{"id":275,"date":"2025-06-03T18:55:56","date_gmt":"2025-06-03T22:55:56","guid":{"rendered":"https:\/\/digitaljournalism.uconn.edu\/hartford-north-end-chronic-flooding-sewage\/?p=275"},"modified":"2025-07-02T12:41:47","modified_gmt":"2025-07-02T16:41:47","slug":"tunnel-will-hold-waste-from-17-sewage-overflow-points","status":"publish","type":"post","link":"https:\/\/digitaljournalism.uconn.edu\/hartford-north-end-chronic-flooding-sewage\/2025\/06\/03\/tunnel-will-hold-waste-from-17-sewage-overflow-points\/","title":{"rendered":"Tunnel Will Hold Waste from 17 Sewer Overflow Points"},"content":{"rendered":"\n
\n

By Elijah Polance
UConn Journalism<\/strong><\/p>\n<\/blockquote>\n\n\n\n

Reducing com\u00adbined sewer over\u00adflows is a time-con\u00adsum\u00ading and expen\u00adsive endeav\u00ador for the agency that man\u00adages Hartford\u2019s sewage treat\u00adment. The Metropolitan District Commission set\u00adtled on a solu\u00adtion not used any\u00adwhere else in Connecticut: stor\u00ading untreat\u00aded waste inside a giant tun\u00adnel.<\/p>\n\n\n\n

In 2016, the MDC signed a con\u00adtract autho\u00adriz\u00ading the cre\u00adation of this tun\u00adnel, called the South Hartford Conveyance and Storage Tunnel. The tun\u00adnel will help the MDC com\u00adply with the con\u00adsent order with Connecticut\u2019s Department of Energy and Environmental Protection, requir\u00ading it to cor\u00adrect pol\u00adlu\u00adtion dat\u00ading to the mid-1990s. The tun\u00adnel was planned to begin hold\u00ading back waste oper\u00adate in 2023, but delays have pushed that to 2026.<\/p>\n\n\n\n

The tun\u00adnel will store excess stormwa\u00adter and waste\u00adwater that ends up in com\u00adbined sewer sys\u00adtems dur\u00ading heavy rain\u00adfall. The pre\u00adcip\u00adi\u00adta\u00adtion over\u00adloads these sys\u00adtems, caus\u00ading untreat\u00aded sewage to drain into pub\u00adlic water\u00adways and back\u00adflow into res\u00adi\u00addents\u2019 homes.<\/p>\n\n\n\n

Specifications from the MDC state the tun\u00adnel is four miles long and 200 feet below the ground. It has a diam\u00ade\u00adter of 18 feet and can store 41.5 mil\u00adlion gal\u00adlons of water.<\/p>\n\n\n\n

\u201cA foot\u00adball field is 360 feet long, 160 feet wide,\u201d said Susan Negrelli, the MDC\u2019s direc\u00adtor of engi\u00adneer\u00ading and plan\u00adning. \u201cSo pic\u00adture that with about 100 feet of water on it. That\u2019s 42 mil\u00adlion gal\u00adlons.\u201d<\/p>\n\n\n\n

The buried stor\u00adage tun\u00adnel begins in West Hartford, by Talcott Road, and ends in the South Meadows area of Hartford, across Brainard Road from the Hartford Water Pollution Control Facility.<\/p>\n\n\n\n

The tun\u00adnel will main\u00adly elim\u00adi\u00adnate com\u00adbined sewer over\u00adflows in south\u00adern Hartford, espe\u00adcial\u00adly 10 of the CSOs that over\u00adflow into the South Branch of the Park River and seven oth\u00aders that flow into Folly Brook and then into Wethersfield Cove. The tun\u00adnel will also take in water from sur\u00adround\u00ading towns includ\u00ading West Hartford, Newington and Wethersfield, said Nick Salemi, spokesper\u00adson for the MDC.<\/p>\n\n\n

\n
MDC Director of Engineering Susan Negrelli showing a map in Hartford, Connecticut, Friday March 28, 2025. Photo by Julianna D\u2019Addona<\/p>\n\" data-large-file=\"https:\/\/digitaljournalism.uconn.edu\/hartford-north-end-chronic-flooding-sewage\/files\/2025\/04\/IMG_6060-1024x768.jpg\" src=\"http:\/\/digitaljournalism.uconn.edu\/hartford-north-end-chronic-flooding-sewage\/files\/2025\/04\/IMG_6060-1024x768.jpg\" alt class=\"wp-image-122\" style=\"object-fit:cover\" srcset=\"https:\/\/digitaljournalism.uconn.edu\/hartford-north-end-chronic-flooding-sewage\/files\/2025\/04\/IMG_6060-1024x768.jpg 1024w, https:\/\/digitaljournalism.uconn.edu\/hartford-north-end-chronic-flooding-sewage\/files\/2025\/04\/IMG_6060-300x225.jpg 300w, https:\/\/digitaljournalism.uconn.edu\/hartford-north-end-chronic-flooding-sewage\/files\/2025\/04\/IMG_6060-150x113.jpg 150w, https:\/\/digitaljournalism.uconn.edu\/hartford-north-end-chronic-flooding-sewage\/files\/2025\/04\/IMG_6060-768x576.jpg 768w, https:\/\/digitaljournalism.uconn.edu\/hartford-north-end-chronic-flooding-sewage\/files\/2025\/04\/IMG_6060-1536x1152.jpg 1536w, https:\/\/digitaljournalism.uconn.edu\/hartford-north-end-chronic-flooding-sewage\/files\/2025\/04\/IMG_6060-2048x1536.jpg 2048w, https:\/\/digitaljournalism.uconn.edu\/hartford-north-end-chronic-flooding-sewage\/files\/2025\/04\/IMG_6060-1200x900.jpg 1200w, https:\/\/digitaljournalism.uconn.edu\/hartford-north-end-chronic-flooding-sewage\/files\/2025\/04\/IMG_6060-1980x1485.jpg 1980w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\">
MDC Director of Engineering Susan Negrelli shows a map of the tun\u00adnel\u2019s route through Hartford on March 28, 2025. Photo by Julianna D\u2019Addona<\/em><\/figcaption><\/figure>\n<\/div>\n\n\n

Negrelli said the MDC decid\u00aded to build the tun\u00adnel in south\u00adern Hartford because of the con\u00adsent order require\u00adment to elim\u00adi\u00adnate CSOs to near\u00adby bod\u00adies of water, CSO issues in West Hartford, and the prox\u00adim\u00adi\u00adty to the Hartford WPCF. She called it the \u201clog\u00adi\u00adcal start\u00ading point.\u201d<\/p>\n\n\n\n

\u201cThis is where the plant is too, so the tun\u00adnel ends at the plant,\u201d Negrelli said. \u201cSo any\u00adthing you\u2019re going to build onto that, you can go fur\u00adther into the sys\u00adtem as you may.\u201d<\/p>\n\n\n\n

According to Negrelli, the tun\u00adnel project involved five con\u00adstruc\u00adtion con\u00adtracts that includ\u00aded relo\u00adcat\u00ading util\u00adi\u00adties, bor\u00ading under\u00adground to build the main tun\u00adnel and shafts, build\u00ading a sta\u00adtion to pump the waste to the sewage treat\u00adment plant, and cre\u00adat\u00ading con\u00adduits for more waste from the east and west.<\/p>\n\n\n\n

The drilling for the tun\u00adnel began in 2019 and was car\u00adried out with a \u201chard rock tun\u00adnel bor\u00ading machine\u201d built in Germany and known as ISIS. The drilling took three years, fin\u00adish\u00ading in 2022.<\/p>\n\n\n\n

The pump sta\u00adtion will pump the stored waste to the Hartford WPCF. Because the tun\u00adnel runs slight\u00adly down\u00adhill from West Hartford to this point, grav\u00adi\u00adty will Negrelli said the pump sta\u00adtion relies on grav\u00adi\u00adty to get the water mov\u00ading up 200 feet to get treat\u00aded.<\/p>\n\n\n\n

The con\u00adduits are a series of pipes that will allow water to descend 200 feet from sewer sys\u00adtems to the tun\u00adnel with\u00adout let\u00adting too much water pres\u00adsure build.<\/p>\n\n\n\n

Salemi said that the tun\u00adnel will not become less use\u00adful as the MDC sep\u00ada\u00adrates com\u00adbined sewer sys\u00adtems through\u00adout Hartford. He said that because the process will take a long time, and because excess rain\u00adfall can be an issue regard\u00adless of the sewer sys\u00adtem, it will remain valu\u00adable.<\/p>\n\n\n\n

\u201cIt\u2019s help\u00adful to deal with the storms, it\u2019s not going to be we build it and then \u2018Why did we build this, we don\u2019t need it any\u00admore,\u2019\u201d Salemi said. \u201cIt\u2019s part of the sys\u00adtem as the way to deal with it.\u201d<\/p>\n\n\n\n

Graham Stevens, Chief of the Bureau of Water Protection and Land Reuse at DEEP, believes the tun\u00adnel is a valu\u00adable short-term solu\u00adtion, but does not solve the root of the prob\u00adlem.<\/p>\n\n\n\n

\u201cTunnels get real\u00adly com\u00adpli\u00adcat\u00aded, real\u00adly expen\u00adsive, and ulti\u00admate\u00adly, although it\u2019s a solu\u00adtion to CSOs, you\u2019re still not get\u00adting to the core issue, which is the fact that you\u2019ve got one pipe,\u201d Stevens said.<\/p>\n\n\n\n

According to MDC tun\u00adnel plans,<\/a> the need to sep\u00ada\u00adrate sys\u00adtems was taken into account while plan\u00adning CSO elim\u00adi\u00adna\u00adtion in Hartford.<\/p>\n\n\n\n

In the past, there were pro\u00adpos\u00adals for addi\u00adtion\u00adal tun\u00adnel projects to help north\u00adern Hartford. But the MDC opted for sep\u00ada\u00adra\u00adtion instead, because a tun\u00adnel would be logis\u00adti\u00adcal\u00adly chal\u00adleng\u00ading because of the dis\u00adtance to the Hartford WPCF, would not refur\u00adnish the out\u00addat\u00aded sewer sys\u00adtems that still need replac\u00ading and could end up cost\u00ading more.<\/p>\n\n\n\n

\n\n\n\n

TOP IMAGE: This illus\u00adtra\u00adtion from the Metropolitan District Commission\u2019s plan\u00adning brochure shows the route of the waste tun\u00adnel under\u00adneath bedrock, head\u00ading slight\u00adly down\u00adhill for 4 miles from West Hartford to near the sewage treat\u00adment plant in the South Meadows area of Hartford.<\/em><\/p>\n","protected":false},"excerpt":{"rendered":"

By Elijah PolanceUConn Journalism Reducing com\u00adbined sewer over\u00adflows is a time-con\u00ad\u00adsum\u00ading and expen\u00adsive endeav\u00ador for the agency that man\u00adages Hartford\u2019s sewage treat\u00adment. The Metropolitan District Commission set\u00adtled on a solu\u00adtion not used any\u00adwhere else in Connecticut: stor\u00ading untreat\u00aded waste inside a giant tun\u00adnel. In 2016, the MDC signed a con\u00adtract autho\u00adriz\u00ading the cre\u00adation of this\u2026<\/p>\n","protected":false},"author":1110,"featured_media":274,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"wp_typography_post_enhancements_disabled":false,"ngg_post_thumbnail":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[8],"tags":[17],"class_list":["post-275","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-the-tunnel","tag-the-tunnel"],"jetpack_featured_media_url":"https:\/\/digitaljournalism.uconn.edu\/hartford-north-end-chronic-flooding-sewage\/files\/2025\/05\/Tunnel-geologic-profile-from-MDC.png","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/digitaljournalism.uconn.edu\/hartford-north-end-chronic-flooding-sewage\/wp-json\/wp\/v2\/posts\/275","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/digitaljournalism.uconn.edu\/hartford-north-end-chronic-flooding-sewage\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/digitaljournalism.uconn.edu\/hartford-north-end-chronic-flooding-sewage\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/digitaljournalism.uconn.edu\/hartford-north-end-chronic-flooding-sewage\/wp-json\/wp\/v2\/users\/1110"}],"replies":[{"embeddable":true,"href":"https:\/\/digitaljournalism.uconn.edu\/hartford-north-end-chronic-flooding-sewage\/wp-json\/wp\/v2\/comments?post=275"}],"version-history":[{"count":13,"href":"https:\/\/digitaljournalism.uconn.edu\/hartford-north-end-chronic-flooding-sewage\/wp-json\/wp\/v2\/posts\/275\/revisions"}],"predecessor-version":[{"id":1186,"href":"https:\/\/digitaljournalism.uconn.edu\/hartford-north-end-chronic-flooding-sewage\/wp-json\/wp\/v2\/posts\/275\/revisions\/1186"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/digitaljournalism.uconn.edu\/hartford-north-end-chronic-flooding-sewage\/wp-json\/wp\/v2\/media\/274"}],"wp:attachment":[{"href":"https:\/\/digitaljournalism.uconn.edu\/hartford-north-end-chronic-flooding-sewage\/wp-json\/wp\/v2\/media?parent=275"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/digitaljournalism.uconn.edu\/hartford-north-end-chronic-flooding-sewage\/wp-json\/wp\/v2\/categories?post=275"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/digitaljournalism.uconn.edu\/hartford-north-end-chronic-flooding-sewage\/wp-json\/wp\/v2\/tags?post=275"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}