{"id":1267,"date":"2021-11-08T05:00:00","date_gmt":"2021-11-08T05:00:00","guid":{"rendered":"https:\/\/www.trccompanies.com\/insights\/overhauling-oroville-the-amazing-push-to-repair-the-tallest-dam-in-the-united-states\/"},"modified":"2024-12-13T10:25:28","modified_gmt":"2024-12-13T10:25:28","slug":"overhauling-oroville-the-amazing-push-to-repair-the-tallest-dam-in-the-united-states","status":"publish","type":"news-and-insights","link":"https:\/\/www.trccompanies.com\/fr\/insights\/overhauling-oroville-the-amazing-push-to-repair-the-tallest-dam-in-the-united-states\/","title":{"rendered":"Overhauling Oroville: The Amazing Push to Repair the Tallest Dam in the United States"},"content":{"rendered":"\n\n
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The Oroville Dam in Northern California is the highest in the country at 770 feet \u2013 four stories taller than the more celebrated Hoover Dam \u2013 but few outside the Golden State had ever heard of it before February of 2017.<\/p>\n

That\u2019s when the dam made headlines worldwide after its primary and emergency spillways suffered significant damage just days apart, prompting public safety officials to evacuate thousands of downstream residents for fear the emergency spillway would let go. Video footage of the hillside next to the main spillway being washed away<\/a> under a punishing torrent of water aired for days on newscasts across the globe.<\/p>\n

In an amazing turn-around, however, construction crews last week put the finishing touches on the second phase of the Lake Oroville Spillways Emergency Recovery Project<\/a>, a massive $1.1 billion overhaul of the 50-year-old dam, meeting a key November 1 deadline as California braces for its rainy season.<\/p>\n

\u201cMore than 700 construction workers, many of them from Butte County and other parts of Northern California, literally worked day and night to make incredible progress during the 2018 construction season,\u201d said Tony Meyers<\/a>, the project\u2019s manager.<\/p>\n

TRC has played an integral role in the ambitious endeavor, providing construction management support and performing contract administration, claims support, scheduling review, blasting inspection and round-the-clock field inspections (including drone documentation) for the California Department of Water Resources \u2013 all to help bring a major infrastructure project to fruition in less than two years.<\/p>\n

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\u201cIt\u2019s incredible what the department did in a very short amount of time,\u201d said Agnes Weber, senior vice president of TRC\u2019s Construction Services West group. \u201cThe manpower, the materials \u2013 plus they had an incredible safety record with just a small number of reportable incidents.\u201d<\/p>\n<\/blockquote>\n

TRC has been on-site from the start. Staff from Vali Cooper & Associates \u2013 acquired by TRC over the summer \u2013 were among the first called in under an on-call construction management contract the company has held with DWR since 2008.<\/p>\n

\u201cI remember being out there just a few days after repair work started,\u201d said Weber. \u201cIt was 2 a.m. and it was raining, cold and wet. It looked like a Mad Max movie. There was heavy equipment and dredging taking place in the river and bright lights lighting up the night. It was amazing.\u201d<\/p>\n

Just 20 months later, the chaotic work site has been replaced by a new reinforced spillway chute designed to withstand the onslaught of water from above as well as new emergency spillway buttressed by a new retaining wall and featuring a staircase-like splash pad to prevent erosion. Fantastic drone footage released by DWR<\/a> shows the before and after.<\/p>\n <\/div>\n <\/div>\n\n <\/div>\n <\/div>\n<\/section>\n\n\n\n\n

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What Happened<\/h2>\n

In 2017, Northern California was hit by record rainfalls<\/a> that caused water levels in Lake Oroville to steadily rise through December and January. Then, in early February, the area got hit with 13 inches of rain in just five days.<\/p>\n

On February 7, DWR increased the outflow on the Oroville Dam\u2019s main spillway to keep up with the rising water levels. But workers quickly noticed a \u201csubstantial disturbance\u201d<\/a> in the flow of water halfway down the spillway. When they closed the gates completely an hour later, they discovered a 250-foot gash in the spillway chute. But with the rain continuing, officials were left with no choice but to cautiously reopen the gates and closely monitor the situation.<\/p>\n

By February 11 the water level was high enough to crest the emergency spillway for the first time in the dam\u2019s history. But the heavy flow of water caused extensive erosion \u2013 erosion that was \u201crapidly advancing.\u201d Fearing catastrophe, public safety officials ordered residents of the Feather River basin below the dam to evacuate the area. Within 48 hours, 188,000 people had packed up and gotten out of harm\u2019s way.<\/p>\n

In the meantime, dam personnel were forced to crank up the flow to the main spillway to unprecedented levels. This allowed the lake\u2019s water level to slowly decrease and residents to return to their homes. But when the gates to the main spillway gates were finally closed on February 27 and officials could survey the damage, they discovered the deluge had turned the gash in the spillway chute into a 200-foot deep, 1,100-foot long chasm and washed away much of the adjacent hillside.<\/p>\n <\/div>\n <\/div>\n<\/section>\n\n\n\n\n

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