Sizing Lift Stations for State Park in Texas...

[adam1071]

Hi, this is my first post.

My firm is in the process of designing a new sanitary sewer collection system for a Texas State Park. They are currently on septic systems. Due to the terrain and need to minimize disturbance, we are proposing a series of lift stations for sewage collection and transfer to the nearest City's collection system. I have no flow data, but I do have the number of campsites with sewer connections as well as the number of restrooms and fixtures in each.

The state provides only vague guidelines for the total effluent from the park: 30 gallons/person/day (gpd) for overnight users and 5 gpd for day users. The park's max capacity is 482 overnighters and 1,750 day users. Using a 16 hr day, that's only 24.18 gpm... with a peaking factor of 3 I get 72.5 gpm for the whole park at max capacity. Does that sound reasonable?

I was thinking about using fixture units to estimate flows at various locations for individual lift stations (6 total), but I can't find a formula for going from fixture units to gpm. Also, I'm not sure how to determine the fixture unit count for the typical RV or camper. Can someone point me to a formula or give me some advice?

Thanks,
Adam Stockton, P.E.

 

[bimr]

Your calculations are reasonable.

A peaking factor of 4 would probably be more appropriate since this is such a small population.

One fixture unit is about 1 gpm.

Don’t believe that you can use fixture units for sizing of RV dump stations. A RV dump station is more or less a generic design.

 

[adam1071]

Thanks for the reply! I think you're right about the peaking factor. Actually, the park has individual RV campsites with 4" sewer drops for each RV to tie into. It only has a single dump station.

I'd think I could assume an RV has:
1-kitchen sink
1-bathroom sink
1-shower
1-toilet

 

[bimr]

Here are some drawings to assist you:

http://www.fs.fed.us/database/acad/enveng/dwg/civildwg.htm

http://www.usbr.gov/pmts/architecture/recfac/

http://140.194.76.129/publications/eng-manuals/em1110-1-400/a-l.pdf

http://en.wikipedia.org/wiki/Recreational_vehicle

 

[cvg]

RV fixture units are not equal to either residential or commercial ones. Pressure and flow in an RV is far less and sewage is collected for the dump station. I'm not sure counting fixture units in RV's is the best way to go.

 

[eea]

You might check your State Dept of Public Health. Illinois' are online:

50 gpd per space for an RV Park w/ Water & Sewer.

20 gpd per space for an RV Park w/ Dump Station

35 gpd per person for a Campground w/ Central Bath & Toilet

I'm not sure how the dump station RV users end up with less output than the campers, but there you go.

 

[dicksewerrat]

If the RV is using internal water system, they use less water. Once they run out of water they have to laod up and drive to a water supply.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com