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A pump at left directs groundwater-augmented wastewater through a line left to right, from the north to the south side of closed- off Colorado Avenue between 30th and 31st streets May 11. Photo looks east. The street at right is Golden Lane. The 3000 block of the avenue is likely to remain closed through the week, but could reopen sooner if there's no new rainfall and the groundwater level drops enough, according to a Colorado Springs Utilities spokesperson.
Westside Pioneer photo

Groundwater infiltration concerns force Utilities to continue closure of West Colorado's 3000 block

       Because of high groundwater from about a week of steady rainfall, Colorado Avenue between 30th and 31st streets has been closed since May 9 to traffic in both directions and could stay that way for the rest of this week.
       Colorado Springs Utilities spokesperson Steve Berry said the problem is that the water table in that location, which is normally high, rose so much from the rain that it began infiltrating the underground wastewater system.
       If that were allowed to continue, the groundwater combined with the wastewater in the pipes could exceed capacity and surcharge the polluted liquid into the street.
       To avert this scenario, Utilities has set up a “daisy-chain” of pumps to relocate the excess wastewater/groundwater south of the avenue to a “lower point on the wastewater system that can handle it,” he explained.
       But the side effect is that the water can only be moved through a large bypass hose laid across the avenue, which requires that the traffic there be closed in both directions, he added.
       Although wastewater is moved through a closed system, high groundwater can infiltrate through joints or at manholes. It's at the manholes that any surcharging can occur, he noted.
       He did clarify that the health threat is not considered extremely dangerous, in that the “volume of water dilutes it [the combined liquids] to a great extent.” But the loss of any amount of wastewater is still undesirable, and could even lead to Utilities being fined by its oversight agencies, he pointed out.
       Berry said this is the first time such a problem has occurred in the city since the heavy rains of 1999. At that time, the issue was “system-wide,” but this time it's confined to the one block of the avenue.
       Compounding the naturally high water table is a “velocity” issue, he noted, meaning that the flow moves underground with relative speed to that block because it's at the base of the gradual hill up through Pleasant Valley.
       Berry couldn't predict with certainty how long the avenue will have to stay closed between 30th and 31st. Traffic is being detoured onto Pikes Peak Avenue.
       “If things stay relatively dry, we could be out by the end of week,” he said. “If we can get out of there sooner, we will. But if there's any risk, we will have to stay and keep pumping.”
       Berry also requested that homeowners using sump pumps for flooded basements not connect them to the wastewater system because that would just increase the excess-capacity issue. They need to be connected to storm drains, he said.

Westside Pioneer article
(Posted 5/11/15, updated 5/13/15; Projects: Utilities)

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