WA0501-CS050718 Ken Griffin - New Development Fire Flow Analysis
From: "Angela Lang" <ALang @BHCLLP.COM>
To: <kgriffin @ci.coppell.tx.
Date: 7/18/2005 4:59 PM
Subject: New Development Fire Flow Analysis
CC: "Doug Showers" <DShowers @BHCLLP.COM>
Mr. Griffin:
We have re- analyzed the water system with the updated 12 -inch water line along Meadowcreek and with the new
development southeast of Bethel School Road and Denton Tap Road. The 23 homes will impact the system with a load of
0.028 MGD at max day and 0.0596 MGD at max hour.
With the assumption of 1500 gpm (2.16 MGD) required at two fire hydrants (750 gpm each) at any given time, the results for
flows and pressures are as follows:
At Max Day prior to the new development:
1. In the general area the fire flows satisfy the 2.16 MGD for 2 fire hydrants.
2. The Residual Pressures in the area are in the range of 60 -74 psi.
3. Minimum Zone Pressure in the system is approximately 48 psi at a dead end water line along Bethel Rd west of Royal Ln.
At Max Day without Proposed 8" WL connected to Meadowcreek WL:
1. In the new neighborhood some fire flows are low in the range of 1.54 -1.59 MGD; a 29% decrease of flow due to the
development.
2. Some Residual Pressure in the new development are in the range of 33 -35 psi; the rest are in the range of 53 -74 psi; a
45% decrease of pressure due to the development.
3. Minimum Zone Pressure in the system is 35 psi in the new neighborhood.
4. The pressure is low at some points because the only source of water is the 6 -inch water line and the
only loop into the system; in essence the whole neighborhood is in a dead end.
At Max Day with Proposed 8" WL connected to Meadowcreek WL:
1. Fire flows to the new development are in the range of 2.16 - 2.23 MGD; a 40% increase of flow.
2. Residual Pressures in the new development are in the range of 60 -74 psi; a 82% increase of pressure.
3. Minimum Zone Pressure in the system is approximately 48 psi at a dead end water line along Bethel Rd west of Royal Ln.
At Max Hour prior to the new development:
1. In the general area some fire flows are low in the range of 1.59 -1.66 MGD.
2. Some Residual Pressures in the area are low in the range of 33 -35 psi; the rest are in the range of 47 -69 psi. Refer to the
Water Distribution System Master Plan Report: at J -788 the pressure is 64.98 and drops to 53.40 due to the fire flow.
3. Minimum Zone Pressure in the system is 35 psi in the general area.
4. The pressure is low at some points because the only source of water is the 6 -inch water line and the
only loop into the system; in essence the whole neighborhood is in a dead end.
At Max Hour without Proposed 8" WL connected to Meadowcreek WL:
1. In the new neighborhood some fire flows are low in the range of 1.55 -1.61 MGD; a 3% decrease of flow due to the new
development.
2. Some Residual Pressure in the new development are in the range of 32 -35 psi; the rest are in the range of 46 -69 psi.
3. Minimum Zone Pressure in the system is 35 psi in the new neighborhood.
At Max Hour with Proposed 8" WL connected to Meadowcreek WL:
1. Fire flows to the new development are in the range of 2.16 - 2.32 MGD; a 39% increase of flow
2. Residual Pressure in the new development are in the range of 55 -69 psi; a 72% increase of pressure
3. Minimum Zone pressure in the system is approximately 46 psi at a dead end water line along Bethel Rd west of Royal Ln.
*Although TCEQ's minimum requirement is 35 psi, it is our experience that at pressures lower than 40 psi, there are larger
amount of complaints about the lower water pressure.
We are available at your convenience to discuss this analysis further.
Sincerely,
Angela Lang, E.I.T.
Birkhoff, Hendricks, & Conway, L.L.P.
7502 Greenville Ave., #220
Dallas, TX 75231
(214) 361 -7900 phone
(214) 361 -0204 fax
alang @bhcl,com