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City of B’ham Should not be Incinerating Sewage Sludge

By On

I’m hitting the ground early with my entry to the Most Boring Headline of 2017 Sweepstakes. Or hiding perhaps some gem of wisdom under a pile of dross and ordure. Anyway, as the sewage plant operator said, “It may be shit to you but it’s my bread and butter.” More on this later but first some general principles:

1) “Carbon release into atmosphere: BAD”; and its corollary: “Carbon Sequestration: Good.” I learned this on the SmartTrips website - dedicated as it is to getting people to drive less and walk/bike/carpool more to burn less gas and release less CO2 into the overheating atmosphere. And this leads to the second general principle:

2) As a society, we should reduce CO2 emissions and increase CO2 sequestration. Reduce our carbon footprint, in other words. I break this almost daily as I drive a car - it’s hard to defeat a systematic requirement - but I do plant a lot of trees, and look for other opportunities to sequester carbon (composting, e.g.) rather than releasing it into the atmosphere (by burning a burn pile, e.g.). The general principle is:

3) Where there is a choice, carbon footprint of the alternatives should be a major decision factor. The City of Bellingham already incorporates this onto its decision matrix on sewage sludge options:

“Evaluation Considers Multiple Objectives

-Economic, Environmental, Social, and Operational

With “Environmental” described as “Environmentally Responsible - meet air permit requirements, manage carbon footprint, and recover green energy.” Who can argue with that eminently sensible approach? Which is why it saddens me to to report that when it last came up, the city chose the highest carbon footprint solution, which is to incinerate the sewage sludge. I recommend you check out the presentation, which presents in some detail (while still accessible to a general audience) the options for dealing with sewage sludge. Here’s a key table which summarizes the meat of the decision:

Life Cycle Costs, Carbon Footprint, and Space Footprint

Anaerobic Digestion : $32M cap/$1.1M p.a. -1,500 22,000

Drying $38M cap/$1.3M p.a. 650 24,000

Gasification $36M cap/$1.3M p.a 2,100 5,500

Fluidized Bed Incin. $32M cap/$1.1M p.a. 700 3,500

(from Page 13 of the presentation)

The city chose to continue to incinerate, which was the least-cost approach, but had the worst carbon footprint. From a carbon footprint perspective, it would be better to send the sludge to a landfill. At least there, anaerobic decomposition would take place over the eons. From a purely practical perspective, in terms of extracting value, it would be better to use the sludge to fertilize forestry lands. I do not think the city considered either alternative. But either would be better than what we are doing right now. You know, cleansing the icky poo with fire.

About David Camp

Writer • Member since Jul 12, 2009

David Camp is a cpa (Canada'86; USA'96) and MBA (Schulich'88) who toiled thirty years in the corporate salt mines, counting beans and telling stories to the auditors and whatnot. Now [...]

Comments by Readers

Michael Lilliquist

Jan 04, 2017

“Worst carbon footprint”?  Doesn’t that dubious honor belong to the gasification option?  2,100 tons versus 700 tons?  As I read it, the only option that is significantly better than fluidized bed incineration is anaerobic digestion, which is actually negative carbon output, but requires seven times the square footage. And space is tight at the treatmenty plant. Personally, I was hoping a plasma burn approach would work—but that was not in the cards.

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David Camp

Jan 04, 2017

Re: “worst carbon footprint” -I admit, Michael, to being a bit unsure on this point but here’s my logic: according to the City’s Sewage Treatment Page , sludge is incinerated “in two multiple-hearth gas-fired ​incinerators”. Isn’t this the fifth option not presented in the presentation, which was to evaluate options to replace the multiple hearth incinerators?  If so, and please correct me if I’m wrong, repairing the multiple hearth incinerators must have been the least-cost option.  I  made the further assumption that its carbon footprint was worse than any of the options presented, else why present them?

What I’m saying is space is not a factor in either a) sending sludge to the landfill; or b) sending sterilized sludge to fertilize forestry lands. And both of these are better from a carbon footprint basis (both are negative, which if we ever have a sensible carbon tax regime would generate carbon credits) than incineration. If Bellingham is truly a green city, why are we not dispiosing of sewage sludge to minimize carbon footprint? And neither of these options involve much in capital costs, especially compared to the rather expensive projects in the presentation.

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Tip Johnson

Jan 05, 2017

Because space at Post Point is tight, the clarifier area/volume is marginal and polymer flocculants are added to optimize precipitation.  The polymers complicate disposal options.

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David Camp

Jan 05, 2017

Thx Tip - yes probably not a good idea to spread long-chain polymer floculents on upland forests. However, landfill still a viable and environmentally-preferable option to incineration. And could be implemented in short order.

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Bill McCallum

Jan 07, 2017

Why isn’t anyone discussing the $880,956 contract with Brown and Caldwell to examine technologies to upgrade the management of biosolids at the Post Point plant?  There was a presentation at the City Council meeting on October 24, 2016.

The phase 1 report will be completed in May 2017,  phase 2 in December 2017 and phase 3 at a date to be determined. 

 

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Michael Lilliquist

Jan 07, 2017

Bill, I think it’s a teeny bit unfair to imply that no one is talking about the $880,956 contract to examine the city’s biosolids handling upgrade. You no doubt saw the video from the October 24th meeting, in which both Terry B. and I expressed skepticism about the contract price.  It seemed rather high.  In particular, refer to minute 10:30 in the video for that afternoon committee meeting— http://www.cob.org/sirepub/mtgviewer.aspx?meetid=725&doctype=AGENDA   Why are we spending all this money? What are we getting for it?

Staff’s answer is that $880K is a reasonable cost for the feasability-phase of an estimated $50 million project, where up to 20% of the total costs will be spent on engineering and design work up front—and this is 5% of that 20%. And it is intended to guide the later engineering and design.  That sounds reasonable, except that the scope of work seemed to be repeating work that we had already done, to reach conclusions we have already reached.  In response to my questioning and my request to look carefully at the scope of work, our public works director replied that the new contracted project would not repeat work already conducted, nor retread territory already traversed, and that the work product would be an “engineering” document providing the sort of concrete details essential to working plans for the future project. I hope so.

Are we headed in the right direction? Again, I hope so.

Thanks, Bill, for paying attention.  It surprised me that the $55 million Post Point expansion project (completed a year or two ago) received so much less attention than many other City actions, which cost a million or two.  Jack Weiss and I (and one other council member?) were on the loosing side of a vote to hold those Post Point expansion costs down to around $50 million.  This was a huge decision, in term of dollars, but not much noticed.  Except for sharp-eyed people like you, Bill, and like David Camp.

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