Are we to be surprised? Here we go again? We've been here before? Ad nauseum! >Date: Wed, 14 Feb 2001 02:13:47 -0600 (CST) >From: [EMAIL PROTECTED] >To: [EMAIL PROTECTED] >Subject: Star Tribune Article >Sender: [EMAIL PROTECTED] > >This article from The Star Tribune has been sent to you by annie. > >Airport tunnel changes require additional groundwater pumping >http://www.startribune.com/viewers/qview/cgi/qview.cgi?story=83557281&templ ate=metro_a_cache > > > >Officials at Minneapolis-St. Paul International Airport said Tuesday that they want to change the way they reduce the need for pumping ground water from two tunnel construction sites. The change would require revision of last summer's agreement with local and state environmental agencies to prevent potential lowering of nearby lake levels, including Lake Nokomis. > >Under the current method, called jet grouting, contractors inject concrete into soil around the tunnel site, forming a barrier that keeps water from seeping in. The technique is being used around a service tunnel beneath a new runway. But it won't work for two shorter airport tunnels, said Gary Warren, director of airside development for the Metropolitan Airports Commission (MAC). Tests have shown that stable soils under the shorter tunnels are deeper and more variable than expected, he said. > >He recommended using more conventional barriers instead to prevent seepage and reduce pumping requirements. One alternative is to install an impermeable sheet such as those used in landfills. Another is to drive steel pilings into the earth and lay a concrete floor beneath the tunnel. Unlike the jet grouting technique, either of those options would require ground-water pumping for up to 40 days while these materials are installed. The work on the two tunnels would not be done simultaneously, to reduce the impact, he said. > >The Minnehaha Creek Watershed District must approve the changes before issuing permits for the project, and Warren said, "I believe they're comfortable with this approach." > >The MAC's Planning and Environment Committee approved the recommendation Tuesday. The full commission will consider it next Wednesday. > >-- Dan Wascoe Jr. > Annie Young Ward 6 - East Phillips in Minneapolis Citywide at-large Park Board Commissioner Working to build a sustainable community _______________________________________________ Minneapolis Issues Forum - Minnesota E-Democracy Post messages to: [EMAIL PROTECTED] Subscribe, Unsubscribe, Digest option, and more: http://e-democracy.org/mpls
