Wastewater sampling to support septic system

[jjdj]

I work in the construction development department at a restaurant company. I have a new site, in Connecticut, that is will occupy a space that was former pizza place. The entire strip center is tied to a septic system. The CT Dept. of Env. Protection is requiring us to collect wastewater samples from 1 or 2 of our existing sites. They want us to collect the sample from a septic tank. The real problem is our company has no existing septic tank sites to collect samples from unless you take a sample from a cleanout pipe (which would seem nonrepresentative).

My question is, is there a way to estimate our discharge concentrations (based off of our seat count/meal count) of the following requested analytes:

BOD - Biological Oxygen Demand
* Total Nitrogen
* Total Phosphorus
* Suspended Solids
Thanks and sorry for the long message.

Don

 

[bpattengale]

Based on your post what it sounds like is that the CT dept of env. protection wants to determine the "strenght" of the sewage discharged from the build to determine if it the existing septic system can handle the load.

I'd locate the locate cleanout on the main drain of an existing resturant and take samples there. As you stated a single sample wouldn't be represenative so you would most likely have to take several samples over the course of a day over a period of say two weeks. That would give you enough data to provide a reasonable estimate of the "strenght" of the sewage.

 

[bimr]

There is no universal method to predict wastewater strength and flow from a restaurant.

Probably the simplest method is to use the domestic water usage data (from the water bill) to estimate the wastewater flow volume.

You would have to use a composite sampler to estimate the wastewater strength if you wanted accurate information. Even then, the estimate would probably not be accurate unless you conducted the testing for a very long period of time.

You would probably be better off to use the typical composition of untreated domestic wastewater values found in Chapter 3 of Metcalf & Eddy. I don't think the regulators would argue with you if you used values from the book.