Re water quality issues (2)488.54'
On May 13, 2014, at 3:34 PM, "Keith Marvin" <KMarvin@coppelltx.gov
<mailto:KMarvin@coppelltx.gov> > wrote:
What is our current water surface elevation?
From: Suarez, Michael [mailto:msuarez@walshgroup.com]
Sent: Tuesday, May 13, 2014 2:56 PM
To: John Rutledge; Keith Marvin
Subject: RE: water quality issues
No, the lake did not rise last night due the rain.
The rpms can be lowered on the pump so that the flow can be
reduced. If we were to decrease the pumping rate it will cause an
increase in cost that will have to be dealt with as well. DWU has
control of the gates that release water from Grapevine and Lewisville,
they should have the ability to increase the release from the lakes to
help dilute the water. They won’t really be wasting any water, they
just won’t get any of the “free” water from North Lake.
From: John Rutledge [mailto:JLR@freese.com]
Sent: Tuesday, May 13, 2014 2:34 PM
To: Suarez, Michael; Keith Marvin
Subject: water quality issues
I talked with Ken Delregno with DWU. I asked several questions
wanting to get an understanding so we could figure what, if any,
adjustments are needed, He expressed concerns about the hardness,
chlorides and fluorides. Says it has been going on a few weeks and took
him and his a staff a while to realize the possible linkage with North
lake. He said that the chlorides are what some clients are concerned
about, particularly hospitals. They can treat it, but they don’t like it
and have been complaining to him. He said they are doing some more tests
and will likely have some results and be in a position to talk tomorrow.
He say he would most likely ask us to cut the pumping rate in half or
some other significantly reduced rate.
I checked USGS records for the last few weeks and at the gauge
at 348, flows have generally been between 100 and 200 cfs, so our
pumping has been roughly half the flow. Right now the flow on the elm
fork is up around 600 cfs at Hiway 348 so there should be considerable
dilution going on currently. It peaked at about 850 last night. I will
let you know what he says tomorrow.
It will likely be back to 200 cfs by sometime tomorrow morning..
Its clear North Lake’s chlorides are about double the natural in the
river and so we may need to work out releases as a percentage or
something.
Michael, did you get any rise in the water level from the rain?
I know you’ve pumped about 2/3 of the water. Other than the
obvious longer time, what is the impact to you and the project of a
lower pumping rate? Is it a variable speed pump that could be reduced or
is it an on/off type pump? I would like to figure out some options to
have handy when I talk to him tomorrow.
Thanks,
John
John Rutledge
Freese and Nichols, Inc.
4055 International plaza, St 200
Fort Worth, TX 76109
(817) 735-7284
jlr@freese.com <mailto:jlr@freese.com>
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