Extra Water Underground Delays Massive Waste Tunnel Operation to 2026

By Elijah Polance
UConn Journalism

In 2016, the Metropolitan District Commission (MDC) began con­struct­ing a stor­age tun­nel to hold untreat­ed sewage and rain­wa­ter dur­ing storms. It is called the South Hartford Conveyance and Storage Tunnel and was sup­posed to be com­plet­ed by the end of 2023. But delays with the con­trac­tor and a relat­ed law­suit advanced the pre­dict­ed oper­a­tion to fall 2026.

The delays were due to excess water under­ground dur­ing drilling, said Susan Negrelli, direc­tor of engi­neer­ing and plan­ning for the MDC. She said that with such large-scale projects, there are inevitable unknown fac­tors that can­not be account­ed for before­hand.

“The con­trac­tor claimed they had more water that they had to deal with in the tun­nel as they were exca­vat­ing than the design plans showed,” Negrelli said. “So that slowed them down con­sid­er­ably.”

That con­trac­tor, Kenny Obayashi, sued the MDC, which announced the par­ties set­tled in March by agree­ing to about $51 mil­lion for addi­tion­al change orders, the MDC report­ed in a state­ment. The tun­nel con­tract was ini­tial­ly priced at $279 mil­lion, but the total cost is now list­ed as $335 mil­lion.

MDC spokesman Nick Salemi said in a state­ment sent to all media, “It is not uncom­mon for own­ers, and by exten­sion its con­trac­tors, to encounter dif­fer­ing site con­di­tions in the con­struc­tion of deep rock tun­nels, in this case a tun­nel approx­i­mate­ly 200 feet below the sur­face.” The MDC said Obayashi’s com­pa­ny, KOJV, had sub­mit­ted sev­er­al change orders for the tunnel’s three reach­es. The orders totaled more than $100 mil­lion. MDC agreed with some of the claims but dis­put­ed the amount of the extra costs. All but $28 mil­lion of the $51 mil­lion agreed upon was eli­gi­ble for Clean Water Fund grants and loan fund­ing.

The tun­nel mea­sures four miles long and runs 200 feet under­ground, with enough space for the tunnel’s 18-foot diam­e­ter. It was car­ried out with a bor­ing machine named IRIS, which began drilling in 2019 and fin­ished in 2022. It will hold waste from West Hartford and south­ern areas of Hartford.

Nick Salemi, spokesper­son for the MDC, said delays in the drilling process set back con­struc­tion of the water pump sta­tion. He said the pump sta­tion could not begin con­struc­tion until the tun­nel was fin­ished.

“The tun­nel por­tion went slow­er than antic­i­pat­ed, which pushed back some of the other work,” Salemi said. “The pump sta­tion is in con­struc­tion right now.” The sta­tion will trans­port the stored waste and stormwa­ter upwards and across a road to the Hartford Water Pollution Treatment Facility. Upon treat­ment, the cleaned water will be released into the Connecticut River.

Negrelli said the pump station’s orig­i­nal planned com­ple­tion date of July 2026 may may be pushed later.

“We’re deal­ing with some delays with some elec­tri­cal equip­ment,” Negrelli said while show­ing jour­nal­ists the pump site in April. “So we’re think­ing about the late sum­mer or fall of 2026.”

Salemi said the pump sta­tion relies on physics to move the water upwards. “The whole thing works on grav­i­ty,” he said. “There’s not a lot of elec­tric­i­ty to get it 200 feet to the plant. The pump sta­tion pumps the water up across the street to the treat­ment plant.”

Construction of the pump sta­tion is being car­ried out by the engi­neer­ing com­pa­ny Arcadis, which has done work for other MDC projects. Greg Bazydola, Arcadis project man­ag­er for the pump sta­tion, said the work bal­ances fac­tors like automa­tion, pre­vent­ing excess water pres­sure buildup, and avoid­ing excess humid­i­ty, which can dam­age equip­ment.

Two shafts in that sta­tion extend under­ground to meet the pump. The first shaft was where the tun­nel drilling began with a crane low­er­ing IRIS to the nec­es­sary depth. Now that the tun­nel itself has been dug, this shaft will be repur­posed to screen large solids and grit from water stored in the tun­nel.

“You want to pro­tect those pumps that are down there from big debris so it doesn’t wear any­thing,” Bazydola said.

Eventually, more waste from the Franklin Avenue area of South Hartford will also flow into this pump sta­tion. Those con­duits have yet to built. That project is called Contract Four, also called the East Conduits. The Franklin Avenue con­duits do not need to be fin­ished for the tun­nel to work.

TOP IMAGE: At the future pump site, a shaft goes down 200 feet to meet the end of the waste tun­nel. Photo by Christine Woodside