NL Cypress-CS110720
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Leslie Henderson - Re: Cypress Waters - Force Main Connection
From:Ken Griffin
To:marty.paris@kimley-horn.com
Date:7/20/2011 3:28 PM
Subject:Re: Cypress Waters - Force Main Connection
CC:brad.moss@kimley-horn.com; BWalker@Billingsleyco.com; james.bryan@kimley-horn.com;
Leslie Henderson
Marty
Your inverted siphon solution doesn't appear to address two elements typically associated with inverted siphons:
1) Most inverted siphons have multiple pipes to handle the variation in flow throughout the day to ensure that
the 3 ft/s velocity is maintained; 2) There needs to be an inlet structure on the east side of Belt Line (near station
2) to provide maintenance access. Inverted siphons will clog up and need to be cleaned periodically. We just
eliminated one because we were cleaning it out weekly to maintain flow.
The other issue that needs to be addressed is that you need to coordinate your design with Pacheco Koch, who is
designing the Lesley Retail Tract at Dividend Drive. Their plans show a proposed 12" SS line on the east side
of Belt Line that could be in conflict with your proposed 10" FM. Both parties need to work together to try to
come up with one crossing of Belt Line to handle flows from both developments.
Ken Griffin, P.E.
>>> <marty.paris@kimley-horn.com> 7/7/2011 8:42 AM >>>
Ken,
We have attached an exhibit of the 10-inch force main profile to illustrate the hydraulics of the system under the following
scenarios:
1.Phase 1 Development - 1 pump running at approximately 750 gpm (1 MGD) with 10-inch velocity at 3.0 ft/s
2.Phase 2 Development - 2 pumps running at approximately 1,250 gpm (1.8 MGD) with 10-inch velocity at 5.1 ft/s
In Phase 1, the force main will actually go into gravity flow past the high point at Station 19+90 with a portion of the main
flowing partially full. At the connection to the 12-inch line in Belt Line, the 10-inch will also be flowing by gravity and
operate as an inverted siphon.
In Phase 2, the pumps have to pump to Station 2+06 where the 10-inch line will go into gravity flow at the high point on the
east side of Belt Line and operate as an inverted siphon.
Since the connection at Belt Line will operate as an inverted siphon flowing by gravity, we are proposing to connect to the
existing 12-inch line as shown in the attached exhibit labeled Option 3. We also sketched a couple of other options that
we discussed in our meeting, but Option 3 is our recommendation.
Please review and let us know your thoughts. Thank you.
Marty S. Paris, PE
Kimley-Horn and Associates, Inc.
12700 Park Central Drive, Suite 1800
Dallas, Texas 75251
972-770-1300 (main) 972-239-3820 (fax)
972-776-1732 (direct)
marty.paris@kimley-horn.com
file://C:\Documents and Settings\lhenderson\Local Settings\Temp\XPgrpwise\4E26F42EC...7/20/2011