charlie's drainage comments

I am zeroing in on the drainage issue. See my attached diagram. This is how I currently understand drainage patterns after our recent discussions. Heavy red arrows represent concentrated flows. Lighter arrows distributed or sheet-like flow.

1- If in fact point B is at a higher elevation than point A, then we will need another scupper at point B. Please let me know what the slab elevations are at points A and B.

2- Scupper 5 and 6 will be points of flow concentration.

3- Significant concentration of flow is inevitable on both the north and south sides of wall ‘W’

4- Flow will concentrate along most medial walls.

5- Since there is only one drain north of the ramp, we will need another scupper at location 7.

6- After our conversation, I was no longer confident about the flow pattern near scupper 4. Will flow be toward the NW or SE along the beam (need to elevations along this obstruction)?

7- I think it makes more sense to manage water through one (or two) scuppers along wall ‘X;’ i.e., at A and/or B. The reason is that for water to follow the slope of the slab, it will have to flow through a number of additional scuppers and them be dispersed in a sheet drain under the decomposed granite pathway. I am concerned that this drainage path will be inefficient.

Please provide more information about what is happening where your plan shows a boundary between orange and blue. What is preventing flow from draining across this line? My understanding is that there are no drains along this axis.

I got the impression during our conversation today that you have been assuming that the medial walls will havemany scuppers; i.e., sufficient to prevent these walls from acting like barriers to flow. Do you have elevations of the walls, showing these openings? I am very concerned that root protection will compromised at scuppers. It will be challenging to hot-air weld the root-barrier so that it can protect the waterproofing in the opening. This is one reason that I have been assuming that the number of scuppers would be few, large, and strategically located.

Even if your plans are to have many scuppers through the medial walls, I still think it is important to have the ‘master’ scuppers in the locations that I have shown. These should all have vertical shafts that allow them to be inspected and serviced.

It would be great if you could provide a CAD file with spot elevations for the slab shown.

Since we are on a short fuse- please send current CAD plans and sections. We will use these as a basis for preparing details.

I will be available to discuss this some more on Sunday. Call my cell phone.