DDW-2025-003155

J. Paul Wright <[e-mail]>
Sand Hollow Well #7 - Pump House and well equipping comments (File #13422)
4 messages
J. Paul Wright <[e-mail]>Mon, Mar 31, 2025 at 2:41 PM
To: Todd Gardner <[e-mail]>, Russ Vernon <[e-mail]>
Todd and Russ,
I have reviewed the plans for equipping Sand Hollow Well #7. I have a few comments:
1) You have described one of the pump alternatives as having the capacity to pump up to 305 gpm. Because the well
was pump tested and it stabilized at between 280 and 287 gpm, that is the maximum the well is allowed to be pumped.
So, you would have to ensure to throttle the well to only pump up to that amount. The well safe yield, as determined by
2/3 of the pump test rate will be set at about 187 gpm.
2) On Sheet 3 the plans show the head wall (pump discharge) with a #14 screen on the end of the pipe. You are only
required to have a #4 screen. A #14 works, but is much finer, so I just want to ensure that you have designed the pipe
size accounting for that tighter mesh screen if that is what you are planning.
Let me know if you have any questions.
Paul
--
J. Paul Wright, P.E. | District Engineer | Southwest Utah District
435.986.2590 (office) | 435.680.0163 (cell) | 435.986.2595 (fax)
620 S 400 E #400, St. George, UT 84770
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Russ Vernon <[e-mail]>Wed, Apr 2, 2025 at 11:33 AM
To: "J. Paul Wright" <[e-mail]>
Cc: Todd Gardner <[e-mail]>
Good morning, Paul.

Thanks for your comments.

4/2/25, 11:51 AM State of Utah Mail - Sand Hollow Well #7 - Pump House and well equipping comments (File #13422)
https://mail.google.com/mail/u/0/?ik=f3bcb897f8&view=pt&search=all&permthid=thread-a:r8087796241929237911&simpl=msg-a:r-245018161256699…1/2
1. The well will be equipped with a Variable Frequency Drive (labeled WPCP on the drawings) and the
pump will set to run normally at a speed that produces a flow of 187 gpm. System operators will be
advised of the normal flow rate and will verify frequently with the discharge flow meter.

2. The contractor will be advised of a field change to a #4 screen, instead of the #14.

Thanks again,
Russ Vernon, PE
[Quoted text hidden]

J. Paul Wright <[e-mail]>Wed, Apr 2, 2025 at 11:40 AM
To: Russ Vernon <[e-mail]>
Cc: Todd Gardner <[e-mail]>
Thanks Russ,
On comment #1, they can operate as high as the 24 hour constant test rate, which as I stated was between 280 and 287
gpm (is used 280 gpm conservatively). The safe yield that we calculate is intended to establish source capacity (peak
day demand), which the DDW uses to determine the number of Equivalent Residential Connections that can be added
with this source, so that is where the 187 gpm comes from. The main reason for my comment is that you had operational
scenarios at 290 and 305 gpm, so I wanted to make sure they weren't planning on exceeding 280 gpm, which it sounds
like they can set with the VFD. I hope that makes sense.
Paul
[Quoted text hidden]
Russ Vernon <[e-mail]>Wed, Apr 2, 2025 at 11:46 AM
To: "J. Paul Wright" <[e-mail]>
Cc: Todd Gardner <[e-mail]>
OK, Thanks, Paul.

To verify, the well can run at 280 gpm.

Thanks for the explanation on the ERC calculation.

Russ
[Quoted text hidden]
4/2/25, 11:51 AM State of Utah Mail - Sand Hollow Well #7 - Pump House and well equipping comments (File #13422)
https://mail.google.com/mail/u/0/?ik=f3bcb897f8&view=pt&search=all&permthid=thread-a:r8087796241929237911&simpl=msg-a:r-245018161256699…2/2