two 4inch discharge lines. That is going to allow the water to stop running so heavily on the surface which is going to in turn allow me to establish some ground cover, some grass seed, some fescue seed and some wheat straw. Here, is the drain that I talked about, that is collecting surface water over time that due to the age of the building in the movement of the land this drain is not collecting with very good efficiency, there's a lot of water that's bypassing the drain or missing the drain in some cases as we get towards the back of the building even falling off in the wrong direction. So, there's an existing 6inch P.V.C. inlet pipe coming in through here that collecting from several interior drains and surface drains. We're going to be attaching into that 6inch pipe, that 6inch pipe has already routed below great site does save us a little bit of work and a little bit of trouble but through after we're done tying in these new scuppers and downspouts, we're going to re-grade the entire side of the building to create a swale the area just a nice shallow swale down this area and then, we're going to vegetate this with fescue seed and we don't expect that the fescue seed is going to perform fantastic right in the center of this swale, because water's going to be moving down it, but it will be providing function because right now, water is allowed to collect and run off on and width of this area's probably 14-16ft wide. We're going to be channeling that to an area that's about 4ft wide to give it more direction and to flow directly to that drain basin. Our first scupper is up here on the building and you can imagine this is 15ft-16ft off the ground and this is going to just allow water to pour over here like a waterfall and it's running out right in front of this gas meter. So, the contractor, the general contractor is going to be installing downspouts and interior drains that come out, our job is going to be to bring in 6inch pipes to this location underground and tie into another existing 6inch pipe which is already below the surface. So, that's location number one on the left side of the building. Here is our 6inch pipe this area here is provided as a clean out for that pipe and here's our second scupper up here on the roof towards the back left side of the building and that is where more water is running this area out and you can just see just from the pounding of the water coming out that this drain boxes really relatively useless at this point in this location. So, we're going to eliminate that direct pipe everything; so as we get to the back left side of the building, one thing that you can see is water which should ideally be flowing all towards the front from the area that we just walked past, is actually just because of the overtime how the greatest change due to water flow is actually flowing backwards, back around towards the back of the building which is not an ideal situation, because once it gets to the back left side of this building, there was a riverbed that was originally put in to capture water and make it flow which it probably did, but you can see how much higher these rocks are now to the ground. They’re probably 4-5, some areas 6inches higher than the adjacent ground area and that's just because of water runoff pushing this dirt over time into rodding it away. So, what we're going to do is re-establish this great we're going to lift it up we're going to vegetate it with fescue seed and we draw and we're going to re-grade this area so now everything is going to flow back toward the front of the building. So, that is going to correct the situation, it's a long term solution P.V.C. pipes are not going to have to be cleaned very often, they're not very easy to clog so they're going to stay free running if they do need to be cleaned, they'll be cleaned out points shorter than 100ft, so plumber snake a go in there very easily but we don't expect that there's going to be very high maintenance on this, and we do expect that this will be a permanent solution. So, we're going to take a walk over to the right side of the building and I’ll pick it up there. OK So just on the right side of the building that was only partially true, I am headed there but I want to talk about this back concrete area this is sort of a new gathering recreation outdoor living area for the employees at this company. And it looks really nice, got a nice stone wall on the inside but one of the things is, this stone wall is actually trapping water. So, it will most becoming a swimming pool when it rains. There is a surface drain basin right about there and it's kind of like a pool something you would see near a swimming pool, it's got a long channel drain probably about 16ft long by 4inches wide which would work great but the channel drain is completely clogged. And I'm looking at the elevations and I see that the pipe discharges out the side and there is very little pitch. So, I don't expect that even if we were to clean this channel drain completely, that it would still function all that great. Here's what I'd like to do, I'd like to go into the back of this wall and I'm judging this by some point I will have to shoot the level with a laser but it appears to me that along the back of this wall, if I had wheat poles that would allow this water to come out. When I say wheat poles on something like this would probably be 2inch holes that I would drill along this wall and this side of the wall, I would probably have 3-4 two inch holes and then perhaps 1-2 on the back portion of the wall. If I had these 2inch holes, it would allow the water to come through during very quickly after a rainstorm and I could collect the water on the outside, through a drain basin, that would have the correct pitch and would be very easy to clean. So, that would be one of the plans that we have is to drill these 2inch holes and then to Sleeve them so we can allow the water to drain out of this area. So, now I'm going to go to the right side of the building and I’ll pick up from there. OK I am back on the right side of the building, and I want to kind of give you a shot of this building again. We're dealing with 2stoppers; one at the top here and one of the top towards the front another drain basin here that is running out same situation is the force of the solution for this will be, again the general contractor will run a downspout, we will connect in with a 6inch P.V.C. pipe that 6inch P.V.C. pipe is going to run towards here but I've got an obstacle, I've got this sidewalk in the way and on the opposite end of the sunlight, let me back up my choices here; I can discharge the water right here on the inside of the sidewalk through what they call a 4inch pop up a meter which has a spring when and a lid and when the water line fills up, it creates pressure on the spring pushes it up and allows the water to discharge in a 360o radius, supposed to be at a slower velocity although they can still put out quite a bit of water. The problem is, once I discharge it on the sidewalk, it's going to hit this wall of ivy and it's going to kind of dam up again and could create future problems. So, what I think the most permanent solution for this area is right to be too soft cut the sidewalk and route the pipes underground let's take it out about 3-4ft into this natural wooded area to allow the water to discharge or it's not going to create a problem for people and it's not going to get in the way and then we'll just pour a little bit of concrete to fix it all up and we're done. So now, I'm walking to the front right side of the building and as I get over here, I can see in this curb is actually an existing 4inch discharge pipe right here in this curb, so what we're going to be doing again is we're going to be taking a 6inch P.V.C. pipe underground and we're going to this target the two forms P.V.C. pipes that are in this curb and that is a solution to the project.


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