Separation distance between potable water tank and sewage holding tank

[m2e]

Doing some preliminary research for a project that involves a building in a remote site. It requires an underground potable water tank and an underground sewage holding tank. We intent to put them into the same hole in the ground exterior to the building and dig the hole deep enough for the tanks below the frost line.

Can't seems to find much information for this scenario because mostly literature covers septic field and ground well. The tanks we're planning to use are plastic tanks.

Questions are:
1. What is the separation distances between the two tanks?
2. Does the potable water require treatment before feeding into the building's domestic water system? (Provided the water is treated potable water filled by trucks on a weekly basis).

Thanks.

 

[coloeng]

The typical recommended distance of a cistern (potable water storage tank) and a sewage vault is 25-ft. I would recommend against placing them in the same hole.

Depending on how quickly you use the water in the cistern, you may want to make provisions for maintaining the chlorine residual. You can either add a bit of beach every couple of days, after checking the chlorine residual of course, or add powdered chlorine as necessary. A residual of 1ppm should be adequate.

 

[cht13er]

Minimum clearance between a sewage holding tank and a well is 15m according to Ontario Canada's building code (Table 8.2.1.6.C if that helps at all).

Different excavations would definitely not be detrimental, as coloeng noted.

Do you know depth to (seasonally high) groundwater?

 

[PEDARRIN2]

International Private Sewage Disposal Code Table 802.8 dictates;

25 feet from cistern

These are minimum horizontal distances for treatment tanks.

It doesnt spell out distance for holding tanks, but I would think it would still apply.

 

[cvg]

water and sewer lines in the US are generally required to be separated by 10 feet minimum. Water wells require a sanitary seal and separation distance is larger due to the risk to the aquifer.

Exceptions might be made for installation in a casing, mechanical or welded pipe and pressure testing to 150 psi or concrete encasement. state and local regulations may be more restrictive. If they cross, sewer should always be below water. I have not seen a joint trench for water and sewer ever allowed.

 

[m2e]

Thanks for all the replies, they help pointing me to the right direction.

 

[bimr]

"Sewers, drains, standing water, and similar sources of possible contamination must be kept at least 50 feet from the reservoir.

http://10statesstandards.com/waterstandards.html#7.0.3

I think that 50 feet is typical.

The local agency having jurisdiction is the organization that will provide you with the requirements.

Incidentally, one would doubt that you can bury a plastic tank unless you put it in a vault. Most tanks are designed to hold water and are not structurally designed for exterior loads.

 

[ch81pc]

If they have to go in the same hole, dig the sewage tank lower so that TWL is below BWL of the pottable water tank.