Converting GPM to GPD 1

[performanceplumb]

I have a Sewer District asking for a Gallons Per Day discharge for sanitary sewer only, on a small water park in Southern California. If I just multiply my GPM by how many hours in a day the park is open (10), this will be an un-realistic number. Does anyone have any type of useage factor to come to a realistic GPD number for my sanitary sewer discharge????? The information on the project is as follows.....

230 total Drainage Fixture Units
203 total Water Fixture Units
13,000 sq ft total Building Area

If you need any more information, let me know.

THANKS!

 

[rmw]

Start by assuming that every gallon that you bring into the park goes down the sanitary sewer. What is your water usage per your water meter. Then try to estimate how much of that water never makes it to the sanitary sewer; consumed by drinking, spillage to the storm sewer, watering lawns, etc.

rmw

 

[MikeHalloran]

Doesn't that same Sewer District have a recommended or statutory GPD number per family unit for sizing domestic sanitary systems?

To me (no special expertise claimed), it would seem logical to size the sanitary system based on the maximum number of family units expected to be present, since flow per family unit should be nearly invariant.













Mike Halloran
Pembroke Pines, FL, USA

 

[Zapster]

The Uniform Plumbing Code has a chart in Appendix A that gives demand fixture verses gpm. Is your system predominantly flush tanks (65 gpm) or flushometer valves (90 gpm). The problem is to determine how many hours a day that the facility operates at the code capacity. How would any of us know that? What are the consequences if you underestimate the utilization? Do you need to give a gpd for the busiest day of the year or average?

 

[PEDARRIN2]

If this is a water park, won't there be discharge from the "pool" system(s)- water slides, wave pools, etc.?

This wouldn't be part of the fixture count but would contribute a lot to the sanitary discharge load.

 

[performanceplumb]

Thank you all for the questions and information so far...

Here is some more info....

This is predominantly a flush valve system. It operates for 10 hours a day in the summer time. The discharge from the pools are not taken into account because they will be backwashed after hours. I contacted the sewer district asking if they have any type of useage factor they can give me to use and they don't have anything. I thought since they have this question on their application, they should have some type of equation to figure fixture useage, and what does and does not go down my sewer. They do not have any advice to help. It seems to me the sewer district needs to provide me with some type of estimated peak people per day, or something like that?? Your thoughts?

 

[Zapster]

Why would it be the sewer district’s job to tell you the utilization factor? Wouldn’t this be the responsibility of owner of the facility?

 

[PEDARRIN2]

Even if the pools are flushed during off hours, it will still contribute to the gallons per day load to the sewer system.

From my resource (Frankel's Facility Piping Systems Handbook) a developed campground would see 21-40 gpd/person (avg 32). A swimming pool would see 10.6 gpd/person which includes both customer and employee.

There would likely be some cross over so maybe 35 gpd/person. Maybe be conservative and use 40 gpd/person.

 

[performanceplumb]

PEDARRIN2- that is what I was looking for... from your resource handbook. That will at least give me something to go by. The reason I did not take the pool flushing into account, they already have that info. I am the plumbing engineer and they need the counts on my sanitary system. The pool backwash will be taken into account, with my GPD. My counts are the missing puzzle piece at this time.

Zapster- I forgot to tell you this is a community water park. The sewer district is the owner.

Thanks for the help guys. I will see what kind of feedback I get from this.