{"id":16851,"date":"2026-08-12T12:30:27","date_gmt":"2026-08-12T16:30:27","guid":{"rendered":"https:\/\/www.autonocion.com\/us\/?p=16851"},"modified":"2026-08-12T08:54:05","modified_gmt":"2026-08-12T12:54:05","slug":"german-machine-iris-hartford","status":"publish","type":"post","link":"https:\/\/www.autonocion.com\/us\/german-machine-iris-hartford\/","title":{"rendered":"A German machine named Iris chewed 900,000 tons of rock out from 200 feet under Hartford and left a tank holding 41.5 million gallons, and it has sat empty for four and a half years because the hole got finished and the pumps did not"},"content":{"rendered":"

Combined sewers are one of those 19th-century ideas America is still paying for. One pipe carries the toilet water and the rainwater together, and on a dry day that works fine. When a real storm hits Hartford, the system does exactly what it was designed to do back when it was built: it sends the overflow, raw sewage included, straight into the Connecticut River. The figure cited when Congressmen John B. Larson and Joe Courtney visited the site in early August was more than a billion gallons a year, according to WTNH<\/a>.<\/p>\n

The fix has been sitting under the city since 2022. It is a 4-mile tube of lined rock, 18 feet across and 200 feet down, bored by a German machine named IRIS between 2019 and January 2022. It holds 41.5 million gallons at a time, about 157 million liters. And for the past four and a half years it has held approximately nothing, because the tunnel got finished and the rest of the project did not.<\/p>\n

That changes this fall. The Metropolitan District, the utility that runs Hartford’s water and sewers, says the South Hartford Conveyance and Storage Tunnel goes into service before the end of the year. Getting there took a decade of construction, a wall of groundwater nobody priced in, a lawsuit and a $51 million settlement.<\/p>\n

\n
\n
Tunnel length<\/div>\n
4 miles<\/div>\n
Bored through bedrock from Brainard Road in Hartford to Talcott Road in West Hartford, 200 feet down.<\/div>\n<\/div>\n
\n
THIS FALL<\/div>\n
Storage capacity<\/div>\n
41.5M gallons<\/div>\n
Per storm event, held underground instead of overflowing into the Connecticut River.<\/div>\n<\/div>\n
\n
Rock removed<\/div>\n
900,000 tons<\/div>\n
Per the project fact sheet, hauled out through shafts up to 240 feet deep.<\/div>\n<\/div>\n
\n
Tunnel cost<\/div>\n
$335M<\/div>\n
Up from a $279.4 million bid, before the $115 million pump station is counted.<\/div>\n<\/div>\n<\/div>\n

The digging was the fast part<\/h2>\n

IRIS went into the ground in pieces. In August 2018, crews lowered her components roughly 200 feet down a launch shaft on Brainard Road, across the street from Hartford’s water pollution control plant, and assembled her at the bottom. She was a Herrenknecht single-shield rock machine, built to chew bedrock and line the hole behind her with precast concrete segments as she went.<\/p>\n

She started cutting in the spring of 2019. On a good stretch she managed about five feet every 20 minutes, the MDC’s engineering director told FOX61 at the time. On January 4, 2022, she broke through into a retrieval shaft on Talcott Road in West Hartford, four miles from where she started, per the MDC’s announcement<\/a>. The project fact sheet puts the rock removed at 900,000 tons.<\/p>\n

The MDC’s own brochure notes the name comes from the Greek goddess of the rainbow. Which is a lot of mythology to hang on a sewage tank, but boring machines get named after women by tradition, and IRIS is in good company. A Herrenknecht borer called Mary is cutting a very similar sewage tunnel under the Potomac in Washington<\/a> right now, and another Mary spent this summer grinding beneath Adelaide’s suburbs<\/a>.<\/p>\n

So by early 2022, Hartford had its hole. Four miles, lined, sitting there. The hard part, it turned out, was everything else.<\/p>\n

A tunnel built for water got delayed by water<\/h2>\n

The original plan had the whole system running by the end of 2023. The Kenny Obayashi joint venture won the tunnel contract in 2016 with a $279.4 million bid, based on engineering and geotechnical reports the MDC supplied to bidders.<\/p>\n

Then the crews got underground and found far more groundwater pouring in than those reports suggested. In a court filing, the contractor said the inflows “differed substantially and materially from what was indicated to bidders,” as Connecticut Public reported<\/a>. What delayed a tunnel built to hold unwanted water was unwanted water.<\/p>\n

The claims piled past $100 million. The MDC settled at $51 million, and the tunnel’s price landed at $335 million, per figures the district gave Connecticut Public. Add the $115 million pump station, $38 million in conduit work on New Britain Avenue and $1.4 million in electrical upgrades, and the operational date slid from late 2023 to fall 2026.<\/p>\n

Delay is close to the default setting for machines this size. Chessie, the borer under the Chesapeake, lost 241 days to a 19th-century ship’s anchor<\/a>. IRIS at least got her four miles done in three years. It was the surface that took its time catching up.<\/p>\n

Gravity does most of the work<\/h2>\n

The tunnel’s job is blunt. Hartford’s combined sewer outfalls, built in the late 1800s and early 1900s, dump into local waterways whenever heavy rain overwhelms the pipes, the state’s environmental agency says. This tunnel intercepts 17 of those overflow points: ten that spill into the South Branch of the Park River and seven that drain toward Folly Brook and Wethersfield Cove, an MDC spokesperson told a UConn Journalism project<\/a> tracking the system. It also takes flow from West Hartford, Newington and Wethersfield.<\/p>\n

During a storm, the overflow drops down vortex shafts into the tube instead of hitting the river. The tunnel runs gently downhill toward the South Meadows end, so the water arrives at the new pump station on its own. “The whole thing works on gravity,” the MDC’s spokesperson put it. The pumps only earn their $115 million on the last leg, lifting the stored water about 200 feet up to the treatment plant across the street once the storm passes.<\/p>\n

Treated water then goes into the Connecticut River clean. For scale, that is 41.5 million gallons held back per storm, against overflows that have historically topped a billion gallons a year across the system.<\/p>\n

December 31 is the date with teeth<\/h2>\n

Fall 2026 is not a press-office guess. Hartford’s sewage overflows put the MDC under a state consent order back in 2006, and the federal consent decree that grew out of it was formally modified to push the tunnel’s completion deadline to December 31, 2026, according to MDC board documents. Miss that and the district is not explaining itself to ratepayers. It is explaining itself to the EPA.<\/p>\n

The pieces are lining up on schedule, if barely. At the site visit in early August, officials said Connecticut State Building Trades workers will finish the job later this year, per a release from Larson’s office cited by WTNH. The MDC has held to its fall target since 2025. The tunnel itself, remember, has been ready since 2022. It is the pump station and the wiring that decide the actual date.<\/p>\n

The tunnel is also one piece of a much larger bill. The MDC calls its Clean Water Project an over $2 billion program, required by the EPA and Connecticut’s environmental regulator, and this tunnel is its largest single component<\/a> and the biggest contract the district has ever signed. More phases wait north of downtown.<\/p>\n

The best case is a river you never think about<\/h2>\n

The strange thing about this kind of infrastructure is that when it finally switches on, nothing visible happens. No ribbon spans a highway. The river does not change color in a week. The first sign the tunnel is working will be a hard autumn rain that ends without a sewage advisory attached to it.<\/p>\n

IRIS herself is long gone, pulled out through the West Hartford shaft after her January 2022 breakthrough. What she left is a rock tank the length of 70 football fields that Hartford spent a decade and $335 million filling with everything except what it was built for. Sometime in the next few months, the dirty water finally gets its invitation. The river upstairs gets to be boring, which for the Connecticut is a genuine upgrade.<\/p>\n","protected":false},"excerpt":{"rendered":"

Combined sewers are one of those 19th-century ideas America is still paying for. One pipe carries the toilet water and … <\/p>\n

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