Asbury Manor-CS090112
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Ken Griffin - Re: Fwd: Fw: Large volume of water in drainage - Asbury Manor
From: Glenn Hollowell
To: Ken Griffin
Date: 1/12/2009 12:47 PM
Subject: Re: Fwd: Fw: Large volume of water in drainage - Asbury Manor
Ken,
This "blowoff" was installed by Utility Ops personnel in order to bring up the chlorine residual in this area of
town. It was turned on the Monday before Thanksgiving. We have been struggling with chlorine residuals in this
part of town and other areas. They have been monitoring this area on a weekly basis. Based upon the
discussions that I had with Utility Ops. employees this morning, we are finally starting to see a good, consistent
chlorine residual in this area. As you are aware, we are required to keep at least a 0.5 ppm chlorine residual in
the water system at all times. This area has been giving us residual problems since September. For the last
week or so, the residual in this area has been just above a 1.0 ppm. The maximum residual that we can have in
the system is a 4.0 ppm. We feel confident that the residual should remain good the rest of the year. I have
instructed Ernest to go ahead and remove this blowoff for the remainder of the season. He stated that he was
going to continue to monitor the area. Now that the residual in the area seems to have stabilized above a 1.0
ppm, any additional flushing required can probably be handled on an "as needed" basis utilizing fire hydrants.
As I stated earlier, we have been struggling with chlorine residuals in various parts of town since
September. This year, we have had to flush quite a bit more than we normally would. This has been one of
those "bad years" for residual problems. It seemed like it took the water source a long time to cool off this year.
Cold water temperatures will hold a chlorine residual much longer than warmer temperatures. With the limited
number of personnel we currently have, this blowoff was installed in this manner so that we would not have to
have Utility Ops employees flushing fire hydrants most everyday in this area. Using this type of setup enables us
to leave the blowoff unmanned and still be able to flush the area. By installing a meter on the blowoff, we are
able to accurately record how much water was flushed for our monthly reports.
During November, we flushed 8.3 MG of water in order to keep our chlorine residual legal. During November of
2007, we only had to flush 2.4 MG. This past October, we flushed 14.1 MG for residual purposes; but, only 4.9
MG during October of 2007. The meter that we installed for this blowoff only has 372,000 gallons registered on
it at this time. That equates to about 7600 gallons per day that was flushed down the channel. The meter was
running for 49 days. Normally we use fire hydrants to flush the water system. We set the fire hydrant to put out
approximately 1500 gallons per minute when we flush. The water running down the channel per day equates to
about 5 minutes worth of flushing from a fire hydrant. On average, fire hydrants are flushed for 15 to 20
minutes a time. This is somewhere between 23,000 to 30,000 gallons at every flush. Before this blowoff was
installed, we were having to flush this area 2 or 3 times per week at multiple locations. We were probably
flushing at least 100,000 gallons per day or 200,000 to 300,000 gallons per week just in this part of town. Since
the blow off was installed, we have not had to flush through a hydrant in this area. I know it sounds crazy, but
we have actually been saving water by using this method of flushing. This method of flushing has the added
benefit of flushing for 24/7 instead of a fifteen or twenty minute period twice a week. Based upon the residual
numbers that we have been getting, we will probably only have to flush this area once per month using a
hydrant. This should last until the water starts to warm up again this Spring. If we continue to use this method
of flushing, we will try to be more discreet with where it is installed in the future. I believe Mr. Kingsbury may
have misread the meter when he made his observation. I believe the meter was putting out 5.5 gpm instead of
55 gpm.
I hope this helps clear up the confusion over this matter. Let me know if you need any further information.
Thanks,
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Glenn D. Hollowell, P.E.
Assistant Director of Public Works
972-462-5150
ghollow@ci.coppell.tx.us
>>> Ken Griffin 1/12/2009 8:35 AM >>>
>>> Clay Phillips 1/11/2009 3:47 PM >>>
Ken,
Any word yet on what this might be....see below. Thanks.
Clay
file://C:\Documents and Settings\radloo\Local Settings\Temp\XPgrpwise\496B3BFACity...12/18/2009