DDW-2024-007555

May 13, 2024
James Papola
Zion Canyon Water System
Zion National Park
State Road 9
Springdale, Utah, 84767
Subject:Operating Permit, Birch-Watercress Treatment Plant (TP001), Lower Grotto Treatment Plant (TP003), Upper Grotto Treatment Plant (TP004), and associated facilities including: Birch
Spring Hydro (HD001), Lower Grotto Pump (PF001), Birch Spring Pump (PF002), and Birch Emergency Pump (PF003); Exception to Rule R309-500-6(2)(e), Utah PE Requirement;
Zion Canyon Water System; System #27051, File #11908
Dear James Papola:This letter provides a summary of the Division of Drinking Water’s decision to issue an Operating Permit for the Birch-Watercress Treatment Plant (TP001), Lower Grotto
Treatment Plant (TP003), and Upper Grotto Treatment Plant (TP004). The letter includes the following sections and addenda:Operating Permit for Birch-Watercress Treatment Plant (TP001),
Lower Grotto Treatment Plant (TP003), and Upper Grotto Treatment Plant (TP004) Surface Water Treatment Plants,Exception to R309-500-6(2)(e) Utah P.E. Requirement,Project Overview (Addendum
1),Compliance Strategy for Achieving Surface Water Treatment Goals (Addendum 2), andSummary of Surface Water Treatment Monitoring and Reporting Regulations (Addendum Operating Permit
for Birch-Watercress Treatment Plant (TP001), Lower Grotto Treatment Plant (TP003), and Upper Grotto Treatment Plant (TP004)Surface Water Treatment Plant
We have received the following information prior to issuing the Operating Permit for Birch-Watercress Treatment Plant (TP001), Lower Grotto Treatment Plant (TP003), and Upper Grotto
Treatment Plant (TP004) Surface Water Treatment Plants:
Certification of Rule Conformance with plan approval conditions by a professional engineer Matthew Hirschbeck, P.E., dated April 27, 2023.
As Built drawings.
Satisfactory bacteriological results as evidence of proper disinfection and flushing.
Evidence of O&M manual delivery.
Water quality data — Seven days of acceptable operational data for the Birch-Watercress Treatment Plant (TP001) was received in April 2024, seven days of acceptable operational data
for the Lower Grotto Treatment Plant (TP003) and the Upper Treatment Plant (TP004) was received in March 2024.
We have determined that all conditions for operating permit issuance have been met. On this basis, an Operating Permit for Birch-Watercress Treatment Plant (TP001), Lower Grotto Treatment
Plant (TP003), and Upper Grotto Treatment Plant (TP004)water treatment plant is hereby issued as constituted by this letter. You may now place these plants in service in your water system.

Please maintain a copy of this letter with your permanent records for future reference. Exception to Rule R309-500-6(2)(e), Utah P.E. Requirement was granted on April 16, 2021Utah code
58-1-307(1)(a) allows an exemption from Utah licensure for employees of federal agencies while engaging in activities as part of their employment, provided they have a valid license
issued by another state recognized by Utah.
An exception to Rule R309-500-6(2)(e), Utah P.E. Requirement was granted as a part of the Conditional Plan Approval issued on April 16, 2021. The Division considers it acceptable that
the Birch-Watercress Treatment Plant (TP001), Lower Grotto Treatment Plant (TP003), and Upper Grotto Treatment Plant (TP004) were designed and stamped by an engineer holding a Colorado
P.E. license. If this Operating Permit changes any of your monitoring requirements, the staff of the Water Quality Monitoring and Standards Section will follow up to provide an updated
monitoring schedule to you. Please contact Mark Berger, Water Quality Monitoring and Standards Manager, at [phone] for assistance regarding the monitoring and reporting requirements
for your water system.
If you have any questions regarding this Operating Permit, please contact Dani Zebelean, P.E., of this office, at [phone], or Michael Newberry, P.E., Permitting and Engineering
Manager, at [phone].
Sincerely,
Russell Seeley, P.E.
Assistant Director
DZ/mrn/mdbEnclosuresAddendum 1. Project OverviewAddendum 2. Compliance Strategy for Achieving Surface Water Treatment GoalsAddendum 3. Summary of Surface Water Treatment Monitoring and
Reporting Regulationscc:Jeremy Roberts, Southwest Utah Health Department, [e-mail] Papola, Zion Canyon Water System, [e-mail] MacKay, Zion Canyon
Water System, [e-mail]
Matthew Hirschbeck, P.E., National Park Service, [e-mail] Wright, P.E., DEQ Southwest District Engineer, [e-mail]
Dani Zebelean, P.E., Division of Drinking Water, [e-mail]
Sitara Federico, Division of Drinking Water, [e-mail]
Luke Treutel, Division of Drinking Water, [e-mail]
David Kruse, Division of Drinking Water, [e-mail]
Sarah Page, Ph.D., Division of Drinking Water, [e-mail]
DZebelean 27051 11908 OP TP001 TP003 TP004ADDENDUM 1Project Overview
Zion Canyon Water System Water System (UTAH#27051)
Birch Creek-Watercress Treatment Plant (TP001)
Lower Grotto Treatment Plant (TP003)
Upper Grotto Treatment Plant (TP004)
Project Summary
The Division of Drinking Water (the Division) received a request for an Operating Permit for the Birch-Watercress Treatment Plant (TP001), Lower Grotto Treatment Plant (TP003), and Upper
Grotto Treatment Plant (TP004) from your consultant, Mathew Hirschbeck, P.E. on April 27, 2023. The final water quality data was received and concurred with on April 10, 2024. The Division
issued Plan Approval for this project on April 16, 2021.
This review also included the review of the following facilities respectively in the Division’s database:
Birch Creek - Watercress Treatment Plant (TP001)
Lower Grotto Treatment Plant (TP003)

Upper Grotto Treatment Plant (TP004)
Birch Spring Hydropneumatic Tank (HD001)
Lower Grotto Pump (PF001)
Birch Spring Pump (PF002)
Birch Emergency Pump (PF003)
Project Background
Zion Canyon Water System serves the Zion National Park and is owned and operated by the National Park Service. Our understanding of the project is that unapproved bag filters were observed
during the Zion Canyon Water System’s 2019 Sanitary Survey. The Division had no record of plan approval or operating permits and issued a deficiency code G001 for operation of unapproved
facilities to the water system. The Division’s compliance actions prompted the National Park’s engineers to complete a formal review of the water system to ensure compliance and protection
of the public’s drinking water.
The National Park’s engineers worked closely with the Division to review the existing drinking water facilities. During this review the National Park’s engineers stated they could not
find sufficient raw source sampling history to support the removal of the unapproved treatment systems. Instead, the National Park’s Engineers completed a review of the entire drinking
water system and proposed the following redesign to provide adequate treatment should any of the source waters in the future ever be classified as groundwater under the direct influence
of surface water (GWUDI). Groundwater classified as GWUDI must meet the surface water treatment rules, which require removal or inactivation, expressed in terms of Log10 credit, of Cryptosporidium,
Giardia lamblia, and viruses through treatment techniques, disinfection, and inactivation.
Inadequate bacteriological data was unavailable at the time of the plan review to determine if disinfection or surface water treatment was required for the Birch Springs (WS001), Watercress
Springs (WS002), Lower Grotto Spring (WS003), or Upper Grotto Spring (WS004). However, the National Park’s engineers requested a plan review of the proposed Birch Watercress Treatment
Plant (TP001), Lower Grotto Treatment Plant (TP003), and Upper Grotto Treatment Plant (TP004). Since the conditional plan review was granted on April 16, 2021, Zion Canyon Water System
has collected sufficient raw water source data for the springs.
Birch Creek - Watercress Treatment Plant (TP001)
The Birch Springs (WS001) and Watercress Spring (WS002) are located near one another and are combined for treatment. Previously, disinfection was the only treatment process for the combined
flows. The project created a new treatment building to house new filters and upgraded disinfection equipment. The new building stores bulk sodium hypochlorite, a pump, and hydropneumatic
tank for the adjacent housing units. The existing electrical equipment was relocated to the new building as well. The new Birch Spring Pump (PF002) is included in the new treatment building
to provide sufficient pressure for the treatment process and fill the Birch Reservoir (ST001). The Birch Reservoir (ST001) is a 1,000,000-gallon welded steel reservoir located about
50 feet south of the new treatment building.
The Birch Creek - Watercress Treatment Plant (TP001) has a plant design capacity of 160 gallons per minute (gpm). This plant has 2train(s) of the following processes, and each train
of 160 gpm.
The treatment plant consists of the following processes in sequence:
Combined flows from the Birch Springs (WS001) and Watercress Spring (WS002).
First-stage pre-filters – Harmsco Municipal-3-3FL-304 housing fitted with three Model HC/170-1 polyester filter cartridges in parallel (1 micron, 30.75-inch long cartridge, 170 square
feet (sq.ft.)); 2 trains; 160 gpm per train.
First-stage compliance filter – Harmsco Municipal-3-3FL-304 housings fitted with three Model HC/170-LT2 pleated microglass filter cartridges in parallel (1 micron, 30.75 inch-long cartridge,
120 sq.ft.); 2 trains; 160 gpm per train.
Post-chlorination – liquid sodium hypochlorite; 6.25% concentration.
Clear Well - 350,000 gallons of the Birch Creek Reservoir (ST001) will be used for the disinfection contact time (CT).
The estimated disinfection CT is 66, which will meet the 0.5-log10Giardia and 4-log10 virus inactivations requirements. The CT calculations are based on the CT from the 350,000 gallon
portion of the Birch Reservoir (ST001). The chlorination CT calculations are determined using a minimum free chlorine residual of 0.3 ppm, a peak flow rate of 160 gpm, at a pH of 8.77,
a temperature of 0.5 degrees Celsius, and a baffling factor of 0.1.
The tank levels must be maintained above 8 feet or greater in order to achieve the disinfection CT requirements.
The point of entry is on the discharge line of the Birch Reservoir (ST001) line located within the treatment building and tees prior to the hydropneumatic tanks.
Monitoring and Reporting locations:
Raw Water Analyzers consist of Hach Brand, Model TU5300sc Turbidimeter with automatic cleaning, Hach Brand, Model pHDsc pH, and Temperature analyzers
After the two trains of Hach Brand, Model HC/170-LT2 (1 micron, 30.75-inch long cartridge there is a Hach Brand, Model TU5300sc Turbidimeter that will be the combined filter effluent
(CFE) compliance location.
Analyzers for finished water (or) Analyzers for the end of the disinfection CT Sequence, Hach Brand Model CLF10sc chlorine residual analyzer, Hach Brand, Model pHDsc pH and Temperature
analyzer.
Lower Grotto Treatment Plant (TP003) and Upper Grotto Treatment Plant (TP004)
The Lower Grotto Spring (WS003) and Upper Grotto Spring (WS004) are located near each other, but are hydraulically separate. The Upper Grotto Spring (WS004) has the higher Hydraulic
Grade Line (HGL) than the Lower Grotto Spring (WS003). Water from both sources is treated in separate filtration trains but combine into the same disinfection CT sequence. Both trains
are housed in the same treatment building. This project created new filtration processes in series with upgraded disinfection equipment. The building also includes the Lower Grotto Pump
(PF001), to act as a pump to allow the Lower Grotto Spring (WS003) treated water to overcome the HGL of the Upper Grotto Spring (WS004). In addition, the Grotto Reservoir (ST002) is
a 300,000-gallon, welded steel tank that is located about 750 feet south of the treatment building.
The Lower Grotto Treatment Plant (TP003) has a plant design capacity of 60 gallons per minute (gpm). This plant has 2train(s) of the following processes, and each train of 60 gpm. The
Upper Grotto Treatment Plant (TP004) is the same as the Lower Grotto Treatment Plant (TP003).
The treatment plants consist of the following processes in sequence:
The Lower Grotto Treatment Plant (TP003) treats the flows from Lower Grotto Spring (WS003). The Upper Grotto Treatment Plant (TP004) treats the flows from the Upper Grotto Spring (WS004).
First-stage pre-filters – Harmsco Municipal-1-2FL-304 housing fitted with one Model HC/170-1 polyester filter cartridges in parallel (1 micron, 30.75-inch long cartridge, 170 sq.ft.);
2 trains; 60 gpm per train.
First-stage compliance filter – Harmsco Municipal-1-2FL-304 housing fitted with one Model HC/170-LT2 pleated microglass filter cartridges in parallel (1 micron, 30.75-inch long cartridge,
120 sq.ft.); 2 trains; 60 gpm.

Post-chlorination – liquid sodium hypochlorite; 1.36% concentration.
Clear Well - a 250,000-gallon portion of the Grotto Reservoir (ST002) is used for the disinfection CT before releasing into the distribution system.
The estimated CT is 66, which will meet the 0.5-log10Giardia and 4-log10 virus inactivation requirement. The CT calculations are based on the CT from the 250,000-gallon portion of the
Grotto Reservoir (ST002) and approximately 901 feet of 4-inch pipeline between the treatment plant building and the Grotto Reservoir (ST002). The chlorination CT calculations are determined
using a minimum free chlorine residual of 0.3 ppm, a peak flow of 120 gpm from both treatment plants, at a pH of 8.77, a temperature of 0.5 degrees Celsius, and a baffling factor of
0.1.T
The tank levels must be maintained above 6 feet or greater in order to achieve disinfection CT requirements.
The point of entry is the lines that tees off the discharge from the Grotto Reservoir (ST002) that tees and comes back to the treatment building.
Monitoring and Reporting locations are mirrored from the Birch Creek - Watercress Treatment Plant (TP001) above.
Each of the filter housings is equipped with differential pressure monitoring to inform filter cleaning and replacement intervals. Filter cartridge run times will be determined by upstream
and downstream differential pressure (pressure loss across the filter). Operators will observe the differential pressure on each visit and remove and wash the pre-filter cartridges when
the pressure loss reaches approximately 8 pounds per square inch (psi) or replace them entirely when the pressure loss reaches approximately 25 psi. The compliance filters can reach
up to a differential pressure of 30 psi before needing replacement. Compliance filter cartridges will be replaced rather than washing and replacing. ADDENDUM 2Compliance Strategy for
Achieving Surface Water Treatment Goals
Zion Canyon Water System Water System (UTAH#27051)
Birch Creek-Watercress Treatment Plant (TP001)
Lower Grotto Treatment Plant (TP003)
Upper Grotto Treatment Plant (TP004)Treatment Goals per Surface Water Treatment Rules
The Birch Creek - Watercress Treatment Plant (TP001), Lower Grotto Treatment Plant (TP003), and Upper Groot Treatment Plant (TP004) treatment plant consist of pre-filtration, filtration,
and chlorination processes. These plants are designed to meet the requirements of the surface water treatment rules, as incorporated into Utah’s Rules in R309. These surface water treatment
rules require removal and/or inactivation, expressed in terms of log10 credit, of Cryptosporidium, Giardia lamblia, and viruses through treatment techniques.
The Surface Water Treatment Rule (SWTR) requires:
3-log10 removal/inactivation for Giardia lamblia, and
4-log10 removal/inactivation for virus.
The Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR) established four bin classifications for Cryptosporidium based on concentration in the source water. If a water system
has source water classified in Bin 1, LT2ESWTR requires 2-log10 removal forCryptosporidium. If a water system has source water in Bin 2, Bin 3, or Bin 4, LT2ESWTR requires additional
treatment, disinfection or inactivation for Cryptosporidium, as outlined in EPA’s “Long Term 2 Enhanced Surface Water Treatment Rule Toolbox Guidance Manual.”
Since all water sources being treated at TP001, TP003, and TP004 are currently designated as groundwater sources, the monitoring requirements of the LT2ESWTR do not apply. If in the
future any water source being treated at TP001, TP003, or TP004 is designated as being groundwater under direct influence of surface water (GUDI), the monitoring required in the LT2ESWTR
must be completed.
In the event additional log removal credit is needed for a higher Bin classification, additional treatment will need to be installed. New Plan Approval would be required for any additional
treatment.Compliance StrategyPrimary FiltrationThe compliance filtration process for each treatment plant is a Harmsco Model HC/170-LT2 compliance filtration process is granted for the
following treatment credits (3 cartridges per unit for TP001, and a single cartridge per unit for TP003 and TP004).Operated as direct filtration and meeting a turbidity performance standard
of 0.3 NTU 95% of the time or less (not to exceed 1.0 NTU)2.5 log removal for Giardia lamblia3.0 log removal for Cryptosporidium
According to the Colorado Department of Public Health and Environment letter dated December 2015, the cartridge filtration process using the Harmsco Model HC/170-LT2 filtersis credited
for providing 2.5-log10 removal for Giardia lamblia and 3.0-log10 removal for Cryptosporidiumprovided the following requirements are met:
Birch Creek-Watercress Treatment Plant (TP001) - Using the Harmsco Municipal 3-3-FL-304 housing with the Harmsco HC/170-LT2 Filters can operate within the maximum flow of 300 gallons
per minute (gpm) and 30 pounds per square inch (psi) of differential pressure.
Lower Grotto Treatment Plant (TP003) and Upper Grotto Treatment Plant (TO004) - Using the Harmsco Municipal 1-2FL-304 housing with the Harmsco HC/170-LT2 filter can operate within the
maximum flow of 100 gpm and the maximum 30 psi of differential pressure.
The Division concurs with granting the same treatment credits for the Harmsco HC/170-LT2 filters.The Division approvesthe cartridge filtration process using Harmsco HC/170-LT2 filters
as an alternative filtration technology for primary filtration under the surface water treatment rules. The Division grants 3.0-log10 credit for Giardia lamblia removal, and 2.5-log10
credit for Cryptosporidium removal for the first stage compliance filter.
Per R309-200-5(5)(a)(ii), the turbidity performance standard for this treatment plant is thatthe turbidity shall be less than 0.3 NTU 95% of the time, and shall not exceed 1.0 NTU.
Disinfection
Disinfection processes installed after the Harmsco Model HC/170-LT2 filters in each of the treatment plants provide additional treatment for meeting the Bin 1surface water treatment
goals:
Post chlorination at target residual of 0.3 ppm is provided for additional disinfection following the Harmsco Filters. The treatment plants provide disinfection through adding liquid
sodium hypochlorite. This process provides additional primary disinfection treatment to meet the additional 0.5-log10 inactivation of Giardia lamblia and 4-log10 virus inactivation requirement
for compliance with the Bin 1 surface water treatment rules.
Birch Creek - Watercress Treatment Plant (TP001)
The estimated disinfection CT is 66, which will meet the 0.5-log10 Giardia and 4-log10 virus inactivation requirement. The CT calculations are based on the CT from a 350,000-gallon portion
of the Birch Reservoir (ST001). The chlorination CT calculations are determined using a minimum free chlorine residual of 0.3 ppm, a peak flow of 160 gpm, at a pH of 8.77, a temperature
of 0.5 degrees Celsius (C), and a tank baffling factor of 0.1. The level in the Birch Reservoir (ST001) must be maintained at greater than 8 feet to achieve CT requirements.
The point of entry is on the discharge line of the Birch Reservoir (ST001) line located within the treatment building and tees prior to the hydropneumatic tanks
Lower Grotto Treatment Plant (TP003) and Upper Grotto Treatment Plant (TP004)
The estimated disinfection CT is 66, which will meet the 0.5-log Giardia and 4-log virus inactivation requirement. The CT calculations are based on the CT from the 250,000 gallon portion
of the Grotto Reservoir (ST002) and approximately 901 feet of 4-inch diameter pipeline between the grotto treatment building and the Grotto Reservoir (ST002). The chlorination CT calculations
are determined using a minimum free chlorine residual of 0.3 ppm, a peak flow of 120 gpm (flows from both TP003 and TP004), at a pH of 8.77,a temperature of 0.5 degrees C, and a tank
baffling factor of 0.1. The level in ST002 must be maintained at 6 feet or greater to achieve CT requirements.

The point of entry is the lines that tees off the discharge from the Grotto Reservoir (ST002) that tees and comes back to the treatment building.
In the event additional log removal credit is needed for a higher Bin classification per LT2ESWTR requirements, additional treatment will need to be installed. New Plan Approval would
be required for any additional treatment.
Overall, the Birch Creek-Watercress Treatment Plant (TP001), Lower Grotto Treatment Plant (TP003), and the Upper Grotto Treatment Plant (TP004) design meets the required treatment for
Cryptosporidium for surface water classified as in Bin 1 under R309-215-15 of Utah’s Rules. The processes of pre-filtration, cartridge filtration process, and the post-chlorination together
will achieve the treatment goals of:
3.0-log10 removal and inactivation required for Giardia lamblia,
2.0-log10 removal required for Cryptosporidium (Bin 1 requirement), and,
4.0-log10 inactivation for virus.
ADDENDUM 3
Summary of Surface Water Treatment Monitoring and Reporting Regulations
Zion Canyon Water System Water System (UTAH#27051)
Birch Creek-Watercress Treatment Plant (TP001)
Lower Grotto Treatment Plant (TP003)
Upper Grotto Treatment Plant (TP004)
This Addendum summarizes the monitoring and reporting regulations related to the Birch Creek-Watercress Treatment Plant (TP001), Lower Grotto Treatment Plant (TP003), and the Upper Grotto
Treatment Plant (TP004). Birch Creek-Watercress Treatment Plant (TP001), Lower Grotto Treatment Plant (TP003), and Upper Grotto Treatment Plant (TP004) are currently treating groundwater
sources and thus are not required to meet surface water treatment requirements. Zion Canyon Water System has agreed to comply with the monitoring and reporting requirements of the surface
water treatment matching the treatment installed. Monitoring and reporting violations may be issued if these requirements are not met. However, treatment technique violations will not
be issued unless any groundwater standard or secondary disinfections treatment requirement is violated. In the future if any source feeding Birch Creek-Watercress Treatment Plant (TP001),
Lower Grotto Treatment Plant (TP003), and Upper Grotto Treatment Plant (TP004) is required to treat to surface water standards (ie is designated as groundwater under the direct influence
of surface water), all monitoring and reporting requirements, as well as treatment techniques requirements, must be met for surface water treatment.
Monthly Report — General
The Zion Canyon Water Systemwater system (the System) is required to complete a monthly report for Birch Creek-Watercress Treatment Plant (TP001), Lower Grotto Treatment Plant (TP003),
and the Upper Grotto Treatment Plant (TP004)using a template approved by the Division of Drinking Water (the Division). As a minimum, the monthly surface water treatment plant report
must include the following data and other applicable information.
Rawwater pH, Temperature, turbidity, and flow rate. [R309-530-8(8)(p) and (q)].
Combined filter effluent (CFE) turbidity [R309-215-9(1)(a)]
Minimum chlorine residual of the treated water at the point of entry (POE).
Verification and calibration dates of turbidimeter(s)
Sufficient residual concentration, volume, flow, tank level, pH, and temperature readings in order to prove disinfection CT and/or Inactivation ratio demonstrating whether the log removal/inactivation
requirements are met R309-200-5(7), R309-215-15(19);
Submit the surface water treatment plant report for the entire month to the Division by the 10th of the following month. This report must be submitted by e-mail as an Excel file at [e-mail].
Please contact Sarah Page at [phone] or [e-mail] to schedule training regarding proper reporting.
All operational records pertaining to the monthly surface water treatment plant reports shall be maintained for a minimum of 5 years. [R309-105-17]
Treatment Adequacy [R309-200-5(7), R309-215-15(19) and (20)]
Water systems using surface water or groundwater under the direct influence of surface water must provide treatment consisting of both disinfection and filtration. [R309-200-5(5)(a)]..
The surface water treatment plant monthly report must include both disinfectionand filtration processes. The monthly report shall contain sufficient information to indicate whether the
minimum surface water treatment requirements (i.e., log removal/inactivation of Giardia, virus, and Cryptosporidium) are met
Required Treatments Credit — Birch Creek-Watercress Treatment Plant (TP001), Lower Grotto Treatment Plant (TP003), and Upper Grotto Treatment Plant (TP004) are currently treating groundwater
sources and thus are not required to meet surface water treatment requirements. The treatment credits grantedfor the processes in Birch Creek-Watercress Treatment Plant (TP001), Lower
Grotto Treatment Plant (TP003), and Upper Grotto Treatment Plant (TP004)are summarized below.
Zion Canyon Water System (UTAH#27051)
Birch Creek-Watercress Treatment Plant (TP001),
Lower Grotto Treatment Plant (TP003), and
Upper Grotto Treatment Plant (TP004)
Primary Treatment Technique: Alternative Filtration with Cartridge Filters
Treatment Goals
(Minimum Treatment Requirements)
Giardia
Virus
Cryptosporidium
3-log removal / inactivation
4-log removal / inactivation
2-log removal
(Bin 1 source water)
Processes
Credit Granted
Alternative Filtration1 (Harmsco Model HC/170-LT2)
2.5 - log removal

N/A
2.0-log removal
Chlorine2
0.5-log inactivation
4.0-log inactivation
N/A
Total Treatment Credit
3.0-log removal / inactivation
4.0-log inactivation
2.0-log removal
Granted based on the Colorado Department of Public Health and Environment grants the Harmsco Model HC/170-LT2 filter with 2.5-Log10 removal credit for Giardia lamblia and 2.0-Log10 removal
credit for Cryptosporidium in its Summary of Accepted Bag and Cartridge Alternative Filtration Technologies listing dated January 2021. The Division concurs with granting the same treatment
credits for the proposed filter.
Based on the CT calculation by Anthoney Beeson, P.E. of the National Park Service during the plan review process and approved with the plan approval dated April 16, 2021.
Disinfection
The System is required to continuously disinfect the treated water from this WTP.
The disinfection treatment shall be sufficient to ensure the total treatment processes of this WTP achieve at least 3-log inactivation/removal of Giardia lamblia, 4-log inactivation/removal
virus, and a minimum of 2.0-log Cryptosporidium removal (for treating Bin 1 source water). [R309-200-5(7)(a)(i); R309-215-15(12)].
The calculated disinfection CT for all processes shall be reported monthly to indicate the level of disinfection effectiveness. [R309-215-15(19)]
Disinfection at Point of Entry (POE)[R309-200-5(7), R309-215-15(19)]
The System is required to continuously disinfect the treated water from this WTP. [R309-200-5(7)]
The chlorine residual must not be below 0.2 milligram per liter (mg/L) free chlorine residual at the point of entry (POE), where the treated water enters the distribution system, for
more than four hours. [R309-200-5(7)(a)(ii)]
The chlorine residual must not exceed the maximum residual disinfectant level (MRDL) of 4.0 mg/L free chlorine residual. [R309-200-5(3)(c)(iv) Table 200-5]
Lowest Daily POE chlorine residual readings shall be collected and recorded on the monthly report.
Systems serving a population greater than 3,300 shall continuously monitor chlorine residuals at the POE
The chlorine analyzer should be verified for accuracy or calibratedat least quarterlyper Standard Method 334.0 Determination of Residual Chlorine in Drinking Water Using an Online Chlorine
Analyzer. [EPA 815-B-09-013 September 2009 11.1.1.2 Page 13]
A Hach Pocket Colorimeter DPD colorimetric method (e.g. Method 8021) is an acceptable method for verifying on-line chlorine residual analyzers (e.g. for Hach Cl17 online analyzer). If
the verification fails, online analyzer adjustments will be made until the accuracy is achieved. A calibration will be conducted if verification testing cannot be accomplished successfully.
Turbidity Limit Issues
Filtration Technologies Other Than Conventional Filtration, Direct Filtration, Slow Sand Filtration, or Diatomaceous Earth Filtration [R309-200-5(5)(a)(ii); R309-215-9(1)]
The turbidity of the treated water or the combined filter effluent (CFE) shall be less than or equal to 0.3NTU in at least 95% of the measurements taken each month. The treated water
or CFE turbidity shall at no time exceed 1.0NTU.
The turbidity level of the treated water or the combined filter effluent (CFE) shall not exceed 5.0 NTU for any treatment technique.
Turbidity Monitoring and Reporting — General
The turbidity readings during the operation and maintenance procedures, such as plant start-up, clean-in-place, enhanced flux maintenance, air scrub, integrity tests, etc., can be excluded
from the report. Operational logs and/or SCADA shall reflect the conditions causing false turbidity readings.
If a data recording delay is programmed into SCADA after plant start-up, the delay shall not exceed 15 minutes and the System shall inform the Division of the programming details
Signal averaging is not allowed.
The turbidity of the combined filter effluent (CFE) and each individual filter effluent (IFE) shall be continuously monitored. [See R309-215-9(1)(a) for CFE monitoring, and R309-525-15(4)(b)(vi)
and (4)(c)(vii) for IFE monitoring.]
The turbidity of the combined filter effluent (CFE) and each individual filter effluent (IFE) shall be continuously recorded. [R309-215-9(1)(b)]
The System shall monitor the turbidity results of each IFE at a frequency of no greater than every 15 minutes. [R309-215-9(1)(b)]
The highest CFE turbidity reading at the end of eachfour-hour (or shorter) interval of operation must be included in the monthly surface water treatment plant report submitted to the
Division, excluding data described in #5a. [R309-215-9(1)(b)] Data must be sufficient to determine the information outlined below. [R309-215-9(1)(b); R309-215-9(1)(c), R309-215-9(4)(a)
and R309-215-9(5)(a)]
Total number of the 4-hour combined filter effluent (CFE) turbidity measurements reported during the month (see #5e)
The number and percentage of 4-hour combined filter effluent (CFE) turbidity measurements reported during the month, which are less than or equal to 0.3 NTU, excluding data described
in #5a.
If there is a failure in continuous monitoring equipment, the water system shall conduct grab sampling for turbidity every four hours. [R309-215-9(1)(b)]
The grab sampling, in lieu of continuous monitoring, cannot be more than five working days for water systems serving a population of 10,000 or more, following the failure of equipment.
The grab sampling, in lieu of continuous monitoring, cannot be more than fourteen days for water systems serving a population less than 10,000, following the failure of equipment.
If the set turbidity limit for the approved treatment technology is exceeded, the System must comply with the re-sampling and notification requirements. [R309-215-9(2)]
Re-sample as soon as practicable and preferably within one hour.
If re-sampling confirms the exceedance of the turbidity limit —
The System shall collect at least one bacteriological sample near the first service connection from the source within 24 hours of the turbidity exceedance. This sample result shall be
included in determining bacteriological compliance for that month.
The System shall report this turbidity re-sampling exceedance to the Director as soon as practical, but no later than 24 hours after the turbidity exceedance is known. This reporting
is in addition to reporting the incident on any monthly WTP reports.

The System using a filtration technology other than conventional filtration, direct filtration, slow sand filtration, or diatomaceous earth filtration shall inform the Division as soon
as possible, but no later than the end of the next business day if any time the combined filter effluent (CFE) turbidity in representative samples of filtered water exceeds the maximum
level set by the Director, i.e1.0 NTU for Birch Creek-Watercress Treatment Plant (TP001), Lower Grotto Treatment Plant (TP003), and the Upper Grotto Treatment Plant (TP004). [R309-215-9(6)(b)]
Turbidity Equipment Verification and Calibration
Continuous turbidity monitoring equipment for the combined filter effluent (CFE) and each individual filter effluent (IFE) shall be checked for accuracy and/or re-calibrated at a minimum
frequency ofmonthly. [R309-215-9(1)(d)]
The turbidimeter shall be calibrated andthe accuracy verified at least once per month.
The turbidimeters should be thoroughly cleaned and calibrated with primary standardsat least quarterly.
It is not allowed to calibrate on-line instruments by comparison with a bench-top turbidimeter.
The most recent verification/calibration date for the CFE turbidimeter and each IFE turbidimeter shall be reported on the monthly report.
Source Water Bin Classification
The Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR) established four bin classifications for Cryptosporidium based on concentration in the source water. If a water system
has source water classified in Bin 1, LT2ESWTR requires 2-log10 removal forCryptosporidium. If a water system has source water in Bin 2, Bin 3, or Bin 4, LT2ESWTR requires additional
treatment, disinfection or inactivation for Cryptosporidium, as outlined in EPA’s “Long Term 2 Enhanced Surface Water Treatment Rule Toolbox Guidance Manual.”
All water sources being treated at TP001, TP003, and TP004 are currently designated as groundwater sources, thus the monitoring requirements of the LT2ESWTR do not apply. If in the future
any water source being treated at TP001, TP003, or TP004 is designated as being GUDI, the monitoring required in the LT2ESWTR must be completed.
In the event additional log removal credit is needed for a higher Bin classification, additional treatment will need to be installed. New Plan Approval would be required for any additional
treatment.