Odor control is an issue that PS1 and PS2 have been struggling with since the Town started using the force main. The odor results from naturally high sulfur in the area, in waste, and the long detention times in the wet well and the force main…
– from the Pagosa Springs Sanitation General Improvement District agenda packet, January 7, 2020
One of the first things we noticed — driving into downtown Pagosa Springs from Santa Fe, NM for a weekend vacation in 1987 — was the charming odor of rotten eggs. We didn’t know, then, that the name of the town “Pagosa Springs” was originally derived from two Ute Indian words: “Pah” meaning “water” and “gosa” meaning “has a bad smell.”
We didn’t connect that peculiar odor to a chemical known as hydrogen sulfide. Nor did I notice that, after just a few minutes sitting beside the Spa Motel swimming pool, I could no longer smell the odor.
That’s one of the odd characteristics of hydrogen sulfide gas, also referred to as H2S. First you smell it… and then you don’t.
From the Illinois Department of Public Health:
…Hydrogen sulfide gas occurs naturally in crude petroleum, natural gas, volcanic gases and hot springs…
Hydrogen sulfide gas is also known as “sewer gas” because it is often produced by the breakdown of waste material. At low levels, hydrogen sulfide gas has a strong odor similar to rotten eggs. You can smell hydrogen sulfide gas at lower levels than may cause health effects, so smelling the gas does not always mean that it will make you sick. However, at higher levels, your nose can become overwhelmed by the gas and you cannot smell it. At higher levels, hydrogen sulfide gas can make you sick and could be fatal.
I took chemistry in high school and learned a little bit about sulfur, and hydrogen, and oxygen… and that smattering of adolescent tutelage probably helped me get through a lengthy presentation last night, at a meeting of the Pagosa Springs Sanitation General Improvement District (PSSGID) board… where Town Public Works Director Martin Schmidt and Utilities Supervisor Gene Tautges treated the board to a 20-minute lecture on sewer gas control, and options with various dollar amounts attached.
The seven local residents sitting on the PSSGID board of directors also serve as the Town Council, and meet as the PSSGID board every couple of months to deal with sanitation issues and budget challenges. It seemed to me, last night, that the eyes of some of the board members began to glaze over, about 15 minutes into the lecture. (My own eyes probably glazed over as well.)
In this case, we were hearing — not about the naturally-occurring hydrogen sulfide gas generated by the famous “naturally therapeutic” Pagosa Hot Springs — but the hydrogen sulfide naturally generated in a poorly-designed 7-mile-long pipeline and drifting out into Archuleta County neighborhoods along the way. That pipeline and the two associated pump stations, PS1 and PS2, deliver sewage from downtown Pagosa Springs uphill to the Pagosa Area Water and Sanitation District (PAWSD) sewer treatment plant near the Vista mobile home park.
It’s a pipeline that should never have been built, but which was nevertheless shoved down our throats, starting in 2012, by two poorly-informed government boards conspiring on a project that seemed, to them and to their consultants, to make some kind of sense. We now understand more about the mistake, as the cost of operating the pipeline continues to increase, year after year, along with the monthly rates charged to downtown PSSGID customers. But we’ll dig into the issue of rising costs in a later installment. Today, we’re going to focus on smells… and corrosion.
From yesterday’s presentation by Martin Schmidt:
Odor control is an issue that PS1 and PS2 have been struggling with since the Town started using the force main. The odor results from naturally high sulfur in the area, in waste, and the long detention times in the wet well and the force main. Staff worked to make our previous pilot project successful, but it did not get close to the levels of H2S that were stipulated in the contract. Staff, with engineering support, has brought back options for the Board to consider. The spreadsheet below shows options, their upfront costs, and the 20 year anticipated operating costs…
There are two (unexpected?) problems the Town is attempting to address with our sewer pipeline. One problem is the irritation caused to innocent residents living near the pipeline. The smell of rotten eggs blends poorly with rural suburban living and beautiful mountain vista, I am told.
The other problem is corrosion. Although the pipeline itself was constructed of plastic pipe, the two pump stations contain machinery made with metal parts, and are controlled by electronic equipment that also contains metal parts. Delicate metal parts, in some cases.
Another name for the chemical hydrogen sulfide is ‘hydrosulfuric acid.’
(We will note here that the agreement to build the sewer pipeline from downtown to the PAWSD Vista Treatment Plant was originally promoted by PAWSD staff, and its design and construction was a joint project by PAWSD and the Town. As I recall, the engineers who designed the project — Topeka-based Bartlett & West — were good buddies with a former PAWSD manager. But the Town government now seems to be dealing with the H2S stink without any financial help from PAWSD. That doesn’t seem fair. But, hey, who ever said the world was fair…)
We are here listening to Utilities Supervisor Gene Tautges at last night’s meeting:
“I think it’s really important to stress that it’s not just odor. It’s corrosion. The odor, we can all smell. The corrosion that’s happening down in those wet wells, and the vapors that come up into the [pump house] have already reduced the life of some of the equipment. So we’re trying to solve two problems…
“Corrosion is… I ran into it again today, working on an electrical panel. It looks like the panel is 15 years old, and it’s just a few years old…”
How could so many smart people, with so much experience designing, constructing and maintaining sewer treatment systems, have gotten this particular system so wrong?