IDAHO SPRINGS, Colo. (CBS4) – Problems arising from contaminated ground water have delayed the reconstruction of a bridge on Interstate 70 near Idaho Springs.

Crews discovered lead, iron and other metals and materials in the water recently.

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“We’re stopping some construction while we figure out how to mitigate that contamination,” CDOT spokeswoman Emily Wilfong said.

The demolition of the bridge on state highway 103, which leads south from the interstate to Mount Evans, was initially delayed because of limited supplies.

The bridge is being reconstructed so a wider I-70 can fit under it. The project was supposed to take six weeks. CDOT estimates this delay could last one month and the project will be finished, at the latest, in mid-January.

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“Right now it’s looking like the project will be pushed back just a little while as we try and find the best mitigation possible for the water,” Wilfong said.

She said CDOT needs to keep lanes open on Sunday afternoons in winter to help traffic move as quickly as possible from the mountains to Denver.

“Really we’re just trying to do the work as quickly and most efficiently as possible so that skiers can get on their way, folks in Idaho Springs can get to the businesses,” Wilfong said.

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The twin tunnels expansion is still on schedule to be wrapped up by the end of the year.