How will the flood outflow be affected by this new diversion?

[morrobay]

TL;DR Summary

Previously the flood waters entering the pump station and flood waters entering the sump had separate outflows

In diagram shown in red is a new connection diverting flood water from the pump station the receives flood waters from the other areas into an outflow channel from water from flooded road along beach. This drainage has not been effective and portable pumps have been in place at the sump. So how will this new diversion from the pump station connection into this system affect the out flow. Previously both out flows were separated. Could this impede the water from sump or even cause backflow? Photo of new connection

<9

 

[russ_watters]

Do you know what the elevations/slopes are? Was a reason given for the cross-connection?

 

[morrobay]

Do you know what the elevations/slopes are? Was a reason given for the cross-connection?

The only slope here is shown in the photo with the cross section . The drain pipe parallel and along the beach road is horizontal with no slope. As is the outflow from the sump. I believe the term is hydraulic head that denotes the different elevations in system: the flood water from beach Rd that enters the horizontal drain pipe through iron grates is about 2 meters. The junction at the sump where the water enters from the horizontal pipe is about 1 meter above sump floor. The only reason I can guess why this cross connection is being installed is to concele the very black water that forcefully gushes out from the pump station. It has been bad publicity for this tourist town with online photos etc. The very fact that you questioned this is telling since you are an engineer. By the way all the bridges, subways, and skytrains were designed by foreign engineering. And with the endless failed flood control projects here its obvious the Thais are not capable.

 

[morrobay]

https://www.pattayamail.com/news/pattaya-mayor-debunks-video-showing-sewage-flowing-into-sea-302466

 

[morrobay]

 

[russ_watters]

The only slope here is shown in the photo with the cross section . The drain pipe parallel and along the beach road is horizontal with no slope. As is the outflow from the sump. I believe the term is hydraulic head that denotes the different elevations in system: the flood water from beach Rd that enters the horizontal drain pipe through iron grates is about 2 meters. The junction at the sump where the water enters from the horizontal pipe is about 1 meter above sump floor. The only reason I can guess why this cross connection is being installed is to concele the very black water that forcefully gushes out from the pump station. It has been bad publicity for this tourist town with online photos etc. The very fact that you questioned this is telling since you are an engineer. By the way all the bridges, subways, and skytrains were designed by foreign engineering. And with the endless failed flood control projects here its obvious the Thais are not capable.

It's really tough to answer your initial question or overall concern without real details of the system. Pipe sizes, flow rates, elevation changes. Back-flow is "possible", but would only occur if the pressure in the outflow pipe by the cross-connection exceeds the hydraulic head back up to the road. That's not something you can just eyeball, especially when you aren't even eyeballing the whole system.

More to the point, it sounds like people think the black water is/was sewage. That seems to be the real question, and it isn't answerable in this thread. The two pipes leading to the pumping station either are or aren't connected to sanitary waste lines. The answer just is. Of course an obvious way to find out if you think city planners are lying about the architecture of the system would be to take a sample of the outflow and have it tested.

 

[morrobay]

Ok thanks , after two hours of rain the pump station discharge is successfully re directed out the outflow channel from the gravity flow from along the beach. That black water is in part from the street drainage.

 

[256bits]

That black water is in part from the street drainage.

So the street drainage AND from the pumping station drainage both have black discharge?

 

[morrobay]

The pump station discharge is from all the street drains where that water enters the underground drain pipes in the city. That then is carried to the pump station. And according to link in post #4 there is no sewage going to pump station. However only testing can confirm this.