Where to connect drain pipe 1

[AAEC]

We are planning to construct a concrete secondary containment with a sump to drain out either rainwater or other liquid mix. In order to drain the liquid inside the containment, an inlet pipe will be connected at the sump directly either to an existing drainline pipe or to an existing concrete catch basin. My question is where should I connect the pipe? Should it be to the existing drainline pipe or to the existing concrete catch basin?

 

[Hoagie]

You've written 'other liquid mix'? This can only be interpreted as one thing: you will be discharging an effluent. You can't just make an undocumented connection.

You should check with your local water board (or State Offices) for design requirements and permitting needs. In all liklihood, you will need to discharge the effluent into a sanitary sewer and not into a drainage system/course.

The waterboard (or State) will most likely require calculations a/o report, and other measures...such as a oil/water separator (or other BMP) prior to discharge.

I urge you to hire an experienced, civil PE that is insured.

 

[cvg]

connect to a catch basin and consider a sluice or flap gate. Hoagie's concerns are valid if you are discharging off the site to either a sanitary or storm sewer. However, if it is effluent that you are planning to discharge, it might be better to pump it and truck it out for pre-treatment and then discharge to the POTW.

 

[3feethighandrising]

Connecting any secondary containment to the storm system is a definite violation in most instances. This should be connected to the sanitary sewer with the appropiate sewer connection permit. After regulatory review they may allow connection to the storm sewer if there is a manual gate/valve that is normally closed, and you can prove there are no contaminants present by testing, before discharge.

Look at the regulatory stormwater manual's definition of what qualifies as an illict storm connection or discharge.

 

[AAEC]

I failed to mentioned that all our storm sewer is treated in our treatment plant so as the other liquid mix. Just got an update that the other liquid mix will be neutralize before it goes in the storm sewer pipeline. This is better for me since I only need to be concern with one connection instead of two. To re-iterate my question above, I wanted to know if there are any advantages or disadvantages in connecting the new drainline to either the existing storm sewer pipeline or catch basin. Both the storm sewer pipeline and the catch basin are in the same drain system. If I connect my new drainline, I will have to cut the existing drainpipe and place a tee or a wye to make the connection. If I connect my new drainline to the catch basin, I will have to core drill the concrete catch basin and seal the annular spaces.

 

[Hoagie]

Assuming that it is okay for you to discharge the mixture into the drainage system, and that you have desirable soils (easy digging), and plenty of money, I recommend that you run a parallel line and bore into the manhole. I think this would be the most expensive of the options. The pros would be that your discharge will meet its destination each-and-every time. Another benefit is that you’re not impacting the existing storm drain’s capability. For instance, if the existing storm drain already runs full during a moderate rain storm, then you connect to it, you be interfering with the existing system..this may be a problem for the upstream land holder. To assure that you don’t interfere, you will need to quantify both the existing drainage flow conditions and the proposed conditions to assure there is adequate capacity in the existing line…this will require that a drainage study be completed, and this of course means more money.

If you have less-than-desirable soils (rocky, organics, weak fill), and choose to intersect the existing storm line because there will be less trenching, then connect to the existing line, but do so with a manhole. Manholes can be ordered in prefabricated sections, or can be built in the field (block type). Manholes aren’t very expensive, but will require additional construction time be undertaken as compared to the first option.

Placing a buried tee or wye is a risky idea. It’s highly probable that you will get a clog at the intersection at some point in time….unless, you are 100% certain that your discharge is free of debris and sediments, install a manhole. Some engineers may argue that you can install a cleanout or rodding inlet, but it seems to me that spending a little more money for a manhole is smart-money spent.

You will need to perform a costing exercise to determine the best choice for the situation. In regards to cost data, I would first speak to a local, reputable contractor to determine his pre-profit cost. If you don’t want to speak to a contractor, then RS Means is a popular publisher of cost data for construction. Beware: I've found their data to be inflated, laughable.

I hope this helps.

h.

 

[AAEC]

Thanks for all the reply especially to Hoagie for the comparison between intersecting the existing line vs connecting the new line to the existing catch basin/manhole.