STEP system discharge to existing MH - Gas problems?

[sjohns4]

I'm doing an alternatives analysis to extend sewer service to approximately 30 customers. One of the options I was asked to investigate is a STEP system either tieing into an existing gravity sewer MH or providing a small package plant.
My question: since the STEP collection system is transporting liquid that has had a day or few detention time in a septic tank, will this be likely to cause gas problems once we discharge to the MH?

Any thoughts or expirences here?

Thanks,

Mike

 

[francesca]

Clarksive, TN has an out-of-town subdivision (~300 single family homes) that had a STEP system discharging into a city manhole. It worked fine (or those living near the manhole didn't complain), though the plan was ultimately to build a community effluent filter on-site because they didn't like paying the city.

 

[gibfrog]

Check out the 1991 USEPA Manual for Alternative Wastewater Systems (EPA/625/1-19/024)

http://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=300046DW.txt

and the 2008 Water Environmental Federation Alternative Sewer Systems Manual of Practice FD-12, Second Edition

http://www.amazon.com/Alternative-Sewer-Systems-Manual-Practice/dp/0071591222

Basically, septic tanks are vented through the house that they serve via the existing plumbing. Just try to minimize splashing at the point of connection. You can use use "t-lok" on the manhole, but this maybe excessive.



Clifford H Laubstein
FL PE 58662

 

[bimr]

Probably not that big of a problem since the mh will have a sealed lid and does not vent. This would be a bigger problem at a lift station that has a higher number of air changes per hour.

If the mh is located close to something, you might be take more precautions.

If you are in the south, the warmer temperatures may make this more of an issue.

 

[dicksewerrat]

Lest we all forget, that is not an odor, it is an aroma. That aroma has paid me for 45 years and still doing so. Thank you.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[gibfrog]

I forgot to mention that the septic tanks will need proper maintenance to fuction properly. If you do not maintain them, your effluent pumps will fail unless you use grinder or solids handling pumps, you will lose your primary settling volume to solids and you will lose your retention time to settled solids. You can end up pumping rawer waste that has a much "fuller" aroma then properly decanted and retained effluent.

I recently worked with a RV park that has a older section with 60 RV sites that flowed to a large three chambered septic tank and then gravitied to a lift station, via a standard gravity collection system that picked up an additional 90 RV sites. No odors at the downstream manholes and no aroma at the central lift station.

Clifford H Laubstein
FL PE 58662