Oh, well, this explains everything!

I found this online; it's the abstract of a 2000 article by DPS Director Brendan O'Regan at Proceedings of the Water Environment Federation.

For the City of Newburyport, MA, a small New England city located at the mouth of the Merrimack River in northeastern Massachusetts (see Figure 1), disposal of the biosolids from the Wastewater Treatment Facility (WWTF) was reaching a crisis stage. In the late 1980s and early 1990s, faced with a sludge that consisted of a large metals concentration as well as a pretreatment program in its infancy, it was thought that the sludge would never be clean enough to compost. In fact, it was questionable as to whether the sludge could continue to be disposed of at a landfill.

The City's proposed solution to this problem was to construct a unit operation that would thermally treat the WWTF by-product, resulting in a stabilized sludge. In addition, a double-lined landfill would also be built for final disposal of the “char” residue. The Sludge Stabilization Facility (SSF) was to be built adjacent to the DPW maintenance garage and the new landfill was to be built adjacent to existing landfill on Crow Lane (see Figure 2).

Neighbors to the DPW facility and the Crow Lane area, as well as other City residents protesting this Sludge Stabilization Facility and double lined Landfill (SSF&L) plan. They saw this proposal as burning sludge and they did not want this process to take place in the City of Newburyport. After a long and - pardon the pun - heated political debate, the SSF&L plan was defeated in 1993. The WWTF continued to landfill its biosolids, realizing the benefits of a more established pretreatment program. In the Summer of 1996, after an extensive review of the monthly and quarterly biosolids analytical data, the Newburyport Sewer Department petitioned the Massachusetts Department of Environmental Protection (DEP) to reclassify the sludge its produced at the WWTF to Type A, going through the Application of Suitability process. Following an extensive sampling and analysis program and the resulting submittals to DEP, the WWTF's Biosolids were reclassified as Type A in November 1996 by DEP.

Following this determination, the Newburyport Sewer Department entered into negotiations with private sludge composting facilities in the area and negotiated a three-year deal with a nearby composting facility. As a result of this effort, the
Newburyport Sewer Department has realized a 43% reduction in its biosolids disposal costs and the City receives up to 1,000 cubic yards per year of composted material to use on its parks, cemeteries and other City related matters.

So ... I'm going to go ahead and assume New Ventures has this little ditty ... you can draw your own conclusions.

DEP re-classified the bio-solids in the WWTF sludge in 1996 ...

Then DEP turned around in 2007 and went into the landfill using M.G.L. Chapter 21E as the reason ... this is from the 2007 civil action (Commonwealth of Massachusetts vs. New Ventures Associates, LLC):

For all the reasons set forth in the memorandum of law submitted in support of
this motion, these response actions are immediately required to prevent and
control noxious hydrogen sulfide gas releases from the Landfill that are
creating a public nuisance and threatening the public health, safety, and
welfare.

Oops, DEP (not that this hasn't already been extensively discussed).

I guess I am going bananas about the landfill ... and since I didn't feel like paying $12.50 (plus tax) for the whole O'Regan article, this is all any of us gets.