DDW-2025-006639

Logan,

I have reviewed the plans and water model that you sent, I have the following comments:

1) In reading through the report, it appears you use 800 gallons per day (gpd) for indoor use and
479 gpd for outdoor use for a total of 1,279 gpd peak day demand per connection. However, in
2020, a system specific peak and average day demand was determined for St George City. This
was a new requirement per the legislature several years ago and is used in place of the
demands in R309-510 for systems that have that established. The system specific peak day
demand per connection for St George is 1,534 gpd and an average demand of 765 gallons per
connection. You can find these numbers at this waterlink site:
https://waterlink.utah.gov/reports.html?systemId=1425. These should be used for setting
demands in the hydraulic model for peak day demand (Minimum 40 psi) and for peak day
demand plus fire flow (minimum 20 psi). I wasn’t aware that an official value was posted on
the referenced website. The St. George City Culinary Water Master Plan dated December 30,
2019 does list the 1,534 gpd in Table 3-19, but calls it out as a “source” sizing standard. This
number is reached by adding a 20% variation to the highest value found in July of 2017.
However, under the Hydraulic modeling approach in chapter 6 of said report it lists peak day
demands for the system in million gallons per day and states that they used the highest values
from July 2017. If you back calculated this table using the total culinary water system ERC’s
the peak day demand per ERC is the 1,279 gpd. This is why the lower number was used in the
study so that it was consistent with the peak day demand of the hydraulic modeling section
report. A revised report with the 1,534 gpd peak day demand for existing ERC’s has been
created. In the report future ERC’s were given a value of 1,048 gpd this number was given to
me by the city of St. George based on new low water requirements from the Washington
county water district.

2) I just want to clarify what the actual operational flow will be for the booster station. The
report states 195 gpm as the peak flow, but you have 1 - 150 gpm pump, 2 - 500 gpm
pumps,and 1 - 1,000 gpm pump. I assume that one of the 500 gpm pumps may be used in a
peak flow scenario, along with the 150 gpm pump. Other than that, the 1,000 and 500 gpm
pumps are primarily for fire flow. Do I understand this correctly? It was the intention that the
150 gpm would be a variable speed pump to handle all of the low flows up to 150 gpm. The
500 gpm pump, which also variable speed would cover the peaking flows. The 1000 gpm will
add to the 500 gpm to cover the fire flow. The 195 gpm as the peak flow was based off the
state code equation, this is being revised to 91.7 gpm to match the listed peak day demand
with a 2.0 peaking factor

3) Can you verify that the minimum intake pressure for the pumps is 20 psi? This is required by
rule in R309-540. The City of St. George conducted a fire flow test on June 13, 2025, at fire
hydrants near the project. Static and residual pressures of 60 psi and 52 psi respectively were
measured at the hydrant near 1384 West 2440 South and a 1600 gpm flow rate was measured
at the hydrant near 1328 West 2440 South.

4) The pump station detail on Sheet 95310-B-001 shows two air release valves. The notes say
they should be piped to the floor drain, which appears on the far right side of section B-B. The
note instead should indicate that the end of the downturned air vent has a non-corridible #14
mesh screen on the end and it cannot terminate any closer than 6 inches from the floor, not to
the drain as the note indicates. This has been revised in the latest submittal from EFI See the
Layout plan in the email.

5) The pressure gauge indicated on the suction should be capable of measuring both positive
and negative pressures. The discharge side pressure gauge can be a standard gauge. This has
been revised in the latest submittal from EFI See the Layout plan in the email.

6) I assume the generator is for backup power at the booster station, since that is required. The
generator is for back up power.

Let me know if you have any questions.

Paul