DDW-2024-012427

October 22, 2024
Teresa Gray
Salt Lake City Water System
1530 South West Template
Salt Lake City, Utah 84115
Subject:Plan Approval, Package 3- City Creek WTP (TP003) Facilities Upgrade.
Temporary Exceptions to R309-525-13(2)(a) Sedimentation Detention Time, R309-525-13(c) Sedimentation Flow Through Velocity and R309-525-15(v) Dual Media Rate, Salt Lake City Water System,
System #18026, File #12496.
This Temporary Exception Expires on October 31, 2027.
Dear Teresa Gray:
The Division of Drinking Water (the Division) received the plans and specifications for the City Creek WTP (TP003) upgrade project from your consultant Steven Benchley of Brown and Caldwell
on August 06, 2024. Based on the Division staff comments and suggestions, an update on the project design was provided to the Division on October 04, 2024, along with your request for
an exception to the following rules. This project has met the conditions for receiving a plan approval.
·R309-525-13(2)(a) Sedimentation Detention Time
A minimum of four hours of detention time shall be provided. Reduced sedimentation time may be approved when equivalent effective settling is demonstrated, or multimedia filtration is
employed.
·R309-525-13(c) Sedimentation Flow- Through Velocity
The velocity through settling basins shall not exceed 0.5 feet per minute. The basins shall be designed to minimize short circuiting. Fixed or adjustable baffles shall be provided as
necessary to achieve the maximum potential for clarification.
·R309-525-15(v) Dual Media Rate
Dual media filters will be assigned a filter rate up to six gpm/sf. Generally, if the bottom fine layer consists of material having an effective size of 0.35 mm or less, a filtration
rate of six gpm/sf can be assigned.
Our understanding of the project is that the Salt Lake City Department of Public Utilities (SLCDPU) is taking a phased approach to rebuild the City Creek WTP (TP003). Depending upon
the availability of Building Resilient Infrastructure and Communities (BRIC) funds, different packages are proposed. 
Package 1 consisted of the initial phase to divert at a maximum of 4 MGD of City Creek Water via a bypass pipeline connecting the north flocculation basin to the filter building. Package
1 was approved by the Division on June 7, 2023, under file # 12494.
Package 2 improvements were completed for City Creek WTP (TP003) conversion to Direct Filtration by conversion of 2 of 4 existing filters to flocculation basins, bypass pipe of existing
flocculation and sedimentation basins and moving the disinfection compliance point of entry (POE) to downstream at Site 12 (picnic spot) to meet the proper CT. Package 2 was approved
by the Division on November 21, 2023, under file # 12496.
The Operating permits for Package 1 and Package 2 were issued by Division on July 09, 2024. The City Creek WTP is currently functioning as a Direct Filtration System.
Under further usage of BRIC funding, SLCPU has submitted Package 3 to include some of the facilities of existing City Creek WTP (TP003).
The project includes construction of a new conventional water treatment facility within the footprint of the existing flocculation and sedimentation basins to include:
Construction of all yard piping associated with the new treatment plant to make it operational.
Construction of an addition to the existing Fluoride Building.
Construction of 2 sedimentation basins.
Construction of 2 flock basins.
Construction of 6 filters.
Construction of a septic drain tank, discharge pipe, and drain field.
Modifications to the existing clarifier to include the replacement of the rake arm/motor, replacement of reclaim pumps, placement of a geodesic dome cover, construction of a vestibule
over the control cabinet, construction of new stair access to the clarifier.
Construction of a soil nail/shotcrete retaining wall on the south side of the clarifier.
Construction of piping and gates between Drying Beds 1 and 2 and Beds 2 and 3.
Construction of an infiltration gallery as part of the new perimeter drain system.
Modifications to the existing Operations Building to house a new 1,000kW generator, demolition of the existing 1,000-gallon external fuel tank, and construction of a new 3,000-gallon
external fuel tank.
Construction of rock weirs in the City Creek channel between the intake and footbridge.
Raising the creek channel embankment adjacent to the Fluoride Building.
Demolition of the existing Filter Building.
Exception request
The basis for your request for an exception to Rule R309-525-13(2)(a) Sedimentation Detention Time is to be approved at 45 minutes against 4 hours , R309-525-13(c) Sedimentation Flow
Through Velocity at 1.4 feet per minute against 0.5 feet per minute and R309-525-15(v) Dual Media Rate at 6.9 gpm/sf against 6 gpm/sf regarding the construction of the new City Creek
WTP is on the validation testing completed on the various treatment technologies to ensure treatment goals are met and provide equivalent protection for public health to meet the intent
of the rule as clarified below.
The full scale pilot study took place at City Creek WTP between April 5, 2021 and July 5, 2021. The study tested different treatment processes such as conventional filtration and direct
filtration, and treatment parameters such as filter media type and depth, coagulant type, and filtration rates. The study assessed each process’s ability to meet regulatory requirements
and SLCDPU’s performance goals. The study was strategically performed during the spring snowmelt runoff period because it corresponds to the time when plant flow and raw water turbidity
typically peak.
R309-525-13(2)(a) Sedimentation Detention Time
The plate settler SLR was piloted in 2021. Results from the pilot showed good, settled water performance of <1 NTU with raw water turbidity ≤ 10 NTU and <2 NTU with raw water turbidity

≥10 NTU. Additionally, this same SLR is currently used at the Point of the Mountain WTP and Jordan Valley WTP, both of which have a history of good settled water performance. SLCDPU
determines approval of sedimentation detention time of 45 minutes would meet the intent of the rule.
R309-525-13(c) Sedimentation Flow- Through Velocity
The CCWTP will have a flow through velocity of approximately 1.4 ft/min. The implementation of high-rate sedimentation in the form of inclined plate settler equipment addresses concerns
with this higher flow rate by: [1] providing an enclosed space between any two consecutive plates which minimizes the influence of outside flow conditions and environmental influences
(e.g. wind, debris); [2] establishing uniform flow within the space through the weirs and orifices, which encourage a uniform transfer of settled water into the troughs; [3] establishing
an isolated area above each plate pack in which settled water remains isolated from unsettled water; [4] increasing settling area within a compact volume, which reduces horizontal velocities
within each space to 0.67 ft/min and minimizes settling distance; and [5] continuously removing settled solids from the settling area to minimize potential for resuspension of particulates.
SLCDPU determines approval of flow through velocity of 1.4 ft/min would meet the intent of the rule.
R309-525-15(v) Dual Media Rate
During pilot study conducted in 2021, SLCDPU completed testing two different dual media profiles and filtration rates of 8 gpm/ft2 and 10 gpm/ft2. The piloting showed that one of the
media configurations had good filter performance, filtered water turbidity, and terminal head- loss for filtration rates up to 10 gpm/ft2. This media configuration is specified in the
CCWTP Upgrades BRIC Package project specifications Section 46 61 13 (Filter Media). SLCDPU determines approval of filter rate of at least 6.9 gpm/ft2 would meet the intent of the rule.
SLCPU confirms to maintain all Division required operational monitoring requirements, specifically that the turbidity performance standards for the new City Creek WTP will be less than
0.3 NTU 95% of the time, and shall not exceed 1.0 NTU (per R309-200-5(a)(ii) and R309-530-9) to maintain the facilities 2.5-log credit for Giardia lamblia removal, and 2-log credit for
Cryptosporidium removal for the first stage compliance filter.
On this basis, Temporary Exceptions to R309-525-13(2)(a) Sedimentation Detention Time, R309-525-13(c) Sedimentation Flow Through Velocity and R309-525-15(v) Dual Media Rate are hereby
granted for City Creek Water Treatment upgrade project.
1. This Temporary Exception expires on October 31, 2027.
2.You will be required to re-submit an exception request along with
confirmation that all conditions outlined in this temporary exception have
been fulfilled and obtain an exception renewal prior to October 31, 2027.
a.Exceptions granted by the Division include an expiration date to ensure that the basis and conditions for granting the exception are verified periodically and that the drinking water
quality remains protected. After receiving your request, the Division will determine whether this exception can be re-issued.
b.Failure to request the re-evaluation of this exception and obtain an exception renewal by October 31, 2027, will result in the activation of the deficiency related to not having a
permanent flow measuring device on springs.
3. This Temporary Exception may be rescinded any time if new evidence
indicates that the conditions of this exception are no longer being met or a
public health risk exists due to this exception.
We have completed our review of the plans and specifications; stamped and signed bySteve Benchley, P.E., dated July 23, 2024,and find they basically comply with the applicable portion
of Utah’s Administrative Rules for Public Drinking Water Systems in R309. On this basis, the plans for City Creek WTP (TP003) Facilities Upgrade are hereby approved.
This temporary Direct Filtration will be in operation until full renovation of CCWTP is completed tentatively estimated by February of 2025 after which CCWTP will resume as a conventional
treatment plant like existing one. The monthly WTP monitoring spreadsheet as modified for Direct Filtration must be used by the operator for monthly reporting to the Division until conventional
operations are resumed. At this point, a new reporting template representing the updated CCWTP configuration must be used.
This approval pertains to construction only. An Operating Permit must be obtained from the Director for City Creek WTP (TP003) Facilities Upgrade before putting in service. A checklist
outlining the items required for operating permit issuance is enclosed for your information.Approvals or permits from the local authority or the county may be necessary before beginning
construction of this project. As the project proceeds, notice of any changes in the approved design, as well as any change affecting the quantity or quality of the delivered water, must
be submitted to the Division. We may also conduct interim and final inspections of this project. Please notify us when actual construction begins so that these inspections can be scheduled.
This approval must be renewed if construction has not begun or if substantial equipment has not been ordered within one year of the date of this letter.
If you have any questions regarding this approval, please contact Nagendra Dev, P.E., of this office, at (801) 68-5296, or Michael Newberry, P.E., at [phone].
Sincerely,
Russell Seeley, P.E.
Assistant Director
ND/mrn/mdbEnclosures –Operating Permit Checklistcc:Matthias Neville, Salt Lake County Health Department, [e-mail] Brenchley, Brown & Caldwell, [e-mail]
Adam Jones, Brown & Caldwell, [e-mail]
Nathan Hall, Brown & Caldwell, [e-mail]
Jared Carr, Jacobs Engineering, [e-mail]
Teresa Gray, Salt Lake City Public Utilities, [e-mail]
Michelle Barry, Salt Lake City Public Utilities, [e-mail]
Sarah Page, PhD, Division of Drinking Water, [e-mail]
David Kruse, Division of Drinking Water, [e-mail]
Mark Burger, Division of Drinking Water, [e-mail]
Nagendra Dev, P.E., Division of Drinking Water, [e-mail]
NDev PA Package 3 City Creek 18026 12496
Utah Division of Drinking Water ― Checklist for Issuing Operating PermitsWater System Name: ______________________________System Number: _______________Project Description: _______________________________File
Number: __________________
Items 1 through 11 below must be submitted to the Division and found to be acceptable prior to operating permit issuance (unless a water line project meets the requirements of R309-500-7
and is not required to obtain an Operating Permit).☐1.Certification of Rule Conformance by a professional engineer (P.E.) that all conditions of Plan Approval were accomplished, and
if applicable, changes made during construction were in conformance with rules R309-500 through 550☐2.As-built or record drawings incorporating all changes to approved plans and specifications
(unless no changes were made to the previously approved plans during construction)☐3.Confirmation that as-built or record drawings have been received by the water system☐4.Satisfactory

bacteriological samples as evidence of proper disinfection and flushing in accordance with the appropriate ANSI/AWWA standards:
☐ANSI/AWWA C651-14 AWWA Standard for Disinfecting Water MainsTwo consecutive sample sets at least 16 hours apart, nonpositive (e.g., every 1,200 feet, end-of-line, each branch)☐ANSI/AWWA
C652-11 AWWA Standard for Disinfection of Water-Storage Facilities (e.g., clearwell, storage tank).One or more samples, nonpositive☐ANSI/AWWA C653-13 AWWA Standard for Disinfection of
Water Treatment PlantsTwo consecutive samples per unit (filter), nonpositive, no less than 30 minutes apart☐ANSI/AWWA C654-13 AWWA Standard for Disinfection of WellsTwo consecutive samples,
nonpositive, no less than 30 minutes apart☐5.Water quality data — Work with WQ Specialist to Specify the required finished water and/or raw water data to demonstrate WTP performance
before an OP can be issued, e.g., turbidity data/interval/frequency/sampling location, UVT data/off specs %, chlorine residual.Example:
New source chemistry data on combined raw water (with recycle) and finished water (one sample each)
IFE, CFE and clearwell turbidity (highest reading at 4-hour intervals for a minimum of 7 days)
Minimum chlorine residual, pH and temp, min. volume for detention time calculations (daily for a minimum of 7 days)
UV data: minimum validated dose, UVT% (daily for a minimum of 7 days)
☐6. If applicable, all other documentation that may have been required during the plan review process.☐7. SWTR monthly report with at least 7 days of operational data demonstrating SWT
has been achieved. The WTP does not have to operate at full capacity or continuously (but at least 4 hours per day) for the purpose of this demonstration.☐8. Confirmation of turbidimeter
calibration.☐9. For membrane treatment:a statement of knowledge that the facility startup of Subsection R309-530-8(9) have been completed.normalized operating flux range.normalized operating
flux per membrane unit.maximum operating differential pressure for a membrane unit.membrane unit backwashing frequency.minimum, verified, operation, direct integrity testing resolution.maximum,
verified, operational, direct integrity testing sensitivity.verified, operational, direct integrity control limit.verified, indirect integrity monitoring performance-based upper control
limit.☐10.If applicable, confirmation that the water system owner has received the O&M manual for the new facility.☐11.If applicable, the location data of the new storage tank, treatment
facility, or source