Fixture Quantity, Septic Tank and Leach Field Sizing 2

[AN1]

I have a question on sanitary fixtures, septic tank and leach field sizing

I have an office type building that will be used for 3 shifts; each shift will have 10 occupants.

Also and potentially more critical, there is a conference room in this building that can hold up to 50 occupants, but it will only be used periodically: that is, once or twice a month.

Would anybody be able to provide guidance on what number of occupants I should use for the quantity of sanitary fixtures, and the sizing of the septic tank and leach field?

Also, are there any recommended design standards that will prescribe sizes based on occupant load?

 

[zabrab]

Yes there are standards, but, unfortunately, they are not standard; they vary from Jurisdiction to Jurisdiction. Here is a link to the standards here in Pennsylvania:

http://www.pacode.com/secure/data/025/chapter73/025_0073.pdf

Sewage flows are discussed in section 73.17, absorption area sizing is presented in section 73.16, and design of the other elements is presented in other sections of the regulations. If you need to have something now, but have no local regulations, The regs might be useful to approximate the size of the system.

The better solution would be to check with your state DEP or local agency responsible for administrating onlot sewage treatment for the prevailing requirements in your locale. They will probably be similar, but will have differences to reflect the soil and climate conditions present in your area.

 

[LHA]

I don't know much about fixtures, if there is an Architectural or Plumbing forum, try posting there.

Generally, you will size the tanks for those spikes (when conf area is full) along with the diurnal peaks. Then you size the pump based on a constant flow out. Last, you will size the leach field based on the loading for the total uses (all the people and what they are doing).

I am also from PA, so I would use the ref zagrab cites. However, his last paragraph is required. Do what you regs require.

Engineering is the practice of the art of science - Steve