Sanitary Sewage Flow Rate 2

[jeg1234]

Where can I find the sewer flow data for a manufacturing plan (gal/day). I need to provide the daily sewage flow.
I though of using water supply fixture units (wsfu) and converting them to gpm (water in = water out)using a diversity curve that is used in plumbing codes books. The number I get seems to much. Is this correct, or Is there another way of figuring this?

 

[LHA]

Factories and plants exclusive of industrial wastes:

35 gpd per employee at 0.08 lb BOD/day.

Cite Metcalf & Eddy's Wastewater Engineering.
Also cite PA Code, Title 25, Chapter 73.17

Remember: The Chinese ideogram for “crisis” is comprised of the characters for “danger” and “opportunity.”
-Steve

 

[daddymem]

Don't forget to take into account sub-uses as well such as cafeteria or offices.

 

[jeg1234]

Iha, does this number take in to account cafeteria or offices in the plant (factory)?

 

[LHA]

Yes, all estimated uses are based on average use of that situation. For example, it is common to assume 120 gpd per person per US household for domestic use. This doesn't mean someone thinks you drink 120 gpd, nor does it mean you flush 120, nor wash 120 worth of cloths or cars or kids. It is a statistically typical number reflecting what the act of having one typical person in a typical American residence will take out of the reservoir and put into the treamtent plant.

Likewise, the 35 gpd assumes a "typical" factory. I would assume it accounts for a small admin staff, but not a large one, such as an engineering firm would have. Also, a small-to-mid-sized lunch/break room and possibly limited food prep, but no full-scale restaruant. This is why these numbers are NOT for final design, but for rough, initial conservative estimating. You need much more info about the specific plant to pinpoint its flows.

Notice the 35 gpd does not account for any industrial processes. Those will range from nothing to many 1,000s of gallons, and will have to be addressed accordingly (if they are particularly large and/or contaminated, they will require pretreatment).

Remember: The Chinese ideogram for “crisis” is comprised of the characters for “danger” and “opportunity.”
-Steve

 

[daddymem]

Wow, those numbers seem high. Here in Massachusetts, our state subsurface sewage disposal regulations (Title V) as well as sewer connection permit regulations (314 CMR 7) use 110 gpd/bedroom for residences. For factory or industrial plant with cafeteria 15 gpdpp and 20 gpdpp without cafeteria. Are there no Town/County/State Health Boards in your area that would have guidelines?

 

[bimr]

Daddymem is correct. You also need to spell out the type of "manufacturing plant". Daddymem's flows are for a plant with no industrial waste.