MAC to Lower
Water Table 20-feet;
Lake Nokomis 4.6-foot Drawdown Expected
unveils draft groundwater study
Tell them NO!
Metropolitan Airports Commission (MAC) construction for
the new north-south runway includes plans for a sub-runway tunnel at the
north end, by Mother Lake. Recently MAC filled 6.5 acres of Mother (formerly
Mud) Lake wetlands and raised the level of the dam four inches.
MAC wanted to begin construction last April. The tunnel would connect
a public street on the west side of the runway with a new cargo area on
the east side.
"Competent" bedrock would not be breached according to plans. Competent
bedrock is not simply where rock meets soil. Any rock that can be removed
by hydraulic truck hammer is not considered "competent."
The planned 20-foot drawdown would require pumping out 4,250 gallons per
minute for approximately 15 months. It is "likely" that area lakes are
hydraulically connected to the underlying groundwater and would be effected
by the lowering of the aquifer. Kelton Barr, hydro-geological consultant
to the Minnehaha Creek Watershed District (MCWD) estimated drawdown effects
in his draft report to be:
Name and Drawdown (in feet)
Lake Nokomis 4.6
Diamond Lake 4.3
Legion Lake 5.4
Taft Lake 6.1
Mother Lake 6.3
Rare black ash seeps in Minnehaha Gorge, fed by water percolating through
limestone fractures, appear to be threatened by this project. "These (drawdown)
effects will also likely affect other wetlands in the area north, northwest,
and west of the airport," Barr states.
Since much of south Minneapolis is built on wetlands neighborhood residents
are wondering if their homes might settle and buckle as happened with
dewatering for I-35W. There is no comprehensive hydrology study. At minimum,
a ground penetrating radar study could identify fractures in the bedrock
indicating water passages. Barr says such a study is "mostly likely do-able,"
since it is relatively cheap and fast.
There is no mention of effects on Minnehaha Creek or on the 10,000 year
old spring at Camp Coldwater, birthplace of the political state of Minnesota.
Coldwater Spring is currently used by Dakota and Anishinabe people as
a traditional sacred site for water and pipe ceremonies.
The MAC is seeking a groundwater appropriations permit from the Minnesota
Department of Natural Resources. The MAC also needs a permit from the
MCWD for erosion and sediment control on this project. MCWD’s rule
N, section 4(c) states that a project "shall not adversely effect the
water table during or after construction." Three more sub-runway tunnels
are planned, as well as an extensive LRT tunnel.
A huge portion of our state’s groundwater flows to the confluence
of the Minnesota and Mississippi rivers. This area is a waterlogged landscape
with bedrock like Swiss cheese, veins and arteries of underground water
channels meeting at the great confluence. MnDOT Hwy 55 engineer Bud Peterson
told the MCWD "there’s a lot more water there than we thought."
The airport tunnel issue is scheduled for a vote at the next regular MCWD
meeting, Thursday, June 29, 2000, 6:30 pm, at Minnetonka City Hall, Minnetonka
Blvd. (route 5, west of 494), 2nd floor in the council chambers. Also
up for a vote at this meeting is a request by MnDOT for an extension of
their Hwy 55 reroute permit.
them that you oppose their plan and that their study does not include
all relevant information. Potential pollution from the airport grounds,
that are known to be laiden with spilled jet fuel and deiceing solution
could pose a serious problem if water is drained through the area.
Watershed District www.minnehahacreek.org
Minnesota Department of Natural Resources www.dnr.state.mn.us/
acting Director of DNR Waters is Kent Lokkesmoe (651) 296-4800
Camp Coldwater Coalition
contact: Tom (BudTBum@TCInternet.net)