Septic to Sewer Conversion

Need advice. I have a mid-size park in Northern California. The city has installed a new sewer main in the street out front and will require a connection at some point. The laterals are stubbed up to the park property line now at each entrance. We have numerous septic tanks. Has anyone done such a conversion? Did you connect the new sewer piping to each mobile’s pedestal or did you connect the piping just before the septic tank inlets? Connecting to the existing piping at the septic tank inlet would save a lot of work and money. Once connected the septics would of course be abandoned. Hopefully someone will have done this before. Any help with budgeting would also be appreciated. The routing would be down the park’s asphalt streets. The septics and mobiles are on both sides of the street. Thanks a lot.

Is your current system a gravity or pressurized system? What is the grade to the citys line (you will have to include the deepth of your pipes verses ththe city’s as well)? If you luck out you can gravity into the city system but if not you may have to gravity all your lots to a lift station and pump pressurized into the city main.

Poop flow downhill or so the saying goes :slight_smile:

Most likely plumb the lines before existing tanks. Your existing mains may not due well with out the tanks catching most of the solids. Lines might be to small… may need new bigger pipes


The city’s permitting may require you go one way versus the other too. I would check there before you get too far along so you can firm up your approach. Sounds like you’re thinking about all the right things.

Also budget for the connection fee to the road, as well as any requirements to decommission the septic tanks. Some cities / states don’t require much, others must pump and infill with sand - hopefully Cali. won’t require complete removal of them or something absurd.

What is the piping material to the septic tanks, and how old? If it’s older cast iron or tile, replace it for sure.

Phillip, thanks.

The current system is gravity. Four to five mobiles connect together at the rear of the lots and end up at each septic tank (also in the rear). I didn’t want to get into the depths of the sewer laterals at the PL with my question because I believe the City stubbed them too shallow. I had them increase the lateral diameters but didn’t think I’d have to tell a Civil Engineer how deep. The City main in the street is 8’ i.e. and they stubbed our laterals at 4’ i.e. This is the same depth they stubbed to single family residences.

I’m expecting to go back into the street to run new laterals but who will pay for it will have to be determined. As I think about it now, the existing piping may be Orangeburg. In that case I wouldn’t have a choice but to run new piping. I just didn’t want to saw-cut and trench up every driveway to each pedestal. May have no choice though and I certainly want to avoid a pressurized system.

Have you ever done one of these conversions? I can imagine that it can get expensive.

Thanks again

Sorry for some reason my reply went to jhuston.


Thanks a lot.

You’re right but I wanted to run my idea of connecting at the tanks by you guys before I contacted the City. The connection fees and permits are very expensive. I plan to try and get them to finance it with a low interest loan. That they will probably do. I’m also going to try and get them to finance the construction costs the same way since we are trying to keep from raising the rents too high on our low income tenants. For that I may not be so lucky.

The tanks will have to be abandoned by pumping and then breaking the tops and bottoms and filling with pea gravel.

Thanks again


I’m afraid it may be Orangeburg.

One other thing came to mind when you mentioned this…

Some cities, especially smaller towns, can waive fees or lessen them in exchange for something that will either increase their tax basis or improve the community as part of the broader city. So basically if you can make an argument that any money they waive from the connection or impact fees will be applied to something at the Park then there could be dual benefit.

For a turnaround Park I had under contract was looking at the cost to move from master meter to individual meters - the town was going to waive 75% of the individual water meter connection fees (3K for each meter) in exchange for addressing all of the code violations (~75 violations over 5 years) and could perform over 6 months with no new violations.

You just need to figure out the levers that influence the city and it could be a way for you to lessen the cost of infrastructure and put that money instead towards tangible improvements that can better position your Park for future rent increases.

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It may come down to repiping the park like you say. Pitch the environmental benefits to the city see if you can get them to wave some fees like @jhutson said. Find out what lever works better environment, taxes, … Be prepared to repipe if necessary better to go bigger on pipe size. I doubt you will get away with not repiping. Prices are all over the map depends on where in the country you are. Get some quotes.

Phillip Merrill

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Thanks to everyone. Lots of food for thought.