Sewer treatment plant costs

Does anyone have a ballpark idea what it costs to replace a Sewer treatment plant for a 75 space park?



Really hard to say without more Info. What permit conditions are you required to meet? Total suspened solids (TSS), biochemical oxygen demand (BOD), Nurient removal. When will your permit expire? Will they require nutrient removal next renewal?

Are you required to remove nutrients? Nitrate permit limits are getting pretty standard any more (nitrates, ammonia, total inorganic nitrogen, nitrite, etc). Phosphate permit limits are not as common yet.

My thoughts are package plant for 75 homes no nutrient removal 300 to 500k. Nitrate reduction 600 to 800k. Low end will get you a basic package plant but it may not get the job done if you have tight BOD or TSS limits.

Thank you for the expedient reply Phillip. I know it’s a question without specifics. The owner is going to sell, wants an inflated price, and oh by the way, he has been told by the authorities that he has to replace the plant!

Apparently, he isn’t going to do the replacement himself, and he has done zero work to even get an estimate. I guess he’s hoping for a really dumb buyer who doesn’t know it’s going to be a huge expense to replace it to code. The park isn’t in the city, so I guess it’s the TX DEQ after him. Because his asking price has been so high, I haven’t pursued a quote myself yet with any vigor. The seller has a big dose of reality on the way about what the park is worth with this big CAPEX hanging over its head.

I threw out a guesstimate number of $300,000-500,000. I’m not sure if he just didn’t like that I wasn’t the dumb guy, or he really doesn’t know what the cost is going to be, but the response was muted.

Thanks again,


It is usually a hard sell to tell someone their park is now worth 500k less just because they got a letter from the deq. The plant has probably been “failing” for years the owner just didn’t know it.

I put in a new septic system in SD for 75 homes 2 years ago for $150k.

That sounds inexpensive. I am very ignorant regarding these systems. I suppose there’s several types. I notice you used the words “septic system” as opposed to sewer treatment plant. What kind of system did you install?



It is a standard septic system like just about every rural home has, only mine is on a bigger scale. I have 9 systems in the park, most of which have 3,000 gallon tanks, a pumping station and their own drain fields.


Thanks for the explanation and pictures Randy. I think that standard type system is excellent and time tested. Unfortunately, it is also dependent on soil percolation capability. Too much clay in the soil where the park is located prohibits that basic system from being allowed.


Do you have a pic of the pumping station? I’d be interested if you could post.

The pumping tank is the smaller rectangular tank in the middle. The 3,000 gallon holding tanks are made by stacking three of cylinder sections.

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Maybe this photo is a little better.


Those are great photos! Thanks so much.

I just finished putting in an Advantex System in a park to cover about 16 units. I would guess that this is about as pricey as it gets ( California, difficult terrain, little room, did I mention California?) . The Advantex is essentially a full treatment system. The cost was around $110k.

Thank you for the info MikeC.

Phillip, is there a way I can reach out to you. You seem like the expert on these systems. thanks!

Feel free to call me at 503 734 7400